WorldWideScience

Sample records for cathodoluminescence

  1. Cathodoluminescence of uranium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Winer, K.; Colmenares, C.; Wooten, F.

    1984-08-09

    The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

  2. Depth-Resolved Cathodoluminescence of Thorium Dioxide

    Science.gov (United States)

    2013-03-01

    DEPTH-RESOLVED CATHODOLUMINESCENCE OF THORIUM DIOXIDE THESIS Michael G. Lee, Major, USA AFIT...RESOLVED CATHODOLUMINESCENCE OF THORIUM DIOXIDE THESIS Presented to the Faculty Department of Engineering Physics Graduate School of Engineering...PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT-ENP-13-M-21 DEPTH-RESOLVED CATHODOLUMINESCENCE OF THORIUM DIOXIDE Michael G. Lee, BS Major, USA Approved

  3. Cathodoluminescence Microscopy of Nanostructures on Transparent Substrates

    NARCIS (Netherlands)

    Narváez, A.C.

    2014-01-01

    Cathodoluminescence (CL), the excitation of light by an electron beam, has gained attention as an analysis tool for investigating the optical response of a structure, at a resolution that approaches that in electron microscopy, in the nanometer range. However, the application possibilities are limit

  4. Cathodoluminescence Microscopy of nanostructures on glass substrates

    NARCIS (Netherlands)

    Narvaez, A.C.; Weppelman, I.G.C.; Moerland, R.J.; Liv, N.; Zonnevylle, A.C.; Kruit, P.; Hoogenboom, J.P.

    2013-01-01

    Cathodoluminescence (CL) microscopy is an emerging analysis technique in the fields of biology and photonics, where it is used for the characterization of nanometer sized structures. For these applications, the use of transparent substrates might be highly preferred, but the detection of CL from nan

  5. Angle-resolved cathodoluminescence imaging polarimetry

    CERN Document Server

    Osorio, Clara I; Brenny, Benjamin; Polman, Albert; Koenderink, A Femius

    2015-01-01

    Cathodoluminescence spectroscopy (CL) allows characterizing light emission in bulk and nanostructured materials and is a key tool in fields ranging from materials science to nanophotonics. Previously, CL measurements focused on the spectral content and angular distribution of emission, while the polarization was not fully determined. Here we demonstrate a technique to access the full polarization state of the cathodoluminescence emission, that is the Stokes parameters as a function of the emission angle. Using this technique, we measure the emission of metallic bullseye nanostructures and show that the handedness of the structure as well as nanoscale changes in excitation position induce large changes in polarization ellipticity and helicity. Furthermore, by exploiting the ability of polarimetry to distinguish polarized from unpolarized light, we quantify the contributions of different types of coherent and incoherent radiation to the emission of a gold surface, silicon and gallium arsenide bulk semiconductor...

  6. Cathodoluminescence spectra of gallium nitride nanorods.

    Science.gov (United States)

    Tsai, Chia-Chang; Li, Guan-Hua; Lin, Yuan-Ting; Chang, Ching-Wen; Wadekar, Paritosh; Chen, Quark Yung-Sung; Rigutti, Lorenzo; Tchernycheva, Maria; Julien, François Henri; Tu, Li-Wei

    2011-12-14

    Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio.

  7. Cathodoluminescence Imaging Using Nanodiamond Color Centers

    Science.gov (United States)

    Glenn, David; Zhang, Huiliang; Kasthuri, Narayanan; Trifonov, Alexei; Schalek, Richard; Lichtman, Jeff; Walsworth, Ronald

    2011-05-01

    We demonstrate a nanoscale imaging technique based on cathodoluminescence (CL) emitted by color centers in nanodiamonds (NDs) under excitation by an electron beam in a scanning electron microscope (SEM). We have identified several classes of color centers that are spectrally distinct at room temperature and can be obtained with high reliability in NDs with diameters on the order of 50 nm or smaller. Compared to standard CL markers, ND color centers are bright and highly stable under SEM excitation. In conjunction with appropriate functionalization of the ND surfaces, ND-CL will provide nanoscale information about molecular function to augment the structural information obtained with standard SEM techniques. We discuss an exciting application of this approach to neuroscience, specifically in the generation of high-resolution maps of the connections between neurons (``Connectomics'').

  8. Thermo- and cathodoluminescence properties of Sepiolite

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez L, Y. [Universidad Autonoma de Nayarit, Ciudad de la cultura Amado Nervo s/n, 63155 Tepic, Nayarit (Mexico); Correcher, V. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Garcia G, J., E-mail: yamilet.lazcano@uan.edu.mx [Consejo Superior de Investigaciones Cientificas, Museo Nacional de Ciencias Naturales, Jose Gutierrez Abascal 2, 28006 Madrid (Spain)

    2015-10-15

    Full text: Sepiolite, Si{sub 12}Mg{sub 8}O{sub 30}(OH){sub 4}(OH{sub 2}){sub 4}·8H{sub 2}O, has been well studied from the chemical and structural point of view; however, studies on their luminescence properties have been scarcely reported. This work focuses on the thermoluminescence (Tl) and cathodoluminescence (Cl) response of a natural sepiolite from Madrid, Spain previously characterized by means of environmental scanning electron microscope, X-ray fluorescence (X RF) and X-ray diffraction (XRD) techniques. The complexity of the thermoluminescence glow curves of non-irradiated and irradiated samples suggests a structure of a continuous trap distribution involving multi-order kinetics. UV-IR Cl spectral emission shows five peaks centered at 330, 400, 440, 520 and 770 nm. Such emission bands could be due to (i) structural defects, [AlO{sub 4}] or non bridging oxygen hole centers, and (II) the presence of point defects associated with Mn{sup 2+} and Fe{sup 3+}. Sepiolite, which has different household applications such as: moisture control, containment of accidental liquid spillages, in ashtrays to avoid smoke odor, control of liquid leakages, and odours in dustbins and cat litters; is a good candidate for personal dosimetry in the case of radiation accident or radiological terrorism. in situations where knowledge of doses to individuals is required, but monitoring was not planned. (Author)

  9. Cathodoluminescence of natural, plastically deformed pink diamonds.

    Science.gov (United States)

    Gaillou, E; Post, J E; Rose, T; Butler, J E

    2012-12-01

    The 49 type I natural pink diamonds examined exhibit color restricted to lamellae or bands oriented along {111} that are created by plastic deformation. Pink diamonds fall into two groups: (1) diamonds from Argyle in Australia and Santa Elena in Venezuela are heavily strained throughout and exhibit pink bands alternating with colorless areas, and (2) diamonds from other localities have strain localized near the discrete pink lamellae. Growth zones are highlighted by a blue cathodoluminescence (CL) and crosscut by the pink lamellae that emit yellowish-green CL that originates from the H3 center. This center probably forms by the recombination of nitrogen-related centers (A-aggregates) and vacancies mobilized by natural annealing in the Earth's mantle. Twinning is the most likely mechanism through which plastic deformation is accommodated for the two groups of diamonds. The plastic deformation creates new centers visible through spectroscopic methods, including the one responsible for the pink color, which remains unidentified. The differences in the plastic deformation features, and resulting CL properties, for the two groups might correlate to the particular geologic conditions under which the diamonds formed; those from Argyle and Santa Elena are deposits located within Proterozoic cratons, whereas most diamonds originate from Archean cratons.

  10. Cathodoluminescence degradation of PLD thin films

    Science.gov (United States)

    Swart, H. C.; Coetsee, E.; Terblans, J. J.; Ntwaeaborwa, O. M.; Nsimama, P. D.; Dejene, F. B.; Dolo, J. J.

    2010-12-01

    The cathodoluminescence (CL) intensities of Y2SiO5:Ce3+, Gd2O2S:Tb3+ and SrAl2O4:Eu2+,Dy3+ phosphor thin films that were grown by pulsed laser deposition (PLD) were investigated for possible application in low voltage field emission displays (FEDs) and other infrastructure applications. Several process parameters (background gas, laser fluence, base pressure, substrate temperature, etc.) were changed during the deposition of the thin films. Atomic force microscopy (AFM) was used to determine the surface roughness and particle size of the different films. The layers consist of agglomerated nanoparticle structures. Samples with good light emission were selected for the electron degradation studies. Auger electron spectroscopy (AES) and CL spectroscopy were used to monitor changes in the surface chemical composition and luminous efficiency of the thin films. AES and CL spectroscopy were done with 2 keV energy electrons. Measurements were done at 1×10-6 Torr oxygen pressure. The formation of different oxide layers during electron bombardment was confirmed with X-ray photoelectron spectroscopy (XPS). New non-luminescent layers that formed during electron bombardment were responsible for the degradation in light intensity. The adventitious C was removed from the surface in all three cases as volatile gas species, which is consistent with the electron stimulated surface chemical reaction (ESSCR) model. For Y2SiO5:Ce3+ a luminescent SiO2 layer formed during the electron bombardment. Gd2O3 and SrO thin films formed on the surfaces of Gd2O2S:Tb3+ and SrAl2O4:Eu2+,Dy3+, respectively, due to ESSCRs.

  11. Fabrication and Cathodoluminescence Spectroscopy of Optical Nanostructures

    Science.gov (United States)

    Redinbo, Gregory Finley

    1995-01-01

    This thesis presents the fabrication of buried optical nanostructures in III-V materials by modifying semiconductor quantum wells using an implantation enhanced interdiffusion (IEI) technique. An investigation of the effect of fabrication parameters on the resulting nanostructures is carried out, and the characteristics of the fabricated structures are measured using room temperature and low temperature cathodoluminescence (CL). IEI using protons is reported for the first time in this work and is found to increase the diffusion length of Al in GaAs/AlGaAs single quantum wells. The enhanced diffusion lengths compare favorably to Ga^ {+} IEI studies and the enhanced interdiffusion mechanism is determined to be due to implantation generated point defects. The use of H^{+} IEI for laterally patterning 100-nm optical nanostructures is demonstrated and is found to be limited by the lateral straggle of the light ions during implantation. Optical quantum wires with widths down to 40 nm are fabricated using low energy Ga^{+ } and electron beam lithography generated metal masks on GaAs/AlGaAs quantum wells. Single nanostructures are measured with low temperature CL, and an increasing blue shift of wire emission with decreasing mask size is measured. The lateral extent of intermixing is found to be 30 nm, independent of Ga^{+} implantation energy. Based on a model of emission energy shift, a lateral quantization energy of ~3 meV for carriers is achieved in these structures. Optical nanostructures are also fabricated with direct write IEI using a Ga^{+ } focused ion beam (FIB) and are compared to the quantum wires. A larger effective lateral extent of intermixing of 200 nm is found with the FIB. IEI patterning of strained InGaAs/GaAs quantum wells is demonstrated and a model of the resulting lateral bandgap profile leads to a lateral defect diffusion length of ~1 mum. Strain enhanced lateral diffusion of defects during IEI cause this length to be substantially larger than that

  12. Correction: β-Sialon nanowires, nanobelts and hierarchical nanostructures: morphology control, growth mechanism and cathodoluminescence properties

    Science.gov (United States)

    Huang, Juntong; Huang, Zhaohui; Liu, Yangai; Fang, Minghao; Chen, Kai; Huang, Yaoting; Huang, Saifang; Ji, Haipeng; Yang, Jingzhou; Wu, Xiaowen; Zhang, Shaowei

    2016-07-01

    Correction for `β-Sialon nanowires, nanobelts and hierarchical nanostructures: morphology control, growth mechanism and cathodoluminescence properties' by Juntong Huang, et al., Nanoscale, 2014, 6, 424-432.

  13. Cathodoluminescence study of thin films of high Tc superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Barkay, Z.; Azoulay, J.; Lereah, Y.; Dai, U.; Hess, N.; Racah, D.; Gruenbaum, E.; Deutscher, G. (School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978 Ramat Aviv (Israel))

    1990-10-22

    Cathodoluminescence (CL) of thin films of high {ital T}{sub {ital c}} superconductors was studied in the scanning electron microscope. The depth and the lateral locations of the different phases can be revealed. In thin films, unlike the bulk superconductors, the CL information can be obtained either from the film itself or the substrate by varying the primary beam energy. At high beam energy, substrate defects and slight thickness variations of a single high {ital T}{sub {ital c}} phase are observed. The resolution of the CL measurements improves at low temperatures.

  14. Cathodoluminescence and Magnetic Properties of Mn+ Implanted AIN

    Institute of Scientific and Technical Information of China (English)

    LI Ming-Kai; LI Cheng-Bin; LIU Chuan-Sheng; FAN Xiang-Jun; FU De-Jun; SHON Yun; KANG Tae-Won

    2004-01-01

    @@ The Ⅲ-Ⅴ wide band gap semiconductors show the potential in applications for dilute magnetic semiconductors.AlN films are implanted with 20-keV Mn+ ions with a dose of 5 × 1016cm-2. The cross section of as-implanted AlN are investigated by field-emission scanning electron microscopy and the energy dispersive spectra. The result confirms that the implantation depth is about 100nm. Cathodoluminescence measurements show the main peak at 2.6eV attributed to a donor-to-Mn2+ transition. It is argued that the Mn element in AlN can act as a p-type dopant peak at 2.07eV. The magnetic measurement shows a transition temperature of 100K in the implanted AlN annealed at 500℃ for 30min. Clear ferromagnetic hysteresis was observed at 77K, with a coercive field of 212.7Oe.

  15. Azimuthally polarized cathodoluminescence from InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Brenny, B. J. M.; Osorio, C. I.; Polman, A., E-mail: polman@amolf.nl [Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands); Dam, D. van [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Gómez Rivas, J. [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); FOM Institute DIFFER, P.O. Box 6336, 5600 HH Eindhoven (Netherlands)

    2015-11-16

    We determine the angle and polarization dependent emission from 1.75 µm and 2.50 µm long InP nanowires by using cathodoluminescence polarimetry. We excite the vertical wires using a 5 keV electron beam, and find that the 880 nm bandgap emission shows azimuthally polarized rings, with the number of rings depending on the wire height. The data agree well with a model in which spontaneous emission from the wire emitted into the far field interferes with emission reflected off the substrate. From the model, the depth range from which the emission is generated is found to be up to 400 nm below the top surface of the wires, well beyond the extent of the primary electron cloud. This enables a probe of the carrier diffusion length in the InP nanowires.

  16. Cathodoluminescent properties of Tb3+-doped yttria nanocrystallites

    Institute of Scientific and Technical Information of China (English)

    P.Psuja; D.Hreniak; W.Str(e)k

    2009-01-01

    The Tb3+-doped Y2O3 nanopowders were synthesized using the modified Pechini method.The average size of nanocrystallites was controlled by different sintering temperatures.The structure and morphology of obtained nanopowders were examined using the XRD and SEM analyses.The Cr:Al2O3 was mixed with Tb3+:Y2O3 powders and its normalized emission was used.to measure a relative intensity of Tb3+:Y2O3.The mixtures were electrophorefically deposited on ITO-glass slides.The cathodoluminescence spectra of obtained layers were recorded and analysed.The discussion over an influence of average grains size on phosphor efficiency was presented.

  17. Cathodoluminescence : an imaging technique for the search of extraterrestrial life

    Science.gov (United States)

    Ramboz, C.; Rubert, Y.; Bost, N.; Westall, F.; Lerouge, C.

    2012-04-01

    Solids irradiated by a 10-20 keV electron beam emit ligth in the UV-visible range, which is called cathodoluminescence (CL). CL imagery is a powerful tool for visualizing minerals and their internal structures (lattice defects, zoning). For example, terrestrial calcite, either of sedimentary or biogenic origin, often display a bright orange CL, as a result of the incorporation of trace Mn2+ in its lattice. Aragonite can also be discriminated from calcite by its green CL. Carbonates are a major target for the search of life on Mars, and CL imagery could contribute to reveal carbonates in situ. Thomas et al. [1] have validated the concept of an electron lamp to make CL imagery of a rock surface placed in a martian CO2 atmosphere. We present 2 examples of terrestrial bacterial microstructures that are revealed by CL. (1) In Sinemurian sediments from the Montmiral borehole (Valence Basin, France), banded wavy calcite in contact with pyrite represents fossilized biofilms of sulfato-reducing bacteria, as confirmed by the sulfur isotopic composition of pyrite ~+36 %0 PDB. (2) At l'Ile Crémieux, north of the Valence basin, a dense filamentous microbial/fungal community with a bright orange CL signature is embedded in vuggy calcite from a tectonic vein. The mat is anchored 1-2 mm deep in the oolitic veinwall and emerges at right angle in the 'open' fracture space. Finally, carbonate vesicles and exhalite crusts from the Svalbard basalt in Groendland, with orange CL, are shown as analogues to carbonates from the martian ALH84001 igneous meteorite. [1]Thomas et al. (2009) in A. Gucsik (Ed.) "Cathodoluminescence and Its Application in the Planetary Sciences"

  18. Cathodoluminescence investigations on quartz cement in sandstones of Khabour Formation from Iraqi Kurdistan region, northern Iraq

    DEFF Research Database (Denmark)

    Omer, Muhamed Fakhri; Friis, Henrik

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic stud...

  19. Cathodoluminescence Emission Studies for Selected Phosphor-Based Sensor Materials

    Energy Technology Data Exchange (ETDEWEB)

    Goedeke, Shawn [ORNL; Hollerman, William Andrew [ORNL; Allison, Stephen W [ORNL; Gray, P A [Integrated Concepts and Research Corporation - Huntsville, AL; Lewis, Linda A [ORNL; Smithwick III, Robert W [ORNL; Boatner, Lynn A [ORNL; Glasgow, David C [ORNL; Ivanov, Ilia N [ORNL; Wise, H. [Integrated Concepts and Research Corporation - Huntsville, AL

    2005-01-01

    The current interest in returning to the Moon and Mars by 2030 makes cost effective and low mass health monitoring sensors essential for spacecraft development. In space, there are many surface measurements that are required to monitor the condition of the spacecraft including: surface temperature, radiation dose, and impact. Through the use of phosphors, these conditions can be monitored. Practical space-based phosphor sensors will depend heavily upon research investigating the resistance of phosphors to ionizing radiation and the ability to anneal or self-heal from damage caused by ionizing radiation. The cathodoluminescence (CL) testing was performed using the low energy electron system located at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. For the materials tested, several interesting results were observed. For most materials, increases in both beam energy and current density improved the CL fluorescence yield. It was also noted that YAG:Nd,Ce has the greatest near infrared intensity for any of the tested materials. The evaluation of dopant concentration in YPO{sub 4}:Nd showed minimal differences in spectral shape and intensity. While the total electron dose was small, the intention was to maximize the number of irradiated materials.

  20. Diamonds in meteorites – Raman mapping and cathodoluminescence studies

    Directory of Open Access Journals (Sweden)

    A.T. Karczemska

    2010-11-01

    Full Text Available diversity among the diversity of other extraterrestrial carbon phases. The main subject of research shown here are example meteorites consisting diamonds: ureilites DaG 868 and Dho 3013. Results are compared with previous investigations. Diamonds exist in many different meteorites, interplanetary dust particles (IDPs and in comets dust. Origin of different diamonds is still debated among the scientists, two main possibilities are taken into consideration CVD process or shock metamorphism. Understanding laboratory techniques of manufacturing diamond helps in understanding the processes taking place in the Space. From the other side, the new findings and discoveries give the new insight to material science and laboratory techniques.Design/methodology/approach: The samples were examined with different methods, the most investigations presented here are Raman Mapping and Cathodoluminescence (CL.Findings: Diamonds have been found in different samples with different shock stages. It means that not all diamonds in urelites could have shock origin. Diamonds from examined samples show high diversity, they exist in different sizes, from nanodiamonds to micrometer sizes diamonds and in different polytypes. Shifts of Raman diamond peaks indicates this.Research limitations/implications: Results show the possibilities of creating the new diamond-based materials similar to those found in meteorites. Diamond polytypes are not well characterized yet and could give some surprises for materials science. For future research it would be interesting to apply more methods such as X-ray diffraction or HRTEM.Originality/value: SEM+BSE+EDS+CL results and Raman imaging results of DaG 868 and Dho 1303 ureilites are shown for the first time.

  1. Origin and Characteristics of Blue Light Emission in Solid State Cathodoluminescence of MEH-PPV

    Institute of Scientific and Technical Information of China (English)

    QU Chong; XU Zheng; TENG Feng; QIAN Lei; YU Wen-Ge; QUAN Shan-Yu; XU Xu-Rong

    2004-01-01

    Based on our previous study [Chin. Phys. Lett. 20 (2003) 1144] on the solid-state cathodoluminescence from organic luminescent materials, here we study the origin and characteristics of blue light emission in solid-state cathodoluminescence of Poly [(2-methoxy-5-(2′-ethyl-hexyloxy)phenylene vinyene] (MEH-PPV) and the dependence of each spectral peak on electric field strength. The results demonstrate that the blue spectral shift benefits from field ionization of excitons, and three regions of electric field are found, in which there are pure exciton emission, coexistence of exciton emission and radiative recombination, and pure radiative recombination.

  2. Cathodoluminescence of quartz and feldspar in provenance research

    Science.gov (United States)

    Augustsson, Carita; Reker, Annalena; Scholonek, Christiane

    2013-04-01

    Quartz often dominates in siliciclastic sandstone and feldspar mostly is present. Despite this, the use of quartz and feldspar in provenance research is limited. Feldspar is less stable than both quartz and many other minerals that are used to trace sources rocks, such as zircon and rutile. Nevertheless, particularly quartz and zircon may survive many sedimentary recycling phases. Therefore they do not necessarily give information about first-cycle sources. Hence, the wide occurrence of feldspar and quartz in sedimentary rocks is an excellent condition to trace both first-cycle and multi-cycle sediment sources. The cathodoluminescence (CL) technique enables the consideration of both minerals. We analysed ca. 1000 quartz crystals and ca. 1200 feldspar crystals in ca. 60 samples each for their CL colour spectra to investigate their provenance potential. They originate from different plutonic, volcanic, metamorphic, and pegmatitic rocks. The CL colours of quartz vary from red over violet to different shades of blue and brown. They are due to lattice defects and trace element contents that are caused by different crystallisation conditions and later lattice reorganisation. The corresponding CL spectra are dominated by two apparent intensity peaks at 470-490 nm (blue) and at 600-640 nm (red). Distinctive relative intensity differences in these two peaks occur for (1) quartz of volcanic origin, (2) felsic plutonic and high-temperature metamorphic quartz, and (3) low-temperature metamorphic quartz. Feldspar often luminesces in different shades of blue, green, yellow, and red due to substitution elements. Alkali feldspar usually has a bright blue colour and plagioclase often is green. The corresponding CL spectra are dominated by three apparent intensity peaks at 420-500 nm (blue), 540-570 nm (green) and 690-760 nm (red to infrared). The CL is particularly useful for the distinction of plagioclase from alkali feldspar. Here, a dominance of the peak in green over the peak

  3. FIB-SEM cathodoluminescence tomography: practical and theoretical considerations.

    Science.gov (United States)

    De Winter, D A M; Lebbink, M N; Wiggers De Vries, D F; Post, J A; Drury, M R

    2011-09-01

    Focused ion beam-scanning electron microscope (FIB-SEM) tomography is a powerful application in obtaining three-dimensional (3D) information. The FIB creates a cross section and subsequently removes thin slices. The SEM takes images using secondary or backscattered electrons, or maps every slice using X-rays and/or electron backscatter diffraction patterns. The objective of this study is to assess the possibilities of combining FIB-SEM tomography with cathodoluminescence (CL) imaging. The intensity of CL emission is related to variations in defect or impurity concentrations. A potential problem with FIB-SEM CL tomography is that ion milling may change the defect state of the material and the CL emission. In addition the conventional tilted sample geometry used in FIB-SEM tomography is not compatible with conventional CL detectors. Here we examine the influence of the FIB on CL emission in natural diamond and the feasibility of FIB-SEM CL tomography. A systematic investigation establishes that the ion beam influences CL emission of diamond, with a dependency on both the ion beam and electron beam acceleration voltage. CL emission in natural diamond is enhanced particularly at low ion beam and electron beam voltages. This enhancement of the CL emission can be partly explained by an increase in surface defects induced by ion milling. CL emission enhancement could be used to improve the CL image quality. To conduct FIB-SEM CL tomography, a recently developed novel specimen geometry is adopted to enable sequential ion milling and CL imaging on an untilted sample. We show that CL imaging can be manually combined with FIB-SEM tomography with a modified protocol for 3D microstructure reconstruction. In principle, automated FIB-SEM CL tomography should be feasible, provided that dedicated CL detectors are developed that allow subsequent milling and CL imaging without manual intervention, as the current CL detector needs to be manually retracted before a slice can be milled

  4. Can cathodoluminescence of feldspar be used as provenance indicator?

    Science.gov (United States)

    Scholonek, Christiane; Augustsson, Carita

    2016-05-01

    We have studied feldspar from crystalline rocks for its textural and spectral cathodoluminescence (CL) characteristics with the aim to reveal their provenance potential. We analyzed ca. 60 rock samples of plutonic, volcanic, metamorphic, and pegmatitic origin from different continents and of 16 Ma to 2 Ga age for their feldspar CL textures and ca. 1200 feldspar crystals from these rocks for their CL color spectra. Among the analyzed rocks, igneous feldspar is most commonly zoned, whereby oscillatory zoning can be confirmed to be typical for volcanic plagioclase. The volcanic plagioclase also less commonly contains twin lamellae that are visible in CL light than crystals from other rock types. Alkali feldspar, particularly from igneous and pegmatitic rocks, was noted to be most affected by alteration features, visible as dark spots, lines and irregular areas. The size of all textural features of up to ca. 150 μm, in combination with possible alteration in both the source area and the sedimentary system, makes the CL textures of feldspar possible to use for qualitative provenance research only. We observed alkali feldspar mostly to luminesce in a bluish color and sometimes in red, and plagioclase in green to yellow. The corresponding CL spectra are dominated by three apparent intensity peaks at 440-520 nm (mainly blue), 540-620 nm (mainly green) and 680-740 nm (red to infrared). A dominance of the peak in the green wavelength interval over the blue one for plagioclase makes CL particularly useful for the differentiation of plagioclase from alkali feldspar. An apparent peak position in red to infrared at < 710 nm for plagioclase mainly is present in mafic rocks. Present-day coastal sand from Peru containing feldspar with the red to infrared peak position mainly exceeding 725 nm for northern Peruvian sand and a larger variety for sand from southern Peru illustrates a discriminative effect of different source areas. We conclude that the provenance application

  5. Memory effect and cathodoluminescent properties of YAG:Nd3+ nanoceramics

    Science.gov (United States)

    Orekhova, K. N.; Trofimov, A. N.; Zamoryanskaya, M. V.; Stręk, W.

    2016-06-01

    The cathodoluminescent properties of nanoceramics based on neodymium-doped yttrium-aluminum garnet (YAG:Nd3+) are studied in a wide optical spectral range (from UV to IR). It is shown that the spectral positions of the emission bands of nanoceramics are identical to that of single crystal, but the bands of nanoceramics are broadened by no more than 15% from the half bandwidths of single crystal. The intensity of cathodoluminescence bands in nanoceramics is lower, and the lifetimes of radiative levels are shorter. It is found for the first time that electron-beam irradiation of nanoceramics increases the cathodoluminescence intensity of bands in visible and UV ranges (by two or more times). Preliminary electron beam irradiation of YAG:Nd3+ nanoceramics samples leads to the increase of cathodoluminescence efficiency. Such effect retains for a long time (a year and more) and can be compared to the memory effect. This effect is not observed in single crystal. We propose a model describing this effect in nanoceramics.

  6. Silicon-Vacancy Color Centers in Nanodiamonds: Cathodoluminescence Imaging Marker in the Near Infrared

    OpenAIRE

    Zhang, Huiliang; Aharonovich, Igor; Glenn, David R.; Schalek, R.; Magyar, Andrew P.; Lichtman, Jeff W.; Hu, Evelyn L.; Walsworth, Ronald L.

    2013-01-01

    We demonstrate that nanodiamonds fabricated to incorporate silicon-vacancy (Si-V) color centers provide bright, spectrally narrow, and stable cathodoluminescence (CL) in the near-infrared. Si-V color centers containing nanodiamonds are promising as non-bleaching optical markers for correlated CL and secondary electron microscopy, including applications to nanoscale bioimaging.

  7. Cathodoluminescence investigations on quartz cement in the sandstones of Khabour Formation from Iraqi Kurdistan Region, Northern Iraq

    DEFF Research Database (Denmark)

    Omer, Muhamed Fakhri; Friis, Henrik

    2014-01-01

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic stud...

  8. Cathodoluminescence, reflectivity changes, and accumulation of graphitic carbon during electron beam aging of phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Seager, C.H.; Tallant, D.R.; Warren, W.L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    1997-11-01

    We demonstrate that extended e-beam exposure produces a contaminating overlayer on phosphors whose opacity increases roughly linearly with time. Raman scattering data and optical analysis indicate that this layer is graphitic in nature, arising from the electron-beam-stimulated conversion of hydrocarbons adsorbed from the vacuum ambient. The presence of this contamination optically attenuates emitted cathodoluminescence, prevents many low energy electrons from ever reaching the phosphor grains, and exacerbates surface charging which reduces the arrival energy of electrons above 1.5{endash}2 keV. All of these effects are shown to impact cathodoluminescent output in an important way, but an accurate accounting of their total impact will be required to assess the importance of other degradation mechanisms like enhanced nonradiative electron-hole recombination at surfaces, both carbon and noncarbon related. {copyright} {ital 1997 American Institute of Physics.}

  9. Cathodoluminescence and epitaxy after laser annealing of Cs{sup +}-irradiated {alpha}-quartz

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, P.K. [II. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Gasiorek, S. [II. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Dhar, S. [II. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Lieb, K.P. [II. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Schaaf, P. [II. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)]. E-mail: pschaaf@uni-goettingen.de

    2006-04-30

    In the course of a systematic investigation of dynamic, chemical, and laser-induced solid phase epitaxy of {alpha}-quartz after ion implantation, we have studied epitaxy and cathodoluminescence emission after 250 keV Cs-ion implantation and subsequent pulsed excimer laser treatment in air. Rutherford backscattering channelling analysis showed partial epitaxy for all the laser-irradiated samples; however, no full epitaxy was achieved. The optical properties of these samples were analyzed using cathodoluminescence spectroscopy, giving evidence of five emission bands at 2.42, 2.79, 3.25, 3.65, and 4.30 eV photon energy. Their intensity relation to the laser power and retained Cs-ion fraction are discussed and the present results will be compared with those obtained after chemical and dynamic epitaxy of quartz after alkali-ion, Ge, and Ba implantation.

  10. Electroluminescence and cathodoluminescence from polyethylene and polypropylene films: Spectra reconstruction from elementary components and underlying mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, B. [Université de Toulouse, UPS, INP, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, F-31062 Toulouse (France); Teyssedre, G.; Laurent, C. [Université de Toulouse, UPS, INP, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, LAPLACE, F-31062 Toulouse (France)

    2016-01-14

    The mechanisms of electroluminescence from large band gap polymers used as insulation in electric components are still under debate. It becomes important to unravel the underlying physics of the emission because of increasing thermo-electric stress and a possible relationship between electroluminescence and field withstand. We report herein on the cathodoluminescence spectra of polyethylene and polypropylene films as a way to uncover the nature of its contributions to electroluminescence emission. It is shown that spectra from the two materials are structured around four elementary components, each of them being associated with a specific process contributing to the overall emission with different weights depending on excitation conditions and on materials. The cathodoluminescence and electroluminescence spectra of each material are reconstructed from the four spectral components and their relative contribution are discussed. It is shown that electroluminescence from polyethylene and polypropylene has the same origin pointing towards generic mechanisms in both.

  11. Electroluminescence and cathodoluminescence from polyethylene and polypropylene films: Spectra reconstruction from elementary components and underlying mechanisms

    Science.gov (United States)

    Qiao, B.; Teyssedre, G.; Laurent, C.

    2016-01-01

    The mechanisms of electroluminescence from large band gap polymers used as insulation in electric components are still under debate. It becomes important to unravel the underlying physics of the emission because of increasing thermo-electric stress and a possible relationship between electroluminescence and field withstand. We report herein on the cathodoluminescence spectra of polyethylene and polypropylene films as a way to uncover the nature of its contributions to electroluminescence emission. It is shown that spectra from the two materials are structured around four elementary components, each of them being associated with a specific process contributing to the overall emission with different weights depending on excitation conditions and on materials. The cathodoluminescence and electroluminescence spectra of each material are reconstructed from the four spectral components and their relative contribution are discussed. It is shown that electroluminescence from polyethylene and polypropylene has the same origin pointing towards generic mechanisms in both.

  12. A nano-graphite cold cathode for an energy-efficient cathodoluminescent light source

    Directory of Open Access Journals (Sweden)

    Alexander N. Obraztsov

    2013-08-01

    Full Text Available The development of new types of light sources is necessary in order to meet the growing demands of consumers and to ensure an efficient use of energy. The cathodoluminescence process is still under-exploited for light generation because of the lack of cathodes suitable for the energy-efficient production of electron beams and appropriate phosphor materials. In this paper we propose a nano-graphite film material as a highly efficient cold cathode, which is able to produce high intensity electron beams without energy consumption. The nano-graphite film material was produced by using chemical vapor deposition techniques. Prototypes of cathodoluminescent lamp devices with a construction optimized for the usage of nano-graphite cold cathodes were developed, manufactured and tested. The results indicate prospective advantages of this type of lamp and the possibility to provide advanced power efficiency as well as enhanced spectral and other characteristics.

  13. Syn- and postkinematic cement textures in fractured carbonate rocks: Insights from advanced cathodoluminescence imaging

    Science.gov (United States)

    Ukar, Estibalitz; Laubach, Stephen E.

    2016-10-01

    In calcite and dolomite deposits in fractures, transmitted light and optical cathodoluminescence methods detect crack-seal texture in some fractures, but scanning electron microscope-based cathodoluminescence (SEM-CL) combined with secondary-electron images and element maps, reveals crack-seal and cement growth textures where previous SEM-CL imaging methods found massive or featureless deposits. In a range of fractured carbonate rocks, patterns and textures of calcite and dolomite cements precipitated during and after fracture growth resemble complex accumulation patterns found in quartz in sandstone fractures, suggesting that some apparent differences between carbonate mineral and quartz deposits in fractures reflect the limits of previous imaging methods. Advances in delineating textures in widespread carbonate mineral deposits in fractures provide evidence for growth and occlusion of fracture porosity.

  14. Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence

    OpenAIRE

    Pozina, Galia; Ciechonski, Rafal; Bi, Zhaoxia; SAMUELSON, Lars; Monemar, Bo

    2015-01-01

    Todays energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At lo...

  15. Synthesis and cathodoluminescence characterization of ZrO{sub 2}:Er{sup 3+} films

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Hernández, A.; Guzmán-Mendoza, J. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Unidad Legaria, Av. Legaria 694, 11500 México, D. F. (Mexico); Rivera-Montalvo, T., E-mail: trivera@ipn.mx [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Unidad Legaria, Av. Legaria 694, 11500 México, D. F. (Mexico); Sánchez-Guzmán, D.; Guzmán-Olguín, J.C. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Unidad Legaria, Av. Legaria 694, 11500 México, D. F. (Mexico); García-Hipólito, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, 04510 México, D. F. (Mexico); Falcony, C. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07000 México, D.F., México (Mexico)

    2014-09-15

    Trivalent erbium doped zirconium oxide films were deposited by the ultrasonic spray pyrolysis technique. Films were deposited using zirconium tetrachloride octahydrate (ZrCl{sub 4}O·8H{sub 2}O) and erbium nitrate hexahydrate ((NO{sub 3}){sub 3}Er·6H{sub 2}O) as precursors and deionized water as solvent. The dopant concentrations in the spray solution were 1, 3, 5, 10 and 15 at% in ratio to zirconium content. The films were deposited on corning glass substrates at different temperatures from 400 up to 550 °C. Films deposited at temperatures lower than 400 °C were amorphous, however, as substrate temperatures are increased, the ZrO{sub 2} films presented a better crystallinity and showed a tetragonal phase. Cathodoluminescence (CL) emission spectra showed bands centred at 524, 544 and 655 nm associated with the electronic transition of Er{sup 3+}. - Highlights: • The films of ZrO{sub 2}:Er{sup 3+} were obtained by spray pyrolysis. • Emission spectra of ZrO{sub 2}:Er{sup 3+} films were reported. • Cathodoluminescence of ZrO{sub 2}:Er{sup 3+} films was analyzed. • Cathodoluminescence of ZrO{sub 2}:Er{sup 3+} films showed strong dependence on substrate temperature and electron voltage.

  16. Cathodoluminescence (CL) features of the Anatolian agates, hydrothermally deposited in different volcanic hosts from Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Hatipoglu, Murat, E-mail: murat.hatipoglu@deu.edu.t [Dokuz Eylul University, IMYO, Izmir Multidisciplinary Vocational School, Gemmology and Jewellery Programme, TR-35380 Buca-Izmir (Turkey); Ajo, David [Institute of Inorganic Chemistry and Surfaces, CNR, Corso Stati Uniti 4, I-35127 Padova (Italy); SMATCH (Scientific Methodologies Applied to Cultural Heritage), Largo Ugo Bartolomei 5, I-00136 Rome (Italy); Sezai Kirikoglu, M. [Istanbul Technical University, Faculty of Mine, Department of Geological Engineering, TR-34469 Maslak-Istanbul (Turkey)

    2011-06-15

    Two different types of multi-colored gem-quality agate samples were investigated. They are both found in the same area in the Cubuk-Ankara region of Turkey although the first group is morphologically and geologically distinct from the second, being nodular-shaped agates occurring in cavity-spaces of a rhyolite host rock with an acidic character. They generally do not have any macroscopic inclusions, but the second group of rather block-shaped agates occurs in the fracture-spaces of an andesite host rock with a more neutral character, i.e. of lower free silica content, and they may display pseudomorphic bar-like macroscopic inclusions. Cathodoluminescence results at room temperature were obtained using measurements with alternating current (AC) (at energies of 14 and 24 keV) as well as direct current (DC) (at 14 keV energy), and they display remarkably different patterns between the two types of agates. It reveals a relation between the CL emissions and the presence of some transition metal elements. It is obvious that all trace elements do not play a direct role. Gaussian fitting of the cathodoluminescence AC experimental data at 14 keV energy obtained from the agates of rhyolite host indicates that there are three major spectral emissions, the dominant one being in the longer-visible wavelength region (red region) at about 690 nm. Additionally, two lesser emission lines occur in the middle-visible wavelength region (yellow region) at about 590 nm, and in the smaller-visible wavelength region (blue region) at about 430 nm. In spite of these, the same data from the agates of andesite host indicate that there is only one remarkable spectral emission which is in the in the middle-visible wavelength region (yellow region) at about 590 nm. On the other hand, Gaussian fitting of the cathodoluminescence AC experimental data at 24 keV energy obtained from the agates of rhyolite host indicates that these initial spectral emissions shift from the red and yellow regions to

  17. Cathodoluminescence studies of GaAs nano-wires grown on shallow-trench-patterned Si

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ling; Fan, Wen-Chung; Ku, Jui-Tai; Chang, Wen-Hao; Chen, Wei-Kuo; Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan (China); Ko, Chih-Hsin; Wu, Cheng-Hsien; Lin, You-Ru; Wann, Clement H [Taiwan Semiconductor Manufacturing Co., Ltd, Hsinchu 300, Taiwan (China); Hsu, Chao-Wei; Chen, Yung-Feng; Su, Yan-Kuin, E-mail: acceptor.ep89g@nctu.edu.tw, E-mail: wuchingchou@mail.nctu.edu.tw [Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2010-11-19

    The optical properties of GaAs nano-wires grown on shallow-trench-patterned Si(001) substrates were investigated by cathodoluminescence. The results showed that when the trench width ranges from 80 to 100 nm, the emission efficiency of GaAs can be enhanced and is stronger than that of a homogeneously grown epilayer. The suppression of non-radiative centers is attributed to the trapping of both threading dislocations and planar defects at the trench sidewalls. This approach demonstrates the feasibility of growing nano-scaled GaAs-based optoelectronic devices on Si substrates.

  18. LabVIEW-based control and data acquisition system for cathodoluminescence experiments.

    Science.gov (United States)

    Bok, J; Schauer, P

    2011-11-01

    Computer automation of cathodoluminescence (CL) experiments using equipment developed in our laboratory is described. The equipment provides various experiments for CL efficiency, CL spectra, and CL time response studies. The automation was realized utilizing the graphical programming environment LabVIEW. The developed application software with procedures for equipment control and data acquisition during various CL experiments is presented. As the measured CL data are distorted by technical limitations of the equipment, such as equipment spectral sensitivity and time response, data correction algorithms were incorporated into the procedures. Some examples of measured data corrections are presented.

  19. Cathodoluminescent and electrical properties of an individual ZnO nanowire with oxygen vacancies

    Institute of Scientific and Technical Information of China (English)

    He Xiao-Bo; Yang Tian-Zhong; Cai Jin-Ming; Zhang Chen-Dong; Guo Hai-Ming; Shi Dong-Xia; Shen Cheng-Min; Gao Hong-Jun

    2008-01-01

    A single ZnO nanowire with intrinsic oxygen vacancies is utilized to fabricate four-contact device with focus ion beam lithography technique.Cathodoluminescent spectra indicate strong near-UV and green emission at both room temperature and low temperatures.Experimented measurement shows the temperature-dependent conductivity of the ZnO nanowire at low temperatures(below 100 K).The further theoretical analysis confirms that weak localization plays an important role in the electrical transport,which is attributed to the surface states induced by plenty of oxygen vacancies in ZnO nanowire.

  20. Transient demonstration of exciton behaviours in solid state cathodoluminescence under different driving voltage

    Institute of Scientific and Technical Information of China (English)

    Zhang Fu-Jun; Zhao Su-Ling; Xu Zheng; Huang Jin-Zhao; Xu Xu-Rong

    2007-01-01

    In the solid state cathodoluminescence (SSCL), organic materials were excited by hot electrons accelerated in silicon oxide (SiO2) layer under alternating current (AC). In this paper exciton behaviours were analysed by using transient spectra under different driving voltages. The threshold voltages of SSCL and exciton ionization were obtained from the transient spectra. The recombination radiation occurred when the driving voltage went beyond the threshold voltage of exciton ionization. Prom the transient spectrum of two kinds of luminescence (exciton emission and recombination radiation), it was demonstrated that recombination radiation should benefit from the exciton ionization.

  1. Combinatorial Ion Synthesis and Cathodoluminescence Analyses of Materials Libraries on Thermally Grown SiO2

    Institute of Scientific and Technical Information of China (English)

    Chang-Ming Chen; H.C.Pan; D.Z. Zhu; J.Hu; M.Q.Li

    2000-01-01

    We first report a method combining ion implantationand physical masking to generate material libraries of various ion-implanted samples. This approach offers rapid synthesis of samples with potential new compounds formed in the matrix, which may have specific luminescent properties. The depthresolved cathodoluminescence (CL) measurements, accompanied with Rutherford backscattering spectrometry (RBS) and proton elastic scattering (PES) revealed some specific optical properties in the samples correlated with implanted ion distributions. These measurements are capable of nondestructively and rapidly characterizing the composition and the inhomogeneity of the combinatorial film libraries, which may determine their physical properties.

  2. Cathodoluminescence zoning and minor elements in forsterites from the Murchison (C2) and Allende (C3V) carbonaceous chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Steele, I.M.; Smith, J.V.; Skirius, C. (Chicago Univ., IL (USA). Dept. of Geophysical Sciences)

    1985-01-24

    The authors have applied the cathodoluminescence technique to look for textural features of olivine in carbonaceous meteorites relevant to the unresolved dispute over its origin, whether from a vapour or a liquid. The cathodoluminescence photographs of forsterite grains in Murchison (C2) and Allende (C3) meteorites reveal a blue core (inclusion-free) with planar boundaries to a red or dark rim. Also performed are high-precision electron microprobe analyses revealing in these forsterites unusually large amounts of the 'minor' elements Al, Ti and Ca in the blue cores, suggesting formation by crystallization at high temperatures from a source rich in these metals.

  3. Cathodoluminescence and Raman Spectromicroscopy of Forsterite in Tagish Lake Meteorite: Implications for Astromineralogy

    Directory of Open Access Journals (Sweden)

    Arnold Gucsik

    2016-01-01

    Full Text Available The Tagish Lake meteorite is CI/CM2 chondrite, which fell by a fireball event in January 2000. This study emphasizes the cathodoluminescence (CL and Raman spectroscopical properties of the Tagish Lake meteorite in order to classify the meteoritic forsterite and its relation to the crystallization processes in a parent body. The CL-zoning of Tagish Lake meteorite records the thermal history of chondrules and terrestrial weathering. Only the unweathered olivine is forsterite, which is CL-active. The variation of luminescence in chondrules of Tagish Lake meteorite implies chemical inhomogeneity due to low-grade thermal metamorphism. The blue emission center in forsterite due to crystal lattice defect is proposed as being caused by rapid cooling during the primary crystallization and relatively low-temperature thermal metamorphism on the parent body of Tagish Lake meteorite. This is in a good agreement with the micro-Raman spectroscopical data. A combination of cathodoluminescence and micro-Raman spectroscopies shows some potentials in study of the asteroidal processes of parent bodies in solar system.

  4. The role of transition radiation in cathodoluminescence imaging and spectroscopy of thin-foils

    Energy Technology Data Exchange (ETDEWEB)

    Mendis, B.G. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Howkins, A. [Experimental Techniques Centre, Brunel University, Uxbridge UB8 3PH (United Kingdom); Stowe, D. [Gatan UK, 25 Nuffield Way, Abingdon, Oxfordshire OX14 1RL (United Kingdom); Major, J.D.; Durose, K. [Stephenson Institute for Renewable Energy, University of Liverpool, Liverpool L69 7ZF (United Kingdom)

    2016-08-15

    There is renewed interest in cathodoluminescence (CL) in the transmission electron microscope, since it can be combined with low energy loss spectroscopy measurements and can also be used to probe defects, such as grain boundaries and dislocations, at high spatial resolution. Transition radiation (TR), which is emitted when the incident electron crosses the vacuum-specimen interface, is however an important artefact that has received very little attention. The importance of TR is demonstrated on a wedge shaped CdTe specimen of varying thickness. For small specimen thicknesses (<250 nm) grain boundaries are not visible in the panchromatic CL image. Grain boundary contrast is produced by electron–hole recombination within the foil, and a large fraction of that light is lost to multiple-beam interference, so that thicker specimens are required before the grain boundary signal is above the TR background. This is undesirable for high spatial resolution. Furthermore, the CL spectrum contains additional features due to TR which are not part of the ‘bulk’ specimen. Strategies to minimise the effects of TR are also discussed. - Highlights: • Grain boundary cathodoluminescence contrast is anomalously low in the TEM. • This is due to transition radiation (TR) generated at the vacuum-specimen interface. • Thick foils are required for the recombination luminescence to suppress TR. • This is undesirable for high spatial resolution analysis of grain boundaries. • Strategies to minimise TR are also discussed.

  5. Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Engelsen, Daniel den; Harris, Paul G.; Ireland, Terry G., E-mail: terry.ireland@brunel.ac.uk; Fern, George R.; Silver, Jack

    2015-10-15

    Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. - Highlights: • Contrast enhancement are observed in secondary electron and cathodoluminescent images of phosphor particles sitting on top of others. • Backscattered electrons largely explain the observed contrast enhancement. • After glow effects in CL-micrographs of phosphors enable the determination of decay times. • Phosphor saturation can be used to determine the decay time of individual spectral transitions.

  6. Cathodoluminescence study of SnO{sub 2} powders aimed for gas sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Korotcenkov, G. [Technical University of Moldova, Chisinau (Moldova, Republic of)]. E-mail: ghkoro@yahoo.com; Nazarov, M. [Technical University of Moldova, Chisinau (Moldova, Republic of); Zamoryanskaya, M.V. [A.F. Ioffe Physical Technical Institute, RAS, St. Petersburg, Russia (Russian Federation); Ivanov, M. [Technical University of Moldova, Chisinau (Moldova, Republic of); Cirera, A. [EME/CERMAE. Dep. Elect., University of Barcelona, Barcelona (Spain); Shimanoe, K. [Kyushu University, Kasuga-shi, Fukuoka (Japan)

    2006-06-15

    In this paper we report on cathodoluminescence (CL) spectra of SnO{sub 2} powders, synthesized using the wet chemical route. The analysis of influence of the modes of calcination (T {sub an}-450-800 deg. C), and doping by both Pd and Pt (0.01-10.0 wt.%) on CL spectra was made. It was found that the measurement of CL spectra could be an effective research method of nanostructured metal oxides, aimed for gas sensor applications. It was established that in nanocrystalline SnO{sub 2} the same system of energy levels, associated with radiative recombination, as in single crystalline and polycrystalline SnO{sub 2}, is retained. It was found that doping by both Pd and Pt modifies the structural properties of SnO{sub 2} grains. Also, there is an optimum doping; near 0.1-0.2 wt.%, at which a maximum intensity of cathodoluminescence is reached. It was concluded that for low concentrations of both Pd and Pt additives in SnO{sub 2} an improvement of the material's crystal structure is promoted, and is associated with a decrease in the non-radiating recombination rate.

  7. Cathodoluminescence microscopy of hydrothermal and flux grown ZnO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Urbieta, A.; Fernandez, P.; Piqueras, J.; Hardalov, Ch. [Departamento de Fisica de Materiales, Facultad de Fisicas, Universidad Complutense, Madrid (Spain); Sekiguchi, T. [Nanomaterials Laboratory, National Institute for Materials Science, Sengen, Tsukuba (Japan)

    2001-10-07

    Bulk ZnO single crystals grown by the hydrothermal and flux methods have been characterized by steady-state and time resolved cathodoluminescence measurements performed on the different crystalline faces. A shift of the peak near band edge towards lower energies is observed in spectra recorded with increasing delay times. This behaviour is often observed in the etch pit regions in alkali flux grown crystals, which suggests the presence of a band related to dislocations or to the point defects surrounding the dislocations. In the low-energy region, cathodoluminescence spectra show that the relative intensity of the different components of the deep level band also depends on the atomic structure of the face under study. This complex behaviour is clearly revealed from the time resolved spectra. The differences observed are attributed to the nature of the defects present in each face and, in particular, to different impurity incorporation processes that could be mainly controlled by the atomic configuration and polarity of the planes. (author)

  8. Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence

    Science.gov (United States)

    Pozina, Galia; Ciechonski, Rafal; Bi, Zhaoxia; Samuelson, Lars; Monemar, Bo

    2015-12-01

    Today's energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At low current, the dislocations are inactive in carrier recombination due to local potentials, but these potentials are screened by carriers at higher injection levels. In CL images, this corresponds to the increase of the dark contrast around dislocations with the injection (excitation) density and can be linked with droop related to the threading dislocations. Our data indicate that reduction of droop in the future efficient white LED can be achieved via a drastic reduction of the dislocation density by using, for example, bulk native substrates.

  9. Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Pozina, Galia [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Ciechonski, Rafal [GLO AB, Scheelevägen 22, SE-22363 Lund (Sweden); Bi, Zhaoxia [Solid State Physics, Lund University, Box 118, SE-22100 Lund (Sweden); Samuelson, Lars [GLO AB, Scheelevägen 22, SE-22363 Lund (Sweden); Solid State Physics, Lund University, Box 118, SE-22100 Lund (Sweden); Monemar, Bo [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Solid State Physics, Lund University, Box 118, SE-22100 Lund (Sweden); TokyoUniversity of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

    2015-12-21

    Today's energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At low current, the dislocations are inactive in carrier recombination due to local potentials, but these potentials are screened by carriers at higher injection levels. In CL images, this corresponds to the increase of the dark contrast around dislocations with the injection (excitation) density and can be linked with droop related to the threading dislocations. Our data indicate that reduction of droop in the future efficient white LED can be achieved via a drastic reduction of the dislocation density by using, for example, bulk native substrates.

  10. Spectrum-per-Pixel Cathodoluminescence Imaging of CdTe Thin-Film Bevels

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John; Al-Jassim, Mowafak M.; Burst, James; Guthrey, Harvey L.; Metzger, Wyatt K.

    2016-11-21

    We conduct T=6 K cathodoluminescence (CL) spectrum imaging with a nano-scale electron beam on beveled surfaces of CdTe thin-films at different critical stages of standard CdTe device fabrication. The through-thickness total CL intensity profiles are consistent with a reduction in grain boundary recombination due to the CdCl2 treatment. Color-coded maps of the low-temperature luminescence transition energies reveal that CdTe thin films have remarkably non-uniform opto-electronic properties, which depend strongly on sample processing history. The grain-to-grain S content in the interdiffused CdTe/CdS region is estimated from a sample size of thirty-five grains, and the S content in adjacent grains varies significantly in CdCl2-treated samples. A low-temperature luminescence model is developed to interpret spectral behavior at grain boundaries and grain interiors.

  11. Imaging the Hidden Modes of Ultrathin Plasmonic Strip Antennas by Cathodoluminescence

    KAUST Repository

    Barnard, Edward S.

    2011-10-12

    We perform spectrally resolved cathodoluminescence (CL) imaging nanoscopy using a 30 keV electron beam to identify the resonant modes of an ultrathin (20 nm), laterally tapered plasmonic Ag nanostrip antenna. We resolve with deep-subwavelength resolution four antenna resonances (resonance orders m = 2-5) that are ascribed to surface plasmon polariton standing waves that are confined on the strip. We map the local density of states on the strip surface and show that it has contributions from symmetric and antisymmetric surface plasmon polariton modes, each with a very different mode index. This work illustrates the power of CL experiments that can visualize hidden modes that for symmetry reasons have been elusive in optical light scattering experiments. © 2011 American Chemical Society.

  12. High-Q band edge mode of plasmonic crystals studied by cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Masahiro; Yamamoto, Naoki, E-mail: nyamamot@phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan)

    2014-02-24

    We have investigated the quality factor (Q-factor) of the band edge modes in the plasmonic crystal by a cathodoluminescence technique. We have found that the Q-factor at the Γ point depends on the terrace width (D)/period (P) ratio of the plasmonic crystal. The finite-difference time-domain methods predict that the band edge mode at D/P = 3/4 has a high-Q-factor (Q ∼ 250 by Palik's permittivity data and Q ∼ 530 by Johnson and Christy's data). The beam-scan spectral images allowed us to visualize the standing surface plasmon polariton waves at the band edge energies, and a high-Q-factor of ∼200 was observed at D/P ∼ 3/4.

  13. High-Q band edge mode of plasmonic crystals studied by cathodoluminescence

    Science.gov (United States)

    Honda, Masahiro; Yamamoto, Naoki

    2014-02-01

    We have investigated the quality factor (Q-factor) of the band edge modes in the plasmonic crystal by a cathodoluminescence technique. We have found that the Q-factor at the Γ point depends on the terrace width (D)/period (P) ratio of the plasmonic crystal. The finite-difference time-domain methods predict that the band edge mode at D/P = 3/4 has a high-Q-factor (Q ˜ 250 by Palik's permittivity data and Q ˜ 530 by Johnson and Christy's data). The beam-scan spectral images allowed us to visualize the standing surface plasmon polariton waves at the band edge energies, and a high-Q-factor of ˜200 was observed at D/P ˜ 3/4.

  14. Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

    Science.gov (United States)

    Hamers, M. F.; Pennock, G. M.; Drury, M. R.

    2016-11-01

    The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

  15. Cathodoluminescence characterization of polystyrene-BaZrO3 hybrid composites

    Science.gov (United States)

    Savchyn, V. P.; Popov, A. I.; Aksimentyeva, O. I.; Klym, H.; Horbenko, Yu. Yu.; Serga, V.; Moskina, A.; Karbovnyk, I.

    2016-07-01

    The radiation properties and the electronic structure of hybrid composites based on suspension polystyrene (PS) and nanocrystals of BaZrO3 (BZO) (d < 50 nm) have been studied using luminescent spectroscopy and x-ray analysis. A strong cathodoluminescence (CL) in BZO-nanocrystals is observed in temperature range 80-293 K. It is modified in BZO-PS composites: both the low- and a high-energy bands (near 4 eV) appear, together with a significant reduction in the CL intensity. A decrease of the lattice parameter a for BZO phase in the composite and the modification of CL spectra indicate for changes in the nanocrystalline structure induced by the polymer.

  16. Optical Defect in GaN-Based Laser Diodes Detected by Cathodoluminescence

    Institute of Scientific and Technical Information of China (English)

    ZHAO Lu-Bing; WU Jie-Jun; XU Ke; BAO Sui; YANG Zhi-Jian; PAN Yao-Bo; HU Xiao-Dong; ZHANG Guo-Yi

    2008-01-01

    @@ GaN-based laser diodes (LDs) with 399 nm wavelength are grown on sapphire substrates by metal organic chemical vapour deposition (MOCVD).Electroluminescence spectra of the fabricated LDs show that the LDs from some grown wafers failed to emit laser.The SEM and XRD results show the similar surface morphology and interface qualities of multi quantum wells (MQWs) and super-lattices between LDs that succeed and fail to emit laser.However, the cathodoluminescence (CL) measurements reveal a kind of optical defect rather than structural defect in un-emitted LDs.Further depth-dependent CL imaging observation indicates that such optical defects originate from the MQWs to the surface of LDs as a non-irradiative recombination centre that should cause the failure of laser emitting of LDs.

  17. Excitation and Imaging of Resonant Optical Modes of Au Triangular Nano-Antennas Using Cathodoluminescence Spectroscopy

    CERN Document Server

    Kumar, Anil; Mabon, James C; Chow, Edmond; Fang, Nicholas X

    2010-01-01

    Cathodoluminescence (CL) imaging spectroscopy is an important technique to understand resonant behavior of optical nanoantennas. We report high-resolution CL spectroscopy of triangular gold nanoantennas designed with near-vacuum effective index and very small metal-substrate interface. This design helped in addressing issues related to background luminescence and shifting of dipole modes beyond visible spectrum. Spatial and spectral investigations of various plasmonic modes are reported. Out-of-plane dipole modes excited with vertically illuminated electron beam showed high-contrast tip illumination in panchromatic imaging. By tilting the nanostructures during fabrication, in-plane dipole modes of antennas were excited. Finite-difference time-domain simulations for electron and optical excitations of different modes showed excellent agreement with experimental results. Our approach of efficiently exciting antenna modes by using low index substrates is confirmed both with experiments and numerical simulations....

  18. Cathodoluminescence microscopy and spectroscopy of micro- and nanodiamonds: an implication for laboratory astrophysics.

    Science.gov (United States)

    Gucsik, Arnold; Nishido, Hirotsugu; Ninagawa, Kiyotaka; Ott, Ulrich; Tsuchiyama, Akira; Kayama, Masahiro; Simonia, Irakli; Boudou, Jean-Paul

    2012-12-01

    Color centers in selected micro- and nanodiamond samples were investigated by cathodoluminescence (CL) microscopy and spectroscopy at 298 K [room temperature (RT)] and 77 K [liquid-nitrogen temperature (LNT)] to assess the value of the technique for astrophysics. Nanodiamonds from meteorites were compared with synthetic diamonds made with different processes involving distinct synthesis mechanisms (chemical vapor deposition, static high pressure high temperature, detonation). A CL emission peak centered at around 540 nm at 77 K was observed in almost all of the selected diamond samples and is assigned to the dislocation defect with nitrogen atoms. Additional peaks were identified at 387 and 452 nm, which are related to the vacancy defect. In general, peak intensity at LNT at the samples was increased in comparison to RT. The results indicate a clear temperature-dependence of the spectroscopic properties of diamond. This suggests the method is a useful tool in laboratory astrophysics.

  19. Solvothermal route to S-deficient CoS nanoplates and their cathodoluminescence and magnetic properties.

    Science.gov (United States)

    Lei, M; Fu, X L; Yang, H J; Wang, Y G; Zhang, Y B; Li, P G

    2012-03-01

    A facile solvothermal method was developed to fabricate CoS nanoplates using ethylenediamine as solvent. The microstructure characterizations indicate that the CoS nanoplates have well-crystalline hexagonal phase and regular hexagonal or pentagonal shape. The XPS and ICP-AES measurements confirm the chemical composition of nanoplates is S-deficient CoS0.921. Cathodoluminescence spectra of both a large area of the nanoplates and individual nanoplate show broad emission bands centered at 615 nm. Magnetic measurements including magnetization dependence of temperature and magnetic hysteresis loops reveals that the CoS nanoplates exhibit room-temperature ferromagnetic behavior. It is found that intrinsic point defects mainly as V(s), Co(i) and/or the complex defects of V(s) and Co(i) should be responsible for both the broad emission band and the unique ferromagnetism.

  20. Solid solution, phase separation, and cathodoluminescence of GaP-ZnS nanostructures.

    Science.gov (United States)

    Liu, Baodan; Bando, Yoshio; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri; Jiang, Xin

    2013-09-25

    Quaternary solid-solution nanowires made of GaP and ZnS have been synthesized through well-designed synthetic routines. The as-synthesized GaP-ZnS solid-solution nanowires exhibit decent crystallinity with the GaP phase as the host, while a large amount of twin structural defects are observed in ZnS-rich nanowires. Cathodoluminescence studies showed that GaP-rich solid-solution nanowires have a strong visible emission centered at 600 nm and the ZnS-rich solid-solution nanowires exhibited a weak emission peak in the UV range and a broad band in the range 400-600 nm. The formation mechanism, processes, and optical emissions of GaP-ZnS solid-solution nanowires were discussed in detail.

  1. New Data On The Cathodoluminescence Of White Marbles: Interpretation Of Peaks And Relationships To Weathering

    Science.gov (United States)

    Garcia-Guinea, J.; Crespo-Feo, E.; Correcher, V.; Iordanidis, A.; Charalampides, G.; Karamitrou-Mentessidi, G.

    This work focus on the Thermoluminescence (TL), the Spatially Resolved Spectral Cathodoluminescence (CL) and Raman spectroscopy (Raman) of white marble specimens collected from the archaeological park of Aiani (Greece) and from patterns of Iceland calcite and Macael marble for comparison purposes. The spectra CL were measured with a high sensitivity cathodoluminescence spectrometer MonoCL3 of Gatan (UK) attached to an FEI-ESEM microscope (CL-ESEM). The experimental set of spectra CL curves of Aiani white marbles suggest that the blue band is more resistant to weathering in comparison with the red band which drops down easily under weathering. The comparison among CL spectra of CaCO3 patterns give a slight difference between the small 330 nm peak, detected in marble and not observed in the monocrystal pattern of Iceland calcite. The Backscattering Electron Dispersed (BSED) images of the white marble are similar to the CL monochromatic plots at 330 nm which highlight the surfaces with remarkable clarity, suggesting a CL emission-defect associated to the marble crystal interfaces, such as protons or hydroxyls. Conversely, the 395 nm monochromatic mapping depicts a CL image emitting from bulk and not from interfaces attributable to point defects or cationic activators in Ca2+ positions. The blue band of the spectra luminescence of marble is composed by several peaks associated to very different types of luminescent defects. This statement is not inconsequential since in archaeological TL dating of marbles the regenerated luminescence in the blue region of the spectrum is a serious difficulty and further research on this topic is necessary.

  2. Cathodoluminescence of Cr-doped diamond-like carbon film by filtered cathodic vacuum arc plasma

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Meng-Wen; Jao, Jui-Yun [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Lin, Chun-Chun; Hsieh, Wei-Jen; Yang, Yu-Hsiang [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 300, Taiwan (China); Cheng, Li-Shin; Shieu, F.S. [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Shih, Han C., E-mail: hcshih@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 300, Taiwan (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, 55 Hwa Kang Road, Yang Ming Shan, Taipei 111, Taiwan (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The formation of the DLC:Cr films dependent on the flow rates of C{sub 2}H{sub 2}/Ar have been achieved in our FCVA plasma. Black-Right-Pointing-Pointer The amorphous DLC:Cr have high sp{sup 2} content can be completely converted to nanocrystalline Cr{sub 3}C{sub 2}. Black-Right-Pointing-Pointer The effect of doping with Cr is apparently to change the band structure of the DLC and its consequent cathodoluminescence property. - Abstract: Cr doped diamond-like carbon (DLC:Cr) film was synthesized in various flow rates of C{sub 2}H{sub 2}/Ar under a substrate voltage of -50 V at 500 Degree-Sign C by a filtered cathodic vacuum arc plasma. This work has found that the structure of the films was correlated to the flow rate of C{sub 2}H{sub 2}/Ar but the luminescence properties are similar. The cathodoluminescence spectra of DLC:Cr films obtained at 1.9-2.4 eV verifies that the luminescence from the films is in the visible region. The incorporation of Cr into the carbon network results in red emission shifted to 1.99 eV and the orange emission (2.03 eV) also appeared due to the transitions between chromium-related electron levels and {sigma}* states. The peak at 2.10 eV may result from the defects of the structures in DLC:Cr films.

  3. Cathodoluminescence and Raman characteristics of CaSO{sub 4}:Tm{sup 3+}, Cu phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Ekdal, E. [Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir (Turkey); Guinea, J. Garcia [MuseoNacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Kelemen, A. [Centre for Energy Research, Radiation Safety Laboratory, P.O. Box 49, H-1121 Budapest (Hungary); Ayvacikli, M. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Canimoglu, A. [Nigde University, Faculty of Arts and Sciences, Department of Physics, Nigde (Turkey); Jorge, A. [MuseoNacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Karali, T. [Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir (Turkey); Can, N., E-mail: cannurdogan@yahoomail.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Physics Department, Jazan University, P.O. Box 114, 45142 Jazan (Saudi Arabia)

    2015-05-15

    The physical characterization and phosphor emission spectra are presented for CaSO{sub 4} doped with Tm and Cu. All spectral wavelengths are related to electronic transitions of Tm{sup 3+} ions. The powder X-ray diffraction pattern showed that the compound exhibits orthorhombic structure and all reflections were indexed without any other secondary impurity phases. Chemical and structural properties of the samples have been characterized by means of Raman spectroscopy and environmental scanning electron microscope (ESEM) with an attached X-ray energy dispersive system (EDS). Group frequencies concept is essential point to the interpretation of the bands due to the main SO{sub 4} vibrational units and these displayed main characteristic intensive Raman bands including typical strong intensity at 1016 cm{sup −1} that corresponds to ν{sub 1}SO{sub 4} vibrational mode. From the spatially-resolved cathodoluminescence (CL) spectrum, main emission bands of Tm{sup 3+} centered at 346, 362, and 452 nm, due to the respective transitions of {sup 3}P{sub 0}→{sup 3}H{sub 4}, {sup 1}D{sub 2}→{sup 3}H{sub 6}, {sup 1}D{sub 2}→{sup 3}F{sub 4} were clearly identified. The study is novel as no such CL-ESEM data are available for this doped compound. - Highlights: • Characteristic and cathodoluminescence properties of CaSO{sub 4}:Tm{sup 3+}, Cu have been investigated. • Several sharp and strong CL emission bands due to rare earth ion were observed for rare earth doped sample. • The nature and limitation of the interaction between CaSO{sub 4} and the activator ions were discussed.

  4. Cathodoluminescence zoning and minor elements in forsterites from the Murchison (C2) and Allende (C3V) carbonaceous chondrites

    Science.gov (United States)

    Steele, I. M.; Smith, J. V.; Skirius, C.

    1985-01-01

    Cathodoluminescence has been applied to look for textural features of olivine in carbonaceous meteorites relevant to the unresolved dispute over the origin of the olivine, whether from a vapor or a liquid. Cathodoluminescence photographs of forsterite grains in Murchison (C2) and Allende (C3) meteorites presented here reveal a blue core with planar boundaries to a red or dark rim. High-precision electron microprobe analyses have been performed which reveal unusually large amounts of the 'minor' elements Al, Ti, and Ca in the blue cores of these forsterites, suggesting formation by crystallization at high temperatures from a source rich in these metals. Following conclusions drawn from previous analyses of olivine in meteorites, it is argued that the minor element signature should be able to characterize olivines in micrometeorites and in deep-sea particles.

  5. Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers

    Science.gov (United States)

    Haring, Martijn T.; Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Voortman, Lenard M.; Kruit, Pieter; Hoogenboom, Jacob P.

    2017-01-01

    In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample. PMID:28252673

  6. Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers

    Science.gov (United States)

    Haring, Martijn T.; Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Voortman, Lenard M.; Kruit, Pieter; Hoogenboom, Jacob P.

    2017-03-01

    In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample.

  7. Characterization of kesterite thin films fabricated by rapid thermal processing of stacked elemental layers using spatially resolved cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Künecke, Ulrike; Hetzner, Christina; Möckel, Stefan [Materials Department 6, University of Erlangen-Nürnberg (FAU), Martensstr, 7, D-91058 Erlangen (Germany); Yoo, Hyesun; Hock, Rainer [Crystallography and Structure Physics, University of Erlangen-Nürnberg (FAU), Staudtstr, 3, 91058 Erlangen (Germany); Wellmann, Peter, E-mail: peter.wellmann@fau.de [Materials Department 6, University of Erlangen-Nürnberg (FAU), Martensstr, 7, D-91058 Erlangen (Germany)

    2015-05-01

    We report on the microstructure analysis of kesterite (Cu{sub 2}ZnSnSe{sub 4}) layers from rapid thermal processing of sequential elemental layers by spatially resolved cathodoluminescence in a scanning electron microscope. Energy dispersive X-ray fluorescence, X-ray diffraction and Raman spectroscopy were carried out for the validation of the findings. Special emphasis is put on the discussion of the occurrence of the secondary phases Cu{sub 2}SnSe{sub 3}, Cu{sub 2}Se, ZnSe and SnSe. - Highlights: • Spectrally resolved cathodoluminescence of Cu{sub 2}ZnSnSe{sub 4} • Material analysis with a μm spatial resolution • Determination of secondary phases Cu{sub 2}SnSe{sub 3}, Cu{sub 2}Se, SnSe and ZnSe.

  8. Properties of Cathodoluminescence for Cryogenic Applications of SiO2-based Space Observatory Optics and Coatings

    Science.gov (United States)

    Evans, Amberly; Dennison, J.R.; Wilson, Gregory; Dekany, Justin; Bowers Charles W.; Meloy, Robert; Heaney, James B.

    2013-01-01

    Disordered thin film SiO2SiOx coatings undergoing electron-beam bombardment exhibit cathodoluminescence, which can produce deleterious stray background light in cryogenic space-based astronomical observatories exposed to high-energy electron fluxes from space plasmas. As future observatory missions push the envelope into more extreme environments and more complex and sensitive detection, a fundamental understanding of the dependencies of this cathodoluminescence becomes critical to meet performance objectives of these advanced space-based observatories. Measurements of absolute radiance and emission spectra as functions of incident electron energy, flux, and power typical of space environments are presented for thin (60-200 nm) SiO2SiOx optical coatings on reflective metal substrates over a range of sample temperatures (40-400 K) and emission wavelengths (260-5000 nm). Luminescent intensity and peak wavelengths of four distinct bands were observed in UVVISNIR emission spectra, ranging from 300 nm to 1000 nm. A simple model is proposed that describes the dependence of cathodoluminescence on irradiation time, incident flux and energy, sample thickness, and temperature.

  9. Forensic discrimination of glass using cathodoluminescence and CIE LAB color coordinates: a feasibility study.

    Science.gov (United States)

    Bell, Suzanne C; Nawrocki, Heidi D; Morris, Keith B

    2009-08-10

    Cathodoluminescence (CL) spectroscopy has been shown to be useful for differentiating typical evidentiary glass samples. CL occurs when a surface is bombarded with an electron beam as in scanning electron microscopy and most of this luminescence is in the visible range. In effect, CL imparts color to colorless evidence and as a result, proven methods of forensic color analysis can be applied. In this work, spectral data dimensions were reduced to three and plotted in the CIE LAB color space. This approach allows for incorporation of uncertainties generated principally by intra-sample variation. NIST glass standards were used for method development and validation while potential case applications were studied with collections of window, consumer, and auto headlamp glasses. Using refractive index as the initial grouping variable, all of the window and consumer glasses were differentiated as were 6 of 10 automobile headlamp glasses. The potential advantages of CL include low cost instrumentation, its non-destructive nature, and ease of operation. The current limitations of CL in this context are the lack of databases and standards and the relatively low resolution of typical CL spectra.

  10. Three-dimensional cathodoluminescence characterization of a semipolar GaInN based LED sample

    Science.gov (United States)

    Hocker, Matthias; Maier, Pascal; Tischer, Ingo; Meisch, Tobias; Caliebe, Marian; Scholz, Ferdinand; Mundszinger, Manuel; Kaiser, Ute; Thonke, Klaus

    2017-02-01

    A semipolar GaInN based light-emitting diode (LED) sample is investigated by three-dimensionally resolved cathodoluminescence (CL) mapping. Similar to conventional depth-resolved CL spectroscopy (DRCLS), the spatial resolution perpendicular to the sample surface is obtained by calibration of the CL data with Monte-Carlo-simulations (MCSs) of the primary electron beam scattering. In addition to conventional MCSs, we take into account semiconductor-specific processes like exciton diffusion and the influence of the band gap energy. With this method, the structure of the LED sample under investigation can be analyzed without additional sample preparation, like cleaving of cross sections. The measurement yields the thickness of the p-type GaN layer, the vertical position of the quantum wells, and a defect analysis of the underlying n-type GaN, including the determination of the free charge carrier density. The layer arrangement reconstructed from the DRCLS data is in good agreement with the nominal parameters defined by the growth conditions.

  11. Surface charging of phosphors and its effects on cathodoluminescence at low electron energies

    Energy Technology Data Exchange (ETDEWEB)

    Seager, C.H.; Warren, W.L.; Tallant, D.R.

    1997-05-01

    Measurements of the threshold for secondary electron emission and shifts of the carbon Auger line position have been used to deduce the surface potential of several common phosphors during irradiation by electrons in the 0.5--5.0 keV range. All of the insulating phosphors display similar behavior: the surface potential is within {+-}1 V of zero at low electron energies. However, above 2--3 kV it becomes increasingly negative, reaching hundreds of volts within 1 keV of the turn-on energy. The electron energy at which this charging begins decreases dramatically after Coulomb aging at 17 {micro}A/cm{sup 2} for 30--60 min. Measurements using coincident electron beams at low and high electron energies to control the surface potential were made to investigate the dependence of the cathodoluminescence (CL) process on charging. Initially, the CL from the two beams is identical to the sum of the separate beam responses, but after Coulomb aging large deviations from this additivity are observed. These results indicate that charging has important, detrimental effects on CL efficiency after prolonged e-beam irradiation. Measurements of the electron energy dependence of the CL efficiency before and after Coulomb aging will also be presented, and the implications of these data on the physics of the low-voltage CL process will be discussed.

  12. Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

    Science.gov (United States)

    Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

    2016-02-01

    Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

  13. Simultaneous cathodoluminescence and electron microscopy cytometry of cellular vesicles labeled with fluorescent nanodiamonds.

    Science.gov (United States)

    Nagarajan, Sounderya; Pioche-Durieu, Catherine; Tizei, Luiz H G; Fang, Chia-Yi; Bertrand, Jean-Rémi; Le Cam, Eric; Chang, Huan-Cheng; Treussart, François; Kociak, Mathieu

    2016-06-02

    Light and Transmission Electron Microscopies (LM and TEM) hold potential in bioimaging owing to the advantages of fast imaging of multiple cells with LM and ultrastructure resolution offered by TEM. Integrated or correlated LM and TEM are the current approaches to combine the advantages of both techniques. Here we propose an alternative in which the electron beam of a scanning TEM (STEM) is used to excite concomitantly the luminescence of nanoparticle labels (a process known as cathodoluminescence, CL), and image the cell ultrastructure. This CL-STEM imaging allows obtaining luminescence spectra and imaging ultrastructure simultaneously. We present a proof of principle experiment, showing the potential of this technique in image cytometry of cell vesicular components. To label the vesicles we used fluorescent diamond nanocrystals (nanodiamonds, NDs) of size ≈150 nm coated with different cationic polymers, known to trigger different internalization pathways. Each polymer was associated with a type of ND with a different emission spectrum. With CL-STEM, for each individual vesicle, we were able to measure (i) their size with nanometric resolution, (ii) their content in different ND labels, and realize intracellular component cytometry. In contrast to the recently reported organelle flow cytometry technique that requires cell sonication, CL-STEM-based image cytometry preserves the cell integrity and provides a much higher resolution in size. Although this novel approach is still limited by a low throughput, the automatization of data acquisition and image analysis, combined with improved intracellular targeting, should facilitate applications in cell biology at the subcellular level.

  14. Photomosaics of the cathodoluminescence of 60 sections of meteorites and lunar samples

    Science.gov (United States)

    Akridge, D.G.; Akridge, J.M.C.; Batchelor, J.D.; Benoit, P.H.; Brewer, J.; DeHart, J.M.; Keck, B.D.; Jie, L.; Meier, A.; Penrose, M.; Schneider, D.M.; Sears, D.W.G.; Symes, S.J.K.; Yanhong, Z.

    2004-01-01

    Cathodoluminescence (CL) petrography provides a means of observing petrographic and compositional properties of geological samples not readily observable by other techniques. We report the low-magnification CL images of 60 sections of extraterrestrial materials. The images we report include ordinary chondrites (including type 3 ordinary chondrites and gas-rich regolith breccias), enstatite chondrites, CO chondrites and a CM chondrite, eucrites and a howardite, lunar highland regolith breccias, and lunar soils. The CL images show how primitive materials respond to parent body metamorphism, how the metamorphic history of EL chondrites differs from that of EH chondrites, how dark matrix and light clasts of regolith breccias relate to each other, how metamorphism affects eucrites, the texture of lunar regolith breccias and the distribution of crystallized lunar spherules ("lunar chondrules"), and how regolith working affects the mineral properties of lunar soils. More particularly, we argue that such images are a rich source of new information on the nature and history of these materials and that our efforts to date are a small fraction of what can be done. Copyright 2004 by the American Geophysical Union.

  15. New Developments in Cathodoluminescence Spectroscopy for the Study of Luminescent Materials

    Directory of Open Access Journals (Sweden)

    Daniel den Engelsen

    2017-03-01

    Full Text Available Herein, we describe three advanced techniques for cathodoluminescence (CL spectroscopy that have recently been developed in our laboratories. The first is a new method to accurately determine the CL-efficiency of thin layers of phosphor powders. When a wide band phosphor with a band gap (Eg > 5 eV is bombarded with electrons, charging of the phosphor particles will occur, which eventually leads to erroneous results in the determination of the luminous efficacy. To overcome this problem of charging, a comparison method has been developed, which enables accurate measurement of the current density of the electron beam. The study of CL from phosphor specimens in a scanning electron microscope (SEM is the second subject to be treated. A detailed description of a measuring method to determine the overall decay time of single phosphor crystals in a SEM without beam blanking is presented. The third technique is based on the unique combination of microscopy and spectrometry in the transmission electron microscope (TEM of Brunel University London (UK. This combination enables the recording of CL-spectra of nanometre-sized specimens and determining spatial variations in CL emission across individual particles by superimposing the scanning TEM and CL-images.

  16. Pulsed Cathodoluminescence Spectra of Solid Oxides with Low Concentrations of Optically-Active Impurities

    CERN Document Server

    Kozlov, V A; Pestovskii, N V; Petrov, A A; Savinov, S Yu; Zavartsev, Yu D; Zavertyaev, M V; Zagumenniy, A I

    2016-01-01

    Pulsed cathodoluminescence (PCL) spectra of ultra-pure SiO2, GeO2, SnO2, TiO2, La2O3, Y2O3, Sc2O3, CaCO3 powders and {\\alpha}-quartz, Ca:YVO4, LiNbO3 and Sc:LiNbO3 crystals were studied under the same experimental conditions. It was found that PCL spectra of SiO2, SnO2, GeO2, TiO2, La2O3 and CaCO3 powders contain a common band with maximum intensity at 500 nm, PCL spectra of samples Y2O3, Sc2O3, PbWO4 and Ca:YVO4 contain a common band at 490 nm and PCL spectra of LiNbO3 and Sc:LiNbO3 crystals contain a common band at 507 nm. It was found that the average intensity of the PCL spectra and position of the maximum intensity of these common bands depend on the type of a band gap transition of the material. We suppose that these common bands have the same origin in PCL spectra of all the materials studied and are related to recombination of O2--O-oxygen complexes. These complexes appear in the vicinities of anionic and cationic vacancies, where the geometry and orientation of coordination polyhedrons are violated d...

  17. Solid state cathodoluminescence based on tris-(8-hydroxyquinoline) aluminum and its quenching mechanism

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel solid state cathodoluminescence(SSCL) device(the device has a structure of ITO/SiO2/Alq3/SiO2/Al) is fabricated using organic materials as the fluorescent film sandwiched between two SiO2 layers.When alternating current(AC) voltage is applied to this device,uniform emissions are observed.When the voltage is 50 V,a longer wavelength emission(522 nm) is obtained,but the shorter wavelength emission(465 nm) is dominant when the voltage is 76 V.The origins of these emissions are discussed.The interface formed between SiO2 and tris-(8-hydroquinoline) aluminum(Alq3) of SSCL device was investigated by using X-ray photoelectron spectroscopy(XPS).Analyses of the XPS spectra reveal a deep diffusion of the indium into the interface.On the other hand,the interaction between indium and Alq3 occurs at the interface and results in the formation of a carbon-oxygen-metal(In or Al) complex in the contact region.This effect causes a luminescence quenching in the SSCL device.

  18. Cathodoluminescence spectrum imaging analysis of CdTe thin-film bevels

    Science.gov (United States)

    Moseley, John; Al-Jassim, Mowafak M.; Guthrey, Harvey L.; Burst, James M.; Duenow, Joel N.; Ahrenkiel, Richard K.; Metzger, Wyatt K.

    2016-09-01

    We conducted T = 6 K cathodoluminescence (CL) spectrum imaging with a nanoscale electron beam on beveled surfaces of CdTe thin films at the critical stages of standard CdTe solar cell fabrication. We find that the through-thickness CL total intensity profiles are consistent with a reduction in grain-boundary recombination due to the CdCl2 treatment. The color-coded CL maps of the near-band-edge transitions indicate significant variations in the defect recombination activity at the micron and sub-micron scales within grains, from grain to grain, throughout the film depth, and between films with different processing histories. We estimated the grain-interior sulfur-alloying fraction in the interdiffused CdTe/CdS region of the CdCl2-treated films from a sample of 35 grains and found that it is not strongly correlated with CL intensity. A kinetic rate-equation model was used to simulate grain-boundary (GB) and grain-interior CL spectra. Simulations indicate that the large reduction in the exciton band intensity and relatively small decrease in the lower-energy band intensity at CdTe GBs or dislocations can be explained by an enhanced electron-hole non-radiative recombination rate at the deep GB or dislocation defects. Simulations also show that higher GB concentrations of donors and/or acceptors can increase the lower-energy band intensity, while slightly decreasing the exciton band intensity.

  19. Cathodoluminescence spectrum imaging analysis of CdTe thin-film bevels

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA; Al-Jassim, Mowafak M. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Guthrey, Harvey L. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Burst, James M. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Duenow, Joel N. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Ahrenkiel, Richard K. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA; Metzger, Wyatt K. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA

    2016-09-09

    We conducted T = 6 K cathodoluminescence (CL) spectrum imaging with a nanoscale electron beam on beveled surfaces of CdTe thin films at the critical stages of standard CdTe solar cell fabrication. We find that the through-thickness CL total intensity profiles are consistent with a reduction in grain-boundary recombination due to the CdCl2 treatment. The color-coded CL maps of the near-band-edge transitions indicate significant variations in the defect recombination activity at the micron and sub-micron scales within grains, from grain to grain, throughout the film depth, and between films with different processing histories. We estimated the grain-interior sulfur-alloying fraction in the interdiffused CdTe/CdS region of the CdCl2-treated films from a sample of 35 grains and found that it is not strongly correlated with CL intensity. A kinetic rate-equation model was used to simulate grain-boundary (GB) and grain-interior CL spectra. Simulations indicate that the large reduction in the exciton band intensity and relatively small decrease in the lower-energy band intensity at CdTe GBs or dislocations can be explained by an enhanced electron-hole non-radiative recombination rate at the deep GB or dislocation defects. Simulations also show that higher GB concentrations of donors and/or acceptors can increase the lower-energy band intensity, while slightly decreasing the exciton band intensity.

  20. Biosynthesis of cathodoluminescent zinc oxide replicas using butterfly (Papilio paris) wing scales as templates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Wang [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 200240, Shanghai (China); Zhang Di [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 200240, Shanghai (China)], E-mail: zhangdi@sjtu.edu.cn; Fan Tongxiang; Ding Jian; Gu Jiajun [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 200240, Shanghai (China); Guo Qixin; Ogawa, Hiroshi [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan)

    2009-01-01

    Papilio paris butterflies have an iridescent blue color patch on their hind wings which is visible over a wide viewing angle. Optical and scanning electron microscopy observations of scales from the wings show that the blue color scales have very different microstructure to the matt black ones which also populate the wings. Scanning electron micrographs of the blue scales show that their surfaces comprise a regular two-dimensional array of concavities. By contrast the matt black scales have fine, sponge-like structure, between the ridges and the cross ribs in the scales. Using both types of scale as bio-templates, we obtain zinc oxide (ZnO) replicas of the microstructures of the original scales. Room temperature (T = 300 K) cathodoluminescence spectra of these ZnO replicas have also been studied. Both spectra show a similar sharp near-band-edge emission, but have different green emission, which we associate with the different microstructures of the ZnO replicas.

  1. Photo and cathodoluminescence characteristics of dysprosium doped yttrium oxide nanoparticles prepared by Polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Balderas-Xicohténcatl, R., E-mail: rbalderas@fis.cinvestav.mx [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07360, México, D.F. (Mexico); Martínez-Martínez, R. [Instituto de Física y Matemáticas, Universidad Tecnológica de la Mixteca, Carretera a Acatlima Km. 2.5, Huajuapan de León, Oaxaca 69000 (Mexico); Rivera-Alvarez, Z.; Santoyo-Salazar, J.; Falcony, C. [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07360, México, D.F. (Mexico)

    2014-02-15

    The luminescent characteristics of Dy{sup 3+}-doped Y{sub 2}O{sub 3} nanopowders synthesized using the polyol method are reported. The Y{sub 2}O{sub 3} nanoparticles presented a cubic phase crystalline structure of Y{sub 2}O{sub 3} after an annealing treatment in oxygen ambient at temperatures above 600 °C. The averaged crystallite size determined from the X-ray diffraction peaks width was in the 20–32 nm range depending on the annealing temperature. Scanning and transmission electron microscopy studies indicate the formation of nanoparticle aggregates up to 175 nm in diameter. Photoluminescence and cathodoluminescence measurements show a predominant emission at 573 nm, which is attributed to the {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} of the Dy{sup 3+} ion. The luminescence emission dependence with the dopant concentration and post-annealing temperatures is discussed. -- Highlights: • Nanoparticles of Y{sub 2}O{sub 3}:Dy{sup 3+} have been successfully synthesized by the polyol method. • XRD shows a grain size from 20 to 32 nm which is in agreement with SEM and TEM. • Electronic micrographs indicate the formation agglomerates of ∼175 nm. • The method used in the synthesis is industrial scalable and a low cost. • CL emission is observed at naked eye.

  2. Simultaneous cathodoluminescence and electron microscopy cytometry of cellular vesicles labeled with fluorescent nanodiamonds

    Science.gov (United States)

    Nagarajan, Sounderya; Pioche-Durieu, Catherine; Tizei, Luiz H. G.; Fang, Chia-Yi; Bertrand, Jean-Rémi; Le Cam, Eric; Chang, Huan-Cheng; Treussart, François; Kociak, Mathieu

    2016-06-01

    Light and Transmission Electron Microscopies (LM and TEM) hold potential in bioimaging owing to the advantages of fast imaging of multiple cells with LM and ultrastructure resolution offered by TEM. Integrated or correlated LM and TEM are the current approaches to combine the advantages of both techniques. Here we propose an alternative in which the electron beam of a scanning TEM (STEM) is used to excite concomitantly the luminescence of nanoparticle labels (a process known as cathodoluminescence, CL), and image the cell ultrastructure. This CL-STEM imaging allows obtaining luminescence spectra and imaging ultrastructure simultaneously. We present a proof of principle experiment, showing the potential of this technique in image cytometry of cell vesicular components. To label the vesicles we used fluorescent diamond nanocrystals (nanodiamonds, NDs) of size ~150 nm coated with different cationic polymers, known to trigger different internalization pathways. Each polymer was associated with a type of ND with a different emission spectrum. With CL-STEM, for each individual vesicle, we were able to measure (i) their size with nanometric resolution, (ii) their content in different ND labels, and realize intracellular component cytometry. In contrast to the recently reported organelle flow cytometry technique that requires cell sonication, CL-STEM-based image cytometry preserves the cell integrity and provides a much higher resolution in size. Although this novel approach is still limited by a low throughput, the automatization of data acquisition and image analysis, combined with improved intracellular targeting, should facilitate applications in cell biology at the subcellular level.Light and Transmission Electron Microscopies (LM and TEM) hold potential in bioimaging owing to the advantages of fast imaging of multiple cells with LM and ultrastructure resolution offered by TEM. Integrated or correlated LM and TEM are the current approaches to combine the advantages of

  3. Distinguishing the Asian dust sources based on cathodoluminescence analysis of single quartz grain

    Science.gov (United States)

    Nagashima, K.; Nishido, H.; Kayama, M.; Tada, R.; Isozaki, Y.; Sun, Y.; Igarashi, Y.

    2009-12-01

    Numerous tracers, such as mineralogical component, strontium (87Sr/86Sr) and neodymium (eNd(0)) isotopes (Liu et al., 1994; Biscaye et al.,1997; Bory et al., 2002, 2003; Kanayama et al., 2002, 2005), rare earth element composition (e.g., Svensson et al., 2000), oxygen isotope (Mizota et al., 1992; Hou et al., 2003) and ESR intensity of quartz (Ono et al., 1998; Sun et al., 2007), have been investigated to discriminate source areas of Asian dust. However, these analyses need large volume of samples (mostly more than 10 mg) and the applications to the dust samples are limited. Then, here we developed a provenance-tracing method by using a cathodoluminescence (CL) spectral of “single” quartz grain for applying it to small volume of aeolian dust samples, such as aeolian dust in the ice cores and marine sediments with the location of long distance from the Asian deserts. CL is the emission from a material which is excited by electron beam. Since CL spectroscopy and microscopy provide information on the existence and distribution of defects and trace elements in minerals, CL analyses have potential to characterize dust-source areas. CL spectra of quartz have been demonstrated to show different patterns between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins (e.g., Zinkernagel, 1978; Götze et al., 2001), suggesting the spectra reflect the condition of the quartz formation and the local environment. Then, here we conducted CL spectral analysis of silt size quartz in the surface samples from the major Asian deserts, such as the Taklimakan Desert and Gobi Desert in southern Mongolia (hereafter Mongolian Gobi). CL spectra were measured in the areas of approximately 4 micron square for each quartz grain by a Scanning Electron Microscope-Cathodoluminescence (SEM-CL) at the Okayama University of Science, a SEM (Jeol: JSM-5410) attached with a grating monochromator (Oxford Instruments: Mono CL2), where EDS system can be used in combination with SEM

  4. Correlative cathodoluminescence and near-infrared fluorescence imaging for bridging from nanometer to millimeter scale bioimaging.

    Science.gov (United States)

    Niioka, H; Fukushima, S; Ichimiya, M; Ashida, M; Miyake, J; Araki, T; Hashimoto, M

    2014-11-01

    Correlative light and electron microscopy (CLEM) is one attractive method of observing biological specimens because it combines the advantages of both light microscopy (LM) and electron microscopy (EM). In LM, specimens are fully hydrated, and molecular species are distinguished based on the fluorescence colors of probes. EM provides both high-spatial-resolution images superior to those obtained with LM and ultrastructural information of cellular components. The combination of LM and EM gives much more information than either method alone, which helps us to analyze cellular function in more detail.We propose a Y2O3:Tm,Yb phosphor nanoparticle which allows upconversion luminescence (UCL) imaging with near-infrared (NIR) light excitation and cathodoluminescence (CL) imaging [1], where the light emission induced by an electron beam is called cathodoluminescence (CL). Due to electron beam excitation, the spatial resolution of CL microscopy is on the order of nanometers [2,3]. Upconversion is a process in which lower energy, longer wavelength excitation light is transduced to higher energy, shorter wavelength emission light. So far, in LM observation for CLEM, ultraviolet (UV) or visible light has been used for excitation. However, UV and visible light have limited ability to observe deep tissue regions due to absorption, scattering, and autofluorescence. On the other hand, NIR light does not suffer from these problems. Rare-earth-doped upconversion nanophosphors have been applied to biological imaging because of the advantages of NIR excitation [4].We investigated the UCL and CL spectra of Y2O3:Tm,Yb nanophosphors. Y2O3:Tm,Yb nanophosphors that emit visible and near-infrared UCL under 980nm irradiation and blue CL via electron beam excitation. To confirm bimodality of our nanophosphors, correlative UCL/CL images of the nanophosphors were obtained for the same region. The nanophosphors were poured onto a P doped Si substrate (Fig. 1(a)) and were irradiated with 980 nm

  5. Cathodoluminescence emission of REE (Dy, Pr and Eu) doped LaAlO3 phosphors

    Science.gov (United States)

    Boronat, C.; Rivera, T.; Garcia-Guinea, J.; Correcher, V.

    2017-01-01

    Luminescence emission from rare earth (REE) ions doped materials are being of interest since can be employed as scintillators, catalysts, battery and magnetic materials, etc. We herein report on the preliminary results obtained from the cathodoluminescence (CL) properties of undoped LaAlO3 (LAO) and LaAlO3: REE3+ (REE=Dy3+, Pr3+ and Eu3+) samples synthesized by a sol-gel process based on the Pechini's method with a spray-drying technique. The samples, previously characterized by means of Environmental Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis Spectrometry, display CL spectra with well-defined peaks that could specifically be associated with the LAO structure (in the range of 300-450 nm) and point defects (from 450 to 800 nm) spectral regions. The observed wavebands are as follows: (i) 480 and 570 from the Dy-doped LAO correspond respectively to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, (ii) 490-638 from the Pr-doped LAO is linked to 3P0→3H4, 1D2→3H4 transitions and (iii) 590 and 620 where the dopant Eu3+ gives rise to 5D0→7F1 and 5D0→7F2 transitions and (iv) a UV-blue broad band is associated with NBHOC in undoped LAO. Such emissions are due to the presence of the 4f electrons of rare earth ions that are shielded by the outer 5s and 5p electrons, the intra-4f emission spectra of REE that induce sharp and narrow wavebands.

  6. Diagenetic history of lower Pliocene rhodoliths of the Azores Archipelago (NE Atlantic): Application of cathodoluminescence techniques.

    Science.gov (United States)

    Rebelo, A C; Meireles, R P; Barbin, V; Neto, A I; Melo, C; Ávila, S P

    2016-01-01

    The diagenetic history of calcareous fossils is required for their application as palaeoenvironmental indicators. In this study, cathodoluminescence-microscopy (CL microscopy) and back scatter electron image-energy dispersive X-ray spectroscopy (BSE-EDS microscopy) were applied to Pliocene rhodoliths from the Azores Archipelago (NE Atlantic) in order to gain additional insight regarding the trace element content distribution throughout the algae thalli, and to ascertain palaeoenvironmental interpretations. Two types of luminescence were obtained: (1) high and (2) low luminescence. Rhodoliths with high luminescence are related with high concentrations of Mn(2+) in seawater and low luminescence rhodoliths are related with low concentrations of Mn(2+) in seawater. When the rhodoliths were deposited at about 4.0-4.5 Ma, the shoreline configuration of Santa Maria Island was much different than today. The influence of volcanic activity due to the extrusion of lavas and associated products and/or the presence of active shallow-water hydrothermal vents, was reflected in the sea water chemistry, with penecontemporaneous palaeoshores of the island featuring a high sea water concentration of Mn(2+), which mirrored on the rhodolith Mn(2+) high concentration. By contrast, rhodoliths located about 2.8 and 2.9 km from the shore, in areas with low seawater Mn(2+) concentration, had low luminescence, reflecting the low Mn(2+) concentration in seawater. Rhodoliths chemical data and the geological history of the island proved to be congruent with the palaeogeographical reconstruction of Santa Maria Island at the time of the formation of the rhodoliths.

  7. Cathodoluminescence and green-thermoluminescence response of CaSO{sub 4}:Dy,P films

    Energy Technology Data Exchange (ETDEWEB)

    Roman-Lopez, J., E-mail: holand_jeos@hotmail.com [CICATA-IPN, Legaria 694, D.F. 11500, Mexico, CIEMAT, Av., Complutense 22, Madrid 28040 (Spain); Correcher, V. [CIEMAT, Av., Complutense 22, Madrid 28040 (Spain); Garcia-Guinea, J. [Museo Nacional de Ciencias Naturales (CSIC), Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Rivera, T.; Lozano, I.B. [CICATA-IPN, Legaria 694, D.F. 11500 (Mexico)

    2013-03-15

    We herein report on the cathodoluminescence (CL) and green-thermoluminescence (TL) emission of CaSO{sub 4}:Dy,P films deposited by the spray pyrolysis method at different temperatures. The samples have been previously structurally and chemically characterized by means of Raman spectroscopy and energy dispersive spectroscopy (EDS). The CL spectra show (i) a broad emission band centered at 374 nm that corresponds to the intrinsic emission of (SO{sub 4}){sup 2-} and (ii) emission bands centered on 486, 574, 668, 758 nm assigned to the electronic transitions of the Dy{sup 3+} ions. The TL glow curves of the films showed three groups of components peaked at around of 98, 152 and 300 Degree-Sign C that exhibit a gradual and progressively linear shifting of the T{sub max} as function of T{sub stop}. This TL behavior is related to a continuum in the trap distribution associated with general or multi-order kinetics and involving continuous processes of trapping-detrapping. The activation energy in the range of 0.97-1.53 eV has been estimated using the initial rise method. - Highlights: Black-Right-Pointing-Pointer The CaSO{sup 4}:Dy,P films were prepared by using the ultrasonic spray pyrolysis method. Black-Right-Pointing-Pointer Luminescence spectra of the CaSO{sub 4}:Dy,P films display the emission bands of the ions (SO{sub 4}){sup 2-} and Dy{sup 3+}. Black-Right-Pointing-Pointer The CaSO{sub 4}:Dy,P films were irradiated with a {sup 90}Sr/{sup 90}Y beta source. Black-Right-Pointing-Pointer The TL intensity of the films depends on the temperature of deposit.

  8. Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities

    Energy Technology Data Exchange (ETDEWEB)

    Bondar, V D; Felter, T E; Hunt, C E; Dubov, Y G; Chakhovskoi, A G

    2001-05-06

    Long-term processes of cathodoluminescence degradation of thin film phosphors Zn{sub 2}SiO{sub 4}:Ti and Zn{sub 2}GeO{sub 4}:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing decreasing of emission intensity have been found. At high-level densities of e-beam irradiation the specific behavior of long-term degradation processes was observed, which is characteristic with rapid degradation at initial stage and slow consequent decrease of intensity. The most probable mechanisms responsible for long-term processes of degradation in investigated phosphors are proposed.

  9. Long-Term Cathodoluminescent Characterization of Thin-Film Oxide Phosphors in a Wide Range of Electron Excitation Densities

    Energy Technology Data Exchange (ETDEWEB)

    Bondar, V D; Felter, T E; Hunt, C E; Dubov, Y G; Chakhovskoy, A G

    2001-04-09

    Long-term processes of cathodoluminescence degradation of thin film phosphors Zn{sub 2}SiO{sub 4}:Ti and Zn{sub 2}GeO{sub 4}:Mn were investigated in a wide range of e-beam energies, current and power densities. The time dependencies describing decreasing of emission intensity have been found. At high-level densities of e-beam irradiation the specific behavior of long-term degradation processes was observed, which is characteristic with rapid degradation at initial stage and slow consequent decrease of intensity. The most probable mechanisms responsible for long-term processes of degradation in investigated phosphors are proposed.

  10. Fluid inclusion and cathodoluminescence studies on fluorite from the Kerio valley, Kenya

    Science.gov (United States)

    Ogola, J. S.; Behr, H. J.; van den Kerkhof, A. M.

    1994-04-01

    The Kerio valley lies between the Elgeyo escarpment and the Tugen hills which mark the western margin of the Kenya rift valley. The main fluorite deposits are located in the southern part of the valley at Kimwarer, Choff and Kamnaon. Three types of inclusion fillings were identified: Liquid+Vapour, Liquid+Daughter Minerals and Liquid. The L+V type is dominant. Inclusions occur as clusters, trails along the crystal growth zones and as isolated ones. Low salinities, apparently lower than the 5% wt. NaCl equivalent, were established. Homogenization temperatures suggest that fluorite mineralization took place at different stages and at temperatures between 120 and 180 °C. Isolated readings above 180°C may be referring to the original inclusions in limestone. These measurements and the absence of CO 2 in the inclusions, as well as the occurrence of vugs and crustifications with fluorite, suggest that mineralization took place at relatively shallow depths. Emission spectrum lines representing Eu 2+, Dy 3+, Tb 3+ and Sm 3+ in fluorite were identified. Sm 3+ was detected only in the pinkish luminescence of veined fluorite, whereas the pinkish zone in banded fluorite contains Tb 3+. Eu 2+ which gives the strongest emission lines in the blue part of the visible spectrum, apparently is responsible for the strong blue cathodoluminescence (CL) in fluorite. The dominance of Eu 2+ peaks further points to the fact that fluorite mineralization in the Kerio valley took place in an environment that was enriched in Lanthanide Rare Earth Elements (LREE). The presence of rare earths and radioactive elements in fluorite points towards their enrichment in the environment of fluorite mineralization. A juvenile origin of mineral forming solutions is proposed. Two generations of fluorite were established: allotriomorphic fluorite, forming the matrix, and the idiomorphic variety, occurring either in barite or in druzes in early fluorite. Barite in turn forms idiomorphic crystals in

  11. Trace element composition and cathodoluminescence of kyanite and its petrogenetic implications

    Science.gov (United States)

    Müller, Axel; van den Kerkhof, Alfons M.; Selbekk, Rune S.; Broekmans, Maarten A. T. M.

    2016-09-01

    Kyanite crystals from fourteen localities worldwide were analysed for their abundances of the trace elements Na, Mg, K, Ca, Ti, V, Cr, Mn, and Fe and cathodoluminescence (CL) properties. Based on protolith type, metamorphic setting, and distinctive trace element fingerprints, a genetic classification of kyanite-bearing rocks is suggested: (A) Al-rich metasediments which commonly contain coarse-grained quartz-kyanite segregations; (B) metamorphosed granitic rocks, specifically granulites; (C) metamorphosed argillic alteration zones hosted originally in felsic igneous rocks; (D) metamorphosed argillic alteration zones hosted originally in mafic igneous rocks; and (E) metamorphosed mafic to ultramafic rocks, specifically eclogites. Vanadium and Cr concentrations reflect both protolith and host rock compositions and therefore may provide a geochemical fingerprint for the nature of the protolith. The incorporation of Fe into kyanite is largely controlled by oxygen fugacity during kyanite formation, and therefore, in most cases, its concentration cannot be related to that of the protolith. From our results, Ti concentration appears to be related to metamorphic grade, particularly formation temperature. If proven by further studies, Ti-in-kyanite may provide a useful geothermometer. Correlation of trace element abundances with CL spectra confirms that common red CL, which is composed of the spectral bands centred at 1.69 eV (734 nm), 1.75 eV (708 nm), and 1.80 eV (689 nm), is related to Cr3+ defects. CL spectra of most kyanites show in addition a low-intensity blue emission centred at 2.56 eV (485 nm). Correlation of the intensity of the blue emission with Ti suggests that it is related to or sensitized by Ti4+ or Ti3+ defects. Kyanites with >3200 µgg-1 Fe show generally no detectable CL due to the CL-quenching effect of Fe2+. Our findings provide new criteria in the exploration for and quality assessment of new kyanite deposits. The Ti content, one of the critical

  12. Comparison of thermoluminescence (TL) and cathodoluminescence (ESEM-CL) properties between hydrothermal and metamorphic quartzes

    Energy Technology Data Exchange (ETDEWEB)

    Topaksu, M., E-mail: mtopaksu@adiyaman.edu.tr [Department of Physics, Faculty of Science and Art, Adiyaman University, 02040 Adiyaman (Turkey); Correcher, V. [CIEMAT, Av. Complutense 22, Madrid 28040 (Spain); Garcia-Guinea, J. [CSIC, Museo Nacional de Ciencias Naturales, C/Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Topak, Y. [Adiyaman University, Vocational High School, 02040 Adiyaman (Turkey); Goeksu, H.Y. [Department of Physics, Faculty of Science and Art, Adiyaman University, 02040 Adiyaman (Turkey)

    2012-06-15

    This paper reports on the Thermoluminescence (TL) and Cathodoluminescence (CL) emission of well-characterized hydrothermal milky quartz specimens from Hakkari in Turkey, labeled THQ, and Madrid in Spain, labeled SHQ, and metamorphic quartz from Madrid, in Spain, labeled SMQ. Both hydrothermal and metamorphic quartz samples display similar UV-IR CL spectra consisting of five groups of components centered at 330 nm and 380 nm linked to [AlO{sub 4}] Degree-Sign centers, 420 nm due to intrinsic defects such as oxygen vacancies, lattice defects, and impurities which modify the crystal structure, 480 nm associated with [AlO{sub 4}] Degree-Sign centers of substitutional Al{sup 3+}, and a red broad band related to the hydroxyl defects in the quartz lattice as precursors of non-bridging oxygen hole centers (NBOHC) and substitutional point defects. The Turkish quartz specimen exhibits higher CL intensity in the UV region (up to 330 nm) than the Spanish specimens probably linked to the presence of Ca (0.95% in THQ and less than 0.1% in SHQ and SMQ). At wavelengths greater than 330 nm, SMQ (formed at high pressure 6000 bars and temperatures over 500-600 Degree-Sign C) shows higher intensity than the hydrothermal (growth at 2000 bars and temperatures 200-300 Degree-Sign C) samples associated with the formation process. The natural blue TL glow curves of both THQ and SHQ display a weaker TL intensity than the SMQ, attributable to the Al (0.32%), Ti (0.14%), K (0.01%) and Zr (76 ppm) content. It is shown that mineralogical formation, crystallinity index and the content of the impurities seem to be the main parameters of influence in the shape intensity of the CL and TL glow curve emission. - Highlights: Black-Right-Pointing-Pointer We reported on the TL and CL emission of well-characterized hydrothermal milky and metamorphic quartz specimens. Black-Right-Pointing-Pointer Hydrothermal and metamorphic quartz samples displayed similar UV-IR CL spectra. Black

  13. Distinction between amorphous and healed planar deformation features in shocked quartz using composite color scanning electron microscope cathodoluminescence (SEM-CL) imaging

    NARCIS (Netherlands)

    Hamers, Maartje F.; Pennock, Gill M.; Herwegh, Marco; Drury, Martyn R.

    2016-01-01

    Planar deformation features (PDFs) in quartz are one of the most reliable and most widely used forms of evidence for hypervelocity impact. PDFs can be identified in scanning electron microscope cathodoluminescence (SEM-CL) images, but not all PDFs show the same CL behavior: there are nonluminescent

  14. UHP-Metamorphic Pyrope Quartzites From Dora Maira: Cathodoluminescence of Silica and Twinning of Coesite

    Science.gov (United States)

    Schertl, H.; Medenbach, O.; Neuser, R. D.

    2005-12-01

    Since the first discovery of metamorphic coesite in ultrahigh-pressure (UHP) rocks from the Dora Maira Massif/Western Alps, much attention was drawn on its characteristics: the paragenesis, influence of OH on the kinetics of the coesite-quartz transition, present day overpressure in coesite inclusions, features like palisade-quartz as typical breakdown product, experimental studies on the rheology of polycrystalline coesite, oxygen isotope signatures, etc. Here we would like to focus on the cathodoluminescence (CL) of coesite and its breakdown products. Since luminescence is triggered even by minor differences in composition or structure of a mineral, in this study the CL microscope is employed not only as a powerful tool to distinguish between different mineral phases but also to characterize different generations of a coesite breakdown product. A second topic concerns the twinning of coesite which is very rarely observed in nature. The investigations were made on pyrope quartzite previously representing a pyrope coesitite at UHP metamorphic conditions (Chopin, 1984; Schertl et al., 1991). Main constituent phases are pyrope, quartz, phengite, talc, and kyanite with minor amounts of coesite and jadeite. The rock can be subdivided in a fine-grained type containing pyropes up to about 1.5 cm and a coarse-grained type with pyrope crystals up to 25 cm. The boundaries between both types are irregular, but they exhibit significant differences concerning their mineral inclusions: inclusions of coesite/quartz (in paragenesis with kyanite and phengite) are only observed in small pyropes whereas in big pyropes no silica phase occurs. Typical mineral inclusions in big pyropes essentially are kyanite, talc, and chlorite with minor amounts of ellenbergerite, Mg-dumortierite and sodic amphibole. Coesite typically shows bluish-green luminescence colours, whereas palisade-like quartz as breakdown product (interpreted to be formed at high temperatures) surrounding coesite is

  15. Surface Characterisation and Cathodoluminescent Response of Nanodot-Patterned GaSb Surfaces by Low Energy Ion Sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, J L [Laboratorio de Crecimiento de Cristales, Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049, Cantoblanco, Madrid (Spain); Hidalgo, P [Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, 28045, Madrid (Spain); Dieguez, E [Laboratorio de Crecimiento de Cristales, Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049, Cantoblanco, Madrid (Spain)

    2007-04-15

    The scope of this paper is to analyse the effect of Au and Cr impurities, diffused onto GaSb substrates on the formation of nanodots created by LEIS using Ar+ ions It is concluded that oblique incidence in rotating configuration delays the formation of the nanodots compared to previously reported normal incidence experiments. The presence of cracks induced by the sputtering process has been observed both in the Au and Cr diffused samples. Cathodoluminescence (CL) spectra obtained in irradiated samples both pure and Crdiffused have revealed no difference between them, showing the usual three band encountered in this material (Band Gap at 798 meV, A Band at 777 meV and tail-states at 815 meV). However, a fourth band has been detected in the Au sample centered at 769 meV.

  16. Cathodoluminescence and electroluminescence from multi-layered organic structures induced by field electron emission from carbon nanotubes

    Science.gov (United States)

    Kuznetzov, Alexander A.; Zakhidov, Alexander A.; Ovalle, Raquel; Nanjundaswami, Rashmi; Williams, Christopher; Zhang, Mei; Lee, Sergey B.; Ferraris, John; Zakhidov, Anvar A.

    2005-10-01

    We report the observation of cathodoluminescence (CL) of organic multilayers of tris-(8-hydroxyquinoline) aluminium (Alq3) and 2- (4biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) deposited on ITO-coated glass, with and without hole transport layer and compare it with electroluminescence (EL) from similar devices. Excitation of the CL of such multilayer organic anodes was accomplished by low energy electrons field emitted by single walled carbon nanotube cathodes. The dependence of CL spectrum and intensity on voltage (V), current (I), type of transport layer and the cathode-anode geometry has been studied. We propose carbon nanotubes as efficient cathodes for stable CL emission from multi-layer anodes at small cathode-anode separations. The role of hole-transport layer is also discussed.

  17. Cathodoluminescence, laser ablasion inductively coupled plasma mass spectrometry, electron probe microanalysis and electron paramagnetic resonance analyses of natural sphalerite

    Science.gov (United States)

    Karakus, M.; Hagni, R.D.; Koenig, A.; Ciftc, E.

    2008-01-01

    Natural sphalerite associated with copper, silver, lead-zinc, tin and tungsten deposits from various world-famous mineral deposits have been studied by cathodoluminescence (CL), laser ablasion inductively coupled plasma mass spectrometry (LA-ICP-MS), electron probe microanalysis (EPMA) and electron paramagnetic resonance (EPR) to determine the relationship between trace element type and content and the CL properties of sphalerite. In general, sphalerite produces a spectrum of CL colour under electron bombardment that includes deep blue, turquoise, lime green, yellow-orange, orange-red and dull dark red depending on the type and concentration of trace quantities of activator ions. Sphalerite from most deposits shows a bright yellow-orange CL colour with ??max centred at 585 nm due to Mn2+ ion, and the intensity of CL is strongly dependent primarily on Fe2+ concentration. The blue emission band with ??max centred at 470-490 nm correlates with Ga and Ag at the Tsumeb, Horn Silver, Balmat and Kankoy mines. Colloform sphalerite from older well-known European lead-zinc deposits and late Cretaceous Kuroko-type VMS deposits of Turkey shows intense yellowish CL colour and their CL spectra are characterised by extremely broad emission bands ranging from 450 to 750 nm. These samples are characterised by low Mn (behaviour of sphalerite serves to characterise ore types and help detect technologically important trace elements.

  18. Trace elements and cathodoluminescence of detrital quartz in Arctic marine sediments – a new ice-rafted debris provenance proxy

    Directory of Open Access Journals (Sweden)

    A. Müller

    2013-07-01

    Full Text Available The records of ice-rafted debris (IRD provenance in the North Atlantic – Barents Sea allow the reconstruction of the spatial and temporal changes of ice-flow drainage patterns during glacial and deglacial periods. In this study a new approach to characterisation of the provenance of detrital quartz grains in the fraction > 500 μm of marine sediments offshore of Spitsbergen is introduced, utilizing scanning electron microscope backscattered electron and cathodoluminescence (CL imaging, combined with laser ablation inductively-coupled plasma mass spectrometry. Based on their micro-inclusions, CL and trace element characteristics the investigated IRD grains can be classified into five distinct populations. Three of the populations are indicative of potential IRD provenance provinces in the Storfjord area including Barentsøya and Egdeøya. The results imply that under modern (interglacial conditions IRD deposition along the western Spitsbergen margin is mainly governed by the East Svalbard Current controlling the ice-drift pattern. The presence of detrital quartz from local provinces, however, indicates that variations in IRD supply from western Spitsbergen may be quantified as well. In this pilot study it is demonstrated that this new approach applied on Arctic continental margin sediments, bears a considerable potential for the definition of the sources of IRD and thus of spatial/temporal changes in ice-flow drainage patterns during glacial/interglacial cycles.

  19. Influences of Interfacial Misfit Dislocations on Cathodoluminescence of ZnS/GaAs(001) Studied by Transmission Electron Microscopy

    Science.gov (United States)

    Mitsui, Tadashi; Yamamoto, Naoki

    2000-03-01

    The change in cathodoluminescence (CL) spectra of thin ZnS films grown by molecular beam epitaxy (MBE) on GaAs(001) has been examined by a low-temperature CL measurement system combined with a transmission electron microscope (TEM). It was found that structural defects such as dislocations and stacking faults formed in the ZnS films seriously affect CL intensity within a distance of 200 nm from the interface, and their effect becomes negligibly small at distances of more than 600 nm. The relative intensities of the exciton-associated emissions are small in comparison with the non-exciton-associated emissions for the thin samples that have relatively large stacking fault densities. This fact suggests that the stacking faults accompanying the partial dislocations suppress the generation of excitons. Moreover, the peak of the non-exciton-associated emission shifts markedly to long wavelengths, as the epitaxial layer thickness becomes less than 200 nm. The peak shift is attributed to the internal stress change in the ZnS film due to the stress caused by the lattice mismatch and the relaxation by the introduced defects.

  20. Cathodoluminescence Phenomena of Treated Rubies%优化处理红宝石的阴极发光特征

    Institute of Scientific and Technical Information of China (English)

    李敬敬

    2012-01-01

    使用阴极发光仪对热处理红宝石、染色处理红宝石、充填处理红宝石样品进行发光现象观察,并与天然红宝石、合成红宝石的阴极发光现象对比,得知优化红宝石的阴极发光现象与天然红宝石相近,而处理红宝石的发光强度比天然红宝石及合成红宝石要弱,但处理特征在阴极发光仪下清晰可见.%In this paper,experiments were made on series of rubies with the help of cathodoluminescence instrument;and luminous phenomena of heat-treated ruby,dyed ruby ,and filling processing ruby samples were discussed. Conclusions are drawn that luminous phenomenon of enhancing rubies is similar to that of natural rubies, yet luminous intensity of treated rubies is poorer than that of natural and synthetic rubies.

  1. A study of cathodoluminescence and trace element compositional zoning in natural quartz from volcanic rocks: mapping titanium content in quartz.

    Science.gov (United States)

    Leeman, William P; MacRae, Colin M; Wilson, Nick C; Torpy, Aaron; Lee, Cin-Ty A; Student, James J; Thomas, Jay B; Vicenzi, Edward P

    2012-12-01

    This article concerns application of cathodoluminescence (CL) spectroscopy to volcanic quartz and its utility in assessing variation in trace quantities of Ti within individual crystals. CL spectroscopy provides useful details of intragrain compositional variability and structure but generally limited quantitative information on element abundances. Microbeam analysis can provide such information but is time-consuming and costly, particularly if large numbers of analyses are required. To maximize advantages of both approaches, natural and synthetic quartz crystals were studied using high-resolution hyperspectral CL imaging (1.2-5.0 eV range) combined with analysis via laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Spectral intensities can be deconvolved into three principal contributions (1.93, 2.19, and 2.72 eV), for which intensity of the latter peak was found to correlate directly with Ti concentration. Quantitative maps of Ti variation can be produced by calibration of the CL spectral data against relatively few analytical points. Such maps provide useful information concerning intragrain zoning or heterogeneity of Ti contents with the sensitivity of LA-ICPMS analysis and spatial resolution of electron microprobe analysis.

  2. Cathodoluminescence spectroscopy of single GaN/AlN quantum dots directly performed in a scanning transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Bertram, Frank; Schmidt, Gordon; Mueller, Marcus; Petzold, Silke; Veit, Peter; Christen, Juergen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Das, Aparna; Monroy, Eva [CEA/CNRS Group Nanophysique et Semiconducteurs, INAC/SP2M, CEA-Grenoble (France)

    2013-07-01

    In this study we will present a nanoscale optical and structural characterization of a III-nitride based quantum dot (QD) heterostructure. A 1 μm thick AlN layer grown on a sapphire substrate using metal organic vapor phase epitaxy (MOVPE) serves as template for the further growth process. Subsequent, a stack of 10 GaN QD layers, each embedded in 50 nm thick AlN barrier, were grown under an optimized plasma-assisted molecular beam epitaxy process on an AlN-MOVPE/sapphire template. The cross-section high angle annular dark field image (HAADF) in a scanning transmission electron microscope (STEM) clearly reveals the GaN QD layers. The comparison of the HAADF image with the simultaneously recorded panchromatic cathodoluminescence mapping at 16 K exhibits a spot like luminescence distribution of the upper six QD layers solely, indicating no formation of the first four intentionally grown QD layers. Addressing a very few to single QDs we observe a broad luminescence between 3.0 eV and 4.0 eV originating from the superposition of the single emission lines.

  3. Cathodoluminescence investigations on quartz cement in the sandstones of Khabour Formation from Iraqi Kurdistan Region, Northern Iraq

    Science.gov (United States)

    Omer, Muhamed F.; Friis, Henrik

    2014-03-01

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic studies showed that the silica cementation occurred in five successive phases which can be distinguished by their luminescence pattern. The precipitations of two phases have predated the major compaction process while the other phases are younger. The successive phases represent a sequence of changes in silica supply which were classified as very early and early, derived from dissolved biogenic silica that precipitated as opal/microquartz, possibly pre-compactional and of non-luminescent quartz overgrowth type. This was followed by phases whose silica supply derived from pressure solution of quartz, dissolution of feldspar, and hydrothermal fluids related to major thrust fault event. These successive quartz cement phases showed an increase in luminescence and the development of complicated zonation pattern in late-stage quartz cementation.

  4. High resolution cathodoluminescence spectroscopy of carbonate cementation in Khurmala Formation (Paleocene-L. Eocene) from Iraqi Kurdistan Region, Northern Iraq

    Science.gov (United States)

    Omer, Muhamed F.; Omer, Dilshad; Zebari, Bahroz Gh.

    2014-12-01

    A combination of high resolution cathodoluminsecnce-spectroscopy (HRS-CL) with spatial electron microprobe analysis and optical microscopy is used to determine paragenesis and history of cementation in the limestones and dolostones of Khurmala Formation which is exposed in many parts of Northern Iraq. Khurmala Formation was subjected to different diagenetic processes such as micritization, compaction, dissolution, neomorphism, pyritization and cementation that occurred during marine to shallow burial stages and culminated during intermediate to deep burial later stages. Five dolomite textures are recognized and classified according to crystal size distribution and crystal-boundary shape. Dolomitization is closely associated with the development of secondary porosity that pre-and postdates dissolution and corrosion; meanwhile such porosity was not noticed in the associated limestones. Microprobe analysis revealed three types of cement, calcite, dolomite and ankerite which range in their luminescence from dull to bright. Cathodoluminescence study indicated four main texture generations. These are (1) unzoned microdolomite of planar and subhedral shape, with syntaxial rim cement of echinoderm that show dull to red luminescence, (2) equant calcite cements filling interparticle pores which shows dull luminescence and weak zonal growth, (3.1) homogenous intrinsic blue stoichiometric calcite with dull luminescence and without activators, (3.2) coarse blocky calcite cement with strong oscillatory zoning and bright orange luminescence which postdates other calcite cements, (4) ankerite cement with red to orange, non-luminescence growth zonation which is the last formed cement.

  5. Carbonate cements and grains in submarine fan sandstones—the Cergowa Beds (Oligocene, Carpathians of Poland) recorded by cathodoluminescence

    Science.gov (United States)

    Pszonka, Joanna; Wendorff, Marek

    2017-01-01

    The cathodoluminescence (CL) observations with cold cathode, supplemented by reconnaissance scanning electron microscope analyses, bring new data on petrology, provenance and diagenesis of the Oligocene-age Cergowa sandstones from the Outer Carpathians (SE Poland). The sandstones represent a variety of mass gravity flow sediments deposited on a submarine fan, which now forms a lenticular lithosome—a part of the Menilite Beds-Krosno Beds suite important for the hydrocarbons industry. The most common components of the Cergowa sandstones observed under the CL are carbonates—cement and grains that are mainly represented by lithoclasts. Carbonate cement is represented by five generations: brown (Cb), orange (Co), yellow (Cy), zoned (Cz) and black (Ck). Pore-filling Cb and Co calcite cements are interpreted as genetically related to eo- and mesodiagenetic phases. The mesodiagenetic phase is characterised by randomly distributed relatively large monocrystalline-zoned rhombs of dolomite cement (Cz) and ankerite/ferroan dolomite (Ck). The telodiagenetic phase is represented by pore-filling yellow calcite (Cy) that crystallised under the influence of suboxic meteoric waters. Lithoclasts represent six microfacies of carbonate rocks eroded in the source area, i.e. microbreccia, tectonised immature calcarenite/wacke, microsparite, sparite, biomicrosparite/packstone and dolostone. Pronounced indentations of terrigenous sand grains into intraclasts of packstone/biomicrosparite, coupled with commonly present similar packstone-type matrix, suggest that a significant part of matrix resulted from compaction of soft biomicrosparite grains. Terrigenous grains bound by calcite cement are commonly corroded by acidic diagenetic fluids, and partial or even complete replacement of silicates by calcite and clay minerals is illustrated here by feldspar grains. Substantial carbonate cementation has resulted in both the significant hardness and abrasion resistance of the Cergowa sandstones

  6. Geochemistry, geochronology, and cathodoluminescence imagery of the Salihli and Turgutlu granites (central Menderes Massif, Western Turkey): Implications for Aegean tectonics

    Science.gov (United States)

    Catlos, E. J.; Baker, C.; Sorensen, S. S.; Çemen, I.; Hançer, M.

    2009-04-01

    The Menderes Massif (western Turkey) is an important metamorphic core complex located in the Aegean region; geochemical and geochronological data from this extensional domain facilitates our understanding of large-scale extension of the Earth's lithosphere. S-type, peraluminous granites (Salihli and Turgutlu) that intrude the Alasehir detachment which bounds the northern edge of the central Menderes Massif may have been generated due to subduction of the Eastern Mediterranean floor along the Hellenic trench. In situ Th-Pb ion microprobe monazite ages from the granites range from 21.7±4.5 Ma to 9.6±1.6 Ma (±1s). The range is consistent with cathodoluminescence (CL) imagery that document complex textures within the samples. Salihli and Turgutlu granites share many similar characteristics, including multiple generations of plagioclase (some with shocked cores consistent with magma mixing), plagioclase replacing K-feldspar and the development of myrmekite, clear evidence for fluid infiltration, and multiple generations of microcracks and microfaults. The granites may have evolved from compositionally distinct magma sources, as Salihli samples in general contain allanite as the major accessory mineral, whereas Turgutlu granites contain monazite. However, the CL imagery document similar alteration textures. Ages reported here are similar to dates constraining extension reported elsewhere in the Aegean, but indicate a level of complexity when linking movement within the Menderes Massif to the large-scale geodynamic processes that created other metamorphic core complexes in the region. Difficulties exist in linking the ages obtained from the granites to specific tectonic events due to the presence of secondary alteration textures, generations of mineral growth, and multiple episodes of deformation.

  7. Three-dimensional cathodoluminescence imaging and electron backscatter diffraction: tools for studying the genetic nature of diamond inclusions

    Science.gov (United States)

    Wiggers de Vries, D. F.; Drury, M. R.; de Winter, D. A. M.; Bulanova, G. P.; Pearson, D. G.; Davies, G. R.

    2011-04-01

    As a step towards resolving the genesis of inclusions in diamonds, a new technique is presented. This technique combines cathodoluminescence (CL) and electron backscatter diffraction (EBSD) using a focused ion beam-scanning electron microscope (FIB-SEM) instrument with the aim of determining, in detail, the three-dimensional diamond zonation adjacent to a diamond inclusion. EBSD reveals that mineral inclusions in a single diamond have similar crystallographic orientations to the host, within ±0.4°. The chromite inclusions record a systematic change in Mg# and Cr# from core to the rim of the diamond that corresponds with a ~80°C decrease of their formation temperature as established by zinc thermometry. A chromite inclusion, positioned adjacent to a boundary between two major diamond growth zones, is multi-faceted with preferred octahedral and cubic faces. The chromite is surrounded by a volume of non-luminescent diamond (CL halo) that partially obscures any diamond growth structures. The CL halo has apparent crystallographic morphology with symmetrically oriented pointed features. The CL halo is enriched in ~200 ppm Cr and ~80 ppm Fe and is interpreted to have a secondary origin as it overprints a major primary diamond growth structure. The diamond zonation adjacent to the chromite is complex and records both syngenetic and protogenetic features based on current inclusion entrapment models. In this specific case, a syngenetic origin is favoured with the complex form of the inclusion and growth layers indicating changes of growth rates at the diamond-chromite interface. Combined EBSD and 3D-CL imaging appears an extremely useful tool in resolving the ongoing discussion about the timing of inclusion growth and the significance of diamond inclusion studies.

  8. Visualizing trace element distribution in quartz using cathodoluminescence, electron microprobe, and laser ablation-inductively coupled plasma-mass spectrometry

    Science.gov (United States)

    Rusk, Brian; Koenig, Alan; Lowers, Heather

    2011-01-01

    Cathodoluminescent (CL) textures in quartz reveal successive histories of the physical and chemical fluctuations that accompany crystal growth. Such CL textures reflect trace element concentration variations that can be mapped by electron microprobe or laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Trace element maps in hydrothermal quartz from four different ore deposit types (Carlin-type Au, epithermal Ag, porphyry-Cu, and MVT Pb-Zn) reveal correlations among trace elements and between trace element concentrations and CL textures. The distributions of trace elements reflect variations in the physical and chemical conditions of quartz precipitation. These maps show that Al is the most abundant trace element in hydrothermal quartz. In crystals grown at temperatures below 300 °C, Al concentrations may vary by up to two orders of magnitude between adjacent growth zones, with no evidence for diffusion. The monovalent cations Li, Na, and K, where detectable, always correlate with Al, with Li being the most abundant of the three. In most samples, Al is more abundant than the combined total of the monovalent cations; however, in the MVT sample, molar Al/Li ratios are ~0.8. Antimony is present in concentrations up to ~120 ppm in epithermal quartz (~200–300 °C), but is not detectable in MVT, Carlin, or porphyry-Cu quartz. Concentrations of Sb do not correlate consistently with those of other trace elements or with CL textures. Titanium is only abundant enough to be mapped in quartz from porphyry-type ore deposits that precipitate at temperatures above ~400 °C. In such quartz, Ti concentration correlates positively with CL intensity, suggesting a causative relationship. In contrast, in quartz from other deposit types, there is no consistent correlation between concentrations of any trace element and CL intensity fluctuations.

  9. Cathodoluminescence characterization of quartz grains from the Upper Cretaceous of dinosaur fossil localities in the Gobi desert, Mongolia

    Science.gov (United States)

    Saneyoshi, M.; Nishido, H.; Masuda, R.; Tsogtbaatar, K.; Chinzorig, T.

    2013-12-01

    The Upper Cretaceous eolian sediments in Mongolia's Gobi desert are one of the most important occurrences of the dinosaurs in the world. Large numbers of confiscated dinosaur fossils illegally worked out by poachers has been stored in the Mongolian Paleontological Center at Ulaanbaatar. In most cases, their localities are unknown. The purpose of this study is to identify their localities by cathodoluminescence (CL) features of quartz grains attached to the dinosaur specimens by comparing to the quartz samples collected from the sediments of circumjacent resources in this area. This study focuses on the confiscated specimen which makes up the nest with the babies' Protoceratops. Most of all Protoceratops in every growth process, have been discovered from the Djadokhta Formation in the Gobi desert. This formation crops out at Tugrikin Shireh and Bayn Dzak in the central part of the Gobi desert, and is derived from medium- to fine-grained sand mainly composed of quartz grains, of which sedimentary environments should be obvious to be eolian. The formation age of the sand beds at Tugrikin Shireh and Bayn Dzak has been estimated to be Middle Campanian. CL spectra of quartz have been demonstrated to show different features between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins, suggesting the spectra reflect the condition of the quartz formation and the local environment. Therefore, we have applied the CL characterization of quartz grains to the evaluation of the provenance of the desert sediments. The quartz grains after sieving (#60-80 mesh size) were embedded in the brass holders with non-luminescent epoxy resin, and their surfaces were polished with 1 μm diamond abrasive. Color CL images obtained by the Luminoscope exhibit blue, violet and red emissions in the grains, suggesting various types of emission centers in the quartz. SEM-CL analysis was conducted using an SEM (JSM-5410) combined with a grating monochromator (Mono CL2) to measure

  10. Cathodoluminescence plasmon microscopy

    NARCIS (Netherlands)

    Kuttge, M.

    2009-01-01

    Surface plasmon polaritons (SPPs) are electromagnetic waves that are strongly coupled to the collective oscillation of free electrons at an interface between a dielectric and a metal. Strong confinement of the electromagnetic field and tunability of SPP dispersion allow two-dimensional optics. This

  11. Chemical and physical studies of chondrites. X - Cathodoluminescence and phase composition studies of metamorphism and nebular processes in chondrules of type 3 ordinary chondrites

    Science.gov (United States)

    Dehart, John M.; Lofgren, Gary E.; Jie, LU; Benoit, Paul H.; Sears, Derek W. G.

    1992-01-01

    The cathodoluminescence (CL) characteristics of eight type-3 ordinary chondrites and one L5 chondrite were investigated with particular emphasis on detailed compositions of the relevant phases in four of these chondrites: Semarkona (type-3.0); Krymka (3.1); Allan Hills A77214 (3.5); and Dhajala (3.8). By sorting the chondrules into eight groups according to the CL of mesostasis and to certain compositional criteria and by determining the number of chondrules in these groups as a function of petrological type, it was possible to deduce genetic/evolutionary sequences of the chondrules. It is shown that there are major compositional differences in chondrules, which account for their CL properties and the chondrule groups.

  12. In-situ analysis of optoelectronic properties of twin boundaries in AlGaAs by polarized cathodoluminescence spectroscopy in a TEM.

    Science.gov (United States)

    Ohno, Yutaka

    2010-08-01

    Optoelectronic properties of nanoscale twin boundaries (TBs) in indirect-gap AlGaAs layers were studied by polarized cathodoluminescence spectroscopy in a transmission electron microscope. TBs arranged orderly in a short range, i.e. four or more parallel TBs arranged at regular intervals of nanometre length, emitted an intense monochromatic light polarized parallel to the boundaries. The intensity and the photon energy of the light were examined at different temperatures with different electron fluxes, and the origin of the light was discussed based on a twinning superlattice model. According to the study, it was suggested that the photon energy is tunable by controlling the intervals of TBs, without changing the crystal structure and the composition.

  13. Direct evidence of single quantum dot emission from GaN islands formed at threading dislocations using nanoscale cathodoluminescence: A source of single photons in the ultraviolet

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Gordon, E-mail: Gordon.Schmidt@ovgu.de; Berger, Christoph; Veit, Peter; Metzner, Sebastian; Bertram, Frank; Bläsing, Jürgen; Dadgar, Armin; Strittmatter, André; Christen, Jürgen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg (Germany); Callsen, Gordon; Kalinowski, Stefan; Hoffmann, Axel [Institute of Solid State Physics, Technical University Berlin, 10623 Berlin (Germany)

    2015-06-22

    Intense emission from GaN islands embedded in AlN resulting from GaN/AlN quantum well growth is directly resolved by performing cathodoluminescence spectroscopy in a scanning transmission electron microscope. Line widths down to 440 μeV are measured in a wavelength region between 220 and 310 nm confirming quantum dot like electronic properties in the islands. These quantum dot states can be structurally correlated to islands of slightly enlarged thicknesses of the GaN/AlN quantum well layer preferentially formed in vicinity to dislocations. The quantum dot states exhibit single photon emission in Hanbury Brown-Twiss experiments with a clear antibunching in the second order correlation function at zero time delay.

  14. Cathodoluminescence and Cross-sectional Transmission Electron Microscopy Studies for Deformation Behaviors of GaN Thin Films Under Berkovich Nanoindentation

    Directory of Open Access Journals (Sweden)

    Teng I-Ju

    2008-01-01

    Full Text Available AbstractIn this study, details of Berkovich nanoindentation-induced mechanical deformation mechanisms of metal-organic chemical-vapor deposition-derived GaN thin films have been systematic investigated with the aid of the cathodoluminescence (CL and the cross-sectional transmission electron microscopy (XTEM techniques. The multiple “pop-in” events were observed in the load-displacement (P–h curve and appeared to occur randomly by increasing the indentation load. These instabilities are attributed to the dislocation nucleation and propagation. The CL images of nanoindentation show very well-defined rosette structures with the hexagonal system and, clearly display the distribution of deformation-induced extended defects/dislocations which affect CL emission. By using focused ion beam milling to accurately position the cross-section of an indented area, XTEM results demonstrate that the major plastic deformation is taking place through the propagation of dislocations. The present observations are in support to the massive dislocations activities occurring underneath the indenter during the loading cycle. No evidence of either phase transformation or formation of micro-cracking was observed by means of scanning electron microscopy and XTEM observations. We also discuss how these features correlate with Berkovich nanoindentation produced defects/dislocations structures.

  15. Interface properties of Si-SiO{sub 2}-Ta{sub 2}O{sub 5} structure by cathodoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A. P.; Dmitriev, V. A.; Drozd, V. E.; Prokofiev, V. A.; Filatova, E. O. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); Samarin, S. N. [St. Petersburg State University, St. Petersburg 198504 (Russian Federation); School of Physics, The University of Western Australia, Perth, Western Australia 6009 (Australia)

    2016-02-07

    We studied formation of the SiO{sub 2}-T{sub 2}O{sub 5} interface in the Si-SiO{sub 2}-Ta{sub 2}O{sub 5} structure using Cathodoluminescence Spectroscopy (CLS). Analyzing the evolution of CLS spectrum of the Si-SiO{sub 2} structure while depositing the Ta{sub 2}O{sub 5} layer allowed to estimate an optical transmittance of the Ta{sub 2}O{sub 5} layer and its band gap. Spectral features related to the formation of the SiO{sub 2}-Ta{sub 2}O{sub 5} interface were identified by comparison of the experimental CL spectrum of the Si-SiO{sub 2}-Ta{sub 2}O{sub 5} structure and its simulated counterpart. This formation involves a decomposition of silanol groups at the outer surface of the SO{sub 2} layer and creation of the Si{sub x}Ta{sub y}O-type layer containing luminescence centers with the emission band centered at 3 eV photon energy.

  16. Nanometer scale correlation of optical and structural properties of individual InGaN/GaN nanorods by scanning transmission electron microscope cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Marcus; Schmidt, Gordon; Veit, Peter; Petzold, Silke; Bertram, Frank; Christen, Juergen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Albert, Steven; Bengoechea-Encabo, Ana Maria; Sanchez-Garcia, Miguel Angel; Calleja, Enrique [ISOM e Departamento de Ingenieria Electronica, Universidad Politecnica de Madrid (Spain)

    2013-07-01

    A potential benefit of nanorods as light emitters, aside from their very high crystal quality, relies on better light extraction efficiency as compared to thin films, because of the high surface to volume ratio. In this study we present a direct nano-scale correlation of the optical properties with the actual crystalline structure of ordered InGaN/GaN nanorods using low temperature cathodoluminescence spectroscopy in a scanning transmission electron microscope (STEM-CL). Direct comparison of the high-angle annular dark field image with the simultaneously recorded panchromatic CL mapping at 15 K reveals a weak luminescence from the bottom GaN layer. We observe the highest CL intensity in the middle of the InGaN region. The spectral position of the InGaN emission shifts continuously red from the GaN/InGaN interface (λ=409 nm) to the NR top (λ=446 nm) due to lattice pulling effects and InGaN partial decomposition. Additionally, optical active basal stacking faults in the GaN layer emitting at 366 nm can be found.

  17. Distinction between amorphous and healed planar deformation features in shocked quartz using composite color scanning electron microscope cathodoluminescence (SEM-CL) imaging

    Science.gov (United States)

    Hamers, Maartje F.; Pennock, Gill M.; Herwegh, Marco; Drury, Martyn R.

    2016-10-01

    Planar deformation features (PDFs) in quartz are one of the most reliable and most widely used forms of evidence for hypervelocity impact. PDFs can be identified in scanning electron microscope cathodoluminescence (SEM-CL) images, but not all PDFs show the same CL behavior: there are nonluminescent and red luminescent PDFs. This study aims to explain the origin of the different CL emissions in PDFs. Focused ion beam (FIB) thin foils were prepared of specific sample locations selected in composite color SEM-CL images and were analyzed in a transmission electron microscope (TEM). The FIB preparation technique allowed a direct, often one-to-one correlation between the CL images and the defect structure observed in TEM. This correlation shows that composite color SEM-CL imaging allows distinction between amorphous PDFs on one hand and healed PDFs and basal Brazil twins on the other: nonluminescent PDFs are amorphous, while healed PDFs and basal Brazil twins are red luminescent, with a dominant emission peak at 650 nm. We suggest that the red luminescence is the result of preferential beam damage along dislocations, fluid inclusions, and twin boundaries. Furthermore, a high-pressure phase (possibly stishovite) in PDFs can be detected in color SEM-CL images by its blue luminescence.

  18. Cathodoluminescence properties of Tb{sup 3+}-doped Na{sub 3}YSi{sub 2}O{sub 7} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wenyu; Li, Songbo [Innermongolia University of Science and Technology, School of Chemistry and Chemical Engineering, Baotou (China); University of Science and Technology Beijing, School of Metallurgical and Ecological Engineering, Beijing (China); An, Shengli [University of Science and Technology Beijing, School of Metallurgical and Ecological Engineering, Beijing (China); Innermongolia University of Science and Technology, School of Material and Metallurgical Engineering, Baotou (China); Fan, Bin [Innermongolia University of Science and Technology, School of Chemistry and Chemical Engineering, Baotou (China)

    2013-05-15

    Tb{sup 3+}-doped Na{sub 3}YSi{sub 2}O{sub 7} phosphors were prepared by the sol-gel method and then characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy, and cathodoluminescence spectroscopy. The XRD results reveal that the Tb{sup 3+} ions have been introduced as dopants into the Na{sub 3}YSi{sub 2}O{sub 7} host lattice. Under low-voltage electron beam excitation, the phosphors exhibit the characteristic emissions of Tb{sup 3+} ({sup 5} D{sub 3,4}{yields}{sup 7} F{sub J}, J=3-6 transitions). The luminescence color of the phosphors can be tuned from greenish-blue to bluish-green and to green by controlling the Tb {sup 3+} concentration within the 0.0005-0.15 (x value). The optimum Tb {sup 3+} doping concentration is 10 mol%, and the ''dead voltage'' is approximately 1.35 kV. All results indicate that the sample is a phosphor candidate for field-emission displays. (orig.)

  19. Correlative near-infrared light and cathodoluminescence microscopy using Y2O3:Ln, Yb (Ln = Tm, Er) nanophosphors for multiscale, multicolour bioimaging

    Science.gov (United States)

    Fukushima, S.; Furukawa, T.; Niioka, H.; Ichimiya, M.; Sannomiya, T.; Tanaka, N.; Onoshima, D.; Yukawa, H.; Baba, Y.; Ashida, M.; Miyake, J.; Araki, T.; Hashimoto, M.

    2016-05-01

    This paper presents a new correlative bioimaging technique using Y2O3:Tm, Yb and Y2O3:Er, Yb nanophosphors (NPs) as imaging probes that emit luminescence excited by both near-infrared (NIR) light and an electron beam. Under 980 nm NIR light irradiation, the Y2O3:Tm, Yb and Y2O3:Er, Yb NPs emitted NIR luminescence (NIRL) around 810 nm and 1530 nm, respectively, and cathodoluminescence at 455 nm and 660 nm under excitation of accelerated electrons, respectively. Multimodalities of the NPs were confirmed in correlative NIRL/CL imaging and their locations were visualized at the same observation area in both NIRL and CL images. Using CL microscopy, the NPs were visualized at the single-particle level and with multicolour. Multiscale NIRL/CL bioimaging was demonstrated through in vivo and in vitro NIRL deep-tissue observations, cellular NIRL imaging, and high-spatial resolution CL imaging of the NPs inside cells. The location of a cell sheet transplanted onto the back muscle fascia of a hairy rat was visualized through NIRL imaging of the Y2O3:Er, Yb NPs. Accurate positions of cells through the thickness (1.5 mm) of a tissue phantom were detected by NIRL from the Y2O3:Tm, Yb NPs. Further, locations of the two types of NPs inside cells were observed using CL microscopy.

  20. Effect of Size-Dependent Thermal Instability on Synthesis of Zn2 SiO4-SiOx Core–Shell Nanotube Arrays and Their Cathodoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Dierre Benjamin

    2010-01-01

    Full Text Available Abstract Vertically aligned Zn2SiO4-SiOx(x < 2 core–shell nanotube arrays consisting of Zn2SiO4-nanoparticle chains encapsulated into SiOx nanotubes and SiOx-coated Zn2SiO4 coaxial nanotubes were synthesized via one-step thermal annealing process using ZnO nanowire (ZNW arrays as templates. The appearance of different nanotube morphologies was due to size-dependent thermal instability and specific melting of ZNWs. With an increase in ZNW diameter, the formation mechanism changed from decomposition of “etching” to Rayleigh instability and then to Kirkendall effect, consequently resulting in polycrystalline Zn2SiO4-SiOx coaxial nanotubes, single-crystalline Zn2SiO4-nanoparticle-chain-embedded SiOx nanotubes, and single-crystalline Zn2SiO4-SiOx coaxial nanotubes. The difference in spatially resolved optical properties related to a particular morphology was efficiently documented by means of cathodoluminescence (CL spectroscopy using a middle-ultraviolet emission at 310 nm from the Zn2SiO4 phase.

  1. Core-shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping.

    Science.gov (United States)

    Tchernycheva, M; Neplokh, V; Zhang, H; Lavenus, P; Rigutti, L; Bayle, F; Julien, F H; Babichev, A; Jacopin, G; Largeau, L; Ciechonski, R; Vescovi, G; Kryliouk, O

    2015-07-21

    We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p-n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC signal toward the nanowire top is accompanied by an increase of the CL intensity. This effect is interpreted as a consequence of the In and Al gradients in the quantum well and in the electron blocking layer, which influence the carrier extraction efficiency. The interface between the nanowire core and the radially grown layer is shown to produce in some cases a transitory EBIC signal. This observation is explained by the presence of charged traps at this interface, which can be saturated by electron irradiation.

  2. Local carrier recombination and associated dynamics in m-plane InGaN/GaN quantum wells probed by picosecond cathodoluminescence

    Science.gov (United States)

    Zhu, Tongtong; Gachet, David; Tang, Fengzai; Fu, Wai Yuen; Oehler, Fabrice; Kappers, Menno J.; Dawson, Phil; Humphreys, Colin J.; Oliver, Rachel A.

    2016-12-01

    We report on spatially resolved and time-resolved cathodoluminescence (CL) studies of the recombination mechanisms of InGaN/GaN quantum wells (QWs) grown by metal-organic vapour phase epitaxy on bulk m-plane Ammono GaN substrates. As a result of the 2° miscut of the GaN substrate, the sample surface exhibits step bunches, where semi-polar QWs with a higher indium concentration than the planar m-plane QWs form during the QW growth. Spatially resolved time-integrated CL maps under both continuous and pulsed excitation show a broad emission band originating from the m-plane QWs and a distinct low energy emission originating from the semi-polar QWs at the step bunches. High resolution time-resolved CL maps reveal that when the m-QWs are excited well away from the step bunches the emission from the m-plane QWs decays with a time constant of 350 ps, whereas the emission originating semi-polar QWs decays with a longer time constant of 489 ps. The time constant of the decay from the semi-polar QWs is longer due to the separation of the carrier wavefunctions caused by the electric field across the semi-polar QWs.

  3. Correlation between the structural and cathodoluminescence properties in InGaN/GaN multiple quantum wells with large number of quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jing; Zhao, Degang, E-mail: dgzhao@red.semi.ac.cn; Jiang, Desheng; Chen, Ping; Zhu, Jianjun; Liu, Zongshun; Le, Lingcong; He, Xiaoguang; Li, Xiaojing [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, PO BOX 912, Beijing 100083 (China); Wang, Hui; Yang, Hui [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Jahn, Uwe [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany)

    2014-09-01

    Cathodoluminescence (CL) characteristics on 30-period InGaN/GaN multiple quantum well (MQW) solar cell structures are investigated, revealing the relationship between optical and structural properties of the MQW structures with a large number of quantum wells. In the bottom MQW layers, a blueshift of CL peak along the growth direction is found and attributed to the decrease of indium content due to the compositional pulling effect. An obvious split of emission peak and a redshift of the main emission energy are found in the top MQW layers when the MQW grows above the critical layer thickness. They are attributed to the segregation of In-rich InGaN clusters rather than the increase of indium content in quantum well layer. The MQW structure is identified to consist of two regions: a strained one in the bottom, where the indium content is gradually decreased, and a partly relaxed one in the top with segregated In-rich InGaN clusters.

  4. Local Field Enhancement-Induced Enriched Cathodoluminescence Behavior from CuI-RGO Nanophosphor Composite for Field-Emission Display Applications.

    Science.gov (United States)

    Saha, Subhajit; Roy, Rajarshi; Das, Swati; Sen, Dipayan; Ghorai, Uttam Kumar; Mazumder, Nilesh; Chattopadhyay, Kalyan Kumar

    2016-09-28

    Field-emission displays (FEDs) constitute one of the major foci of the cutting edge materials research because of the increasingly escalating demand for high-resolution display panels. However, poor efficiencies of the concurrent low voltage cathodoluminescence (CL) phosphors have created a serious bottleneck in the commercialization of such devices. Herein we report a novel CuI-RGO composite nanophosphor that exhibits bright red emission under low voltage electron beam excitation. Quantitative assessment of CL spectra reveals that CuI-RGO nanocomposite phosphor leads to the 4-fold enhancement in the CL intensity as compared to the pristine CuI counterpart. Addition of RGO in the CuI matrix facilitates efficient triggering of luminescence centers that are activated by local electric field enhancement at the CuI-RGO contact points. In addition, conducting RGO also reduces the negative loading problem on the surface of the nanophosphor composite. The concept presented here opens up a novel generic route for enhancing CL intensity of the existing (nano)phosphors as well as validates the bright prospects of the CuI-RGO composite nanophosphor in this rapidly growing field.

  5. Photoluminescence and cathodoluminescence properties of Eu{sup 3+} ions activated AMoO{sub 4} (A = Mg, Ca, Sr, Ba) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Du, Peng; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2015-10-15

    Highlights: • Under 393 nm excitation, strong red emission located at 615 nm was observed in all the samples. • The Eu{sup 3+}-activated CaMoO{sub 4} phosphor exhibited the strongest PL properties. • The CIE chromaticity coordinate of Eu{sup 3+}-activated CaMoO{sub 4} phosphor was (0.647,0.352). • The color purity of Eu{sup 3+}-activated CaMoO{sub 4} phosphor was 92.8%. • Strong CL properties were observed in the Eu{sup 3+}-activated CaMoO{sub 4} phosphor. - Abstract: Eu{sup 3+}-activated AMoO{sub 4} (A = Mg, Ca, Sr, Ba) phosphors were synthesized by a solid-state reaction method. Photoluminescence and cathodoluminescence (CL) spectra as well as X-ray diffraction patterns were measured to characterize the fabricated samples. Under 393 nm excitation, strong red emissions located at ∼615 nm corresponding to the {sup 5}D{sub 0} → {sup 7}F{sub 2} transition of Eu{sup 3+} ions were observed in all the samples. Compared with other Eu{sup 3+} ions activated AMoO{sub 4} (A = Mg, Sr, Ba) phosphors, Eu{sup 3+}-activated CaMoO{sub 4} phosphor exhibited the strongest red emission intensity with better Commission Internationale de L’Eclairage chromaticity coordinate and higher color purity. Furthermore, the CL results indicated that the Eu{sup 3+}-activated CaMoO{sub 4} phosphor had excellent luminescence properties.

  6. Defects in a mixed-habit Yakutian diamond: Studies by optical and cathodoluminescence microscopy, infrared absorption, Raman scattering and photoluminescence spectroscopy

    Science.gov (United States)

    Lang, A. R.; Bulanova, G. P.; Fisher, D.; Furkert, S.; Sarua, A.

    2007-12-01

    Widespread occurrences in the crystallisation history of natural diamonds are epochs of mixed-habit growth in which normal {1 1 1}-faceted growth is accompanied by non-faceted growth on curved surfaces of mean orientation ˜{1 0 0}, termed 'cuboid'. This paper analyses mixed-habit-related phenomena in a near-central, (1 1 0)-polished slice of an octahedron from the Mir pipe, previously studied principally by SIMS probes analysing N impurity content and C and N isotope composition. In the present work, newly studied features include dislocation content, fine structure in cathodoluminescence (CL) patterns, refined IR absorption data, Raman and photoluminescence (PL) microspectroscopy and microscopy of internal non-diamond bodies. Topographic imaging and spectroscopic techniques traced the specimen's morphological evolution from a cubo-octahedral core containing complex relative development of {1 1 1} and cuboid sectors, both populated by graphite crystallites, diameters up to ˜5 μm, lying on all diamond host {1 1 1}. Coherently overgrowing the core was a zone of widely but smoothly varying relative development of {1 1 1} and cuboid sectors, both on birefringence evidence dislocation-free, emitting strongly from cuboid sectors the PL spectra associated with Ni-N-vacancy complexes. An enclosing octahedral shell of solely {1 1 1} lamellae terminated mixed-habit growth. High-resolution FTIR absorption measurements of I( B'), the integrated absorption due to {1 0 0}-platelet defects, showed from its absence or weakness that total or substantial platelet degradation had taken place in the mixed-habit zones, indicating that these had undergone conditions close to the diamond-graphite phase boundary in their history.

  7. Geochemistry of the Spor Mountain rhyolite, western Utah, as revealed by laser ablation ICP-MS, cathodoluminescence, and electron microprobe analysis

    Science.gov (United States)

    Dailey, S. R.; Christiansen, E. H.; Dorais, M.; Fernandez, D. P.

    2015-12-01

    The Miocene topaz rhyolite at Spor Mountain in western Utah hosts one of the largest beryllium deposits in the world and was responsible for producing 85% of the beryllium mined worldwide in 2010 (Boland, 2012). The Spor Mountain rhyolite is composed primarily of Ca-poor plagioclase (An8), sodic sanidine (Or40), Fe-rich biotite (Fe/(Fe+Mg)>0.95; Al 1.2-1.4 apfu), and Ti-poor quartz, along with several trace-element rich accessory phases including zircon, monazite, thorite, columbite, and allanite. Cathodoluminescence (CL) studies of quartz show oscillatory zoning, with 80% of the examined crystals displaying euhedral edges and slightly darker rims. CL images were used to guide laser ablation (LA) ICP-MS analysis of quartz, along with analyses of plagioclase, sanidine, biotite, and glass. Ti concentrations in quartz are 20±6 ppm; there is no quantifiable variation of Ti from core to rim within the diameter of the laser spot (53 microns). Temperatures, calculated using Ti in quartz (at 2 kb, aTiO2=0.34), vary between 529±10 C (Thomas et al., 2011), 669±13 C (Huang and Audetat, 2012), and 691±13 C (Wark and Watson, 2006). Two feldspar thermometry yield temperatures of 686±33 C (Elkins and Grove, 1990) and 670±41 C (Benisek et al., 2010). Zr saturation temperatures (Watson and Harrison, 1983) average 711±28 C. Analysis of the glass reveal the Spor Mountain rhyolite is greatly enriched in rare elements (i.e. Li, Be, F, Ga, Rb, Nb, Mo, Sn, and Ta) compared to average continental crust (Rudnick and Gao, 2003). Be in the glass can have as much as 100 ppm, nearly 50 times the concentration in continental crust. REE partition coefficients for sanidine are 2 to 3 times higher in the Spor Mountain rhyolite when compared to other silicic magmas (Nash and Crecraft, 1985; Mahood and Hildreth, 1983), although plagioclase tends to have lower partition coefficients; biotite has lower partition coefficients for LREE and higher partition coefficients for HREE. The patterns of

  8. SEM-Cathodoluminescence and fluid inclusion study of quartz veins in Hugo Dummett porphyry Cu-Au deposit,South Mongolia

    Science.gov (United States)

    Sanjaa, M.; Fujimaki, H.; Ken-Ichiro, H.

    2010-12-01

    The Hugo Dummett porphyry copper-gold deposit in Oyu Tolgoi, South Mongolia is a high-sulfidation type deposit which consists of Cu-Au bearing quartz veins. Cathodoluminescence (CL) analysis using scanning electron microscope (SEM) and fluid inclusion microthermometer were performed to elucidate the relationship between CL structures, fluid inclusion microthermometer of different quartz generations, and ore forming process of the Hugo Dummett deposit. Hydrothermal quartz from quartz-sulfide veins in the porphyry Cu-Au deposit in Hugo Dummett, revealing the following textures: (1) euhedral growth zones (2) embayed and rounded CL-bright cores, with CL-dark and CL-gray overgrowths, (3) concentric and non concentric growth zones, and (4) CL dark/bright microfractures. These textures indicate that many veins have undergone fracturing, growth of quartz into fluid-filled space and quartz dissolution of quartz. SEM-CL imaging indicates vein quartz in the Hugo Dummett deposit, initially grew as individual CL-bright crystals 356 ± 10°C liquid-reservoir (average Th value for fluid inclusions in the crystal cores is 359°C). In contract, SEM-CL imaging shows the edges of the micron-scale growth zones of varying CL intensity, reflecting quartz precipitation at some later time, when the Hugo Dummett deposit hydrothermal system had cooled, when reservoir conditions were about 211 ± 25°C (average Th value of 212°C). Crystal growth is SEM-CL evidence of the vein quartz having been partly dissolved. Pressure change has a large effect on quartz solubility and may have been responsible for quartz dissolution and precipitation textures in the cooling hydrothermal system. CL-dark microfractures homogenization temperatures lower 169 ± 16°C (average Th value 170°C) than CL bright and CL gray. Temperature and pressure of the mineralized fluid estimates a pressure of formation of 0.3-0.5 kbar (lithostatic), was formed at approximately 2 km depth, as well as a formation temperature

  9. Cathodoluminescence of Irradiated Hafnium Dioxide

    Science.gov (United States)

    2011-03-01

    conditions on the spectra of these samples. Problem Statement The goals of this thesis are: (1) to examine the radiation hardness of hafnium dioxide...peaks are also seen in two other materials that were examined in the same chamber, namely lithium tetraborate and aluminum gallium nitride . Spectra...untainted spectra. Significance of Research For the radiation doses to which HfO2 was exposed, it seems that HfO2 is radiation hard ; therefore, this

  10. Hydrothermal Evolution of the Giant Cenozoic Kadjaran porphyry Cu-Mo deposit, Tethyan metallogenic belt, Armenia, Lesser Caucasus: mineral paragenetic, cathodoluminescence and fluid inclusion constraints

    Science.gov (United States)

    Hovakimyan, Samvel; Moritz, Robert; Tayan, Rodrik; Rezeau, Hervé

    2016-04-01

    stockwork. One of them is the east-west-oriented 6th vein zone in the northern part of the deposit, which contains quartz-molybdenite veins and late quartz-galena-sphalerite veins. This is interpreted as a telescoping between porphyry and epithermal environments. It is supported by microscopic studies of mineral paragenesis, which reveal the presence of enargite and tennantite-tetrahedrite, luzonite, sphalerite, and galena, generally in a gangue of quartz, followed by a late carbonate and gypsum stage. On-going fluid inclusion studies are being carried out on quartz samples from the different mineralization stages. Five types of fluid inclusions were distinguished according to their nature, bubble size, and daughter mineral content: vapor-rich, aqueous-carbonic, brine, polyphase brine and liquid-rich inclusions. Cathodoluminescence images from the porphyry veins reveal four generations of quartz. Molybdenite and chalcopyrite are associated with two different dark luminescent quartz generations, which contain typical brine, aqueous-carbonic and vapour-rich H2O fluid inclusions, with some of them coexisting locally as boiling assemblages. Epithermal veins are mainly characterized by liquid-rich H2O fluid inclusions. Microthermometric studies of fluid inclusions reveal a major difference in homogenisation temperatures between the early quartz-molybdenite- chalcopyrite stage (Thtotal between 3600 and 4250C) and the late quartz-galena-sphalerite vein stage (Thtotal 300-2700C), which is attributed to the transition from a porphyry to an epithermal environment in the Kadjaran deposit.

  11. Origin of ~2.5 Ga potassic granite from the Nellore Schist Belt, SE India: textural, cathodoluminescence, and SHRIMP U-Pb data

    Science.gov (United States)

    Vijaya Kumar, K.; Ernst, W. G.; Leelanandam, C.; Wooden, J. L.; Grove, M. J.

    2011-10-01

    In a geochemical and geochronological investigation of Archean and Proterozoic magmatism in the Nellore Schist Belt, we conducted SHRIMP U-Pb analyses of zircons from two cospatial granitic bodies at Guramkonda and Vendodu. The former is a Ba- and Sr-rich hornblende-bearing tonalite, whereas the latter is a Rb-, Zr-, Pb-, Th-, U-, and REE-rich biotite-bearing leucogranite. The Guramkonda tonalite displays a restitic texture with remnants of trapped granitic melt, whereas the Vendodu leucogranite contains residual/partially melted plagioclase grains. Both rock types contain two generations of zircon: tonalite contains a group of euhedral zoned zircons enclosed within plagioclase and a group of subhedral patchy zircons associated with trapped melt (quartz + feldspar matrix), and leucogranite also contains a group of doubly terminated euhedral zircons included within orthoclase as well as a group of zircons with visible cores mantled by later rim growth. Cathodoluminescence images also clearly document two distinctly textured varieties of zircon: the tonalite contains a population characterized by narrowly spaced uninterrupted oscillatory zoning and a second population lacking zoning but exhibiting a random distribution of dark (U-rich) and light (U-poor) regions; the leucogranite contains U-rich zoned zircons and U-poor zircon cores mantled by U-rich rims. The REE chemistry of zircon cores from the Vendodu leucogranite is very similar to the REE of zoned zircons from the Guramkonda tonalite. Zircon ages from both plutons exhibit bimodal distributions in U-Pb concordia diagrams. The tonalite defines an age of 2,521 Ma ± 5 Ma for zoned magmatic zircons and 2,485 Ma ± 5 Ma for unzoned newly precipitated zircons, whereas the leucogranite has an age of 2,518 Ma ± 5 Ma for U-poor zircon cores (relics of the tonalite pluton) and 2,483 Ma ± 3 Ma for U-rich zoned magmatic zircons. The trace element geochemistry of the ~2,520 Ma zircons is distinctly different from the ~2

  12. Deciphering igneous and metamorphic events in high-grade rocks of the Wilmington complex, Delaware: Morphology, cathodoluminescence and backscattered electron zoning, and SHRIMP U-Pb geochronology of zircon and monazite

    Science.gov (United States)

    Aleinikoff, J.N.; Schenck, W.S.; Plank, M.O.; Srogi, L.A.; Fanning, C.M.; Kamo, S.L.; Bosbyshell, H.

    2006-01-01

    High-grade rocks of the Wilmington Complex, northern Delaware and adjacent Maryland and Pennsylvania, contain morphologically complex zircons that formed through both igneous and metamorphic processes during the development of an island-arc complex and suturing of the arc to Laurentia. The arc complex has been divided into several members, the protoliths of which include both intrusive and extrusive rocks. Metasedimentary rocks are interlayered with the complex and are believed to be the infrastructure upon which the arc was built. In the Wilmingto n Complex rocks, both igneous and metamorphic zircons occur as elongate and equant forms. Chemical zoning, shown by cathodoluminescence (CL), includes both concentric, oscillatory patterns, indicative of igneous origin, and patchwork and sector patterns, suggestive of metamorphic growth. Metamorphic monazites are chemically homogeneous, or show oscillatory or spotted chemical zoning in backscattered electron images. U-Pb geochronology by sensitive high resolution ion microprobe (SHRIMP) was used to date complexly zoned zircon and monazite. All but one member of the Wilmington Complex crystallized in the Ordovician between ca. 475 and 485 Ma; these rocks were intruded by a suite of gabbro-to-granite plutonic rocks at 434 ?? Ma. Detrital zircons in metavolcanic and metasedimentary units were derived predominantly from 0.9 to 1.4 Ga (Grenvillian) basement, presumably of Laurentian origin. Amphibolite to granulite facies metamorphism of the Wilmington Complex, recorded by ages of metamorphic zircon (428 ?? 4 and 432 ?? 6 Ma) and monazite (429 ?? 2 and 426 ?? 3 Ma), occurred contemporaneously with emplacement of the younger plutonic rocks. On the basis of varying CL zoning patterns and external morphologies, metamorphic zircons formed by different processes (presumably controlled by rock chemistry) at slightly different times and temperatures during prograde metamorphism. In addition, at least three other thermal episodes are

  13. Temperature dependence of exciton-surface plasmon polariton coupling in Ag, Au, and Al films on In{sub x}Ga{sub 1−x}N/GaN quantum wells studied with time-resolved cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Estrin, Y.; Rich, D. H., E-mail: danrich@bgu.ac.il [Department of Physics and The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O.B 653, Beer-Sheva 84105 (Israel); Keller, S.; DenBaars, S. P. [Electrical and Computer Engineering and Materials Departments, University of California, Santa Barbara, California 93111 (United States)

    2015-01-28

    The optical properties and coupling of excitons to surface plasmon polaritons (SPPs) in Ag, Au, and Al-coated In{sub x}Ga{sub 1−x}N/GaN multiple and single quantum wells (SQWs) were probed with time-resolved cathodoluminescence. Excitons were generated in the metal coated SQWs by injecting a pulsed high-energy electron beam through the thin metal films. The Purcell enhancement factor (F{sub p}) was obtained by direct measurement of changes in the temperature-dependent radiative lifetime caused by the SQW exciton-SPP coupling. Three chosen plasmonic metals of Al, Ag, and Au facilitate an interesting comparison of the exciton-SPP coupling for energy ranges in which the SP energy is greater than, approximately equal to, and less than the excitonic transition energy for the InGaN/GaN QW emitter. A modeling of the temperature dependence of the Purcell enhancement factor, F{sub p}, included the effects of ohmic losses of the metals and changes in the dielectric properties due to the temperature dependence of (i) the intraband behavior in the Drude model and (ii) the interband critical point transition energies which involve the d-bands of Au and Ag. We show that an inclusion of both intraband and interband effects is essential when calculating the ω vs k SPP dispersion relation, plasmon density of states (DOS), and the dependence of F{sub p} on frequency and temperature. Moreover, the “back bending” in the SPP dispersion relation when including ohmic losses can cause a finite DOS above ω{sub sp} and lead to a measurable F{sub p} in a limited energy range above ω{sub sp}, which can potentially be exploited in plasmonic devices utilizing Ag and Au.

  14. Emission properties of hydrothermal Yb{sup 3+}, Er{sup 3+} and Yb{sup 3+}, Tm{sup 3+}-codoped Lu{sub 2}O{sub 3} nanorods: upconversion, cathodoluminescence and assessment of waveguide behavior

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, Elixir William; Pujol, MarIa Cinta; DIaz, Francesc [Fisica i Cristal.lografia de Materials, Universitat Rovira i Virgili, Campus Sescelades c/ Marcel.lI Domingo s/n, E-43007 Tarragona (Spain); Choi, Soo Bong; Rotermund, Fabian [Division of Energy Systems Research, Ajou University, 443-749 Suwon (Korea, Republic of); Park, Kyung Ho [Korea Advanced Nano Fab Center, 443-270 Suwon (Korea, Republic of); Jeong, Mun Seok [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, 500-712 Gwangju (Korea, Republic of); Cascales, Concepcion, E-mail: ccascales@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, c/Sor Juana Ines de la Cruz, 3 Cantoblanco, E-28049 Madrid (Spain)

    2011-02-18

    Yb{sup 3+} and Ln{sup 3+} (Ln{sup 3+} = Er{sup 3+} or Tm{sup 3+}) codoped Lu{sub 2}O{sub 3} nanorods with cubic Ia3-bar symmetry have been prepared by low temperature hydrothermal procedures, and their luminescence properties and waveguide behavior analyzed by means of scanning near-field optical microscopy (SNOM). Room temperature upconversion (UC) under excitation at 980 nm and cathodoluminescence (CL) spectra were studied as a function of the Yb{sup +} concentration in the prepared nanorods. UC spectra revealed the strong development of Er{sup 3+4}F{sub 9/2} {yields} 4I{sub 15/2} (red) and Tm{sup 3+1}G{sub 4} {yields} {sup 3}H{sub 6} (blue) bands, which became the pre-eminent and even unique emissions for corresponding nanorods with the higher Yb{sup 3+} concentration. Favored by the presence of large phonons in current nanorods, UC mechanisms that privilege the population of {sup 4}F{sub 9/2} and {sup 1}G{sub 4} emitting levels through phonon-assisted energy transfer and non-radiative relaxations account for these observed UC luminescence features. CL spectra show much more moderate development of the intensity ratio between the Er{sup 3+4}F{sub 9/2} {yields}{sup 4}I{sub 15/2} (red) and {sup 2}H{sub 11/2}, {sup 4}S{sub 3/2} {yields} {sup 4}I{sub 15/2} (green) emissions with the increase in the Yb{sup 3+} content, while for Yb{sup 3+}, Tm{sup 3+}-codoped Lu{sub 2}O{sub 3} nanorods the dominant CL emission is Tm{sup 3+1}D{sub 2} {yields} {sup 3}F{sub 4} (deep-blue). Uniform light emission along Yb{sup 3+}, Er{sup 3+}-codoped Lu{sub 2}O{sub 3} rods has been observed by using SNOM photoluminescence images; however, the rods seem to be too thin for propagation of light.

  15. Cement stratigraphy: Image probes of cathodoluminescent facies.

    OpenAIRE

    Vuillemin, Aurèle; Ndiaye, Mapathe; Martini, Rossana; Davaud, Eric Jean

    2011-01-01

    Cement stratigraphy of carbonates aims to establish the chronology of processes involved in the rock diagenesis. Regional cement stratigraphy allows correlations and understanding of the petrological heterogeneities in reservoirs and aquifers, but is a long and rigorous approach. This article exposes a methodology of image analysis that facilitates the spatial correlation of diagenetic events in carbonate rocks. Based on the statistical comparison of signals extracted from the red spectrum em...

  16. Cathodoluminescence investigation of relaxor-based ferroelectrics Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} (PMN-0.3PT) single-crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ge Wanyin, E-mail: wanyinge@gmail.co [Ceramic Physics Laboratory and Research Institute for Nanoscience (RIN), Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto (Japan); Zhu Wenliang [Ceramic Physics Laboratory and Research Institute for Nanoscience (RIN), Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto (Japan); Pezzotti, Giuseppe, E-mail: pezzotti@kit.ac.j [Ceramic Physics Laboratory and Research Institute for Nanoscience (RIN), Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto (Japan)

    2010-01-01

    Relaxor-based ferroelectric lead magnesium niobate-lead titanate Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} (PMN-PT) possesses ultrahigh electromechanical coefficients near the morphotropic phase boundary (MPB). In this paper, the electro-stimulated emission characteristics of a [0 0 1]-oriented PMN-0.3PTsingle-crystal were studied using high resolution cathodoluminescence (CL) spectroscopy at room temperature. Four luminescence bands were observed in the range of 200-900 nm and they were assigned to polaron, nanometre cluster emission, interband emission and structure-related emission. Besides, it was found that the residual stress field ahead of a crack tip of a Vickers indentation had a considerable influence on these luminescence bands. The relationship between the intensities of CL bands and the residual stress field has been investigated and discussed in this paper.

  17. Probing light emission at the nanoscale with cathodoluminescence

    NARCIS (Netherlands)

    B.J.M. Brenny

    2016-01-01

    Nanophotonics, the study of light at the nanoscale, is a vibrant field of research with a wide variety of applications. To mold and control light at the nanoscale, it is essential to measure and characterize nanostructures and their interaction with light at this subwavelength scale. This thesis des

  18. Cathodoluminescence studies of defects and piezoelectric fields in GaN

    CERN Document Server

    Henley, S

    2002-01-01

    dislocations were observed to generate in-plane dislocation half-loops, which moved under the influence of the stress present. These dislocation half loops were shown to act as non-radiative recombination centres. observed in CL and photoluminescence (PL) experiments. It is suggested that separation across the well of charge carriers of opposite signs screened the piezoelectric field. The blue shift of the QW luminescence was observed to remain after high electron dose irradiation in the SEM. This effect was not observed in PL measurements after high laser power exposure. The CL blue shift could be removed by irradiation with a UV lamp. It was shown that the minority carrier diffusion length (MCDL) increased from 200nm at low electron beam irradiation doses to 330nm after higher dose irradiation in the SEM. It is proposed that the change in the MCDL and the prolonged nature of the blue shift of the QW CL peak can be explained by the filling of trap states in the vicinity of the QW. It is suggested that these ...

  19. Cathodoluminescence and Thermoluminescence of Undoped LTB and LTB:A (A = Cu, Ag, Mn)

    Science.gov (United States)

    2013-03-01

    lithium tetraborate.” PhD dissertation, Air Force Institute of Technology, 2010. [8] J. G. Gualtieri, J. A. Kosinski, W. D. Wilber , Y. Lu, S. T. Lin...R6095. Shizuoka- ken Japan: Hamamatsu Photonics K. K., 1996. [25] Stanford Research Systems. Operator’s Manual: Multichannel Scaler/Averager

  20. Band Gap Transition Studies of U:ThO2 Using Cathodoluminescence

    Science.gov (United States)

    2014-03-27

    evidence of the midgap O 2p to U 5f quadrupole transition and O 2p to U 6d transition at 5 eV. iv To my Lord Jesus Christ , through whom all things are...possible v Acknowledgments First and foremost, I would like to thank my Lord and Savior Jesus Christ for granting me the resolve and intellect to finish...walk from low to high (or vice versa) and then returning to the original temperature. CL spectra can then be compared between the sample as the

  1. High Resolution Cathodoluminescence of Yellow and Waterclear CVD Polycrystalline ZnS.

    Science.gov (United States)

    1983-12-01

    Japanese Journal of Applied Physics , 20...55. Kobayashi, H. et al. "Excitation Mechanism of Electro- luminescent ZnS Thin Films Doped with Rare-Earth Ions." Japanese Journal of Applied Physics , 13...Al Phosphor." Japanese Journal of Applied Physics , 19 no 9: 1647-53 (September 1980). 112 _W0%. . . 57. Kukimoto, H., S. Oda, and T.

  2. Cathodoluminescent bimineralic ooids from the Pleistocene of the Florida continental shelf

    Science.gov (United States)

    Major, R. P.; Halley, Robert B.; Lukas, Karen J.

    1988-01-01

    A bored and encrusted late Pleistocene ooid grainstone was recovered from the seafloor at a depth of approximately 40 m on the outer continental shelf of eastern Florida. Ooid cortices are dominantly bimineralic, generally consisting of inner layers of radial magnesian calcite and outer layers of tangential aragonite. Ooid nuclei are dominantly rounded cryptocrystalline grains, although quartz grains and a variety of skeletal grains also occur as nuclei. Ooids are partially cemented by blocky calcite, and interparticle porosity is partially filled by micrite.

  3. Hydrothermal synthesis and cathodoluminescence of ZnO crystalline powders and coatings

    Science.gov (United States)

    Dem'yanets, L. N.; Li, L. E.; Uvarova, T. G.

    2006-01-01

    Nanocrystalline ZnO powders and coatings of ZnO were obtained under soft hydrothermal conditions. The growth systems contained various ZnO-precursors (as-prepared Zn-hydroxide, chemical ZnO, Zn(NO 3) 2), solvents (LiOH, KOH, NH 4OH) and Zn-substrate. ZnO growth morphology was found to depend on the chemical composition of the solvent: Li + suppresses the growth of (0 0 0 1) faces, NH 4+ promotes it. Aspect ratio of crystals is controlled by solvent type and concentration. Luminescent properties have been studied using impulse laser or cathode excitation. The ratio IUV/ IVIS in luminescence spectra was found to depend on the excitation mode. Laser excitation allows to obtain UV-band with higher intensity in comparison with cathode excitation. The most intensive UV luminescence was found for polycrystalline coatings on Zn-substrates obtained in the systems with KOH as a solvent. Mathematic treatment of the ICL spectra was carried out; the wide VIS-band was found to consist of the series of overlapping bands. UV luminescence quenching centers were suggested to be connected mainly with the irradiation in VIS-region with cλ>700 nm.

  4. The Cathodoluminescence of Cleartran: A Novel Form of Polycrystalline ZnS.

    Science.gov (United States)

    1986-12-01

    Theory and Summary of Previous Work. . . . . . . 11 Crystallography of ZnS . . . . . . . . . . . . 11 Crystal Growth Techniques. . . . . . . . . . . 15...perceived that his crystals were phosphorescent. It was not until 1888 that Verneuil ascribed the phosphorescence to the presence of a "foreign...photoconductivity studies of CdS (3). At that time, crystal growth techniques began to improve and single crystals of a variety of II-VI compounds became

  5. Investigation and Characterization of Defects in Epitaxial Films for Ultraviolet Light Emitting Devices Using FUV Time-Resolved Photoluminescence, Time-Resolved Cathodoluminescence, and Spatio-Time-Resolved Cathodoluminescence Excited Using Femtosecond Laser Pulses

    Science.gov (United States)

    2013-05-22

    FWHM value11 for the NBE emission of statisti- cally homogeneous AlxGa1xN according to alloy-broaden- ing model .17 The dashed line in Fig. 4(b...broadening model (Refs. 11 and 17) is shown by dashed curve. The dashed line in (b) connects the S values for high quality GaN and AlN (Refs. 4, 10 and 12...4188 (1996); S. F. Chichibu, A. C. Abare, M. P. Mack, M. S. Minsky , T. Deguchi, D. Cohen, P. Kozodoy, S. B. Fleischer, S. Keller, J. S. Speck, J. E

  6. Characterization of Local Carrier Dynamics in AlN and AlGaN Films using High Spatial- and Time-resolution Cathodoluminescence Spectroscopy

    Science.gov (United States)

    2012-10-12

    Appl. Phys. Lett. 69, 4188 (1996); S. F. Chichibu, A. C. Abare, M. P. Mack, M. S. Minsky , T. Deguchi, D. Cohen, P. Kozodoy, S. B. Fleischer, S. Keller...x (c) 0.44 0.45 0.46 0.47 S 0 50 100 150 FW HM (m eV ) alloy broadening model (b) (a) A4 A1 After Ref. 16 much remarkable than A1, reflecting...NBE emis- sion of statistically homogeneous AlxGa1-xN according to alloy-broadening model [36]. The dashed line in Fig. 9(b) connects the Sfree

  7. Une approche du vieillissement électrique des isolants polymères par mesure d'électroluminescence et de cathodoluminescence

    OpenAIRE

    Qiao, Bo

    2015-01-01

    Electroluminescence (EL) of insulating polymers is a subject of great interest because it is associated with electrical ageing and could provide the signature of excited species under electric field. Electrical ageing and breakdown in insulating polymers is of fundamental interest to the researchers, the design engineers, the manufacturers and the customers of electrical apparatus. In this respect, Partial Discharge (PD) is a harmful process leading to ageing and failure of insulating polymer...

  8. Kinetic characteristics of the luminescence decay for industrial yttrium-gadolinium-aluminium garnet based phosphors

    OpenAIRE

    Lisitsyn, Viktor Mikhailovich; Stepanov, Sergey Aleksandrovich; Valiev, Damir Talgatovich; Vishnyakova, E. A.; Abdullin, H. A.; Marhabaeva, A. A.; Tulegenova, A. T.

    2016-01-01

    The spectral and decay kinetic characteristics of pulse cathodoluminescence and photoluminescence of phosphors based on yttrium-gadolinium-aluminum garnet were investigated using pulsed optical time resolved spectroscopy.

  9. 高性能阴极荧光分析系统及其在氮化物半导体材料中的应用%High performance cathodoluminescence and it's application in optical property investigation of the nitride semiconductors

    Institute of Scientific and Technical Information of China (English)

    徐军; 徐科; 陈莉; 张会珍

    2005-01-01

    本文介绍了一套高性能的阴极荧光(Cathodolumineseence简称CL)分析系统,该系统由一台场发射扫描电镜(FEI公司的Quatan 200F)和高性能阴极荧光谱仪(Catan公司的Mono Cl3+和液氮冷台)组成。由于使用了场发射环境扫描电镜,不仅能获得高空间分辨的形象像,而且对观察试样无需进行任何预处理(包括绝缘样品甚至含水样品),这无疑为真实的显微分析提供了强有力的手段。

  10. Compositional Zoning and Mn-Cr Systematics in Carbonates from the Y791198 CM2 Carbonaceous Chondrite

    Science.gov (United States)

    Brearley, Adrian J.; Hutcheon, Ian D.; Browning, Lauren

    2001-01-01

    Cathodoluminescence and microprobe analyses show that carbonates in Y791198 exhibit complex zoning. Cr-Mn dating suggests formation of carbonates 10 Ma after CAI formation Additional information is contained in the original extended abstract..

  11. Deterministic radiative coupling between plasmonic nanoantennas and semiconducting nanowire quantum dots

    CERN Document Server

    Jeannin, Mathieu; Bellet-Amalric, Edith; Kheng, Kuntheak; Nogues, Gilles

    2016-01-01

    We report on the deterministic coupling between single semiconducting nanowire quantum dots emitting in the visible and plasmonic Au nanoantennas. Both systems are separately carefully characterized through microphotoluminescence and cathodoluminescence. A two-step realignment process using cathodoluminescence allows for electron beam lithography of Au antennas near individual nanowire quantum dots with a precision of 50 nm. A complete set of optical properties are measured before and after antenna fabrication. They evidence both an increase of the NW absorption, and an improvement of the quantum dot emission rate up to a factor two in presence of the antenna.

  12. Age intercalibration of 40Ar/39Ar sanidine and chemically distinct U/Pb zircon populations from the Alder Creek Rhyolite Quaternary geochronology standard

    DEFF Research Database (Denmark)

    Rivera, Tiffany; Storey, Michael; Schmitz, M. D.;

    2013-01-01

    (2σ external uncertainty), determined relative to the astronomically dated A1 tephra sanidine, is interpreted as the ACR eruption age. This age is supported by CA-TIMS U–Pb zircon dating, guided by LA-ICPMS trace element analyses, titanium-in-zircon (TiZR) thermometry, and cathodoluminescence (CL...

  13. Crystallization and uplift path of late Variscan granites evidenced by quartz chemistry and fluid inclusions: Example from the Land's End granite, SW England

    Science.gov (United States)

    Drivenes, Kristian; Larsen, Rune Berg; Müller, Axel; Sørensen, Bjørn Eske

    2016-05-01

    The megacrystic, coarse-grained granite of the Land's End granitic complex, SW England, has been investigated by analyzing fluid inclusions, trace elements, and cathodoluminescence textures of quartz. By applying the TitaniQ geothermobarometer together with the cathodoluminescence textures, a two-stage emplacement process is proposed. K-feldspar and quartz phenocrysts crystallized in a deep magma chamber at ca. 18-20 km depth. The phenocrysts were transported together with the melt to a shallow emplacement depth at ca. 5-9 km in multiple intrusive events, causing the composite appearance of the granitic complex. This model of emplacement concurs with similar granites from the Erzgebirge. At the emplacement level, the magma exsolved an aqueous fluid with average salinity of 17.3% m/m NaCl and 9.7% m/m CaCl2. Fluids with higher salinities were exsolved deeper in the system, as the magma experienced stages of water saturation and water undersaturation during ascent from the deep magma chamber. The complex fluid inclusion textures are the results of multiple stages of entrapment of aqueous fluids in the host phases as multiple recharge events from the deeper magma chamber supplied fresh melts and aqueous volatiles. Titanium contents in quartz are closely related to the panchromatic cathodoluminescence intensity, and the Al/Ti ratio is reflected by the 3.26 eV/2.70 eV ratio of hyperspectral cathodoluminescence.

  14. Invited Talk: Electron Microscopy of Quantum Dots for Display Applications

    OpenAIRE

    Fern, G; Silver, J.; Ireland, T; Howkins, A; Hobson, PH; Coe-Sullivan, S

    2015-01-01

    CdSe/ZnCdS core/shell Quantum dots with high quantum yield (~84%) were used in this experiment. For the first time the red filtered cathodoluminescence images are shown along with their corresponding electron energy loss spectrum map, and high angle annular dark field image of the corresponding particles is shown.

  15. Scanning electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1998-01-01

    Scanning Electron Microscopy provides a description of the physics of electron-probe formation and of electron-specimen interations The different imaging and analytical modes using secondary and backscattered electrons, electron-beam-induced currents, X-ray and Auger electrons, electron channelling effects, and cathodoluminescence are discussed to evaluate specific contrasts and to obtain quantitative information

  16. Structural and optical properties of self-catalytic GaAs:Mn nanowires grown by molecular beam epitaxy on silicon substrates

    DEFF Research Database (Denmark)

    Gas, Katarzyna; Sadowski, Janusz; Kasama, Takeshi;

    2013-01-01

    Mn-doped GaAs nanowires were grown in the self-catalytic growth mode on the oxidized Si(100) surface by molecular beam epitaxy and characterized by scanning and transmission electron microscopy, Raman scattering, photoluminescence, cathodoluminescence, and electron transport measurements...

  17. Diverse Electron-Induced Optical Emissions from Space Observatory Materials at Low Temperatures

    Science.gov (United States)

    Dennison, J.R.; Jensen, Amberly Evans; Wilson, Gregory; Dekany, Justin; Bowers, Charles W.; Meloy, Robert

    2013-01-01

    Electron irradiation experiments have investigated the diverse electron-induced optical and electrical signatures observed in ground-based tests of various space observatory materials at low temperature. Three types of light emission were observed: (i); long-duration cathodoluminescence which persisted as long as the electron beam was on (ii) short-duration (affect the performance of space-based observatories.

  18. Raman-in-SEM, a multimodal and multiscale analytical tool: performance for materials and expertise.

    Science.gov (United States)

    Wille, Guillaume; Bourrat, Xavier; Maubec, Nicolas; Lahfid, Abdeltif

    2014-12-01

    The availability of Raman spectroscopy in a powerful analytical scanning electron microscope (SEM) allows morphological, elemental, chemical, physical and electronic analysis without moving the sample between instruments. This paper documents the metrological performance of the SEMSCA commercial Raman interface operated in a low vacuum SEM. It provides multiscale and multimodal analyses as Raman/EDS, Raman/cathodoluminescence or Raman/STEM (STEM: scanning transmission electron microscopy) as well as Raman spectroscopy on nanomaterials. Since Raman spectroscopy in a SEM can be influenced by several SEM-related phenomena, this paper firstly presents a comparison of this new tool with a conventional micro-Raman spectrometer. Then, some possible artefacts are documented, which are due to the impact of electron beam-induced contamination or cathodoluminescence contribution to the Raman spectra, especially with geological samples. These effects are easily overcome by changing or adapting the Raman spectrometer and the SEM settings and methodology. The deletion of the adverse effect of cathodoluminescence is solved by using a SEM beam shutter during Raman acquisition. In contrast, this interface provides the ability to record the cathodoluminescence (CL) spectrum of a phase. In a second part, this study highlights the interest and efficiency of the coupling in characterizing micrometric phases at the same point. This multimodal approach is illustrated with various issues encountered in geosciences.

  19. Ferroan dolomite cement in Cambrian sandstones: burial history and hydrocarbon generation of the Baltic sedimentary basin

    DEFF Research Database (Denmark)

    Sliaupa, S.; Cyziene, J.; Molenaar, Nicolaas

    2008-01-01

    The conditions and timing of carbonate cementation in Cambrian sandstones of the Baltic sedimentary basin were determined by oxygen and carbon stable isotope and chemical data in combination with optical and cathodoluminescence petrographic studies. Studied samples represent a range in present...

  20. Angle-resolved catholdoluminescence imaging polarimetry

    NARCIS (Netherlands)

    Osorio, C.I.; Coenen, T.; Brenny, B.J.M.; Polman, A.; Koenderink, A.F.

    2015-01-01

    Cathodoluminescence spectroscopy (CL) allows characterizing light emission in bulk and nanostructured materials and is a key tool in fields ranging from materials science to nanophotonics. Previously, CL measurements focused on the spectral content and angular distribution of emission, while the pol

  1. Luminescence Spectroscopical Properties of Plagioclase Particles from the Hayabusa Sample Return Mission: An Implication for Study of Space Weathering Processes in the Asteroid Itokawa.

    Science.gov (United States)

    Gucsik, Arnold; Nakamura, Tomoki; Jäger, Cornelia; Ninagawa, Kiyotaka; Nishido, Hirotsugu; Kayama, Masahiro; Tsuchiyama, Akira; Ott, Ulrich; Kereszturi, Ákos

    2017-02-01

    We report a systematic spectroscopical investigation of three plagioclase particles (RB-QD04-0022, RA-QD02-0025-01, and RA-QD02-0025-02) returned by the Hayabusa spacecraft from the asteroid Itokawa, by means of scanning electron microscopy, cathodoluminescence microscopy/spectroscopy, and micro-Raman spectroscopy. The cathodoluminescence properties are used to evaluate the crystallization effects and the degree of space weathering processes, especially the shock-wave history of Itokawa. They provide new insights regarding spectral changes of asteroidal bodies due to space weathering processes. The cathodoluminescence spectra of the plagioclase particles from Itokawa show a defect-related broad band centered at around 450 nm, with a shoulder peak at 425 nm in the blue region, but there are no Mn- or Fe-related emission peaks. The absence of these crystal field-related activators indicates that the plagioclase was formed during thermal metamorphism at subsolidus temperature and extreme low oxygen fugacity. Luminescence characteristics of the selected samples do not show any signatures of the shock-induced microstructures or amorphization, indicating that these plagioclase samples suffered no (or low-shock pressure regime) shock metamorphism. Cathodoluminescence can play a key role as a powerful tool to determine mineralogy of fine-grained astromaterials.

  2. Band alignment and defects of the diamond zinc oxide heterojunction; Bandstruktur und Defekte der Diamant-Zinkoxid-Heterostruktur

    Energy Technology Data Exchange (ETDEWEB)

    Geithner, Peter

    2008-09-12

    Zinc oxide films were grown on diamond single crystals by rf sputtering of zinc oxide. The valence and conduction band offset was determined by photoelectron spectroscopy. A deep defect occurring in the zinc oxide films on diamond was characterized by cathodoluminescence spectroscopy. (orig.)

  3. Role of structural defects in the ultraviolet luminescence of multiwall boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Pierret, Aurélie; Nong, Hanond; Fossard, Frédéric; Loiseau, Annick, E-mail: annick.loiseau@onera.fr [Laboratoire d' Etude des Microstructures (LEM), ONERA-CNRS, BP 72, 92322 Châtillon cedex (France); Attal-Trétout, Brigitte [DMPH, ONERA, Chemin de la Hunière et des Joncherettes, BP 80100, 91123 Palaiseau (France); Xue, Yanming; Golberg, Dmitri [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 3050044 (Japan); Barjon, Julien, E-mail: julien.barjon@uvsq.fr [Groupe d' Etude de la Matière Condensée, University of Versailles St-Quentin and CNRS, Université Paris-Saclay, 45 Avenue des Etats-Unis, 78000 Versailles (France)

    2015-12-21

    BN nanotubes (BNNTs) are structurally similar to their carbon counterparts, though much less investigated. New synthesis methods have been recently reported, enabling the production of industrial quantities and stimulating the search of new applications for the BNNTs. In this paper, we investigate the luminescence of multiwall BNNTs. By performing cathodoluminescence experiments on single tubes at 10 K, we show that the tube luminescence is highly heterogeneous (i) from tube to tube and (ii) spatially along a single tube. By combining cathodoluminescence measurements with a nanometer excitation and transmission electron microscopy on the same tube, we correlate luminescence and structural features. We conclude that the near-band-edge luminescence of BNNTs (≈5.4 eV) is related to the presence of extended structural defects, such as dislocations or ruptures in the wall stacking.

  4. Role of structural defects in the ultraviolet luminescence of multiwall boron nitride nanotubes

    Science.gov (United States)

    Pierret, Aurélie; Nong, Hanond; Fossard, Frédéric; Attal-Trétout, Brigitte; Xue, Yanming; Golberg, Dmitri; Barjon, Julien; Loiseau, Annick

    2015-12-01

    BN nanotubes (BNNTs) are structurally similar to their carbon counterparts, though much less investigated. New synthesis methods have been recently reported, enabling the production of industrial quantities and stimulating the search of new applications for the BNNTs. In this paper, we investigate the luminescence of multiwall BNNTs. By performing cathodoluminescence experiments on single tubes at 10 K, we show that the tube luminescence is highly heterogeneous (i) from tube to tube and (ii) spatially along a single tube. By combining cathodoluminescence measurements with a nanometer excitation and transmission electron microscopy on the same tube, we correlate luminescence and structural features. We conclude that the near-band-edge luminescence of BNNTs (≈5.4 eV) is related to the presence of extended structural defects, such as dislocations or ruptures in the wall stacking.

  5. Electronic fine structure and recombination dynamics in single InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Seguin, R.

    2008-01-28

    In the work at hand single InAs/GaAs quantum dots (QDs) are examined via cathodoluminescence spectroscopy. A thorough analysis of the spectra leads to an unambiguous assignment of the lines to the decay of specific excitonic complexes. A special aspect of the Coulomb interaction, the exchange interaction, gives rise to a fine structure in the initial and final states of an excitonic decay. This leads to a fine structure in the emission spectra that again is unique for every excitonic complex. The exchange interaction is discussed in great detail in this work.QDs of different sizes are investigated and the influence on the electronic properties is monitored. Additionally, the structure is modified ex situ by a thermal annealing process. The changes of the spectra under different annealing temperatures are traced. Finally, recombination dynamics of different excitonic complexes are examined by performing time-resolved cathodoluminescence spectroscopy. (orig.)

  6. Characterization of Er{sub 2}O{sub 3} ceramic coatings by luminescence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, T., E-mail: teru@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Yoshino, M. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Hishinuma, Y. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Zhang, D. [School of Physical Sciences, The Graduate University for Advanced Studies, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Kada, W. [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki-shi, Gunma 370-1292 (Japan); Sato, F.; Iida, T. [Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Nagasaki, T. [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Muroga, T. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan)

    2011-10-01

    Cathodoluminescence and ion beam induced luminescence measurements were performed on Er{sub 2}O{sub 3} coatings fabricated by the Metal Organic Chemical Vapor Deposition (MOCVD), Metal Organic Decomposition (MOD) and RF sputtering methods to examine relations between luminescence spectra and their crystallinities. In luminescence spectra of all the measurements, peaks were observed in three bands of 380-420 nm, 530-580 nm and 640-690 nm. Cathodoluminescence intensities in the band of 640-690 nm increased with substrate temperatures in the fabrication processes and are considered to be significantly sensitive to the crystallinity. Change in luminescence spectra under ion beam irradiations also supported the relation. By using the relations between the spectra and crystallinities, luminescence measurements would be effective for nondestructive inspection and analysis of Er{sub 2}O{sub 3} coatings with a high spatial resolution.

  7. Optical quality improvement of MOVPE grown GaAlAs/GaAs double heterostructures on silicon substrates

    Science.gov (United States)

    Draïdia, N.; Azoulay, R.; Dugrand, L.; Papadopoulo, A. C.; Gao, Y.; Sermage, B.; Ossart, P.; Meddeb, J.

    1991-01-01

    We report a study of metalorganic vapour phase epitaxy (MOVPE) grown GaAlAs/GaAs double heterostructures on Si substrates. The main part of this work deals with the influence of post growth annealing conditions on cathodoluminescence (CL) efficiency, defect reduction, Si distribution over the structure, and interfaces state. It has been found by 300 K cathodoluminescence measurements that treatment at high temperature up to 900°C reduces defect and deep level transitions giving rise to larger zones of high near band edge (NBE) emission luminescence in contrast to those observed on unannealed samples. Such improvement has been confirmed by transmission electron microscopy and luminescence decay measurements. Carrier life times as 6 ns have been measured indicating a ten fold increase after annealing.

  8. Optical quality improvement of MOVPE grown GaAlAs/GaAs double heterostructures on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Draidia, N.; Azoulay, R.; Dugrand, L.; Papadopoulo, A.C.; Gao, Y.; Sermage, B.; Ossart, P. (Centre National des Etudes des Telecommunications, Lab. de Bagneux, 92 (France)); Meddeb, J. (Dept. de Physique de la Matiere, Univ. Claude Bernard, 69 - Villeurbanne (France))

    1991-01-01

    We report a study of metalorganic vapour phase epitaxy (MOVPE) grown GaAlAs/GaAs double heterostructures on Si substrates. The main part of this work deals with the influence of post growth annealing conditions on cathodoluminescence (CL) efficiency, defect reduction, Si distribution over the structure, and interfaces state. It has been found by 300 K cathodoluminescence measurements that treatment at high temperature up to 900degC reduces defect and deep level transitions giving rise to larger zones of high near band edge (NBE) emission luminescence in contrast to those observed on unannealed samples. Such improvement has been confirmed by transmission electron microscopy and luminescence decay measurements. Carrier life times as large as 6 ns have been measured indicating a ten fold increase after annealing. (orig.).

  9. Color centers in diamond: versatile and powerful tools for bioimaging

    Science.gov (United States)

    Zhang, Huiliang; Glenn, David; Trifonov, Alexei; Pham, My; Le Sage, David; Kasthuri, Narayanan; Schalek, Richard; Lichtman, Jeff; Walsworth, Ronald; Walsworth Group Collaboration; Lichtman Lab Collaboration

    2011-05-01

    We present recent progress in the application of nitrogen vacancy (NV) and other color centers in diamond to demanding bioimaging applications, including: (i) nanodiamond cathodoluminescence (CL) to provide molecular-function correlated color to electron microscopy of the connections between neurons (``Connectomics'') (ii) super-resolution optical imaging of functionalized nanodiamonds in brain tissue using variants of STED, GSD or STORM techniques; and (iii) magnetic field sensing and imaging of neural activities using an NV- diamond magnetometer.

  10. Scanning electron microscopy of lunar regolith from the Sea of Fertility

    Science.gov (United States)

    Antoshin, M. K.; Ilin, N. P.; Spivak, G. V.

    1974-01-01

    Scanning electron microscopy was used in studying the morphology and cathodoluminescence of lunar regolith particles. Surface and structure of two groups of particles are differentiated: (1) Crystalline with well defined facets and spalling surfaces, which are grains of minerals and rock fragments: and (2) amorphous, fused, and partially or entirely glazed particles. Local melting of particles and the round openings on their surfaces are attributed to secondary influence on the regolith of factors of lunar weathering and above all micrometeoric impacts.

  11. Status of Structural Analysis of Substrates and Film Growth Inputs for GaN Device Development Program

    Science.gov (United States)

    2011-01-01

    from 8 scans per 2” sample to 32. Our team has been developing GaN Schottky diodes and HEMTs with segments of these wafers. 12 Figure 7. Ranking...analysis of variance Asym asymmetric x-ray scan CL cathodoluminescence FOM figure of merit FWHM full width at half maximum GaN gallium nitride HEMT ...Status of Structural Analysis of Substrates and Film Growth Inputs for GaN Device Development Program by Kevin Kirchner ARL-TR-5427

  12. Three-dimensional mapping of quantum wells in a GaN/InGaN core-shell nanowire light-emitting diode array.

    Science.gov (United States)

    Riley, James R; Padalkar, Sonal; Li, Qiming; Lu, Ping; Koleske, Daniel D; Wierer, Jonathan J; Wang, George T; Lauhon, Lincoln J

    2013-09-11

    Correlated atom probe tomography, cross-sectional scanning transmission electron microscopy, and cathodoluminescence spectroscopy are used to analyze InGaN/GaN multiquantum wells (QWs) in nanowire array light-emitting diodes (LEDs). Tomographic analysis of the In distribution, interface morphology, and dopant clustering reveals material quality comparable to that of planar LED QWs. The position-dependent CL emission wavelength of the nonpolar side-facet QWs and semipolar top QWs is correlated with In composition.

  13. Structure, chemistry and luminescence properties of dielectric La{sub x}Hf{sub 1-x}O{sub y} films

    Energy Technology Data Exchange (ETDEWEB)

    Kaichev, V.V., E-mail: vvk@catalysis.ru [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Smirnova, T.P.; Yakovkina, L.V. [Nikolaev Institute of Inorganic Chemistry, Novosibirsk (Russian Federation); Ivanova, E.V.; Zamoryanskaya, M.V. [Ioffe Physical-Technical Institute, St. Petersburg (Russian Federation); Saraev, A.A. [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Pustovarov, V.A. [Ural State Technical University, Ekaterinburg (Russian Federation); Perevalov, T.V.; Gritsenko, V.A. [Novosibirsk State University, Novosibirsk (Russian Federation); Rzhanov Institute of Semiconductor Physics, Novosibirsk (Russian Federation)

    2016-06-01

    Dielectric films of La{sub 2}O{sub 3}, HfO{sub 2}, and La{sub x}Hf{sub 1-x}O{sub y} were synthesized by metal-organic chemical vapor deposition. Structural, chemical, and luminescence properties of the films were studied using X-ray photoelectron spectroscopy, methods of X-ray diffraction and selected area electron diffraction, high-resolution transmission electron microscopy, and a cathodoluminescence technique. It was found that doping of hafnium oxide with lanthanum leads to the formation of a continuous series of solid solutions with a cubic structure. This process is accompanied by the formation of oxygen vacancies in the HfO{sub 2} lattice. Cathodoluminescence spectra of the La{sub x}Hf{sub 1-x}O{sub y}/Si films exhibited a wide band with the maximum near 2.4–2.5 eV, which corresponds to the blue emission. Quantum-chemical calculations showed that this blue band is due to oxygen vacancies in the HfO{sub 2} lattice. - Highlights: • HfO{sub 2} and solid solution La{sub x}Hf{sub 1-x}O{sub y} films were synthesized by MOCVD. • The continuous series of solid solutions with a cubic structure was formed at La doping of HfO{sub 2}. • Cathodoluminescence band at 2.4–2.5 eV is observed due to the oxygen vacancies in La{sub x}Hf{sub 1-x}O{sub y}. • The cathodoluminescence decreases in intensity when the La concentration increases.

  14. Near-Field Plasmonic Behavior of Au/Pd Nanocrystals with Pd-Rich Tips

    CERN Document Server

    Ringe, Emilie; Collins, Sean M; Duchamp, Martial; Dunin-Borkowski, Rafal E; Skrabalak, Sara E; Midgley, Paul A

    2015-01-01

    Using nanometer spatial resolution electron-energy loss spectroscopy (EELS), energy dispersive X-ray spectroscopy (EDS), and cathodoluminescence (CL) mapping, we demonstrate that Au alloys containing a poor plasmonic metal (Pd) can nevertheless sustain multiple size-dependent localized surface plasmon resonances and observe strong field enhancement at Pd-rich tips, where the composition is in fact least favorable for plasmons. These Au/Pd stellated nanocrystals are also involved in substrate and interparticle coupling, as unraveled by EELS tilt series.

  15. Electron Irradiation Effects on Nanocrystal Quantum Dots Used in Bio-Sensing Applications

    Science.gov (United States)

    Leon, R.; Nadeau, J.; Evans, K.; Paskova, T.; Monemar, B.

    2004-01-01

    Effects of electron irradiation on some of the optical properties in organic CdSe nanocrystals coated in trioctylphosphine oxide (TOPO) and biologically compatible CdSe nanocrystals coated in mercaptoacetic acid, as CdSe as CdSe nanocrystals conjugated with the protein are investigated using the technique of cathodoluminescence. Effects of varying the beam energy and temperatures were examined and faster degradation at cryogenic temperatures and higher beam energies was found under some conditions.

  16. Zircon U-Pb SHRIMP ages of high-pressure granulite in Yushugou ophiolitic terrane in southern Tianshan and their tectonic implications

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dingwu; SU Li; JIAN Ping; WANG Runsan; LIU Xiaoming; LU Guanxiang; WANG Juli

    2004-01-01

    Zircons from two high-pressure granulite samples from the Yushugou ophiolitic terrane, southern Tianshan have been investigated by cathodoluminescence, LAICPMS and ion microprobe (SHRIMP) for their internal textures, trace elemental compositions and in situ dating. The weighted mean ages of these two samples are 392±7 and 390±11 Ma, respectively, representing the granulite-facies metamorphic age of the ophiolitic terrane, and indicating that the southern Tianshan ocean initiated its northward subduction since the early Devonian.

  17. Luminescent characteristics of praseodymium-doped zinc aluminate powders

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Perez, C.D.; Garcia-Hipolito, M.; Alvarez-Fregoso, O. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Coyoacan, DF (Mexico); Alvarez-Perez, M.A. [Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, Coyoacan, DF (Mexico); Ramos-Brito, F. [Laboratorio de Materiales Optoelectronicos, DIDe, Centro de Ciencias de Sinaloa, Av. De las Americas No. 2771 Nte. Col. Villa Universidad, Culiacan, Sinaloa (Mexico); Falcony, C. [Centro de Investigaciones y Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico)

    2010-02-15

    In this research, we report the cathodoluminescence (CL) and preliminary photoluminescence (PL) properties of praseodymium-doped zinc aluminate powders. ZnAl{sub 2}O{sub 4}:Pr powders were synthesized by a very simple chemical process. X-ray diffraction spectra indicated a cubic spinel crystalline structure with an average crystallite size of 15 nm. CL properties of the powders were studied as a function of the praseodymium concentration and electron-accelerating potential. In this case, all the cathodoluminescent emission spectra showed main peaks located at 494, 535, 611, 646, and 733 nm, which were associated to the electronic transitions {sup 3}P{sub 0}{yields}{sup 3}H{sub 4}, {sup 3}P{sub 0}{yields}{sup 3}H{sub 5}, {sup 3}P{sub 0}{yields}{sup 3}H{sub 6}, {sup 3}P{sub 0}{yields}{sup 3}F{sub 2}, and {sup 3}P{sub 0}{yields}{sup 3}F{sub 4} of the Pr{sup 3+} ions, respectively. A quenching of the CL, with increasing doping concentration, was observed. Also, an increment on cathodoluminescent emission intensity was observed as the accelerating voltage increased. The PL emission spectrum showed similar characteristics to those of the CL spectra. The chemical composition of the powders, as determined by energy dispersive spectroscopy, is also reported. In addition, the surface morphology characteristics of the powders are shown. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Luminescence and tenebrescence of natural sodalites: a chemical and structural study

    Science.gov (United States)

    Zahoransky, Teresa; Friis, Henrik; Marks, Michael A. W.

    2016-07-01

    Sodalite (Na8Al6Si6O24Cl2) shows a wide range of colours and may exhibit a variety of optical properties including cathodoluminescence, photoluminescence and tenebrescence. These optical peculiarities are not yet fully understood but are of key interest for industry. We provide a detailed study on the photochromic properties of natural sodalite, and we show that S is crucially influencing luminescence of sodalites. A reduced intensity in cathodoluminescence was observed at high S contents for some samples, showing that S can act as cathodoluminescence quencher. Photoluminescent sodalites are generally enriched in S compared to non-photoluminescent samples, although few samples being very low in S still show photoluminescence. Additionally, S was found to enlarge the unit cell in natural sodalites which might have a crucial impact on their photochromic properties. The most efficient tenebrescent samples were found to be low in Fe, Mn and S. They showed the smallest unit-cell dimensions, and a strong link between the atomic structure and the formation of F-centres is proposed. Tenebrescence in natural sodalites appears to be enhanced (1) by S but saturated at too high S concentrations and (2) by a stoichiometry and structure close to the ideal sodalite composition. In contrast to the term self-quenching for luminescence, we propose a saturation of F-centres to explain tenebrescence at different S contents.

  19. Energy Levels of Coupled Plasmonic Cavities

    Institute of Scientific and Technical Information of China (English)

    Chuan-Pu Liu; Xin-Li Zhu; Jia-Sen Zhang; Jun Xu; Yamin Leprince-Wang; Da-Peng Yu

    2016-01-01

    We demonstrate the hybridization of the plasmonic modes in directly coupled whispering gallery cavities fabricated on silver films and present the mode patterns and energy levels using cathodoluminescence spectroscopy.Although the energy of the most antisymmetrically coupled modes is higher than that of the corresponding symmetrically coupled ones,the contrary cases happen for small quantum number modes.We attribute the phenomenon to the different surface plasmon polariton paths between the symmetrically and antisymmetrically coupled modes.These results provide an understanding of the resonant properties in coupled plasmonic cavities,which have potential applications in nanophotonic devices.

  20. Design of titania nanotube structures by focused laser beam direct writing

    Energy Technology Data Exchange (ETDEWEB)

    Enachi, Mihai [National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, Chisinau, MD-2004 (Moldova, Republic of); Stevens-Kalceff, Marion A. [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Sarua, Andrei [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Ursaki, Veaceslav [Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, MD-2028 (Moldova, Republic of); Tiginyanu, Ion, E-mail: tiginyanu@asm.md [National Center for Materials Study and Testing, Technical University of Moldova, Stefan cel Mare av. 168, Chisinau, MD-2004 (Moldova, Republic of); Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Chisinau, MD-2028 (Moldova, Republic of)

    2013-12-21

    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO{sub 2} NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes.

  1. Adherence Characteristics of Cement Clinker on Basic Bricks

    Institute of Scientific and Technical Information of China (English)

    GUO Zongqi; Michel Rigaud

    2002-01-01

    Based on the sandwich test, adherence mechanisms of cement clinker on various basic bricks were tackled by microstructural observations with help of cathodoluminescence technique. Doloma based bricks offer sufficient lime to react with clinker, forming C3 S rich layer and initializing superior adherence. However, clinker with low silica ratio leads to MgO agglomeration at the interface of doloma bricks, which reduces adherence strength. On magnesia spinel bricks, fine, crystalline spinel easily reacts with lime containing phases from clinker to form lowmelting phases and belite zone, which shows high adherence performance. Lack of fine spinel in magnesia spinel bricks results in poor adherence.

  2. Direct observation of potential barrier formation at grain boundaries of SnO2 ceramics

    Science.gov (United States)

    Maestre, D.; Cremades, A.; Piqueras, J.

    2004-11-01

    Remote electron beam induced current (REBIC) and cathodoluminescence (CL) modes in the scanning electron microscope (SEM) have been used to investigate SnO2 sintered samples. The study of the electrically active boundaries present in the oxide shows a characteristic peak and trough (PAT) contrast after thermal treatments in oxygen. Temperature-dependent measurements of the REBIC contrast show the presence of a shallow defect level 60 meV below the conduction band. This level is asigned to oxygen species adsorbed on the defect-rich boundaries. Evolution of REBIC contrast of the grain boundaries with excitation density enabled us to perform local measurements of minority carrier diffusion length.

  3. Solid-phase data from cores at the proposed Dewey Burdock uranium in-situ recovery mine, near Edgemont, South Dakota

    Science.gov (United States)

    Johnson, Raymond H.; Diehl, Sharon F.; Benzel, William M.

    2013-01-01

    This report releases solid-phase data from cores at the proposed Dewey Burdock uranium in-situ recovery site near Edgemont, South Dakota. These cores were collected by Powertech Uranium Corporation, and material not used for their analyses were given to the U.S. Geological Survey for additional sampling and analyses. These additional analyses included total carbon and sulfur, whole rock acid digestion for major and trace elements, 234U/238U activity ratios, X-ray diffraction, thin sections, scanning electron microscopy analyses, and cathodoluminescence. This report provides the methods and data results from these analyses along with a short summary of observations.

  4. Luminescent properties of diamond single crystals of pyramidal shape

    Science.gov (United States)

    Alekseev, A. M.; Tuyakova, F. T.; Obraztsova, E. A.; Korostylev, E. V.; Klinov, D. V.; Prusakov, K. A.; Malykhin, S. A.; Ismagilov, R. R.; Obraztsov, A. N.

    2016-11-01

    The luminescence properties of needle-like crystals of diamond, obtained by selective oxidation of textured polycrystalline diamond films, are studied. Diamond films were grown by chemical vapor deposition from a methane-hydrogen mixture activated by a DC discharge. The spectra of photo- and cathodoluminescence and the spatial distribution of the intensity of radiation at different wavelengths are obtained for individual needle-like crystals. Based on the spectral characteristics, conclusions are made about the presence of optically active defects containing nitrogen and silicon impurities in their structure, as well as the significant effect of structural defects on their luminescence spectra.

  5. Characterization methods dedicated to nanometer-thick hBN layers

    Science.gov (United States)

    Schué, Léonard; Stenger, Ingrid; Fossard, Frédéric; Loiseau, Annick; Barjon, Julien

    2017-03-01

    Hexagonal boron nitride (hBN) has regained interest as a strategic component in graphene engineering and in van der Waals heterostructures built with two dimensional materials. It is crucial then, to handle reliable characterization techniques capable to assess the quality of structural and electronic properties of the hBN material used. We present here characterization procedures based on optical spectroscopies, namely cathodoluminescence and Raman, with the additional support of structural analysis conducted by transmission electron microscopy. We show the capability of optical spectroscopies to investigate and benchmark the optical and structural properties of various hBN thin layers sources.

  6. Note: Portable rare-earth element analyzer using pyroelectric crystal

    Energy Technology Data Exchange (ETDEWEB)

    Imashuku, Susumu, E-mail: imashuku.susumu.2m@kyoto-u.ac.jp; Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun [Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501 (Japan)

    2013-12-15

    We report a portable rare-earth element analyzer with a palm-top size chamber including the electron source of a pyroelectric crystal and the sample stage utilizing cathodoluminescence (CL) phenomenon. The portable rare-earth element analyzer utilizing CL phenomenon is the smallest reported so far. The portable rare-earth element analyzer detected the rare-earth elements Dy, Tb, Er, and Sm of ppm order in zircon, which were not detected by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. We also performed an elemental mapping of rare-earth elements by capturing a CL image using CCD camera.

  7. Transformation optics: a time- and frequency-domain analysis of electron-energy loss spectroscopy

    CERN Document Server

    Kraft, Matthias; Pendry, J B

    2016-01-01

    Electron energy loss spectroscopy (EELS) and Cathodoluminescence (CL) play a pivotal role in many of the cutting edge experiments in plasmonics. EELS and CL experiments are usually supported by numerical simulations, which, whilst accurate, may not provide as much physical insight as analytical calculations do. Fully analytical solutions to EELS and CL systems in plasmonics are rare and difficult to obtain. This paper aims to narrow this gap by introducing a new method based on Transformation optics that allows to calculate the quasi-static frequency and time-domain response of plasmonic particles under electron beam excitation.

  8. Highly transparent ammonothermal bulk GaN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, WK; Ehrentraut, D; Downey, BC; Kamber, DS; Pakalapati, RT; Do Yoo, H; D' Evelyn, MP

    2014-10-01

    A novel apparatus has been employed to grow ammonothermal (0001) gallium nitride (GaN) with diameters up to 2 in The crystals have been characterized by x-ray diffraction rocking-curve (XRC) analysis, optical and scanning electron microscopy (SEM), cathodoluminescence (CL), and optical spectroscopy. High crystallinity GaN with FWHM values about 20-50 arcsec and dislocation densities below 1 x 10(5) cm(-2) have been obtained. High optical transmission was achieved with an optical absorption coefficient below 1 cm(-1) at a wavelength of 450 nm. (C) 2014 Elsevier B.V. All rights reserved.

  9. Optical properties of self assembled GaN polarity inversion domain boundary

    Energy Technology Data Exchange (ETDEWEB)

    Liu, M.-C.; Cheng, Y.-J. [Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Chang, J.-R.; Chang, C.-Y. [Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 300, Taiwan (China); Hsu, S.-C. [Department of Chemical and Materials Engineering, Tamkang University, No.151, Yingzhuan Rd., Danshui Dist., Taipei, Taiwan (China)

    2011-07-11

    We report the fabrication of GaN lateral polarity inversion heterostructure with self assembled crystalline inversion domain boundaries (IDBs). The sample was fabricated by two step molecular-beam epitaxy (MBE) with microlithography patterning in between to define IDBs. Despite the use of circular pattern, hexagonal crystalline IDBs were self assembled from the circular pattern during the second MBE growth. Both cathodoluminescent (CL) and photoluminescent (PL) measurements show a significant enhanced emission at IDBs and in particular at hexagonal corners. The ability to fabricate self assembled crystalline IDBs and its enhanced emission property can be useful in optoelectronic applications.

  10. Long Lifetime Hole Traps at Grain Boundaries in CdTe Thin-Film Photovoltaics

    Science.gov (United States)

    Mendis, B. G.; Gachet, D.; Major, J. D.; Durose, K.

    2015-11-01

    A novel time-resolved cathodoluminescence method, where a pulsed electron beam is generated via the photoelectric effect, is used to probe individual CdTe grain boundaries. Excitons have a short lifetime (≤100 ps ) within the grains and are rapidly quenched at the grain boundary. However, a ˜47 meV shallow acceptor, believed to be due to oxygen, can act as a long lifetime hole trap, even at the grain boundaries where their concentration is higher. This provides direct evidence supporting recent observations of hopping conduction across grain boundaries in highly doped CdTe at low temperature.

  11. Light-emitting diode based on mask- and catalyst-free grown N-polar GaN nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Kunert, G; Freund, W; Aschenbrenner, T; Kruse, C; Figge, S; Hommel, D [Institute of Solid State Physics-Semiconductor Epitaxy-University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen (Germany); Schowalter, M; Rosenauer, A [Institute of Solid State Physics-Electron Microscopy-University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen (Germany); Kalden, J; Sebald, K; Gutowski, J [Institute of Solid State Physics-Semiconductor Optics-University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen (Germany); Feneberg, M; Tischer, I; Fujan, K; Thonke, K, E-mail: kunert@ifp.uni-bremen.de [Institute of Quantum Matter-Semiconductor Physics-University of Ulm, Albert-Einstein-Allee 45, 89081 Ulm (Germany)

    2011-07-01

    We report on the fabrication of a light-emitting diode based on GaN nanorods containing InGaN quantum wells. The unique system consists of tilted N-polar nanorods of high crystalline quality. Photoluminescence, electroluminescence, and spatially resolved cathodoluminescence investigations consistently show quantum well emission around 2.6 eV. Scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy measurements reveal a truncated shape of the quantum wells with In contents of (15 {+-} 5)%.

  12. Synthesis and Luminescent Properties of GaN and GaN-Mn Blue Nanocrystalline Thin-film Phosphor for FED

    Energy Technology Data Exchange (ETDEWEB)

    Bondar, V D; Felter, T E; Hunt, C E; Kucharsky, I Y; Chakhovskoi, A G

    2003-04-09

    The technologies of fabrication of thin film phosphors based on gallium nitride using rf-magnetron sputtering are developed and structural properties of films are studied. Luminescence and electron spin resonance (ESR) spectra of GaN and GaN-Mn thin films have been studied. The correlation between cathodoluminescence intensity and conductivity of GaN films has been found. The nature of emission centers in GaN and GaN-Mn thin films is discussed as well as mechanism of luminescence in these films is proposed.

  13. Lateral growth of GaN by liquid phase electroepitaxy using mesa-shaped substrate

    Science.gov (United States)

    Kambayashi, Daisuke; Takakura, Hiroyuki; Tomita, Masafumi; Iwakawa, Muneki; Mizuno, Yosuke; Maruyama, Takahiro; Naritsuka, Shigeya

    2016-10-01

    GaN microchannel epitaxy (MCE) was performed using a mesa-shaped substrate and liquid phase electroepitaxy. A flat and wide MCE layer was successfully obtained with a rectangular shape, which is formed by ±c-planes on both the top and bottom surfaces. MCE growth proceeded mainly in the lateral direction by the formation of these planes. Cathodoluminescence measurements showed that the laterally grown layers were almost free of dislocations, and that the dislocations in the mesa areas were confined by the vertical sides of the mesas. In the case of inclined sides, the dislocations would be expected to bend and spread into the laterally grown areas.

  14. Nitrogen-Doped Chemical Vapour Deposited Diamond: a New Material for Room-Temperature Solid State Maser

    Institute of Scientific and Technical Information of China (English)

    N. A. Poklonski; N. M. Lapchuk; A. V. Khomich; LU Fan-Xiu; TANG Wei-Zhong; V. G. Ralchenko; I. I. Vlasov; M. V. Chukichev; Sambuu Munkhtsetseg

    2007-01-01

    Electron spin resonance (ESR) in polycrystalline diamond films grown by dc arc-jet and microwave plasma chemical vapour deposition is studied. The films with nitrogen impurity concentration up to 8 × 1018 cm-3 are also characterized by Raman, cathodoluminescence and optical absorption spectra. The ESR signal from P1 centre with g-factor of 2.0024 (nitrogen impurity atom occupying C site in diamond lattice) is found to exhibit an inversion with increasing the microwave power in an H102 resonator. The spin inversion effect could be of interest for further consideration of N-doped diamonds as a medium for masers operated at room temperature.

  15. Investigation of polycrystalline CdTe thin films deposited by physical vapor deposition, close-spaced sublimation, and sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Hasoon, F.S.; Abulfotuh, F.; Kazmerski, L.L. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

    1995-11-01

    CdTe thin films, deposited on different substrate structures by physical vapor deposition, sputtering, and close-spaced sublimation, have been treated with CdCl{sub 2} at several temperatures. The morphology of the films has been studied by atomic force microscopy, and the observations were correlated to results obtained from x-ray diffraction, cathodoluminescence, and minority-carrier lifetime measurements. The samples treated at 400 {degree}C resulted in the best device-quality films, independent of deposition method and underlying substrate structure. For the first time, a nanograin structure was observed in CdTe sputtered samples. copyright {ital 1995} {ital American} {ital Vacuum} {ital Society}.

  16. Grain boundaries in CdTe thin film solar cells: a review

    Science.gov (United States)

    Major, Jonathan D.

    2016-09-01

    The current state of knowledge on the impact of grain boundaries in CdTe solar cells is reviewed with emphasis being placed on working cell structures. The role of the chemical composition of grain boundaries as well as growth processes are discussed, along with characterisation techniques such as electron beam induced current and cathodoluminescence, which are capable of extracting information on a level of resolution comparable to the size of the grain boundaries. Work which attempts to relate grain boundaries to device efficiency is also assessed and gaps in the current knowledge are highlighted.

  17. Research on Y2O3:Eu Phosphor Coated with In2O3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Y2O3:Eu red phosphor for FED application was prepared by high temperature solid-state reaction. The In2O3 coating by precipitation method to the phosphor was applied and the analyses of XRD, Zeta potential, SEM, EDS and low voltage cathodoluminescence (CL) were conducted for investigating the coating effect. The results showed that In2O3 coating promoted the low voltage CL of the phosphor efficiently. The promotion was possibly due to the enhancement of the surface conductivity of the phosphor grains.

  18. Luminescence behavior of turquoise [CuAl{sub 6}(PO{sub 4}){sub 4}(OH){sub 8}.4H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Crespo-Feo, E., E-mail: ecrespo@geo.ucm.e [Museo Nacional de Ciencias Naturales, CSIC, C/Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Garcia-Guinea, J. [Museo Nacional de Ciencias Naturales, CSIC, C/Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Correcher, V.; Prado-Herrero, P. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain)

    2010-03-15

    We, herein, study the thermoluminescence (TL) and cathodoluminescence (CL-SEM) emissions of a commercial turquoise to determine its possible use as an emergency dosimeter. CL spectrum of bulk sample displays an intense broad emission from {approx}260 to {approx}650 nm together with a weaker narrow band at {approx}710 nm. Through EDS and EMPA chemical analyses, an important amount of rare earth elements (REE) such as Ce, La, Y, Nd, Dy, Yb, Er, Pr, Sm, Gd, Ho, Tb, and Tm have been identified associated with phosphate phases as well as in turquoise itself. Apatite [Ca{sub 5}[OH(PO{sub 4}){sub 3}

  19. Improved interface quality and luminescence capability of InGaN/GaN quantum wells with Mg pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhengyuan; Shen, Xiyang; Xiong, Huan; Li, Qingfei; Kang, Junyong; Fang, Zhilai [Xiamen University, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen (China); Lin, Feng; Yang, Bilan; Lin, Shilin [San' an Optoelectronics Co., Ltd, Xiamen (China); Shen, Wenzhong [Shanghai Jiao Tong University, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai (China); Zhang, Tong-Yi [Shanghai University, Shanghai University Materials Genome Institute and Shanghai Materials Genome Institute, Shanghai (China)

    2016-02-15

    Interface modification of high indium content InGaN/GaN quantum wells was carried out by Mg pretreatment of the GaN barrier surface. The indium in the Mg-pretreated InGaN layer was homogeneously distributed, making the interfaces abrupt. The improved interface quality greatly enhanced light emission capacity. The cathodoluminescence intensity of the Mg-pretreated InGaN/GaN quantum wells was correspondingly much stronger than those of the InGaN/GaN quantum wells without Mg pretreatment. (orig.)

  20. Characterization and growth of epitaxial layers of Gs exhibiting high resistivity for ionic implantation

    Science.gov (United States)

    1979-01-01

    Either classical or low temperature epitaxial growth techniques can be used to control the deposition of buffer layers of GaAs on semiconducting substrates and to obtain the resistivity and purity desired. Techniques developed to study, as a function of thickness, the evolution of mobilities by photoHall, and the spectroscopy of shallow and deep centers by cathodoluminescence and current transients reveal one very pure layer of medium resistivity and high mobility, and another "dead layer" of elevated resistivity far from the surface. The highly resistive layer remains pure over several microns, which appears interesting for implantation.

  1. Local study of the energy spectrum of electrons in CdSe/ZnSe QD structure by current DLTS cooperated with AFM

    Energy Technology Data Exchange (ETDEWEB)

    Litvinov, Vladimir; Sadofyev, Yuri; Rybin, Nikolay [Ryazan State Radioengineering University, Gagarin str. 59/1, 390005 Ryazan (Russian Federation); Kozlovsky, Vladimir [P. N. Lebedev Physical Institute RAS, Leninsky pr. 53, 119991 Moscow (Russian Federation)

    2012-08-15

    CdSe/ZnSe QD structure was investigated by current deep level transient spectroscopy (DLTS) with Laplace transform cooperated with atomic force microscopy (AFM). Cathodoluminescence (CL) measurements were carried out too. Basing on Laplace current DLTS with AFM and CL data an activation energy of electron emission from the quantized levels in a small group of CdSe QDs was measured. We have demonstrated the advanced capabilities of the new method of studying the electrical properties of nano-objects. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Effect of annealing on proton irradiated AlGaN/GaN based micro-Hall sensors

    Energy Technology Data Exchange (ETDEWEB)

    Abderrahmane, A.; Takahashi, H.; Tashiro, T. [Dept. of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan); Ko, P. J.; Okada, H.; Sandhu, A. [Dept. of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan and Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi Universit (Japan); Sato, S.; Ohshima, T. [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-cho, Takasaki, Gunma 370-1292 (Japan)

    2014-02-20

    The effect of annealing at 673 K on irradiated micro-Hall sensors irradiated with protons at 380keV and fluences of 10{sup 14}, 10{sup 15} and 10{sup 16} protons/cm{sup 2} is reported. Cathodoluminescence measurements were carried out at room temperature before and after annealing and showed improvement in the band edge band emission of the GaN layer. After annealing a sensor irradiated by 10{sup 15} protons/cm{sup 2} the device became operational with improvements in its magnetic sensitivity. All irradiated sensors showed improvement in their electrical characteristics after annealing.

  3. Spatially resolved luminescence spectroscopy of single GaN/(Al,Ga)N quantum disks

    Energy Technology Data Exchange (ETDEWEB)

    Jahn, U.; Trampert, A. [Paul-Drude-Institut fuer Festkoerperelektronik, Berlin (Germany); Calleja, E.; Ristic, J.; Rivera, C. [ISOM, Departamento de Ingenieria Electronica, Universidad Politecnica de Madrid, Madrid (Spain)

    2008-07-01

    The dependence of the optical transition energy E{sub t} of GaN quantum disks (Qdisks) embedded within (Al,Ga)N nanocolumns grown on a (111) Si substrate on disk thickness, disk diameter, barrier thickness, and barrier composition has been investigated by both spatially resolved cathodoluminescence spectroscopy and applying a theoretical model. Results of E{sub t} on the disk and barrier thickness, as well as barrier composition resemble those of corresponding quantum wells, whereas results on the disk diameter are essentially determined by the lateral strain distribution of the Qdisks. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Optical and electrical properties of InP/InGaAs grown selectively on SiO2-masked InP

    Science.gov (United States)

    Wang, Y. L.; Feygenson, A.; Hamm, R. A.; Ritter, D.; Weiner, J. S.; Temkin, H.; Panish, M. B.

    1991-07-01

    Heterostructures of InGaAs/InP have been grown selectively through windows in SiO2-masked InP substrates using metalorganic molecular beam epitaxy. The structures show high cathodoluminescence efficiency for window sizes down to 5 μm. A significant red shift, consistent with compressive lattice strain, and reduced intensity are observed for smaller features. Anomalous growth is observed near the edges of the windows. Selectively grown InGaAs/InP p-n junctions and bipolar transistors exhibit excellent electrical characteristics after removal of 1-2 μm of edge material.

  5. Spectroscopic Evidence for Exceptional Thermal Contribution to Electron-Beam Induced Fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, Marissa A.; Haynor, Ben; Aloni, Shaul; Ogletree, D. Frank; Wong, H.-S. Philip; Urban, Jeffrey J.; Milliron, Delia J.

    2010-11-16

    While electron beam induced fragmentation (EBIF) has been reported to result in the formation of nanocrystals of various compositions, the physical forces driving this phenomenon are still poorly understood. We report EBIF to be a much more general phenomenon than previously appreciated, operative across a wide variety of metals, semiconductors and insulators. In addition, we leverage the temperature dependent bandgap of several semiconductors to quantify -- using in situ cathodoluminescence spectroscopy -- the thermal contribution to EBIF, and find extreme temperature rises upwards of 1000K.

  6. Growth and optical investigations of high quality individual CdTe/(Cd,Mg)Te core/shell nanowires

    Science.gov (United States)

    Wojnar, P.; Płachta, J.; Kret, S.; Kaleta, A.; Zaleszczyk, W.; Szymura, M.; Wiater, M.; Baczewski, L. T.; Pietruczik, A.; Karczewski, G.; Wojtowicz, T.; Kossut, J.

    2017-01-01

    CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.

  7. Controlling the visible luminescence in hydrothermal ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Lem, Laurent L.C.; Phillips, Matthew R.; Ton-That, Cuong, E-mail: Cuong.Ton-That@uts.edu.au

    2014-10-15

    Cathodoluminescence spectra have been measured in hydrothermal and hydrogen-doped ZnO at different excitation densities and temperatures to investigate the emission efficiencies of near-band-edge (NBE), green and yellow luminescence bands. The NBE intensity depends linearly on the electron beam excitation as expected for excitonic recombination character. The intensities of the green and yellow bands are highly dependent not only on the excitation density but also on temperature. At high excitation densities ZnO exhibits dominant green emission at room temperature; the intensity of the green band can be further controlled by doping ZnO with hydrogen, which passivates green luminescence centers. Conversely at small excitation densities (< 0.1 nA) and low temperatures the visible luminescence from ZnO is predominantly yellow due to the abundance of Li in hydrothermal ZnO. The results are explained by differences in the recombination kinetics and the relative concentrations of the green and yellow centers, and illustrate that single-color emission can be achieved in ZnO by adjusting the excitation power and temperature. - Highlights: • Hydrothermal ZnO crystals are analyzed by cathodoluminescence spectroscopy. • Intensities of luminescence bands are highly dependent on excitation density. • Visible luminescence is influenced by temperature and hydrogen dopants. • Emission efficiencies are explained by recombination kinetics of defects.

  8. Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells.

    Science.gov (United States)

    Moreno-Azanza, Miguel; Bauluz, Blanca; Canudo, José Ignacio; Gasca, José Manuel; Torcida Fernández-Baldor, Fidel

    2016-01-01

    Abnormalities in the histo- and ultrastructure of the amniote eggshell are often related to diverse factors, such as ambient stress during egg formation, pathologies altering the physiology of the egg-laying females, or evolutionarily selected modifications of the eggshell structure that vary the physical properties of the egg, for example increasing its strength so as to avoid fracture during incubation. When dealing with fossil materials, all the above hypotheses are plausible, but a detailed taphonomical study has to be performed to rule out the possibility that secondary processes of recrystallization have occurred during fossilization. Traditional analyses, such as optical microscopy inspection and cathodoluminescence, have proven not to be enough to understand the taphonomic story of some eggshells. Recently, electron backscatter diffraction has been used, in combination with other techniques, to better understand the alteration of fossil eggshells. Here we present a combined study using scanning electron microscopy, optical microscopy, cathodoluminescence and electron backscatter diffraction of eggshell fragments assigned to Megaloolithus cf. siruguei from the Upper Cretaceous outcrops of the Cameros Basin. We focus our study on the presence of secondary shell units that mimic most aspects of the ultrastructure of the eggshell mammillae, but grow far from the inner surface of the eggshell. We call these structures extra-spherulites, describe their crystal structure and demonstrate their secondary origin. Our study has important implications for the interpretation of secondary shell units as biological or pathological structures. Thus, electron backscatter diffraction complements other microscope techniques as a useful tool for understanding taphonomical alterations in fossil eggshells.

  9. Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Gonzalez, M.A.; Garcia-Guinea, J. [National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Laborda, F. [Group of Analytical Spectroscopy and Sensors Group, Institute of Environmental Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Garrido, F., E-mail: fernando.garrido@mncn.csic.es [National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid (Spain)

    2015-12-01

    Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system. - Highlights: • Abandoned mine residues are Tl sources in soils of Madrid catchment area. • Tl was associated to quartz and aluminosilicates in both rocks and soils. • Tl was frequently found associated to organic particles and diatom frustules. • Cathodoluminescence is a suitable technique for Tl detection on soils and rocks.

  10. A facile method for the preparation of Eu{sup 2+}-doped nanocrystalline BaFCl

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianglei; Liu, Zhiqiang [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, UNSW Canberra (ADFA), Canberra, ACT 2600 (Australia); Stevens-Kalceff, Marion A. [School of Physics and Electron Microscope Unit, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052 (Australia); Riesen, Hans, E-mail: h.riesen@adfa.edu.au [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, UNSW Canberra (ADFA), Canberra, ACT 2600 (Australia)

    2013-10-15

    Graphical abstract: - Highlights: • A facile co-precipitation method for the preparation of Eu{sup 2+}-doped BaFCl. • Reduction of Eu{sup 3+} to Eu{sup 2+} by zinc granular under nitrogen flow. • Photoluminescence and cathodoluminescence spectroscopy of the as-prepared BaFCl:Eu{sup 2+}. • Temperature dependent photoluminescence properties of Eu{sup 2+} ions in BaFCl. - Abstract: A facile method for the preparation of Eu{sup 2+}-doped BaFCl is reported. The method is based on the co-precipitation of aqueous solutions of BaCl{sub 2} and NH{sub 4}F to yield BaFCl. The doping by europium in the 2+ oxidation state is realized by the reduction of Eu{sup 3+} to Eu{sup 2+} employing granular zinc in the BaCl{sub 2} solution under nitrogen. Powder X-ray diffraction and electron microscopy have been used to confirm the BaFCl phase and photoluminescence, in the temperature range of 2.5–290 K, and room-temperature cathodoluminescence spectra have been measured to characterize the Eu{sup 2+} ions in the sample.

  11. Evaluation of Crack-tip Stress in Titanium Oxide Film Using Piezo-spectroscopy Methods

    Institute of Scientific and Technical Information of China (English)

    WAN Keshu; ZHU Wenliang; PEZZOTTI Giuseppe; MIAO Lei; TANEMURA Sakae

    2004-01-01

    The biaxial piezo-spectroscopic coefficient of 530 nm cathodoluminescence band of polycrystalline anatase titanium oxide film was measured using a local calibration procedure. Firstly, the crack-tip stress intensity factor in titanium oxide was measured from the crack opening displacement of a Vickers indentation crack using both Irwin's formula and Fett's formula, and the validity of these two formulas was evaluated. The obtained value was about Ktip =1 MPa √m. In such a brittle material, the fracture toughness can be considered to be very close to the stress intensity factor measured in an equilibrium indentation crack (Ktip= Kc). From the Ktip value, we calculated the stress distribution ahead of the crack tip using principles of linear elastic fracture mechanics. An important finding was that the cathodoluminescence 530 nm band that originated from excitons self-trapped on TiO6 octahedra, is sensitive to stress. Using the shift of this peak and the calculated stress from linear elastic fracture mechanics, the biaxial piezo-spectroscopic coefficient of this band was determined (40 nm/GPa with a 20% error rate). Using this piezo-spectroscopic coefficient, approximate stress maps can be collected of unknown stress fields within thin films with high spatial resolution into the scanning electron microscope. The present experiments provide a vivid example of quantitative micromechanical stress analysis by piezo-spectroscopic techniques.

  12. Deep-Subwavelength Spatial Characterization of Angular Emission from Single-Crystal Au Plasmonic Ridge Nanoantennas

    CERN Document Server

    Coenen, Toon; Polman, Albert; 10.1021/nn204750d

    2013-01-01

    We use spatially and angle-resolved cathodoluminescence imaging spectroscopy to study, with deep subwavelength resolution, the radiation mechanism of single plasmonic ridge antennas with lengths ranging from 100 to 2000 nm. We measure the antenna's standing wave resonances up to the fifth order and measure the dispersion of the strongly confined guided plasmon mode. By directly detecting the emitted antenna radiation with a 2D CCD camera we are able to measure the angular emission patterns associated with each individual antenna resonance. We demonstrate that the shortest ridges can be modeled as a single point dipole emitter oriented either upward (m=0) or in-plane (m=1). The far-field emission pattern for longer antennas (m>2) is well described by two interfering in-plane point dipoles at the end facets giving rise to an angular fringe pattern, where the number of fringes increases as the antenna becomes longer. Taking advantage of the deep subwavelength excitation resolution of the cathodoluminescence tech...

  13. Optical characterization of nanopillar black silicon for plasmonic and Solar cell application

    Science.gov (United States)

    Gartia, M. R.; Chen, Y.; Xu, Z.; Bordain, Y. C.; Eichorst, J.; Mabon, J. C.; Soares, J. A. N. de T.; Clegg, R. M.; Liu, G. L.

    2011-10-01

    With the goal of improving photo-absorption of photovoltaic device and for plasmonic application we have fabricated nanopillar black silicon devices through etching-passivation technique which does not require any photomask and whole wafer scale uniformity is achieved at room temperature in a short time. We have carried out thorough optical characterization for nanopillar black silicon devices to be used for solar cell and plasmonic applications. Cathodoluminescence (CL), current dependent CL spectroscopy, photoluminescence (at room temperature and 77 K), Raman spectroscopy, reflectance and absorption measurement have been performed on the device. A thin layer of Ag is deposited to render with plasmonic property and the plasmonic effect is probed using surface plasmon enhanced fluorescence, angle dependent reflectance measurements, high resolution cathodoluminescence (CL), surface enhanced Raman spectroscopy (SERS) measurement and Fluorescence Lifetime Imaging Microscopy (FLIM) experiment. We obtained reduction in optical reflection of ~ 12 times on b-Si substrate from UV to NIR range, the nanostructured fluorescence enhancement of ~40 times and the Raman scattering enhancement factor of 6.4×107.

  14. Optical emission related to basal-plane stacking faults in m -plane Zn1 -xMgxO epilayers for 0 ≤x ≤0.1

    Science.gov (United States)

    Lin, Wan-Hsien; Corfdir, Pierre; Jahn, Uwe; Grahn, Holger T.

    2016-09-01

    We investigate the optical properties of type-I1 basal-plane stacking faults (BSFs) in ZnO and Zn1 -xMgxO by cathodoluminescence spectroscopy supported by envelope function calculations. We report on a quantum-well-like band alignment of the I1 BSFs in ZnO taking into account the spontaneous polarization as well as an intrinsic self-screening effect on the polarization-related electric field. We present a systematic investigation of the luminescence properties associated with I1 BSFs in Zn1 -xMgxO for varying Mg content (0 ≤x ≤0.1 ) using spatially and spectrally resolved cathodoluminescence spectroscopy. Both the near-band-edge emission and the luminescence line related to the I1 BSF exhibit the expected blueshift and line broadening with increasing Mg content. We propose a band diagram to describe the recombination mechanism of excitons in a Zn1 -xMgxO film containing I1 BSFs. Based on a statistical analysis, we compile the experimentally obtained I1 BSF emission energies of Zn1 -xMgxO samples and establish a linear dependence of the I1 BSF-related emission energy on the Mg content. This correlation provides an alternative way to identify the presence of I1 BSFs in Zn1 -xMgxO without the necessity of sophisticated transmission electron microscopy investigations.

  15. Thermal and electron stimulated luminescence of natural bones, commercial hydroxyapatite and collagen.

    Science.gov (United States)

    Roman-Lopez, J; Correcher, V; Garcia-Guinea, J; Rivera, T; Lozano, I B

    2014-01-01

    The luminescence (cathodoluminescence and thermoluminescence) properties of natural bones (Siberian mammoth and adult elephant), commercial hydroxyapatite and collagen were analyzed. Chemical analyses of the natural bones were determined using by Electron Probe Micro-Analysis (EMPA). Structural, molecular and thermal characteristics were determined by X-ray Diffraction (XRD), Raman spectroscopy and Differential Thermal and Thermogravimetric analysis (DTA-TG). Cathodoluminescence (CL) spectra of natural bones and collagen showed similar intense broad bands at 440 and 490 nm related to luminescence of the tetrahedral anion [Formula: see text] or structural defects. A weaker luminescence exhibited at 310 nm could be attributed to small amount of rare earth elements (REEs). Four luminescent bands at 378, 424, 468 and 576 nm were observed in the commercial hydroxyapatite (HAP). Both natural bones and collagen samples exhibited natural thermoluminescence (NTL) with well-defined glow curves whereas that the induced thermoluminescence (ITL) only appears in the samples of commercial hydroxyapatite and collagen. Additional explanations for the TL anomalous fading of apatite, as a crucial difficulty performing dosimetry and dating, are also considered.

  16. Diagenetic environments of calcite veins hosted in marine carbonate rocks in middle Yangtze region of South China%中扬子海相碳酸盐岩中方解石脉成岩环境研究

    Institute of Scientific and Technical Information of China (English)

    王芙蓉; 何生; 杨兴业

    2011-01-01

    Analyses of thin slices, cathodoluminescence and carbon-oxygen isotope of calcite veins hosted in marine carbonate rocks distributed around Jingshan County in the middle Yangtze region of South China indicated that, two crystal forms including radial calcite and isometric texture calcite could be identified in calcite veins in the Triassic and the cathodoluminescence intensity was different. The Permian and Ordovician fractures were mainly filled with isometric texture calcite veins and the cathodoluminescence intensity was similar with that of the surrounding rocks. The δl3 CPDB value of calcite veins ranged from -6. 76‰ to 4. Ol‰and the δ18 OPDB value ranged from -17. 95‰to -5. 67‰, indicating the marine phreatic environment and the mixing phreatic environment for calcite veins deposition. Calcite veins in the Triassic were sedimentary origin, and part of calcite veins in the Permian and the Ordovician suffered latter diagenetic fluid dissolution. Fluid generated from organic-matter maturation effected the formation of calcite veins in the Permian to some degree.%通过对中扬子京山县城周边露头碳酸盐岩中方解石脉的普通薄片、阴极发光以及碳氧同位索等资料分析,认为该区露头三叠系裂隙中充填放射状和等轴粒状的方解石且阴极发光强度有差异,二叠系和奥陶系裂隙中主要为等轴粒状方解石,阴极发光与围岩相似.方解石脉的δ13CPDB位于-6.76‰~4.01‰之间,δ18OPDB在-17.95‰~-5.67‰之间,基本为海水潜流带一混合水潜流带沉积环境.三叠系方解石脉基本上为沉积碳酸盐岩,二叠系和奥陶系部分方解石脉受后期成岩流体的影响,其中二叠系有饥质成熟产生的流体对该层系方解石脉的形成有一定影响.

  17. Development of efficient, small particle size luminescent oxides using combustion synthesis

    Science.gov (United States)

    Shea, Lauren Elizabeth

    Luminescent materials (phosphors) find application in cathode-ray tubes (CRTs), medical and industrial equipment monitors, fluorescent lamps, xerography, and many types of flat panel displays. Many commercially available phosphors were optimized in the 1960s for high voltage (>10 kV) CRT applications. Recently, a great deal of emphasis has been placed on the development and improvement of phosphors for flat panel displays that operate at low voltages (displays demand high resolution phosphor screens which can only be realized using phosphors with smaller particle size (displays. This technique exploits the exothermic redox reaction of metal nitrates (oxidizers) with an organic fuel (reducing agent). Typical fuels include urea (CHsb4Nsb2O), carbohydrazide (CHsb6Nsb4O), or glycine (Csb2Hsb5NOsb2). Resulting powders were well-crystallized, with a large surface area and small particle size. Phosphor powders were exposed to photoluminescence excitation by high energy (254 nm, E = 4.88 eV) and low energy photons (365 nm, E = 3.4 eV and 435 nm, E = 2.85 eV) and cathodoluminescence excitation by a low-voltage (100-1000 V) electron beam. Photoluminescence (PL) techniques resulted in the measurement of spectral energy distribution and relative intensities. Phosphor efficiencies in lumens per watt (lm/W) were obtained by low-voltage cathodoluminescence measurements. The effects of processing parameters such as type of fuel, fuel to oxidizer ratio, and heating rate were studied. The combustion process was optimized based on these processing parameters in order to maximize the luminescence of the phosphor powders in the as-synthesized condition. An increase in PL intensity with increasing flame temperature of reaction was observed. Post-reaction annealing (1000-1600sp°C) increased the PL intensity and CL efficiency of the as-synthesized powders. Diffusion of the activator ions, particle growth, reduction of residual carbon impurities, disorder surrounding the activator ions

  18. Large area radiation source for water and wastewater treatment

    Science.gov (United States)

    Mueller, Michael T.; Lee, Seungwoo; Kloba, Anthony; Hellmer, Ronald; Kumar, Nalin; Eaton, Mark; Rambo, Charlotte; Pillai, Suresh

    2011-06-01

    There is a strong desire for processes that improve the safety of water supplies and that minimize disinfection byproducts. Stellarray is developing mercury-free next-generation x-ray and UV-C radiation sources in flat-panel and pipe form factors for water and wastewater treatment applications. These new radiation sources are designed to sterilize sludge and effluent, and to enable new treatment approaches to emerging environmental concerns such as the accumulation of estrogenic compounds in water. Our UV-C source, based on cathodoluminescent technology, differs significantly from traditional disinfection approaches using mercury arc lamps or UV LEDs. Our sources accelerate electrons across a vacuum gap, converting their energy into UV-C when striking a phosphor, or x-rays when striking a metallic anode target. Stellarray's large area radiation sources for wastewater treatment allow matching of the radiation source area to the sterilization target area for maximum coverage and improved efficiency.

  19. Morphological dependent Indium incorporation in InGaN/GaN multiple quantum wells structure grown on 4° misoriented sapphire substrate

    Directory of Open Access Journals (Sweden)

    Teng Jiang

    2016-03-01

    Full Text Available The epitaxial layers of InGaN/GaN MQWs structure were grown on both planar and vicinal sapphire substrates by metal organic chemical vapor deposition. By comparing the epitaxial layers grown on planar substrate, the sample grown on 4° misoriented from c-plane toward m-plane substrate exhibited many variations both on surface morphology and optical properties according to the scanning electronic microscopy and cathodoluminescence (CL spectroscopy results. Many huge steps were observed in the misoriented sample and a large amount of V-shape defects located around the boundary of the steps. Atoms force microscopy images show that the steps were inclined and deep grooves were formed at the boundary of the adjacent steps. Phase separation was observed in the CL spectra. CL mapping results also indicated that the deep grooves could effectively influence the localization of Indium atoms and form an In-rich region.

  20. Luminescence de l'europium divalent dans les sulfures de magnésium ou d'éléments alcalino-terreux (sulfures MS, thioaluminates et thiosilicates)

    OpenAIRE

    Le Thi, Kim-Thoa

    1989-01-01

    Dans la perspective de la réalisation de luminophores pour écrans cathodiques, une étude de la luminescence de l'europium dans des réseaux-hôtes soufres caracterisés par une large bande interdite a été réalisée. La première partie porte sur l'élaboration des sulfures MS et la détermination des facteurs influençant leurs rendements de photoluminescence et de cathodoluminescence. La seconde est consacrée a l'étude des systèmes MS-Al2S3 et MS-SiS2. De nouveaux thioaluminates ont ete isoles; les ...

  1. Creation and characterization of He-related color centers in diamond

    CERN Document Server

    Forneris, Jacopo; Tchernij, Sviatoslav Ditalia; Picollo, Federico; Battiato, Alfio; Traina, Paolo; Degiovanni, Ivo; Moreva, Ekaterina; Brida, Giorgio; Grilj, Veljko; Skukan, Natko; Jakšić, Milko; Genovese, Marco; Olivero, Paolo

    2016-01-01

    Diamond is a promising material for the development of emerging applications in quantum optics, quantum information and quantum sensing. The fabrication and characterization of novel luminescent defects with suitable opto-physical properties is therefore of primary importance for further advances in these research fields. In this work we report on the investigation in the formation of photoluminescent (PL) defects upon MeV He implantation in diamond. Such color centers, previously reported only in electroluminescence and cathodoluminescence regime, exhibited two sharp emission lines at 536.5 nm and 560.5 nm, without significant phonon sidebands. A strong correlation between the PL intensities of the above-mentioned emission lines and the He implantation fluence was found in the 10^15-10^17 cm^{-2} fluence range. The PL emission features were not detected in control samples, i.e. samples that were either unirradiated or irradiated with different ion species (H, C). Moreover, the PL emission lines disappeared i...

  2. Phosphorus Doping of Polycrystalline CdTe by Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Colegrove, Eric; Albin, David S.; Guthrey, Harvey; Harvey, Steve; Burst, James; Moutinho, Helio; Farrell, Stuart; Al-Jassim, Mowafak; Metzger, Wyatt K.

    2015-06-14

    Phosphorus diffusion in single crystal and polycrystalline CdTe material is explored using various methods. Dynamic secondary ion mass spectroscopy (SIMS) is used to determine 1D P diffusion profiles. A 2D diffusion model is used to determine the expected cross-sectional distribution of P in CdTe after diffusion anneals. Time of flight SIMS and cross-sectional cathodoluminescence corroborates expected P distributions. Devices fabricated with diffused P exhibit hole concentrations up to low 1015 cm-3, however a subsequent activation anneal enabled hole concentrations greater than 1016 cm-3. CdCl2 treatments and Cu based contacts were also explored in conjunction with the P doping process.

  3. Excitonic localization in AlN-rich AlxGa1−xN/AlyGa1−yN multi-quantum-well grain boundaries

    KAUST Repository

    Ajia, Idris A.

    2014-09-22

    AlGaN/AlGaN multi-quantum-wells (MQW) with AlN-rich grains have been grown by metal organic chemical vapor deposition. The grains are observed to have strong excitonic localization characteristics that are affected by their sizes. The tendency to confine excitons progressively intensifies with increasing grain boundary area. Photoluminescence results indicate that the MQW have a dominant effect on the peak energy of the near-bandedge emission at temperatures below 150 K, with the localization properties of the grains becoming evident beyond 150 K. Cathodoluminescence maps reveal that the grain boundary has no effect on the peak intensities of the AlGaN/AlGaN samples.

  4. Raman mapping of hexagonal hillocks in N-polar GaN grown on c-plane sapphire

    Science.gov (United States)

    Jiang, Teng; Lin, Zhiyu; Zhang, Jincheng; Xu, Shengrui; Huang, Jun; Niu, Mutong; Gao, Xiaodong; Guo, Lixin; Hao, Yue

    2017-04-01

    A large amount of huge hexagonal hillocks were observed on the surface of N-polar GaN film grown on c-plane sapphire substrate by MOCVD. The distribution of residual stress and dislocation density in a typical hexagonal hillock was investigated by the mapping measurement of Micro-Raman and Cathodoluminescence (CL) spectroscopy. It is found that the residual stress at the top region of the hillock is much smaller than that of the sidewall region and the region around the hillock. Meanwhile, the CL images confirmed that the dislocation density around the hexagonal hillock is higher than the top region of the hillock. The bending and annihilation of the dislocations during the growth of the hexagonal hillock result in the relaxation of residual stress which should be responsible for the spatial variation of dislocation density and residual stress.

  5. A combined study of SHRIMP U-Pb dating, trace element and mineral inclusions on high-pressure metamorphic overgrowth zircon in eclogite from Qinglongshan in the Sulu terrane

    Institute of Scientific and Technical Information of China (English)

    LI Qiuli; LI Shuguang; HOU Zhenhui1; HONG Jian; YANG Wei1

    2005-01-01

    Methods recently advanced for discrimination on the genesis of metamorphic zircon, such as analysis of mineral inclusions and trace elements, provide us powerful means to distinguish zircon overgrowth during high-pressure metamorphism. Zircons in ultrahigh-pressure eclogite from Qinglongshan in the Sulu terrane were studied by the SHRIMP U-Pb method in combining with trace element and mineral inclusion analyses. No inherited core was identified in the analyzed zircons by means of cathodoluminescence images. The occurrence of high-pressure metamorphic mineral inclusions in zircon, such as garnet, omphacite, rutile, and the flat HREE pattern in zircon indicate that the zircon formed at high-pressure metamorphic conditions. Therefore, a weighted average U-Pb age of 227.4 ± 3.5 Ma obtained from such a kind of zircon is interpreted to represent the timing of peak metamorphism for the Qinglongshan eclogite.

  6. Native cation vacancies in Si-doped AlGaN studied by monoenergetic positron beams

    Science.gov (United States)

    Uedono, A.; Tenjinbayashi, K.; Tsutsui, T.; Shimahara, Y.; Miyake, H.; Hiramatsu, K.; Oshima, N.; Suzuki, R.; Ishibashi, S.

    2012-01-01

    Native defects in Si-doped AlGaN grown by metalorganic vapor phase epitaxy were probed by monoenergetic positron beams. Doppler broadening spectra of the annihilation radiation and positron lifetimes were measured, and these were compared with results obtained using first-principles calculation. For Si-doped AlxGa1-xN (4 × 1017 Si/cm3), the vacancy-type defects were introduced at above x = 0.54, and this was attributed to the transition of the growth mode to the Stranski-Krastanov mechanism from the Frank-van der Merwe mechanism. For Si-doped Al0.6Ga0.4N, the vacancy concentration increased with increasing Si concentration, and the major defect species was identified as Al vacancies. A clear correlation between the suppression of cathodoluminescence and the defect concentration was obtained, suggesting the cation vacancies act as nonradiative centers in AlGaN.

  7. Ion beam induced luminescence from diamond using an MeV ion microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Bettiol, A.A.; Jamieson, D. N.; Prawer, S.; Allen, M.G. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1993-12-31

    Analysis of the luminescence induced by a MeV ion beam offers the potential to provide useful information about the chemical properties of atoms in crystals to complement the information provided by more traditional Ion Beam Analysis (IBA) such as Rutherford Backscattering Spectrometry (RBS), ion channeling and Particle Induced X-ray Emission (PIXE). Furthermore, the large penetration depth of the MeV ion beam offers several advantages over the relatively shallow penetration of keV electrons typically employed in cathodoluminescence. An Ion Beam Induced Luminescence (IBIL) detection system was developed for the Melbourne microprobe that allows the spatial mapping of the luminescence signal along with the signals from RBS and PIXE. Homoepitaxial diamond growth has been studied and remarkable shifts in the characteristic blue luminescence of diamond towards the green were observed in the overgrowth. This has been tentatively identified as being due to transition metal inclusions in the epitaxial layers. 8 refs., 2 refs.

  8. Influence of surface structure of (0001 sapphire substrate on the elimination of small-angle grain boundary in AlN epilayer

    Directory of Open Access Journals (Sweden)

    Ryan G. Banal

    2015-09-01

    Full Text Available AlN epilayers were grown on (0001 sapphire substrates by metal-organic vapor phase epitaxy, and the influence of the substrate’s surface structure on the formation of in-plane rotation domain is studied. The surface structure is found to change with increasing temperature under H2 ambient. The ML steps of sapphire substrate formed during high-temperature (HT thermal cleaning is found to cause the formation of small-angle grain boundary (SAGB. To suppress the formation of such structure, the use of LT-AlN BL technique was demonstrated, thereby eliminating the SAGB. The BL growth temperature (Tg is also found to affect the surface morphology and structural quality of AlN epilayer. The optical emission property by cathodoluminescence (CL measurement showed higher emission intensity from AlN without SAGB. The LT-AlN BL is a promising technique for eliminating the SAGB.

  9. Evaluation of subsurface damage in GaN substrate induced by mechanical polishing with diamond abrasives

    Energy Technology Data Exchange (ETDEWEB)

    Aida, Hideo, E-mail: h-aida@namiki.net [NJC Institute of Technology, Namiki Precision Jewel Co., Ltd., 3-8-22 Shinden, Adachi, Tokyo 123-8511 (Japan); KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan); Takeda, Hidetoshi; Kim, Seong-Woo; Aota, Natsuko; Koyama, Koji [NJC Institute of Technology, Namiki Precision Jewel Co., Ltd., 3-8-22 Shinden, Adachi, Tokyo 123-8511 (Japan); Yamazaki, Tsutomu; Doi, Toshiro [KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2014-02-15

    The relationship between the depth of the subsurface damage (SSD) and the size of the diamond abrasive used for mechanical polishing (MP) of GaN substrates was investigated in detail. GaN is categorized as a hard, brittle material, and material removal in MP proceeds principally to the fracture of GaN crystals. Atomic force microscopy and cathodoluminescence imaging revealed that the mechanical processing generated surface scratches and SSD. The SSD depth reduced as the diamond abrasive size reduced. A comparison of the relationship between the SSD depth and the diamond abrasive size used in the MP of GaN with the same relationship for typical brittle materials such as glass substrates suggests that the MP of GaN substrates proceeds via the same mechanism as glass.

  10. Decoration of ZnO Nanorods with Coral Reefs like NiO Nanostructures by the Hydrothermal Growth Method and Their Luminescence Study

    Directory of Open Access Journals (Sweden)

    Mazhar Ali Abbasi

    2014-01-01

    Full Text Available Composite nanostructures of coral reefs like p-type NiO/n-type ZnO were synthesized on fluorine-doped tin oxide glass substrates by hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray diffraction techniques. This investigation shows that the adopted synthesis leads to high crystalline quality nanostructures. The morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL spectra for the synthesized composite nanostructures are dominated mainly by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence of the decorated ZnO nanostructures is enhanced by the presence of the NiO.

  11. Growth, Structural and Optical Characterization of ZnO Nanotubes on Disposable-Flexible Paper Substrates by Low-Temperature Chemical Method

    Directory of Open Access Journals (Sweden)

    M. Y. Soomro

    2012-01-01

    Full Text Available We report the synthesis of vertically aligned ZnO nanotubes (NTs on paper substrates by low-temperature hydrothermal method. The growth of ZnO NTs on the paper substrate is discussed; further, the structural and optical properties are investigated by scanning electron microscope (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, energy-dispersive X-ray spectroscopy (EDS, and cathodoluminescence (CL, and it was found that the ZnO NTs on paper substrate fulfill the structural and optical properties of ZnO NTs grown on other conventional substrates. This will be more beneficial in future usage of ZnO NTs in different fields and applications. Particularly, this approach opens the ways in research and development for high volume manufacturing of low-cost, flexible optoelectronics devices on disposable paper substrates and can be used in the future miniaturization trends.

  12. Characterization of submonolayer film composed of soft-landed copper nanoclusters on HOPG

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Shyamal, E-mail: shyamal.mondal@saha.ac.in; Das, Pabitra; Chowdhury, Debasree; Bhattacharyya, S. R. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata-700 064 (India)

    2015-06-24

    Preformed Copper nanoclusters are deposited on highly oriented pyrolytic graphite (HOPG) at very low energy. For the study of chemical composition X-ray Photoelectron Spectroscopy (XPS) is performed for a wide range of binding energy without exposing the sample in the ambient. Morphological aspects of the supported clusters are characterized employing high resolution scanning electron microscope (SEM). Different types of morphology are observed depending on the nature of the substrate surface. Big fractal islands are formed on terraces while at the step edges small islands are found to form. Ex-situ cathodoluminescence (CL) measurement shows peak at 558 nm wavelength which corresponds to the band gap of 2.22 eV which is due to Cu{sub 2}O nanocrystals formed due to oxidation of the deposited film in ambient.

  13. Electrically driven, phosphor-free, white light-emitting diodes using gallium nitride-based double concentric truncated pyramid structures

    Institute of Scientific and Technical Information of China (English)

    Seung-Hyuk Lim; Young-Ho Ko; Christophe Rodriguez; Su-Hyun Gong; Yong-Hoon Cho

    2016-01-01

    White light-emitting diodes (LEDs) are becoming an alternative general light source,with huge energy savings compared to conventional lighting.However,white LEDs using phosphor(s) suffer from unavoidable Stokes energy converting losses,higher manufacturing cost,and reduced thermal stability.Here,we demonstrate electrically driven,phosphor-free,white LEDs based on three-dimensional gallium nitride structures with double concentric truncated hexagonal pyramids.The electroluminescence spectra are stable with varying current.The origin of the emission wavelength is studied by cathodoluminescence and high-angle annular dark field scanning transmission electron microscopy experiments.Spatial variation of the carrier injection efficiency is also investigated by a comparative analysis between spatially resolved photoluminescence and electroluminescence.

  14. Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes.

    Science.gov (United States)

    Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

    2015-11-16

    Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100-270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies.

  15. Characterization of GaN Nanorods Fabricated Using Ni Nanomasking and Reactive Ion Etching: A Top-Down Approach

    Directory of Open Access Journals (Sweden)

    Ashutosh Kumar

    2013-05-01

    Full Text Available Large thermal mismatch between GaN surface and sapphire results in compressive stress in Gallium Nitride (GaN layer which degrades the device performance. Nanostructuring the GaN can reduce this stress leading to reduction in Quantum Confined Stark Effect. Aligned GaN nanorods based nanodevices have potential applications in electronics and optoelectronics. This paper describes the fabrication of GaN nanorods using Ni nanomasking and reactive ion etching. The morphology of GaN nanorods was studied by field emission scanning electron microscopy. The optical properties of GaN nanorods were studied by Cathodoluminescence (CL spectroscopy. CL results revealed the existence of characteristic band-edge luminescence and yellow band luminescence.

  16. On the luminescence of freshly introduced a-screw dislocations in low-resistance GaN

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, O. S., E-mail: o.s.medvedev@spbu.ru; Vyvenko, O. F.; Bondarenko, A. S. [Saint Petersburg State University (Russian Federation)

    2015-09-15

    Using scanning electron microscopy in the cathodoluminescence mode, it is shown that straight segments of a-screw dislocations introduced by plastic deformation at room temperature into unintentionally doped low-resistance gallium nitride luminesce in the spectral range 3.1–3.2 eV at 70 K. The spectral composition of dislocation luminescence shows a fine doublet structure with a component width of ∼15 meV and splitting of ∼30 meV, accompanied by LO-phonon replicas. Luminescent screw dislocations move upon exposure to an electron beam and at low temperatures, but retain immobility for a long time without external excitation. Optical transitions involving the quantum-well states of a stacking fault in a split-dislocation core are considered to be the most probable mechanism of the observed phenomenon.

  17. Re-Os dating of sulphide inclusions zonally distributed in single Yakutian diamonds: Evidence for multiple episodes of Proterozoic formation and protracted timescales of diamond growth

    Science.gov (United States)

    Wiggers de Vries, D. F.; Pearson, D. G.; Bulanova, G. P.; Smelov, A. P.; Pavlushin, A. D.; Davies, G. R.

    2013-11-01

    The timing of diamond formation in the Siberian lithospheric mantle was investigated by Re-Os isotope dating of sulphide inclusions from eclogitic and lherzolitic diamonds from the Mir, 23rd Party Congress and Udachnaya kimberlite pipes in Yakutia. The diamonds contained multiple sulphide inclusions distributed over their core-to-rim zones. Cathodoluminescence, carbon isotope and nitrogen aggregation studies demonstrate that the diamonds are zoned and that the distinct zones are associated with different diamond growth episodes. There are coherent relationships between carbon isotope composition, nitrogen concentration and aggregation state of the diamond hosts, and major and trace element compositions, Re-Os compositions and initial Os isotope ratios of the included sulphides. This suggests that the different diamond and sulphide populations formed at different times from fluids/melts with different chemical compositions. Based on the Re-Os isochron ages and the nitrogen aggregation states we conclude that the sulphides are co-genetic with their diamond hosts.

  18. One-dimensional CdS nanostructures: a promising candidate for optoelectronics.

    Science.gov (United States)

    Li, Huiqiao; Wang, Xi; Xu, Junqi; Zhang, Qi; Bando, Yoshio; Golberg, Dmitri; Ma, Ying; Zhai, Tianyou

    2013-06-11

    As a promising candidate for optoelectronics, one-dimensional CdS nanostructures have drawn great scientific and technical interest due to their interesting fundamental properties and possibilities of utilization in novel promising optoelectronical devices with augmented performance and functionalities. This progress report highlights a selection of important topics pertinent to optoelectronical applications of one-dimensional CdS nanostructures over the last five years. This article begins with the description of rational design and controlled synthesis of CdS nanostructure arrays, alloyed nanostructucures and kinked nanowire superstructures, and then focuses on the optoelectronical properties, and applications including cathodoluminescence, lasers, light-emitting diodes, waveguides, field emitters, logic circuits, memory devices, photodetectors, gas sensors, photovoltaics and photoelectrochemistry. Finally, the general challenges and the potential future directions of this exciting area of research are highlighted.

  19. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes.

    Science.gov (United States)

    Kumar, Ashutosh; Heilmann, M; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M; Christiansen, Silke H; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained.

  20. Rare earth doped glass-ceramics containing NaLaF4 nanocrystals

    Science.gov (United States)

    Elsts, E.; Krieke, G.; Rogulis, U.; Smits, K.; Zolotarjovs, A.; Jansons, J.; Sarakovskis, A.; Kundzins, K.

    2016-09-01

    Oxyfluoride glasses 16Na2O-9NaF-5LaF3-7Al2O3-63SiO2 (mol%) activated with 3% terbium, dysprosium, praseodymium and neodymium fluorides have been prepared and studied by differential thermal analysis, cathodoluminescence, X-ray induced luminescence, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. We found out that the presence of crystalline phase enhances the X-ray induced luminescence intensity. X-ray induced luminescence is the most intense for the sample activated with terbium and treated at 700 °C, whereas the praseodymium and neodymium activated samples have the fastest decay times.

  1. Effects of Nano- and Microscale SiO2 Masks on the Growth of a-Plane GaN Layers on r-Plane Sapphire

    Science.gov (United States)

    Son, Ji-Su; Miao, Cao; Honda, Yoshio; Yamaguchi, Masahito; Amano, Hiroshi; Seo, Yong Gon; Hwang, Sung-Min; Baik, Kwang Hyeon

    2013-08-01

    We report on the combined effects of a-plane GaN layers on a nanoscale patterned insulator on an r-plane sapphire substrate and epitaxial lateral overgrowth (ELOG) techniques. The fully coalescent a-plane GaN layer using nano- and microscale SiO2 masks showed the formation of nano- and microscale voids on the masks, respectively. Atomic force microscopy (AFM) measurements revealed a surface roughness of 0.63 nm and a submicron pit density of ˜7.8 ×107 cm-2. Photoluminescence (PL) intensity was enhanced by a factor of 9.0 in comparison with that of a planar sample. Omega full-width at half-maximum (FWHM) values of the (11bar 20) X-ray rocking curve along the c- and m-axes were 553 and 788 arcsec, respectively. A plan-view cathodoluminescence (CL) mapping image showed high luminescence intensity on the SiO2 masks.

  2. Luminescence of devitrificated non-doped and Eu,Dy and Tm doped wollastonite crystal in glass; Luminescence de cristaux de devitrivication de wollastonite dans des verres non dopes et dopes en Eu,Dy et Tm

    Energy Technology Data Exchange (ETDEWEB)

    El Marraki, A.; Schvoerer, M.; Bechtel, F. [Univ. Michel de Montaigne-Bordeaux 3, Pessac (France). Centre de Recherche en Phys. Appliquee a l' Archeologie

    2000-10-16

    Wollastonite crystals (CaSiO{sub 3}), ''pure'' or doped with rare earth ions, were grown by a devitrification process of a ternary SiO{sub 2}-Na{sub 2}O-CaO glass. The nature of point defects in these crystals was studied. Concerning the non-doped crystals, two trap centers were revealed by thermoluminescence (TL) and identified by electron spin resonance (ESR) using preheating experiments: one is a hole center HC{sub 1} and the other one an electron center whose main characteristic feature is g = 2.0020. Cathodoluminescence (CL) studies showed an important emission band considered as intrinsic. As for the doped crystals (Eu, Dy, Tm), most CL emission bands were identified. With TL, it is shown that Eu acts in wollastonite crystals as an electron trap and also as an emission centre. (orig.)

  3. BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires with tunable red light emission.

    Science.gov (United States)

    Lin, Jing; Huang, Yang; Mi, Jiao; Zhang, Xinghua; Lu, Zunming; Xu, Xuewen; Fan, Ying; Zou, Jin; Tang, Chengchun

    2013-10-11

    We report on the controlled growth of novel BN-coated Ca(1-x)Sr(x)S:Eu nanowires via a solid-liquid-solid process. The Ca(1-x)Sr(x)S solid solution forms as one-dimensional nanowires and has been coated with homogeneous protective BN nanolayers. The structure and luminescence properties of this new nanocomposite have been systematically investigated. High-spatial-resolution cathodoluminescence investigations reveal that effective red color tuning has been achieved by tailoring the composition of the Ca(1-x)Sr(x)S nanowires. Moreover, codoping of Ce(3+) and Eu(2+) in the CaS nanowire can induce energy transfer in the matrix and make it possible to obtain enhanced orange color in the nanowires. The BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires are envisaged to be valuable red-emitting nanophosphors and useful in advanced nanodevices and white LEDs.

  4. Blue-emitting LaAlO{sub 3}:Tm{sup 3+}, In{sup 3+} phosphors for field emission displays

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wenyu [Innermongolia University of Science and Technology, School of Chemistry and Chemical Engineering, Baotou (China); University of Science and Technology Beijng, School of Metallurgical and Ecological Engineering, Beijing (China); An, Shengli [University of Science and Technology Beijng, School of Metallurgical and Ecological Engineering, Beijing (China); Innermongolia University of Science and Technology, School of Material and Metallurgy, Baotou (China); Fan, Bin; Li, Songbo [Innermongolia University of Science and Technology, School of Chemistry and Chemical Engineering, Baotou (China)

    2014-09-15

    Tm{sup 3+} and In{sup 3+} co-doped LaAlO{sub 3} phosphors were prepared by a Pechini sol-gel method and characterized by X-ray diffraction, scanning electron microscope, and cathodoluminescence spectrum. The phosphor is composed of slightly aggregated particles with approximately spherical shape and a narrow size range of 1.0-1.5 μm. Under voltage electron beam excitation, the phosphor shows the characteristic emissions of Tm{sup 3+}. All the color purity, radiant efficiency, luminous efficiency, and stability of the optimum LaAlO{sub 3}:0.01Tm{sup 3+}, 0.04In{sup 3+} phosphor are superior to these of commercial ZnS:Ag,Cl phosphor. These tests suggest that it could be a potential candidate as a blue phosphor for field emission displays. (orig.)

  5. Diagenesis in porosity evolution of opening-mode fractures, Middle Triassic to Lower Jurassic La Boca Formation, NE Mexico

    Science.gov (United States)

    Laubach, Stephen E.; Ward, Meghan E.

    2006-06-01

    Opening-mode fractures (joints) in Middle Triassic to Lower Jurassic La Boca Formation sandstones, northeastern Mexico, have patterns of fracture porosity, mineral-fill structures, and size distributions not previously described from outcrop. Patterns match those found in cores from many basins. We used aperture measurements along lines of observation (scanlines), fracture-trace maps, petrography, high-resolution scanning-electron-microscope-(SEM)-based cathodoluminescence, and fluid inclusions to characterize fracture populations. Open fractures are lined by quartz that precipitated while fractures were opening, whereas sealed fractures additionally contain calcite deposited after fractures ceased opening. Large fractures and arrays of contemporaneous microfractures have consistent power-law aperture-size scaling over approximately three orders of magnitude. Our results imply that open fractures and fracture sizes depend on diagenetic state. The interplay of fracture mechanics and diagenetic history is a determinant on effective porosity within fractures and, thus, open fracture persistence, connectivity, and fluid flow.

  6. Signature of a Fano-resonance in a plasmonic meta-molecule's local density of optical states

    CERN Document Server

    Frimmer, Martin; Koenderink, A Femius

    2011-01-01

    We present measurements on plasmonic meta-molecules under local excitation using cathodoluminescence which show a spatial redistribution of the local density of optical states (LDOS) at the same frequency where a sharp spectral Fano-feature in the extinction cross section has been observed. Our analytical model shows that both near- and far-field effects arise due to interference of the same two eigenmodes of the system. We present quantitative insights both in a bare state, and in a dressed state picture that describe plasmonic Fano interference either as near-field amplitude transfer between three coupled bare states, or as interference of two uncoupled eigenmodes in the far field. We identify the same eigenmode causing a dip in extinction to strongly enhance the radiative LDOS, making it a promising candidate for spontaneous emission control.

  7. Growth and characterization of wurtzite InP/AlGaP core–multishell nanowires with AlGaP quantum well structures

    Science.gov (United States)

    Ishizaka, Fumiya; Hiraya, Yoshihiro; Tomioka, Katsuhiro; Motohisa, Junichi; Fukui, Takashi

    2017-01-01

    We report on the selective-area growth and characterization of wurtzite (WZ) InP/AlGaP core–multishell nanowires. Quantum well (QW) structures were fabricated in AlGaP multishells by changing the alloy composition. Transmission electron microscopy revealed that the AlGaP multishells were grown with a WZ structure on the side of the WZ InP core. The lattice constants of the WZ InP core and WZ AlGaP shell were determined by X-ray diffraction. Cathodoluminescence studies showed that the WZ AlGaP QW with an Al composition of 20% exhibited green emissions at 2.37 eV. These results open the possibility of fabricating green light-emitting diodes using WZ AlGaP-based materials.

  8. Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Y. D.; Shields, P. A.; Allsopp, D. W. E., E-mail: d.allsopp@bath.ac.uk [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom); Bruckbauer, J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2014-11-07

    Cathodoluminescence (CL) hyperspectral imaging has been performed on GaN nanorods containing a single InGaN quantum disk (SQD) with controlled variations in excitation conditions. Two different nanorod diameters (200 and 280 nm) have been considered. Systematic changes in the CL spectra from the SQD were observed as the accelerating voltage of the electron beam and its position of incidence are varied. It is shown that the dominant optical transition in the SQD varies across the nanorod as a result of interplay between the contributions of the deformation potential and the quantum-confined Stark effect to the transition energy as consequence of radial variation in the pseudomorphic strain.

  9. Diverse electron-induced optical emissions from space observatory materials at low temperatures

    Science.gov (United States)

    Dennison, J. R.; Evans Jensen, Amberly; Wilson, Gregory; Dekany, Justin; Bowers, Charles W.; Meloy, Robert

    2013-09-01

    Electron irradiation experiments have investigated the diverse electron-induced optical and electrical signatures observed in ground-based tests of various space observatory materials at low temperature. Three types of light emission were observed: (i); long-duration cathodoluminescence which persisted as long as the electron beam was on (ii) short-duration (polyimides, epoxy resins, and silica glasses) and composite dielectric materials (disordered SiO2 thin films, carbon- and fiberglass-epoxy composites, and macroscopically-conductive carbon-loaded polyimides). We conclude that electron-induced optical emissions resulting from interactions between observatory materials and the space environment electron flux can, in specific circumstances, make significant contributions to the stray light background that could possibly adversely affect the performance of space-based observatories.

  10. Correlation of doping, structure, and carrier dynamics in a single GaN nanorod

    Science.gov (United States)

    Zhou, Xiang; Lu, Ming-Yen; Lu, Yu-Jung; Gwo, Shangjr; Gradečak, Silvija

    2013-06-01

    We report the nanoscale optical investigation of a single GaN p-n junction nanorod by cathodoluminescence (CL) in a scanning transmission electron microscope. CL emission characteristic of dopant-related transitions was correlated to doping and structural defect in the nanorod, and used to determine p-n junction position and minority carrier diffusion lengths of 650 nm and 165 nm for electrons and holes, respectively. Temperature-dependent CL study reveals an activation energy of 19 meV for non-radiative recombination in Mg-doped GaN nanorods. These results directly correlate doping, structure, carrier dynamics, and optical properties of GaN nanostructure, and provide insights for device design and fabrication.

  11. Optical study of a-plane InGaN/GaN multiple quantum wells with different well widths grown by metal-organic chemical vapor deposition

    Science.gov (United States)

    Ko, T. S.; Lu, T. C.; Wang, T. C.; Chen, J. R.; Gao, R. C.; Lo, M. H.; Kuo, H. C.; Wang, S. C.; Shen, J. L.

    2008-11-01

    a-plane InGaN/GaN multiple quantum wells of different widths ranging from 3 to 12 nm grown on r-plane sapphire by metal-organic chemical vapor deposition were investigated. The peak emission intensity of the photoluminescence (PL) reveals a decreasing trend as the well width increases from 3 to 12 nm. Low temperature (9 K) time-resolved PL (TRPL) study shows that the sample with 3-nm-thick wells has the best optical property with a fastest exciton decay time of 0.57 ns. The results of cathodoluminescence and micro-PL scanning images for samples of different well widths further verify that the more uniform and stronger luminescence intensity distribution are observed for the samples of thinner quantum wells. In addition, more effective capturing of excitons due to larger localization energy Eloc and shorter radiative lifetime of localized excitons are observed in thinner well width samples in the temperature dependent TRPL.

  12. An aberration-corrected STEM study of structural defects in epitaxial GaN thin films grown by ion beam assisted MBE.

    Science.gov (United States)

    Poppitz, David; Lotnyk, Andriy; Gerlach, Jürgen W; Lenzner, Jörg; Grundmann, Marius; Rauschenbach, Bernd

    2015-06-01

    Ion-beam assisted molecular-beam epitaxy was used for direct growth of epitaxial GaN thin films on super-polished 6H-SiC(0001) substrates. The GaN films with different film thicknesses were studied using reflection high energy electron diffraction, X-ray diffraction, cathodoluminescence and primarily aberration-corrected scanning transmission electron microscopy techniques. Special attention was devoted to the microstructural characterization of GaN thin films and the GaN-SiC interface on the atomic scale. The results show a variety of defect types in the GaN thin films and at the GaN-SiC interface. A high crystalline quality of the produced hexagonal GaN thin films was demonstrated. The gained results are discussed.

  13. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

    Science.gov (United States)

    Bioud, Youcef A.; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-10-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  14. Physical properties of carbon films obtained by methane pyrolysis in an electric field

    Science.gov (United States)

    Brantov, S. K.; Tereshchenko, A. N.; Shteinman, E. A.; Yakimov, E. B.

    2016-03-01

    A method of synthesizing carbon films on single-crystal silicon substrates by methane pyrolysis in an electrical field is suggested. The pressure and temperature arising in a working chamber when the substrate is exposed to C-4 ions during pyrolysis are measured. Ion bombardment generates nuclei in the form of fibers about 2 μm in diameter providing the growth of a polycrystalline film. The resulting material is examined using electron microscopy and photo- and cathodoluminescence. Synthesized films are a composite material the matrix of which contains nanoclusters of a dissimilar crystalline nature. The effect of considerable two-stage decrease in the resistivity of the film material with increasing temperature from 300 to 1750 K is discovered. This points to the semiconducting properties of thick carbon films.

  15. Cathodo- and photoluminescence increase in amorphous hafnium oxide under annealing in oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, E. V., E-mail: ivanova@mail.ioffe.ru; Zamoryanskaya, M. V. [Ioffe Physical Technical Institute (Russian Federation); Pustovarov, V. A. [Ural State Technical University (Russian Federation); Aliev, V. Sh.; Gritsenko, V. A. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Yelisseyev, A. P. [Russian Academy of Sciences, Institute of Geology and Mineralogy, Siberian Branch (Russian Federation)

    2015-04-15

    Cathodo- and photoluminescence of amorphous nonstoichiometric films of hafnium oxide are studied with the aim to verify the hypothesis that oxygen vacancies are responsible for the luminescence. To produce oxygen vacancies, hafnium oxide was enriched in surplus metal during synthesis. To reduce the oxygen concentration, the film was annealed in oxygen. A qualitative control of the oxygen concentration was carried out by the refractive index. In the initial, almost stoichiometric films we observed a 2.7-eV band in cathodoluminescence. Annealing in oxygen results in a considerable increase in its intensity, as well as in the appearance of new bands at 1.87, 2.14, 3.40, and 3.6 eV. The observed emission bands are supposed to be due to single oxygen vacancies and polyvacancies in hafnium oxide. The luminescence increase under annealing in an oxygen atmosphere may be a result of the emission quenching effect.

  16. Selective-area growth of periodic nanopyramid light-emitting diode arrays on GaN/sapphire templates patterned by multiple-exposure colloidal lithography

    Science.gov (United States)

    Xiong, Zhuo; Wei, Tongbo; Zhang, Yonghui; Zhang, Xiang; Yang, Chao; Liu, Zhiqiang; Yuan, Guodong; Li, Jinmin; Wang, Junxi

    2017-03-01

    Gallium nitride-based nanopyramid light-emitting diodes are a promising technology to achieve highly efficient solid-state lighting and beyond. Here, periodic nanopyramid light-emitting diode arrays on gallium nitride/sapphire templates were fabricated by selective-area metalorganic chemical vapor deposition and multiple-exposure colloidal lithography. The electric field intensity distribution of incident light going through polystyrene microspheres and photoresist are simulated using finite-different time-domain method. Nitrogen as the carrier gas and a low V/III ratio (ratio of molar flow rate of group-V to group-III sources) are found to be important in order to form gallium nitride nanopyramid. In addition, a broad yellow emission in photoluminescence and cathodoluminescence spectra were observed. This phenomena showed the potential of nanopyramid light-emitting diodes to realize long wavelength visible emissions.

  17. Fabrication, self-assembly, and properties of ultrathin AlN/GaN porous crystalline nanomembranes: tubes, spirals, and curved sheets.

    Science.gov (United States)

    Mei, Yongfeng; Thurmer, Dominic J; Deneke, Christoph; Kiravittaya, Suwit; Chen, Yuan-Fu; Dadgar, Armin; Bertram, Frank; Bastek, Barbara; Krost, Alois; Christen, Jürgen; Reindl, Thomas; Stoffel, Mathieu; Coric, Emica; Schmidt, Oliver G

    2009-07-28

    Ultrathin AlN/GaN crystalline porous freestanding nanomembranes are fabricated on Si(111) by selective silicon etching, and self-assembled into various geometries such as tubes, spirals, and curved sheets. Nanopores with sizes from several to tens of nanometers are produced in nanomembranes of 20-35 nm nominal thickness, caused by the island growth of AlN on Si(111). No crystal-orientation dependence is observed while releasing the AlN/GaN nanomembranes from the Si substrate indicating that the driving stress mainly originates from the zipping effect among islands during growth. Competition between different relaxation mechanisms is experimentally revealed for different nanomembrane geometries and well-described by numerical calculations. The cathodoluminescence emission from GaN nanomembranes reveals a weak peak close to the GaN bandgap, which is dramatically enhanced by electron irradiation.

  18. Factors affecting the luminescence emission of InGaN multi-quantum wells grown on (0001) sapphire substrates by MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Oscar; Jimenez, Juan [GdS-Optronlab, Edificio I+D, Univ. de Valladolid, Paseo de Belen 1, 47011 Valladolid (Spain); Avella, Manuel [GdS-Optronlab, Edificio I+D, Univ. de Valladolid, Paseo de Belen 1, 47011 Valladolid (Spain); Parque Cientifico, Edificio I+D, Univ. de Valladolid, Paseo de Belen 1, 47011 Valladolid (Spain); Bosi, Matteo [IMEM-CNR Institute, Area delle Scienze 37/A, 43124 Fontanini, Parma (Italy); Fornari, Roberto [Institute for Crystal Growth (IKZ), Max Born Str. 2, 12489 Berlin (Germany)

    2010-01-15

    The luminescence emission of InGaN/GaN multi-quantum wells (MQW) is affected by several factors, i.e. the composition, the QW thickness, the piezoelectric field and the high density of threading dislocations. In the case of heterostructures containing several QWs piled up, one has to consider the homogeneity of each QW and the thickness of the barrier layers between them, which have influence on the strain. We present herein a cathodoluminescence (CL) study of a series of InGaN QW structures, paying special emphasis to the problem of the lateral distribution of In, and how it influences the emission properties of the QWs. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Luminescence, vibrational and XANES studies of AlN nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Bellucci, S. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Popov, A.I. [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Institute for Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Balasubramanian, C. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Department of Environmental, Occupational and Social Medicine, University of Rome Tor Vergata, 00133 Rome (Italy); Cinque, G.; Marcelli, A. [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Karbovnyk, I. [Ivan Franko National University of Lviv, Faculty of Electronics, 107 Tarnavskogo str., 79017 Lviv (Ukraine)], E-mail: ivan_karbovnyck@yahoo.com; Savchyn, V.; Krutyak, N. [Ivan Franko National University of Lviv, Faculty of Electronics, 107 Tarnavskogo str., 79017 Lviv (Ukraine)

    2007-04-15

    The paper reports comparative studies on synthesized aluminium nitride nanotubes, nanoparticles and commercially available micron-sized AlN powder using different spectroscopic techniques: cathodoluminescence measurements (CL), X-ray absorption near edge spectroscopy (XANES) and Fourier-transform infrared spectroscopy (FTIR). Crucial distinctions in CL spectra are observed for nano- and microsized aluminium nitride powders; systematic shift of the IR absorption maximum has been detected for nanostructured aluminium nitride as compared to commercial samples. Through XANES experiments on Al K-edge structural differences between nano- and bulk AlN are revealed, intensity of features in absorption spectra has been found to be a function of wurtzite and zincblend phases amount in nanostructured samples.

  20. Enhanced random lasing in ZnO nanocombs assisted by Fabry-Perot resonance.

    Science.gov (United States)

    Chen, Yungting; Chen, Yangfang

    2011-04-25

    The ultraviolet random lasing behavior of an ensemble of ZnO nanocombs has been demonstrated. It is found that the Fabry-Perot resonance induced by nanocomb geometry can greatly enhance random lasing action with a low threshold condition. Besides, the emission spectra exhibit few sharp lasing peaks with a full width at half maximum (FWHM) of less than 0.3 nm and a narrow background emission with a FWHM of about 5 nm. Cathodoluminescence mapping images are utilized to analyze the Fabry-Perot resonance phenomenon. The resonant effect on the lasing system is further confirmed by nanocombs with different resonant cavity lengths. The unique lasing behavior induced by the simultaneous occurrence of Fabry-Perot resonance and random laser action shown here may open up a new possibility for the creation of highly efficient light emitting devices.

  1. Direct experimental determination of the spontaneous polarization of GaN

    Science.gov (United States)

    Lähnemann, Jonas; Brandt, Oliver; Jahn, Uwe; Pfüller, Carsten; Roder, Claudia; Dogan, Pinar; Grosse, Frank; Belabbes, Abderrezak; Bechstedt, Friedhelm; Trampert, Achim; Geelhaar, Lutz

    2012-08-01

    We present a universal approach for determining the spontaneous polarization Psp of a wurtzite semiconductor from the emission energies of excitons bound to the different types of stacking faults in these crystals. Employing microphotoluminescence and cathodoluminescence spectroscopy, we observe emission lines from the intrinsic and extrinsic stacking faults in strain-free GaN microcrystals. By treating the polarization sheet charges associated with these stacking faults as a plate capacitor, Psp can be obtained from the observed transition energies with no additional assumptions. Self-consistent Poisson-Schrödinger calculations, aided by the microscopic electrostatic potential computed using density-functional theory, lead to nearly identical values for Psp. Our recommended value for Psp of GaN is -0.022±0.007 C/m2.

  2. Control of optical properties of ZnO nanostructures grown by a novel two-step synthesis approach

    Science.gov (United States)

    Rehman, Naeem-ur-; Mehmood, Mazhar; Rizwan, Rashid; Rasheed, Muhammad Asim; Ling, Francis Chi Chung; Younas, Muhammad

    2014-08-01

    Wurtzite ZnO has been grown by electro-deposition of zinc on copper substrate followed by its hydrothermal oxidation in NaCl solution at 100-130 °C. Scanning electron microscopy has revealed the formation of nanowires and nanorods (with a diameter of about 100 nm to more 1 μm); and microtubes are numerously formed with a diameter of up to 3 μm. For microtubes of various diameters, the wall thickness remained about 0.9 μm. Optical studies illustrated strong ultraviolet emission in the photoluminescence and cathodoluminescence spectra without green luminescence, which suggests that high-quality ZnO structures are formed by our technique for ultraviolet photonic devices.

  3. In situ monitoring of stacking fault formation and its carrier lifetime mediation in p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin, E-mail: chenbinmse@gmail.com; Chen, Jun; Yao, Yuanzhao; Sekiguchi, Takashi [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Matsuhata, Hirofumi; Okumura, Hajime [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)

    2014-07-28

    Using the fine control of an electron beam (e-beam) in scanning electron microscopy with the capabilities of both electrical and optical imaging, the stacking fault (SF) formation together with its tuning of carrier lifetime was in situ monitored and investigated in p-type 4H-SiC homoepitaxial films. The SFs were formed through engineering basal plane dislocations with the energy supplied by the e-beam. The e-beam intensity required for the SF formation in the p-type films was ∼100 times higher than that in the n-type ones. The SFs reduced the minority-carrier lifetime in the p-type films, which was opposite to that observed in the n-type case. The reason for the peculiar SF behavior in the p-type 4H-SiC is discussed with the cathodoluminescence results.

  4. Chronological record of the Early Mesozoic underplating in the northern margin of North China-U-Pb chronometry of zircons in the Late Mesozoic andesite from Western Liaoning

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cathodoluminescence spectroscopic analysis of zircons in the uppermost sanukites of the early Cretaceous Yixian Formation in Western Liaoning reveals zoning structures of the zircons in the volcanic rocks. LA-ICP-MS chronometry shows that the central part of the zircons is remnant zircon with a U-Pb dating of 254 Ma, which is consistent with the age of the Early Mesozoic underplating granulites, and that the periphery is zircon crystallizing out of the host magma with a U-Pb dating of 116 Ma, which is highly consistent with the Ar-Ar dating of the host volcanic rocks. Compositions of the clinopyroxenes xenocrystals in the sanukites are similar to those of the clinopyroxenes in the underplating granulites, indicating that the granulites accreted to the lower crust in the Early Mesozoic have been reformed and disrupted by the upwelling diapers of the asthenosphere and taken part in formation of the sanukites in the Late Mesozoic.

  5. Advances in the In-House CdTe Research Activities at NREL

    Energy Technology Data Exchange (ETDEWEB)

    Gessert, T.; Wu, X.; Dhere, R.; Moutinho, H.; Smith, S.; Romero, M.; Zhou, J.; Duda, A.; Corwine, C.

    2005-01-01

    NREL in-house CdTe research activities have impacted a broad range of recent program priorities. Studies aimed at industrially relevant applications have produced new materials and processes that enhance the performance of devices based on commercial materials (e.g., soda-lime glass, SnO2:F). Preliminary tests of the effectiveness of these novel components using large-scale processes have been encouraging. Similarly, electro- and nano-probe techniques have been developed and used to study the evolution and function of CdTe grain boundaries. Finally, cathodoluminescence (CL) and photoluminescence (PL) studies on single-crystal samples have yielded improved understanding of how various processes may combine to produce important defects in CdTe films.

  6. Light-hole exciton in a nanowire quantum dot

    Science.gov (United States)

    Jeannin, Mathieu; Artioli, Alberto; Rueda-Fonseca, Pamela; Bellet-Amalric, Edith; Kheng, Kuntheak; André, Régis; Tatarenko, Serge; Cibert, Joël; Ferrand, David; Nogues, Gilles

    2017-01-01

    Quantum dots inserted inside semiconductor nanowires are extremely promising candidates as building blocks for solid-state-based quantum computation and communication. They provide very high crystalline and optical properties and offer a convenient geometry for electrical contacting. Having a complete determination and full control of their emission properties is one of the key goals of nanoscience researchers. Here we use strain as a tool to create in a single magnetic nanowire quantum dot a light-hole exciton, an optically active quasiparticle formed from a single electron bound to a single light hole. In this frame, we provide a general description of the mixing within the hole quadruplet induced by strain or confinement. A multi-instrumental combination of cathodoluminescence, polarization-resolved Fourier imaging, and magneto-optical spectroscopy, allows us to fully characterize the hole ground state, including its valence band mixing with heavy-hole states.

  7. Four-probe scanning tunnelling microscope with atomic resolution for electrical and electro-optical property measurements of nanosystems

    Institute of Scientific and Technical Information of China (English)

    Lin Xiao; He Xiao-Bo; Lu Jun-Ling; Gao Li; Huan Qing; Shi Dong-Xia; Gao Hong-Jun

    2005-01-01

    We demonstrate a special four-probe scanning tunnelling microscope (STM) system in ultrahigh vacuum (UHV),which can provide coarse positioning for every probe independently with the help of scanning electron microscope (SEM)and fine positioning down to nanometre using the STM technology. The system allows conductivity measurement by means of a four-point probe method, which can draw out more accurate electron transport characteristics in nanostructures, and provides easy manipulation of low dimension materials. All measurements can be performed in variable temperature (from 30K to 500K), magnetic field (from 0 to 0.1T), and different gas environments. Simultaneously, the cathodoluminescence (CL) spectrum can be achieved through an optical subsystem. Test measurements using some nanowire samples show that this system is a powerful tool in exploring electron transport characteristics and spectra in nanoscale physics.

  8. Molecular nitrogen acceptors in ZnO nanowires induced by nitrogen plasma annealing

    Science.gov (United States)

    Ton-That, C.; Zhu, L.; Lockrey, M. N.; Phillips, M. R.; Cowie, B. C. C.; Tadich, A.; Thomsen, L.; Khachadorian, S.; Schlichting, S.; Jankowski, N.; Hoffmann, A.

    2015-07-01

    X-ray absorption near-edge spectroscopy, photoluminescence, cathodoluminescence, and Raman spectroscopy have been used to investigate the chemical states of nitrogen dopants in ZnO nanowires. It is found that nitrogen exists in multiple states: NO,NZn, and loosely bound N2 molecule. The results establish a direct link between a donor-acceptor pair emission at 3.232 eV and the concentration of loosely bound N2. This work confirms that N2 at Zn site is a potential candidate for producing a shallow acceptor state in N-doped ZnO as theoretically predicted by Lambrecht and Boonchun [Phys. Rev. B 87, 195207 (2013), 10.1103/PhysRevB.87.195207]. Additionally, shallow acceptor states arising from NO complexes have been ruled out in this paper.

  9. Barrier inhomogeneities limited current and 1/f noise transport in GaN based nanoscale Schottky barrier diodes

    Science.gov (United States)

    Kumar, Ashutosh; Heilmann, M.; Latzel, Michael; Kapoor, Raman; Sharma, Intu; Göbelt, M.; Christiansen, Silke H.; Kumar, Vikram; Singh, Rajendra

    2016-01-01

    The electrical behaviour of Schottky barrier diodes realized on vertically standing individual GaN nanorods and array of nanorods is investigated. The Schottky diodes on individual nanorod show highest barrier height in comparison with large area diodes on nanorods array and epitaxial film which is in contrast with previously published work. The discrepancy between the electrical behaviour of nanoscale Schottky diodes and large area diodes is explained using cathodoluminescence measurements, surface potential analysis using Kelvin probe force microscopy and 1ow frequency noise measurements. The noise measurements on large area diodes on nanorods array and epitaxial film suggest the presence of barrier inhomogeneities at the metal/semiconductor interface which deviate the noise spectra from Lorentzian to 1/f type. These barrier inhomogeneities in large area diodes resulted in reduced barrier height whereas due to the limited role of barrier inhomogeneities in individual nanorod based Schottky diode, a higher barrier height is obtained. PMID:27282258

  10. Biexciton emission and crystalline quality of ZnO nano-objects

    Energy Technology Data Exchange (ETDEWEB)

    Corfdir, Pierre; Abid, Mohamed; Papa, Elisa; Ansermet, Jean-Philippe; Ganiere, Jean-Daniel; Deveaud-Pledran, BenoIt [Institute of Condensed Matter Physics, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Mouti, Anas; Stadelmann, Pierre A, E-mail: pierre.corfdir@epfl.ch [Centre Interdisciplinaire de Microscopie Electronique, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland)

    2011-07-15

    The design of cost-effective standards for the quality of nano-objects is currently a key issue toward their massive use for optoelectronic applications. The observation by photoluminescence of narrow excitonic and biexcitonic emission lines in semiconductor nanowires is usually accepted as evidence for high structural quality. Here, we perform time-resolved cathodoluminescence experiments on isolated ZnO nanobelts grown by chemical vapor deposition. We observe narrow emission lines at low temperature, together with a clear biexciton line. Still, drastic alterations in both the CL intensity and lifetime are observed locally along the nano-object. We attribute these to non-radiative recombinations at edge dislocations, closing basal plane stacking faults, inhomogeneously distributed along the NB length. This leads us to the conclusion that the observation of narrow excitonic and biexcitonic emission lines is far from sufficient to grade the quality of a nano-object.

  11. Impact of Mg content on native point defects in Mg{sub x}Zn{sub 1−x}O (0 ≤ x ≤ 0.56)

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, J.; Foster, G. M. [Department of Physics, The Ohio State University, 191 West Woodruff Ave., Columbus, Ohio 43210 (United States); Myer, M.; Mehra, S. [Columbus School for Girls, 56 S. Columbia Ave., Columbus, Ohio 43209 (United States); Chauveau, J. M. [Centre de Recherche sur l’Hetero-Epitaxie et ses Applications, Centre National de la Recherche Scientifique (CRHEA-CNRS), Rue B. Gregory, F-06560 Valbonne Sophia Antipolis (France); University of Nice Sophia Antipolis, Parc Valrose, F-06102 Nice Cedex 2 (France); Hierro, A. [Dpto. Ingeniería Electrónica and ISOM, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Redondo-Cubero, A. [Dpto. Física Aplicada y Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Windl, W. [Department of Materials Science and Engineering, The Ohio State University, 2041 College Road N., Columbus, Ohio 43210 (United States); Brillson, L. J., E-mail: brillson.1@osu.edu [Department of Physics, The Ohio State University, 191 West Woodruff Ave., Columbus, Ohio 43210 (United States); Department of Electrical and Computer Engineering, The Ohio State University, 2015 Neil Avenue, Columbus, Ohio 43210-1272 (United States); Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-06-01

    We used depth-resolved cathodoluminescence spectroscopy and surface photovoltage spectroscopy to measure the densities, energy levels, and spatial distributions of zinc/magnesium cation and oxygen vacancies in isostructural, single-phase, non-polar Mg{sub x}Zn{sub 1−x}O alloys over a wide (0 ≤ x ≤ 0.56) range. Within this wide range, both defect types exhibit strong Mg content-dependent surface segregation and pronounced bulk density minima corresponding to unit cell volume minima, which can inhibit defect formation due to electrostatic repulsion. Mg in ZnO significantly reduces native defect densities and their non-polar surface segregation, both major factors in carrier transport and doping of these oxide semiconductors.

  12. Analysis of defect-related inhomogeneous electroluminescence in InGaN/GaN QW LEDs

    Science.gov (United States)

    Ren, C. X.; Rouet-Leduc, B.; Griffiths, J. T.; Bohacek, E.; Wallace, M. J.; Edwards, P. R.; Hopkins, M. A.; Allsopp, D. W. E.; Kappers, M. J.; Martin, R. W.; Oliver, R. A.

    2016-11-01

    The inhomogeneous electroluminescence (EL) of InGaN/GaN quantum well light emitting diode structures was investigated in this study. Electroluminescence hyperspectral images showed that inhomogeneities in the form of bright spots exhibited spectrally blue-shifted and broadened emission. Scanning electron microscopy combined with cathodoluminescence (SEM-CL) was used to identify hexagonal pits at the centre of approximately 20% of these features. Scanning transmission electron microscopy imaging with energy dispersive X-ray spectroscopy (STEM-EDX) indicated there may be p-doped AlGaN within the active region caused by the presence of the pit. Weak beam dark-field TEM (WBDF-TEM) revealed the presence of bundles of dislocations associated with the pit, suggesting the surface features which cause the inhomogeneous EL may occur at coalescence boundaries, supported by trends in the number of features observed across the wafer.

  13. Compositionally graded relaxed AlGaN buffers on semipolar GaN for mid-ultraviolet emission

    Energy Technology Data Exchange (ETDEWEB)

    Young, Erin C.; Wu Feng; Haeger, Daniel A.; Nakamura, Shuji; Denbaars, Steven P.; Cohen, Daniel A.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Romanov, Alexey E. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Ioffe Physico-Technical Institute Russian Academy of Science, St. Petersburg, 194021 (Russian Federation); Institute of Physics, University of Tartu, Tartu 194021 (Estonia)

    2012-10-01

    In this Letter, we report on the growth and properties of relaxed, compositionally graded Al{sub x}Ga{sub 1-x}N buffer layers on freestanding semipolar (2021) GaN substrates. Continuous and step compositional grades with Al concentrations up to x = 0.61 have been achieved, with emission wavelengths in the mid-ultraviolet region as low as 265 nm. Coherency stresses were relaxed progressively throughout the grades by misfit dislocation generation via primary (basal) slip and secondary (non-basal) slip systems. Threading dislocation densities in the final layers of the grades were less than 10{sup 6}/cm{sup 2} as confirmed by plan-view transmission electron microscopy and cathodoluminescence studies.

  14. Great blue-shift of luminescence of ZnO nanoparticle array constructed from ZnO quantum dots

    Directory of Open Access Journals (Sweden)

    Wang Nengwen

    2011-01-01

    Full Text Available Abstract ZnO nanoparticle array has been fabricated on the Si substrate by a simple thermal chemical vapor transport and condensation without any metal catalysts. This ZnO nanoparticles array is constructed from ZnO quantum dots (QDs, and half-embedded in the amorphous silicon oxide layer on the surface of the Si substrate. The cathodoluminescence measurements showed that there is a pronounced blue-shift of luminescence comparable to those of the bulk counterpart, which is suggested to originate from ZnO QDs with small size where the quantum confinement effect can work well. The fabrication mechanism of the ZnO nanoparticle array constructed from ZnO QDs was proposed, in which the immiscible-like interaction between ZnO nuclei and Si surface play a key role in the ZnO QDs cluster formation. These investigations showed the fabricated nanostructure has potential applications in ultraviolet emitters.

  15. Local measurement of conduction band offset for ZnCdS/ZnSSe nano-structure by Laplace current DLTS cooperated with AFM technique

    Energy Technology Data Exchange (ETDEWEB)

    Litvinov, Vladimir [P.N. Lebedev Physical Institute RAS, Leninsky pr. 53, 119991 Moscow (Russian Federation); Ryazan State Radioengineering University, Gagarina 59/1, 390005 Ryazan (Russian Federation); Kozlovsky, Vladimir; Sannikov, Denis; Sviridov, Dmitry [P.N. Lebedev Physical Institute RAS, Leninsky pr. 53, 119991 Moscow (Russian Federation); Milovanova, Oksana; Rybin, Nikolay [Ryazan State Radioengineering University, Gagarina 59/1, 390005 Ryazan (Russian Federation)

    2010-06-15

    ZnCdS/ZnSSe SQW structure were investigated by current deep level transient spectroscopy (DLTS) with Laplace transform cooperated with atomic force microscopy (AFM) for the first time. Cathodoluminescence (CL) measurements were carried out also. Basing on Laplace current DLTS with AFM and CL data we estimated the conduction band offset of the ZnCdS/ZnSSe interface in the different regions of the structure. Size of the investigated region was commensurable with the diameter of cantilever tip. We demonstrated that Laplace current DLTS-spectrometer switched in the circuit of an AFM cantilever may be used for an investigation of nanostructures. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Identification of dislocation-related luminescence participating levels in silicon by DLTS and Pulsed-CL profiling

    Science.gov (United States)

    Bondarenko, Anton; Vyvenko, Oleg; Isakov, Ivan

    2011-02-01

    We present a study of the dislocation network that occurs in the space charge region of a Schottky diode, by means of DLTS and our recently developed cathodoluminescent (CL) technique called Pulsed-CL. The details of the Pulsed-CL technique are provided. We establish a correspondence between the CL spectra of dislocation-related luminescence in silicon in the vicinity of the so-called D1 band and levels determined from DLTS measurements. The centres responsible for the 815 meV CL component are related to dislocations cores while the centres responsible for the 795 meV CL component are related to some defects outside of the dislocation cores.

  17. Optical properties of single ZnTe nanowires grown at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Artioli, A.; Stepanov, P.; Den Hertog, M.; Bougerol, C.; Genuist, Y.; Donatini, F.; André, R.; Nogues, G.; Tatarenko, S.; Ferrand, D.; Cibert, J. [Inst NEEL, Universiy of Grenoble Alpes, F-38042 Grenoble (France); Inst NEEL, CNRS, F-38042 Grenoble (France); Rueda-Fonseca, P. [Inst NEEL, Universiy of Grenoble Alpes, F-38042 Grenoble (France); Inst NEEL, CNRS, F-38042 Grenoble (France); INAC, CEA and Université de Grenoble, 17 rue des Martyrs, 38054 Grenoble (France); Bellet-Amalric, E.; Kheng, K. [INAC, CEA and Université de Grenoble, 17 rue des Martyrs, 38054 Grenoble (France)

    2013-11-25

    Optically active gold-catalyzed ZnTe nanowires have been grown by molecular beam epitaxy, on a ZnTe(111) buffer layer, at low temperature (350 °C) under Te rich conditions, and at ultra-low density (from 1 to 5 nanowires per μm{sup 2}). The crystalline structure is zinc blende as identified by transmission electron microscopy. All nanowires are tapered and the majority of them are <111> oriented. Low temperature micro-photoluminescence and cathodoluminescence experiments have been performed on single nanowires. We observe a narrow emission line with a blue-shift of 2 or 3 meV with respect to the exciton energy in bulk ZnTe. This shift is attributed to the strain induced by a 5 nm-thick oxide layer covering the nanowires, and this assumption is supported by a quantitative estimation of the strain in the nanowires.

  18. Present State of Electron Backscatter Diffraction and Prospective Developments

    Energy Technology Data Exchange (ETDEWEB)

    Schwarzer, R A; Field, D P; Adams, B L; Kumar, M; Schwartz, A J

    2008-10-24

    Electron backscatter diffraction (EBSD), when employed as an additional characterization technique to a scanning electron microscope (SEM), enables individual grain orientations, local texture, point-to-point orientation correlations, and phase identification and distributions to be determined routinely on the surfaces of bulk polycrystals. The application has experienced rapid acceptance in metallurgical, materials, and geophysical laboratories within the past decade (Schwartz et al. 2000) due to the wide availability of SEMs, the ease of sample preparation from the bulk, the high speed of data acquisition, and the access to complementary information about the microstructure on a submicron scale. From the same specimen area, surface structure and morphology of the microstructure are characterized in great detail by the relief and orientation contrast in secondary and backscatter electron images, element distributions are accessed by energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS), or cathodoluminescence analysis, and the orientations of single grains and phases can now be determined, as a complement, by EBSD.

  19. Spatial luminescence imaging of dopant incorporation in CdTe Films

    Science.gov (United States)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt K.; Al-Jassim, Mowafak

    2017-01-01

    State-of-the-art cathodoluminescence (CL) spectrum imaging with spectrum-per-pixel CL emission mapping is applied to spatially profile how dopant elements are incorporated into Cadmium telluride (CdTe). Emission spectra and intensity monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on computational modeling. Our results show that grain boundaries play a role in incorporating dopants in CdTe exposed to copper, phosphorus, and intrinsic point defects in CdTe. The image analysis provides critical, unique feedback to understand dopant incorporation and activation in the inhomogeneous CdTe material, which has struggled to reach high levels of hole density.

  20. Spatial luminescence imaging of dopant incorporation in CdTe Films

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt K.; Al-Jassim, Mowafak

    2017-01-28

    State-of-the-art cathodoluminescence (CL) spectrum imaging with spectrum-per-pixel CL emission mapping is applied to spatially profile how dopant elements are incorporated into Cadmium telluride (CdTe). Emission spectra and intensity monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on computational modeling. Our results show that grain boundaries play a role in incorporating dopants in CdTe exposed to copper, phosphorus, and intrinsic point defects in CdTe. The image analysis provides critical, unique feedback to understand dopant incorporation and activation in the inhomogeneous CdTe material, which has struggled to reach high levels of hole density.

  1. Spatial Distribution of Dopant Incorporation in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt; Al-Jassim, Mowafak

    2016-11-21

    In this work we use state-of-the-art cathodoluminescence (CL) spectrum imaging that provides spectrum-per-pixel mapping of the CL emission to examine how dopant elements are incorporated into CdTe. Emission spectra and intensity are used to monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on theoretical modeling. Our results show that grain boundaries play a role in the incorporation of dopants in CdTe, whether intrinsic or extrinsic. This type of analysis is crucial for providing feedback to design different processing schedules that optimize dopant incorporation in CdTe photovoltaic material, which has struggled to reach high carrier concentration values. Here, we present results on CdTe films exposed to copper, phosphorus, and intrinsic doping treatments.

  2. Probing light emission from quantum wells within a single nanorod

    Science.gov (United States)

    Bruckbauer, Jochen; Edwards, Paul R.; Bai, Jie; Wang, Tao; Martin, Robert W.

    2013-09-01

    Significant improvements in the efficiency of optoelectronic devices can result from the exploitation of nanostructures. These require optimal nanocharacterization techniques to fully understand and improve their performance. In this study we employ room temperature cathodoluminescence hyperspectral imaging to probe single GaN-based nanorods containing multiple quantum wells (MQWs) with a simultaneous combination of very high spatial and spectral resolution. We have investigated the strain state and carrier transport in the vicinity of the MQWs, demonstrating the high efficiencies resulting from reduced electric fields. Power-dependent photoluminescence spectroscopy of arrays of these nanorods confirms that their fabrication results in partial strain relaxation in the MQWs. Our technique allows us to interrogate the structures on a sufficiently small length scale to be able to extract the important information.

  3. Metamorphic fluid flow in the northeastern part of the 3.8-3.7 Ga Isua Greenstone Belt (SW Greenland): A re-evalution of fluid inclusion evidence for early Archean seafloor-hydrothermal systems

    DEFF Research Database (Denmark)

    Heijlen, Wouter; Appel, P. W. U.; Frezzotti, M. L.;

    2006-01-01

    segregations showed that they were affected by variable recrystallization which controlled their fluid inclusion content. The oldest unaltered fluid inclusions found are present in vein crystals that survived dynamic and static recrystallization. These crystals contain a cogenetic, immiscible assemblage of CO2......-NaCl (0.2-3.7 eq. wt% NaCl.) These successive fluid inclusion assemblages record a retrograde P-T evolution close to a geothermal gradient of similar to 30 degrees C/km, but also indicate fluid pressure variations and the introduction of highly reducing fluids at similar to 200-300 degrees C and 0......Fluid inclusions in quartz globules and quartz veins of a 3.8-3.7 Ga old, well-preserved pillow lava breccia in the northeastern Isua Greenstone Belt (IGB) were studied using microthermometry, Raman spectrometry and SEM Cathodoluminescence Imaging. Petrographic study of the different quartz...

  4. Microcharacterization of CdTe films deposited by close-spaced sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Matson, R.J.; Hasoon, F.S.; Jones, K.M.; Al-Jassim, M.M. (National Renewable Energy Lab., Golden, CO (United States)); Tomlinson, R.D. (Salford Univ. (United Kingdom))

    1994-07-01

    Microcharacterization of the luminescent, structural, electrical and topographical properties of thin films of close-spaced sublimation (CSS)-fabricated CdTe was performed. The film morphology was found to be dependent on the film thickness, deposition conditions and post-deposition treatment. The complementary use of electron beam-induced current (EBIC) and cathodoluminescence (CL) analysis in the scanning electron microscope demonstrated large inter- and intragrain inhomogeneities in the luminescent and electrical properties of the films. Follow-on plan-view examinations with the transmission electron microscope revealed varying densities of structural defects, such as stacking faults and threading dislocations, which could explain the variations observed in the CL and EBIC images. (author)

  5. Properties and behavior of quartz for the silicon process

    Energy Technology Data Exchange (ETDEWEB)

    Aasly, Kurt

    2008-07-01

    fluorescence light microscopy of polished thin sections, cathodoluminescence microscopy and spectroscopy and x-ray diffraction. Combining high-temperature microthermometry and shock-heating investigations has proved to provide useful knowledge about the effects of high temperatures on quartz. Results from earlier research have been confirmed showing that mica is the cause of the effects seen in the temperature interval 900 - 1000 degrees Celsius. This has been shown by the total absence of tridimite in the samples and the fact that mica has been seen in the unheated reference samples. Cathodoluminescence microscopy and spectroscopy was used to investigate sample from shock-heating experiments and corresponding reference samples. These investigations show that cathodoluminescence is a useful tool for petrographic investigations of quartz. The shock-heated samples showed a significant change in cathodoluminescence characteristics that need to be investigated further to understand the cause of these changes. A spotted red luminescence was seen in two of the samples indicating the formation of cristobalite or the transition phase within these samples. Cristobalite has been shown in samples after heating to different temperatures in the interval 1250 to 1550 degrees Celsius, although in different amount in the different types of quartz. However, the transformation rates seem to be more similar after prolonged heating at the highest temperature. Experiments also indicate that the quartzcristobalite transformation may be a cause of the disintegration of quartz at high temperatures. This is related to the severe volume expansion as the quartz transforms to cristobalite via the amorphous intermediate transition phase. The last paper presented in the thesis presents investigations of two furnaces that have been producing ferrosilicon and silicon metal respectively. The results from these investigations show that cristobalite is formed relatively rapidly inside the furnace, however

  6. Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells.

    Directory of Open Access Journals (Sweden)

    Miguel Moreno-Azanza

    Full Text Available Abnormalities in the histo- and ultrastructure of the amniote eggshell are often related to diverse factors, such as ambient stress during egg formation, pathologies altering the physiology of the egg-laying females, or evolutionarily selected modifications of the eggshell structure that vary the physical properties of the egg, for example increasing its strength so as to avoid fracture during incubation. When dealing with fossil materials, all the above hypotheses are plausible, but a detailed taphonomical study has to be performed to rule out the possibility that secondary processes of recrystallization have occurred during fossilization. Traditional analyses, such as optical microscopy inspection and cathodoluminescence, have proven not to be enough to understand the taphonomic story of some eggshells. Recently, electron backscatter diffraction has been used, in combination with other techniques, to better understand the alteration of fossil eggshells. Here we present a combined study using scanning electron microscopy, optical microscopy, cathodoluminescence and electron backscatter diffraction of eggshell fragments assigned to Megaloolithus cf. siruguei from the Upper Cretaceous outcrops of the Cameros Basin. We focus our study on the presence of secondary shell units that mimic most aspects of the ultrastructure of the eggshell mammillae, but grow far from the inner surface of the eggshell. We call these structures extra-spherulites, describe their crystal structure and demonstrate their secondary origin. Our study has important implications for the interpretation of secondary shell units as biological or pathological structures. Thus, electron backscatter diffraction complements other microscope techniques as a useful tool for understanding taphonomical alterations in fossil eggshells.

  7. Residence, resorption and recycling of zircons in Devils Kitchen rhyolite, Coso Volcanic Field, California

    Science.gov (United States)

    Miller, J.S.; Wooden, J.L.

    2004-01-01

    Zircons from the Devils Kitchen rhyolite in the Pleistocene Coso Volcanic field, California have been analyzed by in situ Pb/U ion microprobe (SHRIMP-RG) and by detailed cathodoluminescence imaging. The zircons yield common-Pb-corrected and disequilibrium-corrected 206Pb/238U ages that predate a previously reported K-Ar sanidine age by up to 200 kyr, and the range of ages exhibited by the zircons is also approximately 200 kyr. Cathodoluminescence imaging indicates that zircons formed in contrasting environments. Most zircons are euhedral, and a majority of the zircons are weakly zoned, but many also have anhedral, embayed cores, with euhedral overgrowths and multiple internal surfaces that are truncated by later crystal zones. Concentrations of U and Th vary by two orders of magnitude within the zircon population, and by 10-20 times between zones within some zircon crystals, indicating that zircons were transferred between contrasting chemical environments. A zircon saturation temperature of ???750??C overlaps within error a previously reported phenocryst equilibration temperature of 740 ?? 25??C. Textures in zircons indicative of repeated dissolution and subsequent regrowth are probably caused by punctuated heating by mafic magma input into rhyolite. The overall span of ages and large variation in U and Th concentrations, combined with calculated zircon saturation temperatures and resorption times, are most compatible with crystallization in magma bodies that were emplaced piecemeal in the crust at Coso over 200 kyr prior to eruption, and that were periodically rejuvenated or melted by subsequent basaltic injections. ?? Oxford University Press 2004; all rights reserved.

  8. Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells

    Science.gov (United States)

    Bauluz, Blanca; Canudo, José Ignacio; Gasca, José Manuel; Torcida Fernández-Baldor, Fidel

    2016-01-01

    Abnormalities in the histo- and ultrastructure of the amniote eggshell are often related to diverse factors, such as ambient stress during egg formation, pathologies altering the physiology of the egg-laying females, or evolutionarily selected modifications of the eggshell structure that vary the physical properties of the egg, for example increasing its strength so as to avoid fracture during incubation. When dealing with fossil materials, all the above hypotheses are plausible, but a detailed taphonomical study has to be performed to rule out the possibility that secondary processes of recrystallization have occurred during fossilization. Traditional analyses, such as optical microscopy inspection and cathodoluminescence, have proven not to be enough to understand the taphonomic story of some eggshells. Recently, electron backscatter diffraction has been used, in combination with other techniques, to better understand the alteration of fossil eggshells. Here we present a combined study using scanning electron microscopy, optical microscopy, cathodoluminescence and electron backscatter diffraction of eggshell fragments assigned to Megaloolithus cf. siruguei from the Upper Cretaceous outcrops of the Cameros Basin. We focus our study on the presence of secondary shell units that mimic most aspects of the ultrastructure of the eggshell mammillae, but grow far from the inner surface of the eggshell. We call these structures extra-spherulites, describe their crystal structure and demonstrate their secondary origin. Our study has important implications for the interpretation of secondary shell units as biological or pathological structures. Thus, electron backscatter diffraction complements other microscope techniques as a useful tool for understanding taphonomical alterations in fossil eggshells. PMID:27144767

  9. Fluid-rock reactions in an evaporitic melange, Permian Haselgebirge, Austrian Alps

    Science.gov (United States)

    Spotl, C.; Longstaffe, F.J.; Ramseyer, K.; Kunk, M.J.; Wiesheu, R.

    1998-01-01

    Tectonically isolated blocks of carbonate rocks present within the anhydritic Haselgebirge melange of the Northern Calcareous Alps record a complex history of deformation and associated deep-burial diagenetic to very low-grade metamorphic reactions. Fluids were hot (up to ~ 250 ??C) and reducing brines charged with carbon dioxide. Individual carbonate outcrops within the melange record different regimes of brine-rock reactions, ranging from pervasive dolomite recrystallization to dedolomitization. Early diagenetic features in these carbonates were almost entirely obliterated. Matrix dolomite alteration was related to thermochemical sulphate reduction (TSR) recognized by the replacement of anhydrite by calcite + pyrite ?? native sulphur. Pyrite associated with TSR is coarsely crystalline and characterized by a small sulphur isotope fractionation relative to the precursor Permian anhydrite. Carbonates associated with TSR show low Fe/Mn ratios reflecting rapid reaction of ferrous iron during sulphide precipitation. As a result, TSR-related dolomite and calcite typically show bright Mn(II)-activated cathodoluminescence in contrast to the dull cathodoluminescence of many (ferroan) carbonate cements in other deep-burial settings. In addition to carbonates and sulphides, silicates formed closely related to TSR, including quartz, K-feldspar, albite and K-mica. 40Ar/39Ar analysis of authigenic K-feldspar yielded mostly disturbed step-heating spectra which suggest variable cooling through the argon retention interval for microcline during the Late Jurassic. This timing coincides with the recently recognized subduction and closure of the Meliata-Hallstatt ocean to the south of the Northern Calcareous Alps and strongly suggests that the observed deep-burial fluid-rock reactions were related to Jurassic deformation and melange formation of these Permian evaporites.

  10. Characteristics of the crystalline and luminescence properties of a-plane GaN films grown on γ-LiA102(302)substrates

    Institute of Scientific and Technical Information of China (English)

    Tingting Jia; Ke Xu; Shengming Zhou; Hui Lin; Hao Teng; Xiaorui Hou; Jianqi Liu; Jun Huang; Min Zhang; Jianfeng Wang

    2011-01-01

    A-plane GaN films are deposited on (302) 7-LiAlC>2 substrates by metalorganic chemical vapor deposition (MOCVD). The X-ray diffraction (XRD) results indicate that the in-plane orientation relationship between GaN and LAO substrates is [010]Lao/[0001]GaN and [203]LAO//[1100]GaN with 0.03% and 2.85% lattice mismatch, respectively. Raman scattering results indicate that the strain in the films decreases along with the increase in the thickness of the films. In addition to the band edge emission at 3.42 eV, defects-related luminescence at 3.35 eV is observed in the photoluminescence (PL) spectra. The cathodoluminescence (CL) spectra indicate that the 3.35-eV emission is related to the V pits.%@@ A-plane GaN films are deposited on(302)γ-LiA102 substrates by metalorganic chemical vapor deposition (MOCVD).The X-ray diffraction(XRD)results indicate that the in-plane orientation relationship between GaN and LAO substrates is [010]LAO//[0001]GaN and [203]LAO//[1100]GaN with 0.03% and 2.85% lattice mismatch,respectively.Raman scattering results indicate that the strain in the films decreases along with the increase in the thickness of the films.In addition to the band edge emission at 3.42 eV,defects-related luminescence at 3.35 eV is observed in the photoluminescence(PL)spectra.The cathodoluminescence (CL)spectra indicate that the 3.35-eV emission is related to the V pits.

  11. Fission products in shell of the freshwater bivalve Dreissena polymorpha

    Energy Technology Data Exchange (ETDEWEB)

    Zuykov, M.A.; Orlova, M.I.; Burakov, B.E.; Zamoryanskaya, M.V.; Anderson, E.B. [V.G.Khlopin Radium Institute, Lab. of Applied Mineralogy and Radiogeochemistry, Saint Petersburg (Russian Federation)

    2004-07-01

    Within activity of Bio-mineralogical group of KRI (RFBR no. 03-05-65195), dealing with distribution, accumulation and relations of radionuclides within shells of freshwater molluscs, a capacity to incorporating of {sup 137}Cs, {sup 85}Sr and {sup 241}Am into shells of Dreissena polymorpha, obtained after laboratory experiments was studied; and a distribution of Americium-241 in shell is preliminary discussed on the basis a cathodoluminescence (CL). Short-term uptake experiments were performed to understand difference in accumulation of radionuclides (Cs, Sr, Am) in high concentration which were added in the experimental solutions separately as well as in mixtures by molluscs. The data obtained suggest greater content of {sup 85}Sr than {sup 137}Cs and {sup 241}Am in all studied samples, thus the mixture of radionuclides had no effect on greater accumulation of Sr by the molluscs shell. The concentration of radionuclides in shells are following (in Bq/g): {sup 85}Sr - 5x10{sup 4}; {sup 137}Cs 1x10{sup 4}; {sup 241}Am 2x10{sup 4} (with maximum 1x10{sup 5}). Present data suggest also on high capacity for incorporating of these radionuclides in molluscs shells in laboratory conditions. The cathodoluminescent images on full section of Am-doped shells (containing about 0.00005 wt.% of Am) of D.polymorpha along a length of valve was characterized by light bands of blue-green color which are parallel to the shell surface and corresponded to different shell layers. Maximum intensity is corresponds to the layer boundaries characterised by concentration of organic component. However, this result should be treated with care due to the large uncertainty in the determination of the americium in organic and mineral components of mollusc shells separately, which is a subject of further investigations. (author)

  12. Mineralogical characterization of diamonds from Roosevelt Indigenous Reserve, Brazil, using non-destructive methods

    Science.gov (United States)

    Borges, M. P. A. C.; Moura, M. A.; Lenharo, S. L. R.; Smith, C. B.; Araujo, D. P.

    2016-11-01

    In this study, 660 diamonds from Igarapé Lajes Diggings (Roosevelt and Aripuanã Park indigenous areas), in Amazonian craton, Rondônia State, Brazil, were investigated. Their morphological, optical and surface characteristics were described using optical and scanning electron microscopy (SEM), cathodoluminescence (CL) and infrared spectroscopy (FTIR). The results demonstrated a predominance of resorbed crystals with many surface corrosion features, generally colorless, and led to the identification of four distinct groups: G1, G2, G3 and G4. Group G1 presents features of secondary sources while G2 and G4 show only primary features, some of which are not described in literature. Group G3 is similar to the other groups, however, is composed of less resorbed specimens with primary octahedral morphology relatively well preserved, indicating shorter time of exposure to dissolution effects. Cathodoluminescence in G2 is attributed to features of plastic deformation and to low contents of nitrogen (< 100 ppm, Type II) and high aggregation (IaB). G4 shows homogeneous blue CL, high contents of nitrogen (700 to 1000 ppm) and intermediate aggregation (IaAB). G1 presents luminescence influenced by radiation effects and populations with N contents and aggregation in the same ranges of G2 and G4, suggesting that the primary sources of the three groups can be the same. The relationship of nitrogen content versus aggregation state indicates higher temperatures of formation for G2 and lower for G4. The obtained data suggests that diamonds of G2 originated in sublithospheric mantle as has also been reported in nearby deposits (Machado River and Juína). The employed techniques were also effective in distinguishing diamonds from Roosevelt Reserve and from other localities, indicating that they could be used for improvement of certification procedures of diamonds of unknown origin.

  13. Influence of the spray pyrolysis seeding and growth parameters on the structure and optical properties of ZnO nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Juan, E-mail: jrodriguez@uni.edu.pe [Facultad de Ciencias, Universidad Nacional de Ingeniería, P.O. Box 31-139, Lima 31 (Peru); Feuillet, Guy [CEA Grenoble/LETI, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Donatini, Fabrice [Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Onna, Diego [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); Sanchez, Luis [Facultad de Ciencias, Universidad Nacional de Ingeniería, P.O. Box 31-139, Lima 31 (Peru); Candal, Roberto [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); ECyT, 3iA, Universidad Nacional de San Martín, Martín de Irigoyen N° 3100 (1650), San Martín, Pcia de Buenos Aires (Argentina); Marchi, M. Claudia [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); CMA, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. I, 1428 Buenos Aires (Argentina); Bilmes, Sara A. [DQIAQF-INQUIMAE, FCEyN-Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, 1428 Buenos Aires (Argentina); Chandezon, Frédéric [University Grenoble Alpes, INAC-SPRAM, F-38000 Grenoble (France); CNRS, INAC-SPRAM, F-38000 Grenoble (France); CEA, INAC-SPRAM, F-38000 Grenoble (France)

    2015-02-01

    ZnO nanorods (NRs) were grown on fluorine doped tin oxide (FTO) substrates at low temperatures (90 °C) from Zn{sup 2+} precursors in alkaline media previously seeded with ZnO nanoparticles. These were deposited onto the FTO substrate heated at 350 °C by spray pyrolysis of a Zn acetate solution in a water ethanol mixture. The structure of seeds was tuned by the ethanol to water ratio, Γ, which controls the solvent evaporation rate of drops impinging the substrate. From a detailed characterization using a combination of scanning electron microscopy, X-ray diffraction, UV–visible absorption and cathodoluminescence spectroscopies, the dependence of the morphology and optical properties of the ZnO NRs on the seeding conditions was demonstrated. NRs grown on seeds deposited from solutions with Γ in the 0.03–0.06 range – i.e. when the surface excess of ethanol in the water–ethanol mixture has a maximum – show thinner average diameters and stacking faults due to the presence of zinc blende domains embedded into an overall wurtzite NR. They furthermore exhibit blue-shifted near band edge emission peak and a high deep level emission in cathodoluminescence. All these findings support the use of spray pyrolysis as a simple and reproducible way to control the seeds deposition, influencing the growth, the structure and the optical properties of the final ZnO NRs. - Highlights: • ZnO pyrolytic seeds tuned by the rate of solvent evaporation. • ZnO NRs grown from tuned pyrolytic seed's structure shows diameter dependence. • ZnO NRs show stacking faults due to the presence of zinc blende domains.

  14. Interface Trap Density Reduction for Al2O3/GaN (0001) Interfaces by Oxidizing Surface Preparation prior to Atomic Layer Deposition.

    Science.gov (United States)

    Zhernokletov, Dmitry M; Negara, Muhammad A; Long, Rathnait D; Aloni, Shaul; Nordlund, Dennis; McIntyre, Paul C

    2015-06-17

    We correlate interfacial defect state densities with the chemical composition of the Al2O3/GaN interface in metal-oxide-semiconductor (MOS) structures using synchrotron photoelectron emission spectroscopy (PES), cathodoluminescence and high-temperature capacitance-voltage measurements. The influence of the wet chemical pretreatments involving (1) HCl+HF etching or (2) NH4OH(aq) exposure prior to atomic layer deposition (ALD) of Al2O3 were investigated on n-type GaN (0001) substrates. Prior to ALD, PES analysis of the NH4OH(aq) treated surface shows a greater Ga2O3 component compared to either HCl+HF treated or as-received surfaces. The lowest surface concentration of oxygen species is detected on the acid etched surface, whereas the NH4OH treated sample reveals the lowest carbon surface concentration. Both surface pretreatments improve electrical characteristics of MOS capacitors compared to untreated samples by reducing the Al2O3/GaN interface state density. The lowest interfacial trap density at energies in the upper band gap is detected for samples pretreated with NH4OH. These results are consistent with cathodoluminescence data indicating that the NH4OH treated samples show the strongest band edge emission compared to as-received and acid etched samples. PES results indicate that the combination of reduced carbon contamination while maintaining a Ga2O3 interfacial layer by NH4OH(aq) exposure prior to ALD results in fewer interface traps after Al2O3 deposition on the GaN substrate.

  15. gram-scale metafluids and large area tunable metamaterials: design, fabrication, and nano-optical tomographic characterization (Conference Presentation)

    Science.gov (United States)

    Dionne, Jennifer A.

    2016-09-01

    Advances in metamaterials and metasurfaces have enabled unprecedented control of light-matter interactions. Metamaterial constituents support high-frequency electric and magnetic dipoles, which can be used as building blocks for new materials capable of negative refraction, electromagnetic cloaking, strong visible-frequency circular dichroism, and enhanced magnetic or chiral transitions in ions and molecules. However, most metamaterials to date have been limited to solid-state, static, narrow-band, and/or small-area structures. Here, we introduce the design, fabrication, and three-dimensional nano-optical characterization of large-area, dynamically-tunable metamaterials and gram-scale metafluids. First, we use transformation optics to design a broadband metamaterial constituent - a metallo-dielectric nanocrescent - characterized by degenerate electric and magnetic dipoles. A periodic array of nanocrescents exhibits large positive and negative refractive indices at optical frequencies, confirmed through simulations of plane wave refraction through a metamaterial prism. Simulations also reveal that the metamaterial optical properties are largely insensitive to the wavelength, orientation and polarization of incident light. Then, we introduce a new tomographic technique, cathodoluminescence (CL) spectroscopic tomography, to probe light-matter interactions in individual nanocrescents with nanometer-scale resolution. Two-dimensional CL maps of the three-dimensional nanostructure are obtained at various orientations, while a filtered back projection is used to reconstruct the CL intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. Finally, we demonstrate the fabrication of dynamically tunable large-area metamaterials and gram-scale metafluids, using a

  16. Electron beam pumped III-V nitride vertical cavity surface emitting lasers grown by molecular beam epitaxy

    Science.gov (United States)

    Ng, Hock Min

    The design and fabrication by molecular beam epitaxy of a prototype vertical cavity laser based on the III-V nitrides were investigated in this work. The bottom mirror of the laser consists of distributed Bragg reflectors (DBRs) based on quarterwave AlN (or AlxGa1-xN) and GaN layers. Such DBRs were designed for maximum reflectivity in the spectral region from 390--600 nm. The epitaxial growth of these two binaries on each other revealed that while AlN grows on GaN in a two-dimensional mode (Frank-van der Merwe mode), GaN grows on AlN in a three-dimensional mode (Stranski-Krastanov mode). In spite of that, DBRs with peak reflectance up to 99% and bandwidths of 45nm were fabricated. The measured reflectance spectra were compared with simulations using the transmission matrix method. The mechanical stability of these DBR structures due to non-uniform distribution of strain arising from lattice or thermal mismatch of the various components were also addressed. The active region of the laser consists of InGaN/GaN multiple quantum wells (MQWs). The existence of up to the third order diffraction peaks in the x-ray diffraction spectra suggests that the interfaces between InGaN and GaN are sharp with little interdiffusion at the growth temperature. The photoluminescence and cathodoluminescence spectra were analyzed to determine the optical quality of the MQWs. The best MQWs were shown to have a single emission peak at 397nm with full width half maximum (FWHM) of 11nm. Cathodoluminescence studies showed that there are spatially localized areas of intense light emission. The complete device was formed on (0001) sapphire substrates using the previously described DBRs as bottom mirrors and the MQWs as the active region. The top mirror of the device consists of metallic silver. The device was pumped by an electron beam from the top mirror side and the light output was collected from the sapphire side. Measurements at 100K showed narrowing of the linewidth with increasing pump

  17. Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

    Science.gov (United States)

    Conroy, M.; Li, H.; Kusch, G.; Zhao, C.; Ooi, B.; Edwards, P. R.; Martin, R. W.; Holmes, J. D.; Parbrook, P. J.

    2016-05-01

    We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips' broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD's confinement dimensions, rather than significantly increasing the In%. This article details the easily controlled method of manipulating the QDs dimensions producing high crystal quality InGaN without complicated growth conditions needed for strain relaxation and alloy compositional changes seen for bulk planar GaN templates.We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips' broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD

  18. Diagenesis of echinoderm skeletons: Constraints on paleoseawater Mg/Ca reconstructions

    Science.gov (United States)

    Gorzelak, Przemysław; Krzykawski, Tomasz; Stolarski, Jarosław

    2016-09-01

    One of the most profound environmental changes thought to be reflected in chemical composition of numerous geological archives is Mg/Ca ratio of the seawater, which has varied dramatically throughout the Phanerozoic. Echinoderms that today typically form high magnesium calcite skeletons are increasingly being utilized as a proxy for interpreting secular changes in seawater chemistry. However, accurate characterization of the diagenetic changes of their metastable high magnesium calcite skeletons is a prerequisite for assessing their original, major-element geochemical composition. Here we expand the existing models of diagenesis of echinoderm skeleton by integration of various analytical methods that up to now rarely have been used to assess the diagenetic changes of fossil echinoderms. We validated the preservation of a suite of differently preserved echinoderm ossicles, mostly crinoids, ranging in age from the Cambrian through Recent. In 13 of 99 fossil echinoderm ossicles we found well-preserved porous microstructure (stereom), non-luminescent behaviour or blotchy dark color in cathodoluminescence, and distinct nanostructural features (layered and nanocomposite structure). Moreover, in representatives of such preserved samples, distribution of sulphates associated with organic matter is identical to those in Recent echinoderms. Only such ossicles, despite of local micrometer-scale diagenetic changes, were herein considered well-preserved, retaining their original major-element skeletal composition. By contrast, majority of samples show transformation to the stable low magnesium calcite that leads to obliteration of the primary geochemical and micro/nanostructural features and is accompanied with increase in cathodoluminescence emission intensity. Using only well-preserved fossil echinoderm samples, we found purely random variation in Mg/Ca in echinoderm skeletons through the observed time series; any periodicities in echinoderm skeletal Mg/Ca ratio which might

  19. Zoned chondrules in Semarkona: Evidence for high-and low-temperature processing

    Science.gov (United States)

    Grossman, J.N.; Alexander, C.M. O'D.; Wang, Jingyuan; Brearley, A.J.

    2002-01-01

    At least 15% of the low-FeO chondrules in Semarkona (LL3.0) have mesostases that are concentrically zoned in Na, with enrichments near the outer margins. We have studied zoned chondrules using electron microprobe methods (x-ray mapping plus quantitative analysis), ion micropobe analysis for trace elements and hydrogen isotopes, cathodoluminescence imaging, and transmission electron microscopy in order to determine what these objects can tell us about the environment in which chondrules formed and evolved. Mesostases in these chondrules are strongly zoned in all moderately volatile elements and H (interpreted as water). Calcium is depleted in areas of volatile enrichment. Titanium and Cr generally decrease toward the chondrule surfaces, whereas Al and Si may either increase or decrease, generally in opposite directions to one another; Mn follows Na in some chondrules but not in others; Fe and Mg are unzoned. D/H ratios increase in the water-rich areas of zoned chondrules. Mesostasis shows cathodoluminescence zoning in most zoned chondrules, with the brightest yellow color near the outside. Mesostasis in zoned chondrules appears to be glassy, with no evidence for devitrification. Systematic variations in zoning patterns among pyroxene- and olivine-rich chondrules may indicate that fractionation of low- and high-Ca pyroxene played some role in Ti, Cr, Mn, Si, Al, and some Ca zoning. But direct condensation of elements into hot chondrules, secondary melting of late condensates into the outer portions of chondrules, and subsolidus diffusion of elements into warm chondrules cannot account for the sub-parallel zoning profiles of many elements, the presence of H2O, or elemental abundance patterns. Zoning of moderately volatile elements and Ca may have been produced by hydration of chondrule glass without devitrification during aqueous alteration on the parent asteroid. This could have induced structural changes in the glass allowing rapid diffusion and exchange of elements

  20. Optical investigations on the wide bandgap semiconductors diamond and aluminum nitride

    Energy Technology Data Exchange (ETDEWEB)

    Teofilov, Nikolai

    2007-07-01

    In the context of this thesis, new results about optical defects and intrinsic properties of diamond, AlN and AlGaN alloys have been obtained. The main experimental techniques used were low temperature cathodoluminescence and photoluminescence spectroscopy. First, different aspects of intentional and background doping of diamond were discussed. Thus, the most commonly observed green luminescence emission from boron doped HPHT diamonds has been studied by means of temperature dependent CL in a wide temperature range from 10 K to 450 K. One further subject, addressing deep defect nitrogen related luminescence was a study of nitrogen addition in combustion flame grown CVD diamond layers. Two further topics concern intrinsic excitations in diamond, free excitons and electron-hole drops. Several important parameters like the critical density, the critical temperature, and the low-temperature density inside the drops were evaluated. The ground state density of the electron-hole condensate in diamond is about {approx} 42 times larger than that in Si, and the critical temperature takes very high values in the range of 165K.. 173K. Cathodoluminescence investigations on epitaxial wurtzite AlN layers grown on sapphire, SiC, and Si substrates, have shown that although the material is generally of good optical quality, deep level luminescence are still dominating the spectra. Relatively sharp near-band-edge transitions have been observed in all three samples that exhibit significantly reduced line widths for the AlN/sapphire and the AlN/SiC samples. Much broader emission lines in the near band-gap region have been observed for the first time from the AlN sample grown on Si (111) substrate. Temperature dependent CL measurements and numerical line decompositions reveal complicated substructures in the excitonic lines. The temperature dependence of the energy positions and broadening parameters of the transition have been studied and compared with the other materials. Epitaxial Al

  1. Synthesis and Luminescent Properties of Planar-tip and Tapered-tip ZnO Nanorod Arrays

    Institute of Scientific and Technical Information of China (English)

    Chun-wen WANG; Jr-hau HE; Lih-juann CHEN

    2008-01-01

    Vertically aligned ZnO nanorods were synthesized on a-plane sapphire via a metal catalyzed vapor phase transport and condensation process in a two-zone vacuum furnace. Planar-tip and tapered-tip ZnO nanorods were successfully synthesized by utilizing different source materials under the same growth conditions. The growth mechanisms were proposed to be vapor-liquid-solid (VLS) process for planar-tip ZnO nanorods and a combination of VLS and self-catalyzed processes for tapered-tip ZnO nanorods. From cathodoluminescence (CL) measurements, tapered-tip ZnO nanorods have more intense green emission than planar-tip ZnO nanorods, and therefore possess higher oxygen vacancy concentration than planar-tip ZnO nanorods. From CL characteristics, well-aligned planar-tip ZnO nanorods shall serve effectively as laser source, while well-aligned tapered-tip ZnO nanorods are suitable for direction-related optical applications.

  2. The influence of substrate temperature on the structural and luminescent properties of as-deposited SrGa{sub 2}S{sub 4}:Ce{sup 3+} thin films coated with a TaSi{sub 2} thin layer

    Energy Technology Data Exchange (ETDEWEB)

    Moleme, P.A.; Swart, H.C.; Kumar, Vinod; Terblans, J.J. [University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa)

    2016-03-15

    SrGa{sub 2}S{sub 4}:Ce{sup 3+} thin films coated with a very thin layer of TaSi{sub 2} were deposited on Si(100) substrates utilizing the pulsed laser deposition system. During the ablation of the targets for thin films preparation, the Si(100) substrate temperature varied in the range of 400-600 C. The as-deposited SrGa{sub 2}S{sub 4}:Ce{sup 3+} films showed an orthorhombic crystal structure, and the TaSi{sub 2} coating layer showed a hexagonal structure. The films maintained the crystal structures within the temperature ranges of 400-600 C. The distribution of particles with irregular sizes contributing to a difference in surface roughness of the as-prepared thin films was observed by atomic force microscopy. The films showed a broad photoluminescence (PL) peak at 416 nm, and the maximum PL intensity, as compared to other films, was observed for a film deposited at a substrate temperature of 450 C. Two broad cathodoluminescence peaks (440 and 490 nm) due to Ce{sup 3+} emission were observed for a film deposited at a substrate temperature of 450 C. The presence of the TaSi{sub 2} coating layer on the SrGa{sub 2}S{sub 4}:Ce{sup 3+} thin films was confirmed with Auger electron spectroscopy surface elemental analysis, and Auger depth profiles showed uniform concentrations of the main elements in the deposited films. (orig.)

  3. Effect of the H2 plasma treatment of a seed layer on the synthesis of ZnO nanorods using a microwave hydrothermal method

    Science.gov (United States)

    Koo, Horng-Show; Lin, Ching-Cheng; Chen, Yao-Ju; Peng, Cheng-Hsiung; Chen, Mi

    2014-01-01

    The effect of H2 plasma treatment of a seed layer on the synthesis and characterization of zinc oxide (ZnO) nanorods is determined. Using an Al-doped ZnO (AZO) thin film as a seed layer, well-aligned ZnO nanorods are rapidly grown on an indium tin oxide (ITO)-coated glass substrate using a microwave hydrothermal method. The deposited AZO substrate was previously treated with H2 plasma. The effect of H2 plasma treatment of the seed layer on the alignment, growth rate, and crystallinity of the ZnO nanorods is determined. It is shown that the alignment and growth rate of the ZnO nanorods depend on the characteristics and roughness of the seed layer, which are improved by H2 plasma treatment. Various characterization methods such as X-ray diffraction (XRD), cathodoluminescence (CL), transmission electron microscopy (TEM), and X-ray photoemission spectroscopy (XPS) are used to determine the characteristic quality of the ZnO nanorods. A fundamental model of the effect of H2 plasma treatment on the seed layer and ZnO growth using a microwave hydrothermal process is also presented.

  4. Defect creation via dissociative recombination of ionic centers in solid Ne matrices

    Energy Technology Data Exchange (ETDEWEB)

    Savchenko, E.V.; Khyzhniy, I.V.; Uyutnov, S.A.; Bludov, M.A. [Institute for Low Temperature Physics and Engineering NASU, 61103 Kharkov (Ukraine); Gumenchuk, G.B.; Bondybey, V.E. [Lehrstuhl für Physikalische Chemie II TUM, 85747 Garching (Germany)

    2016-05-01

    Recombination of the intrinsic ionic centers Ne{sub 2}{sup +} (self-trapped holes) with the detrapped electrons in solid Ne matrices and relaxation channels have been studied. The experiments were performed employing combination of the cathodoluminescence (CL) with current and optical activation spectroscopy techniques. CL spectra were recorded simultaneously in the VUV and visible range. Yields of spectrally resolved thermally and photon-stimulated luminescence (TSL, PSL) and thermally and photon-stimulated exoelectron emission (TSEE, PSEE) were measured in the time-correlated manner. It was found that the recombination reaction proceeds with irreversible dissociation of the transient Ne{sub 2}{sup ∗∗} centers and the dissociative recombination (DR) products exit the matrix cage. Products of the DR reaction are found to be in 3s and 3p states. The detection of “defect” components in the TSL and PSL points to the defect formation via DR in Ne matrices. The temperature range of the electron traps stability is elucidated. A long-lasting “afteremission” of electrons and afterglow of VUV photons observed on switching off the irradiation suggest the accumulation of the uncompensated negative charge.

  5. Origin of zoning within dedolomite and calcitized gypsum of the Mississippian Arroyo Penasco Group

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, D.S.

    1985-01-01

    The Mississippian Arroyo Penasco Group carbonates are the oldest Paleozoic rocks present in north-central New Mexico. These supratidal to shallow,subtidal sediments exhibit complex diagenetic fabrics produced by periods of pre-Pennsylvanian subaerial exposure. Both extensive recrystallization of the Espiritu Santo carbonates and brecciation of the overlying Macho Member of the Tererro Formation resulted from an extended period of Mississippian subaerial exposure of broad, low-relief tidal flats. Cathodoluminescent petrography indicates that the recrystallized limestones consist of calcite pseudomorphs of dolomite and gypsum. Dedolomite and calcitized gypsum crystals, with /sup 13/C//sup 12/C ratios of -2 to +1.5% PDB, range from highly zoned to uniformly luminescent. Electron microprobe analyses reveals variable Mn and Fe contents across the pseudomorphs which are responsible for differences in observed luminosity. These features are interpreted to reflect a period of subaerial exposure after deposition of Macho Member sediments, which caused dissolution of gypsum and dolomite by sulfate and Mg depleted meteoric fluids and produced the collapse breccia. Preservation of zoning within some pseudomorphs required simultaneous dissolution of gypsum and dolomite and precipitation of calcite. C-isotope data indicates a meteoric to mixed phreatic origin for pore fluids which precipitated calcite; repetitive zoning within dolomite and gypsum pseudomorphs is indicative of interactions between marine and meteoric phreatic fluids in the intertidal environment.

  6. Controlled preparation of aluminum borate powders for the development of defect-related phosphors for warm white LED lighting

    Science.gov (United States)

    Guimarães, Vinicius F.; Salaün, Mathieu; Burner, Pauline; Maia, Lauro J. Q.; Ferrier, Alban; Viana, Bruno; Gautier-Luneau, Isabelle; Ibanez, Alain

    2017-03-01

    The optimization of the elaboration conditions of a new family of highly emissive white phosphors based on glassy yttrium aluminum borates (g-YAB) compositions is presented. Their preparation from solutions is based on the polymeric precursor method (modified Pechini process), involving non-toxic and low cost precursors. The resulting resins were first dried at moderate temperatures followed by two-step annealing treatments of the obtain powders under controlled atmospheres: a first pyrolysis under nitrogen followed by a calcination under oxygen. This favored the gradual oxidation of organic moieties coming from starting materials, avoiding uncontrolled self-combustion reactions, which generate localized hot spots. This prevented phase segregations and the formation of pyrolytic carbon or carbonates, which are strongly detrimental to the luminescence properties. Thus, coupled chemical analyses and luminescence characterizations showed the high chemical homogeneity of the resulting powders and their intense emissions in the whole visible range. These emissions can be tuned from blue to warm white by adjusting the calcination temperature that is an important advantage for the development of LED devices. We showed that impurities of monovalent and divalent cations act as quenching emission centers for these phosphors. Therefore, by increasing the purity grade, we significantly enhanced the PL emissions leading to high internal quantum yields (80-90%). Finally, cathodoluminescence emissions showed the homogeneous dispersion of emitting centers in the g-YAB matrix.

  7. Position-controlled MOVPE growth and electro-optical characterization of core-shell InGaN/GaN microrod LEDs

    Science.gov (United States)

    Schimpke, Tilman; Lugauer, H.-J.; Avramescu, A.; Varghese, T.; Koller, A.; Hartmann, J.; Ledig, J.; Waag, A.; Strassburg, M.

    2016-03-01

    Today's InGaN-based white LEDs still suffer from a significant efficiency reduction at elevated current densities, the so-called "Droop". Core-shell microrods, with quantum wells (QWs) covering their entire surface, enable a tremendous increase in active area scaling with the rod's aspect ratio. Enlarging the active area on a given footprint area is a viable and cost effective route to mitigate the droop by effectively reducing the local current density. Microrods were grown in a large volume metal-organic vapor phase epitaxy (MOVPE) reactor on GaN-on-sapphire substrates with a thin, patterned SiO2 mask for position control. Out of the mask openings, pencil-shaped n-doped GaN microrod cores were grown under conditions favoring 3D growth. In a second growth step, these cores are covered with a shell containing a quantum well and a p-n junction to form LED structures. The emission from the QWs on the different facets was studied using resonant temperature-dependent photoluminescence (PL) and cathodoluminescence (CL) measurements. The crystal quality of the structures was investigated by transmission electron microscopy (TEM) showing the absence of extended defects like threading dislocations in the 3D core. In order to fabricate LED chips, dedicated processes were developed to accommodate for the special requirements of the 3D geometry. The electrical and optical properties of ensembles of tens of thousands microrods connected in parallel are discussed.

  8. Hybrid fluorescence and electron cryo-microscopy for simultaneous electron and photon imaging.

    Science.gov (United States)

    Iijima, Hirofumi; Fukuda, Yoshiyuki; Arai, Yoshihiro; Terakawa, Susumu; Yamamoto, Naoki; Nagayama, Kuniaki

    2014-01-01

    Integration of fluorescence light and transmission electron microscopy into the same device would represent an important advance in correlative microscopy, which traditionally involves two separate microscopes for imaging. To achieve such integration, the primary technical challenge that must be solved regards how to arrange two objective lenses used for light and electron microscopy in such a manner that they can properly focus on a single specimen. To address this issue, both lateral displacement of the specimen between two lenses and specimen rotation have been proposed. Such movement of the specimen allows sequential collection of two kinds of microscopic images of a single target, but prevents simultaneous imaging. This shortcoming has been made up by using a simple optical device, a reflection mirror. Here, we present an approach toward the versatile integration of fluorescence and electron microscopy for simultaneous imaging. The potential of simultaneous hybrid microscopy was demonstrated by fluorescence and electron sequential imaging of a fluorescent protein expressed in cells and cathodoluminescence imaging of fluorescent beads.

  9. Stress dependence of optically active diamagnetic point defects in silicon oxynitride.

    Science.gov (United States)

    Pezzotti, Giuseppe; Hosokawa, Koichiro; Munisso, Maria Chiara; Leto, Andrea; Zhu, Wenliang

    2007-08-30

    The cathodoluminescence (CL) spectrum arising from diamagnetic point defects of silicon oxynitride lattice was analyzed to extract quantitative information on local stress fields stored on the surface of a silicon nitride polycrystal. A calibration procedure was preliminarily made to obtain a relationship between CL spectral shift and applied stress, according to the piezo-spectroscopic effect. In this calibration procedure, we used the uniaxial stress field developed in a rectangular bar loaded in a four-point flexural jig. Stress dependence was clearly detected for the most intense spectral band of a doublet arising from diamagnetic ([triple bond]Si-Si[triple bond]) defects, which was located at around 340 nm. The shallow nature of the electron probe enabled the characterization of surface stress fields with sub-micrometer-order spatial resolution. As applications of the PS technique, the CL emission from [triple bond]Si-Si[triple bond] defects was used as a stress probe for visualizing the residual stress fields stored at grain-boundary regions and at the tip of a surface crack propagated in polycrystalline silicon nitride.

  10. Aqueous solution route to high-aspect-ratio zinc oxide nanostructures on indium tin oxide substrates.

    Science.gov (United States)

    Ku, Chen-Hao; Wu, Jih-Jen

    2006-07-06

    High-aspect-ratio ZnO nanowires and nanotubes are formed on indium tin oxide (ITO) substrates using a three-step route at low temperatures. The three steps, including successive ionic layer absorption and reaction (SILAR) deposition of the ZnO seed layer, hydrothermal annealing of the seed layer, and chemical bath deposition (CBD) of the one-dimensional (1D) ZnO nanostructures, are all conducted in aqueous solutions at temperatures below 120 degrees C. Both the hydrothermal annealing of the SILAR seed layer and the low-concentration precursor solution employed in the CBD process are crucial in order to synthesize the uniform and high-aspect-ratio ZnO nanostructures on the ITO substrate. TEM analyses reveal that both the nanowire and the nanotube possess the single-crystal structure and are grown along [001] direction. Room-temperature cathodoluminescence spectrum of the 1D ZnO nanostructures shows a sharp ultraviolet emission at 375 nm and a broad green-band emission.

  11. Forensic Scanning Electron Microscope

    Science.gov (United States)

    Keeley, R. H.

    1983-03-01

    The scanning electron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanning electron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

  12. Facile synthesis of Bi/BiOCl composite with selective photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dongling; Zhang, Min; Lu, Qiuju; Chen, Junfang [Research Institute for New Material Technology, Department of Research Center for Materials Interdisciplinary Science, Chongqing University of Arts and Science, Chongqing 402160 (China); Liu, Bitao, E-mail: liubitao007@163.com [Research Institute for New Material Technology, Department of Research Center for Materials Interdisciplinary Science, Chongqing University of Arts and Science, Chongqing 402160 (China); Wang, Zhaofeng, E-mail: zhaofeng.wang@uconn.edu [Department of Chemical & Biomolecular Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States)

    2015-10-15

    This paper presents a novel and facile method to fabricate Bi/BiOCl composites with dominant (001) facets in situ via a microwave reduction route. Different characterization techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission scanning electron microscopy (TEM), UV–vis diffuse reflectance spectrometry (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance spectroscopy (ESR), cathodoluminescence spectrum (CL), and lifetime, have been employed to investigate the structure, optical and electrical properties of the Bi/BiOCl composites. The experimental results show that the introduction of Bi particles can efficiently enhance the photocatalytic performance of BiOCl for the degradation of several dyes under ultraviolet (UV) light irradiation, especially for negative charged methyl orange (MO). Unlike the UV photocatalytic performance, such Bi/BiOCl composite shows higher degradation efficiency towards rhodamine B (RhB) than MO and methylene blue (MB) under visible light irradiation. This special photocatalytic performance can be ascribed to the synergistic effect between oxygen vacancies and Bi particles. This work provides new insights about the photodegradation mechanisms of MO, MB and RhB under UV and visible light irradiation, which would be helpful to guide the selection of an appropriate catalyst for other pollutants. - Highlights: • Bi/BiOCl composites were synthesized via a microwave reduction. • Tunable selectivity photocatalytic activity can be achieved. • Photodegradation mechanism under UV and visible light were proposed.

  13. Site controlled Red-Yellow-Green light emitting InGaN Quantum Discs on nano-tipped GaN rods

    KAUST Repository

    Conroy, Michele Ann

    2016-03-10

    We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive x-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips’ broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD’s confinement dimensions, rather than significantly increasing the In%. This article details the easily controlled method of manipulating the QDs dimensions producing high crystal quality InGaN without complicated growth conditions needed for strain relaxation and alloy compositional changes seen for bulk planar GaN templates.

  14. Direct correlation and strong reduction of native point defects and microwave dielectric loss in air-annealed (Ba,Sr)TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Z. Q. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Podpirka, A.; Kirchoefer, S. W. [Naval Research Laboratory, Washington, DC 20375 (United States); Asel, T. J. [Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States); Brillson, L. J., E-mail: brillson.1@osu.edu [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-05-04

    We report on the native defect and microwave properties of 1 μm thick Ba{sub 0.50}Sr{sub 0.50}TiO{sub 3} (BST) films grown on MgO (100) substrates by molecular beam epitaxy (MBE). Depth-resolved cathodoluminescence spectroscopy (DRCLS) showed high densities of native point defects in as-deposited BST films, causing strong subgap emission between 2.0 eV and 3.0 eV due to mixed cation V{sub C} and oxygen Vo vacancies. Post growth air anneals reduce these defects with 2.2, 2.65, and 3.0 eV V{sub O} and 2.4 eV V{sub C} intensities decreasing with increasing anneal temperature and by nearly two orders of magnitude after 950 °C annealing. These low-defect annealed BST films exhibited high quality microwave properties, including room temperature interdigitated capacitor tunability of 13% under an electric bias of 40 V and tan δ of 0.002 at 10 GHz and 40 V bias. The results provide a feasible route to grow high quality BST films by MBE through post-air annealing guided by DRCLS.

  15. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  16. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Science.gov (United States)

    Alnoor, Hatim; Chey, Chan Oeurn; Pozina, Galia; Liu, Xianjie; Khranovskyy, Volodymyr; Willander, Magnus; Nur, Omer

    2015-08-01

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  17. One-dimensional CdS nanostructures: synthesis, properties, and applications

    Science.gov (United States)

    Zhai, Tianyou; Fang, Xiaosheng; Li, Liang; Bando, Yoshio; Golberg, Dmitri

    2010-02-01

    One-dimensional (1D) semiconductor nanostructures are of prime interest due to their potential in investigating the size and dimensionality dependence of the materials' physical properties and constructing nanoscale electronic and optoelectronic devices. Cadmium sulfide (CdS) is an important semiconductor compound of the ii-vi group, and its synthesis and properties have been of growing interest owing to prominent applications in several fields. This article provides a comprehensive review of the state-of-the-art research activities that focus on the rational synthesis, novel properties and unique applications of 1D CdS nanostructures in nanotechnology. It begins with the rational design and synthesis of 1D CdS nanostructures, and then highlights a range of unique properties and applications (e.g. photoluminescence, cathodoluminescence, electrochemiluminescence, photocatalysis, lasers, waveguides, modulators, solar cells, field-effect transistors, photodetectors, field-emitters, and nanogenerators) associated with them. Finally, the review is concluded with the author outlook of the perspectives with respect to future research on 1D CdS nanostructures.

  18. Intense Red Catho- and Photoluminescence from 200 nm Thick Samarium Doped Amorphous AlN Thin Films

    Directory of Open Access Journals (Sweden)

    Ali Tariq

    2009-01-01

    Full Text Available Abstract Samarium (Sm doped aluminum nitride (AlN thin films are deposited on silicon (100 substrates at 77 K by rf magnetron sputtering method. Thick films of 200 nm are grown at 100–200 watts RF power and 5–8 m Torr nitrogen, using a metal target of Al with Sm. X-ray diffraction results show that films are amorphous. Cathodoluminescence (CL studies are performed and four peaks are observed in Sm at 564, 600, 648, and 707 nm as a result of4G5/2 → 6H5/2,4G5/2 → 6H7/2,4G5/2 → 6H9/2, and4G5/2 → 6H11/2transitions. Photoluminescence (PL provides dominant peaks at 600 and 707 nm while CL gives the intense peaks at 600 nm and 648 nm, respectively. Films are thermally activated at 1,200 K for half an hour in a nitrogen atmosphere. Thermal activation enhances the intensity of luminescence.

  19. Multi-wavelength emitting InGan/GaN quantum well grown on V-shaped gan(1101) microfacet.

    Science.gov (United States)

    Kang, Eun-Sil; Ju, Jin-Woo; Kim, Jin Soo; Ahn, Haeng-Keun; Lee, June Key; Kim, Jin Hyeok; Shin, Dong-Chan; Lee, In-Hwan

    2007-11-01

    InGaN/GaN multiple quantum wells (MQWs) were successfully grown on the inclined GaN(1101) microfacets. Conventional photolithography and subsequent growth of GaN were employed to generate the V-shaped microfacets along (1120) direction. The well-developed microfacets observed by scanning electron microscopy and the clear transmission electron microscope interfacial images indicated that the MQW was successfully grown on the GaN microfacets. Interestingly, cathodoluminescence (CL) spectra measured on the microfacets showed a continuous change in the luminescence peak positions. The CL peaks were shifted to a longer wavelength from 420 nm to 440 nm as the probing points were changed along upward direction. This could be attributed to the nonuniform distribution of the In composition and/or the wavefunction overlapping between adjacent wells. Present works thus propose a novel route to fabricate a monolithic white light emitting diode without phosphors by growing the InGaN/GaN MQWs on (1101) facet.

  20. Facet recovery and light emission from GaN/InGaN/GaN core-shell structures grown by metal organic vapour phase epitaxy on etched GaN nanorod arrays

    Science.gov (United States)

    Le Boulbar, E. D.; Gîrgel, I.; Lewins, C. J.; Edwards, P. R.; Martin, R. W.; Šatka, A.; Allsopp, D. W. E.; Shields, P. A.

    2013-09-01

    The use of etched nanorods from a planar template as a growth scaffold for a highly regular GaN/InGaN/GaN core-shell structure is demonstrated. The recovery of m-plane non-polar facets from etched high-aspect-ratio GaN nanorods is studied with and without the introduction of a hydrogen silsesquioxane passivation layer at the bottom of the etched nanorod arrays. This layer successfully prevented c-plane growth between the nanorods, resulting in vertical nanorod sidewalls (˜89.8°) and a more regular height distribution than re-growth on unpassivated nanorods. The height variation on passivated nanorods is solely determined by the uniformity of nanorod diameter, which degrades with increased growth duration. Facet-dependent indium incorporation of GaN/InGaN/GaN core-shell layers regrown onto the etched nanorods is observed by high-resolution cathodoluminescence imaging. Sharp features corresponding to diffracted wave-guide modes in angle-resolved photoluminescence measurements are evidence of the uniformity of the full core-shell structure grown on ordered etched nanorods.

  1. Effect of Eu ion incorporation on the emission behavior of Y2O3 nanophosphors: A detailed study of structural and optical properties

    Science.gov (United States)

    Kumar, Y.; Pal, Mou; Herrera, M.; Mathew, X.

    2016-10-01

    In order to investigate the effect of doping concentration on the luminescence behavior of yttrium oxide (Y2O3) europium (Eu) doped nanoparticles were prepared by co-precipitation method. Incorporation of Eu ion in Y2O3 matrix is clearly reflected in structural and optical properties of the doped Y2O3 phosphor. Cathodoluminescence (CL) spectroscopy proves the presence of strong Eu3+ emissions along with the presence of an additional weak band corresponding to electronic transitions 4f65d1 (7FJ) - 4f7 (8S7/2) of the Eu2+. The presence of Eu3+ and Eu2+ ions in Y2O3 nanoparticles have been additionally confirmed by XPS analysis. Luminescence band corresponding to Eu3+ ions appears in both CL and photoluminescence (PL) spectra, covering the orange-red emissions from 580 to 710 nm. Vibrational properties analyzed through Raman spectroscopy have revealed the evolution of different peaks associated with Eu emission in the doped Y2O3 nanocrystals.

  2. Optimization of the luminescence emission of Si nanocrystals synthesized from non-stoichiometric Si oxides using a Central Composite Design of the deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Morana, B. [Dpto. Tecnologia Electronica, E.T.S.I. de Telecomunicacion, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Sande, J.C.G. de [Dpto. Ingenieria de Circuitos y Sistemas, E.U.I.T. de Telecomunicacion, Universidad Politecnica de Madrid, 28031 Madrid (Spain); Rodriguez, A. [Dpto. Tecnologia Electronica, E.T.S.I. de Telecomunicacion, Universidad Politecnica de Madrid, 28040 Madrid (Spain)], E-mail: andres.rodriguez.dominguez@upm.es; Sangrador, J.; Rodriguez, T. [Dpto. Tecnologia Electronica, E.T.S.I. de Telecomunicacion, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Avella, M.; Jimenez, J. [Dpto. Fisica de la Materia Condensada, E.T.S.I. Industriales, Universidad de Valladolid, 47011 Valladolid (Spain)

    2008-02-15

    Si oxide films with a controlled excess of Si were deposited on Si wafers by LPCVD using Si{sub 2}H{sub 6} and O{sub 2}, thermally annealed to 1100 deg. C for 1 h to form Si nanocrystals embedded in SiO{sub 2} and subsequently annealed at 450 deg. C in forming gas. The samples were characterized by Fourier transform infrared spectroscopy, spectroscopic ellipsometry and cathodoluminescence spectroscopy. The excess of Si in the as-deposited samples, ranging from 0 to 70% in volume, was obtained from the ellipsometry data analysis. After annealing at 1100 deg. C, the samples show a luminescence band (peaking at 665 nm) at 80 K and at room temperature which is associated to the presence of Si nanocrystals. The growth rate, the excess of Si incorporated to the films and the intensity of the luminescence band were modelled using a Face-Centered Central Composite Design as a function of the main deposition variables (pressure, 185-300 mTorr; temperature, 250-400 deg. C; Si{sub 2}H{sub 6}/O{sub 2} flow ratio, 2-5) aiming to control the growth process and the incorporation of Si in excess as well as to determine the experimental conditions that yield the samples with the maximum intensity of the luminescence emission.

  3. Grassy Silica Nanoribbons and Strong Blue Luminescence

    Science.gov (United States)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-09-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

  4. Fungal Ferromanganese Mineralisation in Cretaceous Dinosaur Bones from the Gobi Desert, Mongolia.

    Directory of Open Access Journals (Sweden)

    Krzysztof Owocki

    Full Text Available Well-preserved mycelia of fungal- or saprolegnia-like biota mineralised by ferromanganese oxides were found for the first time in long bones of Late Cretaceous dinosaurs from the Gobi Desert (Nemegt Valley, Mongolia. The mycelia formed a biofilm on the wall of the bone marrow cavity and penetrated the osteon channels of the nearby bone tissue. Optical microscopy, Raman, SEM/EDS, SEM/BSE, electron microprobe and cathodoluminescence analyses revealed that the mineralisation of the mycelia proceeded in two stages. The first stage was early post-mortem mineralisation of the hyphae by Fe/Mn-oxide coatings and microconcretions. Probably this proceeded in a mildly acidic to circumneutral environment, predominantly due to heterotrophic bacteria degrading the mycelial necromass and liberating Fe and Mn sorbed by the mycelia during its lifetime. The second stage of mineralisation, which proceeded much later following the final burial of the bones in an alkaline environment, resulted from the massive precipitation of calcite and occasionally barite on the iron/manganese-oxide-coated mycelia. The mineral phases produced by fungal biofilms colonising the interiors of decaying dinosaur bones not only enhance the preservation (fossilisation of fungal remains but can also be used as indicators of the geochemistry of the dinosaur burial sites.

  5. Growth of ZnO nanostructures by femtosecond laser irradiation of polycrystalline targets

    Science.gov (United States)

    Escalante, G.; Ryu, Y. K.; de la Cruz, A. Ruíz; Puerto, D.; Solís, J.; Fernández, P.

    2015-11-01

    The formation of LIPSS upon irradiation with ultrashort laser pulses on the surface of polycrystalline ZnO samples and the potential use of irradiated areas as growth patterns for the production of highly ordered nanostructures upon redeposition have been studied. For this purpose, we have performed different sets of irradiation experiments including static irradiation experiments at low and high repetition rates, as well as scanned beam experiments at high repetition rate, this later in order to generate relatively large template regions for nanostructure growth by redeposition. In all cases, LIPSS formation has been achieved in the ZnO polycrystalline surface. Under appropriate irradiation conditions, the material is redeposited rendering a high density of nanostructures with high aspect ratios and good crystal quality. Given the special luminescent properties and applications of ZnO, particular attention has been paid to the luminescence properties after irradiation and after post-irradiation thermal treatments. The observed evolution has been correlated with evolution of point defects in the treated surfaces. Thermal treatments cause significant changes in both the topography and the cathodoluminescent emission, such as the development of laminar structures, the emergence of nucleation centers and the recovery of ultraviolet emission previously quenched as a consequence of irradiation. Interestingly, LIPSS remain after the luminescent recovery by thermal annealing, opening the possibility to control both luminescence properties and grain size while maintaining an ordered structure with a high effective surface area.

  6. SHRIMP U-Pb Dating of Zircons of a Dark Eclogite and a Garnet-bearing Gneissic Granitic Rock from Bixiling, EasternDabie Area, Anhui Province: Isotope Chronological Evidence of Neoproterozoic UHP Metamorphism

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The paper reports SHRIMP U-Pb zircon data of a dark eclogite and a post-eclogite garnet-bearing gneissic granitic rock from the Bixiling area, Yuexi County, Anhui Province, in the eastern Dabie Mountains. The eclogite, which is metamorphosed basic tuff, contains very scarce zircons in omphacite or garnet, but more zircons in quartz. They usually exhibit a double-layered texture, as shown clearly in cathodoluminescence images. Their inner main parts give a206 Pb/238U age of 757±7Ma, representing the approximate age of the high-pressure (HP)-ultrahighpressure (UHP) metamorphic event duing which the eclogite was formed. The outer peripheral parts of the zircons,which have been modified by late-stage fluids, give an age of 223±3 Ma. The granitic rock contains more zircons of anatectic origin found mostly in feldspar and quartz and usually also showing a similar composite texture. The inner main parts of the anatectic zircons with oscillatory zoning give a 206Pb/238U age of 727±15Ma for the approximate age of the emplacement of the granitic rock, and their outer parts, an age of 219±3 Ma for a similar or even the same fluid event. It is thus suggested that the HP-UHP metamorphism of the Bixiling eclogite facies rocks took place during the Neoproterozoic Jinningian,and the Indosinian age values may only represent a late event in the nature of fluid activity.

  7. Broad range tuning of structural and optical properties of Zn x Mg1-x O nanostructures grown by vapor transport method

    Science.gov (United States)

    Vanjaria, Jignesh V.; Azhar, Ebraheem Ali; Yu, Hongbin

    2016-11-01

    One-dimensional (1D) Zn x Mg1-x O nanomaterials have drawn global attention due to their remarkable chemical and physical properties, and their diverse current and future technological applications. In this work, 1D ZnMgO nanostructures with different magnesium concentrations and different morphologies were grown directly on zinc oxide-coated silicon substrates by thermal evaporation of zinc oxide, magnesium boride and graphite powders. Highly well-defined Mg-rich ZnMgO nanorods with a rock salt structure and Zn-rich ZnMgO nanostructures with a wurtzite structure have been deposited individually by careful optimization of the source mixture and process parameters. Structural and optical properties of the deposited products were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy. Cathodoluminescence measurements demonstrate strong dominant peaks at 3.3 eV in Mg poor ZnMgO nanostructures and 4.8 eV in Mg rich nanostructures implying that the ZnMgO nanostructures can be used for the fabrication of deep UV optoelectronic devices. A mechanism for the formation and achieved diverse morphology of the ZnMgO nanostructures was proposed based on the characterization results.

  8. Modification of optical and electrical properties of zinc oxide-coated porous silicon nanostructures induced by swift heavy ion.

    Science.gov (United States)

    Kumar, Yogesh; Herrera-Zaldivar, Manuel; Olive-Méndez, Sion Federico; Singh, Fouran; Mathew, Xavier; Agarwal, Vivechana

    2012-07-02

    Morphological and optical characteristics of radio frequency-sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130 MeV of nickel ions at different fluences varying from 1 × 1012 to 3 × 1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence spectroscopy. Current-voltage characteristics of ZnO-PS heterojunctions were also measured. As compared to the granular crystallites of zinc oxide layer, Al-doped zinc oxide (ZnO) layer showed a flaky structure. The PL spectrum of the pristine composite structure consists of the emission from the ZnO layer as well as the near-infrared emission from the PS substrate. Due to an increase in the number of deep-level defects, possibly oxygen vacancies after swift ion irradiation, PS-Al-doped ZnO nanocomposites formed with high-porosity PS are shown to demonstrate a broadening in the PL emission band, leading to the white light emission. The broadening effect is found to increase with an increase in the ion fluence and porosity. XRD study revealed the relative resistance of the film against the irradiation, i.e., the irradiation of the structure failed to completely amorphize the structure, suggesting its possible application in optoelectronics and sensing applications under harsh radiation conditions.

  9. Growth of AlGaN stripes with semipolar side facets as waveguide claddings for semipolar laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Leute, Robert Anton Richard; Forghani, Kamran; Lipski, Frank; Scholz, Ferdinand [Institut fuer Optoelektronik, Universitaet Ulm (Germany); Tischer, Ingo; Neuschl, Benjamin; Thonke, Klaus [Institut fuer Quantenmaterie, Gruppe Halbleiterphysik, Universitaet Ulm (Germany)

    2011-07-01

    Selective area growth of group III nitrides allows the epitaxy of semipolar facets with reduced piezoelectric field on 2-inch sapphire substrates. Additionally, the 3D growth of stripes, pyramids or the like enables us to manipulate the extraction and propagation of light by changing the surface topology. LEDs grown on GaN stripes with {l_brace}11 anti 22{r_brace} facets and GaN stripes with {l_brace}10 anti 11{r_brace} facets have been published. The fabrication of laser structures with resonators along the stripes depends critically on the controlled growth of a waveguide cladding for optical confinement, typically realized by AlGaN layers. However, the growth parameters of AlGaN are challenging for selective epitaxy. The high growth temperature promotes lateral growth, leading to the emergence of an undesirable c-plane facet, whereas the reduced selectivity of the mask material for Al atoms leads to polycrystalline growth on masked areas. We investigate the selective growth of AlGaN with Al contents up to 10% with structured SiO{sub 2} and SiN{sub x} masks. The influence of mask geometries (stripes parallel m and perpendicular to m, variable opening sizes and periods) on topology, material quality and Al incorporation is examined. Therefore, we present SEM investigations, spatially resolved cathodoluminescence as well as low temperature photoluminescence.

  10. Wafer-scale crack-free AlGaN on GaN through two-step selective-area growth for optically pumped stimulated emission

    Science.gov (United States)

    Ko, Young-Ho; Bae, Sung-Bum; Kim, Sung-Bock; Kim, Dong Churl; Leem, Young Ahn; Cho, Yong-Hoon; Nam, Eun-Soo

    2016-07-01

    Crack-free AlGaN template has been successfully grown over entire 2-in. wafer by using 2-step selective-area growth (SAG). The GaN truncated structure was obtained by vertical growth mode with low growth temperature. AlGaN of second step was grown under lateral growth mode. Low pressure enhanced the relative ratio of lateral to vertical growth rate as well as absolute overall growth rate. High V/III ratio was favorable for lateral growth mode. Crack-free planar AlGaN was obtained under low pressure of 30 Torr and high V/III ratio of 4400. The AlGaN was crack-free over entire 2-in. wafer and had quite uniform Al-mole fraction. The dislocation density of the AlGaN with 20% Al-composition was as low as ~7.6×108 /cm2, measured by cathodoluminescence. GaN/AlGaN multi-quantum well (MQW) with cladding and waveguide layers were grown on the crack-free AlGaN template with low dislocation density. It was confirmed that the MQW on the AlGaN template emitted the stimulated emission at 355.5 nm through optical pumping experiment. The AlGaN obtained by 2-step SAG would provide high crystal quality for highly-efficient optoelectronic devices as well as the ultraviolet laser diode.

  11. Versatile properties of CaGd₂ZnO₅:Eu³⁺ nanophosphor: its compatibility for lighting and optical display applications.

    Science.gov (United States)

    Raju, G Seeta Rama; Pavitra, E; Nagaraju, Goli; Yu, Jae Su

    2015-01-28

    Red color-emitting CaGd2ZnO5:Eu(3+) (CGZO:Eu(3+)) nanophosphors were synthesized by a facile sol-gel process. The structural and luminescent properties of these phosphors were investigated as a function of annealing temperature and Eu(3+) ion concentration. The orthorhombic phase was confirmed at different annealing temperatures, showing an irregular morphology within the nanoscale range. Photoluminescence (PL) excitation spectra of CGZO:Eu(3+) showed host absorption band (HAB), charge transfer band (CTB), and intense f-f transitions of Eu(3+) in the violet and blue wavelength regions. The CTB intensity increased and the HAB intensity decreased with increasing annealing temperature or Eu(3+) ion concentration. The CGZO:Eu(3+) exhibited a strong absorption in the blue region as compared to the CTB and had a superior property compared to available commercial phosphors. This feature facilitates the fabrication of high color rendering index white light-emitting diodes for display systems. In PL spectra, an intense red emission was observed due to the hypersensitive (5)D0→(7)F2 transition with good asymmetry ratio and chromaticity coordinates. Optimized annealing temperature and concentration of Eu(3+) ions were observed for CGZO host lattice based on the 466 nm excitation wavelength. The cathodoluminescent properties were also similar to the PL results.

  12. Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration.

    Science.gov (United States)

    Yuan, Haifeng; Debroye, Elke; Janssen, Kris; Naiki, Hiroyuki; Steuwe, Christian; Lu, Gang; Moris, Michèle; Orgiu, Emanuele; Uji-I, Hiroshi; De Schryver, Frans; Samorì, Paolo; Hofkens, Johan; Roeffaers, Maarten

    2016-02-04

    Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques.

  13. Luminescence and Structure of ZnO Grown by Physical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    R. García-Gutiérrez

    2012-01-01

    Full Text Available Nanostructured ZnO was deposited on different substrates (Si, SiO2, and Au/SiO2 by an enhanced physical vapor deposition technique that presents excellent luminescent properties. This technique consists in a horizontal quartz tube reactor that uses ultra-high purity Zn and UHP oxygen as precursors. The morphology and structure of ZnO grown in this work were studied by electron microscopy and X-ray diffraction. The XRD patterns revealed the highly crystalline phase of wurtzite polycrystalline structure, with a preferred (1011 growth direction. Room temperature cathodoluminescence studies revealed two features in the luminescence properties of the ZnO obtained by this technique, first a high-intensity narrow peak centered at 390 nm (~3.2 eV corresponding to a near band-to-band emission, and secondly, a broad peak centered around 517 nm (2.4 eV, the typical green-yellow luminescence, related to an unintentionally doped ZnO.

  14. Structure and optoelectronic properties of single crystal epitaxial Cu(In{sub 1{minus}x}Ga{sub x})Se{sub 2} and ordered defect compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rockett, A.; Berry, G.; Schroeder, D.; Xiao, H.Z.; Yang, L.C. [Univ. of Illinois, Urbana, IL (United States)

    1994-12-31

    Epitaxial CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} was grown on As-terminated (111) GaAs between 550 to 735 C with 0 {le} x {le} 1. The Cu/[In+Ga] ratio, y, ranged from y = 0.3 to 1.3. Analysis of the deposited films showed an ordered defect structure that was homogeneous throughout the epitaxial layers when rich in group III for all Ga contents examined. Films grown with y = 0.3 had energy gaps of {approximately}1.2 eV and showed evidence by both cathodoluminescence and optical absorption of band tails. Stacking faults affect both the growth rate and the luminescence but can be converted to dislocations by rapid thermal annealing. The highest hole mobilities to date, > 1,500 cm{sup 2}/V-sec, were measured at 50--75K by Hall-effect in near-stoichiometry samples. Room temperature hole mobilities were > 200 cm{sup 2}/V-sec and increased at low temperatures. Hole concentrations showed evidence of a level 80 meV above the valence band edge at a concentration in excess of 10{sup 17} cm{sup {minus}3} in all p-type samples. A composition-dependent level at {approximately}40 meV and type conversion at {approximately}100 K was also observed.

  15. Monazite geochronology, magmatism, and extensional dynamics within the Menderes Massif, western Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Catlos, E J [University of Texas at Austin, Jackson School of Geosciences, Geological Science Department, 1 University Station C1100, Austin, TX 78712-0254 (United States); Baker, C B; Cemen, I [Oklahoma State University, School of Geology, 105 Noble Research Center, Stillwater, OK 74078 (United States); Sorensen, S S [Smithsonian Institution Museum of Natural History, PO Box 37012, MRC 119, Washington, DC, 20013-7012 (United States); Hancer, M [Pamukkale Universitesi, Muhendislik Fakultesi, Jeoloji Muh. Bolmu, Denizli, 20070 Turkey (Turkey)], E-mail: ejcatlos@gmail.com

    2008-07-01

    Geochemical and geochronological data were collected from S-type, peraluminous granites (Salihli and Turgutlu) that intrude a detachment that bounds the northern edge of the central Menderes Massif core complex (Aegean region, western Turkey). The granites may have been generated due to subduction of the Eastern Mediterranean floor along the Hellenic trench. In situ Th-Pb ion microprobe monazite ages from the rocks range from 21.7{+-}4.5 Ma to 9.6{+-}1.6 Ma ({+-}1{sigma}), which could record their exhumation history. Higher uncertainty in the ages is attributed to monazite common Pb, but the range is consistent with cathodoluminescence (CL) images that document complex textures within the granites. Salihli and Turgutlu granites share many similar characteristics, including multiple generations of plagioclase, plagioclase replacing K-feldspar and the development of myrmekite, evidence for fluid interaction, and multiple generations of microcracks. Ages reported here are similar to dates constraining extension reported elsewhere in the Aegean, but indicate additional complexities when linking movement within the Menderes Massif to large-scale geodynamic processes that created other metamorphic core complexes in the region. Difficulties exist in linking the ages obtained from the granites to specific tectonic events due to the presence of secondary alteration textures, generations of mineral growth and multiple episodes of deformation.

  16. Electron-beam irradiation effects on luminescence properties in subsurface regions of single-crystalline sapphires treated with and without hydrogen plasma exposures

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Bo-Hyun [Department of Electrical Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)]. E-mail: bhlee@daiyan.eei.eng.osaka-u.ac.jp; Ito, Toshimichi [Department of Electrical Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2007-10-15

    Electron irradiation effects on various insulating sapphires treated with and without hydrogen plasma have been investigated mainly by means of cathodoluminescence (CL) measurements. The samples examined included Be-diffusion-treated natural sapphire (BNS) and two types of synthetic sapphires grown by Verneuil and Czochralski methods. For all the samples examined, on one hand, their CL intensities of the F{sup +}-center-related emission peaked at {approx}3.8 eV rapidly increased with increasing the fluences of keV electrons, and were represented roughly by exponentially saturating curves. There occurred slight blue-shifts of the F{sup +}-center luminescence other than the intensity increases for some of the electron-irradiated specimens, suggesting possible presence of two components for the F{sup +}-center luminescence. On the other hand, a hydrogen plasma exposure to these sapphires resulted in sample-dependent changes in the optical property and in the beam-irradiation effect on the F{sup +}-center CL emission. Such variations were induced most strongly in the BNS sample, whose color changed from orange to pink due to substantial decreases in the absorbance after the hydrogen plasma treatment. Furthermore, the energy positions of both the Cr{sup 3+}-center luminescence peaked at {approx}1.8 eV and its satellite peaks were found to slightly shift for the untreated and H-plasma-treated BNS samples after the electron beam irradiations. Possible origins of these observations are discussed.

  17. Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain).

    Science.gov (United States)

    Gomez-Gonzalez, M A; Garcia-Guinea, J; Laborda, F; Garrido, F

    2015-12-01

    Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system.

  18. Nanoscale conductive pattern of the homoepitaxial AlGaN/GaN transistor.

    Science.gov (United States)

    Pérez-Tomás, A; Catalàn, G; Fontserè, A; Iglesias, V; Chen, H; Gammon, P M; Jennings, M R; Thomas, M; Fisher, C A; Sharma, Y K; Placidi, M; Chmielowska, M; Chenot, S; Porti, M; Nafría, M; Cordier, Y

    2015-03-20

    The gallium nitride (GaN)-based buffer/barrier mode of growth and morphology, the transistor electrical response (25-310 °C) and the nanoscale pattern of a homoepitaxial AlGaN/GaN high electron mobility transistor (HEMT) have been investigated at the micro and nanoscale. The low channel sheet resistance and the enhanced heat dissipation allow a highly conductive HEMT transistor (Ids > 1 A mm(-1)) to be defined (0.5 A mm(-1) at 300 °C). The vertical breakdown voltage has been determined to be ∼850 V with the vertical drain-bulk (or gate-bulk) current following the hopping mechanism, with an activation energy of 350 meV. The conductive atomic force microscopy nanoscale current pattern does not unequivocally follow the molecular beam epitaxy AlGaN/GaN morphology but it suggests that the FS-GaN substrate presents a series of preferential conductive spots (conductive patches). Both the estimated patches density and the apparent random distribution appear to correlate with the edge-pit dislocations observed via cathodoluminescence. The sub-surface edge-pit dislocations originating in the FS-GaN substrate result in barrier height inhomogeneity within the HEMT Schottky gate producing a subthreshold current.

  19. XPS analysis and luminescence properties of thin films deposited by the pulsed laser deposition technique

    Science.gov (United States)

    Dolo, J. J.; Swart, H. C.; Coetsee, E.; Terblans, J. J.; Ntwaeaborwa, O. M.; Dejene, B. F.

    2010-04-01

    This paper presents the effect of substrate temperature and oxygen partial pressure on the photoluminescence (PL) intensity of the Gd2O2S:Tb3 + thin films that were grown by using pulsed laser deposition (PLD). The PL intensity increased with an increase in the oxygen partial pressure and substrate temperature. The thin film deposited at an oxygen pressure of 900 mTorr and substrate temperature of 900°C was found to be the best in terms of the PL intensity of the Gd2O2S:Tb3 + emission. The main emission peak due to the 5D4-7F5 transition of Tb was measured at a wavelength of 545 nm. The stability of these thin films under prolonged electron bombardment was tested with a combination of techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Cathodoluminescence (CL) spectroscopy. It was shown that the main reason for the degradation in luminescence intensity under electron bombardment is the formation of a non-luminescent Gd2O3 layer, with small amounts of Gd2S3, on the surface.

  20. Nondestructive mapping of chemical composition and structural qualities of group III-nitride nanowires using submicron beam synchrotron-based X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Bonanno, P.L., E-mail: plb2@njit.edu [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gautier, S. [LMOPS + UMI: Laboratoire Matériaux Optiques, Photonique et micro-nano Systèmes, UMR CNRS 7132, Université de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz, France, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gmili, Y.El.; Moudakir, T. [UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Sirenko, A.A. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Kazimirov, A. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Cai, Z.-H. [Advanced Photon Source, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Martin, J. [LMOPS + UMI: Laboratoire Matériaux Optiques, Photonique et micro-nano Systèmes, UMR CNRS 7132, Université de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz, France, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Goh, W.H. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Martinez, A.; Ramdane, A.; Le Gratiet, L. [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Maloufi, N. [Laboratoire d' Etude des Textures et Application aux Matériaux UMR CNRS 7078 Ile du Saulcy 57045 METZ cedex 1 (France); Assouar, M.B. [Laboratoire de Physique des Milieux Ionisés et Applications, Nancy University, CNRS, BP 239, F-54506 Vandoeuvre-lès-Nancy Cédex (France); Ougazzaden, A. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France)

    2013-08-31

    Submicron beam synchrotron-based X-ray diffraction (XRD) techniques have been developed and used to accurately and nondestructively map chemical composition and material quality of selectively grown group III-nitride nanowires. GaN, AlGaN, and InGaN multi-quantum-well nanowires have been selectively grown on lattice matched and mismatched substrates, and the challenges associated with obtaining and interpreting submicron beam XRD results are addressed and solved. Nanoscale cathodoluminescence is used to examine exciton behavior, and energy-dispersive X-ray spectroscopy is used to verify chemical composition. Scanning transmission electron microscopy is later used to paint a more complete picture. The advantages of submicron beam XRD over other techniques are discussed in the context of this challenging material system. - Highlights: ► We used nano selective area growth to create nanowires of GaN, AlGaN and InGaN/GaN. ► We characterized them by synchrotron-based submicron beam X-ray diffraction (XRD). ► This technique accurately determined chemical and crystallographic properties. ► Challenges of XRD are addressed in the context of this challenging material system. ► Advantages of XRD over other characterization methods are discussed.

  1. Influence of Rare Earth Elements on Luminescent Properties of Y2SiO5:Tb

    Institute of Scientific and Technical Information of China (English)

    Jiao Huan; Liao Fuhui; Zhou Jingjing; Jing Xiping

    2005-01-01

    Photoluminescent(PL) and cathodoluminescent(CL) properties of rare earths (Sc3+, La3+, Gd3+ and Lu3+) doped (Y0.97Tb0.03)2SiO5 were studied. Rare earth doping clearly influences PL and CL properties of Y2SiO5:Tb. For La3+ doped system, PL intensity increases nearly 10% at x=0.05 whereas for Lu3+ doped system, the intensity increases about 20% at x=0.20. Gd3+ doping and Sc3+ doping reduce the intensity; at x=0.3, it is reduced about 30% for Gd3+ doped system and about 15% for Sc3+ doped system, respectively. Quenching concentration of activator became higher in rare earth doped samples, which may be understood by that the rare earth dopants might dilute the concentration of the activator. Additionally, doping also influences the color saturation of Y2SiO5:Tb. Sc3+, La3+, and Gd3+ doping improve the color saturation, whereas Lu3+ doping decreases the color saturation. CL measurements show that CL intensity increases for all rare earths doped systems. The energy transfer from Gd3+ to Tb3+ was discussed.

  2. United Arab Emirates limestones: impact of petrography on thermal behavior

    Science.gov (United States)

    Alaabed, Sulaiman; Soltan, Abdel Monem; Abdelghany, Osman; Amin, Bahaa Eldin Mahmoud; El Tokhi, Mohamed; Khaleel, Abbas; Musalim, Abdullah

    2014-12-01

    The thermal behavior of selected limestones from representative localities of the United Arab Emirates is investigated for their suitability for soft-burnt lime production. The limestone samples were collected from the Ghalilah, Musandam, Shauiba, Muthaymimah, Dammam and Asmari formations. The samples were characterized for petrography, mineral and chemical composition, together with physico-mechanical characteristics. Investigative methods included transmitted light microscopy (TLM), cathodoluminescence (CLM) and scanning electron microscopy (SEM), as well as X-ray micro-tomography (μ-CT), XRD, XRF and Archimedes method. The limestone samples were fired in an electrical muffle furnace for 0.25, 0.5, 1 and 2 hours at 800, 900, 1,000 and 1,100 °C. After firing the lime grains were tested to determine their hydration rate and microfabric. The Ghalilah and Musandam limes show the lowest and highest maximum hydration rates, respectively, due mainly to the impure nature of the former, and the smaller lime crystallites and dominance of post-calcination micro-cracks of the latter. The Dammam and Asmari limes preserve a "ghost" microfabric of the original limestone. Higher allochem contents impose lower activation energy requirements for calcination, which implies earlier calcination of the allochems. The Musandam, Shauiba and Muthaymimah limestones may be useful for the production of reactive soft-burnt lime under the applied firing conditions, however, the Dammam and Asmari limestones need more advanced calcination conditions than the applied ones. The Ghalilah limestone was found to be unsuitable for the production of lime.

  3. Carbon- and Sulfur-bearing Minerals in the Martian Meteorite ALH 84001

    Science.gov (United States)

    Romanek, C. S.; Thomas, K. L.; Gibson, E. K., Jr.; McKay, D. S.; Socki, R. A.

    1995-09-01

    Unusual carbonate minerals in ALH 84001 [1] provide insights into surficial processes that may have occurred on Mars, but despite detailed geochemical studies [2-4] carbonate petrogenesis has yet to be fully-characterized. High-resolution TEM and SEM analyses were performed on C- and S-bearing mineral grains to better constrain the nature and timing of carbonate mineralization events. Morphological elements: C- and S-bearing minerals in ALH 84001 commonly occur as spheroidal aggregates or fine-grained vug-filling structures. Spheroids are either orange or black, ~150 micrometers (+/- 50 micrometers) in diameter and highly-flattened (10-30 micrometers thick). Orange spheroids have limpid amber-colored cores and white to translucent mantles which are sometimes bound by thin black rims (White mantles of the orange spheroids are composed of nearly pure MgCO3 (Harvey and McSween (1995) LPS XXVI, 555. [5] Marshall D. J. (1988) Cathodoluminescence of Geologic Materials, Unwin Hyman. [6] Mucci A. and Morse J. W. (1990) Aquatic Sci., 3, 217. [7] Mozley P. S. and Carothers W. W. (1992) J. Sed. Petrol., 62, 681.

  4. Luminescence of yttrium niobium-tantalate doubly activated by europium and/or terbium under X-ray and electron beam excitation

    Energy Technology Data Exchange (ETDEWEB)

    Arellano, I.D., E-mail: arellano@utp.edu.co [Department of Physics, Technological University of Pereira, Vereda La Julita, Pereira (Colombia); Nazarov, M.V. [Institute of Applied Physics, Academy of Sciences of Moldova, Republic of Moldova (Moldova, Republic of); School of Materials and Mineral Resources Engineering Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Cortes, J.A. [Department of Physics, Technological University of Pereira, Vereda La Julita, Pereira (Colombia); Ahmad Fauzi, M.N [School of Materials and Mineral Resources Engineering Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2012-09-15

    This paper reports the luminescence emission spectra of Y(Ta,Nb)O{sub 4} activated by rare earth ions such as Eu{sup 3+} and Tb{sup 3+}. The influence of these rare earth ions on the luminescence of yttrium niobium-tantalate phosphors was investigated. The luminescent properties were studied under X-ray and electron beam excitations. Under these excitations, the emission centers of the rare earth activators (Eu{sup 3+},Tb{sup 3+}) were found to contribute efficiently to the overall luminescence. Changing the mol concentration of the incorporated activators resulted in a broad variation of visible photoluminescence. Color cathodoluminescence images showed clearly the dependence of chromaticity on the different activators. With their various luminescence chromaticities, these rare earth activated phosphors are promising materials for solid-state lighting applications as well as for X-ray intensifying screens in medical diagnosis, providing a broad variation of visible photoluminescence from blue to red. - Highlights: Black-Right-Pointing-Pointer The Y(Ta,Nb)O{sub 4} phosphors were activated by rare earth ions such as Eu{sup 3+} and Tb{sup 3+}. Black-Right-Pointing-Pointer The phosphors were studied under X-ray and electron beam excitations. Black-Right-Pointing-Pointer The emission centers contribute efficiently to the overall luminescence. Black-Right-Pointing-Pointer Changing the concentration of the activators resulted in a broad luminescence.

  5. Luminescence behaviour of beryl (aquamarine variety) from Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Kat Latin-Small-Letter-Dotless-I , M.I.; Tueremis, M.; Keskin, I.C.; Tastekin, B.; Kibar, R.; Cetin, A. [Celal Bayar University, Faculty of Arts and Sciences, Physics Department, 45140 Manisa (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Physics Department, 45140 Manisa (Turkey)

    2012-10-15

    Natural blue-green beryl from Turkey has been investigated using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and Cathodoluminescence (CL). Beryl has the chemical formula Be{sub 3}Al{sub 2}Si{sub 6}O{sub 18} and is hexagonal with space group P6/mcc. Chemical analyses of the beryl sample utilised inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for major oxides and trace elements. It shows that the beryl sample is rich in Cs (531 ppm) and contains low concentrations of transition-metal ions, in total 2.29 wt.% Fe, 269 ppm Mn, V<5 ppm and Cr 20 ppm. Ideas on the origin of the green colour of this mineral are presented. The CL spectrum of the bulk sample display intense broad band emission from {approx}360 to {approx}800 nm. - Highlights: Black-Right-Pointing-Pointer Natural blue-green beryl from Turkey were investigated by SEM-EDS, XRD, CL. Black-Right-Pointing-Pointer Luminescence behaviour of Natural blue-green beryl. Black-Right-Pointing-Pointer The samples exhibit an intense broad band emission from {approx}360 to {approx}800 nm.

  6. Pressure–Temperature–Fluid Constraints for the Poona Emerald Deposits, Western Australia: Fluid Inclusion and Stable Isotope Studies

    Directory of Open Access Journals (Sweden)

    Dan Marshall

    2016-12-01

    Full Text Available Emerald from the deposits at Poona shows micrometre-scale chemical, optical, and cathodoluminescence zonation. This zonation, combined with fluid inclusion and isotope studies, indicates early emerald precipitation from a single-phase saline fluid of approximately 12 weight percent NaCl equivalent, over the temperature range of 335–525 °C and pressures ranging from 70 to 400 MPa. The large range in pressure and temperature likely reflects some post entrapment changes and re-equilibration of oxygen isotopes. Secondary emerald-hosted fluid inclusions indicate subsequent emerald precipitation from higher salinity fluids. Likewise, the δ18O-δD of channel fluids extracted from Poona emerald is consistent with multiple origins yielding both igneous and metamorphic signatures. The combined multiple generations of emerald precipitation, different fluid compositions, and the presence of both metamorphic and igneous fluids trapped in emerald, likely indicate a protracted history of emerald precipitation at Poona conforming to both an igneous and a metamorphic origin at various times during regional lower amphibolite to greenschist facies metamorphism over the period ~2710–2660 Ma.

  7. Multi-Stage Silicification of Pliocene Wood: Re-Examination of an 1895 Discovery from Idaho, USA

    Directory of Open Access Journals (Sweden)

    Mike Viney

    2016-04-01

    Full Text Available The 1895 discovery of a petrified tree near Clover Creek in south-central Idaho, USA, attracted worldwide attention and resulted in the naming of a new species of ancient oak, Quercinium pliocaenicum Schuster. For more than a century, the discovery has largely been forgotten, even though specimens reside in reputable museums. Reinvestigation of the locality in 2014/2015 resulted in newly-collected specimens and a wealth of new data. Optical microscopy confirms the cellular anatomy used for the original taxonomic study. X-ray diffraction, scanning electron microscopy, energy-dispersive electron spectroscopy, Raman spectroscopy and cathodoluminescence microscopy reveal details of the mineralization, showing the presence of opal-CT as the primary component, with chalcedony as a lesser constituent. This mineralogy suggests petrifaction occurred in at least two stages, beginning with opalization of cellular tissue, leaving open vessels that became filled with chalcedony during a later mineralization episode. Clover Creek oak represents relict flora growing in a wetter climate before the uplift of the Cascade Range created a rain shadow that caused profound desertification of the inland Pacific Northwest.

  8. Hybrid plasmonic-photonic resonators (Conference Presentation)

    Science.gov (United States)

    Koenderink, A. Femius; Doeleman, Hugo M.; Ruesink, Freek; Verhagen, Ewold; Osorio, Clara I.

    2016-09-01

    Hybrid nanophotonic structures are structures that integrate different nanoscale platforms to harness light-matter interaction. We propose that combinations of plasmonic antennas inside modest-Q dielectric cavities can lead to very high Purcell factors, yielding plasmonic mode volumes at essentially cavity quality factors. The underlying physics is subtle: for instance, how plasmon antennas with large cross sections spoil or improve cavities and vice versa, contains physics beyond perturbation theory, depending on interplays of back-action, and interferences. This is evident from the fact that the local density of states of hybrid systems shows the rich physics of Fano interferences. I will discuss recent scattering experiments performed on toroidal microcavities coupled to plasmon particle arrays that probe both cavity resonance shifts and particle polarizability changes illustrating these insights. Furthermore I will present our efforts to probe single plasmon antennas coupled to emitters and complex environments using scatterometry. An integral part of this approach is the recently developed measurement method of `k-space polarimetry', a microscopy technique to completely classify the intensity and polarization state of light radiated by a single nano-object into any emission direction that is based on back focal plane imaging and Stokes polarimetry. I show benchmarks of this technique for the cases of scattering, fluorescence, and cathodoluminescence applied to directional surface plasmon polariton antennas.

  9. A carbon fiber-ZnS nanocomposite for dual application as an efficient cold cathode as well as a luminescent anode for display technology.

    Science.gov (United States)

    Jha, Arunava; Sarkar, Sudipta Kumar; Sen, Dipayan; Chattopadhyay, K K

    2015-02-14

    In the current work we present a simple technique to develop a carbon nanofiber (CNF)/zinc sulfide (ZnS) composite material for excellent FED application. CNFs and ZnS microspheres were synthesized by following a simple thermal chemical vapor deposition and hydrothermal procedure, respectively. A rigorous chemical mixture of CNF and ZnS was prepared to produce the CNF-ZnS composite material. The cathodo-luminescence intensity of the composite improved immensely compared to pure ZnS, also the composite material showed better field emission than pure CNFs. For pure CNF the turn-on field was found to be 2.1 V μm(-1) whereas for the CNF-ZnS composite it reduced to a value of 1.72 V μm(-1). Altogether the composite happened to be an ideal element for both the anode and cathode of a FED system. Furthermore, simulation of our CNF-ZnS composite system using the finite element modeling method also ensured the betterment of field emission from CNF after surface attachment of ZnS nanoclusters.

  10. Hybridization between nanocavities for a polarimetric color sorter at the sub-micron scale.

    Science.gov (United States)

    Segal, Elad; Weissman, Adam; Gachet, David; Salomon, Adi

    2016-08-18

    Metallic hole arrays have been recently used for color generation and filtering due to their reliability and color tunability. However, color generation is still limited to several microns. Understanding the interaction between the individual elements of the whole nanostructure may push the resolution to the sub-micron level. Herein, we study the hybridization between silver nanocavities in order to obtain active color generation at the micron scale. To do so, we use five identical triangular cavities which are separated by hundreds of nanometers from each other. By tuning either the distance between the cavities or the optical polarization state of the incoming field, the transmitted light through the cavities is actively enhanced at specific frequencies. Consequently, a rainbow of colors is observed from a sub-micron scale unit. The reason for this is that the metallic surface plays a vital role in the hybridization between the cavities and contributes to higher frequency modes. Cathodoluminescence measurements have confirmed this assumption and have revealed that these five triangular cavities act as a unified entity surrounded by the propagated surface plasmons. In such plasmonic structures, multi-color tuning can be accomplished and may open the possibility to improve color generation and high-quality pixel fabrication.

  11. Optical properties of InN studied by spectroscopic ellipsometry

    Science.gov (United States)

    Chunya, Ye; Wei, Lin; Jin, Zhou; Shuping, Li; Li, Chen; Heng, Li; Xiaoxuan, Wu; Songqing, Liu; Junyong, Kang

    2016-10-01

    With recently developed InN epitaxy via a controlling In bilayer, spectroscopic ellipsometry (SE) measurements had been carried out on the grown InN and the measured ellipsometric spectra were fitted with the Delta Psi2 software by using a suitable model and the dispersion rule. The thickness was measured by a scanning electron microscope (SEM). Insight into the film quality of InN and the lattice constant were gained by X-ray diffraction (XRD). By fitting the SE, the thickness of the InN film is consistent with that obtained by SEM cross-sectional thickness measurement. The optical bandgap of InN was put forward to be 1.05 eV, which conforms to the experimental results measured by the absorption spectrum and cathodoluminescence (CL). The refractive index and the extinction coefficient of interest were represented for InN, which is useful to design optoelectronic devices. Project supported by the State Key Development Program for Basic Research of China (No. 2012CB619301), the National High Technology Research and Development Program of China (No. 2014AA032608), the National Natural Science Foundation of China (Nos. 11204254, 11404271), and the Fundamental Research Funds for the Central Universities (Nos. 2012121014, 20720150027).

  12. Characters of fluid inclusions in quartz veins in pyroclastic rock of Budate Group, Hailar Basin

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-tao; LIU Li; GAO Yu-qiao; SHAO Hong-mei; SHEN Guang-zheng

    2004-01-01

    It was adopted that the fluorescence microscope, Gas-Flow Heating/Freezing System, Laser-Raman Spectroscopy, etc. are the multimedia techniques for analysing fluid inclusions of quartz veins in Budate Group, Hailar Basin.The results show that fluid inclusions in quartz veins are small (1 ~5 μm) monophase, two-phase (liquid+vapour)aqueous inclusions; the two-phase aqueous inclusions homogeniese to the liquid phase between 120 ~ 180℃, two Laser-Raman Spectroscopy show that both gas phase are enriched in CH4 (94.50% ~99.25% ) and C6H6 (0.75% ~2.70%), under these conditions, inclusions may have come from juvenile fliud followingly the quartz veins formation.While the quartz veins exhibiting different striking luminescence has been proved by cathodoluminescence, it would be belong to secondary hydrocarbon inclusions. The oil inclusions of this stage represent mainly the large scale of oil accumulation, located within the quartz microfracture.

  13. Exposure vs toxicity levels of airborne quartz, metal and carbon particles in cast iron foundries.

    Science.gov (United States)

    Moroni, Beatrice; Viti, Cecilia; Cappelletti, David

    2014-01-01

    Aerosol dust samples and quartz raw materials from different working stations in foundry plants were characterized in order to assess the health risk in this working environment. Samples were analysed by scanning and transmission electron microscopy coupled with image analysis and microanalysis, and by cathodoluminescence spectroscopy. In addition, the concentration and the solubility degree of Fe and other metals of potential health effect (Mn, Zn and Pb) in the bulk samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Overall, the results indicate substantial changes in quartz crystal structure and texture when passing from the raw material to the airborne dust, which include lattice defects, non-bridging oxygen hole centres and contamination of quartz grains by metal and/or graphite particles. All these aspects point towards the relevance of surface properties on reactivity. Exposure doses have been estimated based on surface area, and compared with threshold levels resulting from toxicology. The possible synergistic effects of concomitant exposure to inhalable magnetite, quartz and/or graphite particles in the same working environment have been properly remarked.

  14. Disentangling the effects of nanoscale structural variations on the light emission wavelength of single nano-emitters: InGaN/GaN multiquantum well nano-LEDs for a case study.

    Science.gov (United States)

    Sarau, George; Heilmann, Martin; Latzel, Michael; Christiansen, Silke

    2014-10-21

    The scattering in the light emission wavelength of semiconductor nano-emitters assigned to nanoscale variations in strain, thickness, and composition is critical in current and novel nanotechnologies from highly efficient light sources to photovoltaics. Here, we present a correlated experimental and theoretical study of single nanorod light emitting diodes (nano-LEDs) based on InGaN/GaN multiquantum wells to separate the contributions of these intrinsic fluctuations. Cathodoluminescence measurements show that nano-LEDs with identical strain states probed by non-resonant micro-Raman spectroscopy can radiate light at different wavelengths. The deviations in the measured optical transitions agree very well with band profile calculations for quantum well thicknesses of 2.07-2.72 nm and In fractions of 17.5-19.5% tightly enclosing the growth values. The nanorod surface roughness controls the appearance of surface optical phonon modes with direct implications on the design of phonon assisted nano-LED devices. This work establishes a new, simple, and powerful methodology for fundamental understanding as well as quantitative analysis of the strain - light emission relationship and surface-related phenomena in the emerging field of nano-emitters.

  15. Fluid inclusion and isotopic evidence on dolomitization, Devonian of Western Canada

    Energy Technology Data Exchange (ETDEWEB)

    Aulstead, K.L.; Spencer, R.J.; Krouse, H.R. (Univ. of Calgary, Alberta (Canada))

    1988-05-01

    The Presqu'ile and Manetoe Facies are diagenetic features developed in Lower and Middle Devonian Formations of the Elk Point Basin (Presqu'ile) and the Mackenzie Shelf (Manetoe). Both facies contain coarsely crystalline dolomite and white sparry dolomite cement. Less extensive diagenetic phases, in order of paragenesis, include fluorite, anhydrite, barite, calcite, quartz, sphalerite and galena. Conditions of dolomitization are outlined from core and outcrop examination, thin section and cathodoluminescent petrography, fluid inclusion analyses, and C and O isotopic data. Fluid inclusion and stable isotope analyses from dolomite are combined to determine the isotopic composition of the dolomitizing fluids. Chemical analyses of fluid inclusion waters are compared with formation water analyses to derive a proposed origin for the diagenetic fluids. Dolomite formed from hot, high salinity fluids early in the diagenetic history of the basin. Limestone was dolomitized as a result of the same process that created white sparry dolomite cement in the Manetoe Facies. Remnants of the dolomitizing fluids are present as formation waters in some Devonian formations in Alberta. Subsequent invasion of meteoric waters produced more dilute diagenetic fluids which resulted in the precipitation of calcite and quartz cement in the Manetoe Facies. These fluids are present in fluid inclusions and are responsible for the low {sup 18}O content of the calcite cement. The temperatures of calcite and quartz formation differ as a function of burial depth within the Manetoe Facies during the Mesozoic and Cenozoic, while the temperature of formation for dolomite does not.

  16. Fungal Ferromanganese Mineralisation in Cretaceous Dinosaur Bones from the Gobi Desert, Mongolia.

    Science.gov (United States)

    Owocki, Krzysztof; Kremer, Barbara; Wrzosek, Beata; Królikowska, Agata; Kaźmierczak, Józef

    2016-01-01

    Well-preserved mycelia of fungal- or saprolegnia-like biota mineralised by ferromanganese oxides were found for the first time in long bones of Late Cretaceous dinosaurs from the Gobi Desert (Nemegt Valley, Mongolia). The mycelia formed a biofilm on the wall of the bone marrow cavity and penetrated the osteon channels of the nearby bone tissue. Optical microscopy, Raman, SEM/EDS, SEM/BSE, electron microprobe and cathodoluminescence analyses revealed that the mineralisation of the mycelia proceeded in two stages. The first stage was early post-mortem mineralisation of the hyphae by Fe/Mn-oxide coatings and microconcretions. Probably this proceeded in a mildly acidic to circumneutral environment, predominantly due to heterotrophic bacteria degrading the mycelial necromass and liberating Fe and Mn sorbed by the mycelia during its lifetime. The second stage of mineralisation, which proceeded much later following the final burial of the bones in an alkaline environment, resulted from the massive precipitation of calcite and occasionally barite on the iron/manganese-oxide-coated mycelia. The mineral phases produced by fungal biofilms colonising the interiors of decaying dinosaur bones not only enhance the preservation (fossilisation) of fungal remains but can also be used as indicators of the geochemistry of the dinosaur burial sites.

  17. High Quality, Low Cost Ammonothermal Bulk GaN Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ehrentraut, D; Pakalapati, RT; Kamber, DS; Jiang, WK; Pocius, DW; Downey, BC; McLaurin, M; D' Evelyn, MP

    2013-12-18

    Ammonothermal GaN growth using a novel apparatus has been performed on c-plane, m-plane, and semipolar seed crystals with diameters between 5 mm and 2 in. to thicknesses of 0.5-3 mm. The highest growth rates are greater than 40 mu m/h and rates in the 10-30 mu m/h range are routinely observed for all orientations. These values are 5-100x larger than those achieved by conventional ammonothermal GaN growth. The crystals have been characterized by X-ray diffraction rocking-curve (XRC) analysis, optical and scanning electron microscopy (SEM), cathodoluminescence (CL), optical spectroscopy, and capacitance-voltage measurements. The crystallinity of the grown crystals is similar to or better than that of the seed crystals, with FWHM values of about 20-100 arcsec and dislocation densities of 1 x 10(5)-5 x 10(6) cm(-2). Dislocation densities below 10(4) cm(-2) are observed in laterally-grown crystals. Epitaxial InGaN quantum well structures have been successfully grown on ammonothermal wafers. (C) 2013 The Japan Society of Applied Physics

  18. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    Science.gov (United States)

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-03-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties.

  19. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    Energy Technology Data Exchange (ETDEWEB)

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Rodt, Sven, E-mail: srodt@physik.tu-berlin.de; Reitzenstein, Stephan [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin (Germany); Strittmatter, André [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin (Germany); Otto-von-Guericke Universität Magdeburg, Universitätsplatz 2, D-39106 Magdeburg (Germany)

    2015-07-15

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  20. Structural and optical properties of self-catalytic GaAs:Mn nanowires grown by molecular beam epitaxy on silicon substrates.

    Science.gov (United States)

    Gas, Katarzyna; Sadowski, Janusz; Kasama, Takeshi; Siusys, Aloyzas; Zaleszczyk, Wojciech; Wojciechowski, Tomasz; Morhange, Jean-François; Altintaş, Abdulmenaf; Xu, H Q; Szuszkiewicz, Wojciech

    2013-08-21

    Mn-doped GaAs nanowires were grown in the self-catalytic growth mode on the oxidized Si(100) surface by molecular beam epitaxy and characterized by scanning and transmission electron microscopy, Raman scattering, photoluminescence, cathodoluminescence, and electron transport measurements. The transmission electron microscopy studies evidenced the substantial accumulation of Mn inside the catalyzing Ga droplets on the top of the nanowires. Optical and transport measurements revealed that the limit of the Mn content for self-catalysed growth of GaAs nanowires corresponds to the doping level, i.e., it is much lower than the Mn/Ga flux ratio (about 3%) used during the MBE growth. The resistivity measurements of individual nanowires confirmed that they are conductive, in accordance with the photoluminescence measurements which showed the presence of Mn(2+) acceptors located at Ga sites of the GaAs host lattice of the nanowires. An anomalous temperature dependence of the photoluminescence related to excitons was demonstrated for Mn-doped GaAs nanowires.

  1. Multi-section core-shell InGaN/GaN quantum-well nanorod light-emitting diode array.

    Science.gov (United States)

    Tu, Charng-Gan; Yao, Yu-Feng; Liao, Che-Hao; Su, Chia-Ying; Hsieh, Chieh; Weng, Chi-Ming; Lin, Chun-Han; Chen, Hao-Tsung; Kiang, Yean-Woei; Yang, C C

    2015-08-24

    The growth of a two-section, core-shell, InGaN/GaN quantum-well (QW) nanorod- (NR-) array light-emitting diode device based on a pulsed growth technique with metalorganic chemical vapor deposition is demonstrated. A two-section n-GaN NR is grown through a tapering process for forming two uniform NR sections of different cross-sectional sizes. The cathodoluminescence (CL), photoluminescence (PL), and electrolumines-cence (EL) characterization results of the two-section NR structure are compared with those of a single-section NR sample, which is prepared under the similar condition to that for the first uniform NR section of the two-section sample. All the CL, PL, and EL spectra of the two-section sample (peaked between 520 and 525 nm) are red-shifted from those of the single-section sample (peaked around 490 nm) by >30 nm in wavelength. Also, the emitted spectral widths of the two-section sample become significantly larger than their counterparts of the single-section sample. The PL spectral full-width at half-maximum increases from ~37 to ~61 nm. Such variations are attributed to the higher indium incorporation in the sidewall QWs of the two-section sample due to the stronger strain relaxation in an NR section of a smaller cross-sectional size and the more constituent atom supply from the larger gap volume between neighboring NRs.

  2. Non-destructive analyses on a meteorite fragment that fell in the Madrid city centre in 1896.

    Science.gov (United States)

    Garcia-Guinea, Javier; Tormo, Laura; Rubio Ordoñez, Alvaro; Garcia-Moreno, Olga

    2013-09-30

    The historical Madrid meteorite chondrite fell in 1896 showing thin melt veins with a 65% of brecciated forsterite fragments surrounded by a fine grained matrix formed by troilite, chromite and Fe-Ni blebs. It exhibits a delicate iron infill, neo-formation of troilite in pockets and shock veins and neo-formation of Na-feldspar formed at high temperature and fast quenching. The semi-quantitative mineral determinations were performed with IMAGEJ freeware and chemical mappings resulting in the following approximated compositions: olivine (~55%); augite (~10%); enstatite (~10%); plagioclase (~10%); chromite (~2%); troilite (~4%), kamacite-taenite α-γ-(Fe, Ni) (~7%) and merrillite (~7%). The specimen was also studied by computer tomography, micro-Raman spectroscopy and spectral cathodoluminescence. X-ray diffraction patterns were also recorded in non-destructive way on a polished surface because of the small size of the specimen. This combination of non-destructive techniques provides an improved knowledge on the Madrid-1896 meteorite compared to the previous study performed on the same specimen carried out twenty years ago by electron probe microanalysis and optical microscopy in destructive way. Limits of these techniques are the specimen's size in the analytical chambers and the threshold resolution of the microscopes analyzing shock veins micro-crystals.

  3. Strong light scattering and broadband (UV to IR) photoabsorption in stretchable 3D hybrid architectures based on Aerographite decorated by ZnO nanocrystallites

    Science.gov (United States)

    Tiginyanu, Ion; Ghimpu, Lidia; Gröttrup, Jorit; Postolache, Vitalie; Mecklenburg, Matthias; Stevens-Kalceff, Marion A.; Ursaki, Veaceslav; Payami, Nader; Feidenhansl, Robert; Schulte, Karl; Adelung, Rainer; Mishra, Yogendra Kumar

    2016-09-01

    In present work, the nano- and microscale tetrapods from zinc oxide were integrated on the surface of Aerographite material (as backbone) in carbon-metal oxide hybrid hierarchical network via a simple and single step magnetron sputtering process. The fabricated hybrid networks are characterized for morphology, microstructural and optical properties. The cathodoluminescence investigations revealed interesting luminescence features related to carbon impurities and inherent host defects in zinc oxide. Because of the wide bandgap of zinc oxide and its intrinsic defects, the hybrid network absorbs light in the UV and visible regions, however, this broadband photoabsorption behavior extends to the infrared (IR) region due to the dependence of the optical properties of ZnO architectures upon size and shape of constituent nanostructures and their doping by carbon impurities. Such a phenomenon of broadband photoabsorption ranging from UV to IR for zinc oxide based hybrid materials is novel. Additionally, the fabricated network exhibits strong visible light scattering behavior. The developed Aerographite/nanocrystalline ZnO hybrid network materials, equipped with broadband photoabsorption and strong light scattering, are very promising candidates for optoelectronic technologies.

  4. Integrated single crystal laser ablation U/Pb and (U-Th)/He dating of detrital accessory minerals - Proof-of-concept studies of titanites and zircons from the Fish Canyon tuff

    Science.gov (United States)

    Horne, Alexandra M.; van Soest, Matthijs C.; Hodges, Kip V.; Tripathy-Lang, Alka; Hourigan, Jeremy K.

    2016-04-01

    Excimer laser technologies enable a rapid and effective approach to simultaneous U/Pb geochronology and (U-Th)/He thermochronology of a wide range of detrital accessory minerals. Here we describe the 'laser ablation double dating' (LADD) method and demonstrate its viability by applying it to zircon and titanite crystals from the well-characterized Fish Canyon tuff. We found that LADD dates for Fish Canyon zircon (206Pb/238U - 28.63 ± 0.11 Ma; (U-Th)/He - 28.38 ± 0.73 Ma) are statistically indistinguishable from those obtained through established, traditional methods of single-crystal dating. The same is true for Fish Canyon titanite LADD dates: 206Pb/238U - 28.08 ± 0.90 Ma; (U-Th)/He - 27.98 ± 0.86 Ma. As anticipated, given that LADD involves the analysis of smaller amounts of material than traditional methods, it yields dates with higher analytical uncertainty. However, this does not substantially reduce the utility of the results for most applications to detrital datasets. An important characteristic of LADD is that it encourages the chemical characterization of crystals by backscattered electron, cathodoluminescence, and/or Raman mapping prior to dating. In addition, by permitting the rapid and robust dating of crystals regardless of the degree of their abrasion during sedimentary transport, the method theoretically should yield dates that are more broadly representative of those of the entire population of detrital crystals in a natural sample.

  5. Study of the defects in GaN epitaxial films grown on sapphire by HVPE

    Science.gov (United States)

    Liu, Zhanhui; Xiu, Xiangqian; Chen, Lin; Zhang, Rong; Xie, Zili; Han, Ping; Shi, Yi; Gu, Shulin; Zheng, Youdou

    2008-02-01

    In this paper, the defects in hexagonal GaN epitaxial layers grown on (0001) sapphire (Al IIO 3) substrates by HVPE with a horizontal tube reactor had been studied. The GaN epitaxial layers were etched by means of defect-selective etching (Orthodox etching in molten KOH). The samples were characterized by Scanning Electron Microscopy (SEM) and Cathodoluminescence spectra (CL). From surface morphology and cross-sectional images, the defects could be divided into various types: cracks, low angle grain boundary (LAGB), nano-pipes and dislocations. These different defects were discussed. The cracks were proposed as related to the strain. And the strain could not only come from the lattice mismatch and thermal mismatch between sapphire and GaN layer in their interface, but also from the HVPE growth process. It was found that these screw, mixed and edge type dislocations formed small hexagonal pits after etching. Some pits would be observed in the area near LAGB. Additionally, by CL mapping technique, some non-radiative recombination centers without surface terminations could be probed optically.

  6. Effect of ammonification temperature on the formation of coaxial GaN/Ga2O3 nanowires

    Science.gov (United States)

    Kumar, Mukesh; Sarau, George; Heilmann, Martin; Christiansen, Silke; Kumar, Vikram; Singh, R.

    2017-01-01

    The effect of ammonification temperature on the formation of coaxial GaN/Ga2O3 nanowires from β-Ga2O3 nanowires is reported in this work. High quality wurtzite GaN material showing a single c-plane phase is achieved from β-Ga2O3 nanowires having monoclinic crystal structure at a high ammonification temperature of 1050 °C. Lower ammonification temperatures such as 900 °C are also adequate for achieving coaxial GaN/Ga2O3 nanowire heterostructures, and the degree of GaN phase can be adjusted by varying the ammonification temperature. The crystalline quality of GaN/Ga2O3 nanowires improves with increasing the ammonification temperature. Resonant Raman spectra of GaN/Ga2O3 nanowires show Raman progression through multiple longitudinal-optical-phonon modes with overtones of up to second order. The development and improvement of the emission peak toward the near band edge of GaN at different ammonification temperatures were investigated using cathodoluminescence and photoluminescence characterization.

  7. The role of impurities in the shape, structure and physical properties of semiconducting oxide nanostructures grown by thermal evaporation

    Directory of Open Access Journals (Sweden)

    Teresa Cebriano

    2016-03-01

    Full Text Available A thermal evaporation method developed in the research group enables to grow and design several morphologies of semiconducting oxide nanostructures, such as Ga2O3, GeO2 or Sb2O3, among others, and some ternary oxide compounds (ZnGa2O4, Zn2GeO4. In order to tailor physical properties, a successful doping of these nanostructures is required. However, for nanostructured materials, doping may affect not only their physical properties, but also their morphology during the thermal growth process. In this paper, we will show some examples of how the addition of impurities may result into the formation of complex structures, or changes in the structural phase of the material. In particular, we will consider the addition of Sn and Cr impurities into the precursors used to grow Ga2O3, Zn2GeO4 and Sb2O3 nanowires, nanorods or complex nanostructures, such as crossing wires or hierarchical structures. Structural and optical properties were assessed by electron microscopy (SEM and TEM, confocal microscopy, spatially resolved cathodoluminescence (CL, photoluminescence, and Raman spectroscopies. The growth mechanisms, the luminescence bands and the optical confinement in the obtained oxide nanostructures will be discussed. In particular, some of these nanostructures have been found to be of interest as optical microcavities. These nanomaterials may have applications in optical sensing and energy devices.

  8. Microwave solid state synthesis and luminescence properties of green-emitting Gd2O2S:Tb3+ phosphor

    Science.gov (United States)

    He, Can; Xia, Zhiguo; Liu, Quanlin

    2015-04-01

    Gd2-xO2S:xTb3+ phosphors were prepared by the microwave solid state method, and its phase formation and morphologies were studied by the X-ray powder diffraction (XRD) and scanning electron microscope (SEM) techniques. The photoluminescence (PL) properties, cathodoluminescence (CL) properties and PL thermal stability of the samples were investigated, which indicated that better luminescence properties can be obtained via the microwave method compared to the conventional high temperature solid-state method. The composition-optimized Gd1.85O2S:15%Tb3+ exhibited strong green emission peaking at 546 nm upon excitation at 254 nm with the CIE coordinates of (0.238, 0.382). Different electric voltage and current dependent CL spectra investigations of Gd1.85O2S:15%Tb3+ phosphor shows similar green spectral profile as PL emission and it also demonstrates the good luminescence stability suggesting its potential application as green emission component in cathode ray tube (CRT).

  9. Electron-beam-induced current at absorber back surfaces of Cu(In,Ga)Se{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kavalakkatt, J.; Abou-Ras, D., E-mail: daniel.abou-ras@helmholtz-berlin.de; Nichterwitz, M.; Caballero, R.; Rissom, T.; Unold, T.; Scheer, R.; Schock, H. W. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz. 1, 14109 Berlin (Germany); Haarstrich, J.; Ronning, C. [Institut für Festkörperphysik, Friedrich Schiller Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2014-01-07

    The present work reports on investigations of the influence of the microstructure on electronic properties of Cu(In,Ga)Se{sub 2} (CIGSe) thin-film solar cells. For this purpose, ZnO/CdS/CIGSe stacks of these solar cells were lifted off the Mo-coated glass substrates. The exposed CIGSe backsides of these stacks were investigated by means of electron-beam-induced current (EBIC) and cathodoluminescence (CL) measurements as well as by electron backscattered diffraction (EBSD). EBIC and CL profiles across grain boundaries (GBs), which were identified by EBSD, do not show any significant changes at Σ3 GBs. Across non-Σ3 GBs, on the other hand, the CL signals exhibit local minima with varying peak values, while by means of EBIC, decreased and also increased short-circuit current values are measured. Overall, EBIC and CL signals change across non-Σ3 GBs always differently. This complex situation was found in various CIGSe thin films with different [Ga]/([In]+[Ga]) and [Cu]/([In]+[Ga]) ratios. A part of the EBIC profiles exhibiting reduced signals across non-Σ3 GBs can be approximated by a simple model based on diffusion of generated charge carriers to the GBs.

  10. Electron-beam-induced current at absorber back surfaces of Cu(In,Ga)Se2 thin-film solar cells

    Science.gov (United States)

    Kavalakkatt, J.; Abou-Ras, D.; Haarstrich, J.; Ronning, C.; Nichterwitz, M.; Caballero, R.; Rissom, T.; Unold, T.; Scheer, R.; Schock, H. W.

    2014-01-01

    The present work reports on investigations of the influence of the microstructure on electronic properties of Cu(In,Ga)Se2 (CIGSe) thin-film solar cells. For this purpose, ZnO/CdS/CIGSe stacks of these solar cells were lifted off the Mo-coated glass substrates. The exposed CIGSe backsides of these stacks were investigated by means of electron-beam-induced current (EBIC) and cathodoluminescence (CL) measurements as well as by electron backscattered diffraction (EBSD). EBIC and CL profiles across grain boundaries (GBs), which were identified by EBSD, do not show any significant changes at Σ3 GBs. Across non-Σ3 GBs, on the other hand, the CL signals exhibit local minima with varying peak values, while by means of EBIC, decreased and also increased short-circuit current values are measured. Overall, EBIC and CL signals change across non-Σ3 GBs always differently. This complex situation was found in various CIGSe thin films with different [Ga]/([In]+[Ga]) and [Cu]/([In]+[Ga]) ratios. A part of the EBIC profiles exhibiting reduced signals across non-Σ3 GBs can be approximated by a simple model based on diffusion of generated charge carriers to the GBs.

  11. Amplitude of late Miocene sea-level fluctuations from karst development in reef-slope deposits (SE Spain)

    Science.gov (United States)

    Reolid, Jesús; Betzler, Christian; Braga, Juan Carlos

    2016-11-01

    A prograding late Miocene carbonate platform in southern Spain revealing different sea-level pinning points was analysed with the aim to increase the accuracy of reconstruction of past sea-level changes. These pinning points are distinct diagenetic zones (DZ) and the position of reef-framework deposits. DZ1 is defined by the dissolution of bioclastic components and DZ2 by calcitic cement precipitation in dissolution pores. Calcite cements are granular and radiaxial fibrous, and are of meteoric origin as deduced from cathodoluminescence, EDX spectroscopy, as well as from δ13C and δ18O isotope analyses. DZ3 has moldic porosity after aragonitic bioclasts with minor granular calcitic cements. DZ1 and DZ2 indicate karstification and the development of a coastal palaeoaquifer during a sea-level lowstand. DZ3 diagenetic features are related to the final subaerial exposure of the section during the Messinian Salinity Crisis. Facies and diagenetic data reveal a complete cycle of sea-level fall (23 ± 1 m) and rise (31 ± 1 m). A robust age model based on magneto- and cyclostratigraphy for these deposits places this cycle between 5.89 and 5.87 Ma. Therefore, for the first time, this work allows a direct comparison of an outcrop with a pelagic marine proxy record of a specific Neogene sea-level fluctuation.

  12. Influence of stacking faults on the properties of GaN-based UV light-emitting diodes grown on non-polar substrates

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.Q.; Adivarahan, V.; Shatalov, M.; Gaevski, M.E.; Kuokstis, E.; Yang, J.W.; Maruska, H.P.; Gong, Z.; Asif Khan, M. [Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina (United States); Liu, R.; Bell, A.; Ponce, F.A. [Department of Physics and Astronomy, Arizona State University, Tempe, Arizona (United States)

    2005-05-01

    We report on the reduction of defect densities in non-polar a-plane GaN films over r-plane sapphire achieved by epitaxial laterally overgrowth (ELOG) approach. A mask pattern was used to produce ELOG GaN with wing region width of about 30 {mu}m. Based on transmission electron microscopy (TEM) results, the window regions have stacking faults density of {proportional_to}10{sup 6}cm {sup -1} and threading dislocation density of {proportional_to}10 {sup 10} cm {sup -2}. Both ELOG Ga-face and N-face wing regions have stacking fault density of {proportional_to}10 {sup 5} cm {sup -1}, and dislocation density less than 10 {sup 8} cm {sup -2}. Cathodoluminescence studies reveal the difference in defect densities between N-faced and Ga-faced wings. GaN-based UV light-emitting diode formed on Ga-faced wing shows stronger quantum well emission and weaker parasitic emission than that formed on N-faced wing. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Non-catalyst growth and characterization of a-plane AlGaN nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Gaevski, Mikhail E.; Sun, Wenhong; Yang, Jinwei; Adivarahan, Vinod; Sattu, Ajay; Mokina, Irina; Shatalov, Maxim; Simin, Grigory; Asif Khan, M. [Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2006-05-15

    We report on growth of Al{sub 0.22}Ga{sub 0.78}N/Al{sub 0.06}Ga{sub 0.94}N nanorods over a -plane GaN template using low pressure metal-organic chemical vapor deposition. Nanorods with average diameter of 100 nm were up to 30 {mu}m long. They grew preferentially along the left angle 11 anti 20 right angle crystal direction and possessed excellent optical and mechanical properties. It was shown using monochromatic cathodoluminescence that nanorods emit light both at 320 nm and 350 nm over entire length proving uniform coating of the Al{sub 0.06}Ga{sub 0.94}N rod core by an Al{sub 0.22}Ga{sub 0.78}N shield. The elastic modulus of nanorod material was found to be 185 GPa. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Structural and luminescent properties of europium doped TiO{sub 2} thick films synthesized by the ultrasonic spray pyrolysis technique

    Energy Technology Data Exchange (ETDEWEB)

    Zaleta-Alejandre, E; Zapata-Torres, M; Aguilar-Frutis, M; Alarcon-Flores, G; Guzman-Mendoza, J [Centro de Investigacion en Ciencia Aplicada y TecnologIa Avanzada-IPN, Legaria 694, Col. Irrigacion, Del. Miguel Hidalgo, Mexico D.F. (Mexico); Garcia-Hipolito, M [Instituto de Investigaciones en Materiales-Universidad Nacional Autonoma de Mexico, A.P. 70-360, Coyoacan 04510, Mexico D.F. (Mexico); Falcony, C, E-mail: ezaletaa@ipn.m [Centro de Investigacion y de Estudios Avanzados-IPN, Departamento de Fisica, Apdo. Postal 14-470, Del. Gustavo A. Madero, C.P. 07000, Mexico, D.F. (Mexico)

    2009-05-07

    The structural and luminescent properties of trivalent europium-doped titanium dioxide films synthesized by the ultrasonic spray pyrolysis technique at several substrate temperatures are reported. These films are nanocrystalline and present a mixture of tetragonal (anatase and rutile) crystal structures of the titania as determined by x-ray diffraction. The rutile crystal structure became predominant as the substrate temperature during deposition was increased. Under UV and electron beam excitation, these coatings showed strong luminescence due to f-f transitions and the dominant transition was the hypersensitive {sup 5}D{sub 0} {yields} {sup 7}F{sub 2} red emission of Eu{sup 3+}. The photo- and cathodoluminescence characteristics of these films were studied as a function of growth parameters such as substrate temperature and europium concentration. Excitation with a wavelength of 396 nm resulted in photoluminescent emission peaks located at 557, 580, 592, 615, 652 and 703 nm, associated with the electronic transitions of the Eu{sup 3+} ion. The photoluminescence (PL) intensity as a whole is observed to decrease as the deposition temperature is increased. Also, with increasing doping concentration, a quenching of the PL is observed. The chemical composition and surface morphology characteristics of the films are also reported.

  15. Vibrational and optical spectroscopies integrated with environmental transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Picher, Matthieu; Mazzucco, Stefano [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203 (United States); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20740 (United States); Blankenship, Steve [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203 (United States); Sharma, Renu, E-mail: renu.sharma@nist.gov [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203 (United States)

    2015-03-15

    Here, we present a measurement platform for collecting multiple types of spectroscopy data during high-resolution environmental transmission electron microscopy observations of dynamic processes. Such coupled measurements are made possible by a broadband, high-efficiency, free-space optical system. The critical element of the system is a parabolic mirror, inserted using an independent hollow rod and placed below the sample holder which can focus a light on the sample and/or collect the optical response. We demonstrate the versatility of this optical setup by using it to combine in situ atomic-scale electron microscopy observations with Raman spectroscopy. The Raman data is also used to measure the local temperature of the observed sample area. Other applications include, but are not limited to: cathodo- and photoluminescence spectroscopy, and use of the laser as a local, high-rate heating source. - Highlights: • Broadband, high-efficiency design adaptable to other electron microscopes. • Raman spectroscopy integrated with environmental transmission electron microscopy. • Raman spectra peak frequency shifts enable measurement of local sample temperature. • Multiple types of optical spectroscopy enabled, e.g. cathodoluminescence.

  16. Mineralization of human aortas with coarctation: quantitative electron probe microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Krefting, E.R.; Roehrig, T.; Broecker, W.; Anyanwu, E.; Schlake, W.; Dittrich, H.; Hoehling, H.J.

    1982-01-01

    Aortas with coarctation (isthmus stenosis) are obviously an ideal model to investigate pressure dependent changes of the aorta, as one can compare the proximal region (high pressure) with the distal region (low pressure). 7 aortas of patients aged from 2 months to 54 years were investigated. The concentrations of Na, Mg, P, S, C1, K, and Ca were determined by electronprobe microanalysis. Ca and P are constituent parts of the developing mineral and are mainly discussed. The Ca/P ratio (by weight) is about 0.3 in the unmineralized and about 2 in the mineralized tissue. Mineralization is demonstrated by a parallel increase of Ca, P, and the Ca/P ratio. Enrichments of Ca and P are found above all in a subintimal band. Usually they occur proximally and distally, but are much more pronounced proximally. Even in the aorta of a 2 month old infant enrichments were found proximally, but not distally. Thus mineral deposits occur very early in regions of hypertension. The differences between the proximal and distal region may demonstrate the influence of blood pressure on vascular mineralization. The mineralization starts in small compartments, which increase in size and number in the process of mineralization. Mineralized regions could often be localized by cathodoluminescence. But to demonstrate and localize the initial mineral deposits and to quantify element contents, electronprobe microanalysis became indispensable.

  17. Luminescence spectra of lead tungstate, spodumene and topaz crystals Thermoluminescence

    CERN Document Server

    Ramachandran, V

    2002-01-01

    A detailed set of thermoluminescence, cathodoluminescence and radioluminescence (TL, CLTL and RLTL) data of lead tungstate, Spodumene and Topaz have been reported for the first time over a wide temperature range from 25 to 500K. Lead tungstate (PbWO sub 4), a widely known scintillating material, gives TL glow peaks which are related to complex defect centres. Doping of this crystal with trivalent rare earth ions (La sup 3 sup + , Y sup 3 sup +) reduces the slow component of the emission thereby making it more suitable for its applications. The pentavalent dopants on the other hand, enhance the green emission and quench the blue emission at temperatures 100K. The origin and the irradiation temperature definitely have an effect on the spectrum. No strong relationship could be derived from the dose dependence data. Two less studied minerals, Spodumene and Topaz have also been investigated with the luminescence techniques. The glow peak near 250degC is thought to have originated from Mn sup 2 sup + centres. As th...

  18. The origin of 2.7 eV luminescence and 5.2 eV excitation band in hafnium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Perevalov, T. V., E-mail: timson@isp.nsc.ru [A. V. Rzhanov Institute of Semiconductor Physics of SB RAS, 13 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk (Russian Federation); Aliev, V. Sh.; Gritsenko, V. A. [A. V. Rzhanov Institute of Semiconductor Physics of SB RAS, 13 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Saraev, A. A. [Boreskov Institute of Catalysis of SB RAS, 5 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Kaichev, V. V. [Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk (Russian Federation); Boreskov Institute of Catalysis of SB RAS, 5 Lavrentieva Ave, 630090 Novosibirsk (Russian Federation); Ivanova, E. V.; Zamoryanskaya, M. V. [Ioffe Physicotechnical Institute of RAS, 26 Politechnicheskaya St., 194021 St. Petersburg (Russian Federation)

    2014-02-17

    The origin of a blue luminescence band at 2.7 eV and a luminescence excitation band at 5.2 eV of hafnia has been studied in stoichiometric and non-stoichiometric hafnium oxide films. Experimental and calculated results from the first principles valence band spectra showed that the stoichiometry violation leads to the formation of the peak density of states in the band gap caused by oxygen vacancies. Cathodoluminescence in the non-stoichiometric film exhibits a band at 2.65 eV that is excited at the energy of 5.2 eV. The optical absorption spectrum calculated for the cubic phase of HfO{sub 2} with oxygen vacancies shows a peak at 5.3 eV. Thus, it could be concluded that the blue luminescence band at 2.7 eV and HfO{sub x} excitation peak at 5.2 eV are due to oxygen vacancies. The thermal trap energy in hafnia was estimated.

  19. Authigenetic K—feldspars and Their Relations to Sn—polymetallic Mineralization in the Dachang Ore Field

    Institute of Scientific and Technical Information of China (English)

    潘家华; G.C.AMSTUTZ

    1993-01-01

    Sn-polymetallic ores at Dachang,Guangxi Autonomous Region,China,are hosted in Middle-Upper Devonian reef limestones,siliceous rocks,banded and lenticular limestones,etc.Two types of orebodies can be distinguished according to their telations to the bedding:one is distributed along the bedding and the.other cuts across the bedding.Sn and sulfide orebodies associated with K-feldspare are mostly characterized by laminated ore structure. Microscopic examinations of K-feldspar-bearing rocks,in conjunction with X-ray diffraction,chemical composiion and cathodoluminescence data for K-feldspars,as well as their telations to mineralization,the authors consider that the K-feldspare are of authigenic origin,subordinate to the epigenetic stage of diagenesis,They resulted from the reaction of mixed,deep-seated,circulating underground hot waters rich in K,Al and Si with argillaceous carbonates during the Indo nesian orogenic movement.It is suggested more attention should be paid to the effect of authigenic K-feldspars on Sn mineralization.In the meantime the event related to circulating underground hot waters should also be taken into account so as to provide new clues to blind ore prospecting.

  20. U-Pb SHRIMP Dating of Zircon from Quartz Veins of the Yangshan Gold Deposit in Gansu Province and Its Geological Significance

    Institute of Scientific and Technical Information of China (English)

    QI Jinzhong; YUAN Shisong; LIU Zhijie; LIU Dunyi; WANG Yanbin; LI Zhihong; GUO Junhua; SUN Bin3

    2004-01-01

    The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±l.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.

  1. SIMS U-Pb zircon age of a tuff layer in the Meishucun section, Yunnan, southwest China: Constraint on the age of the Precambrian-Cambrian boundary

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Determination of the age of the Precambrian-Cambrian boundary is critical in understanding early evolution of life on Earth. SIMS U-Pb zircon analyses of the Bed 5 tuff layer of the Meishucun section were carried out closely following the guidance of cathodoluminescence images, and the majority of analyses were conducted on the oscillatory zircon grains. Thirteen measurements yield a highly reliable Concordia U-Pb age of 536.7 ± 3.9 Ma for the Bed 5 horizon. A grand mean of 206Pb/238U age of 535.2± 1.7 Ma (MSWD = 0.53) is calculated based on 13 concordant SIMS measurements of this study and 4 nano-SIMS measurements of Sawaki et al., which is the best estimate of the deposition age of the tuff layer within Bed 5 in the Meishucun section. This age has provided a robust age constraint on the significant Precambrian-Cambrian boundary strata in southern China, which independently suggested the placement of the Precambrian-Cambrian boundary at the bottom of the Xiaowaitoushan Member (Marker A).

  2. Recombination by grain-boundary type in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John, E-mail: john.moseley@nrel.gov; Ahrenkiel, Richard K. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401 (United States); Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401 (United States); Metzger, Wyatt K.; Moutinho, Helio R.; Guthrey, Harvey L.; Al-Jassim, Mowafak M. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401 (United States); Paudel, Naba; Yan, Yanfa [Department of Physics & Astronomy, University of Toledo, Toledo, Ohio 43606 (United States)

    2015-07-14

    We conducted cathodoluminescence (CL) spectrum imaging and electron backscatter diffraction on the same microscopic areas of CdTe thin films to correlate grain-boundary (GB) recombination by GB “type.” We examined misorientation-based GB types, including coincident site lattice (CSL) Σ = 3, other-CSL (Σ = 5–49), and general GBs (Σ > 49), which make up ∼47%–48%, ∼6%–8%, and ∼44%–47%, respectively, of the GB length at the film back surfaces. Statistically averaged CL total intensities were calculated for each GB type from sample sizes of ≥97 GBs per type and were compared to the average grain-interior CL intensity. We find that only ∼16%–18% of Σ = 3 GBs are active non-radiative recombination centers. In contrast, all other-CSL and general GBs are observed to be strong non-radiative centers and, interestingly, these GB types have about the same CL intensity. Both as-deposited and CdCl{sub 2}-treated films were studied. The CdCl{sub 2} treatment reduces non-radiative recombination at both other-CSL and general GBs, but GBs are still recombination centers after the CdCl{sub 2} treatment.

  3. Effect of Au/SiO2 substrate on the structural and optical properties of gallium nitride grown by CVD

    Indian Academy of Sciences (India)

    A Ramos-Carrazco; R Garcia-Gutierrez; M Barboza-Flores; R Rangel; O E Contreras; D Berman-Mendoza

    2014-12-01

    The improvement of the growth of thick GaN films using a fused silica wafer covered with a thin gold layer by chemical vapour deposition at 800 °C is reported. In order to compare the surface properties, crystalline quality, micromilling performance and luminescence, the characterization of a GaN film grown on a silicon wafer is presented as well. The different morphologies of the surface observed on the GaN films are compared on each substrate and the resulting microstructures are presented in detail. High resolution TEM images of the GaN films show the main crystallographic planes characterizing these structures. The wurtzite structure was determined for each sample using the substrates of Au/SiO2 and Si (100) from the XRD patterns. Also, the re-deposition effect after ion milling of the GaN films is reported. The performance of ionic beam on the surface of the GaN thick films for the geometries patterning of rectangular, circular and annular with two different ion doses was compared. Cathodoluminescence spectra showed that the top surfaces of the samples emit strong UV emissions peaked at 3.35 and 3.32 eV which are related to the Y4 and Y6 transitions.

  4. Facile synthesis of core/shell ZnO/ZnS nanofibers by electrospinning and gas-phase sulfidation for biosensor applications.

    Science.gov (United States)

    Baranowska-Korczyc, Anna; Sobczak, Kamil; Dłużewski, Piotr; Reszka, Anna; Kowalski, Bogdan J; Kłopotowski, Łukasz; Elbaum, Danek; Fronc, Krzysztof

    2015-10-07

    This study describes a new method of passivating ZnO nanofiber-based devices with a ZnS layer. This one-step process was carried out in H2S gas at room temperature, and resulted in the formation of core/shell ZnO/ZnS nanofibers. This study presents the structural, optical and electrical properties of ZnO/ZnS nanofibers formed by a 2 nm ZnS sphalerite crystal shell covering a 5 nm ZnO wurtzite crystal core. The passivation process prevented free carriers from capture by oxygen molecules and significantly reduced the impact of O2 on nanostructure conductivity. The conductivity of the nanofibers was increased by three orders of magnitude after the sulfidation, the photoresponse time was reduced from 1500 s to 30 s, and the cathodoluminescence intensity increased with the sulfidation time thanks to the removal of ZnO surface defects by passivation. The ZnO/ZnS nanofibers were stable in water for over 30 days, and in phosphate buffers of acidic, neutral and alkaline pH for over 3 days. The by-products of the passivation process did not affect the conductivity of the devices. The potential of ZnO/ZnS nanofibers for protein biosensing is demonstrated using biotin and streptavidin as a model system. The presented ZnS shell preparation method can facilitate the construction of future sensors and protects the ZnO surface from dissolving in a biological environment.

  5. Optical and Structural Properties of Microcrystalline GaN on an Amorphous Substrate Prepared by a Combination of Molecular Beam Epitaxy and Metal-Organic Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Min, Jung-Wook; Hwang, Hyeong-Yong; Kang, Eun-Kyu; Park, Kwangwook; Kim, Ci-Hyun; Lee, Dong-Seon; Jho, Young-Dahl; Bae, Si-Young; Lee, Yong-Tak

    2016-05-01

    Microscale platelet-shaped GaN grains were grown on amorphous substrates by a combined epitaxial growth method of molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD). First, MBE GaN was grown on an amorphous substrate as a pre-orienting layer and its structural properties were investigated. Second, MOCVD grown GaN samples using the different growth techniques of planar and selective area growth (SAG) were comparatively investigated by transmission electron microscopy (TEM), cathodoluminescence (CL), and photoluminescence (PL). In MOCVD planar GaN, strong bound exciton peaks dominated despite the high density of the threading dislocations (TDs). In MOCVD SAG GaN, on the other hand, TDs were clearly reduced with bending, but basal stacking fault (BSF) PL peaks were observed at 3.42 eV. The combined epitaxial method not only provides a deep understanding of the growth behavior but also suggests an alternative approach for the growth of GaN on amorphous substances.

  6. The luminescence of sapphire subjected to the irradiation of energetic hydrogen and helium ions

    Energy Technology Data Exchange (ETDEWEB)

    Jardin, C.; Canut, B.; Ramos, S.M.M. [Lyon-1 Univ., 69 - Villeurbanne (France)

    1996-08-14

    The luminescence of {alpha}-Al{sub 2}O{sub 3} during He{sup +} and H{sup +} irradiation was measured in the 190-820 nm wavelength range. The luminescence evolution with the ion fluence exhibits two behaviours: (i) at low fluence, the amount of F{sup +} centres increases; (ii) at high fluences, these defects are completely (F centres) or partially (F{sup +} centres) annihilated. This phenomenon results from two concomittant mechanisms: a conversion between F and F{sup +} defects and a destruction of both luminescent species resulting from the radiation-induced damage. By using a simple model we have determined the cross sections associated with creation ({sigma}{sub c}) and annihilation ({sigma}{sub a}) of the F{sup +} centres. The irradiated samples were also investigated by cathodoluminescence and Auger electron spectroscopy. A higher concentration of structural defects and F{sup +} centres is evidenced at the sample area previously irradiated by ions, leading to an unsteady regime of the surface potential under electron excitation. (author).

  7. Vertically Oriented Growth of GaN Nanorods on Si Using Graphene as an Atomically Thin Buffer Layer.

    Science.gov (United States)

    Heilmann, Martin; Munshi, A Mazid; Sarau, George; Göbelt, Manuela; Tessarek, Christian; Fauske, Vidar T; van Helvoort, Antonius T J; Yang, Jianfeng; Latzel, Michael; Hoffmann, Björn; Conibeer, Gavin; Weman, Helge; Christiansen, Silke

    2016-06-01

    The monolithic integration of wurtzite GaN on Si via metal-organic vapor phase epitaxy is strongly hampered by lattice and thermal mismatch as well as meltback etching. This study presents single-layer graphene as an atomically thin buffer layer for c-axis-oriented growth of vertically aligned GaN nanorods mediated by nanometer-sized AlGaN nucleation islands. Nanostructures of similar morphology are demonstrated on graphene-covered Si(111) as well as Si(100). High crystal and optical quality of the nanorods are evidenced through scanning transmission electron microscopy, micro-Raman, and cathodoluminescence measurements supported by finite-difference time-domain simulations. Current-voltage characteristics revealed high vertical conduction of the as-grown GaN nanorods through the Si substrates. These findings are substantial to advance the integration of GaN-based devices on any substrates of choice that sustains the GaN growth temperatures, thereby permitting novel designs of GaN-based heterojunction device concepts.

  8. Spatially resolved and orientation dependent Raman mapping of epitaxial lateral overgrowth nonpolar a-plane GaN on r-plane sapphire.

    Science.gov (United States)

    Jiang, Teng; Xu, Sheng-Rui; Zhang, Jin-Cheng; Xie, Yong; Hao, Yue

    2016-01-01

    Uncoalesced a-plane GaN epitaxial lateral overgrowth (ELO) structures have been synthesized along two mask stripe orientations on a-plane GaN template by MOCVD. The morphology of two ELO GaN structures is performed by Scanning electronic microscopy. The anisotropy of crystalline quality and stress are investigated by micro-Raman spectroscopy. According to the Raman mapping spectra, the variations on the intensity, peak shift and the full width at half maximum (FWHM) of GaN E2 (high) peak indicate that the crystalline quality improvement occurs in the window region of the GaN stripes along [0001], which is caused by the dislocations bending towards the sidewalls. Conversely, the wing regions have better quality with less stress as the dislocations propagated upwards when the GaN stripes are along []. Spatial cathodoluminescence mapping results further support the explanation for the different dislocation growth mechanisms in the ELO processes with two different mask stripe orientations.

  9. Excitonic recombinations in h-BN: From bulk to exfoliated layers

    Science.gov (United States)

    Pierret, A.; Loayza, J.; Berini, B.; Betz, A.; Plaçais, B.; Ducastelle, F.; Barjon, J.; Loiseau, A.

    2014-01-01

    Hexagonal boron nitride (h-BN) and graphite are structurally similar but with very different properties. Their combination in graphene-based devices is now of intense research focus, and it becomes particularly important to evaluate the role played by crystalline defects on their properties. In this paper, the cathodoluminescence (CL) properties of hexagonal boron nitride crystallites are reported and compared to those of nanosheets mechanically exfoliated from them. First, the link between the presence of structural defects and the recombination intensity of trapped excitons, the so-called D series, is confirmed. Low defective h-BN regions are further evidenced by CL spectral mapping (hyperspectral imaging), allowing us to observe new features in the near-band-edge region, tentatively attributed to phonon replicas of exciton recombinations. Second, the h-BN thickness was reduced down to six atomic layers, using mechanical exfoliation, as evidenced by atomic force microscopy. Even at these low thicknesses, the luminescence remains intense and exciton recombination energies are not strongly modified with respect to the bulk, as expected from theoretical calculations, indicating extremely compact excitons in h-BN.

  10. Magneto-optical spectroscopy of (Ga,Mn)N epilayers

    Science.gov (United States)

    Marcet, S.; Ferrand, D.; Halley, D.; Kuroda, S.; Mariette, H.; Gheeraert, E.; Teran, F. J.; Sadowski, M. L.; Galera, R. M.; Cibert, J.

    2006-09-01

    We report on the magneto-optical spectroscopy and cathodoluminescence of a set of wurtzite (Ga,Mn)N epilayers with a low Mn content, grown by molecular-beam epitaxy. The sharpness of the absorption lines associated with the Mn3+ internal transitions allows a precise study of its Zeeman effect in both Faraday and Voigt configurations. We obtain a good agreement if we assume a dynamical Jahn-Teller effect in the 3d4 configuration of Mn, and we determine the parameters of the effective Hamiltonians describing the T25 and E5 levels, and those of the spin Hamiltonian in the ground spin multiplet, from which the magnetization of the isolated ion can be calculated. On layers grown on transparent substrates, transmission close to the band gap, and the associated magnetic circular dichroism, reveal the presence of the giant Zeeman effect resulting from exchange interactions between the Mn3+ ions and the carriers. The spin-hole interaction is found to be ferromagnetic.

  11. Composition and spectra of copper-carotenoid sediments from a pyrite mine stream in Spain

    Science.gov (United States)

    Garcia-Guinea, Javier; Furio, Marta; Sanchez-Moral, Sergio; Jurado, Valme; Correcher, Virgilio; Saiz-Jimenez, Cesareo

    2015-01-01

    Mine drainages of La Poderosa (El Campillo, Huelva, Spain), located in the Rio Tinto Basin (Iberian Pyrite Belt) generate carotenoid complexes mixed with copper sulfates presenting good natural models for the production of carotenoids from microorganisms. The environmental conditions of Rio Tinto Basin include important environmental stresses to force the microorganisms to accumulate carotenoids. Here we show as carotenoid compounds in sediments can be analyzed directly in the solid state by Raman and Luminescence spectroscopy techniques to identify solid carotenoid, avoiding dissolution and pre-concentration treatments, since the hydrous copper-salted paragenesis do not mask the Raman emission of carotenoids. Raman spectra recorded from one of these specimens' exhibit major features at approximately 1006, 1154, and 1520 cm-1. The bands at 1520 cm-1 and 1154 cm-1 can be assigned to in-phase Cdbnd C (γ-1) and Csbnd C stretching (γ-2) vibrations of the polyene chain in carotenoids. The in-plane rocking deformations of CH3 groups linked to this chain coupled with Csbnd C bonds are observed in the 1006 cm-1 region. X-irradiation pretreatments enhance the cathodoluminescence spectra emission of carotenoids enough to distinguish organic compounds including hydroxyl and carboxyl groups. Carotenoids in copper-sulfates could be used as biomarkers and useful proxies for understanding remote mineral formations as well as for terrestrial environmental investigations related to mine drainage contamination including biological activity and photo-oxidation processes.

  12. Luminescent properties of aluminum hydride

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A.P.; Gabis, I.E.; Dmitriev, V.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Dobrotvorskii, M.A., E-mail: mstislavd@gmail.com [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Kuznetsov, V.G. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Matveeva, O.P. [National Mineral Resources University, Saint Petersburg 199106 (Russian Federation); Titov, S.A. [Petersburg State University of Railway Transport, Saint-Petersburg 190031 (Russian Federation); Voyt, A.P.; Elets, D.I. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation)

    2015-10-15

    We studied cathodoluminescence and photoluminescence of α-AlH{sub 3}– a likely candidate for use as possible hydrogen carrier in hydrogen-fueled vehicles. Luminescence properties of original α-AlH{sub 3} and α-AlH{sub 3} irradiated with ultraviolet were compared. The latter procedure leads to activation of thermal decomposition of α-AlH{sub 3} and thus has a practical implementation. We showed that the original and UV-modified aluminum hydride contain luminescence centers ‐ structural defects of the same type, presumably hydrogen vacancies, characterized by a single set of characteristic bands of radiation. The observed luminescence is the result of radiative intracenter relaxation of the luminescence center (hydrogen vacancy) excited by electrons or photons, and its intensity is defined by the concentration of vacancies, and the area of their possible excitation. UV-activation of the dehydrogenation process of aluminum hydride leads to changes in the spatial distribution of the luminescence centers. For short times of exposure their concentration increases mainly in the surface regions of the crystals. At high exposures, this process extends to the bulk of the aluminum hydride and ends with a decrease in concentration of luminescence centers in the surface region. - Highlights: • Aluminum hydride contains hydrogen vacancies which serve as luminescence centers. • The luminescence is the result of radiative relaxation of excited centers. • Hydride UV-irradiation alters distribution and concentration of luminescence centers.

  13. Pre-eruption recharge of the Bishop magma system

    Science.gov (United States)

    Wark, D.A.; Hildreth, W.; Spear, F.S.; Cherniak, D.J.; Watson, E.B.

    2007-01-01

    The 650 km3 rhyolitic Bishop Tuff (eastern California, USA), which is stratigraphically zoned with respect to temperatures of mineral equilibration, reflects a corresponding thermal gradient in the source magma chamber. Consistent with previous work, application of the new TitaniQ (Ti-in-quartz) thermometer to quartz phenocryst rims documents an ???100 ??C temperature increase with chamber depth at the time of eruption. Application of TitaniQ to quartz phenocryst cores, however, reveals lower temperatures and an earlier gradient that was less steep, with temperature increasing with depth by only ???30 ??C. In many late-erupted crystals, sharp boundaries that separate low-temperature cores from high-temperature rims cut internal cathodoluminescent growth zoning, indicating partial phenocryst dissolution prior to crystallization of the high-temperature rims. Rimward jumps in Ti concentration across these boundaries are too abrupt (e.g., 40 ppm across a distance of <10 ??m) to have survived magmatic temperatures for more than ???100 yr. We interpret these observations to indicate heating-induced partial dissolution of quartz, followed by growth of high-temperature rims (made possible by lowering of water activity due to addition of CO2) within 100 yr of the climactic 760 ka eruption. Hot mafic melts injected into deeper parts of the magma system were the likely source of heat and CO2, raising the possibility that eruption and caldera collapse owe their origin to a recharge event. ?? 2007 Geological Society of America.

  14. Sedimentary and diagenetic processes at the origin of chlorites formation inside silico-clastic reservoirs; Processus sedimentaires et diagenetiques a l'origine de la formation des chlorites dans les reservoirs silicoclastiques

    Energy Technology Data Exchange (ETDEWEB)

    Tinseau, E.

    2002-06-01

    Diagenetic chlorite in deeply buried petroleum reservoirs give to the formations relatively good reservoir properties. The purpose of this study is, by a multidisciplinary approach, to better understand how chlorites form and to put into evidence the factors which influence their formation. Four case studies have been chosen: the silici-clastic Mulichinco (Valanginian) and Tordillo (Kimmeridgian) formations of the Neuquen basin, Argentina, the Springhill Formation (Lower Cretaceous) of the Austral basin, Argentina, and the Mashirah Bay formation (Precambrian) from the Huqf-Haushi area, Oman. Sedimentological analyses have been combined to petrographical observations (optical microscope, SEM, TEM, HRTEM, Cathodoluminescence), to chemical analyses, to chlorite polytypicism study, and by fluid inclusions micro-thermometry in silicifications. These studies have allowed to precise the diagenetic sequence for each of these formations and to approach the conditions for the formation of diagenetic chlorites for each case, and to conclude the following points: (1) ferro-magnesian chlorites require precursor material such as volcano-clasts. Their presence is associated with continental environments. Their destabilization into chlorite, via smectite, is favoured at the water/sediment interface during marine transgression. (2) ferriferous chlorites formation can happen from glauconitic minerals which contain a 7 angstroms phase like berthierite, and 10-12 angstroms phase as smectite phase, under anoxic conditions. (3) polytypicism variations traduce two different mechanisms for the chlorite formation: ferro-magnesian chlorites form by dissolution-recrystallization process and re-equilibrate with burial, whereas ferriferous chlorite form from berthierite. (author)

  15. Opto-Electronic Characterization CdTe Solar Cells from TCO to Back Contact with Nano-Scale CL Probe

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John; Al-Jassim, Mowafak M.; Paudel, Naba; Mahabaduge, Hasitha; Kuciauskas, Darius; Guthrey, Harvey L.; Duenow, Joel; Yan, Yanfa; Metzger, Wyatt K.; Ahrenkiel, Richard K.

    2015-06-14

    We used cathodoluminescence (CL) (spectrum-per-pixel) imaging on beveled CdTe solar cell sections to investigate the opto-electronic properties of these devices from the TCO to the back contact. We used a nano-scale CL probe to resolve luminescence from grain boundary (GB) and grain interior (GI) locations near the CdS/CdTe interface where the grains are very small. As-deposited, CdCl2-treated, Cu-treated, and (CdCl2+Cu)-treated cells were analyzed. Color-coded CL spectrum imaging maps on bevels illustrate the distribution of the T=6 K luminescence transitions through the depth of devices with unprecedented spatial resolution. The CL at the GBs and GIs is shown to vary significantly from the front to the back of devices and is a sensitive function of processing. Supporting D-SIMS depth profile, TRPL lifetime, and C-V measurements are used to link the CL data to the J-V performance of devices.

  16. Properties and behavior of quartz for the silicon process

    Energy Technology Data Exchange (ETDEWEB)

    Aasly, Kurt

    2008-07-01

    fluorescence light microscopy of polished thin sections, cathodoluminescence microscopy and spectroscopy and x-ray diffraction. Combining high-temperature microthermometry and shock-heating investigations has proved to provide useful knowledge about the effects of high temperatures on quartz. Results from earlier research have been confirmed showing that mica is the cause of the effects seen in the temperature interval 900 - 1000 degrees Celsius. This has been shown by the total absence of tridimite in the samples and the fact that mica has been seen in the unheated reference samples. Cathodoluminescence microscopy and spectroscopy was used to investigate sample from shock-heating experiments and corresponding reference samples. These investigations show that cathodoluminescence is a useful tool for petrographic investigations of quartz. The shock-heated samples showed a significant change in cathodoluminescence characteristics that need to be investigated further to understand the cause of these changes. A spotted red luminescence was seen in two of the samples indicating the formation of cristobalite or the transition phase within these samples. Cristobalite has been shown in samples after heating to different temperatures in the interval 1250 to 1550 degrees Celsius, although in different amount in the different types of quartz. However, the transformation rates seem to be more similar after prolonged heating at the highest temperature. Experiments also indicate that the quartzcristobalite transformation may be a cause of the disintegration of quartz at high temperatures. This is related to the severe volume expansion as the quartz transforms to cristobalite via the amorphous intermediate transition phase. The last paper presented in the thesis presents investigations of two furnaces that have been producing ferrosilicon and silicon metal respectively. The results from these investigations show that cristobalite is formed relatively rapidly inside the furnace, however

  17. Chemical Environment of Unusually Ge- and Pb-Rich Willemite, Tres Marias Mine, Mexico

    Directory of Open Access Journals (Sweden)

    Bernhardt Saini-Eidukat

    2016-03-01

    Full Text Available The Tres Marias carbonate-hosted Zn-Ge deposit in Chihuahua, Mexico contains willemite [Zn2SiO4] with unusually high concentrations of minor and trace elements (e.g., Pb, Ge, As, P, V; Pb concentrations are as high as 2 wt %, and Ge may reach 4000 ppm (average 900 ppm. Electron microprobe analyses and synchrotron X-ray fluorescence maps show that Zn and Ge, as well as Zn and Pb are negatively correlated, whereas Ge and Pb are positively correlated across zoned willemite crystals. In cathodoluminescence (CL images, those areas of willemite having high trace element concentrations have no, or low CL intensities, whereas zones low in trace elements (except for P display bright blue CL colors. X-ray absorption fine structure (XAFS spectroscopy was used to characterize the chemical nature of Ge and Pb in willemite. Comparisons to reference spectra of natural and artificial substances points to the presence of Ge4+ and Pb2+ in Tres Marias willemite. No evidence for Pb4+ was detected. Oscillatory zonation reflects trace element incorporation into willemite from the oxidation of primary Ge-bearing sphalerite and galena (PbS by siliceous aqueous fluids.

  18. Scattering behaviour of a two-dimensional electron gas induced by Al composition fluctuation in AlxGa1-xN barriers in AlxGa1-xN/GaN heterostructures

    Institute of Scientific and Technical Information of China (English)

    Wang Yan; Shen Bo; Xu Fu-Jun; Huang Sen; Miao Zhen-Lin; Lin Fang; Yang Zhi-Jian; Zhang Guo-Yi

    2009-01-01

    This paper reports that cathodoluminescence (CL) measurements have been done to study the alloy fluctuation of the Al0.3Ca0.7N layer in Al0.3Ca0.7N/GaN heterostructures. The CL images and linescanning results demonstrate the existcnce of compositional fluctuation of Al in the Al0.3Ga0.7N barrier. A model using a δ-shape perturbation Hamilton function has been proposed to simulate the scattering probability of the two dimensional electron gases (2DEG) induced by Al composition fluctuation. Two factors, including conduction band fluctuation and polarization electric field variation, induced by the Al composition fluctuation have been taken into account. The scattering relaxation time induced by both factors has been estimated to be 0.31 ns and 0.0078 us, respectively, indicating that the variation of the piezoelectric field is dominant in the scattering of the 2DEG induced by Al fluctuation.

  19. Improvement of doping efficiency in Mg-Al0.14Ga0.86N/GaN superlattices with AlN interlayer by suppressing donor-like defects

    Institute of Scientific and Technical Information of China (English)

    Liu Ning-Yang; Chen Wei-Hua; Hu Xiao-Dong; Liu Lei; Wang Lei; Yang Wei; Li Ding; Li Lei; Cao Wen-Yu; Lu Ci-Mang; Wan Cheng-Hao

    2012-01-01

    We investigate the mechanism for the improvement of p-type doping efficiency in Mg-Al0.14Gao.86N/GaN superlattices (SLs).It is shown that the hole concentration of SLs increases by nearly an order of magnitude,from 1.1 × 1017to 9.3×1017 cm-3,when an AlN interlayer is inserted to modulate the strains.Schr(o)dinger-Poisson self-consistent calculations suggest that such an increase could be attributed to the reduction of donor-like defects caused by the strain modulation induced by the AlN interlayer.Additionally,the donor-acceptor pair emission exhibits a remarkable decrease in intensity of the cathodoluminescence spectrum for SLs with an AlN interlayer.This supports the theoretical calculations and indicates that the strain modulation of SLs could be beneficial to the donor-like defect suppression as well as the p-type doping efficiency improvement.

  20. Power-law Scaling of Fracture Aperture Sizes in Otherwise-Undeformed Foreland Basin Sandstone: An Example From the Cozzette Sandstone, Piceance Basin, Colorado

    Science.gov (United States)

    Hooker, J. N.; Gale, J. F.; Laubach, S. E.; Gomez, L. A.; Marrett, R.; Reed, R. M.

    2007-12-01

    Power-law variation of aperture size with cumulative frequency has been documented in vein arrays, but such patterns have not been conclusively demonstrated from open or incompletely mineralized opening-mode fractures (joints) in otherwise-undeformed sedimentary rocks. We used subhorizontal core from the nearly flat- lying Cretaceous Cozzette Sandstone, Piceance Basin, Colorado, to document fracture aperture sizes over five orders of magnitude. We measured microfractures (0.0004-0.1164 mm in aperture) along a 276-mm-long scanline using scanning electron microscope-based cathodoluminescence; we measured macrofractures (0.5- 2.15 mm in aperture) in 35 m of approximately horizontal core cut normal to fracture strike. Microfractures are typically filled with quartz. Macrofractures are mostly open and resemble non-mineralized joints, except for thin veneers of quartz cement lining their walls. Micro- and macrofractures share both a common orientation and the same timing with respect to diagenetic sequence, only differing in size and the degree to which they are filled with quartz cement. Power-law scaling equations were derived by fitting trendlines to aperture vs. cumulative frequency data for the microfractures. These equations successfully predicted the cumulative frequencies of the macrofractures, accurate to within a factor of four in each test and within a factor of two in 75 percent of tests. Our results show that tectonic deformation is not prerequisite for power-law scaling of fractures, but instead suggest that scaling emerges from fracture interaction during propagation.

  1. Core-shell GaN-ZnO moth-eye nanostructure arrays grown on a-SiO2/Si (1 1 1) as a basis for improved InGaN-based photovoltaics and LEDs

    Science.gov (United States)

    Rogers, D. J.; Sandana, V. E.; Gautier, S.; Moudakir, T.; Abid, M.; Ougazzaden, A.; Teherani, F. Hosseini; Bove, P.; Molinari, M.; Troyon, M.; Peres, M.; Soares, Manuel J.; Neves, A. J.; Monteiro, T.; McGrouther, D.; Chapman, J. N.; Drouhin, H.-J.; McClintock, R.; Razeghi, M.

    2015-06-01

    Self-forming, vertically-aligned, ZnO moth-eye-like nanoarrays were grown by catalyst-free pulsed laser deposition on a-SiO2/Si (1 1 1) substrates. X-Ray Diffraction (XRD) and Cathodoluminescence (CL) studies indicated that nanostructures were highly c-axis oriented wurtzite ZnO with strong near band edge emission. The nanostructures were used as templates for the growth of non-polar GaN by metal organic vapor phase epitaxy. XRD, scanning electron microscopy, energy dispersive X-ray microanalysis and CL revealed ZnO encapsulated with GaN, without evidence of ZnO back-etching. XRD showed compressive epitaxial strain in the GaN, which is conducive to stabilization of the higher indium contents required for more efficient green light emitting diode (LED) and photovoltaic (PV) operation. Angular-dependent specular reflection measurements showed a relative reflectance of less than 1% over the wavelength range of 400-720 nm at all angles up to 60°. The superior black-body performance of this moth-eye-like structure would boost LED light extraction and PV anti-reflection performance compared with existing planar or nanowire LED and PV morphologies. The enhancement in core conductivity, provided by the ZnO, would also improve current distribution and increase the effective junction area compared with nanowire devices based solely on GaN.

  2. Characterisation of irradiation damage and dopant distribution in synthetic diamonds by luminescence micro-spectroscopy

    CERN Document Server

    Charles, S J

    2002-01-01

    ground and two excited states. The lower energy excited state has a slow rate of decay and the second, higher energy excited state, which is thermally populated, has a high rate of decay to the ground state. The higher energy excited state has a spectrum with a local mode and the centre is metastably enhanced by exposure to UV light. DBI is not dependent on the isotope of boron used to elope the diamonds. The lines at 650.2 nm and 667.8 nm also come from the same centre as each other, designated DB2. The CVD B-doped diamond samples showed changes in boron level by approximately an order of magnitude on scales smaller than 5 mu m. These differences in boron level are due to different surface facet orientations of the grains that comprise the sample, and different facets have different rates of uptake of boron during growth. A simple, qualitative, way of showing the differences in boron level has been shown by using cathodoluminescence (CL) topography, which agrees with results from UV CL spectroscopy. Raman sp...

  3. Characteristics of GaN-based light emitting diodes with different thicknesses of buffer layer grown by HVPE and MOCVD

    Science.gov (United States)

    Tian, Pengfei; Edwards, Paul R.; Wallace, Michael J.; Martin, Robert W.; McKendry, Jonathan J. D.; Gu, Erdan; Dawson, Martin D.; Qiu, Zhi-Jun; Jia, Chuanyu; Chen, Zhizhong; Zhang, Guoyi; Zheng, Lirong; Liu, Ran

    2017-02-01

    GaN-based light emitting diodes (LEDs) have been fabricated on sapphire substrates with different thicknesses of GaN buffer layer grown by a combination of hydride vapor phase epitaxy and metalorganic chemical vapor deposition. We analyzed the LED efficiency and modulation characteristics with buffer thicknesses of 12 μm and 30 μm. With the buffer thickness increase, cathodoluminescence hyperspectral imaging shows that the dislocation density in the buffer layer decreases from  ∼1.3  ×  108 cm‑2 to  ∼1.0  ×  108 cm‑2, and Raman spectra suggest that the compressive stress in the quantum wells is partly relaxed, which leads to a large blue shift in the peak emission wavelength of the photoluminescence and electroluminescent spectra. The combined effects of the low dislocation density and stress relaxation lead to improvements in the efficiency of LEDs with the 30 μm GaN buffer, but the electrical-to-optical modulation bandwidth is higher for the LEDs with the 12 μm GaN buffer. A rate equation analysis suggests that defect-related nonradiative recombination can help increase the modulation bandwidth but reduce the LED efficiency at low currents, suggesting that a compromise should be made in the choice of defect density.

  4. Deciphering fluid inclusions in high-grade rocks

    Directory of Open Access Journals (Sweden)

    Alfons van den Kerkhof

    2014-09-01

    Full Text Available The study of fluid inclusions in high-grade rocks is especially challenging as the host minerals have been normally subjected to deformation, recrystallization and fluid-rock interaction so that primary inclusions, formed at the peak of metamorphism are rare. The larger part of the fluid inclusions found in metamorphic minerals is typically modified during uplift. These late processes may strongly disguise the characteristics of the “original” peak metamorphic fluid. A detailed microstructural analysis of the host minerals, notably quartz, is therefore indispensable for a proper interpretation of fluid inclusions. Cathodoluminescence (CL techniques combined with trace element analysis of quartz (EPMA, LA-ICPMS have shown to be very helpful in deciphering the rock-fluid evolution. Whereas high-grade metamorphic quartz may have relatively high contents of trace elements like Ti and Al, low-temperature re-equilibrated quartz typically shows reduced trace element concentrations. The resulting microstructures in CL can be basically distinguished in diffusion patterns (along microfractures and grain boundaries, and secondary quartz formed by dissolution-reprecipitation. Most of these textures are formed during retrograde fluid-controlled processes between ca. 220 and 500 °C, i.e. the range of semi-brittle deformation (greenschist-facies and can be correlated with the fluid inclusions. In this way modified and re-trapped fluids can be identified, even when there are no optical features observed under the microscope.

  5. Biotemplating of BaFBr:Eu{sup 2+} for X-ray storage phosphor applications

    Energy Technology Data Exchange (ETDEWEB)

    Kostova, M.H. [Department of Materials Science and Engineering - Glass and Ceramics, University of Erlangen - Nuremberg, Martensstr. 5, D-91058 Erlangen (Germany); Batentschuk, M. [Department of Materials Science and Engineering - Materials for Electronics and Energy Technology, University of Erlangen - Nuremberg, D-91058 Erlangen (Germany); Goetz-Neunhoeffer, F. [GeoZentrum Nordbayern, Mineralogy, University of Erlangen - Nuremberg, D-91058 Erlangen (Germany); Gruber, S. [Department of Materials Science and Engineering - Glass and Ceramics, University of Erlangen - Nuremberg, Martensstr. 5, D-91058 Erlangen (Germany); Winnacker, A. [Department of Materials Science and Engineering - Materials for Electronics and Energy Technology, University of Erlangen - Nuremberg, D-91058 Erlangen (Germany); Greil, P. [Department of Materials Science and Engineering - Glass and Ceramics, University of Erlangen - Nuremberg, Martensstr. 5, D-91058 Erlangen (Germany); Zollfrank, C., E-mail: cordt.zollfrank@ww.uni-erlangen.de [Department of Materials Science and Engineering - Glass and Ceramics, University of Erlangen - Nuremberg, Martensstr. 5, D-91058 Erlangen (Germany)

    2010-09-01

    The design of hierarchically patterned novel structures by replicating the cellular tissue of wood has recently attained increasing interest. X-ray storage phosphor BaFBr:Eu{sup 2+} is manufactured via vacuum assisted repeated infiltration of wood tissue (Pinus sylvestris). A submicrometer precipitate is formed via wet chemical reaction of NH{sub 4}F, BaBr{sub 2}.2H{sub 2}O and EuCl{sub 3}.6H{sub 2}O in methanol. According to scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), the original wood cell walls are filled with the precipitate and completely transformed into BaFBr struts after sintering at 800 deg. C. The optical properties of the biomorphous phosphor microstructure are determined by photoluminescence spectroscopy (PL) at room temperature, photo-stimulated luminescence spectroscopy (PSL) and cathodoluminescence spectroscopy (CL) in the SEM. A broadening of the PSL peak is observed and ascribed to the incorporation of calcium impurities present in the pine wood tissue. The potential of biotemplates for generating highly oriented and optically isolated {mu}m- and sub-{mu}m matrix of X-ray storage phosphor material is illustrated.

  6. A new approach to studying the luminescence spectra of free icosahedral and crystalline argon nanoclusters

    Science.gov (United States)

    Doronin, Yu. S.; Vakula, V. L.; Kamarchuk, G. V.; Tkachenko, A. A.; Samovarov, V. N.

    2016-02-01

    We propose a new approach to analyzing the cathodoluminescence spectra of free argon nanoclusters, forming in a supersonic jet flowing into vacuum. Based on this approach, we conduct an analysis of the intensities of the luminescence bands of neutral and charged excimer complexes (Ar2)* and (Ar+4)*, measured for clusters with an average size ranging from 500 to 8900 atoms per cluster, and a diameter of 32-87 Å. It is shown that the concentration of the substance condensed into clusters, which determines the integrated intensity of the bands, is proportional to the logarithm of the average size of the clusters in the jet. An analysis of the normalized intensities of the (Ar2)* and (Ar+4)* bands for crystalline clusters with an fcc structure allowed us to establish that the luminescence of neutral (Ar2)* molecules comes from within the volume of the cluster, while the charged complexes (Ar+4)* emit from the subsurface layer. We highlighted an area of cluster dimensions at which the jet is dominated by quasi-crystalline clusters with an icosahedral structure, and it is shown that the transition from icosahedral clusters to fcc structures occurs when the average size of the cluster in the jet is N ¯ = (1000-1800) atoms/cluster.

  7. Characterization of CdZnTe after argon ion beam bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Bensalah, H., E-mail: hakima.bensalah@uam.es [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Hortelano, V. [GdS-Optronlab Group, Departamento Fisica Materia Condensada, Universidad de Valladolid, Edificio I-D, Paseo de Belen 1, 47011 Valladolid (Spain); Plaza, J.L. [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, O. [GdS-Optronlab Group, Departamento Fisica Materia Condensada, Universidad de Valladolid, Edificio I-D, Paseo de Belen 1, 47011 Valladolid (Spain); Crocco, J.; Zheng, Q.; Carcelen, V.; Dieguez, E. [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer After argon irradiation using low fluence, the defects on surface were removed. Black-Right-Pointing-Pointer The PL intensity increases after irradiation. This increase should be related to the improved quality of the CdZnTe surfaces. Black-Right-Pointing-Pointer Irradiation process lead to an elimination of Te precipitates from the surfaces of the CdZnTe samples. - Abstract: The objective of this work is to analyze the effects of argon ion irradiation process on the structure and distribution of Te inclusions in Cd{sub 1-x}Zn{sub x}Te crystals. The samples were treated with different ion fluences ranging from 2 to 8 Multiplication-Sign 10{sup 17} cm{sup -2}. The state of the samples before and after irradiation were studied by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Cathodoluminescence, Photoluminescence, and micro-Raman spectroscopy. The effect of the irradiation on the surface of the samples was clearly observed by SEM or AFM. Even for small fluences a removal of polishing scratches on the sample surfaces was observed. Likely correlated to this effect, an important enhancement in the luminescence intensity of the irradiated samples was observed. An aggregation effect of the Te inclusions seems to occur due to the Ar bombardment, which are also eliminated from the surfaces for the highest ion fluences used.

  8. High resolution rare-earth elements analyses of natural apatite and its application in geo-sciences: Combined micro-PIXE, quantitative CL spectroscopy and electron spin resonance analyses

    Energy Technology Data Exchange (ETDEWEB)

    Habermann, D. E-mail: haberman@physik.tu-freiberg.de; Goette, T.; Meijer, J.; Stephan, A.; Richter, D.K.; Niklas, J.R

    2000-03-01

    The rare-earth element (REE) distribution in natural apatite is analysed by micro-PIXE, cathodoluminescence (CL) microscopy and spectroscopy and electron spin resonance (ESR) spectroscopy. The micro-PIXE analyses of an apatite crystal from Cerro de Mercado (Mexico) and the summary of 20 analyses of six francolite (conodonts of Triassic age) samples indicate that most of the REEs are enriched in apatite and francolite comparative to average shale standard (NASC). The analyses of fossil francolite revealing the REE-distribution not to be in balance with the REE-distribution of seawater and fish bone debris. Strong inhomogenous lateral REE-distribution in fossil conodont material is shown by CL-mapping and most probably not being a vital effect. Therefore, the resulting REE-signal from fossil francolite is the sum of vital and post-mortem incorporation. The necessary charge compensation for the substitution of divalent Ca by trivalent REE being done by different kind of electron defects and defect ions.

  9. Use of the Bochum proton microprobe in isotope stratigraphy and paleoceanographic

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, F.; Bruckschen, P.; Korte, C. [Ruhr-University, Bochum (Germany). Institute fuer Geologie; Meijer, J. [Ruhr-Univ., Bochum (Germany). Inst. fuer Physik mit Ionenstrahlen; Veizer, J. [Ruhr-University Bochum (Germany). Institute fuer Geologie]|[Ottawa-Carleton Univ., Ottawa, ON (Canada)

    1998-06-01

    Over the past five years, the proton microprobe at Bochum (Germany) has been used as a trace element tool in the context of isotope stratigraphy and paleoceanographic studies. The Sr, O, and C isotopic composition of some biogenic material (e.g. calcitic brachiopod shells, phosphatic conodonts) is widely accepted to mirror, under favourable conditions, the isotopic composition of the coeval sea water. The latter, in turn, is a function of a variety of global processes, such as climatic change, volcanic activity, plate tectonics or circulation of ocean water. Thus, on the basis of the isotopic properties of fossil shell material, isotope curves can be constructed that reflect variations in the above factors over the entire Phanerozoic. However, as a consequence of the long time elapsed since deposition of the fossils, they are prone to chemical and isotopic alteration and may thus yield equivocal or even irrelevant information if no care is taken to monitor the degree of their diagenetic alteration. Trace element composition of the fossil material, combined with cathodoluminescence investigations, is one of the most frequently utilized tools to assess the diagenetic quality of the samples. Beam current was in the range of a few nA, resulting in charges of 1-10 {mu}C for a single measurement. Detection limits for point analyses were between 10 and 30 ppm for Mn, Fe, Sr, but considerably higher for rare earth elements. Accuracy around 10% for a number of elements analysed is reported. 8 refs., 2 figs.

  10. Reassessing the improbability of a muscular crinoid stem

    Science.gov (United States)

    Gorzelak, Przemysław; Głuchowski, Edward; Salamon, Mariusz A.

    2014-08-01

    Muscular articulations in modern stalked crinoids are only present in the arms. Although it has been suggested that certain coiled-stemmed fossil taxa may have been functionally adapted to utilize muscles, evidence supporting this interpretation is lacking. Here, we use cathodoluminescence and SEM to reveal the skeletal microstructure of the enigmatic coiled-stemmed taxon Ammonicrinus (Flexibilia). Based on the well-established link between skeletal microstructure and the nature of infilling soft tissues in modern echinoderms, we reconstructed the palaeoanatomy of the Middle Devonian ammonicrinids. We show that their median columnals with elongated lateral columnal enclosure extensions (LCEE) have stereom microstructure unexpectedly resembling that in the crinoid muscular arm plates. In particular, large ligamentary facets, that are present on each side of a transverse ridge, are mainly comprised of fine galleried stereom that is indicative of the mutable collagenous tissues. In contrast, fine labyrinthic stereom, commonly associated with muscles, is situated in the periphery on each side of the surface of elongated LCEE. Our findings thus strongly suggest that the muscles may have also been present in the stem of ammonicrinids. These results reassess the previous hypotheses about evolution of muscles in crinoids and provide new insights into the mode of life of Ammonicrinus.

  11. Luminescence behavior and Raman characterization of jade from Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Tuncer Arslanlar, Y. [Physics Department, Faculty of Arts and Sciences, Celal Bayar University, 45140 Muradiye-Manisa (Turkey); Garcia-Guinea, J. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Kibar, R.; Cetin, A.; Ayvacikli, M. [Physics Department, Faculty of Arts and Sciences, Celal Bayar University, 45140 Muradiye-Manisa (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Physics Department, Faculty of Arts and Sciences, Celal Bayar University, 45140 Muradiye-Manisa (Turkey)

    2011-09-15

    Results are presented for the cathodoluminescence (CL), radioluminescence (RL) and thermoluminescence (TL) of jade from Turkey. Jade samples show broad band luminescence from green to red, which, using lifetime-resolved CL, reveals seven overlapping emissions, of which two are dominant. Green emission obtained using spatially resolved CL was associated with Mn{sup 2+} and emission bands centered near at 480 and 530 nm were attributed to {sup 3}P{sub 0}-{sup 3}H{sub 4} and {sup 1}D{sub 2}-{sup 3}H{sub 4} transitions of Pr{sup 3+}, respectively. Different shifts of the peak-wavelengths for 326 and 565 nm were observed with varying jade compositions. The incorporation of the larger K ion causes non-linear variations of the cell dimensions and therefore changes in the Fe---O band distance. We suggest that stress of the jade structure can be linked to the luminescence emission at 326 nm. Raman spectra have also been recorded in order to provide an unequivocal identification of the type of jade. The mechanism for the luminescence of the jade is considered. - Highlights: >Jade spectrum displays numerous broad bands at room and low temperatures. >Different luminescence centers contribute to the overall signal. >The Raman spectra and associated vibrational assignments are reported for jadeite. >The TL sensitivity varies depending on the treatment of the samples.

  12. Lapis lazuli provenance study by means of micro-PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Re, Alessandro, E-mail: alessandro.re@to.infn.it [Dipartimento di Fisica Sperimentale, Universita di Torino, Via Giuria 1, 10125 Torino (Italy); INFN Sezione di Torino and Centre of Excellence ' Nanostructured Interfaces and Surfaces' , Universita di Torino, Via P. Giuria 1, 10125 Torino (Italy); Giudice, Alessandro Lo [Dipartimento di Fisica Sperimentale, Universita di Torino, Via Giuria 1, 10125 Torino (Italy); INFN Sezione di Torino and Centre of Excellence ' Nanostructured Interfaces and Surfaces' , Universita di Torino, Via P. Giuria 1, 10125 Torino (Italy); Angelici, Debora [Dipartimento di Fisica Sperimentale, Universita di Torino, Via Giuria 1, 10125 Torino (Italy); Calusi, Silvia; Giuntini, Lorenzo; Massi, Mirko [Dipartimento di Fisica, Universita and INFN Sezione di Firenze, Via Sansone 1, 50019 Sesto Fiorentino, Firenze (Italy); Pratesi, Giovanni [Dipartimento di Scienze della Terra and Museo di Storia Naturale, Universita di Firenze, Via G. La Pira 4, 50121 Firenze (Italy)

    2011-10-15

    In this paper we report about the micro-PIXE characterisation of lapis lazuli, for a provenance study of this semi-precious stone, used for glyptic as early as 7000 years ago. The final aim is to find markers permitting to identify the origin of the raw material coming from three quarries in regions of historical importance: Afghanistan, Pamir Mountains and Siberia. This may help to reconstruct trade routes, especially for ancient objects for which written testimonies are scanty or absent at all. Due to the heterogeneity of lapis lazuli we concentrate our attention on single phases instead of the whole stone; in particular we focused on two of the main phases: lazurite, responsible for the blue colour, and diopside, the most frequent accessory mineral. This study was preceded and completed by means of microanalysis with Scanning Electron Microscopy (SEM-EDX) and Cold-Cathodoluminescence (cold-CL) analysis. Despite the limited number of analysed samples, results are sufficient to exclude/suggest a few features as provenance markers, partly confirming what has been previously published in literature.

  13. Optical and mechanical properties of nanofibrillated cellulose: Toward a robust platform for next-generation green technologies.

    Science.gov (United States)

    Simão, Claudia D; Reparaz, Juan S; Wagner, Markus R; Graczykowski, Bartlomiej; Kreuzer, Martin; Ruiz-Blanco, Yasser B; García, Yamila; Malho, Jani-Markus; Goñi, Alejandro R; Ahopelto, Jouni; Sotomayor Torres, Clivia M

    2015-08-01

    Nanofibrillated cellulose, a polymer that can be obtained from one of the most abundant biopolymers in nature, is being increasingly explored due to its outstanding properties for packaging and device applications. Still, open challenges in engineering its intrinsic properties remain to address. To elucidate the optical and mechanical stability of nanofibrillated cellulose as a standalone platform, herein we report on three main findings: (i) for the first time an experimental determination of the optical bandgap of nanofibrillated cellulose, important for future modeling purposes, based on the onset of the optical bandgap of the nanofibrillated cellulose film at Eg≈275 nm (4.5 eV), obtained using absorption and cathodoluminescence measurements. In addition, comparing this result with ab-initio calculations of the electronic structure the exciton binding energy is estimated to be Eex≈800 meV; (ii) hydrostatic pressure experiments revealed that nanofibrillated cellulose is structurally stable at least up to 1.2 GPa; and (iii) surface elastic properties with repeatability better than 5% were observed under moisture cycles with changes of the Young modulus as large as 65%. The results obtained show the precise determination of significant properties as elastic properties and interactions that are compared with similar works and, moreover, demonstrate that nanofibrillated cellulose properties can be reversibly controlled, supporting the extended potential of nanofibrillated cellulose as a robust platform for green-technology applications.

  14. Global correlation for strontium isotope curve in the Late Cretaceous of Tibet and dating marine sediments

    Institute of Scientific and Technical Information of China (English)

    HUANG; Sijing; SHI; He; SHEN; Licheng; ZHANG; Meng; WU; Wen

    2005-01-01

    87Sr/86Sr ratios of marine carbonate samples collected from a sedimentary section of the Late Cretaceous in the south of Tibet were measured. Based on the absence of cathodoluminescence and a very low Mn/Sr ratio (average 0.06) of the samples, it is thought that they contain information on the original seawater strontium isotope composition. The strontium isotope evolution curve of the Late Cretaceous in Tibet we established here, is consistent with other coeval curves from Europe, North America and Antarctica, supports the notion that the strontium isotope composition of seawater is governed by global events, which provides a new approach for the inter-continental and inter-basinal correlations of Late Cretaceous in the area and is a complementarity for biostratigraphy. In addition, we attempt to determine the age of the boundaries for Campanian/Santonian and Maastrichtian/Campanian by 87Sr/86Sr ratios for Gamba section in southern Tibet. The two boundaries are located in the thickness of 217 m (83.5 Ma) and 291 m (71.3 Ma), respectively.

  15. Lapis lazuli provenance study by means of micro-PIXE

    Science.gov (United States)

    Re, Alessandro; Giudice, Alessandro Lo; Angelici, Debora; Calusi, Silvia; Giuntini, Lorenzo; Massi, Mirko; Pratesi, Giovanni

    2011-10-01

    In this paper we report about the micro-PIXE characterisation of lapis lazuli, for a provenance study of this semi-precious stone, used for glyptic as early as 7000 years ago. The final aim is to find markers permitting to identify the origin of the raw material coming from three quarries in regions of historical importance: Afghanistan, Pamir Mountains and Siberia. This may help to reconstruct trade routes, especially for ancient objects for which written testimonies are scanty or absent at all. Due to the heterogeneity of lapis lazuli we concentrate our attention on single phases instead of the whole stone; in particular we focused on two of the main phases: lazurite, responsible for the blue colour, and diopside, the most frequent accessory mineral. This study was preceded and completed by means of microanalysis with Scanning Electron Microscopy (SEM-EDX) and Cold-Cathodoluminescence (cold-CL) analysis. Despite the limited number of analysed samples, results are sufficient to exclude/suggest a few features as provenance markers, partly confirming what has been previously published in literature.

  16. In-air broad beam ionoluminescence microscopy as a tool for rocks and stone artworks characterisation.

    Science.gov (United States)

    Lo Giudice, Alessandro; Re, Alessandro; Angelici, Debora; Calusi, Silvia; Gelli, Nicla; Giuntini, Lorenzo; Massi, Mirko; Pratesi, Giovanni

    2012-07-01

    Broad beam ionoluminescence (IL) microscopy is a promising technique for the non-destructive characterisation of rocks and stone objects. Luminescence imaging by means of broad ion beams has been sporadically used by other authors but, to our knowledge, its potential has not yet been fully investigated, neither in geological science nor in other fields. The in-air broad beam IL microscope was developed and installed at the INFN-LABEC external microbeam in Florence. Similar to the cathodoluminescence (CL) microscope, the apparatus exploits a CCD colour camera collecting images (few square millimetres wide, with ~10-μm spatial resolution) of the luminescence emitted by the sample hit by a defocused megaelectron volt (MeV) proton beam. The main differences with the well-established and widespread CL are the possibility of working in air (no sampling or conductive coatings required) and the possibility of combining the analysis with microbeam analysis, such as, for example, μ-IL and μ-PIXE (particle-induced X-ray emission). To show the potential of the technique, IL images of thin sections of lapis lazuli are compared with those obtained by means of an in-vacuum cold CL. An application to the study of stone artworks is also reported. This technique and apparatus will provide a valuable help for interdisciplinary applications, e.g. in geological sciences and in the cultural heritage field.

  17. Origin of modern quartzarenite beach sands in a temperate climate, Florida and Alabama, USA

    Science.gov (United States)

    Mehring, Joseph L.; McBride, Earle F.

    2007-10-01

    Quartzarenite coastal sands extending from eastern Louisiana eastward to Apalachee Bay, Florida, are anomalous: their position 7° north of the Tropic of Cancer contrasts with most other known modern quartzarenites, most of which are in a tropical setting. To determine the origin of these quartzarenite beach sands, we compared the mineralogy of samples taken from Alabama and Florida beaches, rivers that supply sand to the coast, and well cuttings representative of sandstone bedrock exposed in the Alabama coastal plain. To help assess the abundance of recycled quartz, and accepting the conventional wisdom that rounded sand-size quartz grains are recycled, we quantified the roundness of quartz grains in thin sections of river, beach, and well samples. We also determined the abundance of recycled grains with authigenic quartz using cathodoluminescence. River sands on Precambrian and Paleozoic bedrock in the study area have subarkose and sublitharenite compositions. However, as far as 200 km inland from the coast, river sands have attained quartzarenite composition and all rivers are presently delivering sand with at least 97% quartz to the coast. Rivers develop quartzarenite sand composition where they traverse poorly consolidated Tertiary sandstones, all of which we sampled are composed of > 95% quartz. Published experimental work indicates that abrasional rounding of sand-size quartz by rivers is insignificant and rounding in beaches is extremely slow. Hence, the abundance of quartz grains with some degree of rounding (96% for beaches; > 75% for rivers) further attests to the abundance of recycled quartz.

  18. Fluid inclusions hidden in coesite-bearing zircons in ultrahigh-pressure metamorphic rocks from southwestern Sulu terrane in eastern China

    Institute of Scientific and Technical Information of China (English)

    LIU Fulai; XU Zhiqin

    2004-01-01

    Primary fluid inclusions, together with coesite mineral inclusions, are identified in the same zircon domains by laser Raman spectroscopy, cathodoluminescence (CL) image and micro-texture analysis in paragneiss and eclogite from the main drilling hole of Chinese Continental Scientific Drilling Project in southwestern Sulu terrane. Most fluid inclusions are characterized by CO2 (gas)-H2O (liquid) two-phase, a few by H2O one-phase liquid inclusions. These features indicate that the eclogite and its country-rocks may be located in the "wet system" rather than in the "dry system" during UHP metamorphism. SHRIMP U-Pb dating indicates that the timing of trapping the fluid and coesite inclusions in metamorphic zircon domains is about 233.7 ± 4.3 Ma, which may represent the age of zircon growth in the stage of pressure decrease but temperature increase during the retrograde period of UHP metamorphism thus indicating the fluid activity still under the UHP conditions. The zircons further overgrew at about 213.2 ± 5.2 Ma in response to amphibolite-facies retrogression. Therefore, fluid activity in the Sulu UHP metamorphic rocks principally occurred during the exhumation of UHP slab in the Middle to Late Triassic. The present results not only provide insight into the fluid property and fluid-rock interaction mechanism in the Sulu-Dabie UHP terrane, but also present a new means to exactly identify the primary fluid inclusions preserved in zircons from the UHP metamorphic rocks.

  19. Synthesis and Electrical Prop erties of TiO2 Nanoparticles Emb edded in Polyamide-6 Nanofib ers Via Electrospinning

    Institute of Scientific and Technical Information of China (English)

    R Nirmala; Jin Won Jeong; R Navamathavan; Hak Yong Kim

    2011-01-01

    We report on the synthesis and characterizations of TiO2 nanoparticles embedded in polyamide-6 composite nanofibers by using electrospinning technique. The influence of substrate on the electrical charac-teristics of polyamide-6/TiO2 composite nanofibers was investigated. The resultant nanofibers exhibit good incorporation of TiO2 nanoparticles. The doping of TiO2 nanoparticles into the polyamide-6 nanofibers were confirmed by high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Pho-toluminescence (PL) and cathodoluminescence (CL) spectroscopy were also used to characterize the samples. The PL and CL spectra reveal that the as-spun polyamide-6/TiO2 composite nanofibers consisted of overlapping of two broad emission bands due to the contribution of polyamide-6 (centered at about 475 nm), which might originate from organic functional groups of polyamide-6 and TiO2 nanoparticles (centered around 550 nm). The electrical conductivity of the polyamide-6/TiO2 composite nanofibers on different substrates was carried out. It was found that the electrical conductivity of the polyamide-6/TiO2 composite nanofibers on silicon substrate was in the range of 1∼3 µA, and about 1 to 20 pA for the paper and glass substrates.

  20. Transformation of c-oriented nanowall network to a flat morphology in GaN films on c-plane sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Kesaria, Manoj; Shetty, Satish [International Centre for Material Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Cohen, P.I. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 (United States); Shivaprasad, S.M., E-mail: smsprasad@jncasr.ac.in [International Centre for Material Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2011-11-15

    Highlights: {yields} High quality wurtzite structures GaN nanowall network formed on c-plane sapphire. {yields} Tapering of nanowalls at the apex cause electron confinement effects. {yields} Temperature dependent transformation of the six fold nanowall network to a flat morphology. {yields} Growth kinetics is influenced by adatom diffusion, interactions and bonding for GaN layer. -- Abstract: The work significantly optimizes growth parameters for nanostructured and flat GaN film in the 480-830 {sup o}C temperature range. The growth of ordered, high quality GaN nanowall hexagonal honeycomb like network on c-plane sapphire under nitrogen rich (N/Ga ratio of 100) conditions at temperatures below 700 {sup o}C is demonstrated. The walls are c-oriented wurtzite structures 200 nm wide at base and taper to 10 nm at apex, manifesting electron confinement effects to tune optoelectronic properties. For substrate temperatures above 700 {sup o}C the nanowalls thicken to a flat morphology with a dislocation density of 10{sup 10}/cm{sup 2}. The role of misfit dislocations in the GaN overlayer evolution is discussed in terms of growth kinetics being influenced by adatom diffusion, interactions and bonding at different temperatures. The GaN films are characterized by reflection high energy electron diffraction (RHEED), field emission scanning electron (FESEM), high resolution X-ray diffraction (HRXRD) and cathodoluminescence (CL).

  1. A modification of Eu incorporation sites by the dissociation of hydrogen defect complexes in Mg co-doped Eu doped gallium nitride

    Science.gov (United States)

    Mitchell, Brandon; Poplawsky, Jonathan; Dierolf, Volkmar

    2013-03-01

    Europium doped gallium nitride (Eu:GaN) is a promising candidate as a material for red LEDs that can monolithically be integrated with existing nitride based lighting technology. Photoluminescence (PL) and cathodoluminescence (CL) studies have revealed, however, that the majority incorporation environment (site) for the Eu is not efficiently excited by electron hole pairs. To improve this efficiency, Mg was co-doped into Eu:GaN during metal organic chemical vapor deposition and multiple new incorporation environments were discovered. These new sites show a high efficiency at room temperature and have been attributed to the coupling of a Mg-H complex to the majority Eu site. However, we also observe that sustained electron beam irradiation produced a semi-permanent change in the CL spectra of the sample. It was demonstrated that this change occurs in two distinct steps which exhibit a pronounced temperature dependence. Our observations point toward a dynamic system in which the Mg-H bond is broken and the hydrogen moves within the epi-layer. Details of this behavior will be discussed.

  2. Fabrication and applications of orientation-patterned gallium arsenide for mid-infrared generation

    Energy Technology Data Exchange (ETDEWEB)

    Grisard, A.; Gutty, F.; Lallier, E. [Thales Research and Technology France, 1 av. Augustin Fresnel, 91767 Palaiseau Cedex (France); Gerard, B. [III-V Lab, 1 av. Augustin Fresnel, 91767 Palaiseau Cedex (France); Jimenez, J. [GdS Optronlab, Fisica Materia Condensada, Universidad de Valladolid, 47011 Valladolid (Spain)

    2012-07-15

    Nonlinear optical materials play a key role in the development of coherent sources of radiation, by frequency conversion of light from other light sources, e.g. diode, solid-state, and fiber lasers, into spectral ranges where few lasers exist or perform poorly. Based on the principle of the quasi-phase matching, the design and fabrication of orientation-patterned Gallium Arsenide crystals (OP-GaAs) has recently led to demonstrations of second harmonic generation, optical parametric generation, amplification and oscillation from 1 to 12 {mu}m. The most efficient fabrication route for these crystals relies on the use of the near-equilibrium growth process HVPE (Hydride Vapour Phase Epitaxy), by orientation-selective regrowth on OP-GaAs template wafers with a thickness suited to bulk nonlinear optics. This work deals with recent characterizations based on optical experiments and cathodoluminescence measurements, targeting the identification of the main defects, their spatial distribution, and their relation to the optical propagation losses. Latest improvements of the HVPE growth step have enabled to reach an unprecedented level of losses, below 0.016 cm{sup -1}, and a large range of available QPM periods and thickness of structures (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Structural and optical nanoscale analysis of GaN core-shell microrod arrays fabricated by combined top-down and bottom-up process on Si(111)

    Science.gov (United States)

    Müller, Marcus; Schmidt, Gordon; Metzner, Sebastian; Veit, Peter; Bertram, Frank; Krylyuk, Sergiy; Debnath, Ratan; Ha, Jong-Yoon; Wen, Baomei; Blanchard, Paul; Motayed, Abhishek; King, Matthew R.; Davydov, Albert V.; Christen, Jürgen

    2016-05-01

    Large arrays of GaN core-shell microrods were fabricated on Si(111) substrates applying a combined bottom-up and top-down approach which includes inductively coupled plasma (ICP) etching of patterned GaN films grown by metal-organic vapor phase epitaxy (MOVPE) and selective overgrowth of obtained GaN/Si pillars using hydride vapor phase epitaxy (HVPE). The structural and optical properties of individual core-shell microrods have been studied with a nanometer scale spatial resolution using low-temperature cathodoluminescence spectroscopy (CL) directly performed in a scanning electron microscope (SEM) and in a scanning transmission electron microscope (STEM). SEM, TEM, and CL measurements reveal the formation of distinct growth domains during the HVPE overgrowth. A high free-carrier concentration observed in the non-polar \\{ 1\\bar{1}00\\} HVPE shells is assigned to in-diffusion of silicon atoms from the substrate. In contrast, the HVPE shells directly grown on top of the c-plane of the GaN pillars reveal a lower free-carrier concentration.

  4. Novel, low-cost solid-liquid-solid process for the synthesis of α-Si3N4 nanowires at lower temperatures and their luminescence properties.

    Science.gov (United States)

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Fang, Minghao; Liu, Yan-gai; Wu, Xiaowen; Hu, Xiaozhi; Zhang, Shaowei

    2015-11-26

    Ultra-long, single crystal, α-Si3N4 nanowires sheathed with amorphous silicon oxide were synthesised by an improved, simplified solid-liquid-solid (SLS) method at 1150 °C without using flowing gases (N2, CH4, Ar, NH3, etc.). Phases, chemical composition, and structural characterisation using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM/HRTEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) showed that the nanowires had Si3N4@SiOx core-shell structures. The growth of the nanowires was governed by the solid-liquid-solid (SLS) mechanism. The room temperature photoluminescence (PL) and cathodoluminescence (CL) spectra showed that the optical properties of the α-Si3N4 nanowires can be changed along with the excitation wavelength or the excitation light source. This work can be useful, not only for simplifying the design and synthesis of Si-related nanostructures, but also for developing new generation nanodevices with changeable photoelectronic properties.

  5. Ultraviolet and visible range plasmonics of a topological insulator

    CERN Document Server

    Ou, Jun-Yu; Adamo, Giorgio; Sulaev, Azat; Wang, Lan; Zheludev, Nikolay I

    2014-01-01

    The development of metamaterials, data processing circuits and sensors for the visible and UV parts of the spectrum is hampered by the lack of low-loss media supporting plasmonic excitations and drives the intense search for plasmonic materials beyond noble metals. By studying plasmonic nanostructures fabricated on the surface of topological insulator $\\mbox{Bi}_{1.5}\\mbox{Sb}_{0.5}\\mbox{Te}_{1.8}\\mbox{Se}_{1.2}$ we found that it is orders of magnitude better plasmonic material than gold and silver in the blue-UV range. Metamaterial fabricated from $\\mbox{Bi}_{1.5}\\mbox{Sb}_{0.5}\\mbox{Te}_{1.8}\\mbox{Se}_{1.2}$ show plasmonic resonances from 350 nm to 550 nm while surface gratings exhibit cathodoluminescent peaks from 230 nm to 1050 nm. The negative permittivity underpinning plasmonic response is attributed to the combination of bulk interband transitions and surface contribution of the topologically protected states. The importance of our result is in the identification of new mechanisms of negative permittiv...

  6. Crystal field analysis of Pm$^{3+}$ (4$^{f4}) and Sm$^{3+}$ (4$^{f5}) and lattice location studies of $^{147}$Nd and $^{147}$Pm in w-AlN

    CERN Document Server

    Vetter, Ulrich; Nijjar, Anmol S; Zandi, Bahram; Öhl, Gregor; Wahl, Ulrich; De Vries, Bart; Hofsäss, Hans; Dietrich, Marc

    2006-01-01

    We report a detailed crystal field analysis of Pm3+ and Sm3+ as well as lattice location studies of 147Pm and 147Nd in 2H-aluminum nitride (w-AlN). The isotopes of mass 147 were produced by nuclear fission and implanted at an energy of 60 keV. The decay chain of interest in this work is 147Nd→147Pm→147Sm (stable). Lattice location studies applying the emission channeling technique were carried out using the β− particles and conversion electrons emitted in the radioactive decay of 147Nd→147Pm. The samples were investigated as implanted, and also they were investigated after annealing to temperatures of 873 K as well as 1373 K. The main fraction of about 60% of both 147Pm as well as 147Nd atoms was located on substitutional Al sites in the AlN lattice; the remainder of the ions were located randomly within the AlN lattice. Following radioactive decay of 147Nd, the cathodoluminescence spectra of Pm3+ and Sm3+ were obtained between 500 nm and 1050 nm at sample temperatures between 12 K and 300 K. High-re...

  7. Distribution and characteristics of diamonds from Myanmar

    Science.gov (United States)

    Win, T. T.; Davies, R. M.; Griffin, W. L.; Wathanakul, P.; French, D. H.

    2001-08-01

    Diamonds occur in headless placers at several locations within Myanmar. Twenty-six stones from the Momeik area of northern Myanmar and 111 stones from the Theindaw area of southern Myanmar have been studied to characterise their morphology, crystal forms, colour, degree of resorption, surface features, internal structures, mineral inclusions, and nitrogen content and aggregation state. Most stones grew originally as octahedra, but now show very high degrees of resorption, and highly polished surfaces, reflecting transport in a magma. Etch features are abundant, and breakage and abrasion are common, due to alluvial transport. Brown radiation spots are common, suggesting that these diamonds have a long history in surface environments. Cathodoluminescence (CL) images of plates and whole stones commonly display marked oscillatory zoning of yellow and blue bands, outlining octahedral growth zones. Many other stones show uniform yellow CL. Syngenetic mineral inclusions identified thus far are mainly of peridotitic paragenesis and include olivine, chromite and native iron. Infrared spectroscopy studies show that ˜10% of the diamonds have very low-N contents (Type II diamonds). More N-rich diamonds show high degrees of aggregation (Type IaAB). Both types are consistent with derivation from the upper mantle, rather than from crustal metamorphic sources. The primary source of these diamonds is believed to be an alkaline igneous rock (lamproitic rather than kimberlitic) but they may have reached their present locations via a secondary collector such as a sedimentary rock.

  8. Effect of high temperature annealing on defects and optical properties of ZnO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, M.; Wang, D.D.; Zou, B.; Chen, Z.Q. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Kawasuso, A. [Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Sekiguchi, T. [Advanced Electronic Materials Center, National Institute for Materials Science, Tsukuba 305-0044 (Japan)

    2012-11-15

    Hydrothermal grown ZnO single crystals were annealed in N{sub 2} or O{sub 2} between 900 and 1300 C. Positron lifetime measurements reveal a single lifetime in all the ZnO samples before and after annealing. The positron lifetime is about 181 ps after annealing at 900 C in either N{sub 2} or O{sub 2} atmosphere. However, increase of the positron lifetime is observed after further annealing the sample at higher temperatures up to 1300 C, and it has a faster increase in O{sub 2} ambient. Temperature dependence measurements show that the positron lifetime has very slight increase with temperature for the 900 C annealed sample, while it shows notable variation for the sample annealed at 1300 C. This implied that annealing at high temperature introduces additional defects. These defects are supposed to be Zn vacancy-related defects. Cathodoluminescence (CL) measurements indicates enhancement of both UV and green emission after annealing, and the enhancement of green emission is much stronger for the samples annealed in O{sub 2} ambient. The possible origin of green emission is tentatively discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Provenance records of the North Jiangsu Basin,East China:Zircon U-Pb geochronology and geochemistry from the Paleogene Dainan Formation in the Gaoyou Sag

    Institute of Scientific and Technical Information of China (English)

    Chun-Ming; Lin; Xia; Zhang; Ni; Zhang; Shun-Yong; Chen; Jian; Zhou; Yu-Rui; Liu

    2014-01-01

    Detailed zircon U-Pb dating and whole-rock geochemical analyses were carried out on the sedimentary rocks of the Paleogene Dainan Formation from Gaoyou Sag in the North Jiangsu Basin,East China.Whole-rock rare earth element characteristics suggest that the provenance was mainly from the Late Proterozoic low-grade metamorphic felsic rocks in the Dabie-Sulu orogenic belt,with the parent rocks probably being the I-type high-potassium granite gneiss.Cathodoluminescence images indicate that most of the detrital zircons are originally magmatic.A few zircons show overgrowths,indicating multiple-episode tectonic events.The U-Pb age distribution patterns of the detrital zircons suggest four main magmatic episodes in the provenance:Late Archean-Early Proterozoic(2450-2600 Ma),Early Proterozoic(1700-1900 Ma),Late Proterozoic(700-850 Ma),and Late Paleozoic-Mesozoic(100-300 Ma).These zircon U-Pb age and whole-rock geochemical results suggest that the sediments of the Dainan Formation were mainly sourced from the recycled orogenic belts within and/or around the North Jiangsu Basin,including the basement of the Yangtze Block,the Neoproterozoic rocks in the Dabie-Sulu orogenic belt,and the Mesozoic igneous rocks in the south part of Zhangbaling Uplift.

  10. Determination of the Optimal Shell Thickness for Self-Catalyzed GaAs/AlGaAs Core-Shell Nanowires on Silicon.

    Science.gov (United States)

    Songmuang, R; Giang, Le Thuy Thanh; Bleuse, J; Den Hertog, M; Niquet, Y M; Dang, Le Si; Mariette, H

    2016-06-08

    We present a set of experimental results showing a combination of various effects, that is, surface recombination velocity, surface charge traps, strain, and structural defects, that govern the carrier dynamics of self-catalyzed GaAs/AlGaAs core-shell nanowires (NWs) grown on a Si(111) substrate by molecular beam epitaxy. Time-resolved photoluminescence of NW ensemble and spatially resolved cathodoluminescence of single NWs reveal that emission intensity, decay time, and carrier diffusion length of the GaAs NW core strongly depend on the AlGaAs shell thickness but in a nonmonotonic fashion. Although 7 nm AlGaAs shell can efficiently suppress the surface recombination velocity of the GaAs NW core, the influence of the surface charge traps and the strain between the core and the shell that redshift the luminescence of the GaAs NW core remain observable in the whole range of the shell thickness. In addition, the band bending effect induced by the surface charge traps can alter the scattering of the excess carriers inside the GaAs NW core at the core/shell interface. If the AlGaAs shell thickness is larger than 50 nm, the luminescence efficiency of the GaAs NW cores deteriorates, ascribed to defect formation inside the AlGaAs shell evidenced by transmission electron microscopy.

  11. Ordered arrays of InGaN/GaN dot-in-a-wire nanostructures as single photon emitters

    Science.gov (United States)

    Lazić, Snežana; Chernysheva, Ekaterina; Gačević, Žarko; García-Lepetit, Noemi; van der Meulen, Herko P.; Müller, Marcus; Bertram, Frank; Veit, Peter; Christen, Jürgen; Torres-Pardo, Almudena; González Calbet, José M.; Calleja, Enrique; Calleja, José M.

    2015-03-01

    The realization of reliable single photon emitters operating at high temperature and located at predetermined positions still presents a major challenge for the development of solid-state systems for quantum light applications. We demonstrate single-photon emission from two-dimensional ordered arrays of GaN nanowires containing InGaN nanodisks. The structures were fabricated by molecular beam epitaxy on (0001) GaN-on-sapphire templates patterned with nanohole masks prepared by colloidal lithography. Low-temperature cathodoluminescence measurements reveal the spatial distribution of light emitted from a single nanowire heterostructure. The emission originating from the topmost part of the InGaN regions covers the blue-to-green spectral range and shows intense and narrow quantum dot-like photoluminescence lines. These lines exhibit an average linear polarization ratio of 92%. Photon correlation measurements show photon antibunching with a g(2)(0) values well below the 0.5 threshold for single photon emission. The antibunching rate increases linearly with the optical excitation power, extrapolating to the exciton decay rate of ~1 ns-1 at vanishing pump power. This value is comparable with the exciton lifetime measured by time-resolved photoluminescence. Fast and efficient single photon emitters with controlled spatial position and strong linear polarization are an important step towards high-speed on-chip quantum information management.

  12. GaN/AlGaN nanocavities with AlN/GaN Bragg reflectors grown in AlGaN nanocolumns by plasma assisted MBE

    Energy Technology Data Exchange (ETDEWEB)

    Ristic, J.; Calleja, E.; Fernandez-Garrido, S. [ISOM and Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s n, 28040 Madrid (Spain); Trampert, A.; Jahn, U.; Ploog, K.H. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Povoloskyi, M.; Carlo, A. Di [Dept. di Ingegneria Elettronica, Universita di Roma ' ' Tor Vegata' ' , 00133 Roma (Italy)

    2005-02-01

    The successful growth of AlGaN nanocolumns by plasma assisted MBE, with different Al compositions, opened the way for achieving nano-heterostructures including GaN Quantum Discs (QDss). The luminescence emission from the QDss embedded in the AlGaN nanocolumns was tuned by changing their thickness and/or the Al composition of the barriers. Such a nano-heterostructure was then enclosed between two AlN/GaN Distributed Bragg Reflectors (DBR), with nominal reflectivities of 90 and 50%. The choice of the AlN/GaN bilayers for the DBRs allowed to reach these reflectivity values with a significantly lower number of periods, as compared to the AlGaN/GaN stacks. The resulting nanocavity has been characterized by cathodoluminescence (CL), and Scanning and Transmission Electron Microscopy (SEM, TEM). CL measurements show that the emission from the nanocavity is quite close to the targeted value. TEM data points to the need of optimized conditions to grow AlN columnar layers in order to avoid the lateral overgrowth in the columnar nanostructure. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Blue-to-green single photons from InGaN/GaN dot-in-a-nanowire ordered arrays

    Science.gov (United States)

    Chernysheva, E.; Gačević, Ž.; García-Lepetit, N.; van der Meulen, H. P.; Müller, M.; Bertram, F.; Veit, P.; Torres-Pardo, A.; González Calbet, J. M.; Christen, J.; Calleja, E.; Calleja, J. M.; Lazić, S.

    2015-07-01

    Single-photon emitters (SPEs) are at the basis of many applications for quantum information management. Semiconductor-based SPEs are best suited for practical implementations because of high design flexibility, scalability and integration potential in practical devices. Single-photon emission from ordered arrays of InGaN nano-disks embedded in GaN nanowires is reported. Intense and narrow optical emission lines from quantum dot-like recombination centers are observed in the blue-green spectral range. Characterization by electron microscopy, cathodoluminescence and micro-photoluminescence indicate that single photons are emitted from regions of high In concentration in the nano-disks due to alloy composition fluctuations. Single-photon emission is determined by photon correlation measurements showing deep anti-bunching minima in the second-order correlation function. The present results are a promising step towards the realization of on-site/on-demand single-photon sources in the blue-green spectral range operating in the GHz frequency range at high temperatures.

  14. Grassy Silica Nanoribbons and Strong Blue Luminescence

    Science.gov (United States)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-01-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications. PMID:27666663

  15. Cadmium hydroxide and oxide nanoporous walls with high performance photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Cheng, E-mail: ychang0127@gmail.com

    2015-07-15

    Highlights: • Cd(OH){sub 2} nanowalls were directly grown on glass substrate by hydrothermal method. • The thicknesses of Cd(OH){sub 2} nanowalls can be effectively controlled by HMTA. • Cd(OH){sub 2} and CdO nanoporous walls exhibit very strong and broad emission properties. • Cd(OH){sub 2} and CdO nanoporous walls have exhibited very effective photocatalysts. • The two mixture nanoporous walls are beneficial for optoelectronic applications. - Abstract: Cadmium hydroxide nanowalls were directly grown on glass substrate by a hydrothermal method. The concentration of hexamethylenetetramine plays a crucial role for controlling the thicknesses of cadmium hydroxide nanowalls. A part of the cadmium hydroxide nanowalls can be converted to cadmium oxide nanoporous walls by annealing cadmium hydroxide in air at 350 °C for 1 h. Cadmium hydroxide and oxide nanoporous walls exhibited very strong and broad emission properties in the cathodoluminescence spectrum. Furthermore, cadmium hydroxide and oxide nanoporous walls can also provide a higher surface-to-volume ratio to result their higher photocatalytic performance in degradation of methylene blue.

  16. Deep green emission at 570nm from InGaN/GaN MQW active region grown on bulk AlN substrate

    Science.gov (United States)

    Shahedipour-Sandvik, F.; Grandusky, J. R.; Jamil, M.; Jindal, V.; Schujman, S. B.; Schowalter, L. J.; Liu, R.; Ponce, F. A.; Cheung, M.; Cartwright, A.

    2005-09-01

    Relatively intense deep-green/yellow photoluminescence emission at ~600 nm is observed for InGaN/GaN multi quantum well (MQW) structures grown on bulk AlN substrates, demonstrating the potential to extend commercial III-Nitride LED technology to longer wavelengths. Optical spectroscopy has been performed on InGaN MQWs with an estimated In concentration of greater than 50% grown by metalorganic chemical vapor phase epitaxy at 750oC. Temperature- and power-dependence, time-resolved photoluminescence as well as spatially resolved cathodoluminescence measurements and transmission electron microscopy have been applied to understand and elucidate the nature of the mechanism responsible for radiative recombination at 600nm as well as higher energy emission band observed in the samples. A comparison between samples grown on bulk AlN and sapphire substrates indicate a lower degree of compositional and/or thickness fluctuation in the latter case. Our results indicate the presence of alloy compositional fluctuation in the active region despite the lower strain expected in the structure contrary to that of low In composition active regions deposited on bulk GaN substrates. Transient photoluminescence measurements signify a stretched exponential followed by a power decay to best fit the luminescence decay indicative of carrier hopping in the active region. Our results point to the fact that at such high In composition (>30%) InGaN compositional fluctuation is still a dominant effect despite lower strain at the substrate-epi interface.

  17. Whispering Gallery Modes in Hexagonal Zinc Oxide Micro- and Nanocrystals

    Science.gov (United States)

    Nobis, Thomas; Kaidashev, Evgeni M.; Rahm, Andreas; Lorenz, Michael; Grundmann, Marius

    The resonator properties of zinc oxide (ZnO) micro- and nanocrystals grown by a novel high pressure pulsed laser deposition process have been investigated at room temperature by cathodoluminescence (CL), spatially resolved CL-imaging and polarization resolved micro-photoluminescence (μ-PL) within the visible spectral range. The spectra exhibit a series of comparatively sharp and almost equidistant resonance lines. Using a simple plane wave interference model and taking into account the spectral characteristic n(ω) of the refractive index of ZnO, we can unambiguously attribute those lines to whispering gallery modes (WGMs) of a two dimensional hexagonal resonator. The predicted resonator diameters agree well with the measured crystal sizes. Tapered, high aspect ratio ZnO nanoneedles furthermore allow systematic investigations of the WGMs as a function of cavity diameter D down to zero. Hence, the transition from a multi-mode to a single mode cavity is directly observed. μ-PL experiments demonstrate that the WGMs are mainly TM polarized.

  18. Effect of inter-layer strain interaction on the optical properties of Ge/Si(001) island multi-layers

    Institute of Scientific and Technical Information of China (English)

    M. De Seta; G. Capellini; F. Evangelieti; C. Ferrari; L. Lazzarini; G. Salviati; R. W. Peng; S. S.Jiang

    2007-01-01

    In this paper we present a study on the influence of the number and the thickness of silicon spacer layer on the optical properties of single- and multi-layers of self assembled Ge/Si (001) islands performed by means of cathodoluminescence spectroscopy, high resolution X-ray diffraction and transmission electron microscopy. In single-layer sample, we do not evidence dependence of the island no-phonon emission peak position on the silicon cap-layer thickness. In multi-layer samples having a thin (33 nm) silicon spacer layer the no-phonon emission energyvalue progressively blue-shifts for an increasing number of island layers. This is interpreted as an enhanced intermixing driven by the strain interaction existing between island layers. On the contrary, island emission energy position is independent on the number of layers in the sample series having a thicker spacer layer (60 nm). These findings are consistent with the X-ray diffraction observation that islands belonging to different layers have the same composition. As a consequence we can conclude that multilayers with 60-nm spaced islands layer are more homogeneous and ordered.

  19. Genetic mechanism and prediction of Paleozoic clastic eureservoirs in platform of Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the pore cast and cathodolumines-cence thin sections, diagenesis process, source rock matura-tion history, structural evolution and reservoir quality characteristics, the points of view that the porosities of Pa-leozoic clastic eureservoirs in the platform of the Tarim Ba-sin are mainly secondary, and the dissolution plays an unignorable role in the formation of eureservoirs, are put forward. In this paper, a series of criteria for the recognition of the secondary porosities, the occurrence extent and classi-fication of secondary porosity are introduced, and three kinds of dissolution mechanism--the aluminosilicate dis-solution, the silicon dioxide dissolution and the carbonate dissolution--to generate the secondary porosity are come up with. The formation, distribution, preservation and dis-appearance of eureservoirs are controlled by the paleo- structural framework and evolution, and hydrocarbon filling and discharging. Paleostructural framework manipulate the migration path and direction of the acid fluid so as to deter-mine the position and extent of the dissolution. Paleostruc-ture highs and continuous paleouplifts are in favor of devel-oping the secondary porosity. The hydrocarbon filling made the secondary porosities preserved and the hydrocarbon discharging let the secondary porosities filled by later calcite or quartz overgrowth cements. Paleostructure highs and continuous paleouplifts during the maturation period of Cambrian, Ordovician and Carboniferous source rocks (corresponding to S, P and K) are main areas for eureservoirs developing.

  20. Transport, Growth Mechanisms, and Material Quality in GaN Epitaxial Lateral Overgrowth

    Energy Technology Data Exchange (ETDEWEB)

    Baca, Albert G.; Bartram, M.E.; Coltrin, M.E.; Crawford, M.H.; Han, J.; Missert, N.; Willan, C.C.

    1999-01-11

    Growth kinetics, mechanisms, and material quality in GaN epitaxial lateral over-growth (ELO) were examined using a single mask of systematically varied patterns. A 2-D gas phase reaction/diffusion model describes how transport of the Ga precursor to the growth surface enhances the lateral rate in the early stages of growth. In agreement with SEM studies of truncated growth runs, the model also predicts the dramatic decrease in the lateral rate that occurs as GaN over-growth reduces the exposed area of the mask. At the point of convergence, a step-flow coalescence mechanism is observed to fill in the area between lateral growth-fronts. This alternative growth mode in which a secondary growth of GaN is nucleated along a single convergence line, may be responsible for producing smooth films observed to have uniform cathodoluminescence (CL) when using 1{micro}m nucleation zones. Although emission is comprised of both UV ({approximately}365nm) and yellow ({approximately}550nm) components, the spectra suggest these films have reduced concentrations of threading dislocations normally associated with non-radiative recombination centers and defects known to accompany growth-front convergence lines.

  1. Radiation-induced defects, energy storage and release in nitrogen solids

    Science.gov (United States)

    Savchenko, E.; Khyzhniy, I.; Uyutnov, S.; Bludov, M.; Barabashov, A.; Gumenchuk, G.; Bondybey, V.

    2017-02-01

    New trends in the study of radiation effects in nitrogen solids with a focus on the defect-induced processes are presented. An electron beam of subthreshold energy was used to generate radiation defects via electronic subsystem. Experimental techniques developed enabled us to detect neutral and charged defects of both signs. Defect production and desorption were monitored using optical and current emission spectroscopy: cathodoluminescence CL, thermally stimulated luminescence TSL and exoelectron emission TSEE along with the detection of postdesorption. Our results show stabilization and accumulation of radiation defects – ionic centres of both signs (N4 +, N3 +, N3 -), trapped electrons and radicals (N, N3). The neutralization reactions: N4 ++e-→N4 *→N2 *(a‘1Σu -)+N2 *(a‘1Σu -) +ΔE 1 →N2 +N2 +2hν+ΔE 2 and N3 ++e-→N*(2D)+N2(1Σg +)+ΔE 3→N(4S)+N2(1Σg +)+h γ+ΔE 3 are shown to be the basis of defect production and anomalous low-temperature post-desorption ALTpD. The part played by pre-existing and radiation-induced defects in energy storage is discussed.

  2. Thallium and manganese complexes involved in the luminescence emission of potassium-bearing aluminosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Gonzalez, Miguel A., E-mail: miguel.gomez@mncn.csic.es [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid E-28006 (Spain); Garcia-Guinea, Javier, E-mail: guinea@mncn.csic.es [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid E-28006 (Spain); Garrido, Fernando, E-mail: fernando.garrido@mncn.csic.es [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid E-28006 (Spain); Townsend, Peter D., E-mail: pdtownsend@gmail.com [School of Science and Technology, University of Sussex, Brighton BN1 9QH (United Kingdom); Marco, Jose-Francisco, E-mail: jfmarco@iqfr.csic.es [Instituto de Química-Física Rocasolano, CSIC, Calle Serrano 119, Madrid E-28006 (Spain)

    2015-03-15

    The luminescence emission at 285 nm in natural K-feldspar has been studied by Russian groups and associated with thallium ions in structural positions of K{sup +} sites as artificially thallium-doped feldspars display the same emission band. Here attention is focussed on spectra of CL emission bands centered near 285 and 560 nm from paragenetic adularia, moscovite and quartz micro-inclusions. With accesorial thallium they show clear resemblances to each other. Associated sedimentary and hydrothermal aluminosilicate samples collected from Guadalix (Madrid, Spain) were analyzed with a wide range of experimental techniques including Environmental Scanning Electron Microscopy (ESEM) with an attached X-Ray Energy-Dispersive Spectrometer (EDS) and a cathodoluminescence probe (CL) and Electron Probe Microanalysis (EPMA), X-Ray Fluorescence Spectrometry (XRF), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), Differential and Thermogravimetric Analyses (DTA-TG), radioluminescence (RL), Mössbauer spectroscopy and X-Ray Photoelectron Spectrometry (XPS). The luminescence emission bands at 285 and 560 nm seem to be associated with hydrous thallium–manganese complexes bonded to potassium-bearing aluminosilicates since various minerals such as K-feldspar, moscovite and quartz micro-inclusions display similar CL spectra, accesorial thallium and hydroxyl groups. The presence of iron introduces a brown color which is attributed to submicroscopic iron oxides detectable in the optical and chemical microanalysis, but this does not contribute to the luminescence emission. The XPS Mn 2p spectrum of the adularia sample at room temperature is composed of a spin–orbit doublet plus clear shake-up satellite structure ∼4 eV above the main photoemision lines and is consistent with Mn{sup 2+} in good agreement with the observed luminescence emission at 560 nm for aluminosilicates produced by a {sup 4}T1({sup 4}G)→{sup 6}A1({sup 6}S) transition in tetrahedrally

  3. Forms of uranium associated to silica in the environment of the Nopal deposit (Mexico)

    Science.gov (United States)

    Allard, T.; Othmane, G.; Menguy, N.; Vercouter, T.; Morin, G.; Calas, G.; Fayek, M.

    2011-12-01

    The understanding of the processes that control the transfers of uranium in the environment is necessary for the safety assessement of nuclear waste repositories. In particular, several poorly ordered phases (e.g. Fe oxihydroxides) are expected to play an important role in trapping uranium from surface waters. Among them, natural systems containing amorphous silica are poorly documented. A former study from the environment of the Peny mine (France) showed the importance of silica in uranium speciation [1]. The Nopal uranium deposit is located in volcanic tuff from tertiary period. It hosted several hydrothermal alteration episodes responsible for clay minerals formation. A primary uranium mineralisation occurred in a breccia pipe, consisting in uraninite, subsequently altered in secondary uranium minerals among which several silicates. Eventually, opal was formed and coated uranyl silicates such as uranophane and weeksite [2], [3]. Opals also contain minor amounts of uranium. The Nopal deposit is still considered as a natural analogue of high level nuclear waste repository located in volcanic tuff. It may be used to reveal the low temperature conditions of trapping of uranium in systems devoid of iron oxides such as silica-containing ones. The aim of this study is then to determine the uranium speciation, and its possible complexity, associated to these opals that represent a late trapping episode. It will provide insights ranging from the micrometer scale of electron microscopies to the molecular scale provided by fluorescence spectroscopy. Three samples of green or yellow opals have been analysed by a combination of complementary tools including scanning electron microscopy (SEM) on cross-sections, transmission electron microscopy (TEM) on focused ion beam (FIB) films, cathodoluminescence and time-resolved laser fluorescence spectroscopy (TRLFS). Uranium speciation was found to be complex. We first evidence U-bearing microparticles of beta-uranophane Ca[(UO2)(Si

  4. Microscopic potential fluctuations in Si-doped AlGaN epitaxial layers with various AlN molar fractions and Si concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kurai, Satoshi, E-mail: kurai@yamaguchi-u.ac.jp; Yamada, Yoichi [Department of Material Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611 (Japan); Miyake, Hideto; Hiramatsu, Kazumasa [Department of Electrical and Electronic Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507 (Japan)

    2016-01-14

    Nanoscopic potential fluctuations of Si-doped AlGaN epitaxial layers with the AlN molar fraction varying from 0.42 to 0.95 and Si-doped Al{sub 0.61}Ga{sub 0.39}N epitaxial layers with Si concentrations of 3.0–37 × 10{sup 17 }cm{sup −3} were investigated by cathodoluminescence (CL) imaging combined with scanning electron microscopy. The spot CL linewidths of AlGaN epitaxial layers broadened as the AlN molar fraction was increased to 0.7, and then narrowed at higher AlN molar fractions. The experimental linewidths were compared with the theoretical prediction from the alloy broadening model. The trends displayed by our spot CL linewidths were consistent with calculated results at AlN molar fractions of less than about 0.60, but the spot CL linewidths were markedly broader than the calculated linewidths at higher AlN molar fractions. The dependence of the difference between the spot CL linewidth and calculated line broadening on AlN molar fraction was found to be similar to the dependence of reported S values, indicating that the vacancy clusters acted as the origin of additional line broadening at high AlN molar fractions. The spot CL linewidths of Al{sub 0.61}Ga{sub 0.39}N epitaxial layers with the same Al concentration and different Si concentrations were nearly constant in the entire Si concentration range tested. From the comparison of reported S values, the increase of V{sub Al} did not contribute to the linewidth broadening, unlike the case of the V{sub Al} clusters.

  5. LA-ICP-MS zircon U-Pb dating and phenocryst EPMA of dikes, Guocheng, Jiaodong Peninsula: Implications for North China Craton lithosphere evolution

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Widespread dike swarm, including diorite-, monzonite-porphyry and lamprophyre, intruded in the al- tered breccia gold deposits along basin marginal faults, Guocheng, Jiaodong Peninsula. Petrography exhibits biotite enclaves in amphibole phenocrysts and the presence of acicular apatites in these dikes. Electron probe microanalyses (EPMA) show that the amphibole and clinopyroxene phenocryst’s mantle in diorite porphyry and lamprophyre respectively has sharply higher MgO (Mg#) and Cr2O3 contents in contrast to their cores. The plagioclase phenocryst in monzonite porphyry has reverse zoning. These results indicate that the magma mixing between mantle-derived mafic and crust-derived felsic magmas occurred in the original process of the dikes. Zircon cathodoluminescence (CL) images show well-developed magmatic oscillatory zones and the acquired LA-ICP-MS zircon U-Pb weighted mean 206Pb/238U ages are 114±2 Ma (MSDW=1.5) for monzonite porphyry (GS1) and 116±1 Ma (MSDW=0.8) for diorite porphyry (GS2), respectively. Earlier magmatic events in the northwest Jiaodong Peninsula represented by some inherited or captured zircons also occur in these dikes. Magmatic zircons from GS1 and GS2 display consistent chondrite-normalized REE patterns and Nb/Ta values, implying that they may share a similar or same source. HREE enrichment and obvious negative Eu anomalies of these zircons preclude garnet presented in their source. Our results, combined with preciously pub- lished data, indicate that dike intrusion and gold mineralization among quartz vein, altered tectonite and altered breccia gold deposits are broadly contemporaneous throughout the Jiaodong Peninsula. These also imply that the intensive crust-mantle interaction and asthenospheric underplating had oc- curred in the Early Cretaceous in the Peninsula, together with foundering of lower crust in the early Mesozoic, representing the different stages of lithosphere thinning in the North China Craton (NNC).

  6. Fabrication and luminescence properties of one-dimensional CaMoO(4): Ln(3+) (Ln = Eu, Tb, Dy) nanofibers via electrospinning process.

    Science.gov (United States)

    Hou, Zhiyao; Chai, Ruitao; Zhang, Milin; Zhang, Cuimiao; Chong, Peng; Xu, Zhenhe; Li, Guogang; Lin, Jun

    2009-10-20

    One-dimensional CaMoO(4):Ln(3+) (Ln = Eu, Tb, Dy) nanofibers have been prepared by a combination method of sol-gel and electrospinning process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and low voltage cathodoluminescence (CL) as well as kinetic decays were used to characterize the resulting samples. SEM and TEM analyses indicate that the obtained precursor fibers have a uniform size, and the as-formed CaMoO(4):Ln(3+) nanofibers consist of nanoparticles. Under ultraviolet excitation, the CaMoO(4) samples exhibit a blue-green emission band with a maximum at 500 nm originating from the MoO(4)(2-) groups. Due to an efficient energy transfer from molybdate groups to dopants, CaMoO(4):Ln(3+) phosphors show their strong characteristic emission under ultraviolet excitation and low-voltage electron beam excitation. The energy transfer process was further studied by the emission spectra and the kinetic decay curves of Ln(3+) upon excitation into the MoO(4)(2-) groups in the CaMoO(4):x mol % Ln(3+) samples (x = 0-5). Furthermore, the emission colors of CaMoO(4):Ln(3+) nanofibers can be tuned from blue-green to green, yellow, and orange-red easily by changing the doping concentrations (x) of Ln(3+) ions, making the materials have potential applications in fluorescent lamps and field emission displays (FEDs).

  7. Abnormal selective area growth of irregularly-shaped GaN structures on the apex of GaN pyramids and its application for wide spectral emission

    Science.gov (United States)

    Yu, Yeon Su; Lee, Jun Hyeong; Ahn, Hyung Soo; Yang, Min

    2014-12-01

    We report on the growth and the characterization of three-dimensional randomly-shaped InGaN/GaN structures selectively grown on the apex of GaN pyramids for the purpose of enlarging the emission spectral range. We found that the variations in the shape and the size of the three-dimensional GaN structures depend on the growth temperature and the surface area for selective growth under intentional turbulence in the gas stream. The selectively grown GaN structures grown at 1020 °C have irregular shape, while the samples grown at 1100 °C have rather uniform hexagonal pyramidal shapes. Irregularly shaped GaN structures were also obtained on the apex of GaN pyramids when the SiO2 mask was removed to 1/10 of the total height of the underlying GaN pyramid. When only 1/5 of the SiO2 mask was removed, however, the selectively grown GaN structures had similar hexagonal pyramidal shapes resembling those of the underlying GaN pyramids. The CL (Cathodoluminescence) spectra of the InGaN layers grown on the randomly shaped GaN structures showed a wide emission spectral range from 388 to 433 nm due to the non-uniform thickness and spatially inhomogeneous indium composition of the InGaN layers. This new selective growth method might have great potential for applications of non-phosphor white light emitting diodes (LEDs) with optimized growth conditions for InGaN active layers of high indium composition and with optimum process for fabrication of electrodes for electrical injection.

  8. Growth Kinematics of Opening-Mode Fractures

    Science.gov (United States)

    Eichhubl, P.; Alzayer, Y.; Laubach, S.; Fall, A.

    2014-12-01

    Fracture aperture is a primary control on flow in fractured reservoirs of low matrix permeability including unconventional oil and gas reservoirs and most geothermal systems. Guided by principles of linear elastic fracture mechanics, fracture aperture is generally assumed to be a linear function of fracture length and elastic material properties. Natural opening-mode fractures with significant preserved aperture are observed in core and outcrop indicative of fracture opening strain accommodated by permanent solution-precipitation creep. Fracture opening may thus be decoupled from length growth if the material effectively weakens after initial elastic fracture growth by either non-elastic deformation processes or changes in elastic properties. To investigate the kinematics of fracture length and aperture growth, we reconstructed the opening history of three opening-mode fractures that are bridged by crack-seal quartz cement in Travis Peak Sandstone of the SFOT-1 well, East Texas. Similar crack-seal cement bridges had been interpreted to form by repeated incremental fracture opening and subsequent precipitation of quartz cement. We imaged crack-seal cement textures for bridges sampled at varying distance from the tips using scanning electron microscope cathodoluminescence, and determined the number and thickness of crack-seal cement increments as a function of position along the fracture length and height. Observed trends in increment number and thickness are consistent with an initial stage of fast fracture propagation relative to aperture growth, followed by a stage of slow propagation and pronounced aperture growth. Consistent with fluid inclusion observations indicative of fracture opening and propagation occurring over 30-40 m.y., we interpret the second phase of pronounced aperture growth to result from fracture opening strain accommodated by solution-precipitation creep and concurrent slow, possibly subcritical, fracture propagation. Similar deformation

  9. Atmospheric scanning electron microscope system with an open sample chamber: Configuration and applications

    Energy Technology Data Exchange (ETDEWEB)

    Nishiyama, Hidetoshi, E-mail: hinishiy@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Koizumi, Mitsuru, E-mail: koizumi@jeol.co.jp [JEOL Technics Ltd., 2-6-38 Musashino, Akishima, Tokyo 196-0021 (Japan); Ogawa, Koji, E-mail: kogawa@jeol.co.jp [JEOL Technics Ltd., 2-6-38 Musashino, Akishima, Tokyo 196-0021 (Japan); Kitamura, Shinich, E-mail: kitamura@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Konyuba, Yuji, E-mail: ykonyuub@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Watanabe, Yoshiyuki, E-mail: watanabeyoshiy@pref.yamagata.jp [Yamagata Research Institute of Technology, 2-2-1, Matsuei, Yamagata 990-2473 (Japan); Ohbayashi, Norihiko, E-mail: n.ohbayashi@m.tohoku.ac.jp [Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Fukuda, Mitsunori, E-mail: nori@m.tohoku.ac.jp [Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Suga, Mitsuo, E-mail: msuga@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Sato, Chikara, E-mail: ti-sato@aist.go.jp [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-4, Umezono, Tsukuba 305-8568 (Japan)

    2014-12-15

    An atmospheric scanning electron microscope (ASEM) with an open sample chamber and optical microscope (OM) is described and recent developments are reported. In this ClairScope system, the base of the open sample dish is sealed to the top of the inverted SEM column, allowing the liquid-immersed sample to be observed by OM from above and by SEM from below. The optical axes of the two microscopes are aligned, ensuring that the same sample areas are imaged to realize quasi-simultaneous correlative microscopy in solution. For example, the cathodoluminescence of ZnO particles was directly demonstrated. The improved system has (i) a fully motorized sample stage, (ii) a column protection system in the case of accidental window breakage, and (iii) an OM/SEM operation system controlled by a graphical user interface. The open sample chamber allows the external administration of reagents during sample observation. We monitored the influence of added NaCl on the random motion of silica particles in liquid. Further, using fluorescence as a transfection marker, the effect of small interfering RNA-mediated knockdown of endogenous Varp on Tyrp1 trafficking in melanocytes was examined. A temperature-regulated titanium ASEM dish allowed the dynamic observation of colloidal silver nanoparticles as they were heated to 240 °C and sintered. - Highlights: • Atmospheric SEM (ASEM) allows observation of samples in liquid or gas. • Open sample chamber allows in situ monitoring of evaporation and sintering processes. • in situ monitoring of processes during reagent administration is also accomplished. • Protection system for film breakage is developed for ASEM. • Usability of ASEM has been improved significantly including GUI control.

  10. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  11. Facile patterning of luminescent GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) thin films by microcontact printing process

    Energy Technology Data Exchange (ETDEWEB)

    Wang Dong; Yang Piaoping; Cheng Ziyong, E-mail: zycheng@ciac.jl.cn; Wang Wenxin; Ma Pingan; Zhai Xuefeng; Lin Jun, E-mail: jlin@ciac.jl.cn [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, State Key Laboratory of Rare Earth Resource Utilization (China)

    2012-01-15

    Ordered arrays of luminescent GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) films with dot patterns have been successfully fabricated via microcontact printing method. The soft-lithography process utilizes a PDMS elastomeric mold as the stamp combined with a Pechini-type sol-gel process to produce luminescent patterns on quartz plates, in which a GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) precursor solution was employed as ink. The ordered luminescent GdVO{sub 4}:Ln patterns were revealed by optical microscopy and their microstructure, consisting of nanometer-scale particles, as demonstrated by scanning electronic microscopy observations. In addition, photoluminescence and cathodoluminescence were carried out to characterize the patterned GdVO{sub 4}:Ln (Ln = Eu{sup 3+}, Dy{sup 3+}, Sm{sup 3+}) samples. Upon UV-light or electron-beam irradiation, the rare earth ions Eu{sup 3+}, Dy{sup 3+}, and Sm{sup 3+} in the crystalline GdVO{sub 4} host show their characteristic transitions dominated by {sup 5}D{sub 0}-{sup 7}F{sub 2}, {sup 4}F{sub 9/2}-{sup 6}H{sub 13/2} ,and {sup 4}G{sub 5/2}-{sup 6}H{sub 7/2}, respectively. These results make the combining soft lithography with a Pechini-type sol-gel route have potential applications as rare-earth luminescent pixels for next-generation field-emission display devices.

  12. Protolith ages and timing of peak and retrograde metamorphism of the high-pressure granulites in the Shandong Peninsula, eastern North China Craton

    Directory of Open Access Journals (Sweden)

    Pinghua Liu

    2012-11-01

    Full Text Available High-pressure (HP granulites widely occur as enclaves within tonalite-trondhjemite-granodiorite (TTG gneisses of the Early Precambrian metamorphic basement in the Shandong Peninsula, southeast part of the North China Craton (NCC. Based on cathodoluminescence (CL, laser Raman spectroscopy and in-situ U-Pb dating, we characterize the zircons from the HP granulites and group them into three main types: inherited (magmatic zircon, HP metamorphic zircon and retrograde zircon. The inherited zircons with clear or weakly defined magmatic zoning contain inclusions of apatites, and 207Pb/206Pb ages of 2915–2890 Ma and 2763–2510 Ma, correlating with two magmatic events in the Archaean basement. The homogeneous HP metamorphic zircons contain index minerals of high-pressure metamorphism including garnet, clinopyroxene, plagioclase, quartz, rutile and apatite, and yield 207Pb/206Pb ages between 1900 and 1850 Ma, marking the timing of peak HP granulite facies metamorphism. The retrograde zircons contain inclusions of orthopyroxene, plagioclase, quartz, apatite and amphibole, and yield the youngest 207Pb/206Pb ages of 1840–1820 Ma among the three groups, which we correlate to the medium to low-pressure granulite facies retrograde metamorphism. The data presented in this study suggest subduction of Meso- and Neoarchean magmatic protoliths to lower crust depths where they were subjected to HP granulite facies metamorphism during Palaeoproterozoic (1900–1850 Ma. Subsequently, the HP granulites were exhumated to upper crust levels, and were overprinted by medium to low-pressure granulite and amphibolite facies retrograde event at ca. 1840–820 Ma.

  13. Multitechnique characterization of lapis lazuli for provenance study.

    Science.gov (United States)

    Lo Giudice, Alessandro; Re, Alessandro; Calusi, Silvia; Giuntini, Lorenzo; Massi, Mirko; Olivero, Paolo; Pratesi, Giovanni; Albonico, Maria; Conz, Elisa

    2009-12-01

    Lapis lazuli is one of the oldest precious stone, being used for glyptic as early as 7,000 years ago: jewels, amulets, seals, and inlays are examples of objects produced using this material. Only a few sources of lapis lazuli exist in the world due to the low probability of geological conditions in which it can form, so that the possibility to associate the raw material to man-made objects helps to reconstruct trade routes. Since art objects produced using lapis lazuli are valuable, only nondestructive investigations can be carried out to identify the provenance of the raw materials. Ionoluminescence (IL) is a good candidate for this task. Similar to cathodoluminescence (CL), IL consists in the collection of luminescence spectra induced by megaelectronvolt ion (usually protons) irradiation. The main advantage of IL consists in the possibility of working in air while measuring simultaneously the composition of major and trace elements by means of complementary ion beam analysis techniques like particle-induced X-ray emission (PIXE) or particle-induced gamma-ray emission (PIGE). In the present work, a systematic study of the luminescence properties of lapis lazuli under charged particle irradiation is reported. In the first phase, a multitechnique approach was adopted (CL, scanning electron microscopy with microanalysis, micro-Raman) to characterize luminescent minerals. This characterization was propaedeutic for IL/PIXE/PIGE measurements carried out on significant areas selected on the basis of results obtained previously. Criteria to identify provenance of lapis lazuli from four of the main sources (Afghanistan, Pamir Mountains in Tajikistan, Chile, and Siberia) were proposed.

  14. Spectral and surface investigations of Ca{sub 2}V{sub 2}O{sub 7}:Eu{sup 3+} nanophosphors prepared by citrate-gel combustion method: a potential red-emitting phosphor for near-UV light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinay [Shri Mata Vaishno Devi University, School of Physics, Katra, J and K (India); University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa); Bedyal, A.K.; Sharma, J. [Shri Mata Vaishno Devi University, School of Physics, Katra, J and K (India); Kumar, V.; Ntwaeaborwa, O.M.; Swart, H.C. [University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa)

    2014-09-15

    In the present work, red-emitting Ca{sub 2}V{sub 2}O{sub 7}:xEu{sup 3+} (x = 0.5-6.0 mol%) nanophosphors, in the form of powders, were synthesized by the citrate-gel combustion method using metal nitrates as precursors and citric acid as fuel. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy, photoluminescence (PL) and cathodoluminescence (CL) spectroscopy were used to study the structure, morphology and spectral properties of the samples. The chemical compositions and electronic states of the powders were analyzed with X-ray photoelectron spectroscopy. The average crystallite sizes estimated using the XRD data were found to be in the range of 30-45 nm, and were cross verified by TEM. The lattice parameters determined by the POWD program were approximated as a = 7.242 Aa, b = 6.674 Aa, c = 6.932 Aa and V = 291.24 Aa{sup 3}, respectively. Under UV (395 nm) (PL) and electron (CL) excitation, the nanophosphors show characteristic emission from the Eu{sup 3+} ion ({sup 5}D{sub 0} → {sup 7}F{sub j}, j = 1-5) with the main peaks at 612 and 616 nm. The maximum emission intensity was recorded from the sample with an Eu{sup 3+} concentration of 4 mol% and a critical energy distance of 19.084 Aa between the donor and the acceptor. Above this concentration, there was a reduction in the intensity due to dipole-dipole induced concentration quenching effects. The potential applications of this phosphor as a high color-purity phosphor in light-emitting diodes are evaluated. (orig.)

  15. Origin and role of fluids involved in the seismic cycle of extensional faults in carbonate rocks

    Science.gov (United States)

    Smeraglia, Luca; Berra, Fabrizio; Billi, Andrea; Boschi, Chiara; Carminati, Eugenio; Doglioni, Carlo

    2016-09-01

    We examine the potentially-seismic right-lateral transtensional-extensional Tre Monti Fault (central Apennines, Italy) with structural and geochemical methods and develop a conceptual evolutionary model of extensional faulting with fluid involvement in shallow (≤3 km depth) faults in carbonate rocks. In the analysed fault zone, multiscale fault rock structures include injection veins, fluidized ultracataclasite layers, and crackle breccias, suggesting that the fault slipped seismically. We reconstructed the relative chronology of these structures through cross-cutting relationship and cathodoluminescence analyses. We then used C- and O-isotope data from different generations of fault-related mineralizations to show a shift from connate (marine-derived) to meteoric fluid circulation during exhumation from 3 to ≤1 km depths and concurrent fluid cooling from ∼68 to hydrological system, where prevalently connate fluids circulated within the fault zone at temperatures between 60° and 75 °C. During fault zone exhumation, at depths ≤1 km and temperatures hydrological circulation became open and meteoric-derived fluids progressively infiltrated and circulated within the fault zone. The role of these fluids during syn-exhumation seismic cycles of the Tre Monti Fault has been substantially passive along the whole fault zone, the fluids being passively redistributed at hydrostatic pressure following co-seismic dilatancy. Only the principal fault has been characterized, locally and transiently, by fluid overpressures. The presence of low-permeability clayey layers in the sedimentary sequence contributed to control the type of fluids infiltrating into the fault zone and possibly their transient overpressures. These results can foster the comprehension of seismic faulting at shallow depths in carbonate rocks of other fold-thrust belts involved in post-collisional seismogenic extensional tectonics.

  16. LA-ICP-MS zircon U-Pb dating and phenocryst of dikes, Guocheng, Jiaodong Peninsula: Implications for North China Craton lithosphere evolution

    Institute of Scientific and Technical Information of China (English)

    TAN Jun; WEI JunHao; GUO LingLi; ZHANG KeQing; YAO ChunLiang; LU JianPei; LI HongMei

    2008-01-01

    Widespread dike swarm, including diorite-, monzonite-porphyry and lamprophyre, intruded in the altered breccia gold deposits along basin marginal faults, Guocheng, Jiaodong Peninsula. Petrography exhibits biotite enclaves in amphibole phenocrysts and the presence of acicular apatites in these dikes.Electron probe microanalyses (EPMA) show that the amphibole and clinopyroxene phenocryst's mantle in diorite porphyry and lamprophyre respectively has sharply higher MgO (Mg#) and Cr203 contents in contrast to their cores. The plagioclase phenocryst in monzonite porphyry has reverse zoning. These results indicate that the magma mixing between mantle-derived mafic and crust-derived felsic magmas occurred in the original process of the dikes. Zircon cathodoluminescence (CL) images show well-developed magmatic oscillatory zones and the acquired LA-ICP-MS zircon U-Pb weighted mean 206pb/238U ages are 114±2 Ma (MSDW=1.5) for monzonite porphyry (GS1) and 116±1 Ma (MSDW=0.8) for diorite porphyry (GS2), respectively. Earlier magmatic events in the northwest Jiaodong Peninsula represented by some inherited or captured zircons also occur in these dikes. Magmatic zircons from GSl and GS2 display consistent chondrite-normalized REE patterns and Nb/Ta values, implying that they may share a similar or same source. HREE enrichment and obvious negative Eu anomalies of these zircons preclude garnet presented in their source. Our results, combined with preciously published data, indicate that dike intrusion and gold mineralization among quartz vein, altered tectonite and altered breccia gold deposits are broadly contemporaneous throughout the Jiaodong Peninsula.These also imply that the intensive crust-mantle interaction and asthenospheric underplating had occurred in the Early Cretaceous in the Peninsula, together with foundering of lower crust in the early Mesozoic, representing the different stages of lithosphere thinning in the North China Craton (NNC).

  17. SHRIMP U-Pb zircon age of tuff from the Kunyang Group in central Yunnan: Evidence for Grenvillian orogeny in South China

    Institute of Scientific and Technical Information of China (English)

    ZHANG ChuanHeng; GAO LinZhi; WU ZhenJie; SHI XiaoYing; YAN QuanRen; LI DaJian

    2007-01-01

    Whether or not Grenvillian orogeny occurred in South China still remains highly controversial because high-quality, discriminating data are lacking, and therefore, the key to resolve this matter is to find datable volcanic and/or sedimentary rocks related to Grenvillian orogeny. Such rocks are apparently present in the Fuliangpeng Member from the lower-middle part of Kunyang Group in central Yunnan;here the unit is more than 100 m thick and consists of andesitic ignimbrite, tuffite, terrigeous clastic rocks and carbonates. These volcanic rocks, developed south of the Sibao fold-thrust belts, represent the earliest calc-alkaline volcanic activity in late Precambrian time from central Yunnan and are coeval with both a change in sedimentary facies from detritus to carbonates and the beginning of seismite development elsewhere. Two samples for SHRIMP analysis were collected from this volcanic unit.Sample G3-29-2, from the bottom of Fuliangpeng Member, is an ignimbrite, and about 100 zircon crystals recovered from it have euhedral shapes and display relatively simple sector zonation under cathodoluminescent (CL) imaging, suggesting a magmatogenic origin. Twenty-five of the zircons were analyzed and a weighed-mean U-Pb age of 1032±9 Ma was obtained. Sample G3-29-3 from uppermost part of Fuliangpeng Member is a tuffite, and many rounded, evidently detrital zircons were recovered.Nine of these zircons were analyzed, and the oldest single-grain U-Pb zircon age is 1938±26 Ma, implying that Paleoproterozoic basement developed in Cathaysia. The dating result, combined with the geotectonic research on the Fuliangpeng Member, leads us to conclude that late Mesoproterozoic orogenic volcanic activity occurred in the western part of South China, and that the related collision of Yangtze and Cathaysian cratons was an integral part of the assembly of Rodinia.

  18. The Use and Abuse of Th-U Ratios in the Interpretation of Zircon

    Science.gov (United States)

    Möller, A.; ÓBrien, P. J.; Kennedy, A.; Kröner, A.

    2003-04-01

    In the interpretation of geochronological data the distinction between magmatic and metamorphic zircon is mainly based on morphology, internal zoning or Th-U ratio. This distinction is of doubtful benefit in partially molten high grade metamorphic rocks where partial melting and zircon growth or dissolution may have occurred in several phases. It is proposed that instead of classifying zircon into magmatic and metamorphic groups, differences and changes in chemistry from inherited core to overgrowth can be attributed to growth or recrystallization mechanisms. Taking the distinction literally, only zircon grown by solid state (metamorphic) reactions may be called metamorphic, whereas zircon crystallized from melt is magmatic, and zircon crystallized from fluids is hydrothermal. Trace element characteristics together with the criteria mentioned above may help to link zircon growth to these environments or to other processes altering existing zircon (i.e. metamictisation, annealing, recrystallization, dissolution-reprecipitation). In-situ ion microprobe analysis has been used to track Th-U ratios of zircon through time in polymetamorphic rocks. Several different trends can be distinguished and attributed to different growth mechanisms when combined with cathodo-luminescence and backscatter electron imaging. Unchanged Th/U through time is interpreted to reflect closed system behaviour, lower Th/U in overgrowths can indicate competition for Th with high Th minerals (monazite, allanite etc.), higher Th/U is also observed and interpreted to reflect open system behaviour, breakdown of minerals with high Th/U, or competition with high U minerals (e.g. xenotime). In summary, zircon grown during metamorphic events may not be characterized by low Th/U, and classifying zircon as "metamorphic" solely based on its Th/U as occasionally seen in the literature can lead to gross misinterpretations.

  19. Low-Temperature Plasticity of Naturally Deformed Calcite Rocks

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Optical, cathodoluminescence and transmission electron microscope (TEM) analyses were conducted onfour groups of calcite fault rocks, a cataclastic limestone, cataclastic coarse-grained marbles from two fault zones, and afractured mylonite. These fault rocks show similar microstructural characteristics and give clues to similar processes ofrock deformation. They are characterized by the structural contrast between macroscopic cataclastic (brittle) andmicroscopic mylonitic (ductile) microstructures. Intragranular deformation microstructures (i.e. deformation twins, kinkbands and microfractures) are well preserved in the deformed grains in clasts or in primary rocks. The matrix materials areof extremely fine grains with diffusive features. Dislocation microstructures for co-existing brittle deformation andcrystalline plasticity were revealed using TEM. Tangled dislocations are often preserved at the cores of highly deformedclasts, while dislocation walls form in the transitions to the fine-grained matrix materials and free dislocations, dislocationloops and dislocation dipoles are observed both in the deformed clasts and in the fine-grained matrix materials. Dynamicrecrystallization grains from subgrain rotation recrystallization and subsequent grain boundary migration constitute themajor parts of the matrix materials. Statistical measurements of densities of free dislocations, grain sizes of subgrains anddynamically recrystallized grains suggest an unsteady state of the rock deformation. Microstructural andcathodoluminescence analyses prove that fluid activity is one of the major parts of faulting processes. Low-temperatureplasticity, and thereby induced co-existence of macroscopic brittle and microscopic ductile microstmctures are attributedto hydrolytic weakening due to the involvement of fluid phases in deformation and subsequent variation of rock rheology.During hydrolytic weakening, fluid phases, e.g. water, enhance the rate of dislocation slip and climb, and

  20. Paleoproterozoic, High-Metamorphic, Metasedimentary Units of Siberian Craton

    Institute of Scientific and Technical Information of China (English)

    Lena URMANTSEVA; Olga TURKINA

    2009-01-01

    Sensitive, high-resointion ion microprobe zircon U-Pb ages of Paleoproterozoic, high-grade,metasedimentary rocks from the south-western part of the Siberian Craton are reported. Early Precambrian, high-grade complexes, including garnet-biotite, hypersthene-biotite, and cordierite-bearing gneisses compose the Irkut terrane of the Sharyzhalgay Uplift. Protoliths of studied gneisses correspond to terrigenous sediments, ranging from greywacke to shale. The paragneiss model Nd ages of 2.4-3.1 Ga indicate Archean-to-Paleoproterozoic source provinces. Zircons from gneisses show core-rim textures in cathodoluminescence (CL) image. Round or irregular shaped cores indicate detrital origin. Structureless rims with low Th/U are metamorphic in origin. The three age groups of detrital cores are: ≥2.7, -2.3, and 1.95-2 Ga. The ages of metamorphic rims range from 1.86 to 1.85 Ga;therefore, the sediments were deposited between 1.95 and 1.86 Ga and derived from Archean and Paleoproterozoic source rocks. It should be noted that Paleoproterozoic metasedimentary rocks of the Irkut Block are not unique. High-grade metaterrigenons sediments, with model Nd ages ranging from 2.3 to 2.5 Ga, are widely distributed within the AIdan and Anabar Shields of the Siberian Craton. The same situation is observed in the North China Craton, where metasedimentary rocks contain detrital igneous zircon grains with ages ranging from 3 to 2.1 Ga (Wan et al., 2006). All of these sedimentary units were subjected to Late Paleoproterozoic metamorphism. In the Siberian Craton, the Paleoproterozoic sedimentary deposits are possibly marked passive margins of the Early Precambrian crustal blocks, and their high-grade metamorphism was related to the consolidation of the Siberian Craton.

  1. Polarized light from excitonic recombination in selectively etched GaN/AlN quantum dot ensembles on Si(111)

    Science.gov (United States)

    Moshe, O.; Rich, D. H.; Damilano, B.; Massies, J.

    2011-12-01

    Multiple layers of GaN/AlN quantum dot (QD) ensembles were grown by the Stranski-Krastanov method on Si(111) using molecular beam epitaxy. During the subsequent cooling from growth temperature, the thermal expansion coefficient mismatch between the Si substrate and GaN/AlN film containing the vertically stacked QDs leads to an additional biaxial tensile stress of 20-30 kbar in the III-nitride film. We have selectively modified the thermal stress in the QD layers by etching a cross-hatched pattern into the as-grown sample using inductively coupled Cl2/Ar plasma reactive ion etching. The results show that a suitable choice of stripe width from ˜2 to 10 µm and orientation along [11-20] and [1-100] can create regions of in-plane uniaxial stress that enable a selective and local control of the polarized luminescence from ensembles of QDs which were probed with cathodoluminescence. Experimental results indicate that the polarization anisotropy vanishes at high temperatures (˜300 K) with an increasing e-h pair excitation for the QDs, while the anisotropy decreases more slowly with excitation at low temperatures (˜46 K). A theoretical modelling of the effect of carrier filling on the polarization anisotropy and the excitonic transition energy was performed, as based on three-dimensional self-consistent solutions of the Schrödinger and Poisson equations using the 6{\\times} 6\\ \\bit{k}{\\bdot}\\bit{p} and effective-mass methods for calculations of the e-h wavefunctions and electron and hole quasi-Fermi levels for varying levels of state filling. We attribute carrier filling and a thermal excitation of holes into higher energy QD hole states during e-h pair excitation to account for the observed gradual decrease in the polarization anisotropy with an increasing e-h pair excitation density at T = 300 K.

  2. Authigenic albite formation due to water-rock interactions - Case study: Magnus oilfield (UK, Northern North Sea)

    Science.gov (United States)

    Mu, Nana; Fu, Yunjiao; Schulz, Hans-Martin; van Berk, Wolfgang

    2016-01-01

    It is the aim of this contribution to test whether organic-inorganic interactions could induce the formation of authigenic albite. This concept and related results are being compared with modelling scenarios which are purely based on inorganic geochemical reactions. In order to unravel the pathway of authigenic albite formation, this paper presents results of a multidisciplinary study from imaging, geochemistry, mineralogy, and hydrogeochemical modelling. The Jurassic reservoir sandstones of the Magnus oilfield (UK, North Sea) were chosen as a test site. Albite occurs with 4-18 wt.% in the Magnus sandstones and its contents vary with depth. However, albite contents increase with increasing K-feldspar contents and decreasing grain size. It occurs in three forms: (1) as lamellae in perthite, (2) as overgrowth on/in corroded feldspar, and, (3) as cloudy replacing albite patches in K-feldspar. The albite overgrowth has the highest chemical purity (100% albite) whilst albite lamellae and replacing albite patches are slightly less pure (containing 1-4% anorthite). Albite appears non-altered, and has a euhedral morphology and dull cathodoluminescence. It commonly co-occurs with corroded K-feldspar grains. The precipitation of diagenetic albite in the Magnus sandstones is attributed to deep burial 80 Ma ago and may have continued until today at temperatures between 90-120 °C. The results of hydrogeochemical modelling offer two possible pathways for the authigenic albite formation: (1) Dissolution of unstable minerals (such as kaolinite and chalcedony) coupled to reduction of ferric iron minerals by products generated during oil generation, migration and degradation; (2) Dissolution of non-end member feldspar, such as K-feldspar with 10% albite, coupled to illite formation can account for trace amounts of albite due to an elevated Na+/K+ activity ratio in the pore water.

  3. Titanium and oxygen isotope diffusion in quartz-phenocrysts from a Jurassic rhyolite, Chon Aike Province (Fitz Roy, Patagonia)

    Science.gov (United States)

    Seitz, S.; Putlitz, B.; Baumgartner, L. P.; Escrig, S.; Meibom, A.; Leresche, S.; Vennemann, T. W.

    2014-12-01

    The volcanic El Quemado Complex was deposited during the breakup of Gondwana during the Middle and Late Jurassic. It is part of a large silicic igneous province, which includes the Chon Aike Province in Southern Patagonia and related rocks from the Antarctic Peninsula [1]. The Complex consists of rhyolitic and dacitic ignimbrites and air-fall tuffs, intercalated with andesitic to rhyolitic lava flows. New LA-ICPMS U/Pb-dates of zircons from the Fitz Roy area yield ages between 148 and 153Ma. No inherited zircons were found, suggesting that the temperature of 850°C calculated from zircon saturation is a minimum temperature. Lava flows are typically rich in quartz phenocrysts, which preserved magmatic trace element zoning, as revealed by cathodoluminescence (CL): light cores are surrounded by several darker and lighter zones towards the rim. The δ18O-values for quartz of between 11 to 14 ‰ are compatible with a crustal source for the magma and the SIMS analyses of phenocrysts reveal no zoning in O-isotope compositions. High-resolution Ti-profiles were obtained by NanoSIMS with a beam size of ~200 nm and a minimum step size of ~120 nm. Several lines perpendicular to the magmatic zoning of the quartz-phenocrysts were measured. The profiles show sharp changes in the 48Ti/29Si-ratio over a distance of 5 μm, which correlate with CL-intensity changes. The profiles can be used for diffusion chronometry. The distances obtained from NanoSIMS profiles were used to calculate maximum diffusional relaxation times. Assuming a step function as initial condition and extrusion temperatures from zircon saturation of 850°C, we obtain a maximum residence time for the quartz-phenocrysts of 3.5 years. [1] Pankhurst R.J., Riley T.R., Fanning C.M., Kelley S.P., 2000. J. Pet., 41, 605-625.

  4. Geology of the Eoarchean, > 3.95 Ga, Nulliak supracrustal rocks in the Saglek Block, northern Labrador, Canada: The oldest geological evidence for plate tectonics

    Science.gov (United States)

    Komiya, Tsuyoshi; Yamamoto, Shinji; Aoki, Shogo; Sawaki, Yusuke; Ishikawa, Akira; Tashiro, Takayuki; Koshida, Keiko; Shimojo, Masanori; Aoki, Kazumasa; Collerson, Kenneth D.

    2015-11-01

    The Earth is a unique planet, which has been highly evolved, diversified and complicated through geologic time, and underwent many key events, including giant impact, magma ocean, core formation, large-scale mantle differentiation and late heavy bombardment, especially in its dawn. But, our knowledge of early Earth is limited due to the lack of the Hadean supracrustal rocks. The supracrustal rocks with the Eoarchean ages provide key evidence for the Earth's early evolution, but few supracrustal rocks have been comprehensively investigated. Therefore, we mapped in seven areas of the Saglek Block, northern Labrador, where ancient supracrustal sequences are interleaved with a diverse assemblage of orthogneisses. Early studies suggested that some of them have the Mesoarchean ages because of the lack of the Mesoarchean Saglek dyke, but we found the Saglek dykes in the areas to recognize the Eoarchean Nulliak supracrustal rocks and Uivak Gneiss in all the areas. Recent reassessment of U-Pb dating and cathodoluminescence observation of zircons from the oldest suites of the Uivak Gneiss showed that the Uivak Gneiss has the Eoarchean age, > 3.95 Ga, and forms the Iqaluk-Uivak Gneiss series. Because our geological survey clearly showed that the Iqaluk-Uivak Gneisses were intruded into the Nulliak supracrustal belts, the Nulliak supracrustal rocks are the oldest supracrustal rock in the world. The supracrustal belts consist of piles of fault-bounded blocks, which are composed of the ultramafic rocks, mafic rocks and sedimentary rocks in ascending order, similar to modern ocean plate stratigraphy (OPS). In addition, small-scale duplex structures are found over the areas. The presence of duplex structure and OPS indicates that the > 3.95 Ga Nulliak supracrustal belts originate from an accretionary complex. The presence of the accretionary complex, ophiolite and granitic continental crust provides the oldest evidence for the plate tectonics on the early Earth.

  5. Amorphous sub-nanometre Tb-doped SiO(x)N(y)/SiO2 superlattices for optoelectronics.

    Science.gov (United States)

    Ramírez, Joan Manel; Wojcik, Jacek; Berencén, Yonder; Ruiz-Caridad, Alícia; Estradé, Sònia; Peiró, Francesca; Mascher, Peter; Garrido, Blas

    2015-02-27

    Amorphous sub-nanometre Tb-doped SiOxNy/SiO2 superlattices were fabricated by means of alternating deposition of 0.7 nm thick Tb-doped SiOxNy layers and of 0.9 nm thick SiO2 barrier layers in an electron-cyclotron-resonance plasma enhanced chemical vapour deposition system with in situ Tb-doping capability. High resolution transmission electron microscopy images showed a well-preserved superlattice morphology after annealing at a high temperature of 1000 °C. In addition, transparent indium tin oxide (ITO) electrodes were deposited by electron beam evaporation using a shadow mask approach to allow for the optoelectronic characterization of superlattices. Tb(3+) luminescent spectral features were obtained using three different excitation sources: UV laser excitation (photoluminescence (PL)), under a bias voltage (electroluminescence (EL)) and under a highly energetic electron beam (cathodoluminescence (CL)). All techniques displayed Tb(3+) inner transitions belonging to (5)D4 levels except for the CL spectrum, in which (5)D3 transition levels were also observed. Two competing mechanisms were proposed to explain the spectral differences observed between PL (or EL) and CL excitation: the population rate of the (5)D3 state and the non-radiative relaxation rate of the (5)D3-(5)D4 transition due to a resonant OH-mode. Moreover, the large number of interfaces (trapping sites) that electrons have to get through was identified as the main reason for observing a bulk-limited charge transport mechanism governed by Poole-Frenkel conduction in the J-V characteristic. Finally, a linear EL-J dependence was measured, with independent spectral shape and an EL onset voltage as low as 6.7 V. These amorphous sub-nanometre superlattices are meant to provide low-cost solutions in different areas including sensing, photovoltaics or photonics.

  6. Detrital zircon geochronology and provenance of the Chubut Group in the northeast of Patagonia, Argentina

    Science.gov (United States)

    Navarro, Edgardo L.; Astini, Ricardo A.; Belousova, Elena; Guler, M. Verónica; Gehrels, George

    2015-11-01

    The Chubut Group constitutes the most widespread sedimentary unit in NE Patagonia, characterized by variable-energy fluvial deposits. U-Pb analysis of detrital zircons from two sections of the Chubut Group constraint the age of the oldest sedimentary rocks in the northeast of the Somuncurá - Cañadón Asfalto Basin. In the Cañadón Williams area, at San Jorge section, 20 km NW of Telsen locality, dating of 56 detrital zircons from a medium to coarse sandstone indicated a maximum depositional age of 109 ± 1 Ma (n = 4). These sandstones were interpreted to represent shallow channels, associated with a lacustrine system. In the Telsen locality, a laser ablation analysis of 115 detrital zircons from a medium to coarse-grained sandstone, from fluvial channel facies, yielded a maximum depositional age of ca. 106 ± 1 Ma (n = 8). Both ages are consistent with volcanic events of the Barremian to Albian age in the central Patagonian Andes Region. Cathodoluminescence images of zircons from the San Jorge sample suggest an igneous origin, which is further supported by Th/U values above 0.5 in most of the grains. The distribution of the statistical modes of the main age populations of detrital zircons for the two samples [182, 185 and 189 Ma for Telsen sample (T2S) and 181 ± 1 Ma for San Jorge sample (SJS)] matches the age of the volcanic Marifil Formation. The rocks of the Marifil Formation of these ages are exposed NE to SE of the study area. The abundance of zircons of similar Jurassic ages (n = 52 for SJS and n = 105 for T2S) and the external morphology of the zircons in the sample SJS, implies a close proximity of the source area. Suggestion that the Marifil Formation was the main provenance source is also supported by northeast-southeasterly paleocurrents measured at the San Jorge and Telsen sections.

  7. Influence of laser lift-off on optical and structural properties of InGaN/GaN vertical blue light emitting diodes

    Directory of Open Access Journals (Sweden)

    M. H. Doan

    2012-06-01

    Full Text Available The influences of the laser lift-off (LLO process on the InGaN/GaN blue light emitting diode (LED structures, grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition, have been comprehensively investigated. The vertical LED structures on Cu carriers are fabricated using electroplating, LLO, and inductively coupled plasma etching processes sequentially. A detailed study is performed on the variation of defect concentration and optical properties, before and after the LLO process, employing high-resolution transmission electron microscopy (HRTEM, scanning electron microscopy (SEM observations, cathodoluminescence (CL, photoluminescence (PL, and high-resolution X-ray diffraction (HRXRD measurements. The SEM observations on the distribution of dislocations after the LLO show well that even the GaN layer near to the multiple quantum wells (MQWs is damaged. The CL measurements reveal that the peak energy of the InGaN/GaN MQW emission exhibits a blue-shift after the LLO process in addition to a reduced intensity. These behaviors are attributed to a diffusion of indium through the defects created by the LLO and creation of non-radiative recombination centers. The observed phenomena thus suggest that the MQWs, the active region of the InGaN/GaN light emitting diodes, may be damaged by the LLO process when thickness of the GaN layer below the MQW is made to be 5 μm, a conventional thickness. The CL images on the boundary between the KrF irradiated and non-irradiated regions suggest that the propagation of the KrF laser beam and an accompanied recombination enhanced defect reaction, rather than the propagation of a thermal shock wave, are the main origin of the damage effects of the LLO process on the InGaN/GaN MQWs and the n-GaN layer as well.

  8. Controlled hydrothermal synthesis of BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composites exhibiting visible-light photocatalytic degradation of crystal violet

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yu-Rou; Lin, Ho-Pan [Department of Science Application and Dissemination, National Taichung University of Education, Taichung 403, Taiwan, ROC (China); Chung, Wen-Hsin [Department of Plant Pathology, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Dai, Yong-Ming [Department of Science Application and Dissemination, National Taichung University of Education, Taichung 403, Taiwan, ROC (China); Lin, Wan-Yu [Department of Plant Pathology, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Chen, Chiing-Chang, E-mail: ccchen@ms3.ntcu.edu.tw [Department of Science Application and Dissemination, National Taichung University of Education, Taichung 403, Taiwan, ROC (China)

    2015-02-11

    Highlights: • This is the first report on a series of BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} heterojunctions. • The BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composition was controlled by adjusting the growth parameters. • The BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} were indirect semiconductors with a 1.78–2.95-eV bandgap. • The new photocatalysts removed CV at a much faster rate than TiO{sub 2}. • Mechanisms were determined by separating the intermediates using HPLC-MS. - Abstract: A series of BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composites were prepared using autoclave hydrothermal methods. The composition and morphologies of the BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composites were controlled by adjusting the experimental conditions: the reaction pH value, temperature, and KCl/KI molar ratio. The products were characterized using X-ray diffraction, scanning electron microscopy-electron dispersive X-ray spectroscopy, UV–vis diffuse reflectance spectroscopy, Brunauer–Emmett–Teller specific surface areas, cathodoluminescence, high-resolution transmission electron microscopy, and high-resolution X-ray photoelectron spectroscopy. The photocatalytic efficiencies of composite powder suspensions were evaluated by monitoring the crystal violet (CV) concentrations. In addition, the quenching effects of various scavengers indicated that the reactive O{sub 2}·{sup −} played a major role, and OH· or h{sup +} played a minor role in CV degradation. The intermediates formed during the decomposition process were isolated, identified, and characterized using high performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry to elucidate the CV decomposition mechanism.

  9. Dolomitization of carbonated reservoirs of platforms. From geologic data to modeling. Example of the great Bahama bank; La dolomitisation des reservoirs carbonates de plate-forme. Des donnees geologiques a la modelisation. Exemple du Grand Banc des Bahamas

    Energy Technology Data Exchange (ETDEWEB)

    Caspard, E.

    2002-09-01

    Dolomitization has long been one of the most studied geological processes because of its economic interest (dolomitic rocks form a significant share of hydrocarbon reservoirs) as well as its academic interest, based on the fact that dolomite scarcely forms in current and recent marine environments whereas seawater is highly over-saturated; and that it is still not possible to synthesize it in laboratory under the same conditions. We used data collected by the University of Miami (Bahamas Drilling Project, ODP Leg 166) to understand the geological context of complete dolomitization of a Messinian 60 m thick reef unit. Classical methods of petrographic analysis of thin sections (optical microscopy, cathodoluminescence, scanning electron microscopy, in situ isotopic analyze using ionic microprobe) showed that the intensity of dolomitization is not controlled by the initial texture of the sediment, that the key parameter for dolomitization is the conservation of the initial mineralogy of magnesian bio-clasts, and that redox conditions, salinity and/or temperature of the precipitation fluid varied significantly during the process. Hydrodynamic modelling showed that during periods of high sea-level, Kohout thermal convection is a viable mechanism for driving marine fluids through the sediments. The key parameter for fluid circulations is the permeability anisotropy on the platform scale. Geochemical modelling showed that seawater is able to induce a complete dolomitization over durations of around one million years. Sensitivity tests showed that the critical parameter (as well as one of the less well-known) to describe diagenetic processes in carbonates is the water/rock reactions kinetics and in particular the precipitation kinetics of carbonate minerals. We finally propose that the dolomitization of the reef unit of the Unda well took place during the high sea-level period which extended over 1,1 My in the early Pliocene, according to the Kohout thermal convection

  10. High-quality uniaxial In(x)Ga(1-x)N/GaN multiple quantum well (MQW) nanowires (NWs) on Si(111) grown by metal-organic chemical vapor deposition (MOCVD) and light-emitting diode (LED) fabrication.

    Science.gov (United States)

    Ra, Yong-Ho; Navamathavan, R; Park, Ji-Hyeon; Lee, Cheul-Ro

    2013-03-01

    This article describes the growth and device characteristics of vertically aligned high-quality uniaxial p-GaN/InxGa1-xN/GaN multiple quantum wells (MQW)/n-GaN nanowires (NWs) on Si(111) substrates grown by metal-organic chemical vapor deposition (MOCVD) technique. The resultant nanowires (NWs), with a diameter of 200-250 nm, have an average length of 2 μm. The feasibility of growing high-quality NWs with well-controlled indium composition MQW structure is demonstrated. These resultant NWs grown on Si(111) substrates were utilized for fabricating vertical-type light-emitting diodes (LEDs). The steep and intense photoluminescence (PL) and cathodoluminescence (CL) spectra are observed, based on the strain-free NWs on Si(111) substrates. High-resolution transmission electron microscopy (HR-TEM) analysis revealed that the MQW NWs are grown along the c-plane with uniform thickness. The current-voltage (I-V) characteristics of these NWs exhibited typical p-n junction LEDs and showed a sharp onset voltage at 2.75 V in the forward bias. The output power is linearly increased with increasing current. The result indicates that the pulsed MOCVD technique is an effective method to grow uniaxial p-GaN/InxGa1-xN/GaN MQW/n-GaN NWs on Si(111), which is more advantageous than other growth techniques, such as molecular beam epitaxy. These results suggest the uniaxial NWs are promising to allow flat-band quantum structures, which can enhance the efficiency of LEDs.

  11. Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

    Science.gov (United States)

    Zagonel, L. F.; Tizei, L. H. G.; Vitiello, G. Z.; Jacopin, G.; Rigutti, L.; Tchernycheva, M.; Julien, F. H.; Songmuang, R.; Ostasevicius, T.; de la Peña, F.; Ducati, C.; Midgley, P. A.; Kociak, M.

    2016-05-01

    We report on a detailed study of the intensity dependent optical properties of individual GaN/AlN quantum disks (QDisks) embedded into GaN nanowires (NW). The structural and optical properties of the QDisks were probed by high spatial resolution cathodoluminescence (CL) in a scanning transmission electron microscope (STEM). By exciting the QDisks with a nanometric electron beam at currents spanning over three orders of magnitude, strong nonlinearities (energy shifts) in the light emission are observed. In particular, we find that the amount of energy shift depends on the emission rate and on the QDisk morphology (size, position along the NW and shell thickness). For thick QDisks (>4 nm), the QDisk emission energy is observed to blueshift with the increase of the emission intensity. This is interpreted as a consequence of the increase of carriers density excited by the incident electron beam inside the QDisks, which screens the internal electric field and thus reduces the quantum confined Stark effect (QCSE) present in these QDisks. For thinner QDisks (current threshold above which the energy shifts, marking the transition from unscreened to partially screened QCSE. From the threshold value we estimate the lifetime in the unscreened regime. These observations suggest that, counterintuitively, electrons of high energy can behave ultimately as single electron-hole pair generators. In addition, when we increase the current from 1 to 10 pA the light emission efficiency drops by more than one order of magnitude. This reduction of the emission efficiency is a manifestation of the "efficiency droop" as observed in nitride-based 2D light emitting diodes, a phenomenon tentatively attributed to the Auger effect.

  12. Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian-Early Kimmeridgian) inferred from δ18O of Paris Basin oyster shells

    Science.gov (United States)

    Brigaud, Benjamin; Pucéat, Emmanuelle; Pellenard, Pierre; Vincent, Benoît; Joachimski, Michael M.

    2008-08-01

    Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian-Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on non-luminescent parts of shells (n = 264). Intra-shell δ18O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the δ18O values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra-shell variability reflects seasonal variations of temperature and/or salinity. Average amplitudes of about 5 °C in shallow water environments and of about 2-3 °C in deeper offshore environments are calculated. These amplitudes reflect minimum seasonal temperature variation. Our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite δ18O data and are in better agreement with paleontological data. More specifically, a warming trend of about 3 °C is reconstructed for oceanic surface waters during the Early to Middle Oxfordian transition, with maximum temperatures reaching 24 °C in the transversarium Zone (late Middle Oxfordian). From the transversarium Zone to the bimmamatum Zone, a cooling of about 7 °C is indicated, whereas from the bimmamatum Zone, temperatures increased again by about 7 °C to reach 24 °C in average during the cymodoce Zone (Early Kimmeridgian).

  13. Synthesis of zinc oxide microrods and nano-fibers with dominant exciton emission at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Brito, F., E-mail: fro_brito@yahoo.com.m [Laboratorio de Materiales Optoelectronicos del Centro de Ciencias de Sinaloa, Ave. de las Americas 2771 Col. Villa Universidad 80010, Culiacan, Sinaloa (Mexico); Alejo-Armenta, C. [Laboratorio de Materiales Optoelectronicos del Centro de Ciencias de Sinaloa, Ave. de las Americas 2771 Col. Villa Universidad 80010, Culiacan, Sinaloa (Mexico); Garcia-Hipolito, M. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, AP 70-360, Coyoacan 04510, DF (Mexico); Camarillo, E.; Hernandez A, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, Alvaro Obregon 01000, DF (Mexico); Falcony, C. [Departamento de Fisica, CINVESTAV-IPN, AP 14-740, 07000, DF (Mexico); Murrieta S, H. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, Alvaro Obregon 01000, DF (Mexico)

    2011-05-15

    Employing a simple chemical synthesis method, hexagonal-shaped zinc oxide microrods and zinc oxide nano-fibers were deposited on pyrex-glass and aluminum substrates, respectively. Both kinds of deposits showed zincite crystalline phase with lattice parameters: a=3.2498 A and c=5.2066 A. Microrods showed very uniform wide and large sizes of around 1 and 10 {mu}m, respectively. Both deposits were homogeneous over all substrate surfaces. Microrods and nano-fibers resulted with good optical quality and with preferential crystalline growth in [1 0 1 0]and [0 0 0 1]directions. The principal optical characteristics for both microrods and nano-fibers were: a) room-temperature photo and cathodo-luminescent spectra with strong exciton emission centered around 390 nm and with FWHMs around 125 and 160 meV, respectively, b) poor photo and cathode-luminescent emissions in the visible region of the electromagnetic spectrum, c) energy band gap of 3.32 eV, d) good emission efficiency supported by the not-required high energy densities to obtain strong exciton emission and e) good ZnO stoichiometry endorsed by photoluminescent results. These characteristics make of these microrods and nano-fibers good for potential photonic applications. - Research highlights: {yields} Microrods and nano-fibers resulted with good optical quality and with preferential crystalline growth in [1 0 1 0]and [0 0 0 1]directions. {yields} Microrods and nano-fibers resulted with good emission efficiency supported by the not-required high energy densities to obtain strong exciton emission. {yields} The wet chemical method is appropriated for deposition of microrods and nano-fibers with the desired optical properties for its possible application in photonics.

  14. Visualization of trace-element zoning in fluorapatite using BSE and CL imaging, and EPMA and μPIXE/μPIGE mapping

    Science.gov (United States)

    Gros, Katarzyna; Słaby, Ewa; Förster, Hans-Jürgen; Michalak, Przemysław P.; Munnik, Frans; Götze, Jens; Rhede, Dieter

    2016-12-01

    In this paper, zonation patterns of trace elements in fluorapatite are discussed that were visualized using four analytical techniques, namely back-scattered electrons (BSE) and cathodoluminescence (CL) imaging, electron probe micro-analysis (EPMA), and micro-proton-induced X-ray/gamma ray emission (μPIXE/μPIGE) mapping. Each method demonstrates the in-grain compositional variations in a slightly different way. Both BSE and CL provide qualitative data, and the internal textures are displayed in most detail. Additionally, CL points to specific elements enriched in certain growth zones. Qualitative EPMA maps show detailed zonation patterns for specific elements (with high spatial resolution), which are in general correspondence with the patterns observed in BSE and CL images. The μPIXE/μPIGE maps are fully quantitative and the detection limits are relatively low compared to EPMA mapping. In present spot measurements μPIXE demonstrates lower detection limits than EPMA, however, the latter could be considerably improved by extending the acquisition times. There is no significant overlap of REE (rare earth elements) peaks in the acquired μPIXE energy spectra, however, when multiple REEs are present with sufficiently high concentrations, peak deconvolution may pose some difficulties. Spatial resolution of μPIXE/μPIGE images is not sufficiently high to reflect minor textural features, which also result from the greater interaction depth of the proton beam. However, major growth zones are distinguishable. Even though each method has their advantages and limitations, when applied together, they provide an almost complete characterization of compositional variability in trace-element-bearing minerals.

  15. Detrital zircon U-Pb and Hf isotopic data from the Liuling Group in the South Qinling belt: Provenance and tectonic implications

    Science.gov (United States)

    Liao, Xiao-ying; Wang, Ya-wei; Liu, Liang; Wang, Chao; Santosh, M.

    2017-02-01

    The Liuling Group is exposed in the Northern part of the South Qinling orogenic belt. LA-ICP-MS U-Pb analysis of detrital zircons from the meta-sandstones in this Group yields ages ranging between 400 Ma and 3200 Ma, with three prominent age clusters at 500-400 Ma, 850-700 Ma and 1000-900 Ma. A few older zircon populations with U-Pb ages of 1750-1450 Ma, 2000 Ma and 2600-2400 Ma are also present. Age data integrated with cathodoluminescence, trace element data and εHf(t) values of zircon grains show that the Liuling sediments have a complex source. Source rocks mainly include Early Neoproterozoic and Early Paleozoic granitoids, together with minor ultra-high pressure/high pressure (HP-UHP) metamorphic rocks, and paragneiss in the North Qinling belt, and Middle-Late Neoproterozoic magmatic rocks in the South Qinling belt. The dominant population of detrital zircon grains with ages between 500 Ma and 400 Ma show the characteristics of both magmatic and metamorphic zircons. They show three age clusters at 497 Ma, 451 Ma, and ca. 420 Ma and show marked correlation with the three stages of Palaeozoic magmatism, as well as with the peak and retrograde HP-UHP metamorphic stages in the North Qinling belt. This correlation demonstrates that these Early Palaeozoic granitoids and HP-UHP metamorphic rocks in the North Qinling belt were already exhumed to the surface, underwent erosion prior to Middle Devonian time and were then deposited in an extensional basin. Based on the results from detrital zircon U-Pb dating, combined with geochemical data and the regional geology, the deposition of Liuling sediments is inferred to have occurred in a post-orogenic extensional basin, rather than a subduction-related fore-arc basin or a foreland basin formed during or after continental collision.

  16. Ossification Vesicles with Calcium Phosphate in the Eyes of the Insect Copium teucrii (Hemiptera: Tingidae

    Directory of Open Access Journals (Sweden)

    Javier Garcia-Guinea

    2011-01-01

    Full Text Available Arthropod eyes are built of repeating units named ommatidia. Each single ommatidium unit contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The insect Copium eye ommatidia include additional calcium-phosphate deposits, not described in insects to date, which can be examined today using a combined set of modern microscopy and spectroscopy techniques. Teucrium gnaphalodes L'Her plants, growing in central Spain, develop galls induced by Copium insects. A survey of C. teucrii adult specimens resulted in surprising environmental scanning electron microscopy (ESEM images, showing that their bright red eyes contain a calcium-phosphate mineralization. A complete survey of Copium eye specimens was performed by ESEM using energy-dispersive spectroscopy, backscattered electron detector and cathodoluminescence (CL probes, field emission scanning electron microscopy, micro-Raman spectroscopy, and confocal laser scanning microscopy in order to learn ommatidia features, such as chemical composition, molecular structure, cell membrane, and internal ommatidium eye fluids and calcium-phosphate distribution deposits. The CL panchromatic images distinguish between the calcium-phosphate ommatidium and calcium-phosphate setae, which are more apatite rich. They show Raman bands attributable to bone tissue apatite biomaterials, such as bone, collagen, lipids, and blood, i.e., peptides, amide-S, amide-II, amide-III, and cytochrome P-450scc. The chemical composition of both galls and leaves of T. gnaphalodes was determined by gas chromatography – mass spectrometry (GC-MS of their extracts. The spectrometric and microscopic images reveal that the calcium-phosphate mineralization is formed and constrained to Copium ommatidia, which are both matrix vesicles generating mixtures of apatite collagen and operational compound eyes of the insect.

  17. Threading dislocations in GaAs epitaxial layers on various thickness Ge buffers on 300 mm Si substrates

    Science.gov (United States)

    Bogumilowicz, Y.; Hartmann, J. M.; Rochat, N.; Salaun, A.; Martin, M.; Bassani, F.; Baron, T.; David, S.; Bao, X.-Y.; Sanchez, E.

    2016-11-01

    We have grown GaAs epitaxial layers on Ge buffers, themselves on Si (001) substrates, using an Applied Materials 300 mm metal organic chemical vapor deposition tool. We varied the Ge buffer thickness between 0.36 and 1.38 μm and studied the properties of a 0.27 μm thick GaAs layer on top. We found that increasing the Ge buffer thickness yielded smoother GaAs films with an rms surface roughness as low as 0.5 nm obtained on a 5×5 μm2 area. The bow of the substrate increased following a linear law with the epitaxial stack thickness up to 240 μm for a 1.65 μm stack. We have also characterized the threading dislocations present in the GaAs layers using X-ray diffraction and cathodoluminescence. Increasing the Ge buffer thickness resulted in lower threading dislocation densities, enabling us to obtain anti-phase boundary - free GaAs films with a threading dislocation density as low as 3×107 cm-2. In addition, atomic force microscopy surface topology measurements showed the presence of pits in the GaAs layers whose density agreed well with other threading dislocation density assessments. It thus seems that threading dislocations can in certain cases induce some growth rate variations, making them visible in as-grown GaAs films. Using thicker Ge buffers results in smoother films with less threading dislocations, with the side effect of increasing the bow on the wafer. If bow is not an issue, this is a practical approach to improve the GaAs (on Ge buffer) on silicon quality.

  18. {sup 14}C chronology of the oldest Scandinavian church in use. An AMS/PIXE study of lime lump carbonate in the mortar

    Energy Technology Data Exchange (ETDEWEB)

    Lindroos, Alf, E-mail: alf.lindroos@abo.fi [Geology and Mineralogy, Department of Natural Sciences, Åbo Akademi University (Finland); Art History, Faculty of Art, Åbo Akademi University (Finland); Ranta, Heikki [Diocese of Lund, Church of Sweden (Sweden); Heinemeier, Jan [AMS " 1" 4C Dating Laboratory, Department of Physics and Astronomy, University of Aarhus (Denmark); Lill, Jan-Olof [Accelerator Laboratory, Turku PET Centre, Åbo Akademi University (Finland)

    2014-07-15

    Mortar dating was applied to newly revealed, original mortar in the church of Dalby in Scania, southern Sweden which is considered to be the oldest still standing church in Scandinavia. Small white lime lumps were sampled by chipping from the supporting pillars in the interior of the church. Special emphasis was in sampling lime lumps because the church is situated in the Scania limestone area and aggregate limestone contamination was anticipated in the bulk mortars. Earlier studies have, however, shown that lime lumps do not contain aggregate material but only possible limestone rests from incomplete calcination. The sampled material was prepared for radiocarbon AMS dating. The carbonate in the lime lumps was hydrolyzed according to the sequential leaching technique developed for the Århus {sup 14}C laboratory in Denmark. Prior to the hydrolysis the lime lumps were examined for dead-carbon contamination using a stereo microscope and cathodoluminescence. The lime lumps displayed heterogeneous carbonate luminescence. This is, however, common and it was not considered a problem because carbonate growth in changing pH/Eh conditions often leads to changing luminescence colors. Two lumps had little dead carbon contamination and an early second millennium {sup 14}C signature. One lump, however, seemed to be heavily contaminated with dead carbon. Since the sample passed the microscopic screening, the leftovers of the lump was subjected to PIXE analysis and compared with the other two lumps. The well-defined, early 2nd millennium {sup 14}C age of the lime lumps of this particular church is an important contribution to the discussion on stone church chronology in Scandinavia.

  19. First description of Phanerozoic radiaxial fibrous dolomite

    Science.gov (United States)

    Richter, D. K.; Heinrich, F.; Geske, A.; Neuser, R. D.; Gies, H.; Immenhauser, A.

    2014-05-01

    The petrographic analysis and crystallographic analysis of concretionary carbonate cements ("coal balls") from Carboniferous paralic swamp deposits reveal the presence of (length fast) radiaxial fibrous dolomite (RFD), a fabric not previously reported from the Phanerozoic. This finding is of significance as earlier reports of Phanerozoic radiaxial fibrous carbonates are exclusively of calcite mineralogy. Dolomite concretions described here formed beneath marine transgressive intervals within palustrine coal seams. This is of significance as seawater was arguably the main source of Mg2 + ions for dolomite formation. Here, data from optical microscopy, cathodoluminescence, electron backscattered diffraction, X-ray diffraction and geochemical analyses are presented to characterize three paragenetic dolomite phases and one calcite phase in these concretions. The main focus is on the earliest diagenetic, non-stoichiometric (degree of order: 0.41-0.46) phase I, characterized by botryoidal dolomite constructed of fibres up to 110 μm wide with a systematic undulatory extinction and converging crystal axes. Petrographic and crystallographic evidence clearly qualifies phase I dolomite as radiaxial fibrous. Conversely, fascicular optical fabrics were not found. Carbon-isotope ratios (δ13C) are depleted (between - 11.8 and - 22.1‰) as expected for carbonate precipitation from marine pore-fluids in organic-matter-rich, paralic sediment. Oxygen isotope (δ18O) ratios range between - 1.3 and - 6.0‰. The earliest diagenetic nature of these cements is documented by the presence of ubiquitous, non-compacted fossil plant remains encased in phase I dolomite as well as by the complex zoned luminescence patterns in the crystals and is supported by crystallographic and thermodynamic considerations. It is argued that organic matter, and specifically carboxyl groups, reduced thermodynamic barriers for dolomite formation and facilitated Mg/CaCO3 precipitation. The data shown here

  20. Tunable-color luminescence via energy transfer in NaCa13/18Mg5/18PO4:A (A = Eu2+/Tb3+/Mn2+, Dy3+) phosphors for solid state lighting.

    Science.gov (United States)

    Li, Kai; Fan, Jian; Mi, Xiaoyun; Zhang, Yang; Lian, Hongzhou; Shang, Mengmeng; Lin, Jun

    2014-11-17

    A series of NaCa13/18Mg5/18PO4(NCMPO):A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) phosphors have been prepared by the high-temperature solid-state reaction method. The X-ray diffraction (XRD) and Rietveld refinement, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), cathodoluminescence (CL), decay lifetimes, and PL quantum yields (QYs) were utilized to characterize the phosphors. The pure crystalline phase of as-prepared samples has been demonstrated via XRD measurement and Rietveld refinements. XPS reveals that the Eu(2+)/Tb(3+)/Mn(2+) can be efficiently doped into the crystal lattice. NCMPO:Eu(2+)/Tb(3+)/Mn(2+) phosphors can be effectively excited under UV radiation, which show tunable color from purple-blue to red including white emission based on energy transfer from Eu(2+) to Tb(3+)/Mn(2+) ions. Under low-voltage electron beam bombardment, the NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) display their, respectively, characteristic emissions with different colors, and the CL spectrum of NCMPO:0.04Tb(3+) has the comparable intensity to the ZnO:Zn commercial product. In addition, the calculated CIE coordinate of NCMPO:0.04Tb(3+) (0.252, 0.432) is more saturated than it (0.195, 0.417). These results reveal that NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) may be potential candidate phosphors for WLEDs and FEDs.

  1. MO-G-BRF-07: Optical Characterization of Novel Terbium-Doped Nanophosphors Excited by Clinical Electron and Photon Beams for Potential Use in Molecular Imaging Or Photodynamic Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Darafsheh, A; Paik, T; Tenuto, M; Najmr, S; Friedberg, J; Murray, C; Finlay, J [University of Pennsylvania, Philadelphia, PA (United States)

    2014-06-15

    Purpose: Optical properties of terbium (Tb3+)-doped gadolinium trifluoride (GdF3) nanoplates irradiated by electron and photon beams were investigated for their potential as optical probes. The contribution of induced Cerenkov radiation in exciting the nanophosphors was investigated as well. Methods: The emission spectra of Terbium-doped GdF3 dispersed in hexane, embedded in tissue mimicking phantoms were collected by an optical fiber connected to a CCD-coupled spectrograph, while the samples were irradiated by a medical linear accelerator with electron beams of energies 6, 9, 12, 16, and 20 MeV or X-ray beams of energies of 6, and 15 MV. The contribution of induced Cerenkov radiation in exciting the nanophosphores was investigated in a dedicated experimental apparatus through optical isolation of the samples and also by using 125 kVp X-ray beams whose energy is below the threshold for generating Cerenkov radiation in that medium. Results: Terbium-doped GdF3 nanoplates show characteristic cathodoluminescence emission peaks at 488, 543, 586, and 619 nm, which are responsible for the characteristic f-f transition of terbium ion. In a series of experiments, the contribution of Cerenkov radiation in the luminescence of such nanophosphors was ruled out. Conclusion: We have characterized the optical properties of Terbium-doped GdF3 nanoplates. Such nanocrystals with emission tunability and high surface area that facilitates attachment with targeting reagents are promising in situ light source candidates for molecular imaging or exciting a photosensitizer for ultralow fluence photodynamic therapy. This work is supported by the Department of Radiation Oncology at the University of Pennsylvania, the American Cancer Society through IRG-78-002-28, and the University of Pennsylvania's Nano/Bio Interface Center through NSEC DMR08-32802.

  2. Diagenesis of the Lisburne Group, northeastern Brooks Range, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, R.C.; Goldstein, R.H.; Enos, P. [and others

    1995-05-01

    Petrographic cathodoluminescence studies of the cement stratigraphy of the Lisburne Group yield insights on its diagenetic history. Crosscutting relationships between features of subaerial exposure and calcite cements show that early generations of nonferroan, nonluminescent and multibanded-luminescent calcites are synchronous with or postdated by subaerial exposure surfaces within the Lisburne. Surfaces of subaerial exposure occur at 18 horizons within the Lisburne and are distinguished by features as laminated crusts, rhizoliths, autoclastic breccia, fissure fills, mud cracks, and erosional surfaces. Crosscutting relationships also occur between calcite cements and clasts in karst breccias and conglomerates that formed along the sub-Permian unconformity at the top of the Lisburne. The sub-Permian unconformity postdates later generations of calcite cement. These cements formed in the following sequence: nonferroan to low-ferroan, dully luminescent calcite; ferroan, very-dully luminescent calcite; and second generation of nonferroan, multibanded calcite. The crosscutting relationships not only constrain the timing of cement precipitation, but also suggest that the cements probably were precipitated from meteoric groundwaters introduced during subaerial exposure of the Lisburne platform. Late cements in the Lisburne postdate the Permian Echooka Formation. These cements are low-ferroan, moderately-bright to dully luminescent calcite, followed by a second generation of ferroan, very-dully luminescent calcite. Features of compaction and pressure solution are coincident with the precipitation of the late ferroan calcite and further constrain its timing to deep burial of the Lisburne. The youngest phase of calcite cement precipitated in the Lisburne Group is nonferroan, very-dully luminescent calcite. It commonly fills tectonically-induced shear fractures, indicating precipitation after the onset of Cretaceous (and/or Cenozoic) tectonism in the northeastern Brooks Range.

  3. Evidence of subduction and crust-mantle mixing from a single diamond

    Science.gov (United States)

    Schulze, Daniel J.; Harte, Ben; Valley, John W.; Channer, Dominic M. DeR.

    2004-09-01

    Cathodoluminescence (CL) imaging of polished sections of a diamond from the Guaniamo region of Venezuela suggests a history of the diamond involving two periods of growth separated by a period of resorption and possibly brittle deformation. In situ electron probe analysis of multiple eclogitic garnet inclusions reveals a correlation between garnet composition and location in the stone. An early-formed garnet in the diamond core has higher Ca/(Ca+Mg) and lower Mg/(Mg+Fe) values than later garnets associated with the second period of diamond growth. This variation conforms to an extensive trend of variation in the suite of eclogitic garnets extracted from Venezuelan diamonds. The diamond is zoned in carbon isotope composition (in situ secondary ion mass spectrometry, SIMS, data). The core compositions ( δ13C PDB), corresponding to the first stage of growth, average -17.7‰. The second period of growth is apparently in two sub-sets of CL zones with mean values of -13.0‰ and -7.9‰. Nitrogen contents of diamond are low (30-300 atomic ppm) and do not correlate with carbon isotope composition. Oxygen isotope ratios of the garnet inclusions are elevated substantially above those expected for "common mantle"; δ18O VSMOW of early garnet is approximately +10.5‰ and two late garnets average +8.8‰. The evolutionary trend of magnesium enrichment in garnet is unlikely to represent igneous fractionation. The stable isotope data are consistent with diamond formation in subducted meta-basic rocks that had interacted with sea water at low temperatures at or near the sea floor and contained a substantial biogenic carbon component. During or following subduction, diamonds continued to form in an evolving system that was progressively modified by interaction with mantle material.

  4. Recycling of Proterozoic crust in Pleistocene juvenile magma and rapid formation of the Ok Tedi porphyry Cu-Au deposit, Papua New Guinea

    Science.gov (United States)

    van Dongen, M.; Weinberg, R. F.; Tomkins, A. G.; Armstrong, R. A.; Woodhead, J. D.

    2010-02-01

    We present an investigation of the combined U-Pb, O and Hf isotope composition of zircons from a giant porphyry copper-gold deposit, hosted in a shoshonitic intermediate intrusive complex of the Ok Tedi area in Papua New Guinea. This area is part of a Late Miocene-Pliocene collisional fold-and-thrust belt related to island arc accretion to the Australian plate. Cathodoluminescence and transmitted light imaging reveal distinct zircon textures such as spongy rims and inherited zircon cores. Spongy textures, interpreted to result from corrosion of the surface by hydrothermal fluids, do not seem to affect the U-Pb, O and Hf isotope composition. Calculated SHRIMP U-Pb ages for the rims are 1.1-1.4 Ma whereas the inherited component is ~ 1.8 Ga. Our age results combined with existing K-Ar results, constrain the formation of the Ok Tedi deposit to Oxygen isotope composition (δ 18O), measured by SHRIMP, is ~ 6.5‰ for Pleistocene zircons but extend to values of ~ 8.3‰ or more for Proterozoic zircon cores. Likewise, corrected Hf isotope ratios from LA-ICP-MS analyses are centred on 0.2825 ( ɛHf(t) = - 6.5 ± 2) for Pleistocene zircons, compared to ~ 0.2815 ( ɛHf(t) = + 5 to - 3) for Proterozoic components. The Pleistocene zircon isotope signature is best explained by assimilation of Proterozoic crustal source material into asthenospheric mantle-derived magma similar to that of the Pliocene Porgera Au-only deposit in the same orogen.

  5. Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al.

    Science.gov (United States)

    Estrin, Y; Rich, D H; Rozenfeld, N; Arad-Vosk, N; Ron, A; Sa'ar, A

    2015-10-30

    The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ∼2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ω(sp), and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals.

  6. The central tower of the cathedral of Schleswig - New investigations to understand the alcali-silica reaction of historical mortars

    Science.gov (United States)

    Wedekind, Wanja; Protz, Andreas

    2016-04-01

    The damaging alcali-silica reaction leads to crack-formation and structural destruction at noumerous, constructed with cement mortar, buildings worldwide. The ASR-reaction causes the expansion of altered aggregates by the formation of a swelling gel. This gel consists of calcium silicate hydrate (C-S-H) that increases in volume with water, which exerts an expansive pressure inside the material. The cathedral of Schleswig is one of the oldest in northern Germany. The first church was built in 985-965. The Romanesque building part was erected around 1180 and the Gothic nave at the end of the 13th century. The central tower was constructed between 1888 and 1894 with brick and cement mortar. With 112 meters, the tower is the second-largest church spire of the country of Schleswig-Holstein in northern Germany. Due to the formation of cracks and damages from 1953 to 1956 first restoration works took place. Further developments of cracks are making restoration necessary again today. For developing a suitable conservation strategy, different investigations were done. The investigation included the determination of the pore space properties, the hygric and thermal dilatation and mercury porosimetry measurements. Furthermore, the application of cathodoluminescence microscopy may give information about the alteration process and microstructures present and reveal the differences between unaltered and altered mortars. An obvious relation between the porosity and the swelling intensity could be detected. Furthermore it becomes apparent, that a clear zonation of the mortar took place. The mortar near the surface is denser with a lower porosity and has a significantly lower swelling or dilatation.

  7. Luminescence characterization of dental ceramics for individual retrospective dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Correcher, V.; Gomesdarocha, R. [CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Garcia G, J. [Consejo Superior de Investigaciones Cientificas, Museo Nacional de Ciencias Naturales, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Rivera M, T., E-mail: v.correcher@ciemat.es [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    Full text: Ceramic materials in general and dental crowns in particular exhibit thermoluminescence (Tl) properties and are of interest in the field of individual retrospective dosimetry. This property could be potentially employed to provide a means of determining cumulative exposure to external gamma radiation arising from accidents or large-scale incidents (radiological terrorism) involving population groups where conventional monitoring has not been established. The thermal stability and dose effect of the UV-blue Tl emission of a well characterized Spanish samples (by means of cathodoluminescence and electron-probe microanalysis) are here reported. It displays (i) an excellent linearity in the range of 0.12 - 9.6 Gy, (II) good stability of the Tl signal of 0.6, 1.2 and 2.4 Gy irradiated samples after 6 months of storage showing an initial rapid decay (ca. 30%) maintaining the stability from 30 days onwards. It means that the electron population decreases asymptotically by the X - axis and the involved electrons are located in deeper traps at room temperature. (III) The reusability performed on the dental ceramic, involving successive cycles of irradiation (1.2 Gy) followed by readout (up to 500 degrees C), exhibited a negligible variation in the Tl response, when measured six times. (IV) The tests of thermal stability at different temperatures (in the range of 100-240 degrees C) confirms a continuum in the trap distribution with progressive changes in the glow curve shape, intensity and temperature position of the maximum peak. Therefore, these preliminary results suggest that dental ceramics could be used as suitable dosimeters in retrospective conditions. (Author)

  8. Criteria for recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic, fluid inclusion, and isotopic analysis of the Tera Group, Northern Spain

    Science.gov (United States)

    González-Acebrón, Laura; Goldstein, R. H.; Mas, Ramón; Arribas, José

    2011-11-01

    Stratigraphic relations, detailed petrography, microthermometry of fluid inclusions, and fine-scale isotopic analysis of diagenetic phases indicate a complex thermal history in Tithonian fluvial sandstones and lacustrine limestones of the Tera Group (North Spain). Two different thermal events have been recognized and characterized, which are likely associated with hydrothermal events that affected the Cameros Basin during the mid-Cretaceous and the Eocene. Multiple stages of quartz cementation were identified using scanning electron microscope cathodoluminescence on sandstones and fracture fills. Primary fluid inclusions reveal homogenization temperatures (Th) from 195 to 350°C in the quartz cements of extensional fracture fillings. The high variability of Th data in each particular fluid inclusion assemblage is related to natural reequilibration of the fluid inclusions, probably due to Cretaceous hydrothermal metamorphism. Some secondary fluid inclusion assemblages show very consistent data (Th = 281-305°C) and are considered not to have reequilibrated. They are likely related to an Eocene hydrothermal event or to a retrograde stage of the Cretaceous hydrothermalism. This approach shows how multiple thermal events can be discriminated. A very steep thermal gradient of 97-214°C/km can be deduced from δ18O values of ferroan calcites (δ18O -14.2/-11.8‰ V-PDB) that postdate quartz cements in fracture fillings. Furthermore, illite crystallinity data (anchizone-epizone boundary) are out of equilibrium with high fluid inclusion Th. These observations are consistent with heat-flux related to short-lived events of hydrothermal alteration focused by permeability contrasts, rather than to regional heat-flux associated with dynamo-thermal metamorphism. These results illustrate how thermal data from fracture systems can yield thermal histories markedly different from host-rock values, a finding indicative of hydrothermal fluid flow.

  9. Growth of high Mg content wurtzite MgZnO epitaxial films via pulsed metal organic chemical vapor deposition

    Science.gov (United States)

    Alema, Fikadu; Ledyaev, Oleg; Miller, Ross; Beletsky, Valeria; Osinsky, Andrei; Schoenfeld, Winston V.

    2016-02-01

    We report on the growth of high Mg content, high quality, wurtzite MgxZn1-xO (MgZnO) epitaxial films using a pulsed metal organic chemical vapor deposition (PMOCVD) method. Series of MgZnO films with variable Mg concentration were deposited on bare and AlN coated sapphire substrates. The band gap of the films estimated using UV-visible transmission spectra ranges from 3.24 eV to 4.49 eV, corresponding to fraction of Mg between x=0.0 and x=0.51, as determined by Rutherford backscattering spectroscopy. The cathodoluminescence (CL) measurement has shown a blue-shift in the peak position of MgZnO with an increasing Mg content. No multi-absorption edges and CL band splitting were observed, suggesting the absence of phase segregation in the as grown films. The crystal structure and phase purity of the films were also confirmed by XRD analysis. Hall effect measurement in van der Pauw configuration was employed to evaluate the electrical properties of the films. With a rise in Mg incorporation into the ZnO lattice, the films became very resistive, consistent with the widening of the band gap. The AFM measurement on the films has shown a decreasing surface roughness with an Mg content. To the best of our knowledge, the current result shows the highest Mg content (x=0.51), high quality, wurtzite MgZnO epitaxial film ever grown by MOCVD. The high Mg incorporation without phase separation is believed to be due to the non-equilibrium behavior of the PMOCVD in which the kinetic processes dominate the thermodynamic one.

  10. Low dislocation density InAlN/AlN/GaN heterostructures grown on GaN substrates and the effects on gate leakage characteristics

    Science.gov (United States)

    Kotani, Junji; Yamada, Atsushi; Ishiguro, Tetsuro; Tomabechi, Shuichi; Nakamura, Norikazu

    2016-04-01

    This paper reports on the electrical characterization of Ni/Au Schottky diodes fabricated on InAlN high-electron-mobility transistor (HEMT) structures grown on low dislocation density free-standing GaN substrates. InAlN HEMT structures were grown on sapphire and GaN substrates by metal-organic vapor phase epitaxy, and the effects of threading dislocation density on the leakage characteristics of Ni/Au Schottky diodes were investigated. Threading dislocation densities were determined to be 1.8 × 104 cm-2 and 1.2 × 109 cm-2 by the cathodoluminescence measurement for the HEMT structures grown on GaN and sapphire substrates, respectively. Leakage characteristics of Ni/Au Schottky diodes were compared between the two samples, and a reduction of the leakage current of about three to four orders of magnitude was observed in the forward bias region. For the high reverse bias region, however, no significant improvement was confirmed. We believe that the leakage current in the low bias region is governed by a dislocation-related Frenkel-Poole emission, and the leakage current in the high reverse bias region originates from field emission due to the large internal electric field in the InAlN barrier layer. Our results demonstrated that the reduction of dislocation density is effective in reducing leakage current in the low bias region. At the same time, it was also revealed that another approach will be needed, for instance, band modulation by impurity doping and insertion of insulating layers beneath the gate electrodes for a substantial reduction of the gate leakage current.

  11. Contrasting hydrological processes of meteoric water incursion during magmatic-hydrothermal ore deposition: An oxygen isotope study by ion microprobe

    Science.gov (United States)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Bouvier, Anne-Sophie; Baumgartner, Lukas; Heinrich, Christoph A.

    2016-10-01

    Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic-hydrothermal systems has been linked to tin ore deposition in granitic plutons. In contrast, evidence from porphyry copper ore deposits suggests that crystallizing subvolcanic magma bodies are only affected by meteoric water incursion in peripheral zones and during late post-ore stages. We apply high-resolution secondary ion mass spectrometry (SIMS) to analyze oxygen isotope ratios of individual growth zones in vein quartz crystals, imaged by cathodo-luminescence microscopy (SEM-CL). Existing microthermometric information from fluid inclusions enables calculation of the oxygen isotope composition of the fluid from which the quartz precipitated, constraining the relative timing of meteoric water input into these two different settings. Our results confirm that incursion of meteoric water directly contributes to cooling of shallow granitic plutons and plays a key role in concurrent tin mineralization. By contrast, data from two porphyry copper deposits suggest that downward circulating meteoric water is counteracted by up-flowing hot magmatic fluids. Our data show that porphyry copper ore deposition occurs close to a magmatic-meteoric water interface, rather than in a purely magmatic fluid plume, confirming recent hydrological modeling. On a larger scale, the expulsion of magmatic fluids against the meteoric water interface can shield plutons from rapid convective cooling, which may aid the build-up of large magma chambers required for porphyry copper ore formation.

  12. Optical properties of Yb ions in GaN epilayer

    Science.gov (United States)

    Jadwisienczak, W. M.; Lozykowski, H. J.

    2003-07-01

    In recent years, an important effort in semiconductor materials research has been devoted to III-nitrides semiconductors doped with rare earth ions due to the high potential of these materials in light-emitting device applications. Ytterbium (Yb 3+) is one of a few lanthanide ions which have not been investigated as an optically active center in these materials yet. In this paper we report the observation of luminescence from GaN films grown on sapphire (0 0 0 1) substrate by metal organic chemical vapor deposition and doped by implantation with Yb 3+ ions. The high resolution photo- and cathodoluminescence spectra of GaN:Yb 3+ were studied at different excitation conditions in temperatures ranging from 8 to 330 K and revealed weak thermal quenching. The luminescence emission lines are assigned to transitions between the spin-orbit levels 2F 5/2 → 2F 7/2 of Yb 3+ (4f 13). The analysis of the Yb luminescence spectra allowed us to suggest the energy level diagram of the crystal-field-split 4f 13 levels for the Yb ion center. The most probable lattice location of Yb in GaN is the substitutional Ga site. Furthermore, the luminescence kinetics of internal transitions of Yb 3+ incorporated in GaN was investigated by means of decay and time-resolved luminescence measurements. It was found that the ytterbium decay is non-exponential with dominant exponential term of ˜100 μs with little dependence on the ambient temperature. The results indicate that Yb-doped GaN epilayer may be suitable as a material for near infrared optoelectronic devices.

  13. Sm-Nd and zircon SHRIMP U-Pb dating of Huilanshan mafic granulite in the Dabie Mountains and its zircon trace element geochemistry

    Institute of Scientific and Technical Information of China (English)

    HOU; Zhenhui; LI; Shuguang; CHEN; Nengsong; LI; Qiuli; LIU

    2005-01-01

    The mafic granulites from Huilanshan are outcropped on the center of the Luotian dome in the northern Dabie Mountains. The Sm-Nd isochron defined by granulite-facies metamorphic minerals (garnet + clinopyroxene + hypersthene) yields an age of 136(±)18 Ma indicating the early Cretaceous granulite-facies metamorphism. The cathodoluminescence (CL) images of zircons from the granulite show clearly core-mantle-rim structures. The zircon cores are characterized by typical oscillatory zoning and highly HREE enriched patterns, which suggests their magma origin. Some zircon cores among them with little Pb loss give SHRIMP U-Pb ages ranging from 753 to 780 Ma, which suggests that the protolith of Huilanshan granulite is Neoproterozoic mafic rocks. The zircon mantles usually cut across the oscillatory zone of the zircon cores have 3―10 times lower REE, Th, U, Y, Nb and Ta contents than the igneous zircon cores but have high common Pb contents. These characteristics suggest that they were formed by hydrothermal alteration of the igneous zircons. The part of zircon mantles with little Pb loss give a similar SHRIMP U-Pb age (716―780 Ma) to the igneous zircon cores, which implies that the hydrothermal events occurred closely to the magmatic emplacement. In view of the strong early Cretaceous magmatism in the Luotian dome, consequently, the Huilanshan mafic granulite was formed by heating of the Neoproterozoic mafic rocks in mid-low crust, which caused the granulite-facies metamorphism underneath the Dabie Mountains. The similarity between the granulite metamorphic age (136±18 Ma) defined by Sm-Nd isochron and K-Ar age of 123―127 Ma given by amphible from the gneiss in Luotian dome suggests a rapid uplifting of the Luotian dome, which may result in further exhumation of the ultrahigh pressure metamorphic rocks in the Dabie Mountains.

  14. Green light emission in aluminum oxide powders doped with different terbium concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Mariscal B, L; Falcony, C. [IPN, Centro de Investigacion y de Estudios Avanzados, 07360 Ciudad de Mexico (Mexico); Carmona T, S.; Murrieta, H.; Sanchez A, M. A. [UNAM, Instituto de Fisica, 04510 Ciudad de Mexico (Mexico); Vazquez A, R. [IPN, Escuela Superior de Computo, 07738 Ciudad de Mexico (Mexico); Garcia R, C. M., E-mail: mariscal2005@gmail.com [UNAM, Facultad de Ciencias, 04510 Ciudad de Mexico (Mexico)

    2016-11-01

    Different emission intensities presented in aluminum oxide phosphors corresponding to different concentrations of doping performed with terbium are analyzed. The phosphors were synthesized by the evaporation technique and were characterized by photo and cathodoluminescence, X-ray diffraction and EDS techniques for different incorporation percentages of terbium as dopant; they show characteristic transitions in 494, 543, 587 and 622 nm, corresponding to {sup 5}D{sub 4} → {sup 7}F{sub 6}, {sup 5}D{sub 4} → {sup 7}F{sub 5}, {sup 5}D{sub 4} → {sup 7}F{sub 4} and {sup 5}D{sub 4} → {sup 7}F{sub 3}, respectively when they are excited with λ{sub exc} = 380 nm wavelength at room temperature. The results of X-ray diffraction show the presence of α-Al{sub 2}O{sub 3} phases with peaks located at 2θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, and the δ-Al{sub 2}O-3 phase 2θ = 32.82, 45.8, 61.36 and 66.74. These compounds were heat treated for two hours at 1100 degrees Celsius. EDS analyzes indicate that these compounds have close to 60% oxygen around of 40% aluminum in the presence of terbium as dopant which indicates a stoichiometry close to the expected one for alumina. (Author)

  15. Miocene-Pleistocene Paleoclimate and Paleoenvironment in the Meade Basin, Kansas

    Science.gov (United States)

    Snell, K. E.; Uno, K. T.; Fetrow, A. C.; Burgess, C.; Lukens, W. E.; Fox, D. L.; Fox-Dobbs, K.; Polissar, P. J.

    2015-12-01

    The Meade Basin in southwestern Kansas preserves a unique record of paleovegetation and small mammal faunal change from the Miocene to the Pleistocene. Many of the paleosols preserved in this basin contain paleosol carbonate nodules, thick calcretes and abundant organic-rich horizons, which makes it ideally suited for a multiproxy study that explores the role of paleoenvironmental change in driving floral and faunal change. Here we focus on the carbonate samples where we measured carbon and oxygen isotopes (δ13Cc and δ18Oc, respectively); used clumped isotope thermometry (Δ47) to estimate soil temperature and soil water δ18O; and assessed the preservation state and additional paleoenvironmental features of the samples using optical and cathodoluminescence (CL) microscopy. The carbon isotope record matches previous studies from the region and shows an increase in the relative abundance of C4 biomass on the landscape since the late Miocene. The Δ47 temperatures and the δ18O of soil water, while variable, show no significant change in average values through time. The textural and luminescenece characteristics suggest some samples have undergone moderate to extensive diagenetic alteration from groundwater fluids, perhaps causing some of the variability in the geochemical records. Soil depth may also account for some of the variability. Overall, these data suggest that temperature is unlikely to be the dominant factor driving paleovegetation and faunal change in this region from the Miocene to Pleistocene. In addition, these data highlight the importance of assessing preservation for all carbonate samples, regardless of whether or not the samples have been deeply buried.

  16. Growth and luminescent properties of single crystalline films of Ce3+ doped Pr1-xLuxAlO3 and Gd1-xLuxAlO3 perovskites

    Science.gov (United States)

    Zorenko, Yu; Gorbenko, V.; Zorenko, T.; Voznyak, T.; Riva, F.; Douissard, P. A.; Martin, T.; Fedorov, A.; Suchocki, A.; Zhydachevskii, Ya.

    2017-01-01

    The paper is dedicated to development of UV emitting scintillating screens for microimaging applications based on the single crystalline films (SCFs) of Ce doped Gd1-xLuxAlO3 and Pr1-xLuxAlO3 (x=0-1) multicomponent perovskites grown onto YAlO3 (YAP) substrates using the liquid phase epitaxy (LPE) method with the objective to improve the X-ray stopping power. Recently Riva et al. [1] have reported that the full set of GdxLu1-xAlO3 SCFs with x values in x=0-1.0 range can be crystallized on YAP substrates using this technique. We report here that PrxLu1-xAlO3 SCFs with x values in x=0-0.5 range can be grown also by the LPE method from PbO-B2O3 flux onto the same YAP substrates. The structural quality of the films was studied using X-ray diffraction. The optical properties of Ce3+ doped of Gd1-xLuxAlO3 and Pr1-xLuxAlO3 (x=0-1) multicomponent perovskite films, studied by traditional spectroscopic methods, such as absorption, cathodoluminescence, photoluminescence and light yield measurements under α-particles excitation, are also reported in this work. We have shown that Pb2+ flux related impurity has significantly larger influence on the light yield of Pr0.5Lu0.5AlO3:Ce, GdAlO3:Ce and Gd0.5Lu0.5AlO3:Ce SCFs in comparison with the YAP:Ce and LuAlO3:Ce counterparts grown onto YAP substrates.

  17. Luminescence and micro-Raman investigations on inclusions of unusual habit in chrysoprase from Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Ayvac Latin-Small-Letter-Dotless-I kl Latin-Small-Letter-Dotless-I , M., E-mail: mayvacikli@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey); Garcia-Guinea, J.; Jorge, A. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Akal Latin-Small-Letter-Dotless-I n, I.; Kotan, Z. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, 45010 Muradiye-Manisa (Turkey)

    2012-07-15

    Chemical analyses performed on chrysoprase from Turkey have shown many trace elements as well as rare earth impurities. Quantitative chemical analyses of inclusions in minerals can improve our understanding of the chemistry of surface. The environmental scanning electron microscope (ESEM) with an attached X-ray energy dispersive system (EDS) is capable of producing rapid and accurate major element chemical analyses of individual inclusions in crystals larger than about 30 {mu}m in diameter. The samples were examined with lifetime-resolved and spatially-resolved cathodoluminescence (CL), and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Spatially resolved CL results at room temperature were recorded for two different areas. Bulk area displays with low CL emission and pores contain iron phases such as chromite, hematite and anatase which cause the green color. For the raw data in the lifetime resolved CL spectrum, at least three broad emission bands were detected in a yellow band of the highest intensity at about 550 nm, a weaker orange band at about 650 nm, and a red band at 720 nm. It is assumed that there are links between the CL emissions and the presence of some transition metal and REE elements, but it is obvious that all trace elements do not play a direct role. Micro-Raman measurements were performed on chrysoprase and these showed a characteristic intensive Raman band peaked at 464 cm{sup -1} which can be inferred to {nu}{sub 2} doubly symmetric bending mode of [SiO{sub 4}/M] centers. Raman spectrum of all inclusions found in the material are also given and discussed in detail. - Highlights: Black-Right-Pointing-Pointer Luminescence and Raman investigations of Chrysoprase. Black-Right-Pointing-Pointer Characteristic intensive Raman band peaked at 464 cm{sup -1}. Black-Right-Pointing-Pointer Ironed phases such as chromite, hematite and anatase.

  18. A Rare Glimpse of Paleoarchean Life: Geobiology of an Exceptionally Preserved Microbial Mat Facies from the 3.4 Ga Strelley Pool Formation, Western Australia.

    Science.gov (United States)

    Duda, Jan-Peter; Van Kranendonk, Martin J; Thiel, Volker; Ionescu, Danny; Strauss, Harald; Schäfer, Nadine; Reitner, Joachim

    2016-01-01

    Paleoarchean rocks from the Pilbara Craton of Western Australia provide a variety of clues to the existence of early life on Earth, such as stromatolites, putative microfossils and geochemical signatures of microbial activity. However, some of these features have also been explained by non-biological processes. Further lines of evidence are therefore required to convincingly argue for the presence of microbial life. Here we describe a new type of microbial mat facies from the 3.4 Ga Strelley Pool Formation, which directly overlies well known stromatolitic carbonates from the same formation. This microbial mat facies consists of laminated, very fine-grained black cherts with discontinuous white quartz layers and lenses, and contains small domical stromatolites and wind-blown crescentic ripples. Light- and cathodoluminescence microscopy, Raman spectroscopy, and time of flight-secondary ion mass spectrometry (ToF-SIMS) reveal a spatial association of carbonates, organic material, and highly abundant framboidal pyrite within the black cherts. Nano secondary ion mass spectrometry (NanoSIMS) confirmed the presence of distinct spheroidal carbonate bodies up to several tens of μm that are surrounded by organic material and pyrite. These aggregates are interpreted as biogenic. Comparison with Phanerozoic analogues indicates that the facies represents microbial mats formed in a shallow marine environment. Carbonate precipitation and silicification by hydrothermal fluids occurred during sedimentation and earliest diagenesis. The deciphered environment, as well as the δ13C signature of bulk organic matter (-35.3‰), are in accord with the presence of photoautotrophs. At the same time, highly abundant framboidal pyrite exhibits a sulfur isotopic signature (δ34S = +3.05‰; Δ33S = 0.268‰; and Δ36S = -0.282‰) that is consistent with microbial sulfate reduction. Taken together, our results strongly support a microbial mat origin of the black chert facies, thus providing

  19. A Rare Glimpse of Paleoarchean Life: Geobiology of an Exceptionally Preserved Microbial Mat Facies from the 3.4 Ga Strelley Pool Formation, Western Australia.

    Directory of Open Access Journals (Sweden)

    Jan-Peter Duda

    Full Text Available Paleoarchean rocks from the Pilbara Craton of Western Australia provide a variety of clues to the existence of early life on Earth, such as stromatolites, putative microfossils and geochemical signatures of microbial activity. However, some of these features have also been explained by non-biological processes. Further lines of evidence are therefore required to convincingly argue for the presence of microbial life. Here we describe a new type of microbial mat facies from the 3.4 Ga Strelley Pool Formation, which directly overlies well known stromatolitic carbonates from the same formation. This microbial mat facies consists of laminated, very fine-grained black cherts with discontinuous white quartz layers and lenses, and contains small domical stromatolites and wind-blown crescentic ripples. Light- and cathodoluminescence microscopy, Raman spectroscopy, and time of flight-secondary ion mass spectrometry (ToF-SIMS reveal a spatial association of carbonates, organic material, and highly abundant framboidal pyrite within the black cherts. Nano secondary ion mass spectrometry (NanoSIMS confirmed the presence of distinct spheroidal carbonate bodies up to several tens of μm that are surrounded by organic material and pyrite. These aggregates are interpreted as biogenic. Comparison with Phanerozoic analogues indicates that the facies represents microbial mats formed in a shallow marine environment. Carbonate precipitation and silicification by hydrothermal fluids occurred during sedimentation and earliest diagenesis. The deciphered environment, as well as the δ13C signature of bulk organic matter (-35.3‰, are in accord with the presence of photoautotrophs. At the same time, highly abundant framboidal pyrite exhibits a sulfur isotopic signature (δ34S = +3.05‰; Δ33S = 0.268‰; and Δ36S = -0.282‰ that is consistent with microbial sulfate reduction. Taken together, our results strongly support a microbial mat origin of the black chert facies

  20. Shadow mask assisted heteroepitaxy of compound semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schallenberg, T.

    2004-07-01

    Shadow Mask assisted Molecular Beam Epitaxy (SMMBE) is a technique enabling selected area epitaxy of semiconductor heterostructures through shadow masks. The objective of this work was the development of the SMMBE technique for the reliable fabrication of compound semiconductor nanostructures of high structural and optical quality. In order to accomplish this, technological processes have been developed and optimized. One of the technological developments to this effect, which has substantially enhanced the versatility of SMMBE, is the introduction of a new type of freestanding shadow masks. A consistent model has been developed, which successfully explains the growth dynamics of molecular beam epitaxy through shadow masks. The predictions of the model regarding the growth of II-VI and III-V compounds have been tested experimentally and the dependence of the growth rates on the growth parameters has been verified. Moreover, it has been shown, that selected area epitaxy of II-VI and III-V compounds are governed by different surface kinetics. In addition to the basic surface kinetic processes described by the model, the roles of orientation and strain-dependent growth dynamics, partial shadow, and material deposition on the mask (closure of apertures) have been discussed. The resulting advanced understanding of the growth dynamics (model and basic experiments) in combination with the implementation of technical improvements has enabled the development and application of a number of different processes for the fabrication of both II-VI and III-V nanostructures. In addition to specific material properties, various other phenomena have been explo