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Sample records for deposited ultra-thin ta-c

  1. Optical properties of vacuum deposited polyaniline ultra-thin film

    International Nuclear Information System (INIS)

    Wahab, M. R. A.; Din, M.; Yunus, W. M. M.; Hasan, Z. A.; Kasim, A.

    2005-01-01

    Full text: Ultra-thin films of emeraldine base (EB) and emeraldine salt (ES) form of polyaniline (PANi) were prepared using electron-gun vacuum deposition. Thickness range studied was between 100AA and 450AA. Dielectric permittivity of the films determined from Kretchmann Configuration Surface Plasmon Resonance (SPR) angles-scanning set-up show shifts and narrowing of the SPR dip. Absorbance spectra of S-polarized and P-polarized light show the aging effect on orientation of the film. The effect of aging on its conductivity and photoluminescence is also correlated to the surface morphology

  2. Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition.

    Science.gov (United States)

    Yoo, Young Jin; Lee, Gil Ju; Jang, Kyung-In; Song, Young Min

    2017-08-29

    Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.  We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.  Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

  3. Ultra-thin Cu2ZnSnS4 solar cell by pulsed laser deposition

    DEFF Research Database (Denmark)

    Cazzaniga, Andrea Carlo; Crovetto, Andrea; Yan, Chang

    2017-01-01

    We report on the fabrication of a 5.2% efficiency Cu2ZnSnS4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed. At the ......We report on the fabrication of a 5.2% efficiency Cu2ZnSnS4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed...

  4. Reliability assessment of ultra-thin HfO2 films deposited on silicon wafer

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Chia-Wei; Chang, Yong-Qing; Yao, Chih-Kai; Liao, Jiunn-Der

    2012-01-01

    Highlights: ► Nano-mechanical properties on annealed ultra-thin HfO 2 film are studied. ► By AFM analysis, hardness of the crystallized HfO 2 film significantly increases. ► By nano-indention, the film hardness increases with less contact stiffness. ► Quality assessment on the annealed ultra-thin films can thus be achieved. - Abstract: Ultra-thin hafnium dioxide (HfO 2 ) is used to replace silicon dioxide to meet the required transistor feature size in advanced semiconductor industry. The process integration compatibility and long-term reliability for the transistors depend on the mechanical performance of ultra-thin HfO 2 films. The criteria of reliability including wear resistance, thermal fatigue, and stress-driven failure rely on film adhesion significantly. The adhesion and variations in mechanical properties induced by thermal annealing of the ultra-thin HfO 2 films deposited on silicon wafers (HfO 2 /SiO 2 /Si) are not fully understood. In this work, the mechanical properties of an atomic layer deposited HfO 2 (nominal thickness ≈10 nm) on a silicon wafer were characterized by the diamond-coated tip of an atomic force microscope and compared with those of annealed samples. The results indicate that the annealing process leads to the formation of crystallized HfO 2 phases for the atomic layer deposited HfO 2 . The HfSi x O y complex formed at the interface between HfO 2 and SiO 2 /Si, where the thermal diffusion of Hf, Si, and O atoms occurred. The annealing process increases the surface hardness of crystallized HfO 2 film and therefore the resistance to nano-scratches. In addition, the annealing process significantly decreases the harmonic contact stiffness (or thereafter eliminate the stress at the interface) and increases the nano-hardness, as measured by vertically sensitive nano-indentation. Quality assessments on as-deposited and annealed HfO 2 films can be thereafter used to estimate the mechanical properties and adhesion of ultra-thin HfO 2

  5. Reliability assessment of ultra-thin HfO{sub 2} films deposited on silicon wafer

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wei-En [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321 Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Chang, Chia-Wei [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Chang, Yong-Qing [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321 Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Yao, Chih-Kai [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Jiunn-Der, E-mail: jdliao@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Nano-mechanical properties on annealed ultra-thin HfO{sub 2} film are studied. Black-Right-Pointing-Pointer By AFM analysis, hardness of the crystallized HfO{sub 2} film significantly increases. Black-Right-Pointing-Pointer By nano-indention, the film hardness increases with less contact stiffness. Black-Right-Pointing-Pointer Quality assessment on the annealed ultra-thin films can thus be achieved. - Abstract: Ultra-thin hafnium dioxide (HfO{sub 2}) is used to replace silicon dioxide to meet the required transistor feature size in advanced semiconductor industry. The process integration compatibility and long-term reliability for the transistors depend on the mechanical performance of ultra-thin HfO{sub 2} films. The criteria of reliability including wear resistance, thermal fatigue, and stress-driven failure rely on film adhesion significantly. The adhesion and variations in mechanical properties induced by thermal annealing of the ultra-thin HfO{sub 2} films deposited on silicon wafers (HfO{sub 2}/SiO{sub 2}/Si) are not fully understood. In this work, the mechanical properties of an atomic layer deposited HfO{sub 2} (nominal thickness Almost-Equal-To 10 nm) on a silicon wafer were characterized by the diamond-coated tip of an atomic force microscope and compared with those of annealed samples. The results indicate that the annealing process leads to the formation of crystallized HfO{sub 2} phases for the atomic layer deposited HfO{sub 2}. The HfSi{sub x}O{sub y} complex formed at the interface between HfO{sub 2} and SiO{sub 2}/Si, where the thermal diffusion of Hf, Si, and O atoms occurred. The annealing process increases the surface hardness of crystallized HfO{sub 2} film and therefore the resistance to nano-scratches. In addition, the annealing process significantly decreases the harmonic contact stiffness (or thereafter eliminate the stress at the interface) and increases the nano-hardness, as measured by vertically

  6. Surface morphology and preferential orientation growth of TaC crystals formed by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Xiang, E-mail: Xiong228@sina.co [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China); Chen Zhaoke; Huang Baiyun; Li Guodong [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China); Zheng Feng [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Xiao Peng; Zhang Hongbo [State Key Lab for Powder Metallurgy, Central South University, Changsha 410083 (China)

    2009-04-02

    TaC film was deposited on (002) graphite sheet by isothermal chemical vapor deposition using TaCl{sub 5}-Ar-C{sub 3}H{sub 6} mixtures, with deposition temperature 1200 {sup o}C and pressure about 200 Pa. The influence of deposition position (or deposition rate) on preferential orientation and surface morphology of TaC crystals were investigated by X-ray diffraction and scanning electron microscopy methods. The deposits are TaC plus trace of C. The crystals are large individual columns with pyramidal-shape at deposition rate of 32.4-37.3 {mu}m/h, complex columnar at 37.3-45.6 {mu}m/h, lenticular-like at 45.6-54.6 {mu}m/h and cauliflower-like at 54.6-77.3 {mu}m/h, with <001>, near <001>, <110> and no clear preferential orientation, respectively. These results agree in part with the preditions of the Pangarov's model of the relationship between deposition rate and preferential growth orientation. The growth mechanism of TaC crystals in <001>, near <001>, <111> and no clear preferential orientation can be fairly explained by the growth parameter {alpha} with Van der Drift's model, deterioration model and Meakin model. Furthermore, a nucleation and coalescence model is also proposed to explain the formation mechanism of <110> lenticular-like crystals.

  7. Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

    Science.gov (United States)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

    A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

  8. Nanodiamond embedded ta-C composite film by pulsed filtered vacuum arc deposition from a single target

    Science.gov (United States)

    Iyer, Ajai; Etula, Jarkko; Ge, Yanling; Liu, Xuwen; Koskinen, Jari

    2016-11-01

    Detonation Nanodiamonds (DNDs) are known to have sp3 core, sp2 shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp3 content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness.

  9. Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

    Science.gov (United States)

    Giaccherini, Andrea; Russo, Francesca; Carlà, Francesco; Guerri, Annalisa; Picca, Rosaria Anna; Cioffi, Nicola; Cinotti, Serena; Montegrossi, Giordano; Passaponti, Maurizio; Di Benedetto, Francesco; Felici, Roberto; Innocenti, Massimo

    2018-02-01

    Electrochemical Atomic Layer Deposition (E-ALD), exploiting surface limited electrodeposition of atomic layers, can easily grow highly ordered ultra-thin films and 2D structures. Among other compounds CuxZnyS grown by means of E-ALD on Ag(111) has been found particularly suitable for the solar energy conversion due to its band gap (1.61 eV). However its growth seems to be characterized by a micrometric thread-like structure, probably overgrowing a smooth ultra-thin films. On this ground, a SXRD investigation has been performed, to address the open questions about the structure and the growth of CuxZnyS by means of E-ALD. The experiment shows a pseudo single crystal pattern as well as a powder pattern, confirming that part of the sample grows epitaxially on the Ag(111) substrate. The growth of the film was monitored by following the evolution of the Bragg peaks and Debye rings during the E-ALD steps. Breadth and profile analysis of the Bragg peaks lead to a qualitative interpretation of the growth mechanism. This study confirms that Zn lead to the growth of a strained Cu2S-like structure, while the growth of the thread-like structure is probably driven by the release of the stress from the epitaxial phase.

  10. Electronic structures of ultra-thin silicon carbides deposited on graphite

    International Nuclear Information System (INIS)

    Baba, Y.; Sekiguchi, T.; Shimoyama, I.; Nath, Krishna G.

    2004-01-01

    Electronic structures of ultra-thin silicon carbide films have been investigated by X-ray photoelectron spectroscopy (XPS) and Si K-edge X-ray absorption near edge structure (XANES) using linearly polarized synchrotron soft X-rays. Silicon carbide films were deposited on the surface of highly oriented pyrolytic graphite (HOPG) by ion beam deposition method. Tetramethylsilane (Si(CH 3 ) 4 ) was used as a discharge gas. The XPS and XANES features for the thick layers were similar to those for the bulk SiC. For sub-monolayered films, the Si 1s binding energy in XPS was higher by 2.5 eV than that for bulk SiC. This suggests the existence of low-dimensional SiC x where the silicon atoms are more positively charged than those in bulk SiC. After annealing the sub-monolayered film at 850 deg. C, a new peak appeared around 1840 eV in the XANES spectrum. The energy of this new peak was lower than those for any other silicon compounds. The low-energy feature of the XANES peak suggests the existence of π*-like orbitals around the silicon atom. On the basis of the polarization dependencies of the XANES spectra, it was revealed that the direction of the π*-like orbitals are nearly perpendicular to the surface. We conclude that sub-monolayered SiC x film exhibits flat-lying structure of which configuration is similar to a single sheet of graphite

  11. Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Yu-Kuang Liao

    2017-04-01

    Full Text Available Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin films with the thickness of a few nanometers on rough surfaces. We present a new ”paradigm shift” non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD and chemical bath deposition (CBD as used by the Cu(In,GaSe2 (CIGS thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase.

  12. Characterization of Ultra thin chromium layers deposited ou to SiO2 using the Le-PIXE and the RB S techniques

    International Nuclear Information System (INIS)

    Zahraman, K.; Nsouli, B.; Roumie, M.

    2007-01-01

    In this paper, we demonstrate the ability of the Le-PIXE (Low Energy PIXE) technique, using proton energies < 1 MeV, for the monitoring of the thickness and the thickness uniformity of ultra thin (0.5 nm < t < 20 nm) chromium layers deposited onto quartz substrates. Chromium is a good candidate for obtaining conductive ultra thin layers on insulator substrates such as quartz (SiO2). The resistivity of such layers is highly related to the quality of the deposited chromium film. In order to optimize the deposition process, there is a need for rapid and accurate monitoring of such films (film thickness, thickness uniformity over a big surface...). The acquisition time needed to obtain results with less than 3-4 % precision was 5 minutes for the thinnest layers. The validation for the use of the Le-PIXE technique was checked by means of conventional RB S technique.

  13. Atomic layer deposition assisted pattern transfer technology for ultra-thin block copolymer films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wenhui; Luo, Jun; Meng, Lingkuan; Li, Junjie; Xiang, Jinjuan; Li, Junfeng; Wang, Wenwu; Chen, Dapeng; Ye, Tianchun; Zhao, Chao

    2016-08-31

    As an emerging developing technique for next-generation lithography, directed self-assembly (DSA) of block copolymer (BCP) has attracted numerous attention and has been a potential alternative to supplement the intrinsic limitations of conventional photolithography. In this work, the self-assembling properties of a lamellar diblock copolymer poly(styrene-b-methylmethacrylate) (PS-b-PMMA, 22k-b-22k, L{sub 0} = 25 nm) on Si substrate and an atomic layer deposition (ALD)-assisted pattern transfer technology for the application of DSA beyond 16/14 nm complementary metal oxide semiconductor (CMOS) technology nodes, were investigated. Firstly, two key processing parameters of DSA, i.e. annealing temperatures and durations of BCP films, were optimized to achieve low defect density and high productivity. After phase separation of BCP films, self-assembling patterns of low defect density should be transferred to the substrate. However, due to the nano-scale thickness and the weak resistance of BCP films to dry etching, it is nearly impossible to transfer the BCP patterns directly to the substrate. Therefore, an ALD-based technology was explored in this work, in which deposited Al{sub 2}O{sub 3} selectively reacts with PMMA blocks thus hardening the PMMA patterns. After removing PS blocks by plasma etching, hardened PMMA patterns were left and transferred to underneath SiO{sub 2} hard mask layer. Using this patterned hard mask, nanowire array of 25 nm pitch were realized on Si substrate. From this work, a high-throughput DSA baseline flow and related ALD-assisted pattern transfer technique were developed and proved to have good capability with the mainstream CMOS technology. - Highlights: • Optimization on self-assembly process for high productivity and low defectivity • Enhancement of etching ratio and resistance by atomic layer deposition (ALD) • A hard mask was used for pattern quality improvement and contamination control.

  14. Deposition and properties of cobalt- and ruthenium-based ultra-thin films

    Science.gov (United States)

    Henderson, Lucas Benjamin

    Future copper interconnect systems will require replacement of the materials that currently comprise both the liner layer(s) and the capping layer. Ruthenium has previously been considered as a material that could function as a single material liner, however its poor ability to prevent copper diffusion makes it incompatible with liner requirements. A recently described chemical vapor deposition route to amorphous ruthenium-phosphorus alloy films could correct this problem by eliminating the grain boundaries found in pure ruthenium films. Bias-temperature stressing of capacitor structures using 5 nm ruthenium-phosphorus film as a barrier to copper diffusion and analysis of the times-to-failure at accelerated temperature and field conditions implies that ruthenium-phosphorus performs acceptably as a diffusion barrier for temperatures above 165°C. The future problems associated with the copper capping layer are primarily due to the poor adhesion between copper and the current Si-based capping layers. Cobalt, which adheres well to copper, has been widely proposed to replace the Si-based materials, but its ability to prevent copper diffusion must be improved if it is to be successfully implemented in the interconnect. Using a dual-source chemistry of dicobaltoctacarbonyl and trimethylphosphine at temperatures from 250-350°C, amorphous cobalt-phosphorus can be deposited by chemical vapor deposition. The films contain elemental cobalt and phosphorus, plus some carbon impurity, which is incorporated in the film as both graphitic and carbidic (bonded to cobalt) carbon. When deposited on copper, the adhesion between the two materials remains strong despite the presence of phosphorus and carbon at the interface, but the selectivity for growth on copper compared to silicon dioxide is poor and must be improved prior to consideration for application in interconnect systems. A single molecule precursor containing both cobalt and phosphorus atoms, tetrakis

  15. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    International Nuclear Information System (INIS)

    Alam, M. T.; Haque, M. A.; Bresnehan, M. S.; Robinson, J. A.

    2014-01-01

    Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m −1 K −1 , is lower than the bulk basal plane value (390 W m −1 K −1 ) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics

  16. Facing-target sputtering deposition of ZnO films with Pt ultra-thin layers for gas-phase photocatalytic application

    International Nuclear Information System (INIS)

    Zhang Zhonghai; Hossain, Md. Faruk.; Arakawa, Takuya; Takahashi, Takakazu

    2010-01-01

    In this paper, various zinc oxide (ZnO) films are deposited by a versatile and effective dc-reactive facing-target sputtering method. The ratios of Ar to O 2 in the mixture gas are varied from 8:2 to 6:4 at a fixed sputtering pressure of 1.0 Pa. X-ray diffraction, spectrophotometer and scanning electron microscope are used to study the crystal structure, optical property and surface morphology of the as-deposited films. The Pt ultra-thin layer, ∼2 nm thick, is deposited on the surface of ZnO film by dc diode sputtering with a mesh mask controlling the coated area. The photocatalytic activity of ZnO films and Pt-ZnO films is evaluated by decomposition of methanol under UV-vis light irradiation. The variation of photocatalytic activity depends on the ratios of Ar to O 2 , which is mainly attributed to the different grain size and carrier mobility. Though the pure ZnO film normally shows a low gas-phase photocatalytic activity, its activity is significantly enhanced by depositing Pt ultra-thin layer.

  17. High performance organic field-effect transistors with ultra-thin HfO2 gate insulator deposited directly onto the organic semiconductor

    International Nuclear Information System (INIS)

    Ono, S.; Häusermann, R.; Chiba, D.; Shimamura, K.; Ono, T.; Batlogg, B.

    2014-01-01

    We have produced stable organic field-effect transistors (OFETs) with an ultra-thin HfO 2 gate insulator deposited directly on top of rubrene single crystals by atomic layer deposition (ALD). We find that ALD is a gentle deposition process to grow thin films without damaging rubrene single crystals, as results these devices have a negligibly small threshold voltage and are very stable against gate-bias-stress, and the mobility exceeds 1 cm 2 /V s. Moreover, the devices show very little degradation even when kept in air for more than 2 months. These results demonstrate thin HfO 2 layers deposited by ALD to be well suited as high capacitance gate dielectrics in OFETs operating at small gate voltage. In addition, the dielectric layer acts as an effective passivation layer to protect the organic semiconductor

  18. Investigation of defects in ultra-thin Al{sub 2}O{sub 3} films deposited on pure copper by the atomic layer deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Chang, M.L.; Wang, L.C. [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Lin, H.C., E-mail: hclinntu@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Chen, M.J., E-mail: mjchen@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Lin, K.M. [Department of Materials Science and Engineering, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan (China)

    2015-12-30

    Graphical abstract: Some residual OH ligands originating from incomplete reaction between TMA and surface species of OH* during ALD process induce the defects in deposited Al{sub 2}O{sub 3} films. Three possible types of defects are suggested. The analytic results indicate the defects are Type-I and/or Type-II but do not directly expose the substrate, like pinholes (Type-III). - Highlights: • Oxidation trials were conducted to investigate the defects in ultra-thin Al{sub 2}O{sub 3} films deposited ALD technique on pure copper. • The residual OH ligands in the deposited Al{sub 2}O{sub 3} films induce looser micro-structure which has worse oxidation resistance. • Superficial contamination particles on substrate surface are confirmed to be one of nucleation sites of the defects. - Abstract: Al{sub 2}O{sub 3} films with various thicknesses were deposited by the atomic layer deposition (ALD) technique on pure copper at temperatures of 100–200 °C. Oxidation trials were conducted in air at 200 °C to investigate the defects in these films. The analytic results show that the defects have a looser micro-structure compared to their surroundings, but do not directly expose the substrate, like pinholes. The film's crystallinity, mechanical properties and oxidation resistance could also be affected by these defects. Superficial contamination particles on the substrate surface are confirmed to be nucleation sites of the defects. A model for the mechanism of defect formation is proposed in this study.

  19. Influence of Oxygen Concentration on the Performance of Ultra-Thin RF Magnetron Sputter Deposited Indium Tin Oxide Films as a Top Electrode for Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Jephias Gwamuri

    2016-01-01

    Full Text Available The opportunity for substantial efficiency enhancements of thin film hydrogenated amorphous silicon (a-Si:H solar photovoltaic (PV cells using plasmonic absorbers requires ultra-thin transparent conducting oxide top electrodes with low resistivity and high transmittances in the visible range of the electromagnetic spectrum. Fabricating ultra-thin indium tin oxide (ITO films (sub-50 nm using conventional methods has presented a number of challenges; however, a novel method involving chemical shaving of thicker (greater than 80 nm RF sputter deposited high-quality ITO films has been demonstrated. This study investigates the effect of oxygen concentration on the etch rates of RF sputter deposited ITO films to provide a detailed understanding of the interaction of all critical experimental parameters to help create even thinner layers to allow for more finely tune plasmonic resonances. ITO films were deposited on silicon substrates with a 98-nm, thermally grown oxide using RF magnetron sputtering with oxygen concentrations of 0, 0.4 and 1.0 sccm and annealed at 300 °C air ambient. Then the films were etched using a combination of water and hydrochloric and nitric acids for 1, 3, 5 and 8 min at room temperature. In-between each etching process cycle, the films were characterized by X-ray diffraction, atomic force microscopy, Raman Spectroscopy, 4-point probe (electrical conductivity, and variable angle spectroscopic ellipsometry. All the films were polycrystalline in nature and highly oriented along the (222 reflection. Ultra-thin ITO films with record low resistivity values (as low as 5.83 × 10−4 Ω·cm were obtained and high optical transparency is exhibited in the 300–1000 nm wavelength region for all the ITO films. The etch rate, preferred crystal lattice growth plane, d-spacing and lattice distortion were also observed to be highly dependent on the nature of growth environment for RF sputter deposited ITO films. The structural, electrical

  20. Ultra-thin layer chromatography and surface enhanced Raman spectroscopy on silver nanorod array substrates prepared by oblique angle deposition

    Science.gov (United States)

    Chen, Jing; Abell, Justin; Huang, Yao-wen; Zhao, Yiping

    2012-06-01

    We demonstrate the potential use of silver nanorod (AgNR) array substrates for on-chip separation and detection of chemical mixtures by ultra-thin layer chromatography (UTLC) and surface enhanced Raman spectroscopy (SERS). The capability of the AgNR substrates to separate different compounds in a mixture was explored using a mixture of the food colorant Brilliant Blue FCF and lactic acid, and the mixtures of Methylene Violet and BSA at various concentrations. After the UTLC process, spatially-resolved SERS spectra were collected along the mobile phase development direction and the intensities of specific SERS peaks from each component were used to generate chromatograms. The AgNR substrates demonstrate the capability of separating Brilliant Blue from lactic acid, as well as revealing the SERS signal of Methylene Violet from the massive BSA background after a simple UTLC step. This technique may have significant practical implications in actual detection of small molecules from complex food or clinical backgrounds.

  1. Metal-organic chemical vapor deposition of ultra-thin photovoltaic devices using a pyrite based p-i-n structure

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, A.J., E-mail: andy.clayton@optictechnium.com [CSER, Glyndwr University, OpTIC Technium, St Asaph, LL17 0JD (United Kingdom); Irvine, S.J.C.; Barrioz, V.; Brooks, W.S.M. [CSER, Glyndwr University, OpTIC Technium, St Asaph, LL17 0JD (United Kingdom); Zoppi, G.; Forbes, I. [NPAC, Northumbria University, Newcastle upon Tyne, NE1 8ST (United Kingdom); Rogers, K.D.; Lane, D.W.; Hutchings, K.; Roncallo, S. [Centre for Material Science and Engineering, Cranfield University, Swindon, SN6 8LA (United Kingdom)

    2011-08-31

    Ultra-thin photovoltaic (PV) devices were produced by atmospheric pressure metal organic chemical vapour deposition (AP-MOCVD) incorporating a highly absorbing intermediate sulphurised FeS{sub x} layer into a CdS/CdTe structure. X-ray diffraction (XRD) confirmed a transitional phase change to pyrite FeS{sub 2} after post growth sulphur (S) annealing of the FeS{sub x} layer between 400 deg. C and 500 deg. C. Devices using a superstrate configuration incorporating a sulphurised or non-sulphurised FeS{sub x} layer were compared to p-n devices with only a CdS/CdTe structure. Devices with sulphurised FeS{sub x} layers performed least efficiently, even though pyrite fractions were present. Rutherford back scattering (RBS) confirmed deterioration of the CdS/FeS{sub x} interface due to S inter-diffusion during the annealing process.

  2. Modification of metal–InGaAs Schottky barrier behaviour by atomic layer deposition of ultra-thin Al2O3 interlayers

    International Nuclear Information System (INIS)

    Chauhan, Lalit; Gupta, Suman; Jaiswal, Piyush; Bhat, Navakanta; Shivashankar, S.A.; Hughes, G.

    2015-01-01

    The effect of inserting ultra-thin atomic layer deposited Al 2 O 3 dielectric layers (1 nm and 2 nm thick) on the Schottky barrier behaviour for high (Pt) and low (Al) work function metals on n- and p-doped InGaAs substrates has been investigated. Rectifying behaviour was observed for the p-type substrates (both native oxide and sulphur passivated) for both the Al/p-InGaAs and Al/Al 2 O 3 /p-InGaAs contacts. The Pt contacts directly deposited on p-InGaAs displayed evidence of limited rectification which increased with Al 2 O 3 interlayer thickness. Ohmic contacts were formed for both metals on n-InGaAs in the absence of an Al 2 O 3 interlayer, regardless of surface passivation. However, limited rectifying behaviour was observed for both metals on the 2 nm Al 2 O 3 /n-InGaAs samples for the sulphur passivated InGaAs surface, indicating the importance of both surface passivation and the presence of an ultra-thin dielectric interlayer on the current–voltage characteristics displayed by these devices. - Highlights: • Investigation of the modification of metal–InGaAs Schottky barrier (SB) behaviour • Improving metal–InGaAs interface by sulphur passivation and ultrathin interlayer • Examine the effect of low work function and high work function metals on SB • Different SB behaviours observed on both n-type InGaAs and p-type InGaAs • Metal/n-InGaAs interface is more strongly pinned than the metal/p-InGaAs interface

  3. Modification of metal–InGaAs Schottky barrier behaviour by atomic layer deposition of ultra-thin Al{sub 2}O{sub 3} interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Lalit [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Gupta, Suman; Jaiswal, Piyush; Bhat, Navakanta; Shivashankar, S.A. [Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science, Bangalore 560012 (India); Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2015-08-31

    The effect of inserting ultra-thin atomic layer deposited Al{sub 2}O{sub 3} dielectric layers (1 nm and 2 nm thick) on the Schottky barrier behaviour for high (Pt) and low (Al) work function metals on n- and p-doped InGaAs substrates has been investigated. Rectifying behaviour was observed for the p-type substrates (both native oxide and sulphur passivated) for both the Al/p-InGaAs and Al/Al{sub 2}O{sub 3}/p-InGaAs contacts. The Pt contacts directly deposited on p-InGaAs displayed evidence of limited rectification which increased with Al{sub 2}O{sub 3} interlayer thickness. Ohmic contacts were formed for both metals on n-InGaAs in the absence of an Al{sub 2}O{sub 3} interlayer, regardless of surface passivation. However, limited rectifying behaviour was observed for both metals on the 2 nm Al{sub 2}O{sub 3}/n-InGaAs samples for the sulphur passivated InGaAs surface, indicating the importance of both surface passivation and the presence of an ultra-thin dielectric interlayer on the current–voltage characteristics displayed by these devices. - Highlights: • Investigation of the modification of metal–InGaAs Schottky barrier (SB) behaviour • Improving metal–InGaAs interface by sulphur passivation and ultrathin interlayer • Examine the effect of low work function and high work function metals on SB • Different SB behaviours observed on both n-type InGaAs and p-type InGaAs • Metal/n-InGaAs interface is more strongly pinned than the metal/p-InGaAs interface.

  4. UV light induced insulator-metal transition in ultra-thin ZnO/TiO{sub x} stacked layer grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Saha, D., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Misra, P., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2016-08-28

    In the present study, atomic layer deposition has been used to grow a series of Ti incorporated ZnO thin films by vertically stacking different numbers (n = 1–7) of ZnO/TiO{sub x} layers on (0001) sapphire substrates. The effects of defect states mediated chemisorption of O{sub 2} and/OH groups on the electrical properties of these films have been investigated by illuminating the samples under UV light inside a high vacuum optical cryostat. The ultra-thin film having one stacked layer (n = 1) did not show any change in its electrical resistance upon UV light exposure. On the contrary, marginal drop in the electrical resistivity was measured for the samples with n ≥ 3. Most surprisingly, the sample with n = 2 (thickness ∼ 12 nm) showed an insulator to metal transition upon UV light exposure. The temperature dependent electrical resistivity measurement on the as grown film (n = 2) showed insulating behaviour, i.e., diverging resistivity on extrapolation to T→ 0 K. However, upon UV light exposure, it transformed to a metallic state, i.e., finite resistivity at T → 0 K. Such an insulator-metal transition plausibly arises due to the de-trapping of conduction electrons from the surface defect sites which resulted in an upward shift of the Fermi level above the mobility edge. The low-temperature electron transport properties on the insulating film (n = 2) were investigated by a combined study of zero field electrical resistivity ρ(T) and magnetoresistance (MR) measurements. The observed negative MR was found to be in good agreement with the magnetic field induced suppression of quantum interference between forward-going paths of tunnelling electrons. Both ρ(T) and MR measurements provided strong evidence for the Efros-Shklovskii type variable range hopping conduction in the low-temperature (≤40 K) regime. Such studies on electron transport in ultra-thin n-type doped ZnO films are crucial to achieve optimum functionality

  5. Influences of ultra-thin Ti seed layers on the dewetting phenomenon of Au films deposited on Si oxide substrates

    Science.gov (United States)

    Kamiko, Masao; Kim, So-Mang; Jeong, Young-Seok; Ha, Jae-Ho; Koo, Sang-Mo; Ha, Jae-Geun

    2018-05-01

    The influences of a Ti seed layer (1 nm) on the dewetting phenomenon of Au films (5 nm) grown onto amorphous SiO2 substrates have been studied and compared. Atomic force microscopy results indicated that the introduction of Ti between the substrate and Au promoted the dewetting phenomenon. X-ray diffraction measurements suggested that the initial deposition of Ti promoted crystallinity of Au. A series of Auger electron spectroscopy and X-ray photoelectron spectroscopy results revealed that Ti transformed to a Ti oxide layer by reduction of the amorphous SiO2 substrate surface, and that the Ti seed layer remained on the substrate, without going through the dewetting process during annealing. We concluded that the enhancement of Au dewetting and the improvement in crystallinity of Au by the insertion of Ti could be attributed to the fact that Au location was changed from the surface of the amorphous SiO2 substrate to that of the Ti oxide layer.

  6. Nanocoatings and ultra-thin films technologies and applications

    CERN Document Server

    Tiginyanu, Ion

    2011-01-01

    Gives a comprehensive account of the developments of nanocoatings and ultra-thin films. This book covers the fundamentals, processes of deposition and characterisation of nanocoatings, as well as the applications. It is suitable for the glass and glazing, automotive, electronics, aerospace, construction and biomedical industries in particular.$bCoatings are used for a wide range of applications, from anti-fogging coatings for glass through to corrosion control in the aerospace and automotive industries. Nanocoatings and ultra-thin films provides an up-to-date review of the fundamentals, processes of deposition, characterisation and applications of nanocoatings. Part one covers technologies used in the creation and analysis of thin films, including chapters on current and advanced coating technologies in industry, nanostructured thin films from amphiphilic molecules, chemical and physical vapour deposition methods and methods for analysing nanocoatings and ultra-thin films. Part two focuses on the applications...

  7. The Effect of Film Thickness on the Gas Sensing Properties of Ultra-Thin TiO₂ Films Deposited by Atomic Layer Deposition.

    Science.gov (United States)

    Wilson, Rachel L; Simion, Cristian Eugen; Blackman, Christopher S; Carmalt, Claire J; Stanoiu, Adelina; Di Maggio, Francesco; Covington, James A

    2018-03-01

    Analyte sensitivity for gas sensors based on semiconducting metal oxides should be highly dependent on the film thickness, particularly when that thickness is on the order of the Debye length. This thickness dependence has previously been demonstrated for SnO₂ and inferred for TiO₂. In this paper, TiO₂ thin films have been prepared by Atomic Layer Deposition (ALD) using titanium isopropoxide and water as precursors. The deposition process was performed on standard alumina gas sensor platforms and microscope slides (for analysis purposes), at a temperature of 200 °C. The TiO₂ films were exposed to different concentrations of CO, CH₄, NO₂, NH₃ and SO₂ to evaluate their gas sensitivities. These experiments showed that the TiO₂ film thickness played a dominant role within the conduction mechanism and the pattern of response for the electrical resistance towards CH₄ and NH₃ exposure indicated typical n -type semiconducting behavior. The effect of relative humidity on the gas sensitivity has also been demonstrated.

  8. The Effect of Film Thickness on the Gas Sensing Properties of Ultra-Thin TiO2 Films Deposited by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Rachel L. Wilson

    2018-03-01

    Full Text Available Analyte sensitivity for gas sensors based on semiconducting metal oxides should be highly dependent on the film thickness, particularly when that thickness is on the order of the Debye length. This thickness dependence has previously been demonstrated for SnO2 and inferred for TiO2. In this paper, TiO2 thin films have been prepared by Atomic Layer Deposition (ALD using titanium isopropoxide and water as precursors. The deposition process was performed on standard alumina gas sensor platforms and microscope slides (for analysis purposes, at a temperature of 200 °C. The TiO2 films were exposed to different concentrations of CO, CH4, NO2, NH3 and SO2 to evaluate their gas sensitivities. These experiments showed that the TiO2 film thickness played a dominant role within the conduction mechanism and the pattern of response for the electrical resistance towards CH4 and NH3 exposure indicated typical n-type semiconducting behavior. The effect of relative humidity on the gas sensitivity has also been demonstrated.

  9. Ultra-thin chip technology and applications

    CERN Document Server

    2010-01-01

    Ultra-thin chips are the "smart skin" of a conventional silicon chip. This book shows how very thin and flexible chips can be fabricated and used in many new applications in microelectronics, microsystems, biomedical and other fields. It provides a comprehensive reference to the fabrication technology, post processing, characterization and the applications of ultra-thin chips.

  10. Effects of Cd{sub 1-x}Zn{sub x}S alloy composition and post-deposition air anneal on ultra-thin CdTe solar cells produced by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, A.J., E-mail: Andrew.J.Clayton@Swansea.ac.uk [Centre for Solar Energy Research, College of Engineering, Swansea University, OpTIC, St. Asaph, LL17 0JD (United Kingdom); Baker, M.A.; Babar, S.; Grilli, R. [The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Gibson, P.N. [Institute for Health and Consumer Protection, Joint Research Centre of the European Commission, 21027, Ispra, VA (Italy); Kartopu, G.; Lamb, D.A. [Centre for Solar Energy Research, College of Engineering, Swansea University, OpTIC, St. Asaph, LL17 0JD (United Kingdom); Barrioz, V. [Engineering and Environment, Department of Physics and Electrical Engineering, Northumbria University, Newcastle, NE1 8ST (United Kingdom); Irvine, S.J.C. [Centre for Solar Energy Research, College of Engineering, Swansea University, OpTIC, St. Asaph, LL17 0JD (United Kingdom)

    2017-05-01

    Ultra-thin CdTe:As/Cd{sub 1-x}Zn{sub x}S photovoltaic solar cells with an absorber thickness of 0.5 μm were deposited by metal-organic chemical vapour deposition on indium tin oxide coated boro-aluminosilicate substrates. The Zn precursor concentration was varied to compensate for Zn leaching effects after CdCl{sub 2} activation treatment. Analysis of the solar cell composition and structure by X-ray photoelectron spectroscopy depth profiling and X-ray diffraction showed that higher concentrations of Zn in the Cd{sub 1-x}Zn{sub x}S window layer resulted in suppression of S diffusion across the CdTe/Cd{sub 1-x}Zn{sub x}S interface after CdCl{sub 2} activation treatment. Excessive Zn content in the Cd{sub 1-x}Zn{sub x}S alloy preserved the spectral response in the blue region of the solar spectrum, but increased series resistance for the solar cells. A modest increase in the Zn content of the Cd{sub 1-x}Zn{sub x}S alloy together with a post-deposition air anneal resulted in an improved blue response and an enhanced open circuit voltage and fill factor. This device yielded a mean efficiency of 8.3% over 8 cells (0.25 cm{sup 2} cell area) and best cell efficiency of 8.8%. - Highlights: • CdCl{sub 2} anneal treatment resulted in S diffusing to the back contact. • High Zn levels created mixed cubic/hexagonal structure at the p-n junction. • Increased Zn in Cd{sub 1-x}Zn{sub x}S supressed S diffusion into CdTe. • Device V{sub oc} was enhanced overall with an additional back surface air anneal.

  11. Function and application of ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sasabe, Hiroyuki

    1988-02-01

    A film 10-100mm thick which is strong dynamically to some extent and has possibility to manifest fuctions of high degree different from the nature extrapolated from the normal thin film is called an ultra thin film. As an example of its concrete application, there is an electro-luminescence element which is made by laminating 5 layers of LB films of poly-L-phenylalanine on a n-GaP and has vapor-deposited gold electrodes. When voltage of 5V is imposed to it, light emission of 565nm can be observed and the emission efficiency of 2% is obtained. Besides, it has an excellent stability through the lapse of time. There is also a junction element and the ion concentration injected into macromolecule films of this element has a Gaussian distribution from the surface towards the direction of depth. Accordingly, the most active domain in terms of semiconductor as the result of doping is the location in the neighborhood of the peak. Furthermore, a photo memory is also proposed. It is applied to the artificial hemoglobine which is made of LB films, suggesting the feasibility of creating the artificial protein capable of functioning in the conditions in which the natural protein is unable to function. (5 figs, 1 tab, 7 refs)

  12. Ultra-thin Metal and Dielectric Layers for Nanophotonic Applications

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Leandro, Lorenzo; Malureanu, Radu

    2015-01-01

    In our talk we first give an overview of the various thin films used in the field of nanophotonics. Then we describe our own activity in fabrication and characterization of ultra-thin films of high quality. We particularly focus on uniform gold layers having thicknesses down to 6 nm fabricated by......-beam deposition on dielectric substrates and Al-oxides/Ti-oxides multilayers prepared by atomic layer deposition in high aspect ratio trenches. In the latter case we show more than 1:20 aspect ratio structures can be achieved....

  13. Ultra-Thin Atomic Layer Deposited TiN Films: Non-Linear I–V Behaviour and the Importance of Surface Passivation

    NARCIS (Netherlands)

    Van Hao, B.; Aarnink, Antonius A.I.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2011-01-01

    We report the electrical resistivity of atomic layer deposited TiN thin films in the thickness range 2.5-20 nm. The measurements were carried out using the circular transfer length method structures. For the films with thickness in the range of 10-20 nm, the measurements exhibited linear

  14. Towards a uniform and large-scale deposition of MoS2 nanosheets via sulfurization of ultra-thin Mo-based solid films.

    Science.gov (United States)

    Vangelista, Silvia; Cinquanta, Eugenio; Martella, Christian; Alia, Mario; Longo, Massimo; Lamperti, Alessio; Mantovan, Roberto; Basset, Francesco Basso; Pezzoli, Fabio; Molle, Alessandro

    2016-04-29

    Large-scale integration of MoS2 in electronic devices requires the development of reliable and cost-effective deposition processes, leading to uniform MoS2 layers on a wafer scale. Here we report on the detailed study of the heterogeneous vapor-solid reaction between a pre-deposited molybdenum solid film and sulfur vapor, thus resulting in a controlled growth of MoS2 films onto SiO2/Si substrates with a tunable thickness and cm(2)-scale uniformity. Based on Raman spectroscopy and photoluminescence, we show that the degree of crystallinity in the MoS2 layers is dictated by the deposition temperature and thickness. In particular, the MoS2 structural disorder observed at low temperature (<750 °C) and low thickness (two layers) evolves to a more ordered crystalline structure at high temperature (1000 °C) and high thickness (four layers). From an atomic force microscopy investigation prior to and after sulfurization, this parametrical dependence is associated with the inherent granularity of the MoS2 nanosheet that is inherited by the pristine morphology of the pre-deposited Mo film. This work paves the way to a closer control of the synthesis of wafer-scale and atomically thin MoS2, potentially extendable to other transition metal dichalcogenides and hence targeting massive and high-volume production for electronic device manufacturing.

  15. Chemical bath deposition route for the synthesis of ultra-thin CuIn(S,Se){sub 2} based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lugo, S. [Universidad Autónoma de Nuevo León (UANL), Fac. de Ciencias Químicas, Av. Universidad S/N, Ciudad Universitaria, San Nicolás de Los Garza, Nuevo León C.P. 66451 (Mexico); Sánchez, Y.; Neuschitzer, M.; Xie, H.; Insignares-Cuello, C.; Izquierdo-Roca, V. [Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona (Spain); Peña, Y. [Universidad Autónoma de Nuevo León (UANL), Fac. de Ciencias Químicas, Av. Universidad S/N, Ciudad Universitaria, San Nicolás de Los Garza, Nuevo León C.P. 66451 (Mexico); Saucedo, E., E-mail: esaucedo@irec.cat [Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona (Spain)

    2015-05-01

    CuIn(S,Se){sub 2} (CISSe) photovoltaic grade thin films are usually grown by expensive vacuum based methods or chemical routes that require highly toxic precursors. In this work, we present the synthesis of CISSe absorbers by a simple chemical bath deposition (CBD) route. In the first step, In{sub 2}S{sub 3}/Cu{sub 2−x}S stack was deposited as a precursor by CBD on Mo-coated soda lime glass substrates, using respectively thioacetamide and N,N′-dimethylthiourea as S source. Then the CISSe thin films were synthesized by the precursor's selenization at 450 °C. The obtained films were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The tetragonal chalcopyrite structure of CISSe was identified by XRD and Raman, confirming that the major part of S was replaced by Se. SEM images show a compact and homogeneous film and by cross-section the thickness was estimated to be around 700 nm. Solar cells prepared with these absorbers exhibit an open circuit voltage of 369 mV, a short circuit current density of 13.7 mA/cm{sup 2}, a fill factor of 45% and an efficiency of 2.3%. - Highlights: • Deposition of In{sub 2}S{sub 3}/Cu{sub 2−x}S multi-stacks by chemical bath deposition • Synthesis of CuIn(S,Se){sub 2} via a two stage process • Demonstration of the viability of this low cost method to produce photovoltaic grade CuIn(S,Se){sub 2}.

  16. Effects of ultraviolet irradiation treatment on low-k SiOC(-H) ultra-thin films deposited by using TMS/O2 PEALD

    International Nuclear Information System (INIS)

    Kim, Changyoung; Woo, Jongkwan; Choi, Chikyu; Navamathavan, R.

    2012-01-01

    We report on the electrical characteristics for the metal-insulator-semiconductor (MIS) structure of low-dielectric-constant SiOC(-H) films. The SiOC(-H) thin films were deposited on p-Si(100) substrates by using a plasma-enhanced atomic layer deposition (PEALD) system. To improve the structural and the electrical characteristics, we post-treated the SiOC(-H) films deposited using PEALD with ultraviolet (UV) irradiation for various time intervals. The radical intensities in the bulk plasma were observed to be influenced strongly by the radio-frequency (rf) power. A complete dissociation of the trimethylsilane (TMS) precursor took place for rf powers greater than 300 W. As the UV treatment time was increased, the bonding structure of the SiOC(-H) film clearly separated to Si-O-Si and Si-O-C bonds. Also, the fixed charge density and the interface state density on the SiOC(-H)/p-Si(100) interface decreased as the UV treatment time was increased to 6 min. Therefore, we were able to minimize the defects and to reduce the interface charge by adjusting the UV dose.

  17. Ultra thin continuously reinforced concrete pavement research in south Africa

    CSIR Research Space (South Africa)

    Perrie, BD

    2007-08-01

    Full Text Available Ultra thin continuously reinforced concrete pavements (UTCRCP), in literature also referred to as Ultra Thin Reinforced High Performance Concrete (UTHRHPC), have been used in Europe successfully as a rehabilitation measure on steel bridge decks...

  18. Ultra-thin film encapsulation processes for micro-electro-mechanical devices and systems

    International Nuclear Information System (INIS)

    Stoldt, Conrad R; Bright, Victor M

    2006-01-01

    A range of physical properties can be achieved in micro-electro-mechanical systems (MEMS) through their encapsulation with solid-state, ultra-thin coatings. This paper reviews the application of single source chemical vapour deposition and atomic layer deposition (ALD) in the growth of submicron films on polycrystalline silicon microstructures for the improvement of microscale reliability and performance. In particular, microstructure encapsulation with silicon carbide, tungsten, alumina and alumina-zinc oxide alloy ultra-thin films is highlighted, and the mechanical, electrical, tribological and chemical impact of these overlayers is detailed. The potential use of solid-state, ultra-thin coatings in commercial microsystems is explored using radio frequency MEMS as a case study for the ALD alloy alumina-zinc oxide thin film. (topical review)

  19. Study of neural cells on organic semiconductor ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bystrenova, Eva; Tonazzini, Ilaria; Stoliar, Pablo; Greco, Pierpaolo; Lazar, Adina; Dutta, Soumya; Dionigi, Chiara; Cacace, Marcello; Biscarini, Fabio [ISMN-CNR, Bologna (Italy); Jelitai, Marta; Madarasz, Emilia [IEM- HAS, Budapest (Hungary); Huth, Martin; Nickel, Bert [LMU, Munich (Germany); Martini, Claudia [Dept. PNPB, Univ. of Pisa (Italy)

    2008-07-01

    Many technological advances are currently being developed for nano-fabrication, offering the ability to create and control patterns of soft materials. We report the deposition of cells on organic semiconductor ultra-thin films. This is a first step towards the development of active bio/non bio systems for electrical transduction. Thin films of pentacene, whose thickness was systematically varied, were grown by high vacuum sublimation. We report adhesion, growth, and differentiation of human astroglial cells and mouse neural stem cells on an organic semiconductor. Viability of astroglial cells in time was measured as a function of the roughness and the characteristic morphology of ultra thin organic film, as well as the features of the patterned molecules. Optical fluorescence microscope coupled to atomic force microscope was used to monitor the presence, density and shape of deposited cells. Neural stem cells remain viable, differentiate by retinoic acid and form dense neuronal networks. We have shown the possibility to integrate living neural cells on organic semiconductor thin films.

  20. On the difference between optically and electrically determined resistivity of ultra-thin titanium nitride films

    NARCIS (Netherlands)

    Van Hao, B.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

    2013-01-01

    This work reports on the determination and comparison of the resistivity of ultra-thin atomic layer deposited titanium nitride films in the thickness range 0.65–20 nm using spectroscopic ellipsometry and electrical test structures. We found that for films thicker than 4 nm, the resistivity values

  1. Ultra-thin films for plasmonics: a technology overview

    DEFF Research Database (Denmark)

    Malureanu, Radu; Lavrinenko, Andrei

    2015-01-01

    Ultra-thin films with low surface roughness that support surface plasmon-polaritons in the infra-red and visible ranges are needed in order to improve the performance of devices based on the manipulation of plasmon propagation. Increasing amount of efforts is made in order not only to improve...... the quality of the deposited layers but also to diminish their thickness and to find new materials that could be used in this field. In this review, we consider various thin films used in the field of plasmonics and metamaterials in the visible and IR range. We focus our presentation on technological issues...... of their deposition and reported characterization of film plasmonic performance....

  2. Ultra-thin titanium nanolayers for plasmon-assisted enhancement of bioluminescence of chloroplast in biological light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Hsun Su, Yen [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Hsu, Chia-Yun; Chang, Chung-Chien [Science and Technology of Accelerator Light Source, Hsinchu 300, Taiwan (China); Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Tu, Sheng-Lung; Shen, Yun-Hwei [Department of Resource Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2013-08-05

    Ultra-thin titanium films were deposited via ultra-high vacuum ion beam sputter deposition. Since the asymmetric electric field of the metal foil plane matches the B-band absorption of chlorophyll a, the ultra-thin titanium nanolayers were able to generate surface plasmon resonance, thus enhancing the photoluminescence of chlorophyll a. Because the density of the states of plasmon resonance increases, the enhancement of photoluminescence also rises. Due to the biocompatibility and inexpensiveness of titanium, it can be utilized to enhance the bioluminescence of chloroplast in biological light emitting devices, bio-laser, and biophotonics.

  3. The strength limits of ultra-thin copper films

    Energy Technology Data Exchange (ETDEWEB)

    Wiederhirn, Guillaume

    2007-07-02

    Elucidating size effects in ultra-thin films is essential to ensure the performance and reliability of MEMS and electronic devices. In this dissertation, the influence of a capping layer on the mechanical behavior of copper (Cu) films was analyzed. Passivation is expected to shut down surface diffusion and thus to alter the contributions of dislocation- and diffusion-based plasticity in thin films. Experiments were carried out on 25 nm to 2 {mu}m thick Cu films magnetron-sputtered onto amorphous-silicon nitride coated silicon (111) substrates. These films were capped with 10 nm of aluminum oxide or silicon nitride passivation without breaking vacuum either directly after Cu deposition or after a 500 C anneal. The evolution of thermal stresses in these films was investigated mainly by the substrate curvature method between -160 C and 500 C. Negligible differences were detected for the silicon nitride vs. the aluminum oxide passivated Cu films. The processing parameters associated with the passivation deposition also had no noticeable effect on the stress-temperature behavior of the Cu. However, the thermomechanical behavior of passivated Cu films strongly depended on the Cu film thickness. For films in the micrometer range, the influence of the passivation layer was not significant, which suggests that the Cu deformed mainly by dislocation plasticity. However, diffusional creep plays an increasing role with decreasing film thickness since it becomes increasingly difficult to nucleate dislocations in smaller grains. Size effects were investigated by plotting the stress at room temperature after thermal cycling as a function of the inverse film thickness. Between 2 {mu}m and 200 nm, the room temperature stress was inversely proportional to the film thickness. The passivation exerted a strong effect on Cu films thinner than 100 nm by effectively shutting down surface diffusion mechanisms. Since dislocation processes were also shut off in these ultra-thin films, they

  4. Epitaxial stabilization of ultra thin films of electron doped manganites

    Energy Technology Data Exchange (ETDEWEB)

    Middey, S., E-mail: smiddey@uark.edu; Kareev, M.; Meyers, D.; Liu, X.; Cao, Y.; Tripathi, S.; Chakhalian, J. [Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Yazici, D.; Maple, M. B. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Ryan, P. J.; Freeland, J. W. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-05-19

    Ultra-thin films of the electron doped manganite La{sub 0.8}Ce{sub 0.2}MnO{sub 3} were grown in a layer-by-layer growth mode on SrTiO{sub 3} (001) substrates by pulsed laser interval deposition. High structural quality and surface morphology were confirmed by a combination of synchrotron based x-ray diffraction and atomic force microscopy. Resonant X-ray absorption spectroscopy measurements confirm the presence of Ce{sup 4+} and Mn{sup 2+} ions. In addition, the electron doping signature was corroborated by Hall effect measurements. All grown films show a ferromagnetic ground state as revealed by both dc magnetization and x-ray magnetic circular dichroism measurements and remain insulating contrary to earlier reports of a metal-insulator transition. Our results hint at the possibility of electron-hole asymmetry in the colossal magnetoresistive manganite phase diagram akin to the high-T{sub c} cuprates.

  5. Ultra-Thin Coatings Beautify Art

    Science.gov (United States)

    2013-01-01

    The craftsmen in the Roman Empire who constructed the Lycurgus Cup 17 centuries ago probably didn't think their artifact would survive for nearly 2,000 years as a prized possession. And they certainly couldn't have known that the technology they used to make it would eventually become an important part of space exploration. Carved from one solid mass, the cup is one of the few complete glass objects from that period, and the only one made from dichroic glass. Meaning "two-colored" in Greek, dichroic glass was originally created by adding trace amounts of gold and silver to a large volume of glass melt. The resulting medium partially reflects the light passing through it, causing an observer to see different colors depending on the direction of the light source. The Lycurgus Cup, for example, is famous for appearing green in daylight and red when lit at night, symbolic of the ripening grapes used to fill it with wine. NASA revitalized the production of dichroic glass in the 1950s and 1960s as a means of protecting its astronauts. Ordinary clear substances cannot protect human vision from the harsh rays of unfiltered sunlight, and everything from the human body to spacecraft sensors and computers are at risk if left unprotected from the radiation that permeates space. The microscopic amounts of metal present in dichroic glass make it an effective barrier against such harmful radiation. While the ancient manufacturing technique called for adding metals to glass melt, NASA developed a process in which metals are vaporized by electron beams in a vacuum chamber and then applied directly to surfaces in an ultra-thin film. The vapor condenses in the form of crystal structures, and the process is repeated for up to several dozen coatings. The resulting material, still only about 30 millionths of an inch thick, is sufficient to reflect radiation even while the glass, or polycarbonate, as in the case of space suit helmets, remains transparent to the human eye.

  6. Preparation of Ta(C)N films by pulsed high energy density plasma

    Energy Technology Data Exchange (ETDEWEB)

    Feng Wenran [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Chen Guangliang [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Zhang Yan [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Gu Weichao [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Zhang Guling [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Niu Erwu [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Liu Chizi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China); Yang Size [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100080 Beijing (China)

    2007-04-07

    The pulsed high energy density plasma (PHEDP) is generated in the working gas due to a high-voltage high-current discharge, within a coaxial gun. In PHEDP surface modification, discharge is applied for preparing the amorphous and nanostructured high-melting materials as thin films deposited on various substrates. In this investigation, Ta(C)N films were deposited using PHEDP on stainless steel. Pure tantalum and graphite were used as the inner and outer electrodes of the PHEDP coaxial gun, respectively. Nitrogen was used as the working gas and also one of the reactants. Preliminary study on the films prepared under different conditions shows that the formation of Ta(C)N is drastically voltage dependent. At lower gun voltage, no Ta(C)N was detected in the films; when the gun voltage reaches or exceeds 3.0 kV, Ta(C)N occurred. The films are composed of densely stacked nanocrystallines with diameter less than 30 nm, and some grains are within 10 nm in diameter.

  7. Ultra-thin zirconia films on Zr-alloys

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Joong Il Jake; Mayr-Schmoelzer, Wernfried; Mittendorfer, Florian; Redinger, Josef; Diebold, Ulrike; Schmid, Michael [Institute of Applied Physics, Vienna University of Technology (Austria); Li, Hao; Rupprechter, Guenther [Institute of Materials Chemistry, Vienna University of Technology (Austria)

    2014-07-01

    Zirconia ultra-thin films have been prepared by oxidation of Pt{sub 3}Zr(0001) and showed a structure equivalent to (111) of cubic zirconia. Following previous work, we have prepared ultra-thin zirconia by oxidation of a different alloy, Pd{sub 3}Zr(0001), which resulted in a similar structure with a slightly different lattice parameter, 351.2 ±0.4 pm. Unlike the oxide on Pt{sub 3}Zr, where Zr of the oxide binds to Pt in the substrate, here the oxide binds to substrate Zr via oxygen. This causes stronger distortion of the oxide structure, i.e. a stronger buckling of Zr in the oxide. After additional oxidation of ZrO{sub 2}/Pt{sub 3}Zr, a different ultra-thin zirconia phase is observed. A preliminary structure model for this film is based on (113)-oriented cubic zirconia. 3D oxide clusters are also present after growing ultra-thin zirconia films. They occur at the step edges, and the density is higher on Pd{sub 3}Zr. These clusters also appear on terraces after additional oxidation. XPS reveals different core level shifts of the oxide films, bulk, and oxide clusters.

  8. Culturing of primary rat neurons and glia on ultra-thin parylene-C

    International Nuclear Information System (INIS)

    Unsworth, C.P.; Delivopoulos, E.; Murray, A.F.

    2010-01-01

    Full text: In this article, we will describe how we have successfully cultured dissociated embryonic cortical neurons and glia from the postnatal rat hippocampus on extremely thin layers (up to 10 nm) of Parylene-C on a silicon dioxide substrate. Silicon wafers were oxidised, deposited with the biomaterial, Parylene-C, photo-lithographically patterned and plasma etched to produce chips that consisted of lines of Paryl ene-C with varying widths, thickness and lengths. The chips produced were then immersed in Horse Serum and plated with the cells. Ratios of Neurons; Glia; Cell Body were measured on, adjacent to and away from the Parylene-C. Our initial results show how these ratios remained roughly constant for ultra-thin Parylene-C thicknesses of 10 nm as compared to a benchmark thickness of 100 nm (where such cells are known to grow well). Thus, our findings demonstrate that it is possible to culture primary rat neurons and glia to practically cell membrane thicknesses of Parylene-C. Being able to culture cells on such ultra thin levels of Parylene-C will open up the possibility to develop Multi-Electrode Arrays (MEA) that can capacitively couple embedded electrodes through the parylene to the cells on its surface. Thus, providing a neat, insulated passive electrode. Only the ultra-thin thicknesses of Parylene demonstrated here would allow for the rea isation of such a technology. Hence, the outcome of this work, will be of great interest to the Neuroengineering and the Multi-Electrode Array (MEA) community, as an alternative material for the fabric tion of passive electrodes, used in capacitive coupling mode.

  9. Structural study and fabrication of nano-pattern on ultra thin film of Ag grown by magnetron sputtering

    International Nuclear Information System (INIS)

    Banerjee, S.; Mukherjee, S.; Kundu, S.

    2001-01-01

    We present the structural study of ultra thin Ag films using grazing incidence x-ray reflectivity and the modification of these films with the tip of an atomic force microscope. Ag thin films are deposited using dc magnetron sputtering on a Si(001) substrate. Initially, the growth of the film is carpet like and above a certain thickness (∼42 A) the film structure changes to form mounds. This ultra thin film of Ag having carpet-like growth can be modified by the tip of an atomic force microscope, which occurs due to the porous nature of the film. A periodic pattern of nanometer dimensions has been fabricated on this film using the atomic force microscope tip. (author)

  10. Towards bio-silicon interfaces: Formation of an ultra-thin self-hydrated artificial membrane composed of dipalmitoylphosphatidylcholine (DPPC) and chitosan deposited in high vacuum from the gas-phase

    Energy Technology Data Exchange (ETDEWEB)

    Retamal, María J., E-mail: moretama@uc.cl; Cisternas, Marcelo A.; Seifert, Birger; Volkmann, Ulrich G. [Instituto de Física, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, 7820436 Santiago (Chile); Centro de Investigación en Nanotecnología y Materiales Avanzados (CIEN-UC), Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, 7820436 Santiago (Chile); Gutierrez-Maldonado, Sebastian E.; Perez-Acle, Tomas [Computational Biology Lab (DLab), Fundación Ciencia y Vida, Av. Zañartu 1482, Santiago (Chile); Centro Interdisciplinario de Neurociencias de Valparaiso (CINV), Universidad de Valparaiso, Pasaje Harrington 287, Valparaiso (Chile); Busch, Mark; Huber, Patrick [Institute of Materials Physics and Technology, Hamburg University of Technology (TUHH), D-21073 Hamburg-Harburg (Germany)

    2014-09-14

    The recent combination of nanoscale developments with biological molecules for biotechnological research has opened a wide field related to the area of biosensors. In the last years, device manufacturing for medical applications adapted the so-called bottom-up approach, from nanostructures to larger devices. Preparation and characterization of artificial biological membranes is a necessary step for the formation of nano-devices or sensors. In this paper, we describe the formation and characterization of a phospholipid bilayer (dipalmitoylphosphatidylcholine, DPPC) on a mattress of a polysaccharide (Chitosan) that keeps the membrane hydrated. The deposition of Chitosan (∼25 Å) and DPPC (∼60 Å) was performed from the gas phase in high vacuum onto a substrate of Si(100) covered with its native oxide layer. The layer thickness was controlled in situ using Very High Resolution Ellipsometry (VHRE). Raman spectroscopy studies show that neither Chitosan nor DPPC molecules decompose during evaporation. With VHRE and Atomic Force Microscopy we have been able to detect phase transitions in the membrane. The presence of the Chitosan interlayer as a water reservoir is essential for both DPPC bilayer formation and stability, favoring the appearance of phase transitions. Our experiments show that the proposed sample preparation from the gas phase is reproducible and provides a natural environment for the DPPC bilayer. In future work, different Chitosan thicknesses should be studied to achieve a complete and homogeneous interlayer.

  11. Towards bio-silicon interfaces: Formation of an ultra-thin self-hydrated artificial membrane composed of dipalmitoylphosphatidylcholine (DPPC) and chitosan deposited in high vacuum from the gas-phase

    Science.gov (United States)

    Retamal, María J.; Cisternas, Marcelo A.; Gutierrez-Maldonado, Sebastian E.; Perez-Acle, Tomas; Seifert, Birger; Busch, Mark; Huber, Patrick; Volkmann, Ulrich G.

    2014-09-01

    The recent combination of nanoscale developments with biological molecules for biotechnological research has opened a wide field related to the area of biosensors. In the last years, device manufacturing for medical applications adapted the so-called bottom-up approach, from nanostructures to larger devices. Preparation and characterization of artificial biological membranes is a necessary step for the formation of nano-devices or sensors. In this paper, we describe the formation and characterization of a phospholipid bilayer (dipalmitoylphosphatidylcholine, DPPC) on a mattress of a polysaccharide (Chitosan) that keeps the membrane hydrated. The deposition of Chitosan (˜25 Å) and DPPC (˜60 Å) was performed from the gas phase in high vacuum onto a substrate of Si(100) covered with its native oxide layer. The layer thickness was controlled in situ using Very High Resolution Ellipsometry (VHRE). Raman spectroscopy studies show that neither Chitosan nor DPPC molecules decompose during evaporation. With VHRE and Atomic Force Microscopy we have been able to detect phase transitions in the membrane. The presence of the Chitosan interlayer as a water reservoir is essential for both DPPC bilayer formation and stability, favoring the appearance of phase transitions. Our experiments show that the proposed sample preparation from the gas phase is reproducible and provides a natural environment for the DPPC bilayer. In future work, different Chitosan thicknesses should be studied to achieve a complete and homogeneous interlayer.

  12. Towards bio-silicon interfaces: Formation of an ultra-thin self-hydrated artificial membrane composed of dipalmitoylphosphatidylcholine (DPPC) and chitosan deposited in high vacuum from the gas-phase

    International Nuclear Information System (INIS)

    Retamal, María J.; Cisternas, Marcelo A.; Seifert, Birger; Volkmann, Ulrich G.; Gutierrez-Maldonado, Sebastian E.; Perez-Acle, Tomas; Busch, Mark; Huber, Patrick

    2014-01-01

    The recent combination of nanoscale developments with biological molecules for biotechnological research has opened a wide field related to the area of biosensors. In the last years, device manufacturing for medical applications adapted the so-called bottom-up approach, from nanostructures to larger devices. Preparation and characterization of artificial biological membranes is a necessary step for the formation of nano-devices or sensors. In this paper, we describe the formation and characterization of a phospholipid bilayer (dipalmitoylphosphatidylcholine, DPPC) on a mattress of a polysaccharide (Chitosan) that keeps the membrane hydrated. The deposition of Chitosan (∼25 Å) and DPPC (∼60 Å) was performed from the gas phase in high vacuum onto a substrate of Si(100) covered with its native oxide layer. The layer thickness was controlled in situ using Very High Resolution Ellipsometry (VHRE). Raman spectroscopy studies show that neither Chitosan nor DPPC molecules decompose during evaporation. With VHRE and Atomic Force Microscopy we have been able to detect phase transitions in the membrane. The presence of the Chitosan interlayer as a water reservoir is essential for both DPPC bilayer formation and stability, favoring the appearance of phase transitions. Our experiments show that the proposed sample preparation from the gas phase is reproducible and provides a natural environment for the DPPC bilayer. In future work, different Chitosan thicknesses should be studied to achieve a complete and homogeneous interlayer

  13. Performance enhancement in organic photovoltaic solar cells using iridium (Ir) ultra-thin surface modifier (USM)

    Science.gov (United States)

    Pandey, Rina; Lim, Ju Won; Kim, Jung Hyuk; Angadi, Basavaraj; Choi, Ji Won; Choi, Won Kook

    2018-06-01

    In this study, Iridium (Ir) metallic layer as an ultra-thin surface modifier (USM) was deposited on ITO coated glass substrate using radio frequency magnetron sputtering for improving the photo-conversion efficiency of organic photovoltaic cells. Ultra-thin Ir acts as a surface modifier replacing the conventional hole transport layer (HTL) PEDOT:PSS in organic photovoltaic (OPV) cells with two different active layers P3HT:PC60BM and PTB7:PC70BM. The Ir USM (1.0 nm) coated on ITO glass substrate showed transmittance of 84.1% and work function of >5.0 eV, which is higher than that of ITO (4.5-4.7 eV). The OPV cells with Ir USM (1.0 nm) exhibits increased power conversion efficiency of 3.70% (for P3HT:PC60BM active layer) and 7.28% (for PTB7:PC70BM active layer) under 100 mW/cm2 illumination (AM 1.5G) which are higher than those of 3.26% and 6.95% for the same OPV cells but with PEDOT:PSS as HTL instead of Ir USM. The results reveal that the chemically stable Ir USM layer could be used as an alternative material for PEDOT:PSS in organic photovoltaic cells.

  14. Ultra-thin alumina and silicon nitride MEMS fabricated membranes for the electron multiplication

    Science.gov (United States)

    Prodanović, V.; Chan, H. W.; Graaf, H. V. D.; Sarro, P. M.

    2018-04-01

    In this paper we demonstrate the fabrication of large arrays of ultrathin freestanding membranes (tynodes) for application in a timed photon counter (TiPC), a novel photomultiplier for single electron detection. Low pressure chemical vapour deposited silicon nitride (Si x N y ) and atomic layer deposited alumina (Al2O3) with thicknesses down to only 5 nm are employed for the membrane fabrication. Detailed characterization of structural, mechanical and chemical properties of the utilized films is carried out for different process conditions and thicknesses. Furthermore, the performance of the tynodes is investigated in terms of secondary electron emission, a fundamental attribute that determines their applicability in TiPC. Studied features and presented fabrication methods may be of interest for other MEMS application of alumina and silicon nitride as well, in particular where strong ultra-thin membranes are required.

  15. Highly reflective rear surface passivation design for ultra-thin Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Vermang, Bart, E-mail: Bart.Vermang@angstrom.uu.se [Ångström Solar Center, University of Uppsala, Uppsala 75121 (Sweden); ESAT-KU Leuven, University of Leuven, Leuven 3001 (Belgium); Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika [Ångström Solar Center, University of Uppsala, Uppsala 75121 (Sweden); Gunnarsson, Rickard; Pilch, Iris; Helmersson, Ulf [Plasma & Coatings Physics, University of Linköping, Linköping 58183 (Sweden); Kotipalli, Ratan; Henry, Frederic; Flandre, Denis [ICTEAM/IMNC, Université Catholique de Louvain, Louvain-la-Neuve 1348 (Belgium)

    2015-05-01

    Al{sub 2}O{sub 3} rear surface passivated ultra-thin Cu(In,Ga)Se{sub 2} (CIGS) solar cells with Mo nano-particles (NPs) as local rear contacts are developed to demonstrate their potential to improve optical confinement in ultra-thin CIGS solar cells. The CIGS absorber layer is 380 nm thick and the Mo NPs are deposited uniformly by an up-scalable technique and have typical diameters of 150 to 200 nm. The Al{sub 2}O{sub 3} layer passivates the CIGS rear surface between the Mo NPs, while the rear CIGS interface in contact with the Mo NP is passivated by [Ga]/([Ga] + [In]) (GGI) grading. It is shown that photon scattering due to the Mo NP contributes to an absolute increase in short circuit current density of 3.4 mA/cm{sup 2}; as compared to equivalent CIGS solar cells with a standard back contact. - Highlights: • Proof-of-principle ultra-thin CIGS solar cells have been fabricated. • The cells have Mo nano-particles (NPs) as local rear contacts. • An Al{sub 2}O{sub 3} film passivates the CIGS rear surface between these nano-particles. • [Ga]/([Ga] + [In]) grading is used to reduce Mo-NP/CIGS interface recombination.

  16. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    International Nuclear Information System (INIS)

    Singh, Akhilesh Kumar; Hsu, Jen-Hwa; Perumal, Alagarsamy

    2016-01-01

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)] 2 /FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (T A =200, 300 and 400 °C). Structural analyzes reveal that the films annealed at T A ≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at T A =300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M–H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), T A and temperature. A large reduction in coercivity (H C ) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of H C (T), i.e., a broad minimum in H C (T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the H C (T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (T C ) with T A (x). The multilayer films annealed at 200 °C exhibit low value of T C with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest T C with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and nature of interfaces. - Highlights: • Preparation and

  17. Design of an ultra-thin dual band infrared system

    Science.gov (United States)

    Du, Ke; Cheng, Xuemin; Lv, Qichao; Hu, YiFei

    2014-11-01

    The ultra-thin imaging system using reflective multiple-fold structure has smaller volume and less weight while maintaining high resolution compared with conventional optical systems. The multi-folded approach can significantly extend focal distance within wide spectral range without incurring chromatic aberrations. In this paper, we present a dual infrared imaging system of four-folded reflection with two air-spaced concentric reflective surfaces. The dual brand IR system has 107mm effective focal length, 0.7NA, +/-4° FOV, and 50mm effective aperture with 80mm outer diameter into a 25mm total thickness, which spectral response is 3~12μm.

  18. Ultra-thin infrared metamaterial detector for multicolor imaging applications.

    Science.gov (United States)

    Montoya, John A; Tian, Zhao-Bing; Krishna, Sanjay; Padilla, Willie J

    2017-09-18

    The next generation of infrared imaging systems requires control of fundamental electromagnetic processes - absorption, polarization, spectral bandwidth - at the pixel level to acquire desirable information about the environment with low system latency. Metamaterial absorbers have sparked interest in the infrared imaging community for their ability to enhance absorption of incoming radiation with color, polarization and/or phase information. However, most metamaterial-based sensors fail to focus incoming radiation into the active region of a ultra-thin detecting element, thus achieving poor detection metrics. Here our multifunctional metamaterial absorber is directly integrated with a novel mid-wave infrared (MWIR) and long-wave infrared (LWIR) detector with an ultra-thin (~λ/15) InAs/GaSb Type-II superlattice (T2SL) interband cascade detector. The deep sub-wavelength metamaterial detector architecture proposed and demonstrated here, thus significantly improves the detection quantum efficiency (QE) and absorption of incoming radiation in a regime typically dominated by Fabry-Perot etalons. Our work evinces the ability of multifunctional metamaterials to realize efficient wavelength selective detection across the infrared spectrum for enhanced multispectral infrared imaging applications.

  19. Carbonitrides in the system Ta-TaC-TaN

    International Nuclear Information System (INIS)

    Ritzhaupt-Kleissl, H.J.

    1975-04-01

    Specimens have been prepared in the binary section TaC-TaN and the carbon-rich region of the Ta-TaC-TaN system by hot pressing and subsequent homogenisation. It was possible to prepare nitrogen-rich carbonitrides by homogenizing them at 1,800 0 C under a nitrogen-pressure of 50 at up to the composition of 70 mol% TaN/30 mol% TaC. Those carbonitrides containing less than 25 at% nitrogen could be prepared by homogenisation at 2,000 0 C under a nitrogen-pressure of 600 Torr. Subsequent ageing at temperatures of 1,200, 1,300 and 1,400 0 C in high vacuum as well as at 1 at nitrogen resulted in the appearance of precipitations of epsilon-TaN, β-Ta 2 (C,N) and of the zeta-phase. The type amount and shape of the precipitated phases are dependent on the ageing conditions and on the composition the specimens. Single phase specimens with compositions close to the non-metal deficient phase boundary as well as multi-phase carbonitrides with high nitrogen contents and very fine precipitates showed values of the Vickers-hardness up to 3,000 kp/mm 2 at room temperature. With regard to the hot hardness up to a temperature of 1,300 0 C specimens aged in high vacuum were superior to those which were only homogenized as well as to those aged under a nitrogen-pressure of 1 at. On an average the best hardness-values have been found at room temperature as well as at temperatures up to 1,300 0 C for carbonitrides consisting of 50 mol% TaC/50 mol% TaN after homogenisation and subsequent ageing for 40 h at 1,300 0 C. (orig.) [de

  20. Discharge amplified photo-emission from ultra-thin films applied to tuning work function of transparent electrodes in organic opto-electronic devices

    International Nuclear Information System (INIS)

    Gentle, A.R.; Smith, G.B.; Watkins, S.E.

    2013-01-01

    A novel photoemission technique utilising localised discharge amplification of photo-yield is reported. It enables fast, accurate measurement of work function and ionisation potential for ultra-thin buffer layers vacuum deposited onto single and multilayer transparent conducting electrodes for organic solar cells and OLED's. Work function in most traditional transparent electrodes has to be raised to maximise charge transfer while high transmittance and high conductance must be retained. Results are presented for a range of metal oxide buffers, which achieve this goal. This compact photo-yield spectroscopy tool with its fast turn-around has been a valuable development aid since ionisation potential can vary significantly as deposition conditions change slightly, and as ultra-thin films grow. It has also been useful in tracking the impact of different post deposition cleaning treatments along with some storage and transport protocols, which can adversely reduce ionisation potential and hence subsequent device performance.

  1. Mechanical and electrical properties of ultra-thin chips and flexible electronics assemblies during bending

    NARCIS (Netherlands)

    Van Den Ende, D.A.; Van De Wiel, H.J.; Kusters, R.H.L.; Sridhar, A.; Schram, J.F.M.; Cauwe, M.; Van Den Brand, J.

    2014-01-01

    Ultra-thin chips of less than 20 μm become flexible, allowing integration of silicon IC technology with highly flexible electronics such as food packaging sensor systems or healthcare and sport monitoring tags as wearable patches or even directly in clothing textile. The ultra-thin chips in these

  2. Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 solar cells

    International Nuclear Information System (INIS)

    Yin, Guanchao; Steigert, Alexander; Andrae, Patrick; Goebelt, Manuela; Latzel, Michael; Manley, Phillip; Lauermann, Iver; Christiansen, Silke; Schmid, Martina

    2015-01-01

    Graphical abstract: Plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 (CIGSe) solar cells are investigated. Ag diffusion is successfully passivated by reducing the substrate temperature and introducing a 50 nm atomic layer deposition (ALD) prepared Al_2O_3 film. This clears the thermal obstacle in incorporating Ag nanoparticles in CIGSe solar cells. Simulations show that Ag nanoparticles have the potential to greatly enhance the light absorption in ultra-thin CIGSe solar cells. - Highlights: • Ag nanoparticles are able to diffuse through ITO substrate into CIGSe absorber even at a low substrate temperature of 440 °C. • The direction (inserting a dielectric passivation layer) to thermally block the Ag diffusion and the requirements for the passivation layer are indicated and generalized. • An atomic layer deposited Al_2O_3 layer is experimentally proved to be able to thermally passivate the Ag nanoparticles, which clears the thermal obstacle in using Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. • It is theoretically proved that the Ag nanoparticles as a back reflector have the potential to effectively enhance the absorption in ultra-thin CIGSe solar cells. - Abstract: Integration of plasmonic Ag nanoparticles as a back reflector in ultra-thin Cu(In,Ga)Se_2 (CIGSe) solar cells is investigated. X-ray photoelectron spectroscopy results show that Ag nanoparticles underneath a Sn:In_2O_3 back contact could not be thermally passivated even at a low substrate temperature of 440 °C during CIGSe deposition. It is shown that a 50 nm thick Al_2O_3 film prepared by atomic layer deposition is able to block the diffusion of Ag, clearing the thermal obstacle in utilizing Ag nanoparticles as a back reflector in ultra-thin CIGSe solar cells. Via 3-D finite element optical simulation, it is proved that the Ag nanoparticles show the potential to contribute the effective absorption in CIGSe solar cells.

  3. A novel high performance, ultra thin heat sink for electronics

    International Nuclear Information System (INIS)

    Escher, W.; Michel, B.; Poulikakos, D.

    2010-01-01

    We present an ultra thin heat sink for electronics, combining optimized impinging slot-jets, micro-channels and manifolds for efficient cooling. We first introduce a three-dimensional numerical model of the heat transfer structure, to investigate its hydrodynamic and thermal performance and its sensitivity to geometric parameters. In a second step we propose a three-dimensional hydrodynamic numerical model representing the complete system. Based on this model we design a novel manifold providing uniform fluid distribution. In order to save computational time a simpler semi-empirical model is proposed and validated. The semi-empirical model allows a robust optimization of the heat sink geometric parameters. The design is optimized for a 2 x 2 cm 2 chip and provides a total thermal resistance of 0.087 cm 2 K/W for flow rates 2 for a temperature difference between fluid inlet and chip of 65 K.

  4. TaC Studios New Construction Test House

    Energy Technology Data Exchange (ETDEWEB)

    Butler, T. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Curtis, O. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Kim, E. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Roberts, S. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Stephenson, R. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2013-03-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA, in the mixed humid climate zone. This home will serve as a model home for the builder partner and addresses Building America energy savings targets through the planning and implementation of a design package will serve as a basis of design for the builder partner’s future homes. As a BA test house, this home will be evaluated to detail whole house energy use, end use loads, and HVAC and hot water efficiency.

  5. Spectroelectrochemical properties of ultra-thin indium tin oxide films under electric potential modulation

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xue, E-mail: x0han004@louisville.edu; Mendes, Sergio B., E-mail: sbmend01@louisville.edu

    2016-03-31

    In this work, the spectroscopic properties of ultra-thin ITO films are characterized under an applied electric potential modulation. To detect minute spectroscopic features, the ultra-thin ITO film was coated over an extremely sensitive single-mode integrated optical waveguide, which provided a long pathlength with more than adequate sensitivity for optical interrogation of the ultra-thin film. Experimental configurations with broadband light and several laser lines at different modulation schemes of an applied electric potential were utilized to elucidate the nature of intrinsic changes. The imaginary component of the refractive index (absorption coefficient) of the ultra-thin ITO film is unequivocally shown to have a dependence on the applied potential and the profile of this dependence changes substantially even for wavelengths inside a small spectral window (500–600 nm). The characterization technique and the data reported here can be crucial to several applications of the ITO material as a transparent conductive electrode, as for example in spectroelectrochemical investigations of surface-confined redox species. - Highlights: • Optical waveguides are applied for spectroscopic investigations of ultra-thin films. • Ultra-thin ITO films in aqueous environment are studied under potential modulation. • Unique spectroscopic features of ultra-thin ITO films are unambiguously observed.

  6. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Demes, Thomas [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Ternon, Céline, E-mail: celine.ternon@grenoble-inp.fr [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, LTM, F-38000 Grenoble (France); Morisot, Fanny [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Riassetto, David [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Legallais, Maxime [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France); Univ. Grenoble Alpes, CNRS, Grenoble-INP" 2, IMEP-LaHC, F-38000 Grenoble (France); Roussel, Hervé; Langlet, Michel [Univ. Grenoble Alpes, CNRS, Grenoble-INP, LMGP, F-38000 Grenoble (France)

    2017-07-15

    Highlights: • ZnO nanowires are grown on sol-gel ZnO seed layers by hydrothermal synthesis. • Ultra-thin and high aspect ratio nanowires are obtained without using additives. • Nanowire diameter is 20–25 nm regardless of growth time and seed morphology. • A nanowire growth model is developed on the basis of thermodynamic considerations. • The nanowires are intended for integration into electrically conductive nanonets. - Abstract: Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20–25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20–25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  7. Interface analysis of Ge ultra thin layers intercalated between GaAs substrates and oxide stacks

    Energy Technology Data Exchange (ETDEWEB)

    Molle, Alessandro, E-mail: alessandro.molle@mdm.infm.i [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Lamagna, Luca; Spiga, Sabina [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Fanciulli, Marco [Laboratorio Nazionale MDM, CNR-INFM, Via C. Olivetti 2, 20041 Agrate Brianza (MI) (Italy); Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, Milano (Italy); Brammertz, Guy; Meuris, Marc [IMEC, 75 Kapeldreef, B-3001 Leuven (Belgium)

    2010-01-01

    Capping III-V compound surfaces with Ge ultra-thin layer might be a viable pathway to passivate the electrically active interface traps which usually jeopardize the integration of III-V materials in metal-oxide-semiconductor devices. As the physical nature of such traps is intrinsically related to the chemical details of the interface composition, the structural and compositional features of the Ge/GaAs interface were thoroughly investigated in two different configurations, the atomic layer deposition of La-doped ZrO{sub 2} films on Ge-capped GaAs and the ultra-high vacuum based molecular beam deposition of GeO{sub 2}/Ge double stack on in situ prepared GaAs. In the former case, the intercalation of a Ge interface layer is shown to suppress the concentration of interface Ga-O, As-O and elemental As bonding which were significantly detected in case of the direct oxide deposition on GaAs. In the latter case, the incidence of two different in situ surface preparations, the Ar sputtering and the atomic H cleaning, on the interface composition is elucidated and the beneficial role played by the atomic H exposure in reducing the semiconductor-oxygen bonds at the interface level is demonstrated.

  8. Phase diagrams for pseudo-binary carbide systems TiC-NbC, TiC-TaC, ZrC-NbC, ZrC-TaC and HfC-TaC

    International Nuclear Information System (INIS)

    Gusev, A.I.

    1985-01-01

    Parameters of interaction and energy of mutual exchange in the liquid and solid phases of pseudobinary TiC-NbC, TiC-TaC, ZrC-NbC, ZrC-TaC, HfC-TaC systems are calculated with account of dependence on composition and temperature. Positions of liquidus-solidus phase boundaries on the phase diagrams of the mentioned systems are calculated on the basis of the determined mutual exchange energies in approximati.on of subregular solutions. The existance of latent decomposition ranges in the solid phase on the phase diagrams of the investgated systems is established

  9. Ultra-Thin Solid-State Nanopores: Fabrication and Applications

    Science.gov (United States)

    Kuan, Aaron Tzeyang

    Solid-state nanopores are a nanofluidic platform with unique advantages for single-molecule analysis and filtration applications. However, significant improvements in device performance and scalable fabrication methods are needed to make nanopore devices competitive with existing technologies. This dissertation investigates the potential advantages of ultra-thin nanopores in which the thickness of the membrane is significantly smaller than the nanopore diameter. Novel, scalable fabrication methods were first developed and then utilized to examine device performance for water filtration and single molecule sensing applications. Fabrication of nanometer-thin pores in silicon nitride membranes was achieved using a feedback-controlled ion beam method in which ion sputtering is arrested upon detection of the first few ions that drill through the membrane. Performing fabrication at liquid nitrogen temperatures prevents surface atom rearrangements that have previously complicated similar processes. A novel cross-sectional imaging method was also developed to allow careful examination of the full nanopore geometry. Atomically-thin graphene nanopores were fabricated via an electrical pulse method in which sub-microsecond electrical pulses applied across a graphene membrane in electrolyte solution are used to create a defect in the membrane and controllably enlarge it into a nanopore. This method dramatically increases the accuracy and reliability of graphene nanopore production, allowing consistent production of single nanopores down to subnanometer sizes. In filtration applications in which nanopores are used to selectively restrict the passage of dissolved contaminants, ultra-thin nanopores minimize the flow resistance, increasing throughput and energy-efficiency. The ability of graphene nanopores to separate different ions was characterized via ionic conductance and reversal potential measurements. Graphene nanopores were observed to conduct cations preferentially over

  10. Fatigue-resistant epitaxial Pb(Zr,Ti)O3 capacitors on Pt electrode with ultra-thin SrTiO3 template layers

    International Nuclear Information System (INIS)

    Takahara, Seiichi; Morimoto, Akiharu; Kawae, Takeshi; Kumeda, Minoru; Yamada, Satoru; Ohtsubo, Shigeru; Yonezawa, Yasuto

    2008-01-01

    Lead zirconate-titanate Pb(Zr,Ti)O 3 (PZT) capacitors with Pt bottom electrodes were prepared on MgO substrates by pulsed laser deposition (PLD) technique employing SrTiO 3 (STO) template layer. Perovskite PZT thin films are prepared via stoichiometric target using the ultra-thin STO template layers while it is quite difficult to obtain the perovskite PZT on Pt electrode via stoichiometric target in PLD process. The PZT capacitor prepared with the STO template layer showed good hysteresis and leakage current characteristics, and it showed an excellent fatigue resistance. The ultra-thin STO template layers were characterized by angle-resolved X-ray photoelectron spectroscopy measurement. The effect of the STO template layer is discussed based on the viewpoint of the perovskite nucleation and diffusion of Pb and O atoms

  11. Role of interlayer coupling in ultra thin MoS2

    KAUST Repository

    Cheng, Yingchun; Zhu, Zhiyong; Schwingenschlö gl, Udo

    2012-01-01

    The effects of interlayer coupling on the vibrational and electronic properties of ultra thin MoS 2 were studied by ab initio calculations. For smaller slab thickness, the interlayer distance is significantly elongated because of reduced interlayer

  12. Feasibility of Ultra-Thin Fiber-Optic Dosimeters for Radiotherapy Dosimetry.

    Science.gov (United States)

    Lee, Bongsoo; Kwon, Guwon; Shin, Sang Hun; Kim, Jaeseok; Yoo, Wook Jae; Ji, Young Hoon; Jang, Kyoung Won

    2015-11-17

    In this study, prototype ultra-thin fiber-optic dosimeters were fabricated using organic scintillators, wavelength shifting fibers, and plastic optical fibers. The sensor probes of the ultra-thin fiber-optic dosimeters consisted of very thin organic scintillators with thicknesses of 100, 150 and 200 μm. These types of sensors cannot only be used to measure skin or surface doses but also provide depth dose measurements with high spatial resolution. With the ultra-thin fiber-optic dosimeters, surface doses for gamma rays generated from a Co-60 therapy machine were measured. Additionally, percentage depth doses in the build-up regions were obtained by using the ultra-thin fiber-optic dosimeters, and the results were compared with those of external beam therapy films and a conventional fiber-optic dosimeter.

  13. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Akhilesh Kumar [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Hsu, Jen-Hwa [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2016-11-15

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)]{sub 2}/FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (T{sub A}=200, 300 and 400 °C). Structural analyzes reveal that the films annealed at T{sub A}≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at T{sub A}=300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M–H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), T{sub A} and temperature. A large reduction in coercivity (H{sub C}) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of H{sub C}(T), i.e., a broad minimum in H{sub C}(T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the H{sub C}(T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (T{sub C}) with T{sub A} (x). The multilayer films annealed at 200 °C exhibit low value of T{sub C} with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest T{sub C} with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and

  14. Probing stress state and phase content in ultra-thin Ta films

    International Nuclear Information System (INIS)

    Whitacre, J.F.; Yalisove, S.M.; Bilello, J.C.; Rek, Z.U.

    1998-01-01

    Ta films 25 angstrom to 200 angstrom in thickness were sputter-deposited using different sputter gas (Ar) pressures and cathode power settings. The average in-plane stresses were determined using double crystal diffraction topography (DCDT). X-ray analysis (using the grazing incidence x-ray scattering (GIXS) geometry) was performed using a synchrotron light source. To study microstructure and phase content, transmission electron microscopy (TEM) and transmission electron diffraction (TED) were used. Well resolved x-ray patterns were collected for all of the films. The DCDT stress data was found to be consistent with stress effects evidence in the GIXS data. In general, residual stress state was not strongly dependent upon Ar pressure. The strongest evidence of amorphous content was found in both x-ray and TED data taken from 25 angstrom thick films deposited using 2mTorr Ar pressure and 460 W cathode power. These results show that it is possible to create and study ultra-thin Ta films which possess a range of residual stresses and phase compositions

  15. Thin TaC layer produced by ion mixing

    DEFF Research Database (Denmark)

    Barna, Árpád; Kotis, László; Pécz, Béla

    2012-01-01

    in strongly asymmetric ion mixing; the carbon was readily transported to the Ta layer, while the reverse process was much weaker. Because of the asymmetrical transport the C/TaC interface remained sharp independently from the applied fluence. The carbon transported to the Ta layer formed Ta......Ion-beam mixing in C/Ta layered systems was investigated. C 8nm/Ta 12nm and C 20nm/Ta 19nm/C 20nm layer systems were irradiated by Ga+ ions of energy in the range of 2–30keV. In case of the 8nm and 20nm thick C cover layers applying 5–8keV and 20–30keV Ga+ ion energy, respectively resulted...

  16. TaC Studios New Construction Test House

    Energy Technology Data Exchange (ETDEWEB)

    Butler, T.; Curtis, O.; Kim, E.; Roberts, S.; Stephenson, R.

    2013-03-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA in the mixed humid climate zone. This home will serve as a model home for the builder partner and addresses Building America energy savings targets through the planning and implementation of a design package will serve as a basis of design for the builder partner's future homes. As a BA test house, this home will be evaluated to detail whole house energy use, end use loads, and HVAC and hot water efficiency.

  17. Growth of ultra-thin Ag films on Ni(111)

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Axel; Flege, Jan Ingo; Falta, Jens [Institute of Solid State Physics, University of Bremen, 28359 Bremen (Germany); Senanayake, Sanjaya [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Alamgir, Faisal [Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2009-07-01

    The physical and chemical properties of ultra-thin metal films on metallic substrates strongly depend on their morphology and the structure of the buried interface. Hence, detailed knowledge of the growth mechanisms is essential for the creation of new functional materials with novel characteristics. In this contribution, we present a comprehensive structural study of the growth and properties of epitaxial Ag films on Ni(111) by in-situ low energy electron microscopy (LEEM). For lower temperatures, the growth of the Ag film proceeds in a Stranski-Krastanov mode after completion of the wetting layer, while for higher temperatures layer-by-layer growth is observed. Quantitative information about the film structure were obtained by analyzing the intensity-voltage (I-V) dependence of the local electron reflectivity (IV-LEEM). The corresponding I(V) spectra showed intensity oscillations depending on local thickness of the Ag film due to the quantum size effect (QSE). Modeling of the I(V) spectra was performed both within the framework of a one-dimensional Kronig-Penney model and multiple scattering IV-LEED calculations. The results of both approaches concerning the variation of the layer spacings and interface characteristics for different temperatures and film thicknesses will be discussed.

  18. Axial ion channeling patterns from ultra-thin silicon membranes

    International Nuclear Information System (INIS)

    Motapothula, M.; Dang, Z.Y.; Venkatesan, T.; Breese, M.B.H.; Rana, M.A.; Osman, A.

    2012-01-01

    We present channeling patterns produced by MeV protons transmitted through 55 nm thick [0 0 1] silicon membranes showing the early evolution of the axially channeled beam angular distribution for small tilts away from the [0 0 1], [0 1 1] and [1 1 1] axes. Instead of a ring-like “doughnut” distribution previously observed at small tilts to major axes in thicker membranes, geometric shapes such as squares and hexagons are observed along different axes in ultra-thin membranes. The different shapes arise because of the highly non-equilibrium transverse momentum distribution of the channeled beam during its initial propagation in the crystal and the reduced multiple scattering which allows the fine angular structure to be resolved. We describe a simple geometric construction of the intersecting planar channels at an axis to gain insight into the origin of the geometric shapes observed in such patterns and how they evolve into the ‘doughnut’ distributions in thicker crystals.

  19. Ultra thin layer activation by recoil implantation of radioactive heavy ions. Applicability in wear and corrosion studies

    International Nuclear Information System (INIS)

    Lacroix, O.; Sauvage, T.; Blondiaux, G.; Guinard, L.

    1997-07-01

    A new calibration procedure is proposed for the application of recoil implantation of radioactive heavy ions (energies between a few hundred keV and a few MeV) into the near surface of materials as part of a research programme on sub-micrometric wear or corrosion phenomena. The depth profile of implanted radioelements is performed by using ultra thin deposited films obtained by cathode sputtering under argon plasma. Two curves for 56 Co ion in nickel have been determined for implantation depths of 110 and 200 nm, respectively, and stress the feasibility and reproducibility of this method for such activated depths. The achieved surface loss detection sensitivities are about 1 and 2 nm respectively. The on line detection mode is performed directly on the sample of interest. A general description of the method is presented. A study of the reaction kinematics followed by a general treatment on the irradiation parameters to be adopted are also developed with the intention of using the ultra thin layer activation method (UTLA) to further applications in research and industry. (author)

  20. Silicon nitride gradient film as the underlayer of ultra-thin tetrahedral amorphous carbon overcoat for magnetic recording slider

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guigen, E-mail: wanggghit@yahoo.com [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Kuang Xuping; Zhang Huayu; Zhu Can [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Han Jiecai [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Zuo Hongbo [Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Ma Hongtao [SAE Technologies Development (Dongguan) Co., Ltd., Dongguan 523087 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The ultra-thin carbon films with different silicon nitride (Si-N) film underlayers were prepared. Black-Right-Pointing-Pointer It highlighted the influences of Si-N underlayers. Black-Right-Pointing-Pointer The carbon films with Si-N underlayers obtained by nitriding especially at the substrate bias of -150 V, can exhibit better corrosion protection properties - Abstract: There are higher technical requirements for protection overcoat of magnetic recording slider used in high-density storage fields for the future. In this study, silicon nitride (Si-N) composition-gradient films were firstly prepared by nitriding of silicon thin films pre-sputtered on silicon wafers and magnetic recording sliders, using microwave electron cyclotron resonance plasma source. The ultra-thin tetrahedral amorphous carbon films were then deposited on the Si-N films by filtered cathodic vacuum arc method. Compared with amorphous carbon overcoats with conventional silicon underlayers, the overcoats with Si-N underlayers obtained by plasma nitriding especially at the substrate bias of -150 V, can provide better corrosion protection for high-density magnetic recording sliders.

  1. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Science.gov (United States)

    Demes, Thomas; Ternon, Céline; Morisot, Fanny; Riassetto, David; Legallais, Maxime; Roussel, Hervé; Langlet, Michel

    2017-07-01

    Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20-25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20-25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  2. Silicon nitride gradient film as the underlayer of ultra-thin tetrahedral amorphous carbon overcoat for magnetic recording slider

    International Nuclear Information System (INIS)

    Wang Guigen; Kuang Xuping; Zhang Huayu; Zhu Can; Han Jiecai; Zuo Hongbo; Ma Hongtao

    2011-01-01

    Highlights: ► The ultra-thin carbon films with different silicon nitride (Si-N) film underlayers were prepared. ► It highlighted the influences of Si-N underlayers. ► The carbon films with Si-N underlayers obtained by nitriding especially at the substrate bias of −150 V, can exhibit better corrosion protection properties - Abstract: There are higher technical requirements for protection overcoat of magnetic recording slider used in high-density storage fields for the future. In this study, silicon nitride (Si-N) composition-gradient films were firstly prepared by nitriding of silicon thin films pre-sputtered on silicon wafers and magnetic recording sliders, using microwave electron cyclotron resonance plasma source. The ultra-thin tetrahedral amorphous carbon films were then deposited on the Si-N films by filtered cathodic vacuum arc method. Compared with amorphous carbon overcoats with conventional silicon underlayers, the overcoats with Si-N underlayers obtained by plasma nitriding especially at the substrate bias of −150 V, can provide better corrosion protection for high-density magnetic recording sliders.

  3. Characterization of ultra-thin TiO2 films grown on Mo(112)

    International Nuclear Information System (INIS)

    Kumar, D.; Chen, M.S.; Goodman, D.W.

    2006-01-01

    Ultra-thin TiO 2 films were grown on a Mo(112) substrate by stepwise vapor depositing of Ti onto the sample surface followed by oxidation at 850 K. X-ray photoelectron spectroscopy showed that the Ti 2p peak position shifts from lower to higher binding energy with an increase in the Ti coverage from sub- to multilayer. The Ti 2p peak of a TiO 2 film with more than a monolayer coverage can be resolved into two peaks, one at 458.1 eV corresponding to the first layer, where Ti atoms bind to the substrate Mo atoms through Ti-O-Mo linkages, and a second feature at 458.8 eV corresponding to multilayer TiO 2 where the Ti atoms are connected via Ti-O-Ti linkages. Based on these assignments, the single Ti 2p 3/2 peak at 455.75 eV observed for the Mo(112)-(8 x 2)-TiO x monolayer film can be assigned to Ti 3+ , consistent with our previous results obtained with high-resolution electron energy loss spectroscopy

  4. On-chip ultra-thin layer chromatography and surface enhanced Raman spectroscopy.

    Science.gov (United States)

    Chen, Jing; Abell, Justin; Huang, Yao-wen; Zhao, Yiping

    2012-09-07

    We demonstrate that silver nanorod (AgNR) array substrates can be used for on-chip separation and detection of chemical mixtures by combining ultra-thin layer chromatography (UTLC) and surface enhanced Raman spectroscopy (SERS). The UTLC-SERS plate consists of an AgNR array fabricated by oblique angle deposition. The capability of the AgNR substrates to separate the different compounds in a mixture was explored using a mixture of four dyes and a mixture of melamine and Rhodamine 6G at varied concentrations with different mobile phase solvents. After UTLC separation, spatially-resolved SERS spectra were collected along the mobile phase development direction and the intensities of specific SERS peaks from each component were used to generate chromatograms. The AgNR substrates demonstrate the potential for separating the test dyes with plate heights as low as 9.6 μm. The limits of detection are between 10(-5)-10(-6) M. Furthermore, we show that the coupling of UTLC with SERS improves the SERS detection specificity, as small amounts of target analytes can be separated from the interfering background components.

  5. Mechanical properties of ultra-thin HfO2 films studied by nano scratches tests

    International Nuclear Information System (INIS)

    Fu, Wei-En; Chang, Yong-Qing; Chang, Chia-Wei; Yao, Chih-Kai; Liao, Jiunn-Der

    2013-01-01

    10-nm-thick atomic layer deposited HfO 2 films were characterized in terms of wear resistance and indentation hardness to investigate the thermal annealing induced impacts on mechanical properties. The wear resistance of ultra-thin films at low loads was characterized using nano-scratch tests with an atomic force microscope. The depth of the nano-scratches decreases with increasing annealing temperature, indicating that the hardness of the annealed films increases with the annealing temperatures. Surface nanoindentation was also performed to confirm the nanoscratch test results. The hardness variation of the annealed films is due to the generation of HfSi x O y induced by the thermal annealing. X-ray photoelectron spectroscopy measurements proved that the hardness of formed HfSi x O y with increasing annealing temperatures. The existence of HfSi x O y broadens the interface, and causes the increase of the interfacial layer thickness. As a result, the surface hardness increases with the increasing HfSi x O y induced by the thermal annealing. - Highlights: ► Mechanical properties of HfO 2 films were assessed by nano-scratch and indentation. ► Scratch depth of HfO 2 films decreased with the increase of annealing temperatures. ► Nano-hardness of HfO 2 films increased with the increase of annealing temperatures

  6. Ultra-thin Polyethylene glycol Coatings for Stem Cell Culture

    Science.gov (United States)

    Schmitt, Samantha K.

    Human mesenchymal stem cells (hMSCs) are a widely accessible and a clinically relevant cell type that are having a transformative impact on regenerative medicine. However, current clinical expansion methods can lead to selective changes in hMSC phenotype resulting from relatively undefined cell culture surfaces. Chemically defined synthetic surfaces can aid in understanding stem cell behavior. In particular we have developed chemically defined ultra-thin coatings that are stable over timeframes relevant to differentiation of hMSCs (several weeks). The approach employs synthesis of a copolymer with distinct chemistry in solution before application to a substrate. This provides wide compositional flexibility and allows for characterization of the orthogonal crosslinking and peptide binding groups. Characterization is done in solution by proton NMR and after crosslinking by X-ray photoelectron spectroscopy (XPS). The solubility of the copolymer in ethanol and low temperature crosslinking, expands its applicability to plastic substrates, in addition to silicon, glass, and gold. Cell adhesive peptides, namely Arg-Gly-Asp (RGD) fragments, are coupled to coating via different chemistries resulting in the urethane, amide or the thioester polymer-peptide bonds. Development of azlactone-based chemistry allowed for coupling in water at low peptide concentrations and resulted in either an amide or thioester bonds, depending on reactants. Characterization of the peptide functionalized coating by XPS, infrared spectroscopy and cell culture assays, showed that the amide linkages can present peptides for multiple weeks, while shorter-term presentation of a few days is possible using the more labile thioester bond. Regardless, coatings promoted initial adhesion and spreading of hMSCs in a peptide density dependent manner. These coatings address the following challenges in chemically defined cell culture simultaneously: (i) substrate adaptability, (ii) scalability over large areas

  7. Magnetic field induced superconductor-insulator transitions for ultra-thin Bi films on the different underlayers

    International Nuclear Information System (INIS)

    Makise, K; Kawaguti, T; Shinozaki, B

    2009-01-01

    This work shows the experimental results of the superconductor-insulator (S-I) transition for ultra-thin Bi films in magnetic fields. The quench-condensed (q-c) Bi film onto insulating underlayers have been interpreted to be homogeneous. In contrast, the Bi film without underlayers has been regarded as a granular film. The electrical transport properties of ultra-thin metal films near the S-I transition depend on the structure of the film. In order to confirm the effect of the underlayer to the homogeneity of the superconducting films, we investigate the characteristics of S-I transitions of q-c nominally homogeneous Bi films on underlayers of two insulating materials, SiO, and Sb. Under almost the same deposition condition except for the material of underlayer, we prepared the Bi films by repeating the additional deposition and performed in-situ electrical measurement. It is found that the transport properties near the S-I transitions show the remarkable difference between two films on different underlayers. As for Bi films on SiO, it turned out that the temperature dependence of resistance per square R sq (T) of the field-tuned transition and the thickness-tuned transition shows similar behavior; it was a thermally activated form. On the other hand, the R sq (T) of Bi films on Sb for thickness-tuned S-I transition showed logarithmic temperature dependence, but that for field-tuned S-I transition showed a thermally activated form.

  8. Ultra thin metallic coatings to control near field radiative heat transfer

    Science.gov (United States)

    Esquivel-Sirvent, R.

    2016-09-01

    We present a theoretical calculation of the changes in the near field radiative heat transfer between two surfaces due to the presence of ultra thin metallic coatings on semiconductors. Depending on the substrates, the radiative heat transfer is modulated by the thickness of the ultra thin film. In particular we consider gold thin films with thicknesses varying from 4 to 20 nm. The ultra-thin film has an insulator-conductor transition close to a critical thickness of dc = 6.4 nm and there is an increase in the near field spectral heat transfer just before the percolation transition. Depending on the substrates (Si or SiC) and the thickness of the metallic coatings we show how the near field heat transfer can be increased or decreased as a function of the metallic coating thickness. The calculations are based on available experimental data for the optical properties of ultrathin coatings.

  9. Film-thickness dependence of structure formation in ultra-thin polymer blend films

    CERN Document Server

    Gutmann, J S; Stamm, M

    2002-01-01

    We investigated the film-thickness dependence of structure formation in ultra-thin polymer blend films prepared from solution. As a model system we used binary blends of statistical poly(styrene-co-p-bromostyrene) copolymers of different degrees of bromination. Ultra-thin-film samples differing in miscibility and film thickness were prepared via spin coating of common toluene solutions onto silicon (100) substrates. The resulting morphologies were investigated with scanning force microscopy, reflectometry and grazing-incidence scattering techniques using both X-rays and neutrons in order to obtain a picture of the sample structure at and below the sample surface. (orig.)

  10. Analyzing nitrogen concentration using carrier illumination (CI) technology for DPN ultra-thin gate oxide

    International Nuclear Information System (INIS)

    Li, W.S.; Wu, Bill; Fan, Aki; Kuo, C.W.; Segovia, M.; Kek, H.A.

    2005-01-01

    Nitrogen concentration in the gate oxide plays a key role for 90 nm and below ULSI technology. Techniques like secondary ionization mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS) are commonly used for understanding N concentration. This paper describes the application of the carrier illuminationTM (CI) technique to measure the nitrogen concentration in ultra-thin gate oxides. A set of ultra-thin gate oxide wafers with different DPN (decoupled plasma nitridation) treatment conditions were measured using the CI technique. The CI signal has excellent correlation with the N concentration as measured by XPS

  11. Enhancement of absorption and color contrast in ultra-thin highly absorbing optical coatings

    Science.gov (United States)

    Kats, Mikhail A.; Byrnes, Steven J.; Blanchard, Romain; Kolle, Mathias; Genevet, Patrice; Aizenberg, Joanna; Capasso, Federico

    2013-09-01

    Recently a new class of optical interference coatings was introduced which comprises ultra-thin, highly absorbing dielectric layers on metal substrates. We show that these lossy coatings can be augmented by an additional transparent subwavelength layer. We fabricated a sample comprising a gold substrate, an ultra-thin film of germanium with a thickness gradient, and several alumina films. The experimental reflectivity spectra showed that the additional alumina layer increases the color range that can be obtained, in agreement with calculations. More generally, this transparent layer can be used to enhance optical absorption, protect against erosion, or as a transparent electrode for optoelectronic devices.

  12. Epitaxial growth of ultra-thin NbN films on AlxGa1−xN buffer-layers

    International Nuclear Information System (INIS)

    Krause, S; Meledin, D; Desmaris, V; Pavolotsky, A; Belitsky, V; Rudziński, M; Pippel, E

    2014-01-01

    The suitability of Al x Ga 1−x N epilayers to deposit onto ultra-thin NbN films has been demonstrated for the first time. High quality single-crystal films with 5 nm thickness confirmed by high resolution transmission electron microscopy (HRTEM) have been deposited in a reproducible manner by means of reactive DC magnetron sputtering at elevated temperatures and exhibit critical temperatures (T c ) as high as 13.2 K and residual resistivity ratio (RRR) ∼1 on hexagonal GaN epilayers. On increasing the Al content x in the Al x Ga 1−x N epilayer above 20%, a gradual deterioration of T c to 10 K was observed. Deposition of NbN on bare silicon substrates served as a reference and comparison. Excellent spatial homogeneity of the fabricated films was confirmed by R(T) measurements of patterned micro-bridges across the entire film area. The superconducting properties of these films were further characterized by critical magnetic field and critical current measurements. It is expected that the employment of GaN material as a buffer-layer for the deposition of ultra-thin NbN films will prospectively benefit terahertz electronics, particularly hot electron bolometer (HEB) mixers. (paper)

  13. Nanowire decorated, ultra-thin, single crystalline silicon for photovoltaic devices.

    Science.gov (United States)

    Aurang, Pantea; Turan, Rasit; Unalan, Husnu Emrah

    2017-10-06

    Reducing silicon (Si) wafer thickness in the photovoltaic industry has always been demanded for lowering the overall cost. Further benefits such as short collection lengths and improved open circuit voltages can also be achieved by Si thickness reduction. However, the problem with thin films is poor light absorption. One way to decrease optical losses in photovoltaic devices is to minimize the front side reflection. This approach can be applied to front contacted ultra-thin crystalline Si solar cells to increase the light absorption. In this work, homojunction solar cells were fabricated using ultra-thin and flexible single crystal Si wafers. A metal assisted chemical etching method was used for the nanowire (NW) texturization of ultra-thin Si wafers to compensate weak light absorption. A relative improvement of 56% in the reflectivity was observed for ultra-thin Si wafers with the thickness of 20 ± 0.2 μm upon NW texturization. NW length and top contact optimization resulted in a relative enhancement of 23% ± 5% in photovoltaic conversion efficiency.

  14. Finite Element Modelling of Bends and Creases during Folding Ultra Thin Stainless Steel Foils

    NARCIS (Netherlands)

    Datta, K.; Akagi, H.; Geijselaers, Hubertus J.M.; Huetink, Han

    2003-01-01

    Finite Element Modelling of an ultra thin foil of SUS 304 stainless steel is carried out. These foils are 20 mm and below in thickness. The development of stresses and strains during folding of these foils is studied. The objective of this study is to induce qualities of paper in the foils of

  15. How Do Organic Vapors Swell Ultra-Thin PIM-1 Films?

    KAUST Repository

    Ogieglo, Wojciech; Rahimi, Khosrow; Rauer, Sebastian Bernhard; Ghanem, Bader; Ma, Xiao-Hua; Pinnau, Ingo; Wessling, Matthias

    2017-01-01

    Dynamic sorption of ethanol and toluene vapor into ultra-thin supported PIM-1 films down to 6 nm are studied with a combination of in-situ spectroscopic ellipsometry and in-situ X-ray reflectivity. Both ethanol and toluene significantly swell

  16. Development and implementation of ultra-thin concrete road technology for suburban streets in South Africa

    CSIR Research Space (South Africa)

    Louw, MR

    2011-01-01

    Full Text Available Louw, FC Rust, AO Bergh and AH McKay DEVELOPMENT AND IMPLEMENTATIONN OF ULTRA- THIN CONCRETE ROAD TECHNOLOGY FOR SUBURBAN STREETS IN SOUTH AFRICA MR Louw, FC Rust, AO Bergh and AH McKay CSIR, Republic of South Africa rlouw...

  17. COVALENTLY ATTACHED MULTILAYER ULTRA-THIN FILMS FROM DIAZORESIN AND CALIXARENES

    Institute of Scientific and Technical Information of China (English)

    Zhao-hui Yang; Wei-xiao Cao

    2003-01-01

    A kind of photosensitive ultra-thin film was fabricated from diazoresin (DR) and various calixarenes by using the self-assembly technique. Under UV irradiation both the ionic- and hydrogen bonds between the layers of the film will convert into covalent bonds. As a result, the stability of the film toward polar solvents increases dramatically.

  18. Ultra-thin ZnSe: Anisotropic and flexible crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Bacaksiz, C., E-mail: cihanbacaksiz@iyte.edu.tr [Department of Physics, Izmir Institute of Technology, 35430 Izmir (Turkey); Senger, R.T. [Department of Physics, Izmir Institute of Technology, 35430 Izmir (Turkey); Sahin, H. [Department of Photonics, Izmir Institute of Technology, 35430 Izmir (Turkey)

    2017-07-01

    Highlights: • Ultra-thin ZnSe is dynamically stable. • Ultra-thin ZnSe is electronically direct-gap semiconductor. • Ultra-thin ZnSe is ultra-flexible. • Ultra-thin ZnSe is mechanically in-plane anisotropic. - Abstract: By performing density functional theory-based calculations, we investigate the structural, electronic, and mechanical properties of the thinnest ever ZnSe crystal . The vibrational spectrum analysis reveals that the monolayer ZnSe is dynamically stable and has flexible nature with its soft phonon modes. In addition, a direct electronic band gap is found at the gamma point for the monolayer structure of ZnSe. We also elucidate that the monolayer ZnSe has angle dependent in-plane elastic parameters. In particular, the in-plane stiffness values are found to be 2.07 and 6.89 N/m for the arm-chair and zig-zag directions, respectively. The angle dependency is also valid for the Poisson ratio of the monolayer ZnSe. More significantly, the in-plane stiffness of the monolayer ZnSe is the one-tenth of Young modulus of bulk zb-ZnSe which indicates that the monolayer ZnSe is a quite flexible single layer crystal. With its flexible nature and in-plane anisotropic mechanical properties, the monolayer ZnSe is a good candidate for nanoscale mechanical applications.

  19. Ultra-thin ZnSe: Anisotropic and flexible crystal structure

    International Nuclear Information System (INIS)

    Bacaksiz, C.; Senger, R.T.; Sahin, H.

    2017-01-01

    Highlights: • Ultra-thin ZnSe is dynamically stable. • Ultra-thin ZnSe is electronically direct-gap semiconductor. • Ultra-thin ZnSe is ultra-flexible. • Ultra-thin ZnSe is mechanically in-plane anisotropic. - Abstract: By performing density functional theory-based calculations, we investigate the structural, electronic, and mechanical properties of the thinnest ever ZnSe crystal . The vibrational spectrum analysis reveals that the monolayer ZnSe is dynamically stable and has flexible nature with its soft phonon modes. In addition, a direct electronic band gap is found at the gamma point for the monolayer structure of ZnSe. We also elucidate that the monolayer ZnSe has angle dependent in-plane elastic parameters. In particular, the in-plane stiffness values are found to be 2.07 and 6.89 N/m for the arm-chair and zig-zag directions, respectively. The angle dependency is also valid for the Poisson ratio of the monolayer ZnSe. More significantly, the in-plane stiffness of the monolayer ZnSe is the one-tenth of Young modulus of bulk zb-ZnSe which indicates that the monolayer ZnSe is a quite flexible single layer crystal. With its flexible nature and in-plane anisotropic mechanical properties, the monolayer ZnSe is a good candidate for nanoscale mechanical applications.

  20. Opto-electrical approaches for high efficiency and ultra-thin c-Si solar cells

    NARCIS (Netherlands)

    Ingenito, A.; Isabella, O.; Zeman, M.

    2014-01-01

    The need for cost reduction requires using less raw material and cost-effective processes without sacrificing the conversion efficiency. For keeping high the generated photo-current, an advanced light trapping scheme for ultra-thin silicon wafers is here proposed, exhibiting absorptances up to 99%

  1. Estimating the thickness of ultra thin sections for electron microscopy by image statistics

    DEFF Research Database (Denmark)

    Sporring, Jon; Khanmohammadi, Mahdieh; Darkner, Sune

    2014-01-01

    We propose a method for estimating the thickness of ultra thin histological sections by image statistics alone. Our method works for images, that are the realisations of a stationary and isotropic stochastic process, and it relies on the existence of statistical image-measures that are strictly m...

  2. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Prathap Pathi

    2017-01-01

    Full Text Available Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm and is slightly lower (by ~5% at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm silicon and just 1%–2% for thicker (>100 μm cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  3. Preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles and their application in hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Mahmoudian, M.R.; Alias, Y.; Basirun, W.J.; Ebadi, M.

    2012-01-01

    Highlights: ► Ag nanoparticles-decorated ultra thin polypyrrole nanosheets were prepared. ► Higher surface area of the polymer increased interaction between the polymer and Ag + . ► The sensitivity was estimated to be 4.477 μA mM −1 for linear segment. ► The LOD and LOQ (S/N = 3) were estimated to be 0.57 μM and 1.93 μM, respectively. - Abstract: This study examines the preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles (Ag-UTPNSs) and their application in the enzyme-less detection of hydrogen peroxide (H 2 O 2 ) detection. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirmed that Ag nanoparticles (NPs) were deposited onto the surface of the UTPNSs. The increase of the H 2 O 2 reduction current peak to 120 μA in the presence of the Ag-UTPNS/glassy carbon electrode (GCE) as compared to the UTPNS/GCE indicates that the sensitivity of the electrode to H 2 O 2 is significant. This observation can be explained by the larger surface area of the UTPNSs, which can increase the interactions between the polymer and the AgNO 3 solution during the deposition of the Ag NPs, and by the small size of the deposited Ag NPs, which can produce a surface area of Ag that is suitable for the reaction with H 2 O 2 . The amperometric responses show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated to be 0.57 μM, 1.93 μM and 4.477 μA mM −1 , respectively, for the linear segment. The results of the reproducibility experiments show that the use of Ag-UTPNS/GCE is feasible for the quantitative detection of certain concentration ranges of H 2 O 2 .

  4. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    International Nuclear Information System (INIS)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman

    2016-01-01

    Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatch between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or

  5. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman, E-mail: anis@eee.buet.ac.bd [Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka 1205 (Bangladesh)

    2016-05-21

    Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatch between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are square or

  6. Ultra-thin lithium micro-batteries. Performances and applications; Microaccumulateurs ultra minces au lithium. Performances et applications

    Energy Technology Data Exchange (ETDEWEB)

    Martin, M.; Terrat, J.P. [Hydromecanique et frottement (HEF), 42 - Andrezieux Boutheon (France); Levasseur, A.; Vinatier, P.; Meunier, G. [Centre National de la Recherche Scientifique (CNRS), 33 - Talence (France). Institut de Chimie de la Matiere Condensee et Physique de Bordeaux

    1996-12-31

    This short paper (abstract) describes the characteristics and performances of prototypes of ultra-thin lithium micro-batteries (thickness < 0.2 mm) which can be incorporated into microelectronic circuits. (J.S.)

  7. Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

    KAUST Repository

    Yave, Wilfredo; Car, Anja; Wind, Jan; Peinemann, Klaus Viktor

    2010-01-01

    Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform

  8. Ultra-thin lithium micro-batteries. Performances and applications; Microaccumulateurs ultra minces au lithium. Performances et applications

    Energy Technology Data Exchange (ETDEWEB)

    Martin, M; Terrat, J P [Hydromecanique et frottement (HEF), 42 - Andrezieux Boutheon (France); Levasseur, A; Vinatier, P; Meunier, G [Centre National de la Recherche Scientifique (CNRS), 33 - Talence (France). Institut de Chimie de la Matiere Condensee et Physique de Bordeaux

    1997-12-31

    This short paper (abstract) describes the characteristics and performances of prototypes of ultra-thin lithium micro-batteries (thickness < 0.2 mm) which can be incorporated into microelectronic circuits. (J.S.)

  9. Ultra-thin flexible polyimide neural probe embedded in a dissolvable maltose-coated microneedle

    International Nuclear Information System (INIS)

    Xiang, Zhuolin; Yen, Shih-Cheng; Zhang, Songsong; Lee, Chengkuo; Xue, Ning; Sun, Tao; Tsang, Wei Mong; Liao, Lun-De; Thakor, Nitish V

    2014-01-01

    The ultra-thin flexible polyimide neural probe can reduce the glial sheath growth on the probe body while its flexibility can minimize the micromotion between the probe and brain tissue. To provide sufficient stiffness for penetration purposes, we developed a drawing lithography technology for uniform maltose coating to make the maltose-coated polyimide neural probe become a stiff microneedle. The coating thicknesses under different temperature and the corresponding stiffness are studied. It has been proven that the coated maltose is dissolved by body fluids after implantation for a few seconds. Moreover, carbon nanotubes are coated on the neural probe recording electrodes to improve the charge delivery ability and reduce the impedance. Last but not least, the feasibility and recording characteristic of this ultra-thin polyimide neural probe embedded in a maltose-coated microneedle are further demonstrated by in vivo tests. (paper)

  10. Ultra-thin flexible polyimide neural probe embedded in a dissolvable maltose-coated microneedle

    Science.gov (United States)

    Xiang, Zhuolin; Yen, Shih-Cheng; Xue, Ning; Sun, Tao; Mong Tsang, Wei; Zhang, Songsong; Liao, Lun-De; Thakor, Nitish V.; Lee, Chengkuo

    2014-06-01

    The ultra-thin flexible polyimide neural probe can reduce the glial sheath growth on the probe body while its flexibility can minimize the micromotion between the probe and brain tissue. To provide sufficient stiffness for penetration purposes, we developed a drawing lithography technology for uniform maltose coating to make the maltose-coated polyimide neural probe become a stiff microneedle. The coating thicknesses under different temperature and the corresponding stiffness are studied. It has been proven that the coated maltose is dissolved by body fluids after implantation for a few seconds. Moreover, carbon nanotubes are coated on the neural probe recording electrodes to improve the charge delivery ability and reduce the impedance. Last but not least, the feasibility and recording characteristic of this ultra-thin polyimide neural probe embedded in a maltose-coated microneedle are further demonstrated by in vivo tests.

  11. Field emission mechanism from a single-layer ultra-thin semiconductor film cathode

    International Nuclear Information System (INIS)

    Duan Zhiqiang; Wang Ruzhi; Yuan Ruiyang; Yang Wei; Wang Bo; Yan Hui

    2007-01-01

    Field emission (FE) from a single-layer ultra-thin semiconductor film cathode (SUSC) on a metal substrate has been investigated theoretically. The self-consistent quantum FE model is developed by synthetically considering the energy band bending and electron scattering. As a typical example, we calculate the FE properties of ultra-thin AlN film with an adjustable film thickness from 1 to 10 nm. The calculated results show that the FE characteristic is evidently modulated by varying the film thickness, and there is an optimum thickness of about 3 nm. Furthermore, a four-step FE mechanism is suggested such that the distinct FE current of a SUSC is rooted in the thickness sensitivity of its quantum structure, and the optimum FE properties of the SUSC should be attributed to the change in the effective potential combined with the attenuation of electron scattering

  12. Lithium battery electrodes with ultra-thin alumina coatings

    Science.gov (United States)

    Se-Hee, Lee; George, Steven M.; Cavanagh, Andrew S.; Yoon Seok, Jung; Dillon, Anne C.

    2015-11-24

    Electrodes for lithium batteries are coated via an atomic layer deposition process. The coatings can be applied to the assembled electrodes, or in some cases to particles of electrode material prior to assembling the particles into an electrode. The coatings can be as thin as 2 .ANG.ngstroms thick. The coating provides for a stable electrode. Batteries containing the electrodes tend to exhibit high cycling capacities.

  13. Structural studies on Langmuir-Blodgett ultra-thin films on tin (IV) stearate using X-ray diffraction technique

    International Nuclear Information System (INIS)

    Mohamad Deraman; Muhamad Mat Salleh; Mohd Ali Sulaiman; Mohd Ali Sufi

    1991-01-01

    X-ray diffraction measurements were carried out on Langmuir-Blodgett (LB) ultra-thin films of tin (IV) stearate for different numbers of layers. The structural information such as interplanar spacing, unit cells spacing, molecular length and orientation of molecular chains were obtained from the diffraction data. This information is discussed and compared with that previously published for LB ultra-thin films of manganese stearate and cadmium stearate

  14. Determining surface coverage of ultra-thin gold films from X-ray reflectivity measurements

    International Nuclear Information System (INIS)

    Kossoy, A.; Simakov, D.; Olafsson, S.; Leosson, K.

    2013-01-01

    The paper describes usage of X-ray reflectivity for characterization of surface coverage (i.e. film continuity) of ultra-thin gold films which are widely studied for optical, plasmonic and electronic applications. The demonstrated method is very sensitive and can be applied for layers below 1 nm. It has several advantages over other techniques which are often employed in characterization of ultra-thin metal films, such as optical absorption, Atomic Force Microscopy, Transmission Electron Microscopy or Scanning Electron Microscopy. In contrast to those techniques our method does not require specialized sample preparation and measurement process is insensitive to electrostatic charge and/or presence of surface absorbed water. We validate our results with image processing of Scanning Electron Microscopy images. To ensure precise quantitative analysis of the images we developed a generic local thresholding algorithm which allowed us to treat series of images with various values of surface coverage with similar image processing parameters. - Highlights: • Surface coverage/continuity of ultra-thin Au films (up to 7 nm) was determined. • Results from X-ray reflectivity were verified by scanning electron microscopy. • We developed local thresholding algorithm to treat non-homogeneous image contrast

  15. Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes.

    Science.gov (United States)

    Gu, Yu; Wang, Wei-Wei; Li, Yi-Juan; Wu, Qi-Hui; Tang, Shuai; Yan, Jia-Wei; Zheng, Ming-Sen; Wu, De-Yin; Fan, Chun-Hai; Hu, Wei-Qiang; Chen, Zhao-Bin; Fang, Yuan; Zhang, Qing-Hong; Dong, Quan-Feng; Mao, Bing-Wei

    2018-04-09

    Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity. The polished metal anodes exhibit significantly enhanced cycling stability, specifically the lithium anodes can cycle for over 200 times at a real current density of 2 mA cm -2 with 100% depth of discharge. Our work illustrates that an ultra-smooth ultra-thin solid-electrolyte interphase may be robust enough to suppress dendrite growth and thus serve as an initial layer for further improved protection of alkali metal anodes.

  16. Research on precision grinding technology of large scale and ultra thin optics

    Science.gov (United States)

    Zhou, Lian; Wei, Qiancai; Li, Jie; Chen, Xianhua; Zhang, Qinghua

    2018-03-01

    The flatness and parallelism error of large scale and ultra thin optics have an important influence on the subsequent polishing efficiency and accuracy. In order to realize the high precision grinding of those ductile elements, the low deformation vacuum chuck was designed first, which was used for clamping the optics with high supporting rigidity in the full aperture. Then the optics was planar grinded under vacuum adsorption. After machining, the vacuum system was turned off. The form error of optics was on-machine measured using displacement sensor after elastic restitution. The flatness would be convergenced with high accuracy by compensation machining, whose trajectories were integrated with the measurement result. For purpose of getting high parallelism, the optics was turned over and compensation grinded using the form error of vacuum chuck. Finally, the grinding experiment of large scale and ultra thin fused silica optics with aperture of 430mm×430mm×10mm was performed. The best P-V flatness of optics was below 3 μm, and parallelism was below 3 ″. This machining technique has applied in batch grinding of large scale and ultra thin optics.

  17. Low-temperature transport in ultra-thin tungsten films

    Energy Technology Data Exchange (ETDEWEB)

    Chiatti, Olivio [Neue Materialien, Institut fuer Physik, Humboldt-Univ. Berlin (Germany); London Centre for Nanotechnology, University College London (United Kingdom); Nash, Christopher; Warburton, Paul [London Centre for Nanotechnology, University College London (United Kingdom)

    2012-07-01

    Tungsten-containing films, fabricated by focused-ion-beam-induced chemical vapour deposition, are known to have an enhanced superconducting transition temperature compared to bulk tungsten, and have been investigated previously for film thickness down to 25 nm. In this work, by using ion-beam doses below 50 pC/{mu}m{sup 2} on a substrate of amorphous silicon, we have grown continuous films with thickness below 20 nm. The electron transport properties were investigated at temperatures down to 350 mK and in magnetic fields up to 3 T, parallel and perpendicular to the films. The films in this work are closer to the limit of two-dimensional systems and are superconducting at low temperatures. Magnetoresistance measurements yield upper critical fields of the order of 1 T, and the resulting coherence length is smaller than the film thickness.

  18. Electron transport determines the electrochemical properties of tetrahedral amorphous carbon (ta-C) thin films

    International Nuclear Information System (INIS)

    Palomäki, Tommi; Wester, Niklas; Caro, Miguel A.; Sainio, Sami; Protopopova, Vera; Koskinen, Jari; Laurila, Tomi

    2017-01-01

    Amorphous carbon based electrodes are very promising for electrochemical sensing applications. In order to better understand their structure-function relationship, the effect of film thickness on the electrochemical properties of tetrahedral amorphous carbon (ta-C) electrodes was investigated. ta-C thin films of 7, 15, 30, 50 and 100 nm were characterized in detail with Raman spectroscopy, transmission electron microscopy (TEM), conductive atomic force microscopy (c-AFM), scanning tunneling spectroscopy (STS) and X-ray absorption spectroscopy (XAS) to assess (i) the surface properties of the films, (ii) the effect of film thickness on their structure and electrical properties and (iii) the subsequent correlation with their electrochemistry. The electrochemical properties were investigated by cyclic voltammetry (CV) using two different outer-sphere redox probes, Ru(NH 3 ) 6 3+/2+ and FcMeOH, and by electrochemical impedance spectroscopy (EIS). Computational simulations using density functional theory (DFT) were carried out to rationalize the experimental findings. The characterization results showed that the sp 2 /sp 3 ratio increased with decreasing ta-C film thickness. This correlated with a decrease in mobility gap value and an increase in the average current through the films, which was also consistent with the computational results. XAS indicated that the surface of the ta-C films was always identical and composed of a sp 2 -rich layer. The CV measurements indicated reversible reaction kinetics for both outer-sphere redox probes at 7 and 15 nm ta-C films with a change to quasi-reversible behavior at a thickness of around 30 nm. The charge transfer resistance, obtained from EIS measurements, decreased with decreasing film thickness in accordance with the CV results. Based on the characterization and electrochemical results, we conclude that the reaction kinetics in the case of outer-sphere redox systems is determined mainly by the electron transport through the

  19. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    International Nuclear Information System (INIS)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong; Ma, Zhongquan

    2016-01-01

    Highlights: • A new kind of functional material with plasticity of dielectric was obtained. • Powerful characterization methods was exploited to determine this ultra-thin layer. • The electronic structures and properties of this intermediate layer were analyzed. • A potential application of this structure were investigated. - Abstract: A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  20. Young's Modulus and Coefficient of Linear Thermal Expansion of ZnO Conductive and Transparent Ultra-Thin Films

    Directory of Open Access Journals (Sweden)

    Naoki Yamamoto

    2011-01-01

    Full Text Available A new technique for measuring Young's modulus of an ultra-thin film, with a thickness in the range of about 10 nm, was developed by combining an optical lever technique for measuring the residual stress and X-ray diffraction for measuring the strain in the film. The new technique was applied to analyze the mechanical properties of Ga-doped ZnO (GZO films, that have become the focus of significant attention as a substitute material for indium-tin-oxide transparent electrodes. Young's modulus of the as-deposited GZO films decreased with thickness; the values for 30 nm and 500 nm thick films were 205 GPa and 117 GPa, respectively. The coefficient of linear thermal expansion of the GZO films was measured using the new technique in combination with in-situ residual stress measurement during heat-cycle testing. GZO films with 30–100 nm thickness had a coefficient of linear thermal expansion in the range of 4.3 × 10−6 – 5.6 × 10−6 °C−1.

  1. Thin layer activation and ultra thin layer activation: two complementary techniques for wear and corrosion studies in various fields

    International Nuclear Information System (INIS)

    Sauvage, T.; Vincent, L.; Blondiaux, G.

    2002-01-01

    Thin layer activation (TLA) is widely used since more than 25 years to study surface wear or corrosion. This well known technique uses most of the time charged particles activation, which gives sensitivity in the range of the micrometer, except when the fluid mode of detection is utilized. In this case application of the method is limited to phenomena where we have transport of radioactive fragments to detection point. The main disadvantage of this procedure is the error due to trapping phenomena between the wear or corrosion point and detection setup. So the ultra thin layer activation (UTLA) has been developed to get nanometric sensitivity without using any fluid for radioactivity transportation, which is the main source of error of the TLA technique. In this paper we shall briefly describe the TLA technique and the most important fields of application. Then we shall emphasise on UTLA with a presentation of the principle of the method and actual running of application. The main problem concerning UTLA is calibration which requires the use of thin films (usually 10 to 100 nanometers) deposited on substrate. This process is time consuming and we shall demonstrate how running software developed in the lab can solve it. We shall finish the presentation by giving some potential application of the technique in various fields. (authors)

  2. Mechanical properties of ultra-thin HfO{sub 2} films studied by nano scratches tests

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wei-En; Chang, Yong-Qing [Center for Measurement Standards, Industrial Technology Research Institute, Room 216, Building 8, 321, Kuang Fu Road Sec. 2, Hsinchu, Taiwan (China); Chang, Chia-Wei; Yao, Chih-Kai [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Jiunn-Der, E-mail: jdliao@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2013-02-01

    10-nm-thick atomic layer deposited HfO{sub 2} films were characterized in terms of wear resistance and indentation hardness to investigate the thermal annealing induced impacts on mechanical properties. The wear resistance of ultra-thin films at low loads was characterized using nano-scratch tests with an atomic force microscope. The depth of the nano-scratches decreases with increasing annealing temperature, indicating that the hardness of the annealed films increases with the annealing temperatures. Surface nanoindentation was also performed to confirm the nanoscratch test results. The hardness variation of the annealed films is due to the generation of HfSi{sub x}O{sub y} induced by the thermal annealing. X-ray photoelectron spectroscopy measurements proved that the hardness of formed HfSi{sub x}O{sub y} with increasing annealing temperatures. The existence of HfSi{sub x}O{sub y} broadens the interface, and causes the increase of the interfacial layer thickness. As a result, the surface hardness increases with the increasing HfSi{sub x}O{sub y} induced by the thermal annealing. - Highlights: ► Mechanical properties of HfO{sub 2} films were assessed by nano-scratch and indentation. ► Scratch depth of HfO{sub 2} films decreased with the increase of annealing temperatures. ► Nano-hardness of HfO{sub 2} films increased with the increase of annealing temperatures.

  3. Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong [SHU-SolarE R& D Lab, Department of Physics, Shanghai University, Shanghai 200444 (China); Ma, Zhongquan, E-mail: zqma@shu.edu.cn [SHU-SolarE R& D Lab, Department of Physics, Shanghai University, Shanghai 200444 (China); Instrumental Analysis & Research Center, Shanghai University, Shanghai 200444 (China)

    2016-12-01

    Highlights: • A new kind of functional material with plasticity of dielectric was obtained. • Powerful characterization methods was exploited to determine this ultra-thin layer. • The electronic structures and properties of this intermediate layer were analyzed. • A potential application of this structure were investigated. - Abstract: A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

  4. Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

    Science.gov (United States)

    Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

    2016-05-01

    Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V-1 sec-1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process.

  5. Influence of additions of nanoparticles TaC on a microstructure laser cladding

    International Nuclear Information System (INIS)

    Murzakov, M A; Petrovskiy, V N; Polski, V I; Mironov, V D; Prokopova, N M; Tret'yakov, E V

    2015-01-01

    The features of a laser cladding of nickel-based powders with TaC nanopowder additives have been experimentally investigated. The minimum depth of pro-melting of a basis, microhardness distribution over the cross section of the substrate, and the saturation of the metal of the cladding with basis components has been determined in the experiments

  6. Ultra-thin Oxide Membranes: Synthesis and Carrier Transport

    Science.gov (United States)

    Sim, Jai Sung

    Self-supported freestanding membranes are films that are devoid of any underlying supporting layers. The key advantage of such structures is that, due to the lack of substrate effects - both mechanical and chemical, the true native properties of the material can be probed. This is crucial since many of the studies done on materials that are used as freestanding membranes are done as films clamped to substrates or in the bulk form. This thesis focuses on the synthesis and fabrication as well as electrical studies of free standing ultrathin controllable thin film deposition process. Taking things a step further, to electrically probe these membranes required design of complex device architecture and extensive optimization of nano-fabrication processes. The challenges and optimized fabrication method of such membranes are demonstrated. Three materials are probed in this study, VO2, TiO2, and CeO2. VO2 for understanding structural considerations for electronic phase change and nature of ionic liquid gating, TiO2 and CeO2 for understanding surface conduction properties and surface chemistry. The VO2 study shows shift in metal-insulator transition (MIT) temperature arising from stress relaxation and opening of the hysteresis. The ionic liquid gating studies showed reversible modulation of channel resistance and allowed distinguishing bulk process from the surface effects. Comparing the ionic liquid gating experiments to hydrogen doping experiments illustrated that ionic liquid gating can be a surface limited electrostatic effect, if the critical voltage threshold is not exceeded. TiO2 study shows creation of non-stoichiometric forms under ion milling. Utilizing focused ion beam milling, thin membranes of Ti xOy of 100-300 nm thickness have been created. TEM studies indicated polycrystallinity and presence of twins in the FIB-milled nanowalls. Compositional analysis in the transmission electron microscope also showed reduced content of oxygen, confirming non

  7. Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Paul M., E-mail: paul.dietrich@yahoo.de [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Glamsch, Stephan [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Freie Universität Berlin, Institut für Chemie und Biochemie, Fabeckstr. 34/36, 14195 Berlin (Germany); Ehlert, Christopher [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam (Germany); Lippitz, Andreas [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany); Kulak, Nora [Freie Universität Berlin, Institut für Chemie und Biochemie, Fabeckstr. 34/36, 14195 Berlin (Germany); Unger, Wolfgang E.S. [Bundesanstalt für Materialforschung und – prüfung (BAM), Unter den Eichen 87, 12205 Berlin (Germany)

    2016-02-15

    Graphical abstract: - Highlights: • A synchrotron-based XPS method to analyze ultra-thin silane films is presented. • Specification and quantification of organic next to inorganic silicon is demonstrated. • Non-destructive chemical depth profiles of the silane monolayers were obtained. - Abstract: The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z{sub 95} of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) – inorganic (SiO{sub 2}/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS.

  8. Ultra-thin smart acoustic metasurface for low-frequency sound insulation

    Science.gov (United States)

    Zhang, Hao; Xiao, Yong; Wen, Jihong; Yu, Dianlong; Wen, Xisen

    2016-04-01

    Insulating low-frequency sound is a conventional challenge due to the high areal mass required by mass law. In this letter, we propose a smart acoustic metasurface consisting of an ultra-thin aluminum foil bonded with piezoelectric resonators. Numerical and experimental results show that the metasurface can break the conventional mass law of sound insulation by 30 dB in the low frequency regime (sound insulation performance is attributed to the infinite effective dynamic mass density produced by the smart resonators. It is also demonstrated that the excellent sound insulation property can be conveniently tuned by simply adjusting the external circuits instead of modifying the structure of the metasurface.

  9. Role of interlayer coupling in ultra thin MoS2

    KAUST Repository

    Cheng, Yingchun

    2012-01-01

    The effects of interlayer coupling on the vibrational and electronic properties of ultra thin MoS 2 were studied by ab initio calculations. For smaller slab thickness, the interlayer distance is significantly elongated because of reduced interlayer coupling. This explains the anomalous thickness dependence of the lattice vibrations observed by Lee et al. (ACS Nano, 2010, 4, 2695). The absence of interlayer coupling in mono-layer MoS 2 induces a transition from direct to indirect band gap behaviour. Our results demonstrate a strong interplay between the intralayer chemical bonding and the interlayer van-der-Waals interaction. This journal is © 2012 The Royal Society of Chemistry.

  10. Growth and hydrogenation of ultra-thin Mg films on Mo(111)

    DEFF Research Database (Denmark)

    Ostenfeld, Christopher Worsøe; Davies, Jonathan Conrad; Vegge, Tejs

    2005-01-01

    . Hydrogen cannot be adsorbed on magnesium films under UHV conditions. However, when evaporating Mg in a hydrogen background, a hydrogen overlayer is seen to adsorb at the Mg surface, due to the catalytic interaction with the Mo(1 1 1) substrate and subsequent spill-over. We show that two monolayers of Mg......The growth and hydrogenation of ultra-thin magnesium overlayers have been investigated on a Mo(1 1 1) single crystal substrate. For increasing magnesium coverages we observe intermediate stages in the TPD and LEISS profiles, which illustrate the transition from one monolayer to multilayer growth...

  11. Electrical properties of single crystal Yttrium Iron Garnet ultra-thin films at high temperatures

    OpenAIRE

    Thiery, Nicolas; Naletov, Vladimir V.; Vila, Laurent; Marty, Alain; Brenac, Ariel; Jacquot, Jean-François; de Loubens, Grégoire; Viret, Michel; Anane, Abdelmadjid; Cros, Vincent; Youssef, Jamal Ben; Demidov, Vladislav E.; Demokritov, Sergej O.; Klein, Olivier

    2017-01-01

    We report a study on the electrical properties of 19 nm thick Yttrium Iron Garnet (YIG) films grown by liquid phase epitaxy. The electrical conductivity and Hall coefficient are measured in the high temperature range [300,400]~K using a Van der Pauw four-point probe technique. We find that the electrical resistivity decreases exponentially with increasing temperature following an activated behavior corresponding to a band-gap of $E_g\\approx 2$ eV, indicating that epitaxial YIG ultra-thin film...

  12. Fabrication and stability investigation of ultra-thin transparent and flexible Cu-Ag-Au tri-layer film on PET

    Science.gov (United States)

    Prakasarao, Ch Surya; D'souza, Slavia Deeksha; Hazarika, Pratim; Karthiselva N., S.; Ramesh Babu, R.; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul

    2018-04-01

    The need for transparent conducting electrodes with high transmittance, low sheet resistance and flexibility to replace Indium Tin Oxide is ever growing. We have deposited and studied the performance of ultra-thin Cu-Ag-Au tri-layer films over a flexible poly-ethylene terephthalate substrate. Scotch tape test showed good adhesion of the metallic film. Transmittance of the tri-layer was around 40 % in visible region. Optical profiler measurements were done to study the surface features. The XRD pattern revealed that film was amorphous. Sheet resistance measured by four probe technique was around 7.7 Ohm/Δ and was stable up to 423 K. The transport parameters by Hall effect showed high conductivity and carrier concentration with a mobility of 5.58 cm2/Vs. Tests performed in an indigenously designed bending unit indicated the films to be stable both mechanically and electrically even after 50,000 bending cycles.

  13. Effect of TaC addition on the microstructures and mechanical properties of Ti(C, N)-based cermets

    International Nuclear Information System (INIS)

    Wu, Peng; Zheng, Yong; Zhao, Yongle; Yu, Haizhou

    2010-01-01

    The microstructures of the prepared Ti(C, N)-based cermets with various TaC additions were studied using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Mechanical properties such as transverse rupture strength (TRS), fracture toughness (K 1C ) and hardness (HRA) were also measured. The results showed that the grain size of the cermets decreased with increasing TaC addition, but too high TaC addition resulted in agglomeration of the grains. An increasing TaC addition increased the dissolution of tungsten, titanium, molybdenum and tantalum in the binder phase. The hardness of the cermets decreased slightly with increasing TaC addition. The transverse rupture strength was the highest for the cermets with 5 wt.% TaC addition, which was characterized by fine grains, homogeneous microstructure and the moderate thickness of rim phase in the binder. The fracture toughness of the cermets with TaC addition from 0 to 5 wt.% decreased obviously, which resulting from decreased grain size. The further decreasing of fracture toughness for the cermets with 7 wt.% TaC addition was due to increased porosity and interfacial tensile stress.

  14. Controllable growth of stable germanium dioxide ultra-thin layer by means of capacitively driven radio frequency discharge

    Energy Technology Data Exchange (ETDEWEB)

    Svarnas, P., E-mail: svarnas@ece.upatras.gr [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26 504, Patras (Greece); Botzakaki, M.A. [Department of Physics, University of Patras, Rion 26 504 (Greece); Skoulatakis, G.; Kennou, S.; Ladas, S. [Surface Science Laboratory, Department of Chemical Engineering, University of Patras, Rion 26 504 (Greece); Tsamis, C. [NCSR “Demokritos”, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology & Microsystems, Aghia Paraskevi 15 310, Athens (Greece); Georga, S.N.; Krontiras, C.A. [Department of Physics, University of Patras, Rion 26 504 (Greece)

    2016-01-29

    It is well recognized that native oxide of germanium is hygroscopic and water soluble, while germanium dioxide is thermally unstable and it is converted to volatile germanium oxide at approximately 400 °C. Different techniques, implementing quite complicated plasma setups, gas mixtures and substrate heating, have been used in order to grow a stable germanium oxide. In the present work a traditional “RF diode” is used for germanium oxidation by cold plasma. Following growth, X-ray photoelectron spectroscopy demonstrates that traditional capacitively driven radio frequency discharges, using molecular oxygen as sole feedstock gas, provide the possibility of germanium dioxide layer growth in a fully reproducible and controllable manner. Post treatment ex-situ analyses on day-scale periods disclose the stability of germanium oxide at room ambient conditions, offering thus the ability to grow (ex-situ) ultra-thin high-k dielectrics on top of germanium oxide layers. Atomic force microscopy excludes any morphological modification in respect to the bare germanium surface. These results suggest a simple method for a controllable and stable germanium oxide growth, and contribute to the challenge to switch to high-k dielectrics as gate insulators for high-performance metal-oxide-semiconductor field-effect transistors and to exploit in large scale the superior properties of germanium as an alternative channel material in future technology nodes. - Highlights: • Simple one-frequency reactive ion etcher develops GeO{sub 2} thin layers controllably. • The layers remain chemically stable at ambient conditions over day-scale periods. • The layers are unaffected by the ex-situ deposition of high-k dielectrics onto them. • GeO{sub 2} oxidation and high-k deposition don't affect the Ge morphology significantly. • These conditions contribute to improved Ge-based MOS structure fabrication.

  15. Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells.

    Science.gov (United States)

    Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

    2014-10-01

    Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se 2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF 2 coated with a thin atomic layer deposited Al 2 O 3 layer, or direct current magnetron sputtering of Al 2 O 3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al 2 O 3 /CIGS rear interface. (MgF 2 /)Al 2 O 3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells.

  16. Employing Si solar cell technology to increase efficiency of ultra-thin Cu(In,Ga)Se2 solar cells

    Science.gov (United States)

    Vermang, Bart; Wätjen, Jörn Timo; Fjällström, Viktor; Rostvall, Fredrik; Edoff, Marika; Kotipalli, Ratan; Henry, Frederic; Flandre, Denis

    2014-01-01

    Reducing absorber layer thickness below 500 nm in regular Cu(In,Ga)Se2 (CIGS) solar cells decreases cell efficiency considerably, as both short-circuit current and open-circuit voltage are reduced because of incomplete absorption and high Mo/CIGS rear interface recombination. In this work, an innovative rear cell design is developed to avoid both effects: a highly reflective rear surface passivation layer with nano-sized local point contact openings is employed to enhance rear internal reflection and decrease the rear surface recombination velocity significantly, as compared with a standard Mo/CIGS rear interface. The formation of nano-sphere shaped precipitates in chemical bath deposition of CdS is used to generate nano-sized point contact openings. Evaporation of MgF2 coated with a thin atomic layer deposited Al2O3 layer, or direct current magnetron sputtering of Al2O3 are used as rear surface passivation layers. Rear internal reflection is enhanced substantially by the increased thickness of the passivation layer, and also the rear surface recombination velocity is reduced at the Al2O3/CIGS rear interface. (MgF2/)Al2O3 rear surface passivated ultra-thin CIGS solar cells are fabricated, showing an increase in short circuit current and open circuit voltage compared to unpassivated reference cells with equivalent CIGS thickness. Accordingly, average solar cell efficiencies of 13.5% are realized for 385 nm thick CIGS absorber layers, compared with 9.1% efficiency for the corresponding unpassivated reference cells. PMID:26300619

  17. Low temperature synthesis of Mo2C/W2C superlattices via ultra-thin modulated reactants

    International Nuclear Information System (INIS)

    Johnson, C.D.; Johnson, D.C.

    1996-01-01

    The authors report here a synthesis method of preparing carbide superlattices using ultra-thin modulated reactants. Initial investigations into the synthesis of the binary systems, Mo 2 C and W 2 C using ultra-thin modulated reactants revealed that both can be formed at relatively low temperatures (500 and 600 C respectively). DSC and XRD data suggested a two step reaction pathway involving interdiffusion of the initial modulated reactant followed by crystallization of the final product, if the modulation length is on the order of 10 angstrom. This information was used to form Mo 2 C/W 2 C superlattices using the structure of the ultra-thin modulated reactant to control the final superlattice period. Relatively large superlattice modulations were kinetically trapped by having several repeat units of each binary within the total repeat of the initial reactant. DSC and XRD data again are consistent with a two step reaction pathway leading to the formation of carbide superlattices

  18. GaAs detectors with an ultra-thin Schottky contact for spectrometry of charged particles

    Energy Technology Data Exchange (ETDEWEB)

    Chernykh, S.V., E-mail: chsv_84@mail.ru [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Chernykh, A.V. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Didenko, S.I.; Baryshnikov, F.M. [National University of Science and Technology “MISIS”, Moscow (Russian Federation); Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Burtebayev, N. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan); Britvich, G.I. [Institute of High Energy Physics, Protvino, Moscow region (Russian Federation); Chubenko, A.P. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow (Russian Federation); Guly, V.G.; Glybin, Yu.N. [LLC “SNIIP Plus”, Moscow (Russian Federation); Zholdybayev, T.K.; Burtebayeva, J.T.; Nassurlla, M. [Research Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Institute of Nuclear Physics, Almaty (Kazakhstan)

    2017-02-11

    For the first time, samples of particle detectors based on high-purity GaAs epilayers with an active area of 25 and 80 mm{sup 2} and an ultra-thin Pt Schottky barrier were fabricated for use in the spectrometry of charged particles and their operating characteristics were studied. The obtained FWHM of 14.2 (for 25 mm{sup 2} detector) and 15.5 keV (for 80 mm{sup 2} detector) on the 5.499 MeV line of {sup 238}Pu is at the level of silicon spectrometric detectors. It was found that the main component that determines the energy resolution of the detector is a fluctuation in the number of collected electron–hole pairs. This allows us to state that the obtained energy resolution is close to the limit for VPE GaAs. - Highlights: • VPE GaAs particle detectors with an active area of 25 and 80 mm{sup 2} were fabricated. • 120 Å ultra-thin Pt Schottky barrier was used as a rectifying contact. • The obtained FWHM of 14.2 keV ({sup 238}Pu) is at the level of Si spectrometric detectors. • Various components of the total energy resolution were analyzed. • It was shown that obtained energy resolution is close to its limit for VPE GaAs.

  19. Mixed-Penetrant Sorption in Ultra-Thin Films of Polymer of Intrinsic Microporosity PIM-1

    KAUST Repository

    Ogieglo, Wojciech; Furchner, Andreas; Ghanem, Bader; Ma, Xiao-Hua; Pinnau, Ingo; Wessling, Matthias

    2017-01-01

    Mixed penetrant sorption into ultra-thin films of a super-glassy polymer of intrinsic microporosity (PIM-1) was studied for the first time by using interference-enhanced in-situ spectroscopic ellipsometry. PIM-1 swelling and the concurrent changes in its refractive index were determined in ultra-thin (12 - 14 nm) films exposed to pure and mixed penetrants. The penetrants included water, n-hexane and ethanol and were chosen based on their significantly different penetrant-penetrant and penetrant-polymer affinities. This allowed studying microporous polymer responses at diverse ternary compositions and revealed effects such as competition for the sorption sites (for water / n-hexane or ethanol / n-hexane) or enhancement in sorption of typically weakly sorbing water in the presence of more highly sorbing ethanol. The results reveal details of the mutual sorption effects which often complicate comprehension of glassy polymers' behavior in applications such as high-performance membranes, adsorbents or catalysts. Mixed-penetrant effects are typically very challenging to study directly and their understanding is necessary owing to a broadly recognized inadequacy of simple extrapolations from measurements in pure component environment.

  20. Non-ohmic transport behavior in ultra-thin gold films

    International Nuclear Information System (INIS)

    Alkhatib, A.; Souier, T.; Chiesa, M.

    2011-01-01

    Highlights: → C-AFM study on ultra-thin gold films. → Connection between ultra-thin film morphology and lateral electrical transport. → Transition between ohmic and non-ohmic behavior. → Electrical transition correlation to the film structure continuity. → Direct and indirect tunneling regimes related to discontinuous structures. - Abstract: Structure and local lateral electrical properties of Au films of thicknesses ranging from 10 to 140 nm are studied using conductive atomic force microscopy. Comparison of current maps taken at different thicknesses reveals surprising highly resistive regions (10 10 -10 11 Ω), the density of which increases strongly at lower thickness. The high resistivity is shown to be directly related to discontinuities in the metal sheet. Local I-V curves are acquired to show the nature of electrical behavior relative to thickness. Results show that in Au films of higher thickness the electrical behavior is ohmic, while it is non-ohmic in highly discontinuous films of lower thickness, with the transition happening between 34 and 39 nm. The non-ohmic behavior is explained with tunneling occurring between separated Au islands. The results explain the abrupt increase of electrical resistivity at lower thin film thicknesses.

  1. Mixed-Penetrant Sorption in Ultra-Thin Films of Polymer of Intrinsic Microporosity PIM-1

    KAUST Repository

    Ogieglo, Wojciech

    2017-10-12

    Mixed penetrant sorption into ultra-thin films of a super-glassy polymer of intrinsic microporosity (PIM-1) was studied for the first time by using interference-enhanced in-situ spectroscopic ellipsometry. PIM-1 swelling and the concurrent changes in its refractive index were determined in ultra-thin (12 - 14 nm) films exposed to pure and mixed penetrants. The penetrants included water, n-hexane and ethanol and were chosen based on their significantly different penetrant-penetrant and penetrant-polymer affinities. This allowed studying microporous polymer responses at diverse ternary compositions and revealed effects such as competition for the sorption sites (for water / n-hexane or ethanol / n-hexane) or enhancement in sorption of typically weakly sorbing water in the presence of more highly sorbing ethanol. The results reveal details of the mutual sorption effects which often complicate comprehension of glassy polymers\\' behavior in applications such as high-performance membranes, adsorbents or catalysts. Mixed-penetrant effects are typically very challenging to study directly and their understanding is necessary owing to a broadly recognized inadequacy of simple extrapolations from measurements in pure component environment.

  2. Ultra-thin silicon/electro-optic polymer hybrid waveguide modulators

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Feng; Spring, Andrew M. [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Sato, Hiromu [Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Maeda, Daisuke; Ozawa, Masa-aki; Odoi, Keisuke [Nissan Chemical Industries, Ltd., 2-10-1 Tuboi Nishi, Funabashi, Chiba 274-8507 (Japan); Aoki, Isao; Otomo, Akira [National Institute of Information and Communications Technology, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492 (Japan); Yokoyama, Shiyoshi, E-mail: s-yokoyama@cm.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan)

    2015-09-21

    Ultra-thin silicon and electro-optic (EO) polymer hybrid waveguide modulators have been designed and fabricated. The waveguide consists of a silicon core with a thickness of 30 nm and a width of 2 μm. The cladding is an EO polymer. Optical mode calculation reveals that 55% of the optical field around the silicon extends into the EO polymer in the TE mode. A Mach-Zehnder interferometer (MZI) modulator was prepared using common coplanar electrodes. The measured half-wave voltage of the MZI with 7 μm spacing and 1.3 cm long electrodes is 4.6 V at 1550 nm. The evaluated EO coefficient is 70 pm/V, which is comparable to that of the bulk EO polymer film. Using ultra-thin silicon is beneficial in order to reduce the side-wall scattering loss, yielding a propagation loss of 4.0 dB/cm. We also investigated a mode converter which couples light from the hybrid EO waveguide into a strip silicon waveguide. The calculation indicates that the coupling loss between these two devices is small enough to exploit the potential fusion of a hybrid EO polymer modulator together with a silicon micro-photonics device.

  3. Towards ultra-thin plasmonic silicon wafer solar cells with minimized efficiency loss.

    Science.gov (United States)

    Zhang, Yinan; Stokes, Nicholas; Jia, Baohua; Fan, Shanhui; Gu, Min

    2014-05-13

    The cost-effectiveness of market-dominating silicon wafer solar cells plays a key role in determining the competiveness of solar energy with other exhaustible energy sources. Reducing the silicon wafer thickness at a minimized efficiency loss represents a mainstream trend in increasing the cost-effectiveness of wafer-based solar cells. In this paper we demonstrate that, using the advanced light trapping strategy with a properly designed nanoparticle architecture, the wafer thickness can be dramatically reduced to only around 1/10 of the current thickness (180 μm) without any solar cell efficiency loss at 18.2%. Nanoparticle integrated ultra-thin solar cells with only 3% of the current wafer thickness can potentially achieve 15.3% efficiency combining the absorption enhancement with the benefit of thinner wafer induced open circuit voltage increase. This represents a 97% material saving with only 15% relative efficiency loss. These results demonstrate the feasibility and prospect of achieving high-efficiency ultra-thin silicon wafer cells with plasmonic light trapping.

  4. Dependence of the organic nonvolatile memory performance on the location of ultra-thin Ag film

    International Nuclear Information System (INIS)

    Jiao Bo; Wu Zhaoxin; He Qiang; Mao Guilin; Hou Xun; Tian Yuan

    2010-01-01

    We demonstrated organic nonvolatile memory devices based on 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino] triphenylamine (m-MTDATA) inserted by an ultra-thin Ag film. The memory devices with different locations of ultra-thin Ag film in m-MTDATA were investigated, and it was found that the location of the Ag film could affect the performance of the organic memory, such as ON/OFF ratio, retention time and cycling endurance. When the Ag film was located at the ITO/m-MTDATA interface, the largest ON/OFF ratio (about 10 5 ) could be achieved, but the cycling endurance was poor. When the Ag film was located in the middle region of the m-MTDATA layer, the ON/OFF ratios came down by about 10 3 , but better performance of cycling endurance was exhibited. When the Ag film was located close to the Al electrode, the ON/OFF ratios and the retention time of this device decreased sharply and the bistable phenomenon almost disappeared. Our works show a simple approach to improve the performance of organic memory by adjusting the location of the metal film.

  5. Ultra thin hydro-films based on lactose-crosslinked fish gelatin for wound healing applications.

    Science.gov (United States)

    Etxabide, Alaitz; Vairo, Claudia; Santos-Vizcaino, Edorta; Guerrero, Pedro; Pedraz, Jose Luis; Igartua, Manoli; de la Caba, Koro; Hernandez, Rosa Maria

    2017-09-15

    This study focuses on the development and characterization of an ultra thin hydro-film based on lactose-mediated crosslinking of fish gelatin by Maillard reaction. Lactose results in the only efficient crosslinker able to produce resistant to handling hydro-films when compared to conventional crosslinkers such as glutaraldehyde or genipin (tested at 25 and 37°C in phosphate buffer saline solution (PBS)).The disappearance of the peak related to the N-containing groups (XPS) and the images obtained by SEM and AFM demonstrate the highly ordered nano-scaled structure of lactose-crosslinked gelatin, confirming the crosslinking efficiency. This dressing presents high hydrophilicity and mild occlusivity, as shown by the swelling curve (max swelling at 5min) and by the occlusion factor of 25.17±0.99%, respectively. It demonstrates high stability to hydrolysis or cell-mediated degradation. Moreover, ISO 10993-5:2009 biocompatibility assay results in undetectable cytotoxicity effects. Spreading, adhesion and proliferation assays confirm the excellent adaptability of the cells onto the hydro-film surface without invading the dressing. Finally, the hydro-film enables the controlled delivery of therapeutic factors, such as the epidermal growth factor (EGF). This study demonstrates that lactose-mediated crosslinking is able to produce ultra thin gelatin hydro-films with suitable properties for biomedical applications, such as wound healing. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Electroluminescence of organic light-emitting diodes with an ultra-thin layer of dopant

    Energy Technology Data Exchange (ETDEWEB)

    Li Weizhi [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu Junsheng [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)], E-mail: jsyu@uestc.edu.cn; Wang, Tao [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Jiang, Yadong [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)], E-mail: jiangyd@uestc.edu.cn; Wei, Bangxiong [State Key Lab of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2008-03-15

    Conventional fluorescent dyes, i.e., 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB), 5,12-dihydro-5,12-dimethylquino [2,3-b]acridine-7,14-dione (DMQA) and 5,6,11,12-tetraphenylnaphthacene (Rubrene), were used to investigate the performance of organic light-emitting diodes (OLEDs) based on indium tin oxide (ITO)/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB)/tris-(8-hydroxyquinolate)-aluminum (Alq{sub 3})/MgAg. The dyes were either inserted into devices as an ultra-thin film at the NPB/Alq{sub 3} interface by sequential evaporation, or doped into the Alq{sub 3} emission layer by co-evaporation with the doping ratio about 2%. Electroluminescence (EL) spectra of devices indicated that concentration quenching effect (CQE) of the dye-dopant was slightly bigger in the former than in the latter, while the degrees of CQE for three dopants are in the order of DMQA > DCJTB > Rubrene suggested by the difference in EL spectra and performances of devices. In addition, EL process of device with an ultra-thin layer of dopant is dominated by direct carrier trapping (DCT) process due to almost no holes recombine with electrons in Alq{sub 3}-host layer.

  7. Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong; Mi, Hongyi; Kim, Munho; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Zhao, Deyin; Zhou, Weidong [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yin, Xin; Wang, Xudong [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-05-04

    In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.

  8. Colored ultra-thin hybrid photovoltaics with high quantum efficiency for decorative PV applications (Presentation Recording)

    Science.gov (United States)

    Guo, L. Jay

    2015-10-01

    This talk will describe an approach to create architecturally compatible and decorative thin-film-based hybrid photovoltaics [1]. Most current solar panels are fabricated via complex processes using expensive semiconductor materials, and they are rigid and heavy with a dull, black appearance. As a result of their non-aesthetic appearance and weight, they are primarily installed on rooftops to minimize their negative impact on building appearance. Recently we introduced dual-function solar cells based on ultra-thin dopant-free amorphous silicon embedded in an optical cavity that not only efficiently extract the photogenerated carriers but also display distinctive colors with the desired angle-insensitive appearances [1,2]. The angle-insensitive behavior is the result of an interesting phase cancellation effect in the optical cavity with respect to angle of light propagation [3]. In order to produce the desired optical effect, the semiconductor layer should be ultra-thin and the traditional doped layers need to be eliminated. We adopted the approach of employing charge transport/blocking layers used in organic solar cells to meet this demand. We showed that the ultra-thin (6 to 31 nm) undoped amorphous silicon/organic hybrid solar cell can transmit desired wavelength of light and that most of the absorbed photons in the undoped a-Si layer contributed to the extracted electric charges. This is because the a-Si layer thickness is smaller than the charge diffusion length, therefore the electron-hole recombination is strongly suppressed in such ultra-thin layer. Reflective colored PVs can be made in a similar fashion. Light-energy-harvesting colored signage was demonstrated. Furthermore, a cascaded photovoltaics scheme based on tunable spectrum splitting can be employed to increase power efficiency by absorbing a broader band of light energy. Our work provides a guideline for optimizing a photoactive layer thickness in high efficiency hybrid PV design, which can be

  9. Electronic structure evolution in doping of fullerene (C{sub 60}) by ultra-thin layer molybdenum trioxide

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chenggong; Wang, Congcong; Kauppi, John [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Liu, Xiaoliang [Institute for Super-microstructure and Ultrafast Process in Advanced Materials (ISUPAM), Central South University, Changsha, Hunan 410083 (China); Gao, Yongli, E-mail: ygao@pas.rochester.edu [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Institute for Super-microstructure and Ultrafast Process in Advanced Materials (ISUPAM), Central South University, Changsha, Hunan 410083 (China)

    2015-08-28

    Ultra-thin layer molybdenum oxide doping of fullerene has been investigated using ultraviolet photoemission spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS). The highest occupied molecular orbital (HOMO) can be observed directly with UPS. It is observed that the Fermi level position in fullerene is modified by ultra-thin-layer molybdenum oxide doping, and the HOMO onset is shifted to less than 1.3 eV below the Fermi level. The XPS results indicate that charge transfer was observed from the C{sub 60} to MoO{sub x} and Mo{sup 6+} oxides is the basis as hole dopants.

  10. Sb interactions with TaC precipitates and Cu in ion-implanted α-Fe

    International Nuclear Information System (INIS)

    Follstaedt, D.M.; Myers, S.M.

    1980-01-01

    The interactions of Sb with the other species implanted into Fe to form Fe-Ta-C-Sb and Fe-Cu-Sb alloys have been examined with transmission electron microscopy and Rutherford backscattering following annealing at 873 0 K. Trapping of Sb at TaC precipitates is observed in the former alloy just as was previously observed in Fe-Ti-C-Sb. In Fe-Cu-Sb, Sb interactions are governed by the atomic ratio of Sb to Cu. For ratios between 0.2 to 0.4, the compound β-Cu 3 Sb was observed to form. For Sb to Cu ratios approx.< 0.1, fcc Cu precipitates were observed. In addition to the expected Sb dissolution in Cu, Sb trapping by Cu precipitates is also observed. The binding enthalpy of Sb at both TaC and Cu precipitates with respect to a solution site in the bcc Fe is the same as observed for TiC, approx. 0.4 eV. The constancy of the binding enthalpy at such chemically dissimilar precipitates supports the hypothesis that the trapping is due to the structural discontinuity of the precipitate-host interface. The observed Sb trapping at precipitates is of potential significance for the control of temper embrittlement in bcc steels

  11. Structural and electrical characterization of ultra-thin SrTiO3 tunnel barriers grown over YBa2Cu3O7 electrodes for the development of high Tc Josephson junctions.

    Science.gov (United States)

    Félix, L Avilés; Sirena, M; Guzmán, L A Agüero; Sutter, J González; Vargas, S Pons; Steren, L B; Bernard, R; Trastoy, J; Villegas, J E; Briático, J; Bergeal, N; Lesueur, J; Faini, G

    2012-12-14

    The transport properties of ultra-thin SrTiO(3) (STO) layers grown over YBa(2)Cu(3)O(7) electrodes were studied by conductive atomic force microscopy at the nano-scale. A very good control of the barrier thickness was achieved during the deposition process. A phenomenological approach was used to obtain critical parameters regarding the structural and electrical properties of the system. The STO layers present an energy barrier of 0.9 eV and an attenuation length of 0.23 nm, indicating very good insulating properties for the development of high-quality Josephson junctions.

  12. Structural and electrical characterization of ultra-thin SrTiO3 tunnel barriers grown over YBa2Cu3O7 electrodes for the development of high Tc Josephson junctions

    International Nuclear Information System (INIS)

    Avilés Félix, L; Sirena, M; Agüero Guzmán, L A; González Sutter, J; Pons Vargas, S; Steren, L B; Bernard, R; Trastoy, J; Villegas, J E; Briático, J; Bergeal, N; Lesueur, J; Faini, G

    2012-01-01

    The transport properties of ultra-thin SrTiO 3 (STO) layers grown over YBa 2 Cu 3 O 7 electrodes were studied by conductive atomic force microscopy at the nano-scale. A very good control of the barrier thickness was achieved during the deposition process. A phenomenological approach was used to obtain critical parameters regarding the structural and electrical properties of the system. The STO layers present an energy barrier of 0.9 eV and an attenuation length of 0.23 nm, indicating very good insulating properties for the development of high-quality Josephson junctions. (paper)

  13. Continuous Ultra-Thin MOS2 Films Grown by Low-Temperature Physical Vapor Deposition (Postprint)

    Science.gov (United States)

    2014-07-01

    MoS2 target of 99.95% purity. The SiO2 and highly oriented pyrolitic graphite (HOPG) substrates were intro- duced via a vacuum load- lock and mounted on...im- mediately prior insertion into a sample vacuum load- lock . In this work, the samples were heated to 350 C and allowed to rotate at approximately...136805 (2010). 6H. Terrones, F. Lopez-Urias, and M. Terrones, Sci. Rep. 3(203), 1549 (2013). 7H. Li, Q. Zhang, C. C. R. Yap, B. K. Tay, T. H. T. Edwin

  14. Comment on 'extrinsic versus intrinsic ferroelectric switching : experimental investigations using ultra-thin PVDF Langmuir-Blodgett films'

    NARCIS (Netherlands)

    Naber, R.C.G.; Blom, P.W.M.; de Leeuw, DM

    2006-01-01

    Previous work on ultra-thin P(VDF-TrFE) Langmuir-Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work reported by Kliem et al argues against intrinsic switching. In this Comment

  15. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices

    Science.gov (United States)

    Ahamed, Mohammad Shahed; Saito, Yuji; Mashiko, Koichi; Mochizuki, Masataka

    2017-11-01

    In recent years, heat pipes have been widely used in various hand held mobile electronic devices such as smart phones, tablet PCs, digital cameras. With the development of technology these devices have different user friendly features and applications; which require very high clock speeds of the processor. In general, a high clock speed generates a lot of heat, which needs to be spreaded or removed to eliminate the hot spot on the processor surface. However, it is a challenging task to achieve proper cooling of such electronic devices mentioned above because of their confined spaces and concentrated heat sources. Regarding this challenge, we introduced an ultra-thin heat pipe; this heat pipe consists of a special fiber wick structure named as "Center Fiber Wick" which can provide sufficient vapor space on the both sides of the wick structure. We also developed a cooling module that uses this kind of ultra-thin heat pipe to eliminate the hot spot issue. This cooling module consists of an ultra-thin heat pipe and a metal plate. By changing the width, the flattened thickness and the effective length of the ultra-thin heat pipe, several experiments have been conducted to characterize the thermal properties of the developed cooling module. In addition, other experiments were also conducted to determine the effects of changes in the number of heat pipes in a single module. Characterization and comparison of the module have also been conducted both experimentally and theoretically.

  16. Probing the surface swelling in ultra-thin supported polystyrene films during case II diffusion of n-hexane

    NARCIS (Netherlands)

    Ogieglo, Wojciech; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck Edwin

    2013-01-01

    In situ time-resolved spectroscopic ellipsometry is used to study the dynamics of n-hexane diffusion into, and the corresponding induced swelling of, ultra-thin polystyrene films. The experimental conditions are carefully selected to facilitate the observation of anomalous Case II diffusion in the

  17. Thermodynamical fluctuations and critical behavior in weakly disordered YBCO thin and ultra-thin films

    International Nuclear Information System (INIS)

    Lesueur, J.; Aprili, M.; Degoy, S.; Chambonnet, D.; Keller, D.

    1996-01-01

    The specific role of disorder in the transport properties of YBCO has been investigated, using both light-ion irradiation of thin films to finely tune the amount of atomic disorder, and ultra-thin films grown to study possible dimensional effects. For weak disorder, the samples display a resistive transition typical of the mean-field paraconductive regime of a homogeneous media, well described by the Lawrence and Doniach model for layered superconductors. As the disorder increases, two effects take place. First, the c-axis coherence length becomes shorter, leading to a more anisotropic material, as shown by the excess conductivity above T c . Second, an incipient granularity is revealed, leading to a less sharper transition, which is analyzed within the random 3D XY critical model for the paracoherence transition. Two main results are derived: an experimental test of the Ginzburg criteria for the paracoherence transition, and a new fluctuation regime in nanometric grain size superconductors

  18. Wavelength-tunable colloidal quantum dot laser on ultra-thin flexible glass

    Energy Technology Data Exchange (ETDEWEB)

    Foucher, C.; Guilhabert, B.; Laurand, N.; Dawson, M. D. [Institute of Photonics, SUPA, University of Strathclyde, Glasgow (United Kingdom)

    2014-04-07

    A mechanically flexible and wavelength-tunable laser with an ultra-thin glass membrane as substrate is demonstrated. The optically pumped hybrid device has a distributed feedback cavity that combines a colloidal quantum dot gain film with a grating-patterned polymeric underlayer, all on a 30-μm thick glass sheet. The total thickness of the structure is only 75 μm. The hybrid laser has an average threshold fluence of 450 ± 80 μJ/cm{sup 2} (for 5-ns excitation pulses) at an emitting wavelength of 607 nm. Mechanically bending the thin-glass substrate enables continuous tuning of the laser emission wavelength over an 18-nm range, from 600 nm to 618 nm. The correlation between the wavelength tunability and the mechanical properties of the thin laser structure is verified theoretically and experimentally.

  19. Local variation of fragility and glass transition temperature of ultra-thin supported polymer films.

    Science.gov (United States)

    Hanakata, Paul Z; Douglas, Jack F; Starr, Francis W

    2012-12-28

    Despite extensive efforts, a definitive picture of the glass transition of ultra-thin polymer films has yet to emerge. The effect of film thickness h on the glass transition temperature T(g) has been widely examined, but this characterization does not account for the fragility of glass-formation, which quantifies how rapidly relaxation times vary with temperature T. Accordingly, we simulate supported polymer films of a bead-spring model and determine both T(g) and fragility, both as a function of h and film depth. We contrast changes in the relaxation dynamics with density ρ and demonstrate the limitations of the commonly invoked free-volume layer model. As opposed to bulk polymer materials, we find that the fragility and T(g) do not generally vary proportionately. Consequently, the determination of the fragility profile--both locally and for the film as a whole--is essential for the characterization of changes in film dynamics with confinement.

  20. Intrinsic radiation tolerance of ultra-thin GaAs solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirst, L. C.; Yakes, M. K.; Warner, J. H.; Schmieder, K. J.; Walters, R. J.; Jenkins, P. P. [U.S. Naval Research Laboratory, 4555 Overlook Ave. SW., Washington, D.C. 20375 (United States); Bennett, M. F. [Sotera Defense Solutions, Inc., Annapolis Junction, Maryland 20701-1067 (United States)

    2016-07-18

    Radiation tolerance is a critical performance criterion of photovoltaic devices for space power applications. In this paper we demonstrate the intrinsic radiation tolerance of an ultra-thin solar cell geometry. Device characteristics of GaAs solar cells with absorber layer thicknesses 80 nm and 800 nm were compared before and after 3 MeV proton irradiation. Both cells showed a similar degradation in V{sub oc} with increasing fluence; however, the 80 nm cell showed no degradation in I{sub sc} for fluences up to 10{sup 14 }p{sup +} cm{sup −2}. For the same exposure, the I{sub sc} of the 800 nm cell had severely degraded leaving a remaining factor of 0.26.

  1. Effect of ambient on electrical transport properties of ultra-thin Au nanowires

    Science.gov (United States)

    Amin, Kazi Rafsanjani; Kundu, Subhajit; Biswas, Sangram; Roy, Ahin; Singh, Abhishek Kumar; Ravishankar, N.; Bid, Aveek

    2016-12-01

    In this letter we present systematic studies of the dynamics of surface adsorption of various chemicals on ultra-thin single crystalline gold nanowires (AuNW) through sensitive resistance fluctuation spectroscopy measurements coupled with ab initio simulations. We show that, contrary to expectations, the adsorption of common chemicals like methanol and acetone has a profound impact on the electrical transport properties of the AuNW. Our measurements and subsequent calculations establish conclusively that in AuNW, semiconductor-like sensitivity to the ambient arises because of changes induced in its local density of states by the surface adsorbed molecules. The extreme sensitivity of the resistance fluctuations of the AuNW to ambient suggests their possible use as solid-state sensors.

  2. Dynamics and morphology of chiral magnetic bubbles in perpendicularly magnetized ultra-thin films

    Science.gov (United States)

    Sarma, Bhaskarjyoti; Garcia-Sanchez, Felipe; Nasseri, S. Ali; Casiraghi, Arianna; Durin, Gianfranco

    2018-06-01

    We study bubble domain wall dynamics using micromagnetic simulations in perpendicularly magnetized ultra-thin films with disorder and Dzyaloshinskii-Moriya interaction. Disorder is incorporated into the material as grains with randomly distributed sizes and varying exchange constant at the edges. As expected, magnetic bubbles expand asymmetrically along the axis of the in-plane field under the simultaneous application of out-of-plane and in-plane fields. Remarkably, the shape of the bubble has a ripple-like part which causes a kink-like (steep decrease) feature in the velocity versus in-plane field curve. We show that these ripples originate due to the nucleation and interaction of vertical Bloch lines. Furthermore, we show that the Dzyaloshinskii-Moriya interaction field is not constant but rather depends on the in-plane field. We also extend the collective coordinate model for domain wall motion to a magnetic bubble and compare it with the results of micromagnetic simulations.

  3. Performance regeneration of InGaZnO transistors with ultra-thin channels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Binglei; Li, He; Zhang, Xijian, E-mail: zhangxijian@sdu.edu.cn, E-mail: songam@sdu.edu.cn; Luo, Yi; Wang, Qingpu [School of Physics, Shandong University, Jinan 250100 (China); Song, Aimin, E-mail: zhangxijian@sdu.edu.cn, E-mail: songam@sdu.edu.cn [School of Physics, Shandong University, Jinan 250100 (China); School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom)

    2015-03-02

    Thin-film transistors (TFTs) based on ultra-thin amorphous indium gallium zinc oxide (a-IGZO) semiconductors down to 4 nm were studied motivated by the increasing cost of indium. At and below 5 nm, it was found that the field-effect mobility was severely degraded, the threshold voltage increased, and the output characteristics became abnormal showing no saturated current. By encapsulating a layer of polymethyl methacrylate on the IGZO TFTs, the performance of the 5-nm-thick device was effectively recovered. The devices also showed much higher on/off ratios, improved hysteresis, and normal output characteristic curves as compared with devices not encapsulated. The stability of the encapsulated devices was also studied over a four month period.

  4. Ultra-thin, conformal, and hydratable color-absorbers using silk protein hydrogel

    Science.gov (United States)

    Umar, Muhammad; Min, Kyungtaek; Jo, Minsik; Kim, Sunghwan

    2018-06-01

    Planar and multilayered photonic devices offer unprecedented opportunities in biological and chemical sensing due to strong light-matter interactions. However, uses of rigid substances such as semiconductors and dielectrics confront photonic devices with issues of biocompatibility and a mechanical mismatch for their application on humid, uneven, and soft biological surfaces. Here, we report that favorable material traits of natural silk protein led to the fabrication of an ultra-thin, conformal, and water-permeable (hydratable) metal-insulator-metal (MIM) color absorber that was mapped on soft, curved, and hydrated biological interfaces. Strong absorption was induced in the MIM structure and could be tuned by hydration and tilting of the sample. The transferred MIM color absorbers reached the exhibition of a very strong resonant absorption in the visible and near infra-red ranges. In addition, we demonstrated that the conformal resonator could function as a refractometric glucose sensor applied on a contact lens.

  5. Ultra-Thin Optically Transparent Carbon Electrodes Produced from Layers of Adsorbed Proteins

    Science.gov (United States)

    Alharthi, Sarah A.; Benavidez, Tomas E.; Garcia, Carlos D.

    2013-01-01

    This work describes a simple, versatile, and inexpensive procedure to prepare optically transparent carbon electrodes, using proteins as precursors. Upon adsorption, the protein-coated substrates were pyrolyzed under reductive conditions (5% H2) to form ultra-thin, conductive electrodes. Because proteins spontaneously adsorb to interfaces forming uniform layers, the proposed method does not require a precise control of the preparation conditions, specialized instrumentation, or expensive precursors. The resulting electrodes were characterized by a combination of electrochemical, optical, and spectroscopic means. As a proof-of-concept, the optically-transparent electrodes were also used as substrate for the development of an electrochemical glucose biosensor. The proposed films represent a convenient alternative to more sophisticated, and less available, carbon-based nanomaterials. Furthermore, these films could be formed on a variety of substrates, without classical limitations of size or shape. PMID:23421732

  6. Static and low frequency noise characterization of ultra-thin body InAs MOSFETs

    Science.gov (United States)

    Karatsori, T. A.; Pastorek, M.; Theodorou, C. G.; Fadjie, A.; Wichmann, N.; Desplanque, L.; Wallart, X.; Bollaert, S.; Dimitriadis, C. A.; Ghibaudo, G.

    2018-05-01

    A complete static and low frequency noise characterization of ultra-thin body InAs MOSFETs is presented. Characterization techniques, such as the well-known Y-function method established for Si MOSFETs, are applied in order to extract the electrical parameters and study the behavior of these research grade devices. Additionally, the Lambert-W function parameter extraction methodology valid from weak to strong inversion is also used in order to verify its applicability in these experimental level devices. Moreover, a low-frequency noise characterization of the UTB InAs MOSFETs is presented, revealing carrier trapping/detrapping in slow oxide traps and remote Coulomb scattering as origin of 1/f noise, which allowed for the extraction of the oxide trap areal density. Finally, Lorentzian-like noise is also observed in the sub-micron area devices and attributed to both Random Telegraph Noise from oxide individual traps and g-r noise from the semiconductor interface.

  7. Degradation of Ultra-Thin Gate Oxide NMOSFETs under CVDT and SHE Stresses

    International Nuclear Information System (INIS)

    Shi-Gang, Hu; Yan-Rong, Cao; Yue, Hao; Xiao-Hua, Ma; Chi, Chen; Xiao-Feng, Wu; Qing-Jun, Zhou

    2008-01-01

    Degradation of device under substrate hot-electron (SHE) and constant voltage direct-tunnelling (CVDT) stresses are studied using NMOSFET with 1.4-nm gate oxides. The degradation of device parameters and the degradation of the stress induced leakage current (SILC) under these two stresses are reported. The emphasis of this paper is on SILC and breakdown of ultra-thin-gate-oxide under these two stresses. SILC increases with stress time and several soft breakdown events occur during direct-tunnelling (DT) stress. During SHE stress, SILC firstly decreases with stress time and suddenly jumps to a high level, and no soft breakdown event is observed. For DT injection, the positive hole trapped in the oxide and hole direct-tunnelling play important roles in the breakdown. For SHE injection, it is because injected hot electrons accelerate the formation of defects and these defects formed by hot electrons induce breakdown. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  8. Structure of a zinc oxide ultra-thin film on Rh(100)

    Energy Technology Data Exchange (ETDEWEB)

    Yuhara, J.; Kato, D.; Matsui, T. [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Mizuno, S. [Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816–8580 (Japan)

    2015-11-07

    The structural parameters of ultra-thin zinc oxide films on Rh(100) are investigated using low-energy electron diffraction intensity (LEED I–V) curves, scanning tunneling microscopy (STM), and first-principles density functional theory (DFT) calculations. From the analysis of LEED I–V curves and DFT calculations, two optimized models A and B are determined. Their structures are basically similar to the planer h-BN ZnO(0001) structure, although some oxygen atoms protrude from the surface, associated with an in-plane shift of Zn atoms. From a comparison of experimental STM images and simulated STM images, majority and minority structures observed in the STM images represent the two optimized models A and B, respectively.

  9. Mesoporous polyaniline film on ultra-thin graphene sheets for high performance supercapacitors

    Science.gov (United States)

    Wang, Qian; Yan, Jun; Fan, Zhuangjun; Wei, Tong; Zhang, Milin; Jing, Xiaoyan

    2014-02-01

    A facile approach has been developed to fabricate mesoporous PANI film on ultra-thin graphene nanosheet (G-mPANI) hybrid by in situ polymerization using graphene-mesoporous silica composite as template. Due to its mesoporous structure, over-all conductive network, G-mPANI electrode displays a specific capacitance of 749 F g-1 at 0.5 A g-1 with excellent rate capability (remains 73% even at 5.0 A g-1), much higher than that of pristine PANI electrode (315 F g-1 at 0.5 A g-1, 39% retention at 5.0 A g-1) in 1 mol L-1 H2SO4 aqueous solution. More interestingly, the G-mPANI hybrid can maintain 88% of its initial capacitance compared to 45% for pristine PANI after 1000 cycles, suggesting a superior electrochemical cyclic stability.

  10. How Do Organic Vapors Swell Ultra-Thin PIM-1 Films?

    KAUST Repository

    Ogieglo, Wojciech

    2017-06-22

    Dynamic sorption of ethanol and toluene vapor into ultra-thin supported PIM-1 films down to 6 nm are studied with a combination of in-situ spectroscopic ellipsometry and in-situ X-ray reflectivity. Both ethanol and toluene significantly swell the PIM-1 matrix and, at the same time, induce persistent structural relaxations of the frozen-in glassy PIM-1 morphology. For ethanol below 20 nm three effects were identified. First, the swelling magnitude at high vapor pressures is reduced by about 30% as compared to thicker films. Second, at low penetrant activities (below 0.3 p/p0) films below 20 nm are able to absorb slightly more penetrant as compared with thicker films despite similar swelling magnitude. Third, for the ultra-thin films the onset of the dynamic penetrant-induced glass transition Pg has been found to shift to higher values indicating higher resistance to plasticization. All of these effects are consistent with a view where immobilization of the super-glassy PIM-1 at the substrate surface leads to an arrested, even more rigid and plasticization-resistant, yet still very open, microporous structure. PIM-1 in contact with the larger and more condensable toluene shows very complex, heterogeneous swelling dynamics and two distinct penetrant-induced relaxation phenomena, probably associated with the film outer surface and the bulk, are detected. Following the direction of the penetrant\\'s diffusion the surface seems to plasticize earlier than the bulk and the two relaxations remain well separated down to 6 nm film thickness, where they remarkably merge to form just a single relaxation.

  11. Mechanical properties of ultra thin metallic films revealed by synchrotron techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Patric Alfons

    2007-07-20

    A prerequisite for the study of the scaling behavior of mechanical properties of ultra thin films is a suitable testing technique. Therefore synchrotron-based in situ testing techniques were developed and optimized in order to characterize the stress evolution in ultra thin metallic films on compliant polymer substrates during isothermal tensile tests. Experimental procedures for polycrystalline as well as single crystalline films were established. These techniques were used to systematically investigate the influence of microstructure, film thickness (20 to 1000 nm) and temperature (-150 to 200 C) on the mechanical properties. Passivated and unpassivated Au and Cu films as well as single crystalline Au films on polyimide substrates were tested. Special care was also dedicated to the microstructural characterization of the samples which was very important for the correct interpretation of the results of the mechanical tests. Down to a film thickness of about 100 to 200 nm the yield strength increased for all film systems (passivated and unpassivated) and microstructures (polycrystalline and singlecrystalline). The influence of different interfaces was smaller than expected. This could be explained by a dislocation source model based on the nucleation of perfect dislocations. For polycrystalline films the film thickness as well as the grain size distribution had to be considered. For smaller film thicknesses the increase in flow stress was weaker and the deformation behavior changed because the nucleation of perfect dislocations became unfavorable. Instead, the film materials used alternative mechanisms to relieve the high stresses. For regular and homogeneous deformation the total strain was accommodated by the nucleation and motion of partial dislocations. If the deformation was localized due to initial cracks in a brittle interlayer or local delamination, dislocation plasticity was not effective enough to relieve the stress concentration and the films showed

  12. Performance of a PEM water electrolyser using a TaC-supported iridium oxide electrocatalyst

    DEFF Research Database (Denmark)

    Polonský, J.; Mazúr, P.; Paidar, M.

    2014-01-01

    by dispersing the precious metal compound onto a catalyst support. Electrocatalysts with 50, 70 and 90 wt.% of IrO2 on a TaC support were tested in a laboratory PEM water electrolyser and compared with pure IrO2. The temperature was set at 90, 110, 120 and 130 °C respectively and the cell voltage was varied......Polymer electrolyte membrane (PEM) water electrolysis is an attractive way of producing carbon-free hydrogen. One of the drawbacks of this method is the need for precious metal-based electrocatalysts. This calls for a highly efficient utilization of the precious metal, which can be obtained...

  13. Enhancement of Heat and Mass Transfer in Mechanically Contstrained Ultra Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Drost; Jim Liburdy; Brian Paul; Richard Peterson

    2005-01-01

    Oregon State University (OSU) and the Pacific Northwest National Laboratory (PNNL) were funded by the U.S. Department of Energy to conduct research focused on resolving the key technical issues that limited the deployment of efficient and extremely compact microtechnology based heat actuated absorption heat pumps and gas absorbers. Success in demonstrating these technologies will reduce the main barriers to the deployment of a technology that can significantly reduce energy consumption in the building, automotive and industrial sectors while providing a technology that can improve our ability to sequester CO{sub 2}. The proposed research cost $939,477. $539,477 of the proposed amount funded research conducted at OSU while the balance ($400,000) was used at PNNL. The project lasted 42 months and started in April 2001. Recent developments at the Pacific Northwest National Laboratory and Oregon State University suggest that the performance of absorption and desorption systems can be significantly enhanced by the use of an ultra-thin film gas/liquid contactor. This device employs microtechnology-based structures to mechanically constrain the gas/liquid interface. This technology can be used to form very thin liquid films with a film thickness less then 100 microns while still allowing gas/liquid contact. When the resistance to mass transfer in gas desorption and absorption is dominated by diffusion in the liquid phase the use of extremely thin films (<100 microns) for desorption and absorption can radically reduce the size of a gas desorber or absorber. The development of compact absorbers and desorbers enables the deployment of small heat-actuated absorption heat pumps for distributed space heating and cooling applications, heat-actuated automotive air conditioning, manportable cooling, gas absorption units for the chemical process industry and the development of high capacity CO{sub 2} absorption devices for CO{sub 2} collection and sequestration. The energy

  14. Effect of anionic dopants on thickness, morphology and electrical properties of polypyrrole ultra-thin films prepared by in situ chemical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoodian, Mehrnoosh [Dep. of Polymer Engineering, Nanostructured Materials Research Center, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of); Pourabbas, Behzad, E-mail: pourabas@sut.ac.ir [Dep. of Polymer Engineering, Nanostructured Materials Research Center, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of); Mohajerzadeh, Shams [Nano-Electronics and Thin Film Lab, School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of)

    2015-05-29

    The effect of different dopant anions on deposition and characteristics of polypyrrole (PPy) thin film has been studied in this work. Ultra-thin films of conducting PPy were deposited on insulating surfaces of glass and oxidized silicon wafer by in situ chemical polymerization in the presence of different anionic dopants including sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, α-naphthalene sulfonic acid, anthraquinone-2-sulfonic acid sodium salt monohydrate/5-sulfosalicylic acid dehydrate, and camphor sulfonic acid. Hydrophilic/hydrophobic properties and morphology of the self-assembled monolayer of N-(3-trimethoxysilylpropyl)pyrrole, the surface modifying agent in this work, and PPy thin films were characterized before and after deposition by contact angle measurements, field emission scanning electron microscopy, and atomic force microscopy. Chemical structure, thickness, and conductivity of the thin films were also studied by attenuated total reflectance Fourier transform infrared spectrometer, ellipsometry, and four-point probe measurements. The results showed deposition of thin films of conducting PPy with comparable thickness in the range of 6-31 nm and different morphologies, uniformity, and smoothness with average roughness in the range of 0.3-6 nm and relatively high range of conductivity on the modified surfaces. - Highlights: • Conducting thin films of polypyrrole were deposited on glass and SiO{sub 2} substrates. • Surface modification using pyrrole-silane was employed prior to polymerization. • Films as thin as ≈ 7 nm were deposited using different surfactant/counter ions. • Chemistry of the counter ion affects thickness, conductivity and morphology. • Lower thickness/higher conductivity were obtained by structurally flexible dopants.

  15. Ultra-thin flexible GaAs photovoltaics in vertical forms printed on metal surfaces without interlayer adhesives

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Juho; Song, Kwangsun; Kim, Namyun; Lee, Jongho, E-mail: jong@gist.ac.kr [School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Research Institute for Solar and Sustainable Energies (RISE), Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Hwang, Jeongwoo [Photonic Bio Research Center, Korea Photonics Technology Institute (KOPTI), 9 Cheomdanventure-ro 108beon-gil, Gwangju 61007 (Korea, Republic of); Shin, Jae Cheol [Department of Physics, Yeungnam University, Gyeongsan, Gyeongbuk 38541 (Korea, Republic of)

    2016-06-20

    Wearable flexible electronics often require sustainable power sources that are also mechanically flexible to survive the extreme bending that accompanies their general use. In general, thinner microelectronic devices are under less strain when bent. This paper describes strategies to realize ultra-thin GaAs photovoltaics through the interlayer adhesiveless transfer-printing of vertical-type devices onto metal surfaces. The vertical-type GaAs photovoltaic devices recycle reflected photons by means of bottom electrodes. Systematic studies with four different types of solar microcells indicate that the vertical-type solar microcells, at only a quarter of the thickness of similarly designed lateral-type cells, generate a level of electric power similar to that of thicker cells. The experimental results along with the theoretical analysis conducted here show that the ultra-thin vertical-type solar microcells are durable under extreme bending and thus suitable for use in the manufacturing of wearable flexible electronics.

  16. Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

    KAUST Repository

    Yave, Wilfredo

    2010-09-01

    Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform thickness (<100 nm) is crucial. By using a tailor-made polymer and by controlling the nanofabrication conditions, we developed and manufactured defect-free ultra-thin film membranes with unmatched carbon dioxide permeances, i.e. >5 m3 (STP) m-2 h -1 bar-1. The permeances are extremely high, because the membranes are made from a CO2 philic polymer material and they are only a few tens of nanometers thin. Thus, these thin film membranes have potential application in the treatment of large gas streams under low pressure like, e.g., carbon dioxide separation from flue gas. © 2010 IOP Publishing Ltd.

  17. Understanding the role of ultra-thin polymeric interlayers in improving efficiency of polymer light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Jim; Wang, Xuhua; Bradley, Donal D. C.; Kim, Ji-Seon, E-mail: ji-seon.kim@imperial.ac.uk [Department of Physics and Centre for Plastic Electronics, South Kensington Campus, Imperial College London, London SW7 2AZ (United Kingdom); Wright, Edward N.; Walker, Alison B. [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)

    2014-05-28

    Insertion of ultra-thin polymeric interlayers (ILs) between the poly(3,4-ethylenedioxythiophene):polystyrene sulphonate hole injection and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) light emission layers of polymer light emitting diodes (PLEDs) can significantly increase their efficiency. In this paper, we investigate experimentally a broad range of probable causes of this enhancement with an eye to determining which IL parameters have the most significant effects. The importance of hole injection and electron blocking was studied through varying the IL material (and consequently its electronic energy levels) for both PLED and hole-only diode structures. The role of IL conductivity was examined by introducing a varying level of charge-transfer doping through blending the IL materials with a strong electron-accepting small molecule in concentrations from 1% to 7% by weight. Depositing ILs with thicknesses below the exciton diffusion length of ∼15 nm allowed the role of the IL as a physical barrier to exciton quenching to be probed. IL containing PLEDs was also fabricated with Lumation Green Series 1300 (LG 1300) light emission layers. On the other hand, the PLEDs were modeled using a 3D multi-particle Kinetic Monte Carlo simulation coupled with an optical model describing how light is extracted from the PLED. The model describes charge carrier transport and interactions between electrons, holes, singlets, and triplets, with the current density, luminance, and recombination zone (RZ) locations calculated for each PLED. The model shows F8BT PLEDs have a narrow charge RZ adjacent to the anode, while LG 1300 PLEDs have a wide charge RZ that is evenly distributed across the light emitting layer. Varying the light emitting layer from F8BT to Lumation Green Series 1300, we therefore experimentally examine the dependence of the IL function, specifically in regard to anode-side exciton quenching, on the location of the RZ. We found an exponential dependence of

  18. A novel ultra-thin 3D detector-For plasma diagnostics at JET and ITER tokamaks

    International Nuclear Information System (INIS)

    Garcia, Francisco; Pelligrini, G.; Balbuena, J.; Lozano, M.; Orava, R.; Ullan, M.

    2009-01-01

    A novel ultra-thin silicon detector called U3DTHIN has been designed and built for applications that range from Neutral Particle Analyzers (NPA) used in Corpuscular Diagnostics of High Temperature Plasma to very low X-ray spectroscopy. The main purpose of this detector is to provide a state-of-the-art solution to upgrade the current detector system of the NPAs at JET and also to pave the road for the future detection systems of the ITER experimental reactor. Currently the NPAs use a very thin scintillator-photomultiplier tube [F. Garcia, S.S. Kozlovsky, D.V. Balin, Background Properties of CEM, MCP and PMT detectors at n-γ irradiation. Preprint PNPI-2392, Gatchina, 2000, p. 9 ; F. Garcia, S.S. Kozlovsky, V.V. Ianovsky, Scintillation Detectors with Low Sensitivity to n-γ Background. Preprint PNPI-2391, Gatchina, 2000, p. 8 ], and their main drawbacks are poor energy resolution, intrinsic scintillator nonlinearity, and relative low count rate capability and finally poor signal-to-background discrimination for the low-energy channels. The proposed new U3DTHIN detector is based on very thin sensitive substrate, which will provide nearly 100% detection efficiency for ions and at the same time very low sensitivity for neutron and gamma backgrounds. To achieve a very fast collection of the charge carriers generated by the incident ions, a 3D electrode structure [S. Parker, C. Kenney, J. Segal, Nucl. Instr. and Meth. A 395 (1997) 328 ; G. Pellegrini, P. Roy, A. Al-Ajili, R. Bates, L. Haddad, M. Horn, K. Mathieson, J. Melone, V. O'Shea, K.M. Smith, Nucl. Instr. and Meth. A 487 (2002) 19 ] has been introduced in the sensitive volume of the detector. The geometry of the electrode is known to be rad-hard. One of the most innovative features of these detectors is the optimal combination of the thin entrance window and the sensitive substrate thickness, which allows a very large dynamic range for ion detection. GEANT4 simulations were performed to find the losses of energy in

  19. The production of ultra-thin layers of ion-exchange resin and metallic silver by electrospraying

    International Nuclear Information System (INIS)

    Wyllie, H.A.

    1988-10-01

    Highly efficient radioactive sources for use in radioisotope metrology have been prepared on ultra-thin layers of electrosprayed ion-exchange resin. The efficiency of these sources can be reduced for the purpose of radioactivity standardisation by coating them with conducting silver layers which are also produced by electrospraying. A description is given of improvements to the electrospraying methods, together with details of the rotating, oscillating source-mount turntable

  20. Dynamic Fracture Toughness of TaC/CNTs/SiC CMCs Prepared by Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Qiaoyun Xie

    2015-01-01

    Full Text Available This study focuses on the fracture toughness of TaC and carbon nanotubes (CNTs reinforced SiC ceramic matrix composites (CMCs, prepared by spark plasma sintering (SPS technique. A high densification of 98.4% was achieved under the sintering parameter of 133°C/min, 1800°C, and 90 MPa pressure. Vickers indentation was employed to measure the indentation toughness on the polished surface of ceramic samples, SEM was applied to directly observe the crack propagation after indentation, and split Hopkinson pressure bar (SHPB was developed to determine the dynamic fracture toughness within the ceramic samples subjected to an impact in a three-point bending configuration.

  1. Measured Whole-House Performance of TaC Studios Test Home

    Energy Technology Data Exchange (ETDEWEB)

    Butler, T. [Southface Energy Institute, Upper Marlboro, MD (United States); Curtis, O. [Southface Energy Institute, Upper Marlboro, MD (United States); Stephenson, R. [Southface Energy Institute, Upper Marlboro, MD (United States)

    2013-12-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta-based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA, in the mixed humid climate. This home serves as a residence and home office for the firm's owners, as well as a demonstration of their design approach to potential and current clients. Southface believes the home demonstrates current best practices for the mixed-humid climate, including a building envelope featuring advanced air sealing details and low density spray foam insulation, glazing that exceeds ENERGY STAR requirements, and a high performance heating and cooling system. Construction quality and execution was a high priority for TaC Studios and was ensured by a third party review process. Post-construction testing showed that the project met stated goals for envelope performance, an air infiltration rate of 2.15 ACH50. The homeowners wished to further validate whole house energy savings through the project's involvement with Building America and this long-term monitoring effort. As a Building America test home, this home was evaluated to detail whole house energy use, end use loads, and the efficiency and operation of the ground source heat pump and associated systems. Given that the home includes many non-typical end use loads including a home office, pool, landscape water feature, and other luxury features not accounted for in Building America modeling tools, these end uses were separately monitored to determine their impact on overall energy consumption.

  2. Creation of a longitudinally polarized subwavelength hotspot with an ultra-thin planar lens: vectorial Rayleigh–Sommerfeld method

    International Nuclear Information System (INIS)

    Ye, Huapeng; Qiu, Cheng-Wei; Huang, Kun; Yeo, Swee Ping; Teng, Jinghua; Luk’yanchuk, Boris

    2013-01-01

    This letter shows how a longitudinally polarized hotspot can be created by a planar ultra-thin lens that beats the diffraction limit. On the imaging plane, a subwavelength optical resolution 0.39λ with almost purely longitudinal electric component has been demonstrated in air ambient. This novel paradigm addresses simultaneously both longitudinal polarization and deep sub-diffraction imaging, by a planar lens composed of ultra-thin opaque concentric annuli. The vectorial Rayleigh–Sommerfeld (VRS) approach, offering the advantage of significant reduction in computation, has been developed for a particular optimization of a flat lens with full control of polarization. Empowered by the robustness of VRS in dealing with polarization states, the proposed roadmap may be universally and efficiently integrated with other optimization algorithms to design super-resolution imaging with controlled polarization states at any wavelength without luminescence of the object. The lens, which is empowered by the proposed method, opens an avenue for the first time toward a highly integrated imaging system with advanced functionalities in far-field super-imaging, tailored polarization states and flat ultra-thin geometry simultaneously. (letter)

  3. Magnetic structures in ultra-thin Holmium films: Influence of external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, L.J. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Mello, V.D. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Anselmo, D.H.A.L. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Vasconcelos, M.S., E-mail: mvasconcelos@ect.ufrn.br [Escola de Ciência e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil)

    2015-03-01

    We address the magnetic phases in very thin Ho films at the temperature interval between 20 K and 132 K. We show that slab size, surface effects and magnetic field due to spin ordering impact significantly the magnetic phase diagram. Also we report that there is a relevant reduction of the external field strength required to saturate the magnetization and for ultra-thin films the helical state does not form. We explore the specific heat and the susceptibility as auxiliary tools to discuss the nature of the phase transitions, when in the presence of an external magnetic field and temperature effects. The presence of an external field gives rise to the magnetic phase Fan and the spin-slip structures. - Highlights: • We analyze the magnetic phases of very thin Ho films in the temperature interval 20–132 K. • We show that slab size, etc. due to spin ordering may impact the magnetic phase diagram. • All magnetic phase transitions, for strong magnetic fields, are marked by the specific heat. • The presence of an external field gives rise to the magnetic phase Fan and the spin-slip one.

  4. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    Directory of Open Access Journals (Sweden)

    Mohamed T. Ghoneim

    2015-12-01

    Full Text Available In today’s digital world, complementary metal oxide semiconductor (CMOS technology enabled scaling of bulk mono-crystalline silicon (100 based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm mono-crystalline (100 silicon (detached from bulk substrate by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs with high-κ/metal gate stacks.

  5. Prediction of transmittance spectra for transparent composite electrodes with ultra-thin metal layers

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhao; Alford, T. L., E-mail: TA@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Khorasani, Arash Elhami [ON Semiconductor Corp., Phoenix, Arizona 85005 (United States); Theodore, N. D. [CHD-Fab, Freescale Semiconductor Inc., Tempe, Arizona 85224 (United States); Dhar, A. [Intel Corp., 2501 NW 229th Ave, Hillsboro, Oregon 97124 (United States)

    2015-11-28

    Recent interest in indium-free transparent composite-electrodes (TCEs) has motivated theoretical and experimental efforts to better understand and enhance their electrical and optical properties. Various tools have been developed to calculate the optical transmittance of multilayer thin-film structures based on the transfer-matrix method. However, the factors that affect the accuracy of these calculations have not been investigated very much. In this study, two sets of TCEs, TiO{sub 2}/Au/TiO{sub 2} and TiO{sub 2}/Ag/TiO{sub 2}, were fabricated to study the factors that affect the accuracy of transmittance predictions. We found that the predicted transmittance can deviate significantly from measured transmittance for TCEs that have ultra-thin plasmonic metal layers. The ultrathin metal layer in the TCE is typically discontinuous. When light interacts with the metallic islands in this discontinuous layer, localized surface plasmons are generated. This causes extra light absorption, which then leads to the actual transmittance being lower than the predicted transmittance.

  6. Effects of ultra-thin Si-fin body widths upon SOI PMOS FinFETs

    Science.gov (United States)

    Liaw, Yue-Gie; Chen, Chii-Wen; Liao, Wen-Shiang; Wang, Mu-Chun; Zou, Xuecheng

    2018-05-01

    Nano-node tri-gate FinFET devices have been developed after integrating a 14 Å nitrided gate oxide upon the silicon-on-insulator (SOI) wafers established on an advanced CMOS logic platform. These vertical double gate (FinFET) devices with ultra-thin silicon fin (Si-fin) widths ranging from 27 nm to 17 nm and gate length down to 30 nm have been successfully developed with a 193 nm scanner lithography tool. Combining the cobalt fully silicidation and the CESL strain technology beneficial for PMOS FinFETs was incorporated into this work. Detailed analyses of Id-Vg characteristics, threshold voltage (Vt), and drain-induced barrier lowering (DIBL) illustrate that the thinnest 17 nm Si-fin width FinFET exhibits the best gate controllability due to its better suppression of short channel effect (SCE). However, higher source/drain resistance (RSD), channel mobility degradation due to dry etch steps, or “current crowding effect” will slightly limit its transconductance (Gm) and drive current.

  7. Micro-architecture embedding ultra-thin interlayer to bond diamond and silicon via direct fusion

    Science.gov (United States)

    Kim, Jong Cheol; Kim, Jongsik; Xin, Yan; Lee, Jinhyung; Kim, Young-Gyun; Subhash, Ghatu; Singh, Rajiv K.; Arjunan, Arul C.; Lee, Haigun

    2018-05-01

    The continuous demand on miniaturized electronic circuits bearing high power density illuminates the need to modify the silicon-on-insulator-based chip architecture. This is because of the low thermal conductivity of the few hundred nanometer-thick insulator present between the silicon substrate and active layers. The thick insulator is notorious for releasing the heat generated from the active layers during the operation of devices, leading to degradation in their performance and thus reducing their lifetime. To avoid the heat accumulation, we propose a method to fabricate the silicon-on-diamond (SOD) microstructure featured by an exceptionally thin silicon oxycarbide interlayer (˜3 nm). While exploiting the diamond as an insulator, we employ spark plasma sintering to render the silicon directly fused to the diamond. Notably, this process can manufacture the SOD microarchitecture via a simple/rapid way and incorporates the ultra-thin interlayer for minute thermal resistance. The method invented herein expects to minimize the thermal interfacial resistance of the devices and is thus deemed as a breakthrough appealing to the current chip industry.

  8. Laser Radiation Pressure Acceleration of Monoenergetic Protons in an Ultra-Thin Foil

    Science.gov (United States)

    Eliasson, Bengt; Liu, Chuan S.; Shao, Xi; Sagdeev, Roald Z.; Shukla, Padma K.

    2009-11-01

    We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The stability of the foil is investigated by direct Vlasov-Maxwell simulations for different sets of laser-plasma parameters. It is found that the foil is stable, due to the trapping of both electrons and ions in the thin laser-plasma interaction region, where the electrons are trapped in a potential well composed of the ponderomo-tive potential of the laser light and the electrostatic potential due to the ions, and the ions are trapped in a potential well composed of the inertial potential in an accelerated frame and the electrostatic potential due to the electrons. The result is a stable double layer, where the trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, which makes them suitable for medical applications cancer treatment. The underlying physics of trapped and untapped ions in a double layer is also investigated theoretically and numerically.

  9. Flexible Mixed-Potential-Type (MPT) NO₂ Sensor Based on An Ultra-Thin Ceramic Film.

    Science.gov (United States)

    You, Rui; Jing, Gaoshan; Yu, Hongyan; Cui, Tianhong

    2017-07-29

    A novel flexible mixed-potential-type (MPT) sensor was designed and fabricated for NO₂ detection from 0 to 500 ppm at 200 °C. An ultra-thin Y₂O₃-doped ZrO₂ (YSZ) ceramic film 20 µm thick was sandwiched between a heating electrode and reference/sensing electrodes. The heating electrode was fabricated by a conventional lift-off process, while the porous reference and the sensing electrodes were fabricated by a two-step patterning method using shadow masks. The sensor's sensitivity is achieved as 58.4 mV/decade at the working temperature of 200 °C, as well as a detection limit of 26.7 ppm and small response time of less than 10 s at 200 ppm. Additionally, the flexible MPT sensor demonstrates superior mechanical stability after bending over 50 times due to the mechanical stability of the YSZ ceramic film. This simply structured, but highly reliable flexible MPT NO₂ sensor may lead to wide application in the automobile industry for vehicle emission systems to reduce NO₂ emissions and improve fuel efficiency.

  10. Proton probing of ultra-thin foil dynamics in high intensity regime

    Science.gov (United States)

    Prasad, Rajendra; Aktan, Esin; Aurand, Bastian; Cerchez, Mirela; Willi, Oswald

    2017-10-01

    The field of laser driven ion acceleration has been enriched significantly over the past decade, thanks to the advanced laser technologies. Already, from 100s TW class systems, laser driven sources of particles and radiations are being considered in number of potential applications in science and medicine due to their unique properties. New physical effects unearthed at these systems may help understand and conduct successful experiments at several PW class multi-beam facilities with high rep rate systems, e.g. ELI. Here we present the first experimental results on ultra-thin foil dynamics irradiated by an ultra-high intensity (1020 W/cm2) , ultra-high contrast (10-12) laser pulse at ARCTURUS laser facility at HHU Duesseldorf. By employing the elegant proton probing technique it is observed that for the circular polarization of laser light, a 100nm thin target is pushed forward as a compressed layer due to the radiation pressure of light. Whereas, the linear polarization seems to decompress the target drastically. 2D particle-in-cell simulations corroborate the experimental findings. Our results confirm the previous simulation studies investigating the fundamental role played by light polarization, finite focus spot size effect and eventually electron heating including the oblique incidence at the target edges.

  11. Formation of a highly doped ultra-thin amorphous carbon layer by ion bombardment of graphene

    Science.gov (United States)

    Piotr Michałowski, Paweł; Pasternak, Iwona; Ciepielewski, Paweł; Guinea, Francisco; Strupiński, Włodek

    2018-07-01

    Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 1014 atoms cm‑2) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

  12. Facile design of ultra-thin anodic aluminum oxide membranes for the fabrication of plasmonic nanoarrays

    Science.gov (United States)

    Hao, Qi; Huang, Hao; Fan, Xingce; Hou, Xiangyu; Yin, Yin; Li, Wan; Si, Lifang; Nan, Haiyan; Wang, Huaiyu; Mei, Yongfeng; Qiu, Teng; Chu, Paul K.

    2017-03-01

    Ultra-thin anodic aluminum oxide (AAO) membranes are efficient templates for the fabrication of patterned nanostructures. Herein, a three-step etching method to control the morphology of AAO is described. The morphological evolution of the AAO during phosphoric acid etching is systematically investigated and a nonlinear growth mechanism during unsteady-state anodization is revealed. The thickness of the AAO can be quantitatively controlled from ˜100 nm to several micrometers while maintaining the tunablity of the pore diameter. The AAO membranes are robust and readily transferable to different types of substrates to prepare patterned plasmonic nanoarrays such as nanoislands, nanoclusters, ultra-small nanodots, and core-satellite superstructures. The localized surface plasmon resonance from these nanostructures can be easily tuned by adjusting the morphology of the AAO template. The custom AAO template provides a platform for the fabrication of low-cost and large-scale functional nanoarrays suitable for fundamental studies as well as applications including biochemical sensing, imaging, photocatalysis, and photovoltaics.

  13. Self organized striping in ultra thin polymer films near melt: An investigation using Monte Carlo simulation

    Science.gov (United States)

    Singh, Satya Pal

    2018-05-01

    This paper work presents the results of Monte Carlo simulation performed for ultra thin short chained polymer films near melt, under strong confinement. Thin polymer films get ruptured when annealed above their glass transition temperatures. The pattern formations are generally explained on the basis of spinodal mechanism, if the thickness of the film is of the order of few tens of nanometers i.e. film seems to tear apart in strips. The free end segments of the chains are more dynamic and coalescence into one another. This process seems to dominate over the spinodal waves resulting into a different type of dynamics. Polymer chains with 30 monomers are taken. 160, 200 and 240 chains are taken for three different cases of the studies. The three cases correspond to three different thickness of the films with 8, 10 and 12 layers of chains along direction perpendicular to the confining substrates. The bottom surface has affinity to monomers, whereas the upper surface has hard wall interaction with the monomers. Different time micrographs of the films are plotted along with density distributions of the monomers to explore the process.

  14. Oxygen-enabled control of Dzyaloshinskii-Moriya Interaction in ultra-thin magnetic films

    KAUST Repository

    Belabbes, Abderrezak

    2016-04-22

    The search for chiral magnetic textures in systems lacking spatial inversion symmetry has attracted a massive amount of interest in the recent years with the real space observation of novel exotic magnetic phases such as skyrmions lattices, but also domain walls and spin spirals with a defined chirality. The electrical control of these textures offers thrilling perspectives in terms of fast and robust ultrahigh density data manipulation. A powerful ingredient commonly used to stabilize chiral magnetic states is the so-called Dzyaloshinskii-Moriya interaction (DMI) arising from spin-orbit coupling in inversion asymmetric magnets. Such a large antisymmetric exchange has been obtained at interfaces between heavy metals and transition metal ferromagnets, resulting in spin spirals and nanoskyrmion lattices. Here, using relativistic first-principles calculations, we demonstrate that the magnitude and sign of DMI can be entirely controlled by tuning the oxygen coverage of the magnetic film, therefore enabling the smart design of chiral magnetism in ultra-thin films. We anticipate that these results extend to other electronegative ions and suggest the possibility of electrical tuning of exotic magnetic phases.

  15. Dual-side and three-dimensional microelectrode arrays fabricated from ultra-thin silicon substrates

    International Nuclear Information System (INIS)

    Du, Jiangang; Masmanidis, Sotiris C; Roukes, Michael L

    2009-01-01

    A method for fabricating planar implantable microelectrode arrays was demonstrated using a process that relied on ultra-thin silicon substrates, which ranged in thickness from 25 to 50 µm. The challenge of handling these fragile materials was met via a temporary substrate support mechanism. In order to compensate for putative electrical shielding of extracellular neuronal fields, separately addressable electrode arrays were defined on each side of the silicon device. Deep reactive ion etching was employed to create sharp implantable shafts with lengths of up to 5 mm. The devices were flip-chip bonded onto printed circuit boards (PCBs) by means of an anisotropic conductive adhesive film. This scalable assembly technique enabled three-dimensional (3D) integration through formation of stacks of multiple silicon and PCB layers. Simulations and measurements of microelectrode noise appear to suggest that low impedance surfaces, which could be formed by electrodeposition of gold or other materials, are required to ensure an optimal signal-to-noise ratio as well a low level of interchannel crosstalk

  16. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    KAUST Repository

    Ghoneim, Mohamed T.; Fahad, Hossain M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Sevilla, Galo T.; Alfaraj, Nasir; Lizardo, Ernesto B.; Hussain, Muhammad Mustafa

    2015-01-01

    In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  17. Analysis of switching characteristics for negative capacitance ultra-thin-body germanium-on-insulator MOSFETs

    Science.gov (United States)

    Pi-Ho Hu, Vita; Chiu, Pin-Chieh

    2018-04-01

    The impact of device parameters on the switching characteristics of negative capacitance ultra-thin-body (UTB) germanium-on-insulator (NC-GeOI) MOSFETs is analyzed. NC-GeOI MOSFETs with smaller gate length (L g), EOT, and buried oxide thickness (T box) and thicker ferroelectric layer thickness (T FE) exhibit larger subthreshold swing improvements over GeOI MOSFETs due to better capacitance matching. Compared with GeOI MOSFETs, NC-GeOI MOSFETs exhibit better switching time due to improvements in effective drive current (I eff) and subthreshold swing. NC-GeOI MOSFET exhibits larger ST improvements at V dd = 0.3 V (-82.9%) than at V dd = 0.86 V (-9.7%), because NC-GeOI MOSFET shows 18.2 times higher I eff than the GeOI MOSFET at V dd = 0.3 V, while 2.5 times higher I eff at V dd = 0.86 V. This work provides the device design guideline of NC-GeOI MOSFETs for ultra-low power applications.

  18. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-12-11

    In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  19. Ultrasonic force microscopy: detection and imaging of ultra-thin molecular domains.

    Science.gov (United States)

    Dinelli, Franco; Albonetti, Cristiano; Kolosov, Oleg V

    2011-03-01

    The analysis of the formation of ultra-thin organic films is a very important issue. In fact, it is known that the properties of organic light emitting diodes and field effect transistors are strongly affected by the early growth stages. For instance, in the case of sexithiophene, the presence of domains made of molecules with the backbone parallel to the substrate surface has been indirectly evidenced by photoluminescence spectroscopy and confocal microscopy. On the contrary, conventional scanning force microscopy both in contact and intermittent contact modes have failed to detect such domains. In this paper, we show that Ultrasonic Force Microscopy (UFM), sensitive to nanomechanical properties, allows one to directly identify the structure of sub-monolayer thick films. Sexithiophene flat domains have been imaged for the first time with nanometer scale spatial resolution. A comparison with lateral force and intermittent contact modes has been carried out in order to explain the origins of the UFM contrast and its advantages. In particular, it indicates that UFM is highly suitable for investigations where high sensitivity to material properties, low specimen damage and high spatial resolution are required. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Improved DC and RF performance of InAlAs/InGaAs InP based HEMTs using ultra-thin 15 nm ALD-Al2O3 surface passivation

    Science.gov (United States)

    Asif, Muhammad; Chen, Chen; Peng, Ding; Xi, Wang; Zhi, Jin

    2018-04-01

    Owing to the great influence of surface passivation on DC and RF performance of InP-based HEMTs, the DC and RF performance of InAlAs/InGaAs InP HEMTs were studied before and after passivation, using an ultra-thin 15 nm atomic layer deposition Al2O3 layer. Increase in Cgs and Cgd was significantly limited by scaling the thickness of the Al2O3 layer. For verification, an analytical small-signal equivalent circuit model was developed. A significant increase in maximum transconductance (gm) up to 1150 mS/mm, drain current (IDS) up to 820 mA/mm and fmax up to 369.7 GHz was observed, after passivation. Good agreement was obtained between the measured and the simulated results. This shows that the RF performance of InP-based HEMTs can be improved by using an ultra-thin ALD-Al2O3 surface passivation.

  1. Effect of thermal cycling on the microstructure of a directionally solidified Fe, Cr, Al-TaC eutectic alloy

    Science.gov (United States)

    Harf, F. H.; Tewari, S. N.

    1977-01-01

    Cylindrical bars (1.2 cm diameter) of Fe-13.6Cr-3.7Al-9TaC (wt %) eutectic alloy were directionally solidified in a modified Bridgman type furnace at 1 cm/h. The alloy microstructure consisted of aligned TaC fibers imbedded in a bcc Fe-Cr-Al matrix. Specimens of the alloy were thermally cycled from 1100 to 425 C in a burner rig. The effects of 1800 thermal cycles on the microstructure was examined by scanning electron microscopy, revealing a zig-zag shape of TaC fibers aligned parallel to the growth direction. The mechanism of carbide solution and reprecipitation on the (111) easy growth planes, suggested previously to account for the development of irregular serrations in Co-Cr-Ni matrix alloys, is believed to be responsible for these zig-zag surfaces.

  2. Lithium-ion storage capacitors achieved by CVD graphene/TaC/Ta-wires and carbon hollow spheres

    International Nuclear Information System (INIS)

    Zhao, Liwei; Li, Hongji; Li, Mingji; Xu, Sheng; Li, Cuiping; Qu, Changqing; Zhang, Lijun; Yang, Baohe

    2016-01-01

    Highlights: • Graphene/TaC/Ta wire electrode was prepared by CVD. • Carbon hollow spheres as a solid electrolyte were prepared by hydrothermal. • Specific capacitance of assembled capacitor reached 593 F g −1 at 10 A g −1 . • The capacitor provided high energy and power densities (132 W h kg −1 /3.17 kW kg −1 ). • The hybrid capacitor also exhibited a high stability during long endurance tests. - Abstract: Lithium-ion storage capacitors were assembled using graphene/tantalum carbide/tantalum wire electrodes and carbon hollow spheres as electrolyte. The graphene/tantalum carbide layers were prepared by electron-assisted hot filament chemical vapor deposition; the carbon hollow spheres were synthesized by hydrothermal reaction and pyrolysis treatment. The specific capacitance of the capacitor was 593 F g −1 at a current density of 10 A g −1 . The capacitor showed excellent cycling stability, retaining 91.2% of its initial capacitance after 8000 cycles. Moreover, the capacitor provided a high specific energy density of 132 W h kg −1 at a high power density of 3.17 kW kg −1 . The high energy density is attributed to the widened operation window ranging from 0 to 3.0 V. The graphene layer of the electrode and carbon hollow spheres in electrolyte synergistic affect influence on the electrochemical performance of the capacitor are discussed. In addition, the use of a low-cost lithium salt, lithium chloride, is also featured in this paper.

  3. Ion-beam mixed ultra-thin cobalt suicide (CoSi2) films by cobalt sputtering and rapid thermal annealing

    Science.gov (United States)

    Kal, S.; Kasko, I.; Ryssel, H.

    1995-10-01

    The influence of ion-beam mixing on ultra-thin cobalt silicide (CoSi2) formation was investigated by characterizing the ion-beam mixed and unmixed CoSi2 films. A Ge+ ion-implantation through the Co film prior to silicidation causes an interface mixing of the cobalt film with the silicon substrate and results in improved silicide-to-silicon interface roughness. Rapid thermal annealing was used to form Ge+ ion mixed and unmixed thin CoSi2 layer from 10 nm sputter deposited Co film. The silicide films were characterized by secondary neutral mass spectroscopy, x-ray diffraction, tunneling electron microscopy (TEM), Rutherford backscattering, and sheet resistance measurements. The experi-mental results indicate that the final rapid thermal annealing temperature should not exceed 800°C for thin (micrographs of the ion-beam mixed and unmixed CoSi2 films reveals that Ge+ ion mixing (45 keV, 1 × 1015 cm-2) produces homogeneous silicide with smooth silicide-to-silicon interface.

  4. Ultra-thin MoS2 coated Ag@Si nanosphere arrays as efficient and stable photocathode for solar-driven hydrogen production.

    Science.gov (United States)

    Zhou, Qingwei; Su, Shaoqiang; Hu, Die; Lin, Lin; Yan, Zhibo; Gao, Xingsen; Zhang, Zhang; Liu, Junming

    2018-01-02

    Solar-driven photoelectrochemical (PEC) water splitting has recently attracted much attention. Silicon (Si) is an ideal light absorber for solar energy conversion. However, the poor stability and inefficient surface catalysis of Si photocathode for hydrogen evolution reaction (HER) have been remained as the key challenges. Alternatively, MoS2 has been reported to exhibit the excellent catalysis performance if sufficient active sites for the HER are available. Here, ultra-thin MoS2 nanoflakes are directly synthesized to coat on the arrays of Ag-core Si-shell nanospheres (Ag@Si NSs) using the chemical vapor deposition (CVD). Due to the high surface area ratio and large curvature of these NSs, the as-grown MoS2 nanoflakes can accommodate more active sites. Meanwhile, the high-quality coating of MoS2 nanoflakes on the Ag@Si NSs protects the photocathode from damage during the PEC reaction. A high efficiency with a photocurrent of 33.3 mA cm-2 at a voltage of -0.4 V vs. the reversible hydrogen electrode is obtained. The as-prepared nanostructure as hydrogen photocathode is evidenced to have high stability over 12 hour PEC performance. This work opens opportunities for composite photocathode with high activity and stability using cheap and stable co-catalysts. © 2017 IOP Publishing Ltd.

  5. Improved integration of ultra-thin high-k dielectrics in few-layer MoS2 FET by remote forming gas plasma pretreatment

    Science.gov (United States)

    Wang, Xiao; Zhang, Tian-Bao; Yang, Wen; Zhu, Hao; Chen, Lin; Sun, Qing-Qing; Zhang, David Wei

    2017-01-01

    The effective and high-quality integration of high-k dielectrics on two-dimensional (2D) crystals is essential to the device structure engineering and performance improvement of field-effect transistor (FET) based on the 2D semiconductors. We report a 2D MoS2 transistor with ultra-thin Al2O3 top-gate dielectric (6.1 nm) and extremely low leakage current. Remote forming gas plasma pretreatment was carried out prior to the atomic layer deposition, providing nucleation sites with the physically adsorbed ions on the MoS2 surface. The top gate MoS2 FET exhibited excellent electrical performance, including high on/off current ratio over 109, subthreshold swing of 85 mV/decade and field-effect mobility of 45.03 cm2/V s. Top gate leakage current less than 0.08 pA/μm2 at 4 MV/cm has been obtained, which is the smallest compared with the reported top-gated MoS2 transistors. Such an optimized integration of high-k dielectric in 2D semiconductor FET with enhanced performance is very attractive, and it paves the way towards the realization of more advanced 2D nanoelectronic devices and integrated circuits.

  6. Aging of oxygen and hydrogen plasma discharge treated a-C:H and ta-C coatings

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, Svenja [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); BMW Group, Hufelandstraße 4, 80788 Munich (Germany); Schulze, Marcus [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); Morasch, Jan [Institute of Materials Science, Technische Universität Darmstadt, Surface Science Division, Jovanka-Bonschits-Straße 2, 64287 Darmstadt (Germany); Hesse, Sabine [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); Hussein, Laith [Eduard-Zintl-Institut, Department of Chemistry, Technische Universität Darmstadt, Alarich-Weiss-Str. 12, 64287, Darmstadt (Germany); Krell, Lisa; Schnagl, Johann [BMW Group, Hufelandstraße 4, 80788 Munich (Germany); Stark, Robert W. [Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt (Germany); and others

    2016-05-15

    Highlights: • The water CA of O{sub 2} and H{sub 2} plasma treated a-C:H and ta-C changes from hydrophillic to hydrophobic on aging. • XPS study indicates that the decrease in surface energy of plasma treated a-C:H and ta-C could be due to adsorption of organic component from air. • The COFLFM of O{sub 2} and H{sub 2} plasma treated a-C:H and ta-C decreased upon aging. • The COF of glycerol lubricated ta-C showed no sign of change upon aging. - Abstract: Surface modification with gas plasma is an efficient and easy way to improve the surface energy and the tribological behavior of diamond-like carbon (DLC) coatings, e.g., in biomedical implants or as protective coatings. However, the long-term performance of the plasma treated DLC coatings is not fully clear. We thus studied the long-term stability of two kinds of DLC coatings, namely (a) hydrogenated amorphous carbon (a-C:H) and (b) tetrahedral amorphous carbon (ta-C) treated at different radio frequency (RF) power and time of oxygen (O{sub 2}) and hydrogen (H{sub 2}) plasma. Their surface properties, e.g. surface wettability, structure and tribological behavior, were studied at regular intervals for a period of two months using contact angle goniometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), lateral force microscopy (LFM) and ball on disc apparatus. The surface energy of both the coatings decreased upon aging. The higher the RF power and time of treatment, the higher was the hydrophobicity upon aging. XPS analysis showed that the increase in hydrophobicity could be due to adsorption of unavoidable volatile organic components in the atmosphere. The H{sub 2} plasma treated ta-C was capable of rearranging its structural bonds upon aging. The nano-friction measurements by LFM showed that the coefficient of friction of plasma treated a-C:H and ta-C decreased upon aging. The results indicate that the surface properties of plasma treated a‐C:H and ta‐C are not stable on long-term and are

  7. Kinetics of high-temperature oxidation of (Ti,Ta)(C,N)-based cermets

    International Nuclear Information System (INIS)

    Chicardi, E.; Córdoba, J.M.; Gotor, F.J.

    2016-01-01

    Highlights: • The kinetic of high-temperature oxidation of (Ti,Ta)(C,N)-Co cermets was studied. • A parabolic oxidation kinetic was determined in cermets between 700 °C and 1200 °C. • This parabolic kinetic behaviour is due to the existence of a protective layer. • The protective layer formed was a complex Ti_xTa_1_−_xO_2 oxide with rutile structure. • The oxidation rate is controlled by the Ti and O_2 diffusion through the Ti_xTa_1_−_xO_2. - Abstract: The kinetics of the high-temperature oxidation of titanium–tantalum carbonitride-based cermets with different Ti/Ta ratios was studied. Isothermal oxidation tests were conducted under static air for 48 h at temperatures between 700 °C and 1200 °C. The oxidation satisfied the parabolic kinetics, characteristic of the existence of a protective oxide layer. The apparent activation energy suggests the rate-controlling process during oxidation is the simultaneous inward and outward diffusion of oxygen and titanium, respectively, through the formed protective layer, consisting mainly of a rutile phase. A higher Ta(V) content in the rutile decreased the oxygen diffusivity due to the reduction of oxygen vacancy concentration.

  8. High temperature oxidation resistance of (Ti,Ta)(C,N)-based cermets

    International Nuclear Information System (INIS)

    Chicardi, E.; Córdoba, J.M.; Gotor, F.J.

    2016-01-01

    Highlights: • Cermets based on (Ti,Ta)(C,N) were oxidized in air between 800 and 1100 °C for 48 h. • The substitution of Ti by Ta resulted in a high resistance to oxidation. • A protective layer of cobalt titanates at the surface of cermets was observed. • A rutile phase in which some Ti"4"+ are replaced by Ta"5"+ was detected. • This replacement decelerated the oxygen diffusion into the cermets. - Abstract: Cermets based on titanium–tantalum carbonitride were oxidized in static air between 800 °C and 1100 °C for 48 h. The thermogravimetric and microstructural study showed an outstanding reduction in the oxidation of more than 90% when the Ta content was increased. In cermets with low Ta content, the formation of a thin CoO/Co_3O_4 outer layer tends to disappear by reacting with the underlying rutile phase, which emerges at the surface. However, in cermets with higher Ta content, the formation of an external titanate layer, observed even at a low temperature, appears to prevent the oxygen diffusion and the oxidation progression.

  9. Ultra-thin films of polysilsesquioxanes possessing 3-methacryloxypropyl groups as gate insulator for organic field-effect transistors

    International Nuclear Information System (INIS)

    Nakahara, Yoshio; Kawa, Haruna; Yoshiki, Jun; Kumei, Maki; Yamamoto, Hiroyuki; Oi, Fumio; Yamakado, Hideo; Fukuda, Hisashi; Kimura, Keiichi

    2012-01-01

    Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups as an organic moiety of the side chain were synthesized by sol–gel condensation copolymerization of the corresponding trialkoxysilanes. The ultra-thin PSQ film with a radical initiator and a cross-linking agent was prepared by a spin-coating method, and the film was cured integrally at low temperatures of less than 120 °C through two different kinds of polymeric reactions, which were radical polymerization of vinyl groups and sol–gel condensation polymerization of terminated silanol and alkoxy groups. The obtained PSQ film showed the almost perfect solubilization resistance to acetone, which is a good solvent of PSQ before polymerization. It became clear by atomic force microscopy observation that the surface of the PSQ film was very smooth at a nano-meter level. Furthermore, pentacene-based organic field-effect transistor (OFET) with the PSQ film as a gate insulator showed typical p-channel enhancement mode operation characteristics and therefore the ultra-thin PSQ film has the potential to be applicable for solution-processed OFET systems. - Highlights: ► Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups were synthesized. ► The ultra-thin PSQ film could be cured at low temperatures of less than 120 °C. ► The PSQ film showed the almost perfect solubilization resistance to organic solvent. ► The surface of the PSQ film was very smooth at a nano-meter level. ► Pentacene-based organic field-effect transistor with the PSQ film was fabricated.

  10. Ultra-thin films of polysilsesquioxanes possessing 3-methacryloxypropyl groups as gate insulator for organic field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Nakahara, Yoshio; Kawa, Haruna [Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510 (Japan); Yoshiki, Jun [Division of Information and Electronic Engineering, Faculty of Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585 (Japan); Kumei, Maki; Yamamoto, Hiroyuki; Oi, Fumio [Konishi Chemical IND. Co., LTD., 3-4-77 Kozaika, Wakayama 641-0007 (Japan); Yamakado, Hideo [Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510 (Japan); Fukuda, Hisashi [Division of Engineering for Composite Functions, Faculty of Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585 (Japan); Kimura, Keiichi, E-mail: kkimura@center.wakayama-u.ac.jp [Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakae-dani, Wakayama 640-8510 (Japan)

    2012-10-01

    Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups as an organic moiety of the side chain were synthesized by sol-gel condensation copolymerization of the corresponding trialkoxysilanes. The ultra-thin PSQ film with a radical initiator and a cross-linking agent was prepared by a spin-coating method, and the film was cured integrally at low temperatures of less than 120 Degree-Sign C through two different kinds of polymeric reactions, which were radical polymerization of vinyl groups and sol-gel condensation polymerization of terminated silanol and alkoxy groups. The obtained PSQ film showed the almost perfect solubilization resistance to acetone, which is a good solvent of PSQ before polymerization. It became clear by atomic force microscopy observation that the surface of the PSQ film was very smooth at a nano-meter level. Furthermore, pentacene-based organic field-effect transistor (OFET) with the PSQ film as a gate insulator showed typical p-channel enhancement mode operation characteristics and therefore the ultra-thin PSQ film has the potential to be applicable for solution-processed OFET systems. - Highlights: Black-Right-Pointing-Pointer Polysilsesquioxanes (PSQs) possessing 3-methacryloxypropyl groups were synthesized. Black-Right-Pointing-Pointer The ultra-thin PSQ film could be cured at low temperatures of less than 120 Degree-Sign C. Black-Right-Pointing-Pointer The PSQ film showed the almost perfect solubilization resistance to organic solvent. Black-Right-Pointing-Pointer The surface of the PSQ film was very smooth at a nano-meter level. Black-Right-Pointing-Pointer Pentacene-based organic field-effect transistor with the PSQ film was fabricated.

  11. Comment on 'Extrinsic versus intrinsic ferroelectric switching: experimental investigations using ultra-thin PVDF Langmuir-Blodgett films'

    International Nuclear Information System (INIS)

    Naber, R C G; Blom, P W M; Leeuw, D M de

    2006-01-01

    Previous work on ultra-thin P(VDF-TrFE) Langmuir-Blodgett films has indicated a transition from extrinsic to intrinsic ferroelectric switching. The lack of several key features of intrinsic switching in the experimental work reported by Kliem et al argues against intrinsic switching. In this Comment we discuss two published papers and new experimental results that support a lack of intrinsic switching and point to the conclusion that the thickness dependence of the Langmuir-Blodgett films is due to the influence of the electrode interfaces. (comment)

  12. Foldover, quasi-periodicity, spin-wave instabilities in ultra-thin films subject to RF fields

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy)]. E-mail: mdaquino@unina.it; Bertotti, G. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Turin (Italy); Serpico, C. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD 20742 (United States); Bonin, R. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Turin (Italy); Guida, G. [Department of Electrical Engineering, University of Napoli ' Federico II' , Naples I-80125 (Italy)

    2007-09-15

    We study magnetization dynamics in a uniaxial ultra-thin ferromagnetic disk subject to spatially uniform microwave external fields. The rotational invariance of the system is such that the only admissible spatially uniform steady states are periodic (P-modes) and quasi-periodic (Q-modes) modes. The stability of P-modes versus spatially uniform and nonuniform perturbations is studied by using spin-wave analysis and the instability diagram for all possible P-modes is computed. The predictions of the spin-wave analysis are compared with micromagnetic simulations.

  13. Ultra-thin Glass Film Coated with Graphene: A New Material for Spontaneous Emission Enhancement of Quantum Emitter

    Institute of Scientific and Technical Information of China (English)

    Lu Sun; Chun Jiang

    2015-01-01

    We propose an ultra-thin glass film coated with graphene as a new kind of surrounding material which can greatly enhance spontaneous emission rate(SER) of dipole emitter embedded in it. With properly designed parameters,numerical results show that SER-enhanced factors as high as 1.286 9 106 can be achieved. The influences of glass film thickness and chemical potential/doping level of graphene on spontaneous emission enhancement are also studied in this paper. A comparison is made between graphene and other coating materials such as gold and silver to see their performances in SER enhancement.

  14. The kinetics of dewetting ultra-thin Si layers from silicon dioxide

    International Nuclear Information System (INIS)

    Aouassa, M; Favre, L; Ronda, A; Berbezier, I; Maaref, H

    2012-01-01

    In this study, we investigate the kinetically driven dewetting of ultra-thin silicon films on silicon oxide substrate under ultra-high vacuum, at temperatures where oxide desorption and silicon lost could be ruled out. We show that in ultra-clean experimental conditions, the three different regimes of dewetting, namely (i) nucleation of holes, (ii) film retraction and (iii) coalescence of holes, can be quantitatively measured as a function of temperature, time and thickness. For a nominal flat clean sample these three regimes co-exist during the film retraction until complete dewetting. To discriminate their roles in the kinetics of dewetting, we have compared the dewetting evolution of flat unpatterned crystalline silicon layers (homogeneous dewetting), patterned crystalline silicon layers (heterogeneous dewetting) and amorphous silicon layers (crystallization-induced dewetting). The first regime (nucleation) is described by a breaking time which follows an exponential evolution with temperature with an activation energy E H ∼ 3.2 eV. The second regime (retraction) is controlled by surface diffusion of matter from the edges of the holes. It involves a very fast redistribution of matter onto the flat Si layer, which prevents the formation of a rim on the edges of the holes during both heterogeneous and homogeneous dewetting. The time evolution of the linear dewetting front measured during heterogeneous dewetting follows a characteristic power law x ∼ t 0.45 consistent with a surface diffusion-limited mechanism. It also evolves as x ∼ h -1 as expected from mass conservation in the absence of thickened rim. When the surface energy is isotropic (during dewetting of amorphous Si) the dynamics of dewetting is considerably modified: firstly, there is no measurable breaking time; secondly, the speed of dewetting is two orders of magnitude larger than for crystalline Si; and thirdly, the activation energy of dewetting is much smaller due to the different driving

  15. Measured Whole-House Performance of TaC Studios Test Home

    Energy Technology Data Exchange (ETDEWEB)

    Butler, T. [Partnership for Home Innovation (PHI), Upper Marlboro, MD (United States). Southface Energy Inst.; Curtis, O. [Partnership for Home Innovation (PHI), Upper Marlboro, MD (United States). Southface Energy Inst.; Stephenson, R. [Partnership for Home Innovation (PHI), Upper Marlboro, MD (United States). Southface Energy Inst.

    2013-12-01

    As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta-based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA in the mixed humid climate. This home serves as a residence and home office for the firm's owners, as well as a demonstration of their design approach topotential and current clients. Southface believes the home demonstrates current best practices for the mixed-humid climate, including a building envelope featuring advanced air sealing details and low density spray foam insulation, glazing that exceeds ENERGY STAR requirements, and a high performance heating and cooling system. Construction quality and execution was a high priority for TaCStudios and was ensured by a third party review process. Post-construction testing showed that the project met stated goals for envelope performance, an air infiltration rate of 2.15 ACH50. The homeowners wished to further validate whole house energy savings through the project's involvement with Building America and this long-term monitoring effort. As a Building America test home, this homewas evaluated to detail whole house energy use, end use loads, and the efficiency and operation of the ground source heat pump and associated systems. Given that the home includes many non-typical end use loads including a home office, pool, landscape water feature, and other luxury features not accounted for in Building America modeling tools, these end uses were separately monitored todetermine their impact on overall energy consumption.

  16. The effects of ultra-thin cerium fluoride film as the anode buffer layer on the electrical characteristics of organic light emitting diodes

    Science.gov (United States)

    Lu, Hsin-Wei; Tsai, Cheng-Che; Hong, Cheng-Shong; Kao, Po-Ching; Juang, Yung-Der; Chu, Sheng-Yuan

    2016-11-01

    In this study, the efficiency of organic light-emitting diodes (OLEDs) was enhanced by depositing a CeF3film as an ultra-thin buffer layer between the indium tin oxide (ITO) electrode and α-naphthylphenylbiphenyldiamine (NPB) hole transport layer, with the structure configuration ITO/CeF3 (0.5, 1, and 1.5 nm)/α-naphthylphenylbiphenyl diamine (NPB) (40 nm)/tris(8-hydroxyquinoline) aluminum (Alq3) (60 nm)/lithium fluoride (LiF) (1 nm)/Al (150 nm). The enhancement mechanism was systematically investigated via several approaches. The X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy results revealed the formation of the UV-ozone treated CeF3 film. The work function increased from 4.8 eV (standard ITO electrode) to 5.22 eV (0.5-nm-thick UV-ozone treated CeF3 film deposited on the ITO electrode). The surface roughness of the UV-ozone treated CeF3 film was smoother than that of the standard ITO electrode. Further, the UV-ozone treated CeF3 film increased both the surface energy and polarity, as determined from contact angle measurements. In addition, admittance spectroscopy measurements showed an increased capacitance and conductance of the OLEDs. Accordingly, the turn-on voltage decreased from 4.2 V to 3.6 V at 1 mA/cm2, the luminance increased from 7588 cd/m2 to 24760 cd/m2, and the current efficiency increased from 3.2 cd/A to 3.8 cd/A when the 0.5-nm-thick UV-ozone treated CeF3 film was inserted into the OLEDs.

  17. Anomalous aging and strain induced time dependent phenomena in ultra-thin La0.65Ca0.35MnO3 films

    International Nuclear Information System (INIS)

    Egilmez, M.; Saber, M.M.; Abdelhadi, M.; Chow, K.H.; Jung, J.

    2011-01-01

    We have shown that ultra-thin La 0.65 Ca 0.35 MnO 3 films exhibit strong metastable behavior. The resistance can vary with time significantly, suggesting that a state of dynamic phase separation exists whereby one phase grows at the expense of another. Physical properties associated with the metastable behavior have been investigated on the films grown on different substrates. We have found that ultra-thin films age much faster than the thicker counterparts and more interestingly the metastability in the resistance of these films enhanced when aged. -- Highlights: → Ultra-thin La 0.67 Ca 0.33 MnO 3 films exhibit metastable behavior. → Physical properties associated with metastable behavior have been investigated. → The metastability in resistance of the films enhanced when films are aged. → Relaxation rates were used as a relative measure the metastability. → The metastable behavior is sensitive to the strain state of the film.

  18. Effect of injection parameters on mechanical and physical properties of super ultra-thin wall propylene packaging by Taguchi method

    Science.gov (United States)

    Ginghtong, Thatchanok; Nakpathomkun, Natthapon; Pechyen, Chiravoot

    2018-06-01

    The parameters of the plastic injection molding process have been investigated for the manufacture of a 64 oz. ultra-thin polypropylene bucket. The 3 main parameters, such as injection speed, melting temperature, holding pressure, were investigated to study their effect on the physical appearance and compressive strength. The orthogonal array of Taguchi's L9 (33) was used to carry out the experimental plan. The physical properties were measured and the compressive strength was determined using linear regression analysis. The differential scanning calorimeter (DSC) was used to analyze the crystalline structure of the product. The optimization results show that the proposed approach can help engineers identify optimal process parameters and achieve competitive advantages of energy consumption and product quality. In addition, the injection molding of the product includes 24 mm of shot stroke, 1.47 mm position transfer, 268 rpm screw speed, injection speed 100 mm/s, 172 ton clamping force, 800 kgf holding pressure, 0.9 s holding time and 1.4 s cooling time, make the products in the shape and proportion of the product satisfactory. The parameters of influence are injection speed 71.07%, melting temperature 23.31% and holding pressure 5.62%, respectively. The compressive strength of the product was able to withstand a pressure of up to 839 N before the product became plastic. The low melting temperature was caused by the superior crystalline structure of the super-ultra-thin wall product which leads to a lower compressive strength.

  19. Surface modification of ultra thin PES-zeolite using thermal annealing to increase flux and rejection of produced water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kusworo, T. D., E-mail: tdkusworo@che.undip.ac.id; Widayat,; Pradini, A. W.; Armeli, Y. P. [Department of Chemical Engineering, University of Diponegoro Prof. Soedarto, Tembalang, Semarang, 50239, Phone/Fax : (024) 7460058 (Indonesia)

    2015-12-29

    Membrane technology is an alternative of water treatment based on filtration that is being developed. Surface Modification using heat treatment has been investigated to improve the performance of ultra thin PES-Zeolite nanocomposite membrane for produced water treatment from Pertamina Balongan. Two types of membranes with surface modification and without modification were prepared to study the effect of surface modification on its permeation properties. Asymmetric ultra thin PES-Zeolite nanocomposite membrane for produced water treatment was casted using the dry/wet phase inversion technique from dope solutions containing polyethersulfone, N-methyl-2-pyrrolidone (NMP) as a solvent and zeolite as a filler. Experimental results showed that the heat treatment at near glass transition temperature was increase the rejection of COD, Turbidity and ion Ca{sup 2+}. The better adherence of zeolite particles in the polymer matrix combined with formation of charge transfer complexes (CTCs) and cross-linking might be the main factors to enhance the percent of rejection. Field emission scanning electron microscopy (FESEM) micrographs showed that the selective layer and the substructure of PES-zeolite membrane became denser and more compact after the heat treatment. The FESEM micrographs also showed that the heat treatment was increased the adherence of zeolite particle and polymer. Membranes treated at 180 °C for 15 seconds indicated increase the rejection and small decrease in flux for produced water treatment.

  20. Sensitive thermal transitions of nanoscale polymer samples using the bimetallic effect: application to ultra-thin polythiophene.

    Science.gov (United States)

    Ahumada, O; Pérez-Madrigal, M M; Ramirez, J; Curcó, D; Esteves, C; Salvador-Matar, A; Luongo, G; Armelin, E; Puiggalí, J; Alemán, C

    2013-05-01

    A sensitive nanocalorimetric technology based on microcantilever sensors is presented. The technology, which combines very short response times with very small sample consumption, uses the bimetallic effect to detect thermal transitions. Specifically, abrupt variations in the Young's modulus and the thermal expansion coefficient produced by temperature changes have been employed to detect thermodynamic transitions. The technology has been used to determine the glass transition of poly(3-thiophene methyl acetate), a soluble semiconducting polymer with different nanotechnological applications. The glass transition temperature determined using microcantilevers coated with ultra-thin films of mass = 10(-13) g is 5.2 °C higher than that obtained using a conventional differential scanning calorimeter for bulk powder samples of mass = 5 × 10(-3) g. Atomistic molecular dynamics simulations on models that represent the bulk powder and the ultra-thin films have been carried out to provide understanding and rationalization of this feature. Simulations indicate that the film-air interface plays a crucial role in films with very small thickness, affecting both the organization of the molecular chains and the response of the molecules against the temperature.

  1. Synthesis of ultra-thin tellurium nanoflakes on textiles for high-performance flexible and wearable nanogenerators

    Energy Technology Data Exchange (ETDEWEB)

    He, Wen; Van Ngoc, Huynh; Qian, Yong Teng; Hwang, Jae Seok; Yan, Ya Ping [Department of Physics and Interdisciplinary Course of Physics and Chemistry, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon 16419, Gyeoggi-do (Korea, Republic of); Choi, Hongsoo [Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 711-873, Daegu (Korea, Republic of); Kang, Dae Joon, E-mail: djkang@skku.edu [Department of Physics and Interdisciplinary Course of Physics and Chemistry, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon 16419, Gyeoggi-do (Korea, Republic of)

    2017-01-15

    Highlights: • Ultra-thin tellurium (Te) nanoflakes were successfully grown on textile and used as an active piezoelectric material. • Te nanoflake nanogenerator device was systematically studied by bending and compressing test. • The ultra-high output power during compressing test can light up 10 LEDs without any external power source. • The device can offer a breakthrough in applying tellurium nanoflakes into high-performance flexible and wearable piezoelectric nanogenerator. - Abstract: We report that ultra-thin tellurium (Te) nanoflakes were successfully grown on a sample of a gold-coated textile, which then was used as an active piezoelectric material. An output voltage of 4 V and a current of 300 nA were obtained from the bending test under a driving frequency of 10 Hz. To test the practical applications, Te nanoflake nanogenerator (TFNG) device was attached to the subject’s arm, and mechanical energy was converted to electrical energy by means of periodic arm-bending motions. The optimized open-circuit voltage and short-circuit current density of approximately 125 V and 17 μA/cm{sup 2}, respectively, were observed when a TFNG device underwent a compression test with a compressive force of 8 N and driving frequency of 10 Hz. This high-power generation enabled the instantaneous powering of 10 green light-emitting diodes that shone without any assistance from an external power source.

  2. Transport properties of ultra-thin granular YBa2Cu3O7−δ nanobridges

    International Nuclear Information System (INIS)

    Bar, E.; Levi, D.; Koren, G.; Shaulov, A.; Yeshurun, Y.

    2014-01-01

    Highlights: • Nano bridges were patterned on laser ablated ultra-thin YBa 2 Cu 3 O 7 films. • Magneto-transport measurements reveal phenomena that are usually absent in the bulk. • Magnetoresistance (MR) oscillation point to effect of granularity. • Negative MR at low fields and negative MR slope at high fields were observed. • V-I curves exhibit voltage jumps at temperatures well below T c . - Abstract: Magneto-transport measurements in YBa 2 Cu 3 O 7 nanobridges, patterned on laser ablated ultra-thin films, reveal phenomena that are usually absent in the bulk of the material. These include broadening of the resistive transition, magnetoresistance oscillation, negative magnetoresistance at low fields, negative magnetoresistance slope at high fields, and V–I curves that exhibit voltage jumps at temperatures well below T c . These phenomena, attributed to the granular nature of the bridges, should be taken into account in any future attempts to utilize such bridges in technological applications

  3. Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

    Energy Technology Data Exchange (ETDEWEB)

    Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim, E-mail: ekarimi@uottawa.ca [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Boyd, Robert W. [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)

    2014-09-08

    Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

  4. Optical spin-to-orbital angular momentum conversion in ultra-thin metasurfaces with arbitrary topological charges

    International Nuclear Information System (INIS)

    Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim; Boyd, Robert W.

    2014-01-01

    Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.

  5. Effect of annealing on the composition and structure of TiC and TaC powders

    International Nuclear Information System (INIS)

    Vavrda, J.; Blazhikova, J.

    1979-01-01

    Effect of annealing (1300-2000 deg C) upon lattice parameters and composition of TiC and TaC powders has been investigated. It is established that the lowest deviation from stoichiometric composition of TiC and TaC is the result of annealing the samples, placed in graphite crucibles, in the medium of pure argon. It is shown, that the processes of decarbonizing and crystal defect formation produce decisive effect upon recrystallization of titanium and tantalum carbides. Using the methods of X-ray diffraction and scanning electron microscopy significant difference is detected in structural changes in TiC at high temperature heat treatment compared to recrystallization processes in metals. Singled out are the following stages of the process: carbide decarbonizing and arizing of lattice distortions connected with it; progressing disorientation of mosaic blocks, connected with the increase in stresses of the second kind and subsequent gragmentation of big crystals; relief in fragmentated crystals

  6. Aging of oxygen and hydrogen plasma discharge treated a-C:H and ta-C coatings

    Science.gov (United States)

    Bachmann, Svenja; Schulze, Marcus; Morasch, Jan; Hesse, Sabine; Hussein, Laith; Krell, Lisa; Schnagl, Johann; Stark, Robert W.; Narayan, Suman

    2016-05-01

    Surface modification with gas plasma is an efficient and easy way to improve the surface energy and the tribological behavior of diamond-like carbon (DLC) coatings, e.g., in biomedical implants or as protective coatings. However, the long-term performance of the plasma treated DLC coatings is not fully clear. We thus studied the long-term stability of two kinds of DLC coatings, namely (a) hydrogenated amorphous carbon (a-C:H) and (b) tetrahedral amorphous carbon (ta-C) treated at different radio frequency (RF) power and time of oxygen (O2) and hydrogen (H2) plasma. Their surface properties, e.g. surface wettability, structure and tribological behavior, were studied at regular intervals for a period of two months using contact angle goniometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), lateral force microscopy (LFM) and ball on disc apparatus. The surface energy of both the coatings decreased upon aging. The higher the RF power and time of treatment, the higher was the hydrophobicity upon aging. XPS analysis showed that the increase in hydrophobicity could be due to adsorption of unavoidable volatile organic components in the atmosphere. The H2 plasma treated ta-C was capable of rearranging its structural bonds upon aging. The nano-friction measurements by LFM showed that the coefficient of friction of plasma treated a-C:H and ta-C decreased upon aging. The results indicate that the surface properties of plasma treated a-C:H and ta-C are not stable on long-term and are influenced by the environmental conditions.

  7. Stoichiometry behavior of TaN, TaCN and TaC thin films produced by magnetron sputtering

    International Nuclear Information System (INIS)

    Vargas, M.; Castillo, H.A.; Restrepo-Parra, E.; De La Cruz, W.

    2013-01-01

    Thin films were synthesized in a magnetron sputtering system using a target of Ta with 99.99% purity and silicon substrates (1 1 1). The gases used for the film growth were (Ar + N 2 ), (Ar + CH 4 + N 2 ) and (Ar + CH 4 ) mixtures for TaN, TaCN and TaC, respectively. The substrate temperature increased from room temperature to 500 °C. The chemical composition and bonding configuration were examined using X-ray photoelectron spectroscopy (XPS), revealing Ta-N, Ta-C-N, Ta-C and C-C bonds. Moreover, the crystallographic structure was analyzed using X-ray diffraction (XRD), indicating the presence of (1 1 1) and (2 0 0) planes belonging to a face-centered cubic structure. The stoichiometry variation dependence on the CH 4 and N 2 flow was analyzed, and the influence of the substrate temperature on the coatings was investigated. Finally, scanning electron microscopy (SEM) was used to determine the evolution on the grain formation in the coatings as the substrate temperature increased.

  8. Stoichiometry behavior of TaN, TaCN and TaC thin films produced by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, M. [Centro de Nanociencia y Nanotecnología, Universidad Nacional Autónoma de México, A.P. 2681, C.P. 22860, Ensenada, B.C. (Mexico); Castillo, H.A. [Centro de Enseñanza Técnica y Superior, CETYS Universidad, Campus Tijuana, Tijuana, B.C. (Mexico); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Universidad Nacional de Colombia Sede Medellín Colombia, Facultad de Minas, Manizales (Colombia); De La Cruz, W. [Centro de Nanociencia y Nanotecnología, Universidad Nacional Autónoma de México, A.P. 2681, C.P. 22860, Ensenada, B.C. (Mexico)

    2013-08-15

    Thin films were synthesized in a magnetron sputtering system using a target of Ta with 99.99% purity and silicon substrates (1 1 1). The gases used for the film growth were (Ar + N{sub 2}), (Ar + CH{sub 4} + N{sub 2}) and (Ar + CH{sub 4}) mixtures for TaN, TaCN and TaC, respectively. The substrate temperature increased from room temperature to 500 °C. The chemical composition and bonding configuration were examined using X-ray photoelectron spectroscopy (XPS), revealing Ta-N, Ta-C-N, Ta-C and C-C bonds. Moreover, the crystallographic structure was analyzed using X-ray diffraction (XRD), indicating the presence of (1 1 1) and (2 0 0) planes belonging to a face-centered cubic structure. The stoichiometry variation dependence on the CH{sub 4} and N{sub 2} flow was analyzed, and the influence of the substrate temperature on the coatings was investigated. Finally, scanning electron microscopy (SEM) was used to determine the evolution on the grain formation in the coatings as the substrate temperature increased.

  9. Energy level alignment at the Si(1 1 1)/RCA–SiO2/copper(II) phthalocyanine ultra-thin film interface

    International Nuclear Information System (INIS)

    Krzywiecki, Maciej; Grządziel, Lucyna

    2014-01-01

    Graphical abstract: - Highlights: • The interface formation studies between CuPc and Si by photoemission methods. • Charge rearrangement detected at the inorganic/organic interface. • Existence of disordered/polarization layer at the initial stages of CuPc deposition. • Examined structures applicable for organic transistors development. - Abstract: The photoemission experimental techniques (i.e. ultraviolet photoelectron spectroscopy—UPS and X-ray photoelectron spectroscopy—XPS) were used to investigate the charge–rearrangement–related phenomena occuring at organic–inorganic semiconductor interface. Examined samples were copper phthalocyanine (CuPc) ultra-thin (up to 16 nm) layers deposited onto oxidized silicon Si(1 1 1) of n- and p-type of conductivity. The 1.3-nm-thick silicon oxide was prepared by means of RCA wet cleaning procedure. The analysis of the photoemission data (mainly UPS) suggested the existance of the polarization layer within first 3 nm of CuPc layer thickness. Basing on the UPS and XPS results the energy level diagrams of examined structures have been constructed. In present paper it is suggested that the existance of the polarization layer could be assigned to the disordered adsorption and continous molecular reorientation of the CuPc molecules during the interface formation process. In the terms of the lack of the charge transfer via substrate/organic overlayer interface and disordered adsorption the fluctuations of CuPc electronic parameters were detected. Moreover the ionization energy and the work function parameters of final CuPc layer were affected. The values were more consistent with those obtained for much thicker (over 500 nm) CuPc layers. Performed studies showed that contrary to CuPc layers deposited on native substrates (where the charge transfer via tunnelable oxide – determined as dipole effect – has been detected), the thicker RCA-prepared oxide seems to be non-tunnelable hence the possibility for Si(1 1 1

  10. The TDDB Characteristics of Ultra-Thin Gate Oxide MOS Capacitors under Constant Voltage Stress and Substrate Hot-Carrier Injection

    Directory of Open Access Journals (Sweden)

    Jingyu Shen

    2018-01-01

    Full Text Available The breakdown characteristics of ultra-thin gate oxide MOS capacitors fabricated in 65 nm CMOS technology under constant voltage stress and substrate hot-carrier injection are investigated. Compared to normal thick gate oxide, the degradation mechanism of time-dependent dielectric breakdown (TDDB of ultra-thin gate oxide is found to be different. It is found that the gate current (Ig of ultra-thin gate oxide MOS capacitor is more likely to be induced not only by Fowler-Nordheim (F-N tunneling electrons, but also by electrons surmounting barrier and penetrating electrons in the condition of constant voltage stress. Moreover it is shown that the time to breakdown (tbd under substrate hot-carrier injection is far less than that under constant voltage stress when the failure criterion is defined as a hard breakdown according to the experimental results. The TDDB mechanism of ultra-thin gate oxide will be detailed. The differences in TDDB characteristics of MOS capacitors induced by constant voltage stress and substrate hot-carrier injection will be also discussed.

  11. Effects of Cold Rolling Reduction and Initial Goss Grains Orientation on Texture Evolution and Magnetic Performance of Ultra-thin Grain-oriented Silicon Steel

    Directory of Open Access Journals (Sweden)

    LIANG Rui-yang

    2017-06-01

    Full Text Available The ultra-thin grain-oriented silicon steel strips with a thickness of 0.06-0.12mm were produced by one-step-rolling methods with different Goss-orientation of grain-oriented silicon steel sheets. The effect of cold rolling reduction and initial Goss-orientation of samples on texture evolution and magnetic performance of ultra-thin grain-oriented silicon steel strips was studied by EBSD. The result shows that with the increase of cold rolling reduction and decrease of strips thickness, the recrystallization texture is enhanced after annealing.When the cold rolling reduction is 70%,RD//〈001〉 recrystallization texture is the sharpest, and the magnetic performance is the best. The higher degree of Goss orientation in initial sample is, the better magnetic performance of ultra-thin grain-oriented silicon steel.Therefore, for producing an ultra-thin grain-oriented silicon steel with high performance, a material with a concentrated orientation of Goss grains can be used.

  12. Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

    KAUST Repository

    Onyegam, Emmanuel U.; Sarkar, Dabraj; Hilali, Mohamed M.; Saha, Sayan; Mathew, Leo; Rao, Rajesh A.; Smith, Ryan S.; Xu, Dewei; Jawarani, Dharmesh; Garcia, Ricardo; Ainom, Moses; Banerjee, Sanjay K.

    2014-01-01

    Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼ 25 μ m semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (Voc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in Voc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed. © 2014 AIP Publishing LLC.

  13. Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect Mg O(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhukovskii, Yuri F. [Institute for Solid State Physics, University of Latvia, Kengaraga str. 8, Riga LV-1063 (Latvia)]. E-mail: quantzh@latnet.lv; Fuks, David [Materials Engineering Department, Ben-Gurion University of the Negev, POB 653, Beer-Sheva IL-84105 (Israel); Kotomin, Eugene A. [Institute for Solid State Physics, University of Latvia, Kengaraga str. 8, Riga LV-1063 (Latvia); Dorfman, Simon [Department of Physics, Israel Institute of Technology-Technion, Haifa IL-32000 (Israel)

    2005-12-15

    Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nano electronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2a Cu superlattices on the regular Mg O(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the Daft-Gaga method, as implemented into the Crystal-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows US to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal density in clusters. We show that 3a cluster formation becomes predominant already at low Cu coverages, in agreement with the experiment.

  14. Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect Mg O(001) surface

    International Nuclear Information System (INIS)

    Zhukovskii, Yuri F.; Fuks, David; Kotomin, Eugene A.; Dorfman, Simon

    2005-01-01

    Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nano electronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2a Cu superlattices on the regular Mg O(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the Daft-Gaga method, as implemented into the Crystal-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows US to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal density in clusters. We show that 3a cluster formation becomes predominant already at low Cu coverages, in agreement with the experiment

  15. Congenital cheek teratoma with temporo-mandibular joint ankylosis managed with ultra-thin silicone sheet interpositional arthroplasty.

    Science.gov (United States)

    Bhatnagar, Ankur; Verma, Vinay Kumar; Purohit, Vishal

    2013-01-01

    Primary cheek teratomas are rare with joint ankylosis (TMJA). The fundamental aim in the treatment of TMJA is the successful surgical resection of ankylotic bone, prevention of recurrence, and aesthetic improvement by ensuring functional occlusion. Early treatment is necessary to promote proper growth and function of mandible and to facilitate the positive psychological development of child. Inter-positional arthroplasty with ultra-thin silicone sheet was performed. Advantages include short operative time, less foreign material in the joint space leading to negligible foreign body reactions and least chances of implant extrusion. Instead of excising a large bony segment, a thin silicone sheet was interposed and then sutured ensuring preservation of mandibular height. Aggressive post-operative physiotherapy with custom made dynamic jaw exerciser was used to prevent recurrence.

  16. Acoustic Phonons and Mechanical Properties of Ultra-Thin Porous Low-k Films: A Surface Brillouin Scattering Study

    Science.gov (United States)

    Zizka, J.; King, S.; Every, A.; Sooryakumar, R.

    2018-04-01

    To reduce the RC (resistance-capacitance) time delay of interconnects, a key development of the past 20 years has been the introduction of porous low-k dielectrics to replace the traditional use of SiO2. Moreover, in keeping pace with concomitant reduction in technology nodes, these low-k materials have reached thicknesses below 100 nm wherein the porosity becomes a significant fraction of the film volume. The large degree of porosity not only reduces mechanical strength of the dielectric layer but also renders a need for non-destructive approaches to measure the mechanical properties of such ultra-thin films within device configurations. In this study, surface Brillouin scattering (SBS) is utilized to determine the elastic constants, Poisson's ratio, and Young's modulus of these porous low-k SiOC:H films (˜ 25-250 nm thick) grown on Si substrates by probing surface acoustic phonons and their dispersions.

  17. Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

    KAUST Repository

    Onyegam, Emmanuel U.

    2014-04-14

    Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼ 25 μ m semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (Voc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in Voc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed. © 2014 AIP Publishing LLC.

  18. Planar ultra thin glass seals with optical fiber interface for monitoring tamper attacks on security eminent components

    Science.gov (United States)

    Thiel, M.; Flachenecker, G.; Schade, W.; Gorecki, C.; Thoma, A.; Rathje, R.

    2017-11-01

    Optical seals consisting of waveguide Bragg grating sensor structures in ultra thin glass transparencies have been developed to cover security relevant objects for detection of unauthorized access. For generation of optical signature in the seals, femtosecond laser pulses were used. The optical seals were connected with an optical fiber to enable external read out of the seal. Different attack scenarios for getting undetected access to the object, covered by the seal, were proven and evaluated. The results presented here, verify a very high level of security. An unauthorized detaching and subsequent replacement by original or copy of the seals for tampering would be accompanied with a very high technological effort, posing a substantial barrier towards an attacker. Additionally, environmental influences like temperature effects have a strong but reproducible influence on signature, which in context of a temperature reference database increases the level of security significantly.

  19. 3D lumped components and miniaturized bandpass filter in an ultra-thin M-LCP for SOP applications

    KAUST Repository

    Arabi, Eyad A.

    2013-01-01

    In this work, a library of 3D lumped components completely embedded in the thinnest, multilayer LCP (M-LCP) stack- up with four metallization layers and 100 μm of total thickness, is reported for the first time. A vertically and horizontally interdigitated capacitor, realized in this stack-up, provides higher self resonant frequency as compared to a similarly sized conventional parallel plate capacitor. Based on the above mentioned library, a miniaturized bandpass filter is presented for the GPS application. It utilizes mutually coupled inductors and is the smallest reported in the literature with a size of (0.035×0.028×0.00089)λg. Finally, the same filter realized in a competing ceramic technology (LTCC) is compared in performance with the ultra-thin M-LCP design. The M-LCP module presented in this work is inherently exible and offers great potential for wearable and conformal applications.

  20. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui

    2010-09-01

    The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.

  1. HIP (hot isostatic pressing) sintering of Tantalum (Ta) and tantalum carbide (TaC) powder mixture: relations between microstructure and properties

    International Nuclear Information System (INIS)

    Valin, F.; Schnedecker, M.

    1994-01-01

    HIP sintering at 1630 C and 195 MPa, during 2 hours, can be used for complete densification of mixtures of commercial tantalum carbide and tantalum powders. HIPed material properties are depending upon initial compositions. For C/Ta ratios inferior to 80%, the monocarbide structure is preserved. A partial ordering of the carbon vacancies will result, for TaC(0.80), in microhardness maximization. The microstructurally homogenous TaC(0.45) shows an excellent toughness. 2 figs., 2 refs

  2. III-V Ultra-Thin-Body InGaAs/InAs MOSFETs for Low Standby Power Logic Applications

    Science.gov (United States)

    Huang, Cheng-Ying

    As device scaling continues to sub-10-nm regime, III-V InGaAs/InAs metal- oxide-semiconductor ?eld-e?ect transistors (MOSFETs) are promising candidates for replacing Si-based MOSFETs for future very-large-scale integration (VLSI) logic applications. III-V InGaAs materials have low electron effective mass and high electron velocity, allowing higher on-state current at lower VDD and reducing the switching power consumption. However, III-V InGaAs materials have a narrower band gap and higher permittivity, leading to large band-to-band tunneling (BTBT) leakage or gate-induced drain leakage (GIDL) at the drain end of the channel, and large subthreshold leakage due to worse electrostatic integrity. To utilize III-V MOSFETs in future logic circuits, III-V MOSFETs must have high on-state performance over Si MOSFETs as well as very low leakage current and low standby power consumption. In this dissertation, we will report InGaAs/InAs ultra-thin-body MOSFETs. Three techniques for reducing the leakage currents in InGaAs/InAs MOSFETs are reported as described below. 1) Wide band-gap barriers: We developed AlAs0.44Sb0.56 barriers lattice-match to InP by molecular beam epitaxy (MBE), and studied the electron transport in In0.53Ga0.47As/AlAs 0.44Sb0.56 heterostructures. The InGaAs channel MOSFETs using AlAs0.44Sb0.56 bottom barriers or p-doped In0.52 Al0.48As barriers were demonstrated, showing significant suppression on the back barrier leakage. 2) Ultra-thin channels: We investigated the electron transport in InGaAs and InAs ultra-thin quantum wells and ultra-thin body MOSFETs (t ch ~ 2-4 nm). For high performance logic, InAs channels enable higher on-state current, while for low power logic, InGaAs channels allow lower BTBT leakage current. 3) Source/Drain engineering: We developed raised InGaAs and recessed InP source/drain spacers. The raised InGaAs source/drain spacers improve electrostatics, reducing subthreshold leakage, and smooth the electric field near drain, reducing

  3. Nanostructure control: Nucleation and diffusion studies for predictable ultra thin film morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Hershberger, Matthew [Iowa State Univ., Ames, IA (United States)

    2017-05-06

    This thesis covers PhD research on two systems with unique and interesting physics. The first system is lead (Pb) deposited on the silicon (111) surface with the 7x7 reconstruction. Pb and Si are mutually bulk insoluble resulting in this system being an ideal case for studying metal and semiconductor interactions. Initial Pb deposition causes an amorphous wetting layer to form across to surface. Continued deposition results in Pb(111) island growth. Classic literature has classified this system as the Stranski-Krastanov growth mode although the system is not near equilibrium conditions. Our research shows a growth mode distinctly different than classical expectations and begins a discussion of reclassifying diffusion and nucleation for systems far away from the well-studied equilibrium cases.

  4. Ultrafine TaC powders prepared in a high frequency plasma

    International Nuclear Information System (INIS)

    Canteloup, J.; Mocellin, A.

    1976-01-01

    Ultrafine tantalum carbide powders were prepared under conditions allowing higher purities to be achieved than when plasma or chemical vapour deposition techniques are used. The process consists of dissociation-vaporisation of powders in a radio frequency argon plasma followed by quenching of the vapours and collection in an electrostatic precipitator. Physical and chemical properties are given. The presence of excess carbon appears to protect against oxidation and as a dispersing medium for the carbide powders. (U.K.)

  5. Indigenous unit for bending and twisting tests of ultra-thin films on a flexible substrate

    Science.gov (United States)

    D'souza, Slavia Deeksha; Hazarika, Pratim; Prakasarao, Ch Surya; Kovendhan, M.; Kumar, R. Arockia; Joseph, D. Paul

    2018-04-01

    An indigenous unit is designed to test the stability of thin films deposited on to a flexible substrate by inducing a required number of bending and twisting under specific conditions. The unit is designed using aluminum and automated by sending pulse width modulated signals to servo motors using ATmega328 microcontroller. We have tested the unit by imparting stress on to a commercial ITO film deposited on a PET substrate. After a definite number of bending and twisting cycles, the electrical and surface properties are studied and the results are discussed.

  6. Diode behavior in ultra-thin low temperature ALD grown zinc-oxide on silicon

    Directory of Open Access Journals (Sweden)

    Nazek El-Atab

    2013-10-01

    Full Text Available A thin-film ZnO(n/Si(p+ heterojunction diode is demonstrated. The thin film ZnO layer is deposited by Atomic Layer Deposition (ALD at different temperatures on a p-type silicon substrate. Atomic force microscopy (AFM AC-in-Air method in addition to conductive AFM (CAFM were used for the characterization of ZnO layer and to measure the current-voltage characteristics. Forward and reverse bias n-p diode behavior with good rectification properties is achieved. The diode with ZnO grown at 80°C exhibited the highest on/off ratio with a turn-on voltage (VON ∼3.5 V. The measured breakdown voltage (VBR and electric field (EBR for this diode are 5.4 V and 3.86 MV/cm, respectively.

  7. Preparation and characterization of ultra-thin amphiphobic coatings on silicon wafers

    International Nuclear Information System (INIS)

    Mou, Chun-Yueh; Yuan, Wei-Li; Shih, Chih-Hsin

    2013-01-01

    Fluorine-based amphiphobic coatings have been widely used in commercial domestic utensils and textiles to repel water and oil contaminants. However, few reports from the literature survey have discussed the effects on amphiphobicity of the nano- to micro-scale surface features of such a coating. In this research thin amphiphobic epoxy coatings based on a mixture of bisphenol A diglycidyl ether, tetraethylorthosilicate (TEOS), and a particular alkoxy silane with fluorinated side chains (F-silane) are deposited on silicon wafers. Film amphiphobicity is characterized by the measurement of water and oil contact angles of the coating. Film morphology is revealed in the scanned images using atomic force microscopy. The deposited films free of F-silane are about 10 nm thick. When a small amount of F-silane was firstly added, the water and oil contact angles of the deposited films jumped up to 107° and 69° respectively and then flattened out with increased F-silane. Water droplets gave an average plateau contact angle about 110°, while vegetable oil ones, 40°. It was noted that there is a dramatic decrease in the lyophobicity causing a reduction in contact angles. However, surface lyophobicity also depends on sub-microscopic surface structures. In addition, by increasing TEOS, it was shown that the formed silica sols or granules were helpful in enhancing the mechanical strength along with retaining the lyophobicity of the film. - Highlights: • Epoxy ultrathin films about 10 nm thick deposited on silicon wafer. • Nominal fluorinated silane added to epoxy coatings for amphiphobicity. • Surface lyophobicity retained by sub-micrometer granules in ultrathin coatings. • Film hardness improved by adding tetraethylorthosilicate

  8. Preparation and characterization of ultra-thin amphiphobic coatings on silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chun-Yueh, E-mail: cymou165@gmail.com; Yuan, Wei-Li; Shih, Chih-Hsin

    2013-06-30

    Fluorine-based amphiphobic coatings have been widely used in commercial domestic utensils and textiles to repel water and oil contaminants. However, few reports from the literature survey have discussed the effects on amphiphobicity of the nano- to micro-scale surface features of such a coating. In this research thin amphiphobic epoxy coatings based on a mixture of bisphenol A diglycidyl ether, tetraethylorthosilicate (TEOS), and a particular alkoxy silane with fluorinated side chains (F-silane) are deposited on silicon wafers. Film amphiphobicity is characterized by the measurement of water and oil contact angles of the coating. Film morphology is revealed in the scanned images using atomic force microscopy. The deposited films free of F-silane are about 10 nm thick. When a small amount of F-silane was firstly added, the water and oil contact angles of the deposited films jumped up to 107° and 69° respectively and then flattened out with increased F-silane. Water droplets gave an average plateau contact angle about 110°, while vegetable oil ones, 40°. It was noted that there is a dramatic decrease in the lyophobicity causing a reduction in contact angles. However, surface lyophobicity also depends on sub-microscopic surface structures. In addition, by increasing TEOS, it was shown that the formed silica sols or granules were helpful in enhancing the mechanical strength along with retaining the lyophobicity of the film. - Highlights: • Epoxy ultrathin films about 10 nm thick deposited on silicon wafer. • Nominal fluorinated silane added to epoxy coatings for amphiphobicity. • Surface lyophobicity retained by sub-micrometer granules in ultrathin coatings. • Film hardness improved by adding tetraethylorthosilicate.

  9. Sintering study and properties of alumina matrix composites reinforced with NbC, TiC and TaC

    International Nuclear Information System (INIS)

    Tonello, K.P.S.; Trombini, V.; Bressiani, A.H.A.; Bressiani, J.C.

    2011-01-01

    Al_2O_3 based composite materials are very promising due to their good mechanical properties, and have been studied as an alternative for the production of materials with high wear resistance. In alumina based composites the addition of carbides can change and improve the sintering and mechanical properties of materials. The objective was to study the effect of adding small concentrations of NbC, TaC and TiC in the sintering, microstructure and mechanical properties of alumina composites. The sintering study was conducted in dilatometer, with heating rate of 20 ° C / min. up to 1800 ° C, and the study of microstructure and properties of the composites was performed in hot pressed samples, sintered at 1500°C/30min with constant pressure of 20MPa. The results indicated that the addition of carbides modified the sintering behavior and also indicated that the hardness and fracture toughness were improved by the presence of carbide particles. (author)

  10. The Effect of Nb on the Continuous Cooling Transformation Curves of Ultra-Thin Strip CASTRIP© Steels

    Directory of Open Access Journals (Sweden)

    Kristin R. Carpenter

    2015-10-01

    Full Text Available The effect of Nb on the hardenability of ultra-thin cast strip (UCS steels produced via the unique regime of rapid solidification, large austenite grain size, and inclusion engineering of the CASTRIP© process was investigated. Continuous cooling transformation (CCT diagrams were constructed for 0, 0.014, 0.024, 0.04, 0.06 and 0.08 wt% Nb containing UCS steels. Phase nomenclature for the identification of lower transformation product in low carbon steels was reviewed. Even a small addition of 0.014 wt% Nb showed a potent effect on hardenability, shifting the ferrite C-curve to the right and expanding the bainitic ferrite and acicular ferrite phase fields. Higher Nb additions increased hardenability further, suppressed the formation of ferrite to even lower cooling rates, progressively lowered the transformation start and finish temperatures and promoted the transformation of bainite instead of acicular ferrite. The latter was due to Nb suppressing the formation of allotriomorphic ferrite and allowing bainite to nucleate at prior austenite grain boundaries, a lower energy site than that for the intragranular nucleation of acicular ferrite at inclusions. Strength and hardness increased with increasing Nb additions, largely due to microstructural strengthening and solid solution hardening, but not from precipitation hardening.

  11. Uncorrelated multiple conductive filament nucleation and rupture in ultra-thin high-κ dielectric based resistive random access memory

    KAUST Repository

    Wu, Xing

    2011-08-29

    Resistive switching in transition metal oxides could form the basis for next-generation non-volatile memory (NVM). It has been reported that the current in the high-conductivity state of several technologically relevant oxide materials flows through localized filaments, but these filaments have been characterized only individually, limiting our understanding of the possibility of multiple conductive filaments nucleation and rupture and the correlation kinetics of their evolution. In this study, direct visualization of uncorrelated multiple conductive filaments in ultra-thin HfO2-based high-κ dielectricresistive random access memory (RRAM) device has been achieved by high-resolution transmission electron microscopy (HRTEM), along with electron energy loss spectroscopy(EELS), for nanoscale chemical analysis. The locations of these multiple filaments are found to be spatially uncorrelated. The evolution of these microstructural changes and chemical properties of these filaments will provide a fundamental understanding of the switching mechanism for RRAM in thin oxide films and pave way for the investigation into improving the stability and scalability of switching memory devices.

  12. General method for simultaneous optimization of light trapping and carrier collection in an ultra-thin film organic photovoltaic cell

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Cheng-Chia, E-mail: ct2443@columbia.edu; Grote, Richard R.; Beck, Jonathan H.; Kymissis, Ioannis [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States); Osgood, Richard M. [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States); Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Englund, Dirk [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-07-14

    We describe a general method for maximizing the short-circuit current in thin planar organic photovoltaic (OPV) heterojunction cells by simultaneous optimization of light absorption and carrier collection. Based on the experimentally obtained complex refractive indices of the OPV materials and the thickness-dependence of the internal quantum efficiency of the OPV active layer, we analyze the potential benefits of light trapping strategies for maximizing the overall power conversion efficiency of the cell. This approach provides a general strategy for optimizing the power conversion efficiency of a wide range of OPV structures. In particular, as an experimental trial system, the approach is applied here to a ultra-thin film solar cell with a SubPc/C{sub 60} photovoltaic structure. Using a patterned indium tin oxide (ITO) top contact, the numerically optimized designs achieve short-circuit currents of 0.790 and 0.980 mA/cm{sup 2} for 30 nm and 45 nm SubPc/C{sub 60} heterojunction layer thicknesses, respectively. These values correspond to a power conversion efficiency enhancement of 78% for the 30 nm thick cell, but only of 32% for a 45 nm thick cell, for which the overall photocurrent is actually higher. Applied to other material systems, the general optimization method can elucidate if light trapping strategies can improve a given cell architecture.

  13. Flexible Mixed-Potential-Type (MPT NO2 Sensor Based on An Ultra-Thin Ceramic Film

    Directory of Open Access Journals (Sweden)

    Rui You

    2017-07-01

    Full Text Available A novel flexible mixed-potential-type (MPT sensor was designed and fabricated for NO2 detection from 0 to 500 ppm at 200 °C. An ultra-thin Y2O3-doped ZrO2 (YSZ ceramic film 20 µm thick was sandwiched between a heating electrode and reference/sensing electrodes. The heating electrode was fabricated by a conventional lift-off process, while the porous reference and the sensing electrodes were fabricated by a two-step patterning method using shadow masks. The sensor’s sensitivity is achieved as 58.4 mV/decade at the working temperature of 200 °C, as well as a detection limit of 26.7 ppm and small response time of less than 10 s at 200 ppm. Additionally, the flexible MPT sensor demonstrates superior mechanical stability after bending over 50 times due to the mechanical stability of the YSZ ceramic film. This simply structured, but highly reliable flexible MPT NO2 sensor may lead to wide application in the automobile industry for vehicle emission systems to reduce NO2 emissions and improve fuel efficiency.

  14. Molecular dynamics simulations of disjoining pressure effects in ultra-thin water films on a metal surface

    Science.gov (United States)

    Hu, Han; Sun, Ying

    2013-11-01

    Disjoining pressure, the excess pressure in an ultra-thin liquid film as a result of van der Waals interactions, is important in lubrication, wetting, flow boiling, and thin film evaporation. The classic theory of disjoining pressure is developed for simple monoatomic liquids. However, real world applications often utilize water, a polar liquid, for which fundamental understanding of disjoining pressure is lacking. In the present study, molecular dynamics (MD) simulations are used to gain insights into the effect of disjoining pressure in a water thin film. Our MD models were firstly validated against Derjaguin's experiments on gold-gold interactions across a water film and then verified against disjoining pressure in an argon thin film using the Lennard-Jones potential. Next, a water thin film adsorbed on a gold surface was simulated to examine the change of vapor pressure with film thickness. The results agree well with the classic theory of disjoining pressure, which implies that the polar nature of water molecules does not play an important role. Finally, the effects of disjoining pressure on thin film evaporation in nanoporous membrane and on bubble nucleation are discussed.

  15. XPS and angle resolved XPS, in the semiconductor industry: Characterization and metrology control of ultra-thin films

    International Nuclear Information System (INIS)

    Brundle, C.R.; Conti, Giuseppina; Mack, Paul

    2010-01-01

    This review discusses the development of X-ray photoelectron spectroscopy, XPS, used as a characterization and metrology method for ultra-thin films in the semiconductor wafer processing industry. After a brief explanation of how the relative roles of XPS and Auger electron spectroscopy, AES, have changed over the last 15 years or so in the semiconductor industry, we go into some detail as to what is implied by metrology, as opposed to characterization, for thin films in the industry, and then describe how XPS, and particularly angle resolved XPS, ARXPS, have been implemented as a metrology 'tool' for thickness, chemical composition, and non-destructive depth profiling, of transistor gate oxide material, a key requirement in front-end processing. We take a historical approach, dealing first with the early use for SiO 2 films on Si(1 0 0), then moving to silicon oxynitride, SiO x N y in detail, and finally and briefly HfO 2 -based material, which is used today in the most advanced devices (32 nm node).

  16. Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Biao, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com; Xu, Jianquan; Sun, Shuzheng; Liu, Yue; Yang, Juping; Zhang, Li; Wang, Xinping, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com [Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2016-06-21

    Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.

  17. Ultra-thin and strong formvar-based membranes with controlled porosity for micro- and nano-scale systems

    Science.gov (United States)

    Auchter, Eric; Marquez, Justin; Stevens, Garrison; Silva, Rebecca; Mcculloch, Quinn; Guengerich, Quintessa; Blair, Andrew; Litchfield, Sebastian; Li, Nan; Sheehan, Chris; Chamberlin, Rebecca; Yarbro, Stephen L.; Dervishi, Enkeleda

    2018-05-01

    We present a methodology for developing ultra-thin and strong formvar-based membranes with controlled morphologies. Formvar is a thin hydrophilic and oleophilic polymer inert to most chemicals and resistant to radiation. The formvar-based membranes are viable materials as support structures in micro- and macro-scale systems depending on thinness and porosity control. Tunable sub-micron thick porous membranes with 20%–65% porosity were synthesized by controlling the ratios of formvar, glycerol, and chloroform. This synthesis process does not require complex separation or handling methods and allows for the production of strong, thin, and porous formvar-based membranes. An expansive array of these membrane characterizations including chemical compatibility, mechanical responses, wettability, as well as the mathematical simulations as a function of porosity has been presented. The wide range of chemical compatibility allows for membrane applications in various environments, where other polymers would not be suitable. Our formvar-based membranes were found to have an elastic modulus of 7.8 GPa, a surface free energy of 50 mN m‑1 and an average thickness of 125 nm. Stochastic model simulations indicate that formvar with the porosity of ∼50% is the optimal membrane formulation, allowing the most material transfer across the membrane while also withstanding the highest simulated pressure loadings before tearing. Development of novel, resilient and versatile membranes with controlled porosity offers a wide range of exciting applications in the fields of nanoscience, microfluidics, and MEMS.

  18. Structural characterization and comparison of iridium, platinum and gold/palladium ultra-thin film coatings for STM of biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Sebring, R.; Arendt, P.; Imai, B.; Bradbury, E.M.; Gatewood, J. [Los Alamos National Lab., NM (United States); Panitz, J. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Physics and Astronomy; Yau, P. [Univ. of California, Davis, CA (United States)

    1997-10-30

    Scanning tunneling microscopy (STM) is capable of atomic resolution and is ideally suited for imaging surfaces with uniform work function. A biological sample on a conducting substrate in air does not meet this criteria and requires a conductive coating for stable and reproducible STM imaging. In this paper, the authors describe the STM and transmission electron microscopy (TEM) characterization of ultra-thin ion-beam sputtered films of iridium and cathode sputtered gold/palladium and platinum films on highly ordered pyrolytic graphite (HOPG) which were developed for use as biomolecule coatings. The goals were the development of metal coatings sufficiently thin and fine grained that 15--20 {angstrom} features of biological molecules could be resolved using STM, and the development of a substrate/coating system which would allow complementary TEM information to be obtained for films and biological molecules. The authors demonstrate in this paper that ion-beam sputtered iridium on highly ordered pyrolytic graphite (HOPG) has met both these goals. The ion-beam sputtered iridium produced a very fine grained (< 10 {angstrom}) continuous film at 5--6 {angstrom} thickness suitable for stable air STM imaging. In comparison, cathode sputtered platinum produced 16 {angstrom} grains with the thinnest continuous film at 15 {angstrom} thickness, and the sputtered gold/palladium produced 25 {angstrom} grains with the thinnest continuous film at 18 {angstrom} thickness.

  19. Fabrication of Through via Holes in Ultra-Thin Fused Silica Wafers for Microwave and Millimeter-Wave Applications

    Directory of Open Access Journals (Sweden)

    Xiao Li

    2018-03-01

    Full Text Available Through via holes in fused silica are a key infrastructure element of microwave and millimeter-wave circuits and 3D integration. In this work, etching through via holes in ultra-thin fused silica wafers using deep reactive-ion etching (DRIE and laser ablation was developed and analyzed. The experimental setup and process parameters for both methods are presented and compared. For DRIE, three types of mask materials including KMPR 1035 (Nippon Kayaku, Tokyo, Japan photoresist, amorphous silicon and chromium—with their corresponding optimized processing recipes—were tested, aiming at etching through a 100 μm fused silica wafer. From the experiments, we concluded that using chromium as the masking material is the best choice when using DRIE. However, we found that the laser ablation method with a laser pulse fluence of 2.89 J/cm2 and a pulse overlap of 91% has advantages over DRIE. The laser ablation method has a simpler process complexity, while offering a fair etching result. In particular, the sidewall profile angle is measured to be 75° to the bottom surface of the wafer, which is ideal for the subsequent metallization process. As a demonstration, a two-inch wafer with 624 via holes was processed using both technologies, and the laser ablation method showed better efficiency compared to DRIE.

  20. The design of an ultra-thin and multiple channels optical receiving antenna system with freeform lenses

    Science.gov (United States)

    Zhang, Lingyun; Cheng, Dewen; Hu, Yuan; Song, Weitao; Wang, Yongtian

    2014-11-01

    Visible Light Communications (VLC) has become an emerging area of research since it can provide higher data transmission speed and wider bandwidth. The white LEDs are very important components of the VLC system, because it has the advantages of higher brightness, lower power consumption, and a longer lifetime. More importantly, their intensity and color are modulatable. Besides the light source, the optical antenna system also plays a very important role in the VLC system since it determines the optical gain, effective working area and transmission rate of the VLC system. In this paper, we propose to design an ultra-thin and multiple channels optical antenna system by tiling multiple off-axis lenses, each of which consists of two reflective and two refractive freeform surfaces. The tiling of multiple systems and detectors but with different band filters makes it possible to design a wavelength division multiplexing VLC system to highly improve the system capacity. The field of view of the designed antenna system is 30°, the entrance pupil diameter is 1.5mm, and the thickness of the system is under 4mm. The design methods are presented and the results are discussed in the last section of this paper. Besides the optical gain is analyzed and calculated. The antenna system can be tiled up to four channels but without the increase of thickness.

  1. Design and analyses of an ultra-thin flat lens for wave front shaping in the visible

    International Nuclear Information System (INIS)

    Huang, Kai; Li, Yiyan; Tian, Xuelong; Zeng, Dajun; Gao, Xueli

    2015-01-01

    An ultra-thin flat lens is proposed for focusing circularly polarized light in the visible range. Anisotropic C-shaped nanoantennas with phase discontinuities are used to form the metasurface of the lens. The phase response of the C-shaped nanoantennas can be manipulated by simply rotating the angle of the unit nanoantenna. A 600 nm incident circularly polarized light is focused by the proposed techniques. Good agreements are observed by using our MoM and a commercial FDTD software package. The computation time spent by using MoM is approximately 10–100 times smaller than using FDTD. All the results show the proposed nanoantenna array has a great potential for nanoscale optical microscopy, solar cell energy conversion enhancement, as well as integrated optical circuits. - Highlights: • Successfully focusing a 600 nm light using a circularly C-shaped nanoantenna array. • The computation time spent by using MoM is approximately 10–100 times smaller than FDTD. • A good agreement is observed using our MoM to the classic FDTD method.

  2. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    Science.gov (United States)

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-11-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

  3. Simplified tunnelling current calculation for MOS structures with ultra-thin oxides for conductive atomic force microscopy investigations

    International Nuclear Information System (INIS)

    Frammelsberger, Werner; Benstetter, Guenther; Stamp, Richard; Kiely, Janice; Schweinboeck, Thomas

    2005-01-01

    As charge tunnelling through thin and ultra-thin silicon dioxide layers is regarded as the driving force for MOS device degradation the determination and characterisation of electrically week spots is of paramount importance for device reliability and failure analysis. Conductive atomic force microscopy (C-AFM) is able to address this issue with a spatial resolution smaller than the expected breakdown spot. For the determination of the electrically active oxide thickness in practice an easy to use model with sufficient accuracy and which is largely independent of the oxide thickness is required. In this work a simplified method is presented that meets these demands. The electrically active oxide thickness is determined by matching of C-AFM voltage-current curves and a tunnelling current model, which is based on an analytical tunnelling current approximation. The model holds for both the Fowler-Nordheim tunnelling and the direct tunnelling regime with one single tunnelling parameter set. The results show good agreement with macroscopic measurements for gate voltages larger than approximately 0.5-1 V, and with microscopic C-AFM measurements. For this reason arbitrary oxides in the DT and the FNT regime may be analysed with high lateral resolution by C-AFM, without the need of a preselection of the tunnelling regime to be addressed

  4. Nanostructure Control: Nucleation and Diffusion Studies for Predictable Ultra Thin Film Morphologies

    Science.gov (United States)

    Hershberger, Matthew Thomas

    This thesis covers PhD research on two systems with unique and interesting physics. The first system is lead (Pb) deposited on the silicon (111) surface with the 7x7 reconstruction. Pb and Si are mutually bulk insolubility resulting in this system being an ideal case for studying metal and semiconductor interactions. Initial Pb deposition causes an amorphous wetting layer to form across to surface. Continued deposition results in Pb(111) island growth. Classic literature has classified this system as the Stranski-Krastanov growth mode although the system is not near equilibrium conditions. Our research shows a growth mode distinctly different than classical expectations and begins a discussion of reclassifying diffusion and nucleation for systems far away from the well-studied equilibrium cases. The second system studied investigates the interactions of the Rare Earth metal Dysprosium (Dy) with a carbon based 2D lattice called graphene. Graphene is a 2D material composed of carbon atoms arranged in hexagons, similar to a honeycomb with carbon atoms at each corner. The graphene we used is grown epitaxially from a substrate of silicon carbide. This creates a multilayered playground to study how metals interact both on the surface of graphene and intercalated in between graphene layers. Many types of atoms have been studied in graphene systems, but the rare earths and in particular Dy have not been well investigated. This thesis contributes to the knowledge base of graphene on SiC structure and metal-graphene interactions. These systems have been investigated in ultra-high vacuum (UHV) environments with base pressures around 5.0x10-11 torr. The Pb/Si(111)-7x7 system was investigated with scanning tunneling microscopy (STM) and the Graphene/SiC system was investigated with both STM and Spot Profile Analyzing Low Energy Electron Diffraction (SPA-LEED).

  5. Morphology and N₂ Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes.

    Science.gov (United States)

    Fernandez, Ekain; Sanchez-Garcia, Jose Angel; Viviente, Jose Luis; van Sint Annaland, Martin; Gallucci, Fausto; Tanaka, David A Pacheco

    2016-02-10

    The influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM), and the results indicate an increase of the grain size from 120 to 250-270 nm and film surface roughness from 4-5 to 10-12 nm when increasing the temperature from around 360-510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5-2-µm thick) films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO₂ 3-nm top layer supports (smallest pore size among all tested) present high N₂ permeance in the order of 10(-6) mol·m(-2)·s(-1)·Pa(-1) at room temperature.

  6. Morphology and N2 Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes

    Directory of Open Access Journals (Sweden)

    Ekain Fernandez

    2016-02-01

    Full Text Available The influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM, and the results indicate an increase of the grain size from 120 to 250–270 nm and film surface roughness from 4–5 to 10–12 nm when increasing the temperature from around 360–510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5–2-µm thick films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO2 3-nm top layer supports (smallest pore size among all tested present high N2 permeance in the order of 10−6 mol·m−2·s−1·Pa−1 at room temperature.

  7. Test beam analysis of ultra-thin hybrid pixel detector assemblies with Timepix readout ASICs

    CERN Document Server

    Alipour Tehrani, Niloufar; Dannheim, Dominik; Firu, Elena; Kulis, Szymon; Redford, Sophie; Sicking, Eva

    2016-01-01

    The requirements for the vertex detector at the proposed Compact Linear Collider imply a very small material budget: less than 0.2% of a radiation length per detection layer including services and mechanical supports. We present here a study using Timepix readout ASICs hybridised to pixel sensors of 50 − 500 μm thickness, including assemblies with 100 μm thick sensors bonded to thinned 100μm thick ASICs. Sensors from three producers (Advacam, Micron Semiconductor Ltd, Canberra) with different edge termination technologies (active edge, slim edge) were bonded to Timepix ASICs. These devices were characterised with the EUDET telescope at the DESY II test beam using 5.6 GeV electrons. Their performance for the detection and tracking of minimum ionising particles was evaluated in terms of charge sharing, detection efficiency, single-point resolution and energy deposition.

  8. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets.

    Science.gov (United States)

    Gabriel, Tobias; Rommel, Daniel; Scherm, Florian; Gorywoda, Marek; Glatzel, Uwe

    2017-03-10

    Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co-28Cr-9W-1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE) study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM) and scanning electron microscopy (SEM), combined with electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDX). Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  9. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets

    Directory of Open Access Journals (Sweden)

    Tobias Gabriel

    2017-03-01

    Full Text Available Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co–28Cr–9W–1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM and scanning electron microscopy (SEM, combined with electron backscatter diffraction (EBSD and energy dispersive X-ray spectroscopy (EDX. Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  10. Ferroelectric transistors with monolayer molybdenum disulfide and ultra-thin aluminum-doped hafnium oxide

    Science.gov (United States)

    Yap, Wui Chung; Jiang, Hao; Liu, Jialun; Xia, Qiangfei; Zhu, Wenjuan

    2017-07-01

    In this letter, we demonstrate ferroelectric memory devices with monolayer molybdenum disulfide (MoS2) as the channel material and aluminum (Al)-doped hafnium oxide (HfO2) as the ferroelectric gate dielectric. Metal-ferroelectric-metal capacitors with 16 nm thick Al-doped HfO2 are fabricated, and a remnant polarization of 3 μC/cm2 under a program/erase voltage of 5 V is observed. The capability of potential 10 years data retention was estimated using extrapolation of the experimental data. Ferroelectric transistors based on embedded ferroelectric HfO2 and MoS2 grown by chemical vapor deposition are fabricated. Clockwise hysteresis is observed at low program/erase voltages due to slow bulk traps located near the 2D/dielectric interface, while counterclockwise hysteresis is observed at high program/erase voltages due to ferroelectric polarization. In addition, the endurances of the devices are tested, and the effects associated with ferroelectric materials, such as the wake-up effect and polarization fatigue, are observed. Reliable writing/reading in MoS2/Al-doped HfO2 ferroelectric transistors over 2 × 104 cycles is achieved. This research can potentially lead to advances of two-dimensional (2D) materials in low-power logic and memory applications.

  11. Characterization of nano-powder grown ultra-thin film p-CuO/n-Si hetero-junctions by employing vapour-liquid-solid method for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Sultana, Jenifar; Das, Anindita [Centre for Research in Nanoscience and Nanotechnology (CRNN), Kolkata 700098 (India); Das, Avishek [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India); Saha, Nayan Ranjan [Department of Polymer Science and Technology, University of Calcutta, Kolkata 700009 (India); Karmakar, Anupam [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India); Chattopadhyay, Sanatan, E-mail: scelc@caluniv.ac.in [Department of Electronic Science, University of Calcutta, Kolkata 700009 (India)

    2016-08-01

    In this work, the CuO nano-powder has been synthesized by employing chemical bath deposition technique for its subsequent use to grow ultrathin film (20 nm) of p-CuO on n-Si substrate for the fabrication of p-CuO/n-Si hetero-junction diodes. The thin CuO film has been grown by employing vapour-liquid-solid method. The crystalline structure and chemical phase of the film are characterized by employing field-emission scanning electron microscopy and X-ray diffraction studies. Chemical stoichiometry of the film has been confirmed by using energy dispersive X-ray spectroscopy. The potential for photovoltaic applications of such films is investigated by measuring the junction current-voltage characteristics and by extracting the relevant parameters such as open circuit photo-generated voltage, short circuit current density, fill-factor and energy conversion efficiency. - Highlights: • Synthesis of CuO nano-powder by CBD method • Growth of ultra-thin film of CuO by employing VLS method for the first time • Physical and electrical characterization of such films for photovoltaic applications • Estimation of energy conversion efficiency of the p-CuO/n-Si p-n junction solar cell.

  12. Multispectral surface plasmon resonance approach for ultra-thin silver layer characterization: Application to top-emitting OLED cathode

    Science.gov (United States)

    Taverne, S.; Caron, B.; Gétin, S.; Lartigue, O.; Lopez, C.; Meunier-Della-Gatta, S.; Gorge, V.; Reymermier, M.; Racine, B.; Maindron, T.; Quesnel, E.

    2018-01-01

    While dielectric/metal/dielectric (DMD) multilayer thin films have raised considerable interest as transparent and conductive electrodes in various optoelectronic devices, the knowledge of optical characteristics of thin metallic layers integrated in such structures is still rather approximate. The multispectral surface plasmon resonance characterization approach described in this work precisely aims at providing a rigorous methodology able to accurately determine the optical constants of ultra-thin metallic films. As a practical example, the refractive index and extinction dispersion curves of 8 to 25 nm-thick silver layers have been investigated. As a result, their extreme dependence on the layer thickness is highlighted, in particular in a thickness range close to the critical threshold value (˜10 nm) where the silver film becomes continuous and its electrical conductance/optical transmittance ratio particularly interesting. To check the validity of the revisited Ag layers constant dispersion curves deduced from this study, they were introduced into a commercial optical model software to simulate the behavior of various optoelectronic building blocks from the simplest ones (DMD electrodes) to much more complex structures [full organic light emitting device (OLED) stacks]. As a result, a much better prediction of the emission spectrum profile as well as the angular emission pattern of top-emitting OLEDs is obtained. On this basis, it is also shown how a redesign of the top encapsulation thin film of OLEDs is necessary to better take benefit from the advanced DMD electrode. These results should particularly interest the micro-OLED display field where bright and directive single color pixel emission is required.

  13. Design of a CMOS readout circuit on ultra-thin flexible silicon chip for printed strain gauges

    Directory of Open Access Journals (Sweden)

    M. Elsobky

    2017-09-01

    Full Text Available Flexible electronics represents an emerging technology with features enabling several new applications such as wearable electronics and bendable displays. Precise and high-performance sensors readout chips are crucial for high quality flexible electronic products. In this work, the design of a CMOS readout circuit for an array of printed strain gauges is presented. The ultra-thin readout chip and the printed sensors are combined on a thin Benzocyclobutene/Polyimide (BCB/PI substrate to form a Hybrid System-in-Foil (HySiF, which is used as an electronic skin for robotic applications. Each strain gauge utilizes a Wheatstone bridge circuit, where four Aerosol Jet® printed meander-shaped resistors form a full-bridge topology. The readout chip amplifies the output voltage difference (about 5 mV full-scale swing of the strain gauge. One challenge during the sensor interface circuit design is to compensate for the relatively large dc offset (about 30 mV at 1 mA in the bridge output voltage so that the amplified signal span matches the input range of an analog-to-digital converter (ADC. The circuit design uses the 0. 5 µm mixed-signal GATEFORESTTM technology. In order to achieve the mechanical flexibility, the chip fabrication is based on either back thinned wafers or the ChipFilmTM technology, which enables the manufacturing of silicon chips with a thickness of about 20 µm. The implemented readout chip uses a supply of 5 V and includes a 5-bit digital-to-analog converter (DAC, a differential difference amplifier (DDA, and a 10-bit successive approximation register (SAR ADC. The circuit is simulated across process, supply and temperature corners and the simulation results indicate excellent performance in terms of circuit stability and linearity.

  14. Solid-State Densification of Spun-Cast Self-Assembled Monolayers for Use in Ultra-Thin Hybrid Dielectrics.

    Science.gov (United States)

    Hutchins, Daniel O; Acton, Orb; Weidner, Tobias; Cernetic, Nathan; Baio, Joe E; Castner, David G; Ma, Hong; Jen, Alex K-Y

    2012-11-15

    Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlO x (2.5 nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7×10 -8 A cm -2 and capacitance density of 0.62 µF cm -2 at 3 V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2 V operation and charge carrier mobilites of up to 1.1 cm 2 V -1 s -1 .

  15. Misfit strain-film thickness phase diagrams and related electromechanical properties of epitaxial ultra-thin lead zirconate titanate films

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Q.Y.; Mahjoub, R. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Alpay, S.P. [Materials Science and Engineering Program and Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Nagarajan, V., E-mail: nagarajan@unsw.edu.au [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2010-02-15

    The phase stability of ultra-thin (0 0 1) oriented ferroelectric PbZr{sub 1-x}Ti{sub x}O{sub 3} (PZT) epitaxial thin films as a function of the film composition, film thickness, and the misfit strain is analyzed using a non-linear Landau-Ginzburg-Devonshire thermodynamic model taking into account the electrical and mechanical boundary conditions. The theoretical formalism incorporates the role of the depolarization field as well as the possibility of the relaxation of in-plane strains via the formation of microstructural features such as misfit dislocations at the growth temperature and ferroelastic polydomain patterns below the paraelectric-ferroelectric phase transformation temperature. Film thickness-misfit strain phase diagrams are developed for PZT films with four different compositions (x = 1, 0.9, 0.8 and 0.7) as a function of the film thickness. The results show that the so-called rotational r-phase appears in a very narrow range of misfit strain and thickness of the film. Furthermore, the in-plane and out-of-plane dielectric permittivities {epsilon}{sub 11} and {epsilon}{sub 33}, as well as the out-of-plane piezoelectric coefficients d{sub 33} for the PZT thin films, are computed as a function of misfit strain, taking into account substrate-induced clamping. The model reveals that previously predicted ultrahigh piezoelectric coefficients due to misfit-strain-induced phase transitions are practically achievable only in an extremely narrow range of film thickness, composition and misfit strain parameter space. We also show that the dielectric and piezoelectric properties of epitaxial ferroelectric films can be tailored through strain engineering and microstructural optimization.

  16. Ultra-thin silicon (UTSi) on insulator CMOS transceiver and time-division multiplexed switch chips for smart pixel integration

    Science.gov (United States)

    Zhang, Liping; Sawchuk, Alexander A.

    2001-12-01

    We describe the design, fabrication and functionality of two different 0.5 micron CMOS optoelectronic integrated circuit (OEIC) chips based on the Peregrine Semiconductor Ultra-Thin Silicon on insulator technology. The Peregrine UTSi silicon- on-sapphire (SOS) technology is a member of the silicon-on- insulator (SOI) family. The low-loss synthetic sapphire substrate is optically transparent and has good thermal conductivity and coefficient of thermal expansion properties, which meet the requirements for flip-chip bonding of VCSELs and other optoelectronic input-output components. One chip contains transceiver and network components, including four channel high-speed CMOS transceiver modules, pseudo-random bit stream (PRBS) generators, a voltage controlled oscillator (VCO) and other test circuits. The transceiver chips can operate in both self-testing mode and networking mode. An on- chip clock and true-single-phase-clock (TSPC) D-flip-flop have been designed to generate a PRBS at over 2.5 Gb/s for the high-speed transceiver arrays to operate in self-testing mode. In the networking mode, an even number of transceiver chips forms a ring network through free-space or fiber ribbon interconnections. The second chip contains four channel optical time-division multiplex (TDM) switches, optical transceiver arrays, an active pixel detector and additional test devices. The eventual applications of these chips will require monolithic OEICs with integrated optical input and output. After fabrication and testing, the CMOS transceiver array dies will be packaged with 850 nm vertical cavity surface emitting lasers (VCSELs), and metal-semiconductor- metal (MSM) or GaAs p-i-n detector die arrays to achieve high- speed optical interconnections. The hybrid technique could be either wire bonding or flip-chip bonding of the CMOS SOS smart-pixel arrays with arrays of VCSELs and photodetectors onto an optoelectronic chip carrier as a multi-chip module (MCM).

  17. Hadron-therapy beam monitoring: Towards a new generation of ultra-thin p-type silicon strip detectors

    International Nuclear Information System (INIS)

    Bouterfa, M.; Aouadi, K.; Bertrand, D.; Olbrechts, B.; Delamare, R.; Raskin, J. P.; Gil, E. C.; Flandre, D.

    2011-01-01

    Hadron-therapy has gained increasing interest for cancer treatment especially within the last decade. System commissioning and quality assurance procedures impose to monitor the particle beam using 2D dose measurements. Nowadays, several monitoring systems exist for hadron-therapy but all show a relatively high influence on the beam properties: indeed, most devices consist of several layers of materials that degrade the beam through scattering and energy losses. For precise treatment purposes, ultra-thin silicon strip detectors are investigated in order to reduce this beam scattering. We assess the beam size increase provoked by the Multiple Coulomb Scattering when passing through Si, to derive a target thickness. Monte-Carlo based simulations show a characteristic scattering opening angle lower than 1 mrad for thicknesses below 20 μm. We then evaluated the fabrication process feasibility. We successfully thinned down silicon wafers to thicknesses lower than 10 μm over areas of several cm 2 . Strip detectors are presently being processed and they will tentatively be thinned down to 20 μm. Moreover, two-dimensional TCAD simulations were carried out to investigate the beam detector performances on p-type Si substrates. Additionally, thick and thin substrates have been compared thanks to electrical simulations. Reducing the pitch between the strips increases breakdown voltage, whereas leakage current is quite insensitive to strips geometrical configuration. The samples are to be characterized as soon as possible in one of the IBA hadron-therapy facilities. For hadron-therapy, this would represent a considerable step forward in terms of treatment precision. (authors)

  18. Effect of nanoparticles as lubricant additives on friction and wear behavior of tetrahedral amorphous carbon (ta-C coating

    Directory of Open Access Journals (Sweden)

    Xiang Li

    2018-03-01

    Full Text Available As diamond like carbon (DLC coating becomes increasingly popular in providing low friction and wear under lubricated conditions, the effect of various oil additives on tribological behavior of DLC coating is drawing more attention. Various oil additives, such as ZnDTP and MoDTC, have been widely used in automobile engine industry to pursuit excellent tribological performance in the insufficient lubrication condition. Although such commercial oil additives have been proven to reduce friction or/and wear to some extent, usage of such high -SAPS (sulphuric ash, phosphor, sulfphur conventional additives is bound to arouse concerns due to environmental reasons. In this research, we investigate the effect of two nanoparticle oil additives, which are cerium oxide (CeO2 and zirconium dioxide (ZrO2, on friction and wear of non-hydrogen tetrahedral amorphous carbon (ta-C coating. The results show that by adding ZrO2 nanoparticle, the friction of DLC coating could be reduced about 32% compared to non-additive base oil scenario, but specific wear rate increases by 40%. When CeO2 nanoparticle is used, friction increases by 22% compared to non-additive base oil scenario, however wear decreases by nearly 77%.

  19. CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

    KAUST Repository

    Ghoneim, Mohamed T.; Hanna, Amir; Hussain, Muhammad Mustafa

    2014-01-01

    Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.

  20. Charge selective contact on ultra-thin In(OH)xS y/Pb(OH) xS y heterostructure prepared by SILAR

    International Nuclear Information System (INIS)

    Gavrilov, S.; Oja, I.; Lim, B.; Belaidi, A.; Bohne, W.; Strub, E.; Roehrich, J.; Lux-Steiner, M.-Ch.; Dittrich, Th.

    2006-01-01

    Ultra-thin In(OH) x S y /Pb(OH) x S y heterostructures were formed by the wet chemical SILAR (successive ion layer adsorption and reaction) technique. ERDA (elastic recoil detection analysis) was used for stoichiometry analysis. The heterocontacts were conditioned by joint annealing of the two layers at different low temperatures in air. The charge selectivity was demonstrated with various small area solar cell structures. The results are discussed on the base of formation of bonds between sulphide clusters and passivation of defects with hydrogen containing species in hydroxy-sulphides. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

    KAUST Repository

    Ghoneim, Mohamed T.

    2014-08-01

    Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.

  2. Solid-state densification of spun-cast self-assembled monolayers for use in ultra-thin hybrid dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Hutchins, Daniel O.; Acton, Orb [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Weidner, Tobias [Department of Bioengineering, University of Washington, Seattle, WA 98195 (United States); Cernetic, Nathan [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Baio, Joe E. [Department of Chemical Engineering, University of Washington, Seattle, WA 98195 (United States); Castner, David G. [Department of Bioengineering, University of Washington, Seattle, WA 98195 (United States); Department of Chemical Engineering, University of Washington, Seattle, WA 98195 (United States); Ma, Hong, E-mail: hma@uw.edu [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Jen, Alex K.-Y., E-mail: ajen@uw.edu [Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States); Department of Chemistry, University of Washington, Seattle, WA 98195 (United States)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Rapid processing of SAM in ambient conditions is achieved by spin coating. Black-Right-Pointing-Pointer Thermal annealing of a bulk spun-cast molecular film is explored as a mechanism for SAM densification. Black-Right-Pointing-Pointer High-performance SAM-oxide hybrid dielectric is obtained utilizing a single wet processing step. - Abstract: Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlO{sub x} (2.5 nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7 Multiplication-Sign 10{sup -8} A cm{sup -2} and capacitance density of 0.62 {mu}F cm{sup -2} at 3 V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2 V operation and charge carrier mobilites of up to

  3. Influence of Surface Passivation on AlN Barrier Stress and Scattering Mechanism in Ultra-thin AlN/GaN Heterostructure Field-Effect Transistors.

    Science.gov (United States)

    Lv, Y J; Song, X B; Wang, Y G; Fang, Y L; Feng, Z H

    2016-12-01

    Ultra-thin AlN/GaN heterostructure field-effect transistors (HFETs) with, and without, SiN passivation were fabricated by the same growth and device processes. Based on the measured DC characteristics, including the capacitance-voltage (C-V) and output current-voltage (I-V) curves, the variation of electron mobility with gate bias was found to be quite different for devices with, and without, SiN passivation. Although the AlN barrier layer is ultra thin (c. 3 nm), it was proved that SiN passivation induces no additional tensile stress and has no significant influence on the piezoelectric polarization of the AlN layer using Hall and Raman measurements. The SiN passivation was found to affect the surface properties, thereby increasing the electron density of the two-dimensional electron gas (2DEG) under the access region. The higher electron density in the access region after SiN passivation enhanced the electrostatic screening for the non-uniform distributed polarization charges, meaning that the polarization Coulomb field scattering has a weaker effect on the electron drift mobility in AlN/GaN-based devices.

  4. Tuning of Rashba/Dresselhaus Spin Splittings by Inserting Ultra-Thin InAs Layers at Interfaces in Insulating GaAs/AlGaAs Quantum Wells.

    Science.gov (United States)

    Yu, Jinling; Zeng, Xiaolin; Cheng, Shuying; Chen, Yonghai; Liu, Yu; Lai, Yunfeng; Zheng, Qiao; Ren, Jun

    2016-12-01

    The ratio of Rashba and Dresselhaus spin splittings of the (001)-grown GaAs/AlGaAs quantum wells (QWs), investigated by the spin photocurrent spectra induced by circular photogalvanic effect (CPGE) at inter-band excitation, has been effectively tuned by changing the well width of QWs and by inserting a one-monolayer-thick InAs layer at interfaces of GaAs/AlGaAs QWs. Reflectance difference spectroscopy (RDS) is also employed to study the interface asymmetry of the QWs, whose results are in good agreement with that obtained by CPGE measurements. It is demonstrated that the inserted ultra-thin InAs layers will not only introduce structure inversion asymmetry (SIA), but also result in additional interface inversion asymmetry (IIA), whose effect is much stronger in QWs with smaller well width. It is also found that the inserted InAs layer brings in larger SIA than IIA. The origins of the additional SIA and IIA introduced by the inserted ultra-thin InAs layer have been discussed.

  5. Using an ultra-thin non-doped orange emission layer to realize high efficiency white organic light-emitting diodes with low efficiency roll-off

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liping; Chen, Jiangshan; Ma, Dongge, E-mail: mdg1014@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate University of the Chinese Academy of Sciences, Changchun 130022 (China); Zhao, Yongbiao [Luminous Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Zhang, Hongmei [Department of Materials Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China)

    2014-06-28

    By adopting an ultra-thin non-doped orange emission layer sandwiched between two blue emission layers, high efficiency white organic light-emitting diodes (WOLEDs) with reduced efficiency roll-off were fabricated. The optimized devices show a balanced white emission with Internationale de L'Eclairage of (0.41, 0.44) at the luminance of 1000 cd/m{sup 2}, and the maximum power efficiency, current efficiency (CE), and external quantum efficiency reach 63.2 lm/W, 59.3 cd/A, and 23.1%, which slightly shift to 53.4 lm/W, 57.1 cd/A, and 22.2% at 1000 cd/m{sup 2}, respectively, showing low efficiency roll-off. Detailed investigations on the recombination zone and the transient electroluminescence (EL) clearly reveal the EL processes of the ultra-thin non-doped orange emission layer in WOLEDs.

  6. The high-flux effect on deuterium retention in TiC and TaC doped tungsten at high temperatures

    Science.gov (United States)

    Zibrov, Mikhail; Bystrov, Kirill; Mayer, Matej; Morgan, Thomas W.; Kurishita, Hiroaki

    2017-10-01

    Samples made of tungsten (W) doped either with titanium carbide (W-1.1TiC) or tantalum carbide (W-3.3TaC) were exposed to a low-energy (40 eV/D), high-flux (1.8-5 × 1023 D/m2s) deuterium (D) plasma at temperatures of about800 K, 1050 K, and 1250 K to a fluence of about1 × 1027 D/m2. The deuterium (D) inventory in the samples was examined by nuclear reaction analysis and thermal desorption spectroscopy. At 800 K the D bulk concentrations and total D inventories in W-1.1TiC and W-3.3TaC were more than one order of magnitude higher compared to that in pure polycrystalline W. At 1050 K and 1250 K the D concentrations in all types of samples were very low (≤10-5 at. fr.); however the D inventories in W-1.1TiC were significantly higher compared to those in W-3.3TaC and pure W. It is suggested that D trapping inside the carbide precipitates and at their boundaries is essential at high temperatures and high incident fluxes, especially in W-1.1TiC.

  7. Experimental study of ultra-thin films mechanical integrity by combined nanoindentation and nano-acoustic emission

    Science.gov (United States)

    Zhang, Zihou

    Advancement of interconnect technology has imposed significant challenge on interface characterization and reliability for blurred interfaces between layers. There is a need for material properties and these miniaturized length scales and assessment of reliability; including the intrinsic film fracture toughness and the interfacial fracture toughness. The nano-meter range of film thicknesses currently employed, impose significant challenges on evaluating these physical quantities and thereby impose significant challenge on the design cycle. In this study we attempted to use a combined nano-indentation and nano-acoustic emission to qualitatively and quantitatively characterize the failure modes in ultra-thin blanket films on Si substrates or stakes of different characteristics. We have performed and analyzed an exhaustive group of testes that cove many diverge combination of film-substrate combination, provided by both Intel and IBM. When the force-indentation depth curve shows excursion, a direct measure of the total energy release rate is estimated. The collected acoustic emission signal is then used to partition the total energy into two segments, one associated with the cohesive fracture toughness of the film and the other is for the adhesive fracture toughness of the interface. The acoustic emission signal is analyzed in both the time and frequency domain to achieve such energy division. In particular, the signal time domain analysis for signal skewness, time of arrival and total energy content are employed with the proper signal to noise ratio. In the frequency domain, an expansive group of acoustic emission signals are utilized to construct the details of the power spectral density. A bank of band-pass filters are designed to sort the individual signals to those associated with adhesive interlayer cracking, cohesive channel cracking, or other system induced noise. The attenuation time and the energy content within each spectral frequency were the key elements

  8. 4P-NPD ultra thin-films as efficient exciton blocking layers in DBP/C70 based organic solar cells

    DEFF Research Database (Denmark)

    Patil, Bhushan Ramesh; Liu, Yiming; Qamar, Talha

    2017-01-01

    Exciton blocking effects from ultra thin layers of N,N'-di-1-naphthalenyl-N,N'-diphenyl [1,1':4',1'':4'',1'''-quaterphenyl]-4,4'''-diamine (4P-NPD) was investigated in small molecule based inverted Organic Solar Cells (OSCs) using Tetraphenyldibenzoperiflanthene (DBP) as the electron donor material...... and fullerene (C70) as the electron acceptor material. The short-circuit current density (Jsc) and PCE of the optimized OSCs with 0.7 nm thick 4P-NPD were approx. 16 % and 24 % higher, respectively, compared to reference devices without exciton blocking layers. Drift diffusion based device modeling...... was conducted to model the full Current density – Voltage (JV) characteristics and EQE spectrum of the OSCs, and photoluminescence measurements was conducted to investigate the exciton blocking effects with increasing thicknesses of the 4P-NPD layer. Importantly, coupled optical and electrical modeling studies...

  9. Experimental validation of an ultra-thin metasurface cloak for hiding a metallic obstacle from an antenna radiation at low frequencies

    Science.gov (United States)

    Teperik, Tatiana V.; Burokur, Shah Nawaz; de Lustrac, André; Sabanowski, Guy; Piau, Gérard-Pascal

    2017-07-01

    We demonstrate numerically and experimentally an ultra-thin (≈ λ/240) metasurface-based invisibility cloak for low frequency antenna applications. We consider a monopole antenna mounted on a ground plane and a cylindrical metallic obstacle of diameter smaller than the wavelength located in its near-field. To restore the intrinsic radiation patterns of the antenna perturbed by this obstacle, a metasurface cloak consisting simply of a metallic patch printed on a dielectric substrate is wrapped around the obstacle. Using a finite element method based commercial electromagnetic solver, we show that the radiation patterns of the monopole antenna can be restored completely owing to electromagnetic modes of the resonant cavity formed between the patch and obstacle. The metasurface cloak is fabricated, and the concept is experimentally demonstrated at 125 MHz. Performed measurements are in good agreement with numerical simulations, verifying the efficiency of the proposed cloak.

  10. Heteroepitaxial growth and surface structure of L1{sub 0}-MnGa(111) ultra-thin films on GaN(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Mandru, Andrada-Oana; Wang, Kangkang; Cooper, Kevin; Ingram, David C.; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Garcia Diaz, Reyes; Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Haider, Muhammad [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261 (Saudi Arabia)

    2013-10-14

    L1{sub 0}-structured MnGa(111) ultra-thin films were heteroepitaxially grown on GaN(0001) under lightly Mn-rich conditions using molecular beam epitaxy. Room-temperature scanning tunneling microscopy (STM) investigations reveal smooth terraces and angular step edges, with the surface structure consisting primarily of a 2 × 2 reconstruction along with small patches of 1 × 2. Theoretical calculations were carried out using density functional theory, and the simulated STM images were calculated using the Tersoff-Hamman approximation, revealing that a stoichiometric 1 × 2 and a Mn-rich 2 × 2 surface structure give the best agreement with the observed experimental images.

  11. ANALYSIS ON THE BEHAVIOR OF PRECIPITATES IN ULTRA-THIN HOT STRIP OF PLAIN LOW CARBON STEEL PRODUCED BY COMPACT STRIP PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    H. Yu; Y.L. Kang; H.B. Dong; D.L. Liu; J. Fu

    2002-01-01

    This paper investigated the mechanism of precipitation and its influence upon prop-erties of ultra-thin hot strips of low carbon steel produced by CSP techniques usingexperiment and thermodynamics theory. The experimental results show that thereare lots of fine and dispersive precipitates in microstructures. By analysis, most ofaluminum nitrides are in grains, while coexisted precipitates of MnS are along grainboundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3in the core, while MnS is at the fringe of surface. The precipitation behavior of AlNand MnS in the hot strip is studied by thermodynamic calculation. At last, implica-tions between strengthening effect and techniques are analyzed using obtained solubilityproducts.

  12. CO2 laser cutting of ultra thin (75 μm) glass based rigid optical solar reflector (OSR) for spacecraft application

    Science.gov (United States)

    Mishra, Shubham; Sridhara, N.; Mitra, Avijit; Yougandar, B.; Dash, Sarat Kumar; Agarwal, Sanjay; Dey, Arjun

    2017-03-01

    Present study reports for the first time laser cutting of multilayered coatings on both side of ultra thin (i.e., 75 μm) glass substrate based rigid optical solar reflector (OSR) for spacecraft thermal control application. The optimization of cutting parameters was carried out as a function of laser power, cutting speed and number of cutting passes and their effect on cutting edge quality. Systematic and in-detail microstructural characterizations were carried out by optical and scanning electron microscopy techniques to study the laser affected zone and cutting edge quality. Sheet resistance and water contact angle experiments were also conducted locally both prior and after laser cut to investigate the changes of electrical and surface properties, if any.

  13. A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers.

    Science.gov (United States)

    Xu, Man; Wachters, Arthur J H; van Deelen, Joop; Mourad, Maurice C D; Buskens, Pascal J P

    2014-03-10

    We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIGS layer does not decrease monotonically with its layer thickness due to interference effects. Ergo, high precision is required in the CIGS production process, especially when using ultra-thin absorber layers, to accurately realize the required thickness of the ZnO, cadmium sulfide (CdS) and CIGS layer. We show that patterning the ZnO window layer can strongly suppress these interference effects allowing a higher tolerance in the production process.

  14. Resistive switching of organic–inorganic hybrid devices of conductive polymer and permeable ultra-thin SiO2 films

    Science.gov (United States)

    Yamamoto, Shunsuke; Kitanaka, Takahisa; Miyashita, Tokuji; Mitsuishi, Masaya

    2018-06-01

    We propose a resistive switching device composed of conductive polymer (PEDOT:PSS) and SiO2 ultra-thin films. The SiO2 film was fabricated from silsesquioxane polymer nanosheets as a resistive switching layer. Devices with metal (Ag or Au)∣SiO2∣PEDOT:PSS architecture show good resistive switching performance with set–reset voltages as low as several hundred millivolts. The device properties and the working mechanism were investigated by varying the electrode material, surrounding atmosphere, and SiO2 film thickness. Results show that resistive switching is based on water and ion migration at the PEDOT:PSS∣SiO2 interface.

  15. Optical investigation of atomic steps in ultra-thin InGaAs/InP quantum wells grown by vapor levitation epitaxy

    International Nuclear Information System (INIS)

    Morais, P.C.

    1988-09-01

    Ultra-thin InGaAs/InP single-quantum-well structures, grown by chloride transport vapor levitation epitaxy, have been investigated by low temperature photoluminescence (PL). Well resolved peaks are observed in the PL spectra which we attribute to monolayer (a/2=2.93 A) variations in quantum well (QW) thickness. Separate peak positions for QW thicknesses corresponding to 2-6 monolayers have been determined, providing an unambiguous thickness calibration for spectral shifts due to quantum confinement. The PL peak corresponding to two monolayers occurs at 1.314 eV corresponding to an energy shift of 524 meV. Experimental data agree very well with a simple effective-mass theory. (author) [pt

  16. Advanced technique for ultra-thin residue inspection with sub-10nm thickness using high-energy back-scattered electrons

    Science.gov (United States)

    Han, Jin-Hee

    2018-03-01

    Recently the aspect ratio of capacitor and via hole of memory semiconductor device has been dramatically increasing in order to store more information in a limited area. A small amount of remained residues after etch process on the bottom of the high aspect ratio structure can make a critical failure in device operation. Back-scattered electrons (BSE) are mainly used for inspecting the defect located at the bottom of the high aspect ratio structure or analyzing the overlay of the multi-layer structure because these electrons have a high linearity with the direction of emission and a high kinetic energy above 50eV. However, there is a limitation on that it cannot detect ultra-thin residue material having a thickness of several nanometers because the surface sensitivity is extremely low. We studied the characteristics of BSE spectra using Monte Carlo simulations for several cases which the high aspect ratio structures have extreme microscopic residues. Based on the assumption that most of the electrons emitted without energy loss are localized on the surface, we selected the detection energy window which has a range of 20eV below the maximum energy of the BSE. This window section is named as the high-energy BSE region. As a result of comparing the detection sensitivity of the conventional and the high-energy BSE detection mode, we found that the detection sensitivity for the residuals which have 2nm thickness is improved by more than 10 times in the high-energy BSE mode. This BSE technology is a new inspection method that can greatly be improved the inspection sensitivity for the ultra-thin residual material presented in the high aspect ratio structure, and its application will be expanded.

  17. Influence of CdCl{sub 2} activation treatment on ultra-thin Cd{sub 1−x}Zn{sub x}S/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, A.J., E-mail: a.clayton@glyndwr.ac.uk [Centre for Solar Energy Research, Glyndŵr University, OpTIC, St. Asaph LL17 0JD (United Kingdom); Baker, M.A.; Babar, S. [Faculty of Engineering & Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Gibson, P.N. [Institute for Health & Consumer Protection, Joint Research Centre, 21020 Ispra, VA (Italy); Irvine, S.J.C.; Kartopu, G.; Lamb, D.A.; Barrioz, V. [Centre for Solar Energy Research, Glyndŵr University, OpTIC, St. Asaph LL17 0JD (United Kingdom)

    2015-09-01

    Ultra-thin CdTe photovoltaic solar cells with an absorber thickness of 0.5 μm were produced by metal organic chemical vapour deposition onto indium tin oxide coated boroaluminosilicate glass. A wide band gap Cd{sub 1−x}Zn{sub x}S alloy window layer was employed to improve spectral response in the blue region of the solar spectrum. X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy were used to monitor changes in the chemical composition and microstructure of the Cd{sub 1−x}Zn{sub x}S/CdTe solar cell after varying the post-deposition CdCl{sub 2} activation treatment time and annealing temperature. The CdCl{sub 2} treatment leached Zn from the Cd{sub 1−x}Zn{sub x}S layer causing a redshift in the spectral response onset of window absorption. S diffusion occurred across the Cd{sub 1−x}Zn{sub x}S/CdTe interface, which was more pronounced as the CdCl{sub 2} treatment was increased. A CdTe{sub 1−y}S{sub y} alloy was formed at the interface, which thickened with CdCl{sub 2} treatment time. Small concentrations of S (up to 2 at.%) were observed throughout the CdTe layer as the degree of CdCl{sub 2} treatment was increased. Greater S diffusion across the Cd{sub 1−x}Zn{sub x}S/CdTe interface caused the device open-circuit voltage (V{sub oc}) to increase. The higher V{sub oc} is attributed to enhanced strain relaxation and associated reduction of defects in the interface region as well as the increase in CdTe grain size. - Highlights: • Increased CdCl{sub 2} activation treatment resulted in loss of Zn from Cd{sub 1−x}Zn{sub x}S. • Sulphur diffusion into CdTe was enhanced with greater CdCl{sub 2} activation treatment. • Improvement to V{sub oc} correlated with increased sulphur diffusion into CdTe.

  18. Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

    Science.gov (United States)

    Geenen, F. A.; van Stiphout, K.; Nanakoudis, A.; Bals, S.; Vantomme, A.; Jordan-Sweet, J.; Lavoie, C.; Detavernier, C.

    2018-02-01

    The electrical contact of the source and drain regions in state-of-the-art CMOS transistors is nowadays facilitated through NiSi, which is often alloyed with Pt in order to avoid morphological agglomeration of the silicide film. However, the solid-state reaction between as-deposited Ni and the Si substrate exhibits a peculiar change for as-deposited Ni films thinner than a critical thickness of tc = 5 nm. Whereas thicker films form polycrystalline NiSi upon annealing above 450 ° C , thinner films form epitaxial NiSi2 films that exhibit a high resistance toward agglomeration. For industrial applications, it is therefore of utmost importance to assess the critical thickness with high certainty and find novel methodologies to either increase or decrease its value, depending on the aimed silicide formation. This paper investigates Ni films between 0 and 15 nm initial thickness by use of "thickness gradients," which provide semi-continuous information on silicide formation and stability as a function of as-deposited layer thickness. The alloying of these Ni layers with 10% Al, Co, Ge, Pd, or Pt renders a significant change in the phase sequence as a function of thickness and dependent on the alloying element. The addition of these ternary impurities therefore changes the critical thickness tc. The results are discussed in the framework of classical nucleation theory.

  19. The influence of alloying on the phase formation sequence of ultra-thin nickel silicide films and on the inheritance of texture

    Science.gov (United States)

    Geenen, F. A.; Solano, E.; Jordan-Sweet, J.; Lavoie, C.; Mocuta, C.; Detavernier, C.

    2018-05-01

    The controlled formation of silicide materials is an ongoing challenge to facilitate the electrical contact of Si-based transistors. Due to the ongoing miniaturisation of the transistor, the silicide is trending to ever-thinner thickness's. The corresponding increase in surface-to-volume ratio emphasises the importance of low-energetic interfaces. Intriguingly, the thickness reduction of nickel silicides results in an abrupt change in phase sequence. This paper investigates the sequence of the silicides phases and their preferential orientation with respect to the Si(001) substrate, for both "thin" (i.e., 9 nm) and "ultra-thin" (i.e., 3 nm) Ni films. Furthermore, as the addition of ternary elements is often considered in order to tailor the silicides' properties, additives of Al, Co, and Pt are also included in this study. Our results show that the first silicide formed is epitaxial θ-Ni2Si, regardless of initial thickness or alloyed composition. The transformations towards subsequent silicides are changed through the additive elements, which can be understood through solubility arguments and classical nucleation theory. The crystalline alignment of the formed silicides with the substrate significantly differs through alloying. The observed textures of sequential silicides could be linked through texture inheritance. Our study illustrates the nucleation of a new phase drive to reduce the interfacial energy at the silicide-substrate interface as well as at the interface with the silicide which is being consumed for these sub-10 nm thin films.

  20. 4P-NPD ultra-thin films as efficient exciton blocking layers in DBP/C70 based organic solar cells

    Science.gov (United States)

    Patil, Bhushan R.; Liu, Yiming; Qamar, Talha; Rubahn, Horst-Günter; Madsen, Morten

    2017-09-01

    Exciton blocking effects from ultra-thin layers of N,N‧-di-1-naphthalenyl-N,N‧-diphenyl [1,1‧:4‧,1″:4″,1‴-quaterphenyl]-4,4‴-diamine (4P-NPD) were investigated in small molecule-based inverted organic solar cells (OSCs) using tetraphenyldibenzoperiflanthene as the electron donor material and fullerene (C70) as the electron acceptor material. The short-circuit current density (J SC) and power conversion efficiency (PCE) of the optimized OSCs with 0.7 nm thick 4P-NPD were approximately 16% and 24% higher, respectively, compared to reference devices without exciton blocking layers (EBLs). Drift diffusion-based device modeling was conducted to model the full current density-voltage (JV) characteristics and external quantum efficiency spectrum of the OSCs, and photoluminescence measurements were conducted to investigate the exciton blocking effects with increasing thicknesses of the 4P-NPD layer. Importantly, coupled optical and electrical modeling studies of the device behaviors and exciton generation rates and densities in the active layer for different 4P-NPD layer thicknesses were conducted, in order to gain a complete understanding of the observed increase in PCE for 4P-NPD layer thicknesses up to 1 nm, and the observed decrease in PCE for layer thicknesses beyond 1 nm. This work demonstrates a route for guiding the integration of EBLs in OSC devices.

  1. Microstructure and texture evolution of ultra-thin grain-oriented silicon steel sheet fabricated using strip casting and three-stage cold rolling method

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hong-Yu; Liu, Hai-Tao, E-mail: liuht@ral.neu.edu.cn; Wang, Yin-Ping; Wang, Guo-Dong

    2017-03-15

    A 0.1 mm-thick grain-oriented silicon steel sheet was successfully produced using strip casting and three-stage cold rolling method. The microstructure, texture and inhibitor evolution during the processing was briefly analyzed. It was found that Goss texture was absent in the hot rolled sheet because of the lack of shear deformation. After normalizing, a large number of dispersed MnS precipitates with the size range of 15–90 nm were produced. During first cold rolling, dense shear bands were generated in the deformed ferrite grains, resulting in the intense Goss texture after first intermediate annealing. The microstructure was further refined and homogenized during the subsequent cold rolling and annealing processes. After primary recrystallization annealing, a homogeneous microstructure consisting of fine and equiaxed grains was produced while the associated texture was characterized by a strong γ-fiber texture. Finally, a complete secondary recrystallization microstructure consisting of entirely large Goss grains was produced. The magnetic induction B{sub 8} and iron loss P{sub 10/400} was 1.79 T and 6.9 W/kg, respectively. - Highlights: • Ultra-thin grain-oriented silicon steel was produced by strip casting process. • Microstructure, texture and inhibitor evolution was briefly investigated. • Goss texture was absent in primary recrystallization annealed sheet. • MnS precipitates with a size range of 15–90 nm formed after normalizing. • A complete secondary recrystallization microstructure was produced.

  2. Nitrogen-doped biomass-based ultra-thin carbon nanosheets with interconnected framework for High-Performance Lithium-Ion Batteries

    Science.gov (United States)

    Guo, Shasha; Chen, Yaxin; Shi, Liluo; Dong, Yue; Ma, Jing; Chen, Xiaohong; Song, Huaihe

    2018-04-01

    In this paper, a low-cost and environmental friendly synthesis strategy is proposed to fabricate nitrogen-doped biomass-based ultra-thin carbon nanosheets (N-CNS) with interconnected framework by using soybean milk as the carbon precursor and sodium chloride as the template. The interconnected porous nanosheet structure is beneficial for lithium ion transportation, and the defects introduced by pyridine nitrogen doping are favorable for lithium storage. When used as the anodes for lithium-ion batteries, the N-CNS electrode shows a high initial reversible specific capacity of 1334 mAh g-1 at 50 mA g-1, excellent rate performance (1212, 555 and 336 mAh g-1 at 0.05, 0.5 and 2 A g-1, respectively) and good cycling stability (355 mAh g-1 at 1 A g-1 after 1000 cycles). Furthermore, this study demonstrates the prospects of biomass and soybean milk, as the potential anode for the application of electrochemical energy storage devices.

  3. Quantitative measurement of mean inner potential and specimen thickness from high-resolution off-axis electron holograms of ultra-thin layered WSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Florian, E-mail: f.winkler@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Tavabi, Amir H. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Gemeinschaftslabor für Elektronenmikroskopie (GFE), RWTH Aachen University, D-52074 Aachen (Germany); Duchamp, Martial [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Yucelen, Emrah [FEI Company, Achtseweg Noord 5, Eindhoven 5600 KA (Netherlands); Borghardt, Sven; Kardynal, Beata E. [Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, D-52425 Jülich (Germany); and others

    2017-07-15

    The phase and amplitude of the electron wavefunction that has passed through ultra-thin flakes of WSe{sub 2} is measured from high-resolution off-axis electron holograms. Both the experimental measurements and corresponding computer simulations are used to show that, as a result of dynamical diffraction, the spatially averaged phase does not increase linearly with specimen thickness close to an [001] zone axis orientation even when the specimen has a thickness of only a few layers. It is then not possible to infer the local specimen thickness of the WSe{sub 2} from either the phase or the amplitude alone. Instead, we show that the combined analysis of phase and amplitude from experimental measurements and simulations allows an accurate determination of the local specimen thickness. The relationship between phase and projected potential is shown to be approximately linear for extremely thin specimens that are tilted by several degrees in certain directions from the [001] zone axis. A knowledge of the specimen thickness then allows the electrostatic potential to be determined from the measured phase. By using this combined approach, we determine a value for the mean inner potential of WSe{sub 2} of 18.9±0.8 V, which is 12% lower than the value calculated from neutral atom scattering factors. - Highlights: • Quantitative analysis of high resolution electron holograms of WSe{sub 2}. • Local specimen thickness determination and estimation of tilt angle. • Mean inner potential evaluation of WSe2 avoiding dynamical diffraction.

  4. Preparation of c-axis perpendicularly oriented ultra-thin L10-FePt films on MgO and VN underlayers

    Science.gov (United States)

    Futamoto, Masaaki; Shimizu, Tomoki; Ohtake, Mitsuru

    2018-05-01

    Ultra-thin L10-FePt films of 2 nm average thickness are prepared on (001) oriented MgO and VN underlayers epitaxially grown on base substrate of SrTiO3(001) single crystal. Detailed cross-sectional structures are observed by high-resolution transmission electron microscopy. Continuous L10-FePt(001) thin films with very flat surface are prepared on VN(001) underlayer whereas the films prepared on MgO(001) underlayer consist of isolated L10-FePt(001) crystal islands. Presence of misfit dislocation and lattice bending in L10-FePt material is reducing the effective lattice mismatch with respect to the underlayer to be less than 0.5 %. Formation of very flat and continuous FePt layer on VN underlayer is due to the large surface energy of VN material where de-wetting of FePt material at high temperature annealing process is suppressed under a force balance between the surface and interface energies of FePt and VN materials. An employment of underlayer or substrate material with the lattice constant and the surface energy larger than those of L10-FePt is important for the preparation of very thin FePt epitaxial thin continuous film with the c-axis controlled to be perpendicular to the substrate surface.

  5. Rapid Biochemical Mixture Screening by Three-Dimensional Patterned Multifunctional Substrate with Ultra-Thin Layer Chromatography (UTLC) and Surface Enhanced Raman Scattering (SERS).

    Science.gov (United States)

    Lee, Bi-Shen; Lin, Pi-Chen; Lin, Ding-Zheng; Yen, Ta-Jen

    2018-01-11

    We present a three-dimensional patterned (3DP) multifunctional substrate with the functions of ultra-thin layer chromatography (UTLC) and surface enhanced Raman scattering (SERS), which simultaneously enables mixture separation, target localization and label-free detection. This multifunctional substrate is comprised of a 3DP silicon nanowires array (3DP-SiNWA), decorated with silver nano-dendrites (AgNDs) atop. The 3DP-SiNWA is fabricated by a facile photolithographic process and low-cost metal assisted chemical etching (MaCE) process. Then, the AgNDs are decorated onto 3DP-SiNWA by a wet chemical reduction process, obtaining 3DP-AgNDs@SiNWA multifunctional substrates. With various patterns designed on the substrates, the signal intensity could be maximized by the excellent confinement and concentrated effects of patterns. By using this 3DP-AgNDs@SiNWA substrate to scrutinize the mixture of two visible dyes, the individual target could be recognized and further boosted the Raman signal of target 15.42 times comparing to the un-patterned AgNDs@SiNWA substrate. Therefore, such a three-dimensional patterned multifunctional substrate empowers rapid mixture screening, and can be readily employed in practical applications for biochemical assays, food safety and other fields.

  6. Quantitative measurement of mean inner potential and specimen thickness from high-resolution off-axis electron holograms of ultra-thin layered WSe2.

    Science.gov (United States)

    Winkler, Florian; Tavabi, Amir H; Barthel, Juri; Duchamp, Martial; Yucelen, Emrah; Borghardt, Sven; Kardynal, Beata E; Dunin-Borkowski, Rafal E

    2017-07-01

    The phase and amplitude of the electron wavefunction that has passed through ultra-thin flakes of WSe 2 is measured from high-resolution off-axis electron holograms. Both the experimental measurements and corresponding computer simulations are used to show that, as a result of dynamical diffraction, the spatially averaged phase does not increase linearly with specimen thickness close to an [001] zone axis orientation even when the specimen has a thickness of only a few layers. It is then not possible to infer the local specimen thickness of the WSe 2 from either the phase or the amplitude alone. Instead, we show that the combined analysis of phase and amplitude from experimental measurements and simulations allows an accurate determination of the local specimen thickness. The relationship between phase and projected potential is shown to be approximately linear for extremely thin specimens that are tilted by several degrees in certain directions from the [001] zone axis. A knowledge of the specimen thickness then allows the electrostatic potential to be determined from the measured phase. By using this combined approach, we determine a value for the mean inner potential of WSe 2 of 18.9±0.8V, which is 12% lower than the value calculated from neutral atom scattering factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  7. Innovative Method for Automatic Shape Generation and 3D Printing of Reduced-Scale Models of Ultra-Thin Concrete Shells

    Directory of Open Access Journals (Sweden)

    Ana Tomé

    2018-02-01

    Full Text Available A research and development project has been conducted aiming to design and produce ultra-thin concrete shells. In this paper, the first part of the project is described, consisting of an innovative method for shape generation and the consequent production of reduced-scale models of the selected geometries. First, the shape generation is explained, consisting of a geometrically nonlinear analysis based on the Finite Element Method (FEM to define the antifunicular of the shell’s deadweight. Next, the scale model production is described, consisting of 3D printing, specifically developed to evaluate the aesthetics and visual impact, as well as to study the aerodynamic behaviour of the concrete shells in a wind tunnel. The goals and constraints of the method are identified and a step-by-step guidelines presented, aiming to be used as a reference in future studies. The printed geometry is validated by high-resolution assessment achieved by photogrammetry. The results are compared with the geometry computed through geometric nonlinear finite-element-based analysis, and no significant differences are recorded. The method is revealed to be an important tool for automatic shape generation and building scale models of shells. The latter enables the performing of wind tunnel tests to obtain pressure coefficients, essential for structural analysis of this type of structures.

  8. Ultra-Thin Multi-Band Polarization-Insensitive Microwave Metamaterial Absorber Based on Multiple-Order Responses Using a Single Resonator Structure

    Directory of Open Access Journals (Sweden)

    Yong Zhi Cheng

    2017-10-01

    Full Text Available We design an ultra-thin multi-band polarization-insensitive metamaterial absorber (MMA using a single circular sector resonator (CSR structure in the microwave region. Simulated results show that the proposed MMA has three distinctive absorption peaks at 3.35 GHz, 8.65 GHz, and 12.44 GHz, with absorbance of 98.8%, 99.7%, and 98.3%, respectively, which agree well with an experiment. Simulated surface current distributions of the unit-cell structure reveal that the triple-band absorption mainly originates from multiple-harmonic magnetic resonance. The proposed triple-band MMA can remain at a high absorption level for all polarization of both transverse-electric (TE and transverse-magnetic (TM modes under normal incidence. Moreover, by further optimizing the geometric parameters of the CSRs, four-band and five-band MMAs can also be obtained. Thus, our design will have potential application in detection, sensing, and stealth technology.

  9. Improvement of transistor characteristics and stability for solution-processed ultra-thin high-valence niobium doped zinc-tin oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Jeng, Jiann-Shing, E-mail: jsjeng@mail.nutn.edu.tw

    2016-08-15

    Nb-doped Zinc tin oxide (NZTO) channel materials have been prepared by solution process in combination with the spin-coating method. All NZTO thin film transistors (TFTs) are n-type enhancement-mode devices, either without or with Nb additives. High-valence niobium ion (ionic charge = +5) has a larger ionic potential and similar ionic radius to Zn{sup 2+} and Sn{sup 4+} ions. As compared with the pure ZTO device, introducing Nb{sup 5+} ions into the ZTO channel layers can improve the electrical properties and bias stability of TFTs because of the reduction of the oxygen vacancies. This study discusses the connection among the material properties of the NZTO films and the electrical performance and bias stability of NZTO TFTs and how they are influenced by the Nb/(Nb + Sn) molar ratios of NZTO films. - Highlights: • Ultra-thin high-valence niobium doped zinc-tin oxide (NZTO) thin films are prepared using a solution process. • Nb dopants in ZTO films reduce the oxygen vacancy and subgap adsorption of the ZTO films. • The Nb-doping concentration of the NZTO channel layer has a strong influence on the TFT performance.

  10. Impact of built-in fields and contact configuration on the characteristics of ultra-thin GaAs solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aeberhard, Urs, E-mail: u.aeberhard@fz-juelich.de [IEK-5 Photovoltaik, Forschungszentrum Jülich, D-52425 Jülich (Germany)

    2016-07-18

    We discuss the effects of built-in fields and contact configuration on the photovoltaic characteristics of ultra-thin GaAs solar cells. The investigation is based on advanced quantum-kinetic simulations reaching beyond the standard semi-classical bulk picture concerning the consideration of charge carrier states and dynamics in complex potential profiles. The thickness dependence of dark and photocurrent in the ultra-scaled regime is related to the corresponding variation of both, the built-in electric fields and associated modification of the density of states, and the optical intensity in the films. Losses in open-circuit voltage and short-circuit current due to the leakage of electronically and optically injected carriers at minority carrier contacts are investigated for different contact configurations including electron and hole blocking barrier layers. The microscopic picture of leakage currents is connected to the effect of finite surface recombination velocities in the semi-classical description, and the impact of these non-classical contact regions on carrier generation and extraction is analyzed.

  11. Study on characteristics of a double-conductible channel organic thin-film transistor with an ultra-thin hole-blocking layer

    International Nuclear Information System (INIS)

    Guang-Cai, Yuan; Zheng, Xu; Su-Ling, Zhao; Fu-Jun, Zhang; Xue-Yan, Tian; Xu-Rong, Xu; Na, Xu

    2009-01-01

    The properties of top-contact organic thin-film transistors (TC-OTFTs) using ultra-thin 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (BCP) as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers are limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at V DS = −20 V showed excellent hole mobility μFE and threshold voltage V TH of 0.58 cm 2 /(V·s) and −4.6 V, respectively

  12. Fabricating high-energy quantum dots in ultra-thin LiFePO4 nanosheets using a multifunctional high-energy biomolecule-ATP

    DEFF Research Database (Denmark)

    Zhang, X.D.; Bi, Z.Y.; He, W.

    2014-01-01

    By using a multifunctional high-energy biomolecule—adenosine triphosphate (ATP)—we fabricated highenergy quantum dots (HEQDs) with a feature size of less than 10 nm and used them in high-power lithium-ion batteries. We introduced high-energy phosphate bonds into the crystal structure of LiFePO4...... nanoparticles and synthesized the mesoporous biocarbon nanowire coated LiFePO4 with HEQDs (MBCNW-LFP-HEQDs) by using ATP as a phosphorus source, a nucleating agent, a structural template and a biocarbon source. HEGDs were homogeneously formed inside the ultra-thin LiFePO4 nanosheet and the mesoporous biocarbon...... nanowire network structure was coated on the surface of the nanosheet. In LiFePO4 nanoparticles, HEQDs result in more storage sites of Li+ ions and easier transfer kinetics of electrons and lithium ions, where the kinetic transformation path between LiFePO4 and FePO4 is rather different from the path...

  13. Impact of ultra-thin Al2O3-y layers on TiO2-x ReRAM switching characteristics

    Science.gov (United States)

    Trapatseli, Maria; Cortese, Simone; Serb, Alexander; Khiat, Ali; Prodromakis, Themistoklis

    2017-05-01

    Transition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electroforming (EF) switching voltages and low yields. Approaches such as engineering of the active layer by doping or addition of thin oxide buffer layers have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3-y buffer layers incorporated between TiO2-x thin films taking into account both 3+/4+ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3-y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a filamentary switching mechanism and provide enhanced filament stability, as shown by the cycling endurance measurements.

  14. Effects of Na incorporation and plasma treatment on Bi{sub 2}S{sub 3} ultra-thin layers

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Garcia, H., E-mail: hamog@ier.unam.mx [Laboratorio de Espectroscopía, Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62210 Cuernavaca, Morelos (Mexico); Messina, S. [Universidad Autónoma de Nayarit, Ciudad de la Cultura “Amado Nervo” S/N, C.P. 63155 Tepic, Nayarit (Mexico); Calixto-Rodriguez, M. [Universidad Tecnológica Emiliano Zapata del Estado de Morelos, Av. Universidad Tecnológica No. 1, C.P. 62760 Emiliano Zapata, Morelos (Mexico); Martínez, H. [Laboratorio de Espectroscopía, Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62210 Cuernavaca, Morelos (Mexico)

    2016-04-01

    As-deposited bismuth sulfide thin films prepared by means of a chemical bath deposition were treated with argon AC plasma. In this paper, we present the results on the physical modifications which were observed when a pre-treatment, containing a solution of 1 M sodium hydroxide, was applied to the glass substrates before depositing the bismuth sulfide. The bismuth sulfide thin films were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, UV–VIS, and electrical measurements. The XRD analysis demonstrated an enhancement in the crystalline properties, as well as an increment in the crystal size. The energy band gap value was calculated as 1.60 eV. Changes in photoconductivity (σ{sub p}) values were also observed due to the pre-treatment in NaOH. A value of σ{sub p} = 6.2 × 10{sup −6} (Ω cm){sup −1} was found for samples grown on substrates without pre-treatment, and a value of σ{sub p} = 0.28 (Ω cm){sup −1} for samples grown on substrates with pre-treatment. Such σ{sub p} values are optimal for the improvement of solar cells based on Bi{sub 2}S{sub 3} thin films as absorber material. - Highlights: • We report our findings about Na incorporation and plasma treatment on Bi{sub 2}S{sub 3} thin layers. • The Na pre-treatment improves the structural and electrical properties of Bi{sub 2}S{sub 3} films. • The E{sub g} value was 1.60 eV for films with pre-treatment with NaOH and treatment in Ar plasma.

  15. Micro-nanocomposites Al2O3/ NbC/ WC and Al2O3/ NbC/ TaC

    International Nuclear Information System (INIS)

    Santos, Thais da Silva

    2014-01-01

    Alumina based ceramics belong to a class of materials designated as structural, which are widely used in cutting tools. Although alumina has good properties for application as a structural ceramics, composites with different additives have been produced with the aim of improving its fracture toughness and mechanical strength. New studies point out micro-nanocomposites, wherein the addition of micrometric particles should enhance mechanical strength, and nano-sized particles enhance fracture toughness. In this work, alumina based micro nanocomposites were obtained by including nano-sized NbC and micrometer WC particles at 2:1, 6:4, 10:5 and 15:10 vol% proportions, and also with the inclusion of nano-sized NbC and micrometer TaC particles at 2:1 vol% proportion. For the study of densification, micro-nanocomposites were sintered in a dilatometer with a heating rate of 20°C/min until a temperature of 1800°C in argon atmosphere. Based on the dilatometry results, specimens were sintered in a resistive graphite furnace under argon atmosphere between 1500°C and 1700°C by holding the sintering temperature for 30 minutes. Densities, crystalline phases, hardness and tenacity were determined, and micro-nanocomposites microstructures were analyzed. The samples Al 2 O 3 : NbC: TaC sintered at 1700 ° C achieved the greater apparent density (~ 95% TD) and the sample sintered at 1600 ° C showed homogeneous microstructure and increased hardness value (15.8 GPa) compared to the pure alumina . The compositions with 3% inclusions are the most promising for future applications. (author)

  16. Formation of Surface and Quantum-Well States in Ultra Thin Pt Films on the Au(111 Surface

    Directory of Open Access Journals (Sweden)

    Igor V. Silkin

    2017-12-01

    Full Text Available The electronic structure of the Pt/Au(111 heterostructures with a number of Pt monolayers n ranging from one to three is studied in the density-functional-theory framework. The calculations demonstrate that the deposition of the Pt atomic thin films on gold substrate results in strong modifications of the electronic structure at the surface. In particular, the Au(111 s-p-type Shockley surface state becomes completely unoccupied at deposition of any number of Pt monolayers. The Pt adlayer generates numerous quantum-well states in various energy gaps of Au(111 with strong spatial confinement at the surface. As a result, strong enhancement in the local density of state at the surface Pt atomic layer in comparison with clean Pt surface is obtained. The excess in the density of states has maximal magnitude in the case of one monolayer Pt adlayer and gradually reduces with increasing number of Pt atomic layers. The spin–orbit coupling produces strong modification of the energy dispersion of the electronic states generated by the Pt adlayer and gives rise to certain quantum states with a characteristic Dirac-cone shape.

  17. A study of growth and thermal dewetting behavior of ultra-thin gold films using transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    Sudheer

    2017-07-01

    Full Text Available The growth and solid-state dewetting behavior of Au thin films (0.7 to 8.4 nm deposited on the formvar film (substrate by sputtering technique have been studied using transmission electron microscopy. The size and number density of the Au nanoparticles (NPs change with an increase in the film thickness (0.7 to 2.8 nm. Nearly spherical Au NPs are obtained for 6 nm show capability to be used as an irreversible temperature sensor with a sensitivity of ∼0.1 CAF/°C. It is observed that annealing affects the crystallinity of the Au grains in the films. The electron diffraction measurement also shows annealing induced morphological evolution in the percolated Au thin films (≥3 nm during solid-state dewetting and recrystallization of the grains.

  18. Structure analysis of ultra-thin films. STM/AFM. Chousumaku no kozo kaiseki. STM/AFM

    Energy Technology Data Exchange (ETDEWEB)

    Nozoe, H; Yumura, M [National Institute of Materials and Chemical Research, Tsukuba (Japan)

    1994-03-30

    Fullerene (C60) and carbon nanotubes are expected as new carbon structures. This article describes the observation results of C60 and carbon nanotubes by means of STM (scanning tunnel microscope). The STM images of C60 thin films are illustrated, which have been obtained by annealing at 290 centigrade. It was confirmed that C60 monomolecular thin films are formed which conform to the substrate and have high regularity. The step height of C60 monomolecular thin films coincided with the step height of Cu (111) plane, which suggested that the step of films is reflected in that of Cu substrate. For the STM images under bias voltages, various images of C60 with three-fold axis of symmetry were observed. On the other hand, from STM observation of carbon nanotubes with diameter of about 30 nm which were separated and purified from the cathode deposits during the preparation process of C60, it was found that they have concentric multilayer structure. 18 refs., 7 figs.

  19. The impact of ultra-thin titania interlayers on open circuit voltage and carrier lifetime in thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Moerman, David; Colbert, Adam E.; Ginger, David S., E-mail: ginger@chem.washington.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Kim, Hyungchul; Graham, Samuel, E-mail: sgraham@gatech.edu [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2016-03-14

    We study the effects of modifying indium tin oxide electrodes with ultrathin titania (TiO{sub 2}) layers grown via plasma-enhanced atomic layer deposition (PE-ALD). We find an optimal thickness of PE-ALD-grown titania by tracking performance, which initially increases, peaks, and eventually decreases with increasing TiO{sub 2} thickness. We use scanning Kelvin probe microscopy (SKPM) to measure both the local work function and its distribution as a function of TiO{sub 2} thickness. We find that the variance in contact potential difference across the surface of the film is related to either the amorphous or anatase TiO{sub 2} form. Finally, we use local SKPM recombination rate experiments, supported by bulk transient photovoltage and charge extraction measurements. We show that the optimum TiO{sub 2} thickness is the one for which the carrier lifetime is the longest and the charge carrier density is the highest, when the TiO{sub 2} is amorphous, in agreement with the device measurements.

  20. The impact of ultra-thin titania interlayers on open circuit voltage and carrier lifetime in thin film solar cells

    International Nuclear Information System (INIS)

    Moerman, David; Colbert, Adam E.; Ginger, David S.; Kim, Hyungchul; Graham, Samuel

    2016-01-01

    We study the effects of modifying indium tin oxide electrodes with ultrathin titania (TiO_2) layers grown via plasma-enhanced atomic layer deposition (PE-ALD). We find an optimal thickness of PE-ALD-grown titania by tracking performance, which initially increases, peaks, and eventually decreases with increasing TiO_2 thickness. We use scanning Kelvin probe microscopy (SKPM) to measure both the local work function and its distribution as a function of TiO_2 thickness. We find that the variance in contact potential difference across the surface of the film is related to either the amorphous or anatase TiO_2 form. Finally, we use local SKPM recombination rate experiments, supported by bulk transient photovoltage and charge extraction measurements. We show that the optimum TiO_2 thickness is the one for which the carrier lifetime is the longest and the charge carrier density is the highest, when the TiO_2 is amorphous, in agreement with the device measurements.

  1. Oxidation behaviors of the TiNi/Ti_2Ni matrix composite coatings with different contents of TaC addition fabricated on Ti6Al4V by laser cladding

    International Nuclear Information System (INIS)

    Lv, Y.H.; Li, J.; Tao, Y.F.; Hu, L.F.

    2016-01-01

    The TiNi/Ti_2Ni matrix composite coatings were fabricated on Ti6Al4V by laser cladding the mixtures of NiCrBSi and different contents of TaC (0 wt%, 5 wt%, 15 wt%, 30 wt% and 40 wt%). Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffractometry (XRD) were used to examine the microstructures of the coatings. Oxidation behaviors of these coatings were also investigated at 800 °C for 50 h in air. The results showed that the coating without TaC addition was mainly composed of TiNi/Ti_2Ni as the matrix and TiC/TiB_2/TiB as the reinforcement. TaC was dissolved completely and precipitated again during laser cladding. Ta and C from the added TaC mainly existed as the solute atoms in the solid solutions of TiC, TiB_2 and TiB in the coatings with TaC addition. The addition of TaC refined the microstructures of the coatings. In the oxidation test, the oxidation process was divided into the violent oxidation stage and the slow oxidation stage. The oxidation rates of the substrate and the coatings with different contents of TaC (0, 5, 15, 30, 40 wt%) were 0.644, 0.287, 0.173, 0.161, 0.223 and 0.072 mg cm"−"2 h"−"1 in the first stage, 0.884, 0.215, 0.136, 0.126, 0.108 and 0.040 mg"2 cm"−"4 h"−"1 in the second stage, respectively. The weight gain of these samples were 6.70, 3.30, 2.86, 2.64, 2.41 and 1.69 mg cm"−"2, respectively after the whole oxidation test. The oxidation film formed on the surface of the coating without TaC addition mainly consisted of TiO_2, Al_2O_3, and a small amount of NiO, Cr_2O_3 and SiO_2. Moreover, Ta_2O_5 was also formed on the surfaces of these coatings with different contents of TaC. The oxides formed during the oxidation test were supposed to be responsible for the improvement in oxidation resistance of these coatings. - Highlights: • The composite coatings with TaC addition were fabricated on Ti6Al4V by laser cladding. • Effect of TaC addition on microstructural evolution of the coatings was

  2. Oxidation behaviors of the TiNi/Ti{sub 2}Ni matrix composite coatings with different contents of TaC addition fabricated on Ti6Al4V by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Y.H.; Li, J., E-mail: jacob_lijun@sina.com; Tao, Y.F.; Hu, L.F.

    2016-09-15

    The TiNi/Ti{sub 2}Ni matrix composite coatings were fabricated on Ti6Al4V by laser cladding the mixtures of NiCrBSi and different contents of TaC (0 wt%, 5 wt%, 15 wt%, 30 wt% and 40 wt%). Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffractometry (XRD) were used to examine the microstructures of the coatings. Oxidation behaviors of these coatings were also investigated at 800 °C for 50 h in air. The results showed that the coating without TaC addition was mainly composed of TiNi/Ti{sub 2}Ni as the matrix and TiC/TiB{sub 2}/TiB as the reinforcement. TaC was dissolved completely and precipitated again during laser cladding. Ta and C from the added TaC mainly existed as the solute atoms in the solid solutions of TiC, TiB{sub 2} and TiB in the coatings with TaC addition. The addition of TaC refined the microstructures of the coatings. In the oxidation test, the oxidation process was divided into the violent oxidation stage and the slow oxidation stage. The oxidation rates of the substrate and the coatings with different contents of TaC (0, 5, 15, 30, 40 wt%) were 0.644, 0.287, 0.173, 0.161, 0.223 and 0.072 mg cm{sup −2} h{sup −1} in the first stage, 0.884, 0.215, 0.136, 0.126, 0.108 and 0.040 mg{sup 2} cm{sup −4} h{sup −1} in the second stage, respectively. The weight gain of these samples were 6.70, 3.30, 2.86, 2.64, 2.41 and 1.69 mg cm{sup −2}, respectively after the whole oxidation test. The oxidation film formed on the surface of the coating without TaC addition mainly consisted of TiO{sub 2}, Al{sub 2}O{sub 3}, and a small amount of NiO, Cr{sub 2}O{sub 3} and SiO{sub 2}. Moreover, Ta{sub 2}O{sub 5} was also formed on the surfaces of these coatings with different contents of TaC. The oxides formed during the oxidation test were supposed to be responsible for the improvement in oxidation resistance of these coatings. - Highlights: • The composite coatings with TaC addition were fabricated on Ti6Al4V by laser

  3. Ultra-thin g-C{sub 3}N{sub 4} nanosheets wrapped silicon nanowire array for improved chemical stability and enhanced photoresponse

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Beibei; Yu, Hongtao; Quan, Xie, E-mail: quanxie@dlut.edu.cn; Chen, Shuo

    2014-11-15

    Highlights: • g-C{sub 3}N{sub 4}, as an oxygen free and metal free protective material for Si, was proposed. • g-C{sub 3}N{sub 4} nanosheets wrapped Si nanowire array was synthesized. • SiNW/g-C{sub 3}N{sub 4} exhibited enhancement of photoelectrochemical stability and photocurrent. - Abstract: In order to inhibit the oxidation of Si materials in aqueous solution, Si nanowire array was wrapped by ultra-thin g-C{sub 3}N{sub 4} nanosheets via an electrophoresis process. Scanning electron microscopy and transmission electron microscopy images showed that g-C{sub 3}N{sub 4} nanosheets were evenly distributed on the surface of Si nanowire array. X-ray diffraction patterns indicated that Si nanowire array/g-C{sub 3}N{sub 4} nanosheets were composed of Si (4 0 0 crystal plane) and g-C{sub 3}N{sub 4} (0 0 2 and 1 0 0 crystal planes). The cyclic voltammetry curves revealed that the corrosion of Si nanowire array was restrained under the protection of g-C{sub 3}N{sub 4} nanosheets. Furthermore, the photocurrent density of Si nanowire array/g-C{sub 3}N{sub 4} nanosheets increased by nearly 3 times compared to that of bare Si nanowire array due to the effective charge separation caused by the built-in electric field at the interface. This work will facilitate the applications of Si materials in aqueous solution, such as solar energy harvest and photocatalytic pollution control.

  4. Effect of mating materials on wear properties of amorphous hydrogenated carbon (a-C:H coating and tetrahedral amorphous carbon (ta-C coating in base oil boundary lubrication condition

    Directory of Open Access Journals (Sweden)

    Xiang Li

    2017-12-01

    Full Text Available In this study, wear behavior of amorphous hydrogenated carbon (a-C:H coating and tetrahedral amorphous carbon (ta-C coating when sliding against various mating materials in base oil boundary lubrication condition is comparatively investigated to find out the optimal combinations of DLC/mating material and corresponding wear mechanism of both DLC coating. Tribological tests were performed in a cylinder-on-disc tribometer, Field Emission Scanning Electron Microscopy, Raman spectroscopy is used for characterization of ta-C and a-C:H worn surface. The results show that the specific wear rate of ta-C coating increases along with the hardness and roughness of mating material increases, while the specific wear rate of a-C:H coating increases together with an increment in the ID/IG ratio. It is concluded that for ta-C coating, local stress concentration-induced microfracture is the main wear mechanism in relative high wear scenario, along with minor graphitization-induced wear which prevails in low wear scenario. On the other hand, a-C:H coating showed that simultaneous generation and removal of the graphitized layer on the contact surface is the predominant wear mechanism.

  5. Tribological properties of amorphous hydrogenated (a-C:H) and hydrogen-free tetrahedral (ta-C) diamond-like carbon coatings under jatropha biodegradable lubricating oil at different temperatures

    International Nuclear Information System (INIS)

    Mobarak, H.M.; Masjuki, H.H.; Mohamad, E. Niza; Kalam, M.A.; Rashedul, H.K.; Rashed, M.M.; Habibullah, M.

    2014-01-01

    Highlights: • We tested a-C:H and ta-C DLC coatings as a function of temperature. • Jatropha oil contains large amounts of polar components that enhanced the lubricity of coatings. • CoF decreases with increasing temperature for both contacts. • Wear rate increases with increasing temperature in a-C:H and decreases in ta-C DLC. • At high temperature, ta-C coatings confer more protection than a-C:H coatings. - Abstract: The application of diamond-like carbon (DLC) coatings on automotive components is emerging as a favorable strategy to address the recent challenges in the industry. DLC coatings can effectively lower the coefficient of friction (CoF) and wear rate of engine components, thereby improving their fuel efficiency and durability. The lubrication of ferrous materials can be enhanced by a large amount of unsaturated and polar components of oils. Therefore, the interaction between nonferrous coatings (e.g., DLC) and vegetable oil should be investigated. A ball-on-plate tribotester was used to run the experiments. Stainless steel plates coated with amorphous hydrogenated (a-C:H) DLC and hydrogen-free tetrahedral (ta-C) DLC that slide against 440C stainless steel ball were used to create a ball-on-plate tribotester. The wear track was investigated through scanning electron microscopy. Energy dispersive and X-ray photoelectron spectroscopies were used to analyze the tribofilm inside the wear track. Raman analysis was performed to investigate the structural changes in the coatings. At high temperatures, the CoF in both coatings decreased. The wear rate, however, increased in the a-C:H but decreased in the ta-C DLC-coated plates. The CoF and the wear rate (coated layer and counter surface) were primarily influenced by the graphitization of the coating. Tribochemical films, such as polyphosphate glass, were formed in ta-C and acted as protective layers. Therefore, the wear rate of the ta-C DLC was lower than that of the-C:H DLC

  6. Tribological properties of amorphous hydrogenated (a-C:H) and hydrogen-free tetrahedral (ta-C) diamond-like carbon coatings under jatropha biodegradable lubricating oil at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mobarak, H.M., E-mail: mobarak.ho31@yahoo.com; Masjuki, H.H.; Mohamad, E. Niza, E-mail: edzrol@um.edu.my; Kalam, M.A.; Rashedul, H.K.; Rashed, M.M.; Habibullah, M.

    2014-10-30

    Highlights: • We tested a-C:H and ta-C DLC coatings as a function of temperature. • Jatropha oil contains large amounts of polar components that enhanced the lubricity of coatings. • CoF decreases with increasing temperature for both contacts. • Wear rate increases with increasing temperature in a-C:H and decreases in ta-C DLC. • At high temperature, ta-C coatings confer more protection than a-C:H coatings. - Abstract: The application of diamond-like carbon (DLC) coatings on automotive components is emerging as a favorable strategy to address the recent challenges in the industry. DLC coatings can effectively lower the coefficient of friction (CoF) and wear rate of engine components, thereby improving their fuel efficiency and durability. The lubrication of ferrous materials can be enhanced by a large amount of unsaturated and polar components of oils. Therefore, the interaction between nonferrous coatings (e.g., DLC) and vegetable oil should be investigated. A ball-on-plate tribotester was used to run the experiments. Stainless steel plates coated with amorphous hydrogenated (a-C:H) DLC and hydrogen-free tetrahedral (ta-C) DLC that slide against 440C stainless steel ball were used to create a ball-on-plate tribotester. The wear track was investigated through scanning electron microscopy. Energy dispersive and X-ray photoelectron spectroscopies were used to analyze the tribofilm inside the wear track. Raman analysis was performed to investigate the structural changes in the coatings. At high temperatures, the CoF in both coatings decreased. The wear rate, however, increased in the a-C:H but decreased in the ta-C DLC-coated plates. The CoF and the wear rate (coated layer and counter surface) were primarily influenced by the graphitization of the coating. Tribochemical films, such as polyphosphate glass, were formed in ta-C and acted as protective layers. Therefore, the wear rate of the ta-C DLC was lower than that of the-C:H DLC.

  7. Spin dynamics and frequency dependence of magnetic damping study in soft ferromagnetic FeTaC film with a stripe domain structure

    Energy Technology Data Exchange (ETDEWEB)

    Samantaray, B., E-mail: iitg.biswanath@gmail.com; Ranganathan, R.; Mandal, P. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064 (India); Singh, Akhilesh K.; Perumal, A. [Department of Physics, Indian Institute of Technology Guwahati, Guwahati - 781039 (India)

    2015-06-15

    Perpendicular magnetic anisotropy (PMA) and low magnetic damping are the key factors for the free layer magnetization switching by spin transfer torque technique in magnetic tunnel junction devices. The magnetization precessional dynamics in soft ferromagnetic FeTaC thin film with a stripe domain structure was explored in broad band frequency range by employing micro-strip ferromagnetic resonance technique. The polar angle variation of resonance field and linewidth at different frequencies have been analyzed numerically using Landau-Lifshitz-Gilbert equation by taking into account the total free energy density of the film. The numerically estimated parameters Landé g-factor, PMA constant, and effective magnetization are found to be 2.1, 2 × 10{sup 5} erg/cm{sup 3} and 7145 Oe, respectively. The frequency dependence of Gilbert damping parameter (α) is evaluated by considering both intrinsic and extrinsic effects into the total linewidth analysis. The value of α is found to be 0.006 at 10 GHz and it increases monotonically with decreasing precessional frequency.

  8. Nitrogen doping for adhesion improvement of DLC film deposited on Si substrate by Filtered Cathodic Vacuum Arc (FCVA) technique

    Energy Technology Data Exchange (ETDEWEB)

    Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Supsermpol, B.; Saenphinit, N. [Western Digital Company, Ayutthaya 13160 (Thailand); Aramwit, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50202 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50202 (Thailand)

    2014-08-15

    Diamond-like carbon (DLC) films have been used in many applications due to their attractive combination of properties including chemical inertness, corrosion protection, biocompatibility, high hardness, and low wear rates. However, they still have some limitations such as high internal stresses and low toughness which lead to poor adhesion of films. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these limitations. In this study, DLC films, namely tetrahedral amorphous carbon (ta-C) and nitrogen doped tetrahedral amorphous carbon (ta-C:N) were deposited on single crystalline Si wafer substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. Film characterizations were carried out by Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), triboindenter tester and nano-scratch tester. Measurement results showed that intentionally doping with nitrogen reduced the carbon sp{sup 3} content and increased the surface roughness in comparison with that of pure ta-C films. The hardness measurement confirmed the Raman and AFM analyses that adding nitrogen in ta-C films decreased the hardness, especially with high nitrogen content. However, the nano-scratch test revealed the increasing of the critical load with nitrogen. This work, then, extended its scope to investigate the properties of double-layer ta-C films which were composed of ta-C:N interlayer of various thickness around 10–30 nm and ta-C top-layer with thickness of around 80 nm. Microstructure characterization demonstrated that a ta-C:N interlayer gradually decreased the sp{sup 3} fraction in the films and increased film roughness whenever the ta-C:N interlayer thickness increased. In this structure, the tribological property in terms of adhesion to the Si substrate was significantly improved by about 20–90%, but the mechanical property in terms of hardness was gradually degraded by about 2–10%, compared to pure ta-C film, when the ta-C

  9. High-resolution structural studies of ultra-thin magnetic, transition metal overlayers and two-dimensional transition metal oxides using synchrotron radiation

    International Nuclear Information System (INIS)

    Kellar, S.A.; Lawrence Berkeley National Lab., CA

    1997-05-01

    This thesis report the surface-structure determination of three, ultra-thin magnetic transition-metal films, Fe/Au(100), Mn/Ni(100), and Mn/Cu(100) using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) and photoelectron holography. These structural studies are the first to use non-s initial states in the ARPEFS procedure. This thesis also reports an ARPEFS surface-structure determination of a two-dimensional transition-metal oxide, [(1 x 1)O/W(110)] x 12. The authors have analyzed the ARPFES signal from the Au 4f 7/5 core level of the Au(1 ML)/Fe(15 ML)/Au(100) system. The analysis shows that the Fe grows layer by layer with one monolayer of gold, acting as a surfactant, remaining on top of the growing Fe layers. These surface gold atoms sit in the four-fold hollow site, 1.67 ± 0.02 A above the iron surface. The grown Fe layer is very much like the bulk, bcc iron, with an interlayer spacing of 1.43 ± 0.03 A. Analysis of the Mn 3p ARPEFS signals from c(2 x 2)Mn/Ni(100) and c(2 x 2)Mn/Cu(100) shows that the Mn forms highly corrugated surface alloys. The corrugation of the Mn/Ni(100) and Mn/Cu(100) systems are 0.24 ± 0.02 A and 0.30 ± 0.04 A respectively. In both cases the Mn is sticking above the plane of the surface substrate atoms. For the Mn/Ni(100) system the first layer Ni is contracted 4% from the bulk value. The Mn/Cu(100) system shows bulk spacing for the substrate Cu. Photoelectron holography shows that the Mn/Ni interface is very abrupt with very little Mn leaking into the second layer, while the Mn/Cu(100) case has a significant amount of Mn leaking into the second layer. A new, five-element electrostatic electron lens was developed for hemispherical electron-energy analyzers. This lens system can be operated at constant transverse or constants angular magnification, and has been optimized for use with the very small photon-spot sizes. Improvements to the hemispherical electron-energy analyzer are also discussed

  10. High-resolution structural studies of ultra-thin magnetic, transition metal overlayers and two-dimensional transition metal oxides using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kellar, S.A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.

    1997-05-01

    This thesis report the surface-structure determination of three, ultra-thin magnetic transition-metal films, Fe/Au(100), Mn/Ni(100), and Mn/Cu(100) using Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) and photoelectron holography. These structural studies are the first to use non-s initial states in the ARPEFS procedure. This thesis also reports an ARPEFS surface-structure determination of a two-dimensional transition-metal oxide, [(1 x 1)O/W(110)] x 12. The authors have analyzed the ARPFES signal from the Au 4f{sub 7/5} core level of the Au(1 ML)/Fe(15 ML)/Au(100) system. The analysis shows that the Fe grows layer by layer with one monolayer of gold, acting as a surfactant, remaining on top of the growing Fe layers. These surface gold atoms sit in the four-fold hollow site, 1.67 {+-} 0.02 A above the iron surface. The grown Fe layer is very much like the bulk, bcc iron, with an interlayer spacing of 1.43 {+-} 0.03 A. Analysis of the Mn 3p ARPEFS signals from c(2 x 2)Mn/Ni(100) and c(2 x 2)Mn/Cu(100) shows that the Mn forms highly corrugated surface alloys. The corrugation of the Mn/Ni(100) and Mn/Cu(100) systems are 0.24 {+-} 0.02 A and 0.30 {+-} 0.04 A respectively. In both cases the Mn is sticking above the plane of the surface substrate atoms. For the Mn/Ni(100) system the first layer Ni is contracted 4% from the bulk value. The Mn/Cu(100) system shows bulk spacing for the substrate Cu. Photoelectron holography shows that the Mn/Ni interface is very abrupt with very little Mn leaking into the second layer, while the Mn/Cu(100) case has a significant amount of Mn leaking into the second layer. A new, five-element electrostatic electron lens was developed for hemispherical electron-energy analyzers. This lens system can be operated at constant transverse or constants angular magnification, and has been optimized for use with the very small photon-spot sizes. Improvements to the hemispherical electron-energy analyzer are also discussed.

  11. Anatase TiO2 hierarchical structures composed of ultra-thin nano-sheets exposing high percentage {0 0 1} facets and their application in quantum-dot sensitized solar cells

    International Nuclear Information System (INIS)

    Wu, Dapeng; Zhang, Shuo; Jiang, Shiwei; He, Jinjin; Jiang, Kai

    2015-01-01

    Graphical abstract: TiO 2 hierarchical structures assembled from ultra-thin nanosheets exposing ∼90% {0 0 1} facets were employed as photoanode materials to improve the performance of CdS/CdSe co-sensitized solar cells. - Highlights: • THSs composited of nanosheets exposing high percent {0 0 1} facets were prepared. • THSs improve the QDs loading amount and light scattering of the photoanode. • THSs suppress the carrier recombination and finally lead to ∼25% PCE improvement. - Abstract: TiO 2 hierarchical structures (THSs) composed of ultra-thin nano-sheets exposing ∼90% {0 0 1} facets were prepared via a hydrothermal method. Time dependent trails revealed the formation of THSs experienced a self-assemble process. The as-prepared product were used as the photoanode materials for CdS/CdSe co-sensitized solar cells, and the THSs/nanoparticle hybrid photoanode demonstrated a power conversion efficiency of 3.47%, indicating ∼25% improvement compared with the nanoparticle cell

  12. Ultra-thin silicon oxide layers on crystalline silicon wafers: Comparison of advanced oxidation techniques with respect to chemically abrupt SiO{sub 2}/Si interfaces with low defect densities

    Energy Technology Data Exchange (ETDEWEB)

    Stegemann, Bert, E-mail: bert.stegemann@htw-berlin.de [HTW Berlin - University of Applied Sciences, 12459 Berlin (Germany); Gad, Karim M. [University of Freiburg, Department of Microsystems Engineering - IMTEK, 79110 Freiburg (Germany); Balamou, Patrice [HTW Berlin - University of Applied Sciences, 12459 Berlin (Germany); Helmholtz Center Berlin for Materials and Energy (HZB), 12489 Berlin (Germany); Sixtensson, Daniel [Helmholtz Center Berlin for Materials and Energy (HZB), 12489 Berlin (Germany); Vössing, Daniel; Kasemann, Martin [University of Freiburg, Department of Microsystems Engineering - IMTEK, 79110 Freiburg (Germany); Angermann, Heike [Helmholtz Center Berlin for Materials and Energy (HZB), 12489 Berlin (Germany)

    2017-02-15

    Highlights: • Fabrication of ultrathin SiO{sub 2} tunnel layers on c-Si. • Correlation of electronic and chemical SiO{sub 2}/Si interface properties revealed by XPS/SPV. • Chemically abrupt SiO{sub 2}/Si interfaces generate less interface defect states considerable. - Abstract: Six advanced oxidation techniques were analyzed, evaluated and compared with respect to the preparation of high-quality ultra-thin oxide layers on crystalline silicon. The resulting electronic and chemical SiO{sub 2}/Si interface properties were determined by a combined x-ray photoemission (XPS) and surface photovoltage (SPV) investigation. Depending on the oxidation technique, chemically abrupt SiO{sub 2}/Si interfaces with low densities of interface states were fabricated on c-Si either at low temperatures, at short times, or in wet-chemical environment, resulting in each case in excellent interface passivation. Moreover, the beneficial effect of a subsequent forming gas annealing (FGA) step for the passivation of the SiO{sub 2}/Si interface of ultra-thin oxide layers has been proven. Chemically abrupt SiO{sub 2}/Si interfaces have been shown to generate less interface defect states.

  13. Study of first electronic transition and hydrogen bonding state of ultra-thin water layer of nanometer thickness on an α-alumina surface by far-ultraviolet spectroscopy

    Science.gov (United States)

    Goto, Takeyoshi; Kinugasa, Tomoya

    2018-05-01

    The first electronic transition (A˜ ← X˜) and the hydrogen bonding state of an ultra-thin water layer of nanometer thickness between two α-alumina surfaces (0.5-20 nm) were studied using far-ultraviolet (FUV) spectroscopy in the wavelength range 140-180 nm. The ultra-thin water layer of nanometer thickness was prepared by squeezing a water droplet ( 1 μL) between a highly polished α-alumina prism and an α-alumina plate using a high pressure clamp ( 4.7 MPa), and the FUV spectra of the water layer at different thicknesses were measured using the attenuated total reflection method. As the water layer became thinner, the A˜ ← X˜ bands were gradually shifted to higher or lower energy relative to that of bulk water; at thicknesses smaller than 4 nm, these shifts were substantial (0.1-0.2 eV) in either case. The FUV spectra of the water layer with thickness lost at thicknesses below 4 nm, because of steric hydration forces between the α-alumina surfaces.

  14. Anatase TiO{sub 2} hierarchical structures composed of ultra-thin nano-sheets exposing high percentage {0 0 1} facets and their application in quantum-dot sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dapeng, E-mail: dpengwu@126.com [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Henan Province for Green Motive Power and Key Materials, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang, Henan 453007 (China); Zhang, Shuo; Jiang, Shiwei; He, Jinjin [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Jiang, Kai [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Henan Province for Green Motive Power and Key Materials, Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang, Henan 453007 (China)

    2015-03-05

    Graphical abstract: TiO{sub 2} hierarchical structures assembled from ultra-thin nanosheets exposing ∼90% {0 0 1} facets were employed as photoanode materials to improve the performance of CdS/CdSe co-sensitized solar cells. - Highlights: • THSs composited of nanosheets exposing high percent {0 0 1} facets were prepared. • THSs improve the QDs loading amount and light scattering of the photoanode. • THSs suppress the carrier recombination and finally lead to ∼25% PCE improvement. - Abstract: TiO{sub 2} hierarchical structures (THSs) composed of ultra-thin nano-sheets exposing ∼90% {0 0 1} facets were prepared via a hydrothermal method. Time dependent trails revealed the formation of THSs experienced a self-assemble process. The as-prepared product were used as the photoanode materials for CdS/CdSe co-sensitized solar cells, and the THSs/nanoparticle hybrid photoanode demonstrated a power conversion efficiency of 3.47%, indicating ∼25% improvement compared with the nanoparticle cell.

  15. Tribological properties of amorphous hydrogenated (a-C:H) and hydrogen-free tetrahedral (ta-C) diamond-like carbon coatings under jatropha biodegradable lubricating oil at different temperatures

    Science.gov (United States)

    Mobarak, H. M.; Masjuki, H. H.; Mohamad, E. Niza; Kalam, M. A.; Rashedul, H. K.; Rashed, M. M.; Habibullah, M.

    2014-10-01

    The application of diamond-like carbon (DLC) coatings on automotive components is emerging as a favorable strategy to address the recent challenges in the industry. DLC coatings can effectively lower the coefficient of friction (CoF) and wear rate of engine components, thereby improving their fuel efficiency and durability. The lubrication of ferrous materials can be enhanced by a large amount of unsaturated and polar components of oils. Therefore, the interaction between nonferrous coatings (e.g., DLC) and vegetable oil should be investigated. A ball-on-plate tribotester was used to run the experiments. Stainless steel plates coated with amorphous hydrogenated (a-C:H) DLC and hydrogen-free tetrahedral (ta-C) DLC that slide against 440C stainless steel ball were used to create a ball-on-plate tribotester. The wear track was investigated through scanning electron microscopy. Energy dispersive and X-ray photoelectron spectroscopies were used to analyze the tribofilm inside the wear track. Raman analysis was performed to investigate the structural changes in the coatings. At high temperatures, the CoF in both coatings decreased. The wear rate, however, increased in the a-C:H but decreased in the ta-C DLC-coated plates. The CoF and the wear rate (coated layer and counter surface) were primarily influenced by the graphitization of the coating. Tribochemical films, such as polyphosphate glass, were formed in ta-C and acted as protective layers. Therefore, the wear rate of the ta-C DLC was lower than that of the-C:H DLC.

  16. Transition metal carbides (WC, Mo2C, TaC, NbC) as potential electrocatalysts for the hydrogen evolution reaction (HER) at medium temperatures

    DEFF Research Database (Denmark)

    Meyer, Simon; Nikiforov, Aleksey V.; Petrushina, Irina M.

    2015-01-01

    One limitation for large scale water electrolysis is the high price of the Pt cathode catalyst. Transition metal carbides, which are considered as some of the most promising non-Pt catalysts, are less active than Pt at room temperature. The present work demonstrates that the situation is different......C > TaC. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved....

  17. Effect of high substrate bias and hydrogen and nitrogen incorporation on filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films

    International Nuclear Information System (INIS)

    Panwar, O.S.; Khan, Mohd. Alim; Kumar, Mahesh; Shivaprasad, S.M.; Satyanarayana, B.S.; Dixit, P.N.; Bhattacharyya, R.; Khan, M.Y.

    2008-01-01

    The application of a sufficiently high negative substrate bias, during the growth of tetrahedral amorphous carbon (ta-C), is usually associated with low sp 3 bonding configuration and stressed films. However, in an effort to understand and utilize the higher pseudo thermo dynamical conditions during the film growth, at high negative substrate bias (- 300 V), reported here is a study on ta-C films grown under different hydrogen and nitrogen concentration. As grown ta-C films were studied under different negative substrate bias conditions. The variation of the sp 3 content and sp 3 /sp 2 ratio in the ta-C films exhibits a trend similar to those reported in literature, with a subtle variation in this report being the substrate bias voltage, which was observed to be around - 200 V, for obtaining the highest sp 3 (80%) bonding and sp 3 /sp 2 (3.95) ratio. The hydrogen and nitrogen incorporated ta-C films studied, at a bias of - 300 V, show an increase in sp 3 (87-91%) bonding and sp 3 /sp 2 (7-10) ratio in the range of studies reported. The inference is drawn on the basis of the set of data obtained from measurements carried out using X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy and Raman spectroscopy of as grown and hydrogen and nitrogen incorporated ta-C films deposited using an S bend filtered cathodic vacuum arc system. The study indicates the possibility of further tailoring ta-C film properties and also extending capabilities of the cathodic arc system for developing carbon based films for electronics and tribological applications

  18. Effect of high substrate bias and hydrogen and nitrogen incorporation on filtered cathodic vacuum arc deposited tetrahedral amorphous carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India)], E-mail: ospanwar@mail.nplindia.ernet.in; Khan, Mohd. Alim [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Kumar, Mahesh; Shivaprasad, S.M. [Surface Physics and Nanostructures Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Satyanarayana, B.S. [MIT Innovation Centre and Electronics and Communication Department, Manipal Institute of Technology, Manipal-579104 (India); Dixit, P.N. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi-110 012 (India); Bhattacharyya, R. [Emeritus Scientist, National Physical Laboratory, New Delhi-110012 (India); Khan, M.Y. [Department of Physics, Jamia Millia Islamia, Central University, New Delhi-110025 (India)

    2008-02-29

    The application of a sufficiently high negative substrate bias, during the growth of tetrahedral amorphous carbon (ta-C), is usually associated with low sp{sup 3} bonding configuration and stressed films. However, in an effort to understand and utilize the higher pseudo thermo dynamical conditions during the film growth, at high negative substrate bias (- 300 V), reported here is a study on ta-C films grown under different hydrogen and nitrogen concentration. As grown ta-C films were studied under different negative substrate bias conditions. The variation of the sp{sup 3} content and sp{sup 3}/sp{sup 2} ratio in the ta-C films exhibits a trend similar to those reported in literature, with a subtle variation in this report being the substrate bias voltage, which was observed to be around - 200 V, for obtaining the highest sp{sup 3} (80%) bonding and sp{sup 3}/sp{sup 2} (3.95) ratio. The hydrogen and nitrogen incorporated ta-C films studied, at a bias of - 300 V, show an increase in sp{sup 3} (87-91%) bonding and sp{sup 3}/sp{sup 2} (7-10) ratio in the range of studies reported. The inference is drawn on the basis of the set of data obtained from measurements carried out using X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy and Raman spectroscopy of as grown and hydrogen and nitrogen incorporated ta-C films deposited using an S bend filtered cathodic vacuum arc system. The study indicates the possibility of further tailoring ta-C film properties and also extending capabilities of the cathodic arc system for developing carbon based films for electronics and tribological applications.

  19. Study on influences of TiN capping layer on time-dependent dielectric breakdown characteristic of ultra-thin EOT high- k metal gate NMOSFET with kMC TDDB simulations

    International Nuclear Information System (INIS)

    Xu Hao; Yang Hong; Luo Wei-Chun; Xu Ye-Feng; Wang Yan-Rong; Tang Bo; Wang Wen-Wu; Qi Lu-Wei; Li Jun-Feng; Yan Jiang; Zhu Hui-Long; Zhao Chao; Chen Da-Peng; Ye Tian-Chun

    2016-01-01

    The thickness effect of the TiN capping layer on the time dependent dielectric breakdown (TDDB) characteristic of ultra-thin EOT high- k metal gate NMOSFET is investigated in this paper. Based on experimental results, it is found that the device with a thicker TiN layer has a more promising reliability characteristic than that with a thinner TiN layer. From the charge pumping measurement and secondary ion mass spectroscopy (SIMS) analysis, it is indicated that the sample with the thicker TiN layer introduces more Cl passivation at the IL/Si interface and exhibits a lower interface trap density. In addition, the influences of interface and bulk trap density ratio N it / N ot are studied by TDDB simulations through combining percolation theory and the kinetic Monte Carlo (kMC) method. The lifetime reduction and Weibull slope lowering are explained by interface trap effects for TiN capping layers with different thicknesses. (paper)

  20. Preparation of ultra-thin and high-quality WO{sub 3} compact layers and comparision of WO{sub 3} and TiO{sub 2} compact layer thickness in planar perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jincheng; Shi, Chengwu, E-mail: shicw506@foxmail.com; Chen, Junjun; Wang, Yanqing; Li, Mingqian

    2016-06-15

    In this paper, the ultra-thin and high-quality WO{sub 3} compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO{sub 3} and TiO{sub 2} compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO{sub 2} compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO{sub 3} and TiO{sub 2} compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. - Graphical abstract: The planar perovskite solar cell with 15 nm WO{sub 3} compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO{sub 2} compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency. Display Omitted - Highlights: • Preparation of ultra-thin and high-quality WO{sub 3} compact layers. • Perovskite solar cell with 15 nm-thick WO{sub 3} compact layer achieved PCE of 10.14%. • Perovskite solar cell with 60 nm-thick TiO{sub 2} compact layer achieved PCE of 12.64%.

  1. Interfacial engineering of two-dimensional nano-structured materials by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhuiykov, Serge, E-mail: serge.zhuiykov@ugent.be [Ghent University Global Campus, Department of Applied Analytical & Physical Chemistry, Faculty of Bioscience Engineering, 119 Songdomunhwa-ro, Yeonsu-Gu, Incheon 406-840 (Korea, Republic of); Kawaguchi, Toshikazu [Global Station for Food, Land and Water Resources, Global Institution for Collaborative Research and Education, Hokkaido University, N10W5 Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Graduate School of Environmental Science, Hokkaido University, N10W5 Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Hai, Zhenyin; Karbalaei Akbari, Mohammad; Heynderickx, Philippe M. [Ghent University Global Campus, Department of Applied Analytical & Physical Chemistry, Faculty of Bioscience Engineering, 119 Songdomunhwa-ro, Yeonsu-Gu, Incheon 406-840 (Korea, Republic of)

    2017-01-15

    Highlights: • Advantages of atomic layer deposition technology (ALD) for two-dimensional nano-crystals. • Conformation of ALD technique and chemistry of precursors. • ALD of semiconductor oxide thin films. • Ultra-thin (∼1.47 nm thick) ALD-developed tungsten oxide nano-crystals on large area. - Abstract: Atomic Layer Deposition (ALD) is an enabling technology which provides coating and material features with significant advantages compared to other existing techniques for depositing precise nanometer-thin two-dimensional (2D) nanostructures. It is a cyclic process which relies on sequential self-terminating reactions between gas phase precursor molecules and a solid surface. ALD is especially advantageous when the film quality or thickness is critical, offering ultra-high aspect ratios. ALD provides digital thickness control to the atomic level by depositing film one atomic layer at a time, as well as pinhole-free films even over a very large and complex areas. Digital control extends to sandwiches, hetero-structures, nano-laminates, metal oxides, graded index layers and doping, and it is perfect for conformal coating and challenging 2D electrodes for various functional devices. The technique’s capabilities are presented on the example of ALD-developed ultra-thin 2D tungsten oxide (WO{sub 3}) over the large area of standard 4” Si substrates. The discussed advantages of ALD enable and endorse the employment of this technique for the development of hetero-nanostructure 2D semiconductors with unique properties.

  2. Carbonized tantalum catalysts for catalytic chemical vapor deposition of silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Shimin [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Dalian National Laboratory for Clean Energy, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Gao Huiping; Ren Tong; Ying Pinliang [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Dalian National Laboratory for Clean Energy, Dalian 116023 (China); Li Can, E-mail: canli@dicp.ac.cn [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Dalian National Laboratory for Clean Energy, Dalian 116023 (China)

    2012-06-01

    Catalytic chemical vapor deposition (Cat-CVD) has been demonstrated as a promising way to prepare device-quality silicon films. However, catalyst ageing due to Si contamination is an urgency to be solved for the practical application of the technique. In this study, the effect of carbonization of tantalum catalyst on its structure and performance was investigated. The carbonized Ta catalyst has a TaC surface layer which is preserved over the temperature range between 1450 and 1750 Degree-Sign C and no Si contamination occurs on the catalyst after long-term use. Si film prepared using the carbonized Ta catalyst has a similar crystal structure to that prepared by uncarbonized Ta catalyst. Formation of the TaC surface layer can alleviate the ageing problem of the catalyst, which shows great potential as a stable catalyst for Cat-CVD of Si films. - Highlights: Black-Right-Pointing-Pointer Si films prepared by catalytic chemical vapor deposition. Black-Right-Pointing-Pointer Carbonized Ta with a TaC surface layer used as catalyst. Black-Right-Pointing-Pointer TaC surface structure preserved after long-term use in a wide temperature range. Black-Right-Pointing-Pointer Help to solve the ageing problem of metal catalysts. Black-Right-Pointing-Pointer Si film obtained has a similar crystal structure to that prepared by Ta catalyst.

  3. Secondary ion emission from ultra-thin oxide layers bombarded by energetic (MeV) heavy ions: depth of origin and layer homogeneity

    International Nuclear Information System (INIS)

    Allali, H.; Nsouli, B.; Thomas, J.P.; Cabaud, B.; Fuchs, G.; Hoareau, A.; Treilleux, M.; Danel, J.S.

    1993-09-01

    The escape depth of the secondary ions resulting from electronic sputtering of fast heavy ions in inorganic thin films has been investigated. Chromium layers deposited onto SiO 2 substrate as well as SiO x layers deposited onto chromium substrate have been characterized by secondary ion emission mass spectrometry (SIMS) in combination with time-of-flight (TOF) mass analysis (also referred as HSF-SIMS). These crossed experiments lead to a value around 1 nm for SiO x layers and 0.5 nm for Cr layers. On the other hand, HSF-SIMS can be used to correlate the intensity of the secondary ion emission to the film coverage rate and (or) the morphology of particular films like those produced by Low Energy Cluster Beam Deposition (LECBD). Using Sb deposits, the non-linear relationship between ion emission and coverage is interpreted in terms of sputtering enhancement in the individual supported clusters. (author) 22 refs., 9 figs., 1 tab

  4. XPS and STEM study of the interface formation between ultra-thin Ru and Ir OER catalyst layers and perylene red support whiskers

    Directory of Open Access Journals (Sweden)

    Atanasoska Ljiljana L.

    2013-01-01

    Full Text Available The interface formation between nano-structured perylene red (PR whiskers and oxygen evolution reaction (OER catalysts ruthenium and iridium has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. STEM images demonstrate that, with increasing thickness, Ru and Ir transform from amorphous clusters to crystalline nanoparticles, which agglomerate with increased over-layer thickness. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent.

  5. Metallic Limus-Eluting Stents Abluminally Coated with Biodegradable Polymers: Angiographic and Clinical Comparison of a Novel Ultra-Thin Sirolimus Stent Versus Biolimus Stent in the DESTINY Randomized Trial.

    Science.gov (United States)

    Lemos, Pedro A; Abizaid, Alexandre A C; Meireles, George C; Sarmento-Leite, Rogério; Prudente, Mauricio; Cantarelli, Marcelo; Dourado, Adriano D; Mariani, Jose; Perin, Marco A; Costantini, Costantino; Costa, Ricardo A; Costa, José Ribamar; Chamie, Daniel; Campos, Carlos A; Ribeiro, Expedito

    2015-12-01

    To evaluate the outcomes of patients treated with a new drug-eluting stent formulation with low doses of sirolimus, built in an ultra-thin-strut platform coated with biodegradable abluminal coating. This study is a randomized trial that tested the main hypothesis that the angiographic late lumen loss of the novel sirolimus-eluting stent is noninferior compared with commercially available biolimus-eluting stent. A final study population comprising 170 patients with one or two de novo lesions was randomized in the ratio 2:1 for sirolimus-eluting stent or biolimus-eluting stent, respectively. The primary endpoint was 9-month angiographic in-stent late lumen loss. Adverse clinical events were prospectively collected for 1 year. After 9 months, the novel sirolimus-eluting stent was shown noninferior compared with the biolimus stent for the primary endpoint (angiographic in-stent late lumen loss: 0.20 ± 0.29 mm vs. 0.15 ± 0.20 mm, respectively; P value for noninferiority <0.001). The 1-year incidence of death, myocardial infarction, repeat revascularization, and stent thrombosis remained low and not significantly different between the groups. The present randomized trial demonstrates that the tested novel sirolimus-eluting stent was angiographically noninferior in comparison with a last-generation biolimus-eluting stent. © 2015 John Wiley & Sons Ltd.

  6. Multi-step cure kinetic model of ultra-thin glass fiber epoxy prepreg exhibiting both autocatalytic and diffusion-controlled regimes under isothermal and dynamic-heating conditions

    Science.gov (United States)

    Kim, Ye Chan; Min, Hyunsung; Hong, Sungyong; Wang, Mei; Sun, Hanna; Park, In-Kyung; Choi, Hyouk Ryeol; Koo, Ja Choon; Moon, Hyungpil; Kim, Kwang J.; Suhr, Jonghwan; Nam, Jae-Do

    2017-08-01

    As packaging technologies are demanded that reduce the assembly area of substrate, thin composite laminate substrates require the utmost high performance in such material properties as the coefficient of thermal expansion (CTE), and stiffness. Accordingly, thermosetting resin systems, which consist of multiple fillers, monomers and/or catalysts in thermoset-based glass fiber prepregs, are extremely complicated and closely associated with rheological properties, which depend on the temperature cycles for cure. For the process control of these complex systems, it is usually required to obtain a reliable kinetic model that could be used for the complex thermal cycles, which usually includes both the isothermal and dynamic-heating segments. In this study, an ultra-thin prepreg with highly loaded silica beads and glass fibers in the epoxy/amine resin system was investigated as a model system by isothermal/dynamic heating experiments. The maximum degree of cure was obtained as a function of temperature. The curing kinetics of the model prepreg system exhibited a multi-step reaction and a limited conversion as a function of isothermal curing temperatures, which are often observed in epoxy cure system because of the rate-determining diffusion of polymer chain growth. The modified kinetic equation accurately described the isothermal behavior and the beginning of the dynamic-heating behavior by integrating the obtained maximum degree of cure into the kinetic model development.

  7. Influencia de las adiciones de TaC y NbC en las propiedades de los aceros rápidos pulvimetalúrgicos M3/2

    Directory of Open Access Journals (Sweden)

    Gordo, E.

    2002-04-01

    Full Text Available Metal matrix composites based on M3/2 high speed steel and reinforced with different percentages of NbC and TaC were manufactured following a conventional powder metallurgy route: mixing, compacting and sintering. Graphite, to compensate carbon losses during sintering, and copper-phosphorous, to promote liquid phase sintering, were added to M3/2 powders to constitute the base material. Carbide and base material powders were dry mixed and uniaxially compacted at 700 MPa. After this, vacuum sintering was carried out at two temperatures: 1190 °C and 1230 °C. The mechanical properties and wear behaviour of all sintered materials were examined, and their characterisation was completed with a broad microstructural study

    Este trabajo plantea la fabricación de materiales compuestos de matriz metálica, basados en el acero rápido M3/2 y reforzados con distintas cantidades de NbC y TaC, mediante técnicas convencionales pulvimetalúrgicas (P/M: mezcla, compactación y sinterización. Al acero rápido se añadió grafito para compensar las pérdidas de carbono durante la sinterización y cupro-fósforo para promover sinterización en fase líquida, constituyendo esta mezcla el material base. Los polvos de carburos y de material base fueron mezclados en seco y compactados uniaxialmente a 700 MPa. Tras esta etapa, se realizó la sinterización en vacío a dos temperaturas: 1.190 °C y 1.230 °C. Todos los materiales sinterizados fueron caracterizados mediante el estudio de las propiedades mecánicas, el comportamiento a desgaste y un amplio análisis microestructural.

  8. Matrix shaped pulsed laser deposition: New approach to large area and homogeneous deposition

    Energy Technology Data Exchange (ETDEWEB)

    Akkan, C.K.; May, A. [INM – Leibniz Institute for New Materials, CVD/Biosurfaces Group, Campus D2 2, 66123 Saarbrücken (Germany); Hammadeh, M. [Department for Obstetrics, Gynecology and Reproductive Medicine, IVF Laboratory, Saarland University Medical Center and Faculty of Medicine, Building 9, 66421 Homburg, Saar (Germany); Abdul-Khaliq, H. [Clinic for Pediatric Cardiology, Saarland University Medical Center and Faculty of Medicine, Building 9, 66421 Homburg, Saar (Germany); Aktas, O.C., E-mail: cenk.aktas@inm-gmbh.de [INM – Leibniz Institute for New Materials, CVD/Biosurfaces Group, Campus D2 2, 66123 Saarbrücken (Germany)

    2014-05-01

    Pulsed laser deposition (PLD) is one of the well-established physical vapor deposition methods used for synthesis of ultra-thin layers. Especially PLD is suitable for the preparation of thin films of complex alloys and ceramics where the conservation of the stoichiometry is critical. Beside several advantages of PLD, inhomogeneity in thickness limits use of PLD in some applications. There are several approaches such as rotation of the substrate or scanning of the laser beam over the target to achieve homogenous layers. On the other hand movement and transition create further complexity in process parameters. Here we present a new approach which we call Matrix Shaped PLD to control the thickness and homogeneity of deposited layers precisely. This new approach is based on shaping of the incoming laser beam by a microlens array and a Fourier lens. The beam is split into much smaller multi-beam array over the target and this leads to a homogenous plasma formation. The uniform intensity distribution over the target yields a very uniform deposit on the substrate. This approach is used to deposit carbide and oxide thin films for biomedical applications. As a case study coating of a stent which has a complex geometry is presented briefly.

  9. Optimization of nanoparticulate indium tin oxide slurries for the manufacture of ultra-thin indium tin oxide coatings with the slot-die coating process

    International Nuclear Information System (INIS)

    Wegener, M.; Riess, K.; Roosen, A.

    2016-01-01

    This paper deals with the optimization of colloidal processing to achieve suitable nanoparticulate indium tin oxide (ITO) slurries for the production of sub-μm-thin ITO coatings with the slot die coating process. For application in printed electronics these ITO coatings, which are composite films consisting of nanoparticulate ITO and a polymeric binder, should offer high flexibility, transparency and electrical conductivity. To preserve their flexibility, the composite films are not subject to any heat treatment, instead they are used as deposited and dried. To achieve very good transparency and electrical conductivity at the same time, the slurries must exhibit excellent dispersivity to result in a dense particle packing during film formation and drying. To reduce materials costs, films with thicknesses of several 100 nm are of interest. Therefore, the slot-die technique was applied as a fast, pre-dosing technique to produce sub-μm-thin ITO/binder composite films. The resulting ITO/binder films were characterized with regard to their key properties such as total transmission and specific electrical resistance. With the colloidal optimization of ethanol- and water-based nanoparticulate ITO slurries using PVP and PVB as binders, it was possible to achieve films of 250 nm in thickness exhibiting high total transmission of ∝ 93 % and a low specific electrical resistance of ∝ 10 Ω.cm.

  10. Interfacial Energy Alignment at the ITO/Ultra-Thin Electron Selective Dielectric Layer Interface and Its Effect on the Efficiency of Bulk-Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Itoh, Eiji; Goto, Yoshinori; Saka, Yusuke; Fukuda, Katsutoshi

    2016-04-01

    We have investigated the photovoltaic properties of an inverted bulk heterojunction (BHJ) cell in a device with an indium-tin-oxide (ITO)/electron selective layer (ESL)/P3HT:PCBM active layer/MoOx/Ag multilayered structure. The insertion of only single layer of poly(diallyl-dimethyl-ammonium chloride) (PDDA) cationic polymer film (or poly(ethyleneimine) (PEI) polymeric interfacial dipole layer) and titanium oxide nanosheet (TN) films as an ESL effectively improved cell performance. Abnormal S-shaped curves were observed in the inverted BHJ cells owing to the contact resistance across the ITO/active layer interface and the ITO/PDDA/TN/active layer interface. The series resistance across the ITO/ESL interface in the inverted BHJ cell was successfully reduced using an interfacial layer with a positively charged surface potential with respect to ITO base electrode. The positive dipole in PEI and the electronic charge phenomena at the electrophoretic deposited TN (ED-TN) films on ITO contributed to the reduction of the contact resistance at the electrode interface. The surface potential measurement revealed that the energy alignment by the transfer of electronic charges from the ED-TN to the base electrodes. The insertion of the ESL with a large positive surface potential reduced the potential barrier for the electron injection at ITO/TN interface and it improved the photovoltaic properties of the inverted cell with an ITO/TN/active layer/MoOx/Ag structure.

  11. Growth and characterization of epitaxial ultra-thin NbN films on 3C-SiC/Si substrate for terahertz applications

    International Nuclear Information System (INIS)

    Dochev, D; Desmaris, V; Pavolotsky, A; Meledin, D; Belitsky, V; Lai, Z; Henry, A; Janzen, E; Pippel, E; Woltersdorf, J

    2011-01-01

    We report on electrical properties and microstructure of epitaxial thin NbN films grown on 3C-SiC/Si substrates by means of reactive magnetron sputtering. A complete epitaxial growth at the NbN/3C-SiC interface has been confirmed by means of high resolution transmission electron microscopy (HRTEM) along with x-ray diffractometry (XRD). Resistivity measurements of the films have shown that the superconducting transition onset temperature (T C ) for the best specimen is 11.8 K. Using these epitaxial NbN films, we have fabricated submicron-size hot-electron bolometer (HEB) devices on 3C-SiC/Si substrate and performed their complete DC characterization. The observed critical temperature T C = 11.3 K and critical current density of about 2.5 MA cm -2 at 4.2 K of the submicron-size bridges were uniform across the sample. This suggests that the deposited NbN films possess the necessary homogeneity to sustain reliable hot-electron bolometer device fabrication for THz mixer applications.

  12. Growth and characterization of epitaxial ultra-thin NbN films on 3C-SiC/Si substrate for terahertz applications

    Energy Technology Data Exchange (ETDEWEB)

    Dochev, D; Desmaris, V; Pavolotsky, A; Meledin, D; Belitsky, V [Group for Advanced Receiver Development, Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Lai, Z [Nanofabrication Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Henry, A; Janzen, E [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Pippel, E; Woltersdorf, J, E-mail: dimitar.dochev@chalmers.se [Max-Planck-Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

    2011-03-15

    We report on electrical properties and microstructure of epitaxial thin NbN films grown on 3C-SiC/Si substrates by means of reactive magnetron sputtering. A complete epitaxial growth at the NbN/3C-SiC interface has been confirmed by means of high resolution transmission electron microscopy (HRTEM) along with x-ray diffractometry (XRD). Resistivity measurements of the films have shown that the superconducting transition onset temperature (T{sub C}) for the best specimen is 11.8 K. Using these epitaxial NbN films, we have fabricated submicron-size hot-electron bolometer (HEB) devices on 3C-SiC/Si substrate and performed their complete DC characterization. The observed critical temperature T{sub C} = 11.3 K and critical current density of about 2.5 MA cm{sup -2} at 4.2 K of the submicron-size bridges were uniform across the sample. This suggests that the deposited NbN films possess the necessary homogeneity to sustain reliable hot-electron bolometer device fabrication for THz mixer applications.

  13. Optimization of nanoparticulate indium tin oxide slurries for the manufacture of ultra-thin indium tin oxide coatings with the slot-die coating process

    Energy Technology Data Exchange (ETDEWEB)

    Wegener, M.; Riess, K.; Roosen, A. [Erlangen-Nuremberg Univ., Erlangen (Germany). Dept. of Materials Science, Glass and Ceramics

    2016-07-01

    This paper deals with the optimization of colloidal processing to achieve suitable nanoparticulate indium tin oxide (ITO) slurries for the production of sub-μm-thin ITO coatings with the slot die coating process. For application in printed electronics these ITO coatings, which are composite films consisting of nanoparticulate ITO and a polymeric binder, should offer high flexibility, transparency and electrical conductivity. To preserve their flexibility, the composite films are not subject to any heat treatment, instead they are used as deposited and dried. To achieve very good transparency and electrical conductivity at the same time, the slurries must exhibit excellent dispersivity to result in a dense particle packing during film formation and drying. To reduce materials costs, films with thicknesses of several 100 nm are of interest. Therefore, the slot-die technique was applied as a fast, pre-dosing technique to produce sub-μm-thin ITO/binder composite films. The resulting ITO/binder films were characterized with regard to their key properties such as total transmission and specific electrical resistance. With the colloidal optimization of ethanol- and water-based nanoparticulate ITO slurries using PVP and PVB as binders, it was possible to achieve films of 250 nm in thickness exhibiting high total transmission of ∝ 93 % and a low specific electrical resistance of ∝ 10 Ω.cm.

  14. Impact of laser power density on tribological properties of Pulsed Laser Deposited DLC films

    Science.gov (United States)

    Gayathri, S.; Kumar, N.; Krishnan, R.; AmirthaPandian, S.; Ravindran, T. R.; Dash, S.; Tyagi, A. K.; Sridharan, M.

    2013-12-01

    Fabrication of wear resistant and low friction carbon films on the engineered substrates is considered as a challenging task for expanding the applications of diamond-like carbon (DLC) films. In this paper, pulsed laser deposition (PLD) technique is used to deposit DLC films on two different types of technologically important class of substrates such as silicon and AISI 304 stainless steel. Laser power density is one of the important parameter used to tailor the fraction of sp2 bonded amorphous carbon (a-C) and tetrahedral amorphous carbon (ta-C) made by sp3 domain in the DLC film. The I(D)/I(G) ratio decreases with the increasing laser power density which is associated with decrease in fraction of a-C/ta-C ratio. The fraction of these chemical components is quantitatively analyzed by EELS which is well supported to the data obtained from the Raman spectroscopy. Tribological properties of the DLC are associated with chemical structure of the film. However, the super low value of friction coefficient 0.003 is obtained when the film is predominantly constituted by a-C and sp2 fraction which is embedded within the clusters of ta-C. Such a particular film with super low friction coefficient is measured while it was deposited on steel at low laser power density of 2 GW/cm2. The super low friction mechanism is explained by low sliding resistance of a-C/sp2 and ta-C clusters. Combination of excellent physical and mechanical properties of wear resistance and super low friction coefficient of DLC films is desirable for engineering applications. Moreover, the high friction coefficient of DLC films deposited at 9GW/cm2 is related to widening of the intergrain distance caused by transformation from sp2 to sp3 hybridized structure.

  15. Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition

    Directory of Open Access Journals (Sweden)

    Adib Abou Chaaya

    2013-10-01

    Full Text Available A study of transmittance and photoluminescence spectra on the growth of oxygen-rich ultra-thin ZnO films prepared by atomic layer deposition is reported. The structural transition from an amorphous to a polycrystalline state is observed upon increasing the thickness. The unusual behavior of the energy gap with thickness reflected by optical properties is attributed to the improvement of the crystalline structure resulting from a decreasing concentration of point defects at the growth of grains. The spectra of UV and visible photoluminescence emissions correspond to transitions near the band-edge and defect-related transitions. Additional emissions were observed from band-tail states near the edge. A high oxygen ratio and variable optical properties could be attractive for an application of atomic layer deposition (ALD deposited ultrathin ZnO films in optical sensors and biosensors.

  16. Enhancement of TE polarized light extraction efficiency in nanoscale (AlN)m /(GaN)n (m>n) superlattice substitution for Al-rich AlGaN disorder alloy: ultra-thin GaN layer modulation

    International Nuclear Information System (INIS)

    Jiang, Xin-he; Shi, Jun-jie; Zhong, Hong-xia; Huang, Pu; Ding, Yi-min; Yu, Tong-jun; Shen, Bo; Lu, Jing; Zhang, Min; Wang, Xihua

    2014-01-01

    The problem of achieving high light extraction efficiency in Al-rich Al x Ga 1−x N is of paramount importance for the realization of AlGaN-based deep ultraviolet (DUV) optoelectronic devices. To solve this problem, we investigate the microscopic mechanism of valence band inversion and light polarization, a crucial factor for enhancing light extraction efficiency, in Al-rich Al x Ga 1−x N alloy using the Heyd–Scuseria–Ernzerhof hybrid functional, local-density approximation with 1/2 occupation, and the Perdew–Burke–Ernzerhof functional, in which the spin–orbit coupling effect is included. We find that the microscopic Ga-atom distribution can effectively modulate the valence band structure of Al-rich Al x Ga 1−x N. Moreover, we prove that the valence band arrangement in the decreasing order of heavy hole, light hole, and crystal-field split-off hole can be realized by using nanoscale (AlN) m /(GaN) n (m>n) superlattice (SL) substituting for Al-rich Al x Ga 1−x N disorder alloy as the active layer of optoelectronic devices due to the ultra-thin GaN layer modulation. The valence band maximum, i.e., the heavy hole band, has p x - and p y -like characteristics and is highly localized in the SL structure, which leads to the desired transverse electric (TE) polarized (E⊥c) light emission with improved light extraction efficiency in the DUV spectral region. Some important band-structure parameters and electron/hole effective masses are also given. The physical origin for the valence band inversion and TE polarization in (AlN) m /(GaN) n SL is analyzed in depth. (paper)

  17. Uniform deposition of uranium hexafluoride (UF6): Standardized mass deposits and controlled isotopic ratios using a thermal fluorination method.

    Science.gov (United States)

    McNamara, Bruce K; O'Hara, Matthew J; Casella, Andrew M; Carter, Jennifer C; Addleman, R Shane; MacFarlan, Paul J

    2016-07-01

    We report a convenient method for the generation of volatile uranium hexafluoride (UF6) from solid uranium oxides and other U compounds, followed by uniform deposition of low levels of UF6 onto sampling coupons. Under laminar flow conditions, UF6 is shown to interact with surfaces within a fixed reactor geometry to a highly predictable degree. We demonstrate the preparation of U deposits that range between approximately 0.01 and 500ngcm(-2). The data suggest the method can be extended to creating depositions at the sub-picogramcm(-2) level. The isotopic composition of the deposits can be customized by selection of the U source materials and we demonstrate a layering technique whereby two U solids, each with a different isotopic composition, are employed to form successive layers of UF6 on a surface. The result is an ultra-thin deposit that bears an isotopic signature that is a composite of the two U sources. The reported deposition method has direct application to the development of unique analytical standards for nuclear safeguards and forensics. Further, the method allows access to very low atomic or molecular coverages of surfaces. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Uniform deposition of uranium hexafluoride (UF6): Standardized mass deposits and controlled isotopic ratios using a thermal fluorination method

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, Bruce K.; O’Hara, Matthew J.; Casella, Andrew M.; Carter, Jennifer C.; Addleman, R. Shane; MacFarlan, Paul J.

    2016-07-01

    Abstract: We report a convenient method for the generation of volatile uranium hexafluoride (UF6) from solid uranium oxides and other uranium compounds, followed by uniform deposition of low levels of UF6 onto sampling coupons. Under laminar flow conditions, UF6 is shown to interact with surfaces within the chamber to a highly predictable degree. We demonstrate the preparation of uranium deposits that range between ~0.01 and 470±34 ng∙cm-2. The data suggest the method can be extended to creating depositions at the sub-picogram∙cm-2 level. Additionally, the isotopic composition of the deposits can be customized by selection of the uranium source materials. We demonstrate a layering technique whereby two uranium solids, each with a different isotopic composition, are employed to form successive layers of UF6 on a surface. The result is an ultra-thin deposit of UF6 that bears an isotopic signature that is a composite of the two uranium sources. The reported deposition method has direct application to the development of unique analytical standards for nuclear safeguards and forensics.

  19. Stress-induced leakage current characteristics of PMOS fabricated by a new multi-deposition multi-annealing technique with full gate last process

    International Nuclear Information System (INIS)

    Wang Yanrong; Yang Hong; Xu Hao; Luo Weichun; Qi Luwei; Zhang Shuxiang; Wang Wenwu; Zhu Huilong; Zhao Chao; Chen Dapeng; Ye Tianchun; Yan Jiang

    2017-01-01

    In the process of high- k films fabrication, a novel multi deposition multi annealing (MDMA) technique is introduced to replace simple post deposition annealing. The leakage current decreases with the increase of the post deposition annealing (PDA) times. The equivalent oxide thickness (EOT) decreases when the annealing time(s) change from 1 to 2. Furthermore, the characteristics of SILC (stress-induced leakage current) for an ultra-thin SiO 2 /HfO 2 gate dielectric stack are studied systematically. The increase of the PDA time(s) from 1 to 2 can decrease the defect and defect generation rate in the HK layer. However, increasing the PDA times to 4 and 7 may introduce too much oxygen, therefore the type of oxygen vacancy changes. (paper)

  20. Superhard carbon film deposition by means of Laser-Arco {sup registered} on the way from the laboratory into the industrial series coating; Abscheidung superharter Kohlenstoffschichten mittels Laser-Arco {sup registered} auf dem Weg vom Labor in die industrielle Serienfertigung

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Hans-Joachim; Leonhardt, Michael; Leson, Andreas; Meyer, Carl-Friedrich; Stucky, Thomas; Weihnacht, Volker [Fraunhofer-Institut fuer Werkstoff- und Strahltechnik (IWS), Dresden (Germany)

    2008-12-15

    Diamond-like carbon films (DLC) are more and more applied as wear protection coatings for components and tools due to their unique combination of high hardness, low friction and sticking tendency to metallic counter bodies. Up to now applied DLC films are hydrogen containing (a-C:H) or metal carbon films (Me-C:H) deposited by a plasma assisted CVD process from carbon-hydrogen gas mixtures. Their wide industrial effort results from that the can be deposited with slowly modified coating machines for classical hard coating (e.g. TiN or CrN). A new generation DLC films are the hydrogen-free ta-C films (ta-C = tetrahedral bounded amorphous carbon) with a between two and three-times higher hardness and with a resulting higher wear resistance under extreme condition than classical DLC films. They have excellent emergency running properties at lubrication break down. Their industrial application is more difficult due to that they cannot deposited with modified coating machines for classical hard and DLC coating and a new technology with corresponding equipment was not available up to now. The laser controlled, pulsed arc deposition technology (Laser-Arco {sup registered}) of the Fraunhofer IWS Dresden has this potential. In kind of a Laser-Arc-Module-source the ta-C film deposition can be integrated in every industrial used deposition machine. (orig.)

  1. Low field leakage current on ultra-thin gate oxides after ion or electron beam irradiations; Courant de fuite aux champs faibles d'oxydes ultra-minces apres irradiations avec des faisceaux d'ions et d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Ceschia, M.; Paccagnella, A.; Sandrin, S. [Universita di Padova, Dipt. di Elettronica e Informatica, Padova (Italy); Paccagnella, A. [Istituto Nazionale per la Fisica della Materia, INFM, Unita di Padova (Italy); Ghidini, G. [ST-Microelectronics, Agrate Brianza (Italy); Wyss, J. [Universita di Padova, Dipt. di Fisica, Padova (Italy)

    1999-07-01

    In contemporary CMOS 0.25-{mu}m technologies, the MOS gate oxide (thickness {approx_equal} 5 nm) shows a low-field leakage current after radiation stresses, i.e. the radiation induced leakage current (RILC). RILC is generally attributed to a trap assisted tunneling (TAT) of electrons through neutral oxide traps generated by radiation stress. RILC has been investigated on ultra-thin oxides irradiated with 158 MeV {sup 28}Si ions or 8 MeV electrons. 3 main results are worth being quoted: 1) ion or electron beam irradiation can produce RILC with similar characteristics. Even the dose dependence of RILC is similar in the 2 cases, despite the large LET difference (about a factor of 10{sup +4}), 2) RILC is not a constant as a function of time, it tends to decrease when an oxide field (few MV/cm) is applied for (tens of) thousands seconds. On the other hand, RILC stays constant in devices kept at low bias, and 3) if a pulsed gate voltage is applied during irradiation, RILC is reduced with respect to the zero-field case. (A.C.)

  2. Self-limiting atomic layer deposition of conformal nanostructured silver films

    International Nuclear Information System (INIS)

    Golrokhi, Zahra; Chalker, Sophia; Sutcliffe, Christopher J.; Potter, Richard J.

    2016-01-01

    Graphical abstract: - Highlights: • We grow metallic silver by direct liquid injection thermal atomic layer deposition. • Highly conformal silver nanoparticle coatings on high aspect ratio surfaces. • An ALD temperature growth window between 123 and 128 °C is established. • ALD cycles provides sub nanometre control of silver growth. • Catalytic dehydrogenation ALD mechanism has been elucidated by in-situ QCM. - Abstract: The controlled deposition of ultra-thin conformal silver nanoparticle films is of interest for applications including anti-microbial surfaces, plasmonics, catalysts and sensors. While numerous techniques can produce silver nanoparticles, few are able to produce highly conformal coatings on high aspect ratio surfaces, together with sub-nanometre control and scalability. Here we develop a self-limiting atomic layer deposition (ALD) process for the deposition of conformal metallic silver nanoparticle films. The films have been deposited using direct liquid injection ALD with ((hexafluoroacetylacetonato)silver(I)(1,5-cyclooctadiene)) and propan-1-ol. An ALD temperature window between 123 and 128 °C is identified and within this range self-limiting growth is confirmed with a mass deposition rate of ∼17.5 ng/cm"2/cycle. The effects of temperature, precursor dose, co-reactant dose and cycle number on the deposition rate and on the properties of the films have been systematically investigated. Under self-limiting conditions, films are metallic silver with a nano-textured surface topography and nanoparticle size is dependent on the number of ALD cycles. The ALD reaction mechanisms have been elucidated using in-situ quartz crystal microbalance (QCM) measurements, showing chemisorption of the silver precursor, followed by heterogeneous catalytic dehydrogenation of the alcohol to form metallic silver and an aldehyde.

  3. Surface modification of cadmium sulfide thin film honey comb nanostructures: Effect of in situ tin doping using chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, K.C., E-mail: wilsonphy@gmail.com [Department of Physics, Govt. Polytechnic College Kothamangalam, Chelad P O, Ernakulam, Kerala 686681 (India); Department of Physics, B. S. Abdur Rahman University, Vandaloor, Chennai, Tamilnadu 600048 (India); Basheer Ahamed, M. [Department of Physics, B. S. Abdur Rahman University, Vandaloor, Chennai, Tamilnadu 600048 (India)

    2016-01-15

    Graphical abstract: - Highlights: • Novel honey comb like cadmium sulfide thin film nanostructures prepared using chemical bath deposition on glass substrates. • Honey comb nanostructure found in two layers: an ultra thin film at bottom and well inter connected with walls of < 25 nm thick on top; hence maximum surface area possible for CdS nanostructure. • Shell size of the nanostructures and energy band gaps were controlled also an enhanced persistent conductivity observed on Sn doping. - Abstract: Even though nanostructures possess large surface to volume ratio compared to their thin film counterpart, the complicated procedure that demands for the deposition on a substrate kept them back foot in device fabrication techniques. In this work, a honey comb like cadmium sulfide (CdS) thin films nanostructure are deposited on glass substrates using simple chemical bath deposition technique at 65 °C. Energy band gaps, film thickness and shell size of the honey comb nanostructures are successfully controlled using tin (Sn) doping and number of shells per unit area is found to be maximum for 5% Sn doped (in the reaction mixture) sample. X-ray diffraction and optical absorption analysis showed that cadmium sulfide and cadmium hydroxide coexist in the samples. TEM measurements showed that CdS nanostructures are embedded in cadmium hydroxide just like “plum pudding”. Persistent photoconductivity measurements of the samples are also carried out. The decay constants found to be increased with increases in Sn doping.

  4. Optimizing AlF{sub 3} atomic layer deposition using trimethylaluminum and TaF{sub 5}: Application to high voltage Li-ion battery cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, David H. K., E-mail: david.jackson@wisc.edu; Kuech, Thomas F. [Materials Science Program, University of Wisconsin–Madison, Madison, Wisconsin 53706 and Department of Chemical and Biological Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Laskar, Masihhur R.; Ellis, Ryan G. [Department of Chemical and Biological Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Fang, Shuyu; Hamers, Robert J. [Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Xu, Shenzhen; Li, Xiaoqing; Morgan, Dane [Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Dreibelbis, Mark [Core R& D, Inorganic Materials and Heterogeneous Catalysis, The Dow Chemical Company, Midland, Michigan 48674 (United States); Babcock, Susan E. [Materials Science Program, University of Wisconsin–Madison, Madison, Wisconsin 53706 and Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Mahanthappa, Mahesh K. [Materials Science Program, University of Wisconsin–Madison, Madison, Wisconsin 53706 and Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States)

    2016-05-15

    Atomic layer deposition (ALD) of conformal AlF{sub 3} coatings onto both flat silicon substrates and high-voltage LiNi{sub 0.5}Mn{sub 0.3}Co{sub 0.2}O{sub 2} (NMC) Li-ion battery cathode powders was investigated using a Al(CH{sub 3}){sub 3}/TaF{sub 5} precursor combination. This optimized approach employs easily handled ALD precursors, while also obviating the use of highly toxic HF(g). In studies conducted on planar Si wafers, the film's growth mode was dictated by a competition between the desorption and decomposition of Ta reaction byproducts. At T ≥ 200 °C, a rapid decomposition of the Ta reaction byproducts to TaC led to continuous deposition and high concentrations of TaC in the films. A self-limited ALD growth mode was found to occur when the deposition temperature was reduced to 125 °C, and the TaF{sub 5} exposures were followed by an extended purge. The lower temperature process suppressed conversion of TaF{sub x}(CH{sub 3}){sub 5−x} to nonvolatile TaC, and the long purges enabled nearly complete TaF{sub x}(CH{sub 3}){sub 5−x} desorption, leaving behind the AlF{sub 3} thin films. NMC cathode powders were coated using these optimized conditions, and coin cells employing these coated cathode particles exhibited significant improvements in charge capacity fade at high discharge rates.

  5. The properties of TiN ultra-thin films grown on SiO{sub 2} substrate by reactive high power impulse magnetron sputtering under various growth angles

    Energy Technology Data Exchange (ETDEWEB)

    Shayestehaminzadeh, S., E-mail: ses30@hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tryggvason, T.K. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Karlsson, L. [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany); Olafsson, S. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Gudmundsson, J.T. [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); University of Michigan-Shanghai Jiao Tong University, University Joint Institute, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China)

    2013-12-02

    Thin TiN films were grown on SiO{sub 2} by reactive high power impulse magnetron sputtering (HiPIMS) and conventional dc magnetron sputtering (dcMS) while varying the angle between the target and the substrate surface from 0° (on-axis growth) to 90° (off-axis growth). Surface morphology and structural characterization were carried out using X-ray diffraction and reflection methods and the film properties were compared. The dcMS process shows higher growth rate than the HiPIMS process for on-axis grown films but the dcMS growth rate drops drastically for off-axis growth while the HiPIMS growth rate decreases slowly with increased angle between target and substrate for off-axis growth and becomes comparable to the dcMS growth rate. The dcMS grown films exhibit angle dependence in the density and surface roughness while the HiPIMS process creates denser and smoother films that are less angle dependent in all aspects. It was observed that the HiPIMS grown films remain poly-crystalline for all angles of rotation while the dcMS grown films are somewhat amorphous after 60°. The [111] and [200] grain sizes are comparable to the total film thickness in the HiPIMS grown films for all angles of rotation. In the case of dcMS, the [111], [200] and [220] grain sizes are roughly of the same size and much smaller than the total thickness for all growth angles except at 60° and higher. - Highlights: • TiN films were grown on SiO{sub 2} by HiPIMS and dcMS under various growth angles. • Influence of growth angle α = 0–90° on deposition rate and film quality was studied. • The HiPIMS process produces denser and smoother films for all growth angles. • At α = 0°, the growth rate of HiPIMS is 25% of dcMS while it is 50% at 90°. • The HiPIMS grown films remain poly-crystalline for all growth angles.

  6. Tsunami deposits

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-15

    The NSC (the Nuclear Safety Commission of Japan) demand to survey on tsunami deposits by use of various technical methods (Dec. 2011), because tsunami deposits have useful information on tsunami activity, tsunami source etc. However, there are no guidelines on tsunami deposit survey in JAPAN. In order to prepare the guideline of tsunami deposits survey and evaluation and to develop the method of tsunami source estimation on the basis of tsunami deposits, JNES carried out the following issues; (1) organizing information of paleoseismological record and tsunami deposit by literature research, (2) field survey on tsunami deposit, and (3) designing the analysis code of sediment transport due to tsunami. As to (1), we organize the information gained about tsunami deposits in the database. As to (2), we consolidate methods for surveying and identifying tsunami deposits in the lake based on results of the field survey in Fukui Pref., carried out by JNES. In addition, as to (3), we design the experimental instrument for hydraulic experiment on sediment transport and sedimentation due to tsunamis. These results are reflected in the guideline on the tsunami deposits survey and evaluation. (author)

  7. Tsunami deposits

    International Nuclear Information System (INIS)

    2013-01-01

    The NSC (the Nuclear Safety Commission of Japan) demand to survey on tsunami deposits by use of various technical methods (Dec. 2011), because tsunami deposits have useful information on tsunami activity, tsunami source etc. However, there are no guidelines on tsunami deposit survey in JAPAN. In order to prepare the guideline of tsunami deposits survey and evaluation and to develop the method of tsunami source estimation on the basis of tsunami deposits, JNES carried out the following issues; (1) organizing information of paleoseismological record and tsunami deposit by literature research, (2) field survey on tsunami deposit, and (3) designing the analysis code of sediment transport due to tsunami. As to (1), we organize the information gained about tsunami deposits in the database. As to (2), we consolidate methods for surveying and identifying tsunami deposits in the lake based on results of the field survey in Fukui Pref., carried out by JNES. In addition, as to (3), we design the experimental instrument for hydraulic experiment on sediment transport and sedimentation due to tsunamis. These results are reflected in the guideline on the tsunami deposits survey and evaluation. (author)

  8. The influence of tertiary butyl hydrazine as a co-reactant on the atomic layer deposition of silver

    Energy Technology Data Exchange (ETDEWEB)

    Golrokhi, Zahra; Marshall, Paul A.; Romani, Simon [Centre for Materials and Structures, School of Engineering,The University of Liverpool, Liverpool L69 3GH (United Kingdom); Rushworth, Simon [EpiValence, The Wilton Centre, Redcar, Cleveland, TS10 4RF (United Kingdom); Chalker, Paul R. [Centre for Materials and Structures, School of Engineering,The University of Liverpool, Liverpool L69 3GH (United Kingdom); Potter, Richard J., E-mail: rjpott@liverpool.ac.uk [Centre for Materials and Structures, School of Engineering,The University of Liverpool, Liverpool L69 3GH (United Kingdom)

    2017-03-31

    Highlights: • We demonstrate metallic silver growth by direct liquid injection thermal ALD. • A substituted hydrazine is used as a powerful reducing agent for the first time. • The hydrazine extends the ALD temperature window compared with alcohol. • Hydrazine promotes a more planar growth mode compared to alcohol. • Film adhesion is improved using hydrazine compared with alcohol. - Abstract: Ultra-thin conformal silver films are the focus of development for applications such as anti-microbial surfaces, optical components and electronic devices. In this study, metallic silver films have been deposited using direct liquid injection thermal atomic layer deposition (ALD) using (hfac)Ag(1,5-COD) ((hexafluoroacetylacetonato)silver(I)(1,5-cyclooctadiene)) as the metal source and tertiary butyl hydrazine (TBH) as a co-reactant. The process provides a 23 °C wide ‘self-limiting’ ALD temperature window between 105 and 128 °C, which is significantly wider than is achievable using alcohol as a co-reactant. A mass deposition rate of ∼20 ng/cm{sup 2}/cycle (∼0.18 Å/cycle) is observed under self-limiting growth conditions. The resulting films are crystalline metallic silver with a near planar film-like morphology which are electrically conductive. By extending the temperature range of the ALD window by the use of TBH as a co-reactant, it is envisaged that the process will be exploitable in a range of new low temperature applications.

  9. Synthesis of few-layer, large area hexagonal-boron nitride by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Glavin, Nicholas R. [Nanoelectronic Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45433 (United States); School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907 (United States); Jespersen, Michael L. [Nanoelectronic Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45433 (United States); University of Dayton Research Institute, 300 College Park, Dayton, OH 45469 (United States); Check, Michael H. [Nanoelectronic Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45433 (United States); Hu, Jianjun [Nanoelectronic Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45433 (United States); University of Dayton Research Institute, 300 College Park, Dayton, OH 45469 (United States); Hilton, Al M. [Nanoelectronic Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45433 (United States); Wyle Laboratories, Dayton, OH 45433 (United States); Fisher, Timothy S. [School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907 (United States); Voevodin, Andrey A. [Nanoelectronic Materials Branch, Air Force Research Laboratory, Wright-Patterson AFB, Dayton, OH 45433 (United States)

    2014-12-01

    Pulsed laser deposition (PLD) has been investigated as a technique for synthesis of ultra-thin, few-layer hexagonal boron nitride (h-BN) thin films on crystalline highly ordered pyrolytic graphite (HOPG) and sapphire (0001) substrates. The plasma-based processing technique allows for increased excitations of deposited atoms due to background nitrogen gas collisional ionizations and extended resonance time of the energetic species presence at the condensation surface. These processes permit growth of thin, polycrystalline h-BN at 700 °C, a much lower temperature than that required by traditional growth methods. Analysis of the as-deposited films reveals epitaxial-like growth on the nearly lattice matched HOPG substrate, resulting in a polycrystalline h-BN film, and amorphous BN (a-BN) on the sapphire substrates, both with thicknesses of 1.5–2 nm. Stoichiometric films with boron-to-nitrogen ratios of unity were achieved by adjusting the background pressure within the deposition chamber and distance between the target and substrate. The reduction in deposition temperature and formation of stoichiometric, large-area h-BN films by PLD provide a process that is easily scaled-up for two-dimensional dielectric material synthesis and also present a possibility to produce very thin and uniform a-BN. - Highlights: • PLD was used to synthesize boron nitride thin films on HOPG and sapphire substrates. • Lattice matched substrate allowed for formation of polycrystalline h-BN. • Nitrogen gas pressure directly controlled film chemistry and structure. • Technique allows for ultrathin, uniform films at reduced processing temperatures.

  10. Exogenous deposits

    International Nuclear Information System (INIS)

    Khasanov, A.Kh.

    1988-01-01

    Exogenous deposits forming as a result of complex exogenous processes, passed under the influence of outside forces on the Earth surface. To them relate physical and chemical weathering, decomposition and decay of mineral masses, redistribution and transportation of material, forming and deposit of new minerals and ores steady on the earth surface conditions

  11. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ajaib [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Schipmann, Susanne [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Mathur, Aakash; Pal, Dipayan [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Sengupta, Amartya [Department of Physics, Indian Institute of Technology Delhi, Delhi 110016 (India); Klemradt, Uwe [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Chattopadhyay, Sudeshna, E-mail: sudeshna@iiti.ac.in [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Discipline of Physics, Indian Institute of Technology Indore, Indore 453552 (India); Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore 453552 (India)

    2017-08-31

    Highlights: • Ultra-thin ZnO films grown on confined polymeric (polystyrene, PS) template. • XRR and GISAXS explore the surface/interfaces structure and morphology of ZnO/PS. • Insights into the growth mechanism of magnetron sputtered ZnO thin film on PS template. • Nucleated disk-like cylindrical particles are the basis of the formation of ZnO layers. • Effect of ZnO film thickness on room temperature PL spectra in ZnO/PS systems. - Abstract: The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2R{sub g} film thickness, where R{sub g} ∼ 20 nm (R{sub g} is the unperturbed radius of gyration of polystyrene, defined by R{sub g} = 0.272 √M{sub 0}, and M{sub 0} is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2–7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  12. Ultra thin films for sensing and heating of microprobes

    NARCIS (Netherlands)

    Gaitas, A.

    2013-01-01

    This dissertation aims to advance the current state of cantilevers with integrated metal thermal and deflection sensing elements. Metallic sensing elements enable the use of alternative substrate materials (such as polymers), that tend to exhibit higher compliance properties and are more robust

  13. Fabrication and electrical characterization of ultra-thin substrate IGBT

    OpenAIRE

    Guhathakurta, Jajnabalkya

    2013-01-01

    Current topics such as electro-mobility and renewable energy demand the development of power devices with high voltage and current ratings along with minimum switching losses. Amongst the power devices in today’s market, IGBTs have gained a lot of significance in this field over its competitors like Power MOSFETS and Thyristors. Today’s industry has recently taken a huge step in this direction to implement the use of thin-wafer technology for fabrication of IGBTs to reduce the on-resistance. ...

  14. Ultra-thin, single-layer polarization rotator

    Directory of Open Access Journals (Sweden)

    T. V. Son

    2016-08-01

    Full Text Available We demonstrate light polarization control over a broad spectral range by a uniform layer of vanadium dioxide as it undergoes a phase transition from insulator to metal. Changes in refractive indices create unequal phase shifts on s- and p-polarization components of incident light, and rotation of linear polarization shows intensity modulation by a factor of 103 when transmitted through polarizers. This makes possible polarization rotation devices as thin as 50 nm that would be activated thermally, optically or electrically.

  15. Ultra thin films of nanocrystalline Ge studied by AFM and ...

    Indian Academy of Sciences (India)

    Unknown

    peak position and an asymmetrical broadening on the lower frequency side when compared with the spectrum of the bulk Ge sample. The shift of the Raman .... resultant fit to Ic(ω) (1) (thin line) and a Lorentzian function (dotted line). Figure 6 shows Raman spectra of the samples B and C. A shoulder at 280 cm–1 can be.

  16. Biased Target Ion Beam Deposition and Nanoskiving for Fabricating NiTi Alloy Nanowires

    Science.gov (United States)

    Hou, Huilong; Horn, Mark W.; Hamilton, Reginald F.

    2016-12-01

    Nanoskiving is a novel nanofabrication technique to produce shape memory alloy nanowires. Our previous work was the first to successfully fabricate NiTi alloy nanowires using the top-down approach, which leverages thin film technology and ultramicrotomy for ultra-thin sectioning. For this work, we utilized biased target ion beam deposition technology to fabricate nanoscale (i.e., sub-micrometer) NiTi alloy thin films. In contrast to our previous work, rapid thermal annealing was employed for heat treatment, and the B2 austenite to R-phase martensitic transformation was confirmed using stress-temperature and diffraction measurements. The ultramicrotome was programmable and facilitated sectioning the films to produce nanowires with thickness-to-width ratios ranging from 4:1 to 16:1. Energy dispersive X-ray spectroscopy analysis confirmed the elemental Ni and Ti make-up of the wires. The findings exposed the nanowires exhibited a natural ribbon-like curvature, which depended on the thickness-to-width ratio. The results demonstrate nanoskiving is a potential nanofabrication technique for producing NiTi alloy nanowires that are continuous with an unprecedented length on the order of hundreds of micrometers.

  17. Metalorganic chemical vapor deposition of iron disulfide and its use for solar energy conversion

    Science.gov (United States)

    Ennaoui, Ahmed; Fiechter, Sebastian; Vogel, Ralf; Giersig, M.; Weller, Horst; Tributsch, Helmut

    1992-12-01

    Thin polycrystalline films of iron disulfide have been grown on different substrates by chemical vapour deposition. The films were characterized using optical absorption and TEM. RBS and EDAX analysis has been used to explore the chemical stoichiometry. XRD and FTIR allowed the identification of both FeS2 phases pyrite and marcasite. A novel method for sensitization of highly porous Ti02 elecrodes with ultra thin (10-20 nm) polycrystalline films of FeS2 (pyrite) is presented. Photoelectrochemical solar cell using the above electrode generated high photovoltage of up to 600mV compared with single crystalline electrode (200 mV). In this device the semiconductor with a small band gap and high absorption coefficient (FeS2 pyrite; EG = 0.9 eV; a = 6 x 105 cm-1) absorbs the light and injects electrons into the conduction band the wide band gap semiconductor (Ti02 anatase; EG = 3.2 eV). Regeneration of holes is taking place by electron transfer from redox system in the electrolyte.

  18. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Science.gov (United States)

    Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

    2017-08-01

    The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  19. Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors

    Science.gov (United States)

    Biyikli, Necmi; Haider, Ali

    2017-09-01

    In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.

  20. TiC含量对WC-TiC-TaC硬质合金材料微观组织及力学性能的影响%Effects of TiC Content on Microstructure and Mechanical Property of WC-TiC-TaC Cemented Carbides

    Institute of Scientific and Technical Information of China (English)

    高姣姣; 姜龙凯; 宋金鹏; 梁国星; 安晶; 谢俊彩; 曹磊; 吕明

    2017-01-01

    本研究采用真空热压烧结技术,在1600℃下制备了WC-TiC-TaC硬质合金材料,研究了TiC含量对其微观组织及力学性能的影响.结果表明,随着TiC含量的增多,硬质合金材料的晶粒显著增大.当TiC的含量从10wt% 增加到25wt%时,硬质合金材料的硬度逐渐增大,最高可达19.81 GPa,这是由于TiC的硬度高于基体WC的硬度;与此同时,硬质合金材料的抗弯强度和断裂韧度逐渐减小.当TiC的含量为10wt%时,材料的抗弯强度有最大值,其值为1147.24 MPa,这是由于在材料内部形成了均匀、细小的晶粒组织;在此含量下,复合材料的增韧机理为细晶增韧、裂纹偏转、裂纹分支、裂纹桥接和韧窝增韧,其断裂韧度有最大值,为14.60 MPa·m1/2.%WC-TiC-TaC cemented carbides were fabricated by hot-pressed sintering at 1600℃. Effects of TiC content on the microstructure and mechanical properties of these cemented carbides were investigated. It was found that when TiC content was increased from 10wt% to 25wt%, both the average grain size and the Vickers hardness increased pro-gressively, but both the flexural strength and the fracture toughness decreased gradually. The increase of Vickers hard-ness was attributed to the increase of TiC content and the hardness of TiC was higher than that of WC. The value of the highest Vickers hardness was 19.81 GPa. This work also showed that the highest flexural strength (1147.24 MPa) was ascribed to the fine and homogeneous grains, and that the highest fracture toughness (14.60 MPa·m1/2) was due to the intensive coupled mechanism of the fine-grain toughening, crack deflection, crack branching, crack bridging, and toughness dimples.

  1. Structural and surface morphological studies of long chain fatty acid thin films deposited by Langmuir-Blodgett technique

    Energy Technology Data Exchange (ETDEWEB)

    Das, Nayan Mani, E-mail: nayanmanidas3@gmail.com [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India); Roy, Dhrubojyoti [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India); Gupta, Mukul [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India); Gupta, P.S. [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India)

    2012-12-15

    In the present work we aim to study the structural and surface morphological characteristics of divalent cation (cadmium ion, Cd{sup 2+}) induced thin mono- to multilayer films of fatty acids such as arachidic acid and stearic acid prepared by the Langmuir-Blodgett (LB) technique. These ultra thin films of various numbers of layers were studied by X-ray diffraction (XRD), X-ray reflectivity (XRR) and Atomic Force Microscopy (AFM). In this specific Y-type deposition, it was found that as the individual layer thickness increases, the corresponding layer by layer interfacial electron density of the thin films decreases. Since the fatty acid chain tries to maintain its minimum value of cross-sectional area, tilting occurs with respect to its nearest neighbor. The tilt angle calculated for 9 layers of cadmium arachidate (CdA{sub 2}) and cadmium stearate (CdSt{sub 2}) are 18 Degree-Sign and 19.5 Degree-Sign , respectively. An asymmetric air gap of thickness {approx}3 A was also seen between the tail parts of 2 molecular chains. The RMS roughness and average height factors calculated through AFM studies show non-uniform surface morphology of both CdA{sub 2} and CdSt{sub 2}, although the calculated topographic variations were found to have more irregularity in case of CdSt{sub 2} than in case of CdA{sub 2}.

  2. Infraordinary Deposits

    DEFF Research Database (Denmark)

    2016-01-01

    The exhibition Infraordinary Deposits presents three works in progress by PhD Fellow Espen Lunde Nielsen from the on-going PhD project Architectural Probes of the Infraordinary: Social Coexistence through Everyday Spaces. The infraordinary is understood as the opposite of the extraordinary...... and as that which is ‘worn half-invisible’ by use. Nevertheless, these unregarded spaces play a vital role to the social dimension of the city. The selected projects (‘urban biopsies’) on display explore how people coexist through these spaces and within the city itself, either through events in real......, daily 8.45 – 15.00 Where: Aarhus School of Architecture, The Canteen, Nørreport 18, 8000 Aarhus C...

  3. Plasma-polymerized perfluoro(methylcyclohexane) coating on ethylene propylene diene elastomer surface: Effect of plasma processing condition on the deposition kinetics, morphology and surface energy of the film

    International Nuclear Information System (INIS)

    Tran, N.D.; Dutta, N.K.; Choudhury, N. Roy

    2005-01-01

    Plasma polymerization of perfluoro (methylcyclohexane) was carried out under cold plasma process operated at 13.56 MHz to deposit pore-free, uniform, ultra-thin film on an ethylene propylene diene terpolymer (EPDM) substrate in a view to modify the surface characteristics. The plasma fluoropolymeric films were formed at different plasma treatment times (from 20 s to 16 min), applied powers (20 to 100 W) and precursor flow rates to produce high quality films in a controllable yet tunable fashion. Scanning electron microscopy was employed successfully to characterize the evolution of the morphological feature in the film and also to determine the thickness of the coating. The surface energy of the film was determined by sessile drop method using different solvents as probe liquids. It is observed that a pore-free homogeneous plasma polymer thin film is formed within 20 s of treatment time, however, the morphology of the film depends on the plasma processing conditions, such as plasma power, precursor flow rate and deposition time. With increased time and power at a constant flow rate, the morphology of the film progressively changes from flat smooth to globular and rough. The kinetics and activation energy of the plasma polymer film deposition process were also estimated. The surface energy of the EPDM substrate decreased dramatically with plasma coating, however, it appears to be independent of the treatment time

  4. Effect of PbI2 deposition rate on two-step PVD/CVD all-vacuum prepared perovskite

    International Nuclear Information System (INIS)

    Ioakeimidis, Apostolos; Christodoulou, Christos; Lux-Steiner, Martha; Fostiropoulos, Konstantinos

    2016-01-01

    In this work we fabricate all-vacuum processed methyl ammonium lead halide perovskite by a sequence of physical vapour deposition of PbI 2 and chemical vapour deposition (CVD) of CH 3 NH 3 I under a static atmosphere. We demonstrate that for higher deposition rate the (001) planes of PbI 2 film show a higher degree of alignment parallel to the sample's surface. From X-ray diffraction data of the resulted perovskite film we derive that the intercalation rate of CH 3 NH 3 I is fostered for PbI 2 films with higher degree of (001) planes alignment. The stoichiometry of the produced perovskite film is also studied by Hard X-ray photoelectron spectroscopy measurements. Complete all-vacuum perovskite solar cells were fabricated on glass/ITO substrates coated by an ultra-thin (5 nm) Zn-phthalocyanine film as hole selective layer. A dependence of residual PbI 2 on the solar cells performance is displayed, while photovoltaic devices with efficiency up to η=11.6% were achieved. - Graphical abstract: A two-step PVD/CVD processed perovskite film with the CVD intercalation rate of CH 3 NCH 3 molecules been fostered by increasing the PVD rate of PbI 2 and prolonging the CVD time. - Highlights: • A simple PVD/CVD process for perovskite film production. • Increased PVD rate yields better alignment of the PbI 2 (001) crystallite planes. • CH 3 NH 3 I intercalation process fostered by increased PbI 2 PVD rate. • Stoichiometric CH 3 NH 3 PbI 3 suitable as absorber in photovoltaic applications • Reduced PbI 2 residue at the bottom of CH 3 NH 3 PbI 3 improves device performance.

  5. Initial deposition and electron paramagnetic resonance defects characterization of TiO{sub 2} films prepared using successive ionic layer adsorption and reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yiyong, E-mail: wuyiyong2001@yahoo.com.cn [National Key Laboratory of Materials Behaviors and Evaluation Technology in Space Environments, Harbin Institute of Technology, P.O. 432, Nan gang District, Harbin, 150080 (China); Shi Yaping [National Key Laboratory of Materials Behaviors and Evaluation Technology in Space Environments, Harbin Institute of Technology, P.O. 432, Nan gang District, Harbin, 150080 (China); Harbin University of Commerce, P.O. 493, Song bei District, Harbin, 150028 (China); Xu Xianbin; Sun Chengyue [National Key Laboratory of Materials Behaviors and Evaluation Technology in Space Environments, Harbin Institute of Technology, P.O. 432, Nan gang District, Harbin, 150080 (China)

    2012-06-01

    Successive ionic layer adsorption and reaction (SILAR) technique was considered promisingly to deposit ultra thin titanium dioxide (TiO{sub 2}) films under ambient condition. In this paper, the growth process, structures and paramagnetic defects of the films were characterized by complementary techniques of atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electron paramagnetic resonance spectroscopy. The results indicate that on glass substrate the SILAR TiO{sub 2} film nucleates in an island mode within the initial five deposition cycles but grows in a layer-by-layer mode afterwards. The growth rate was measured as 4.6 A/cycle. In the as-deposited films, a kind of paramagnetic defects is detected at g (2.0029) and it can be attributed to oxygen vacancies. These as-received oxygen vacancies could be annealed out at 473 K. Ultraviolet irradiation on the as-deposited films can also decrease the density of the defects. The relative mechanisms on the phenomenon were discussed in this paper. - Highlights: Black-Right-Pointing-Pointer TiO{sub 2} films are deposited on glass at 25 Degree-Sign C by successive ionic layer adsorption and reaction method with a rate of 4.6 A/cycle. Black-Right-Pointing-Pointer The films nucleate in an island mode initially but grow in a layer mode afterwards. Black-Right-Pointing-Pointer The SILAR TiO{sub 2} films nucleation period is five cycles. Black-Right-Pointing-Pointer Electron paramagnetic resonance spectroscopy shows that TiO{sub 2} films paramagnetic defects are attributed to oxygen vacancies. Black-Right-Pointing-Pointer They will decrease by anneal or ultraviolet radiation and form hydroxyl or superoxide radicals.

  6. Initial deposition and electron paramagnetic resonance defects characterization of TiO2 films prepared using successive ionic layer adsorption and reaction method

    International Nuclear Information System (INIS)

    Wu Yiyong; Shi Yaping; Xu Xianbin; Sun Chengyue

    2012-01-01

    Successive ionic layer adsorption and reaction (SILAR) technique was considered promisingly to deposit ultra thin titanium dioxide (TiO 2 ) films under ambient condition. In this paper, the growth process, structures and paramagnetic defects of the films were characterized by complementary techniques of atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electron paramagnetic resonance spectroscopy. The results indicate that on glass substrate the SILAR TiO 2 film nucleates in an island mode within the initial five deposition cycles but grows in a layer-by-layer mode afterwards. The growth rate was measured as 4.6 Å/cycle. In the as-deposited films, a kind of paramagnetic defects is detected at g (2.0029) and it can be attributed to oxygen vacancies. These as-received oxygen vacancies could be annealed out at 473 K. Ultraviolet irradiation on the as-deposited films can also decrease the density of the defects. The relative mechanisms on the phenomenon were discussed in this paper. - Highlights: ► TiO 2 films are deposited on glass at 25 °C by successive ionic layer adsorption and reaction method with a rate of 4.6 Å/cycle. ► The films nucleate in an island mode initially but grow in a layer mode afterwards. ► The SILAR TiO 2 films nucleation period is five cycles. ► Electron paramagnetic resonance spectroscopy shows that TiO 2 films paramagnetic defects are attributed to oxygen vacancies. ► They will decrease by anneal or ultraviolet radiation and form hydroxyl or superoxide radicals.

  7. Holocene Tsunami Deposits From Large Tsunamis Along the Kuril Subduction Zone, Northeast Japan

    Science.gov (United States)

    Nanayama, F.; Furukawa, R.; Satake, K.; Soeda, Y.; Shigeno, K.

    2003-12-01

    Holocene tsunami deposits in eastern Hokkaido between Nemuro and Tokachi show that the Kuril subduction zone repeatedly produced earthquakes and tsunamis larger than those recorded in this region since AD 1804 (Nanayama et al., Nature, 424, 660-663, 2003). Twenty-two postulated tsunami sand layers from the past 9500 years are preserved on lake bottom near Kushiro City, and about ten postulated tsunami sand layers from the past 3000 years are preserved in peat layers on the coastal marsh of Kiritappu. We dated these ten tsunami deposits (named Ts1 to Ts10 from shallower to deeper) in peat layers by radiocarbon and tephrochronology, correlated them with historical earthquakes and tsunamis, and surveyed their spatial distribution to estimate the tsunamisO inland inundation limits. Ts10 and Ts9 are under regional tephra Ta-c2 (ca. 2.5 ka) and represent prehistorical events. Ts8 to Ts5 are between two regional tephra layers Ta-c2 and B-Tm (ca. 9th century). In particular, Ts5 is found just below B-Tm, so it is dated 9th century (Heian era). Ts4 is dated ca 13th century (Kamakura era), while Ts3, found just below Us-b and Ta-b (AD 1667-1663), is dated 17th century (Edo era). Ts2 is dated 19th century (Edo era) and may correspond to the AD 1843 Tempo Tokachi-oki earthquake (Mt 8.0) recorded in a historical document Nikkanki of Kokutai-ji temple at Akkeshi. Ts1 is inferred 20th century and may correspond to the tsunami from the AD 1960 Chilean earthquake (M 9.5) or the AD 1952 Tokachi-oki earthquake (Mt 8.2). Our detailed surveys indicate that Ts3 and Ts4 can be traced more than 3 km from the present coast line in Kirittapu marsh, much longer than the limits (< 1 km) of recent deposits Ts1 and Ts2 or documented inundation of the 19th and 20th century tsunamis. The recurrence intervals of great tsunami inundation are about 400 to 500 years, longer than that of typical interplate earthquakes along the Kuril subduction zone. The longer interval and the apparent large tsunami

  8. The Combined Use of Autoradiographic and Electron Microscopic Techniques for Studies on Ultra-Thin Sections of Tritium-Labelled Cells of the Intestinal Epithelium; Emploi Combine de l'Autoradiographie et du Microscope Electronique pour L'Etude de Coupes Ultra-Fines de Cellules Tritiees de l'Epithelium Intestinal; 0421 043e 0432 043c 0435 0414 ; Empleo Combinado de Tecnicas de Autorradiografia y de MicroscopiA Electronica para Estudiar Cortes Ultrafinos de Celulas Tritiadas del Epitelio Intestinal

    Energy Technology Data Exchange (ETDEWEB)

    Hampton, J. C. [Division of Experimental Biology, Baylor University College of Medicine, TX (United States); Quastler, H. [Brookhaven National Laboratory, Upton, Long Island, NY (United States)

    1962-02-15

    The high resolution now obtainable in sectioned cells studied in the electron microscope offers some promise of visualizing some of the intracellular events leading to the synthesis of proteins. The specificity of incorporation of tritiated thymidine into DNA provides a system which can be accurately followed with respect to time and localization within the cell. The work to be reported here demonstrates that it is possible to study ultra-thin sections of labelled cells in the electron microscope, to remove the specimen after suitable electron micrographs have been taken, to apply a coating of emulsion sufficiently thick to obtain an autoradiograph but still thin enough' to permit re-examination of the specimen in the electron microscope and to obtain electron micrographic images of autoradiography of cells previously recorded. The autoradiographic emulsion was applied as follows: a thin film was formed by dipping a small wire loop into liquid emulsion and transferring the film by passing the loop over the mounted specimen which was fixed to the top of a small plastic peg. Adequate control can be achieved by taking a one-half micron section after each ultra-thin section during sectioning, mounting it on a glass slide and applying conventional autoradiographic techniques. Because of the fragile nature of ultra-thin sections, the yield of successful autoradiographs is quite low. In spite of this objection it is expected that with improvements in skill and techniques the method will facilitate a better understanding of vital cell processes. (author) [French] Le haut degre de resolution que l'on peut maintenant obtenir dans l'etude des coupes de cellules au microscope electronique offre quelque possiblite d'observer certains des processus intracellulaires qui menent a la synthese des proteines. Le fait que la thymidine tritiee s'incorpore a l'ADN de facon specifique permet de suivre avec precision le deroulement d'un autre processus dans le temps et leur localisation

  9. Molecular beam deposition of Al2O3 on p-Ge(001)/Ge0.95Sn0.05 heterostructure and impact of a Ge-cap interfacial layer

    International Nuclear Information System (INIS)

    Merckling, C.; Franquet, A.; Vincent, B.; Vandervorst, W.; Loo, R.; Caymax, M.; Sun, X.; Shimura, Y.; Takeuchi, S.; Nakatsuka, O.; Zaima, S.

    2011-01-01

    We investigated the molecular beam deposition of Al 2 O 3 on Ge 0.95 Sn 0.05 surface with and without an ultra thin Ge cap layer in between. We first studied the atomic configuration of both Ge 1-x Sn x and Ge/Ge 1-x Sn x surfaces after deoxidation by reflection high-energy electron diffraction and resulted, respectively, in a c(4x2) and (2x1) surface reconstructions. After in situ deposition of an Al 2 O 3 high-κ gate dielectric we evidenced using time-of-flight secondary ion mass spectroscopy analyses that Sn diffusion was at the origin of high leakage current densities in the Ge 1-x Sn x /Al 2 O 3 gate stack. This damage could be avoided by inserting a thin 5-nm-thick Ge cap between the oxide and the Ge 1-x Sn x layer. Finally, metal-oxide-semiconductor capacitors on the Ge capped sample showed well-behaved capacitance-voltage (C-V) characteristics with interface trap density (D it ) in the range of 10 12 eV -1 cm -2 in mid gap and higher close to the valence band edge.

  10. Economical Atomic Layer Deposition

    Science.gov (United States)

    Wyman, Richard; Davis, Robert; Linford, Matthew

    2010-10-01

    Atomic Layer Deposition is a self limiting deposition process that can produce films at a user specified height. At BYU we have designed a low cost and automated atomic layer deposition system. We have used the system to deposit silicon dioxide at room temperature using silicon tetrachloride and tetramethyl orthosilicate. Basics of atomic layer deposition, the system set up, automation techniques and our system's characterization are discussed.

  11. Ultra-thin Al{sub 2}O{sub 3} coating on the acid-treated 0.3Li{sub 2}MnO{sub 3}⋅0.7LiMn{sub 0.60}Ni{sub 0.25}Co{sub 0.15}O{sub 2} electrode for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Mansoo [Battery Research Center, Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of); Dept. of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Ham, Giyul [Dept. of Materials and Science Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Jin, Bong-Soo; Lee, Sang-Min [Battery Research Center, Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of); Lee, Young Moo [Dept. of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Wang, Guoxiu [Centre for Clean Energy Technology, School of Chemistry and Forensic Science, University of Technology, Sydney, NSW 2007 (Australia); Kim, Hyun-Soo, E-mail: hskim@keri.re.kr [Battery Research Center, Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of)

    2014-09-01

    Highlights: • 0.3Li{sub 2}MnO{sub 3}⋅0.7LiMn{sub 0.60}Ni{sub 0.25}Co{sub 0.15}O{sub 2} composites were preconditioned by HNO{sub 3}. • The alumina thin film was directly coated on the electrode by an atomic layer deposition. • The acid-treated samples showed significantly higher discharge capacity. • The alumina-coated electrode showed the improved capacity retention ratio. - Abstract: The Li and Mn-rich layered composites represented by Li{sub 2}MnO{sub 3}–LiMO{sub 2} has been attracting great interests owing to its exceptional high capacity (⩾250 mA h g{sup −1}) and enhanced structural stability. In order to improve the initial coulombic efficiency and cyclability of the composites, the material has been activated by an acid-treatment and coated with an Al{sub 2}O{sub 3} using an atomic layer deposition (ALD). The acid-treated electrode showed a higher discharge capacity than the as-prepared electrode. The alumina-coated electrode provided an improved specific capacity of the electrode but also cycling stability, when compared with the bare electrode. The electrode coated with the alumina could lead to a decrease in undesirable reactions, thereby acting as a stable protecting layer that could quickly transport Li{sup +} ions during charge and discharge process.

  12. Electro-Deposition Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The electro-deposition laboratory can electro-deposit various coatings onto small test samples and bench level prototypes. This facility provides the foundation for...

  13. Atmospheric Deposition Modeling Results

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset provides data on model results for dry and total deposition of sulfur, nitrogen and base cation species. Components include deposition velocities, dry...

  14. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  15. Preparation and characterization of pulsed laser deposited CdTe thin films at higher FTO substrate temperature and in Ar + O{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Chao; Ming, Zhenxun [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Li, Bing, E-mail: libing70@126.com [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Feng, Lianghuan [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Wu, Judy [Department of Physics and Astronomy, Kansas University, Lawrence 66045 (United States)

    2013-06-20

    Highlights: • CdTe films were deposited by PLD at high substrate temperatures (400 °C, 550 °C). • CdTe films were achieved under the atmosphere (1.2 Torr) of Ar mixed with O{sub 2}. • Deposited CdTe films were cubic phase and had strong (1 0 0) preferred orientation. • Scanning electron microscope (SEM) showed an average grain size of 0.3–0.6 μm. • The ultra-thin film (CdS/PLD-CdTe) solar cell with efficiency of 6.68% was made. -- Abstract: Pulsed laser deposition (PLD) is one of the promising techniques for depositing cadmium telluride (CdTe) thin films. It has been reported that PLD CdTe thin films were almost deposited at the lower substrate temperatures (<300 °C) under vacuum conditions. However, the poor crystallinity of CdTe films prepared in this way renders them not conducive to the preparation of high-efficiency CdTe solar cells. To obtain high-efficiency solar cell devices, better crystallinity and more suitable grain size are needed, which requires the CdTe layer to be deposited by PLD at high substrate temperatures (>400 °C). In this paper, CdTe layers were deposited by PLD (KrF, λ = 248 nm, 10 Hz) at different higher substrate temperatures (T{sub s}). Excellent performance of CdTe films was achieved at higher substrate temperatures (400 °C, 550 °C) under an atmosphere of Ar mixed with O{sub 2} (1.2 Torr). X-ray diffraction analysis confirmed the formation of CdTe cubic phase with a strong (1 0 0) preferential orientation at all substrates temperatures on 60 mJ laser energy. The optical properties of CdTe were investigated, and the band gaps of CdTe films were 1.51 eV and 1.49 eV at substrate temperatures of 400 °C and 550 °C, respectively. Scanning electron microscopy (SEM) showed an average grain size of 0.3–0.6 μm. Thus, under these conditions of the atmosphere of Ar + O{sub 2} (15 Torr) and at the relatively high T{sub s} (500 °C), an thin-film (FTO/PLD-CdS (100 nm)/PLD-CdTe (∼1.5 μm)/HgTe: Cu/Ag) solar cell with an

  16. Acid Deposition Phenomena

    International Nuclear Information System (INIS)

    Ramadan, A.E.K.

    2004-01-01

    Acid deposition, commonly known as acid rain, occurs when emissions from the combustion of fossil fuels and other industrial processes undergo complex chemical reactions in the atmosphere and fall to the earth as wet deposition (rain, snow, cloud, fog) or dry deposition (dry particles, gas). Rain and snow are already naturally acidic, but are only considered problematic when less than a ph of 5.0 The main chemical precursors leading to acidic conditions are atmospheric concentrations of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ). When these two compounds react with water, oxygen, and sunlight in the atmosphere, the result is sulfuric (H 2 SO 4 ) and nitric acids (HNO 3 ), the primary agents of acid deposition which mainly produced from the combustion of fossil fuel and from petroleum refinery. Airborne chemicals can travel long distances from their sources and can therefore affect ecosystems over broad regional scales and in locations far from the sources of emissions. According to the concern of petroleum ministry with the environment and occupational health, in this paper we will discussed the acid deposition phenomena through the following: Types of acidic deposition and its components in the atmosphere Natural and man-made sources of compounds causing the acidic deposition. Chemical reactions causing the acidic deposition phenomenon in the atmosphere. Factors affecting level of acidic deposition in the atmosphere. Impact of acid deposition. Procedures for acidic deposition control in petroleum industry

  17. Deposition Measurements in NSTX

    Science.gov (United States)

    Skinner, C. H.; Kugel, H. W.; Hogan, J. T.; Wampler, W. R.

    2004-11-01

    Two quartz microbalances have been used to record deposition on the National Spherical Torus Experiment. The experimental configuration mimics a typical diagnostic window or mirror. An RS232 link was used to acquire the quartz crystal frequency and the deposited thickness was recorded continuously with 0.01 nm resolution. Nuclear Reaction Analysis of the deposit was consistent with the measurement of the total deposited mass from the change in crystal frequency. We will present measurements of the variation of deposition with plasma conditions. The transport of carbon impurities in NSTX has been modelled with the BBQ code. Preliminary calculations indicated a negligible fraction of carbon generated at the divertor plates in quiescent discharges directly reaches the outer wall, and that transient events are responsible for the deposition.

  18. Shedding of ash deposits

    DEFF Research Database (Denmark)

    Zbogar, Ana; Frandsen, Flemming; Jensen, Peter Arendt

    2009-01-01

    Ash deposits formed during fuel thermal conversion and located on furnace walls and on convective pass tubes, may seriously inhibit the transfer of heat to the working fluid and hence reduce the overall process efficiency. Combustion of biomass causes formation of large quantities of troublesome...... ash deposits which contain significant concentrations of alkali, and earth-alkali metals. The specific composition of biomass deposits give different characteristics as compared to coal ash deposits, i.e. different physical significance of the deposition mechanisms, lower melting temperatures, etc....... Low melting temperatures make straw ashes especially troublesome, since their stickiness is higher at lower temperatures, compared to coal ashes. Increased stickiness will eventually lead to a higher collection efficiency of incoming ash particles, meaning that the deposit may grow even faster...

  19. Uraniferous surficial deposits

    International Nuclear Information System (INIS)

    Toens, P.D.; Hambleton-Jones, B.B.

    1980-10-01

    As a result of the discovery of uranium in surficial deposits of Tertiary to Recent age, in Australia and Southern Africa, increasing attention is being paid to the location and understanding of the genesis of these deposits. The paper discusses the definitions and terminology currently in use and a classification of these deposits is presented. It is concluded that in order to obtain a measure of clarity, the terms calcrete, gypcrete and dolocrete should not be used to describe the uraniferous valley-fill deposits of Southern Africa and Australia [af

  20. Atomic Layer Deposited Thin Films for Dielectrics, Semiconductor Passivation, and Solid Oxide Fuel Cells

    Science.gov (United States)

    Xu, Runshen

    , ultra-thin layer of encapsulating ZnS is coated on the surface of GaSb and GaSb/InAs substrates. The 2 nm-thick ZnS film is found to provide a long-term protection against reoxidation for one order and a half longer times than prior reported passivation likely due to its amorphous structure without pinholes. Finally, a combination of binary ALD processes is developed and demonstrated for the growth of yttria-stabilized zirconia films using alkylamido-cyclopentadiengyls zirconium and tris(isopropyl-cyclopentadienyl)yttrium, as zirconium and yttrium precursors, respectively, with ozone being the oxidant. The desired cubic structure of YSZ films is apparently achieved after post-deposition annealing. Further, platinum is atomic layer deposited as electrode on YSZ (8 mol% of Yttria) within the same system. In order to control the morphology of as-deposited Pt thin structure, the nucleation behavior of Pt on amorphous and cubic YSZ is investigated. Three different morphologies of Pt are observed, including nanoparticle, porous and dense films, which are found to depend on the ALD cycle number and the structure and morphology of they underlying ALD YSZ films.

  1. MAPLE deposition of nanomaterials

    International Nuclear Information System (INIS)

    Caricato, A.P.; Arima, V.; Catalano, M.; Cesaria, M.; Cozzoli, P.D.; Martino, M.; Taurino, A.; Rella, R.; Scarfiello, R.; Tunno, T.; Zacheo, A.

    2014-01-01

    The matrix-assisted pulsed laser evaporation (MAPLE) has been recently exploited for depositing films of nanomaterials by combining the advantages of colloidal inorganic nanoparticles and laser-based techniques. MAPLE-deposition of nanomaterials meeting applicative purposes demands their peculiar properties to be taken into account while planning depositions to guarantee a congruent transfer (in terms of crystal structure and geometric features) and explain the deposition outcome. In particular, since nanofluids can enhance thermal conductivity with respect to conventional fluids, laser-induced heating can induce different ablation thermal regimes as compared to the MAPLE-treatment of soft materials. Moreover, nanoparticles exhibit lower melting temperatures and can experience pre-melting phenomena as compared to their bulk counterparts, which could easily induce shape and or crystal phase modification of the material to be deposited even at very low fluences. In this complex scenario, this review paper focuses on examples of MAPLE-depositions of size and shape controlled nanoparticles for different applications highlights advantages and challenges of the MAPLE-technique. The influence of the deposition parameters on the physical mechanisms which govern the deposition process is discussed.

  2. MAPLE deposition of nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Caricato, A.P., E-mail: annapaola.caricato@le.infn.it [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Arima, V.; Catalano, M. [National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Cesaria, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Cozzoli, P.D. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Martino, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Taurino, A.; Rella, R. [Institute for Microelectronics and Microsystems, IMM-CNR, Via Monteroni, I-73100 Lecce (Italy); Scarfiello, R. [National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Tunno, T. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Zacheo, A. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy)

    2014-05-01

    The matrix-assisted pulsed laser evaporation (MAPLE) has been recently exploited for depositing films of nanomaterials by combining the advantages of colloidal inorganic nanoparticles and laser-based techniques. MAPLE-deposition of nanomaterials meeting applicative purposes demands their peculiar properties to be taken into account while planning depositions to guarantee a congruent transfer (in terms of crystal structure and geometric features) and explain the deposition outcome. In particular, since nanofluids can enhance thermal conductivity with respect to conventional fluids, laser-induced heating can induce different ablation thermal regimes as compared to the MAPLE-treatment of soft materials. Moreover, nanoparticles exhibit lower melting temperatures and can experience pre-melting phenomena as compared to their bulk counterparts, which could easily induce shape and or crystal phase modification of the material to be deposited even at very low fluences. In this complex scenario, this review paper focuses on examples of MAPLE-depositions of size and shape controlled nanoparticles for different applications highlights advantages and challenges of the MAPLE-technique. The influence of the deposition parameters on the physical mechanisms which govern the deposition process is discussed.

  3. A study of TaxC1-x coatings deposited on biomedical 316L stainless steel by radio-frequency magnetron sputtering

    International Nuclear Information System (INIS)

    Ding, M.H.; Wang, B.L.; Li, L.; Zheng, Y.F.

    2010-01-01

    In this paper, Ta x C 1-x coatings were deposited on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at various substrate temperatures (T s ) in order to improve its corrosion resistance and hemocompatibility. XRD results indicated that T s could significantly change the microstructure of Ta x C 1-x coatings. When T s was x C 1-x coatings were in amorphous condition, whereas when T s was ≥150 deg. C, TaC phase was formed, exhibiting in the form of particulates with the crystallite sizes of about 15-25 nm (T s = 300 deg. C). Atomic force microscope (AFM) results showed that with the increase of T s , the root-mean-square (RMS) values of the Ta x C 1-x coatings decreased. The nano-indentation experiments indicated that the Ta x C 1-x coating deposited at 300 deg. C had a higher hardness and modulus. The scratch test results demonstrated that Ta x C 1-x coatings deposited above 150 deg. C exhibited good adhesion performance. Tribology tests results demonstrated that Ta x C 1-x coatings exhibited excellent wear resistance. The results of potentiodynamic polarization showed that the corrosion resistance of the 316L SS was improved significantly because of the deposited Ta x C 1-x coatings. The platelet adhesion test results indicated that the Ta x C 1-x coatings deposited at T s of 150 deg. C and 300 deg. C possessed better hemocompatibility than the coating deposited at T s of 25 deg. C. Additionally, the hemocompatibility of the Ta x C 1-x coating on the 316L SS was found to be influenced by its surface roughness, hydrophilicity and the surface energy.

  4. The role of transparent conducting oxides in metal organic chemical vapour deposition of CdTe/CdS Photovoltaic solar cells

    International Nuclear Information System (INIS)

    Irvine, S.J.C.; Lamb, D.A.; Barrioz, V.; Clayton, A.J.; Brooks, W.S.M.; Rugen-Hankey, S.; Kartopu, G.

    2011-01-01

    A systematic study is made between the relationship of Cd 0.9 Zn 0.1 S/CdTe photovoltaic (PV) device properties for three different commercial transparent conducting oxide (TCO) materials and some experimental CdO to determine the role of the TCO in device performance. The resistance contribution from the TCO was measured after depositing the gold contact architectures directly onto the TCOs. These were compared with the Cd 0.9 Zn 0.1 S/CdTe device properties using the same contact arrangements. Series resistance for the commercial TCOs correlated with their sheet resistance and gave good agreement with the PV device series resistance for the indium tin oxide (ITO) and fluorine doped tin oxide (FTO) 15 Ω/Sq. superstrates. The devices on the thicker FTO 7 Ω/sq superstrates were dominated by a low shunt resistance, which was attributed to the rough surface morphology causing micro-shorts. The device layers on the CdO substrate delaminated but devices were successfully made for ultra-thin CdTe (0.8 μm thick) and compared favourably with the comparable device on ITO. From the measurements on these TCOs it was possible to deduce the back contact resistance and gave an average value of 2 Ω.cm 2 . The correlation of fill factor with series resistance has been compared with the predictions of a 1-D device model and shows excellent agreement. For high efficiency devices the combined series resistance from the TCO and back contact need to be less than 1 Ω.cm 2 .

  5. Urban acid deposition

    Energy Technology Data Exchange (ETDEWEB)

    Conlan, D.E.; Longhurst, J.W.S.; Gee, D.R.; Hare, S.E.

    1991-07-01

    In this document results from the Greater Manchester Acid Deposition Survey (GMADS), an urban precipitation chemistry network, for 1990 are presented. Full analytical methods are described along with the precision and accuracy of the methods used. The spatial variability of precipitation chemistry and deposition over this urban region was investigated using a network of twenty collectors. Concentrations of non marine sulphate, ammonium, calcium and hydrogen, and nitrogen dioxide gas concentrations all show significant spatial variability. The spatial variability of the deposition rates of non marine sulphate, nitrate, ammonium, hydrogen and calcium were significant. (Author).

  6. Electroless atomic layer deposition

    Science.gov (United States)

    Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

    2017-10-31

    A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.

  7. Chemical vapor deposition of tantalum on graphite cloth for making hot pressed fiber reinforced carbide-graphite composite

    International Nuclear Information System (INIS)

    Hollabaugh, C.M.; Davidson, K.V.; Radosevich, C.L.; Riley, R.E.; Wallace, T.C.

    1977-01-01

    Conditions for the CVD of a uniform coating of Ta on fibers of a woven graphite cloth were established. The effect of gas composition, pressure, and temperature were investigated, and the conditions that gave the desired results are presented. Several layers of the coated cloth were hot pressed to produce a TaC--C composite having uniformly dispersed, fine-grained TaC in graphite. Three compositions were hot pressed: 15, 25, and 40 volume percent carbide. 8 figures, 2 tables

  8. Alluvial Deposits in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This coverage maps alluvial deposits throughout Iowa. This generally would include areas of alluvial soils associated with modern streams that are identified on...

  9. 75 FR 20041 - Deposits

    Science.gov (United States)

    2010-04-16

    ... transmission to (202) 906- 6518; or send an e-mail to [email protected] . OTS will post... DD implements the Truth in Savings Act, part of the Federal Deposit Insurance Corporation Improvement...

  10. Modeled Wet Nitrate Deposition

    Data.gov (United States)

    U.S. Environmental Protection Agency — Modeled data on nitrate wet deposition was obtained from Dr. Jeff Grimm at Penn State Univ. Nitrate wet depostion causes acidification and eutrophication of surface...

  11. Uranium deposit research, 1983

    International Nuclear Information System (INIS)

    Ruzicka, V.; LeCheminant, G.M.

    1984-01-01

    Research on uranium deposits in Canada, conducted as a prerequisite for assessment of the Estimated Additional Resources of uranium, revealed that (a) the uranium-gold association in rudites of the Huronian Supergroup preferably occurs in the carbon layers; (b) chloritized ore at the Panel mine, Elliot Lake, Ontario, occurs locally in tectonically disturbed areas in the vicinity of diabase dykes; (c) mineralization in the Black Sturgeon Lake area, Ontario, formed from solutions in structural and lithological traps; (d) the Cigar Lake deposit, Saskatchewan, has two phases of mineralization: monomineralic and polymetallic; (e) mineralization of the JEB (Canoxy Ltd.) deposit is similar to that at McClean Lake; (f) the uranium-carbon assemblage was identified in the Claude deposit, Carswell Structure; and (g) the Otish Mountains area, Quebec, should be considered as a significant uranium-polymetallic metallogenic province

  12. Automatic Payroll Deposit System.

    Science.gov (United States)

    Davidson, D. B.

    1979-01-01

    The Automatic Payroll Deposit System in Yakima, Washington's Public School District No. 7, directly transmits each employee's salary amount for each pay period to a bank or other financial institution. (Author/MLF)

  13. Deposition of acidifying compounds

    International Nuclear Information System (INIS)

    Fowler, D.; Cape, J.N.; Sutton, M.A.; Mourne, R.; Hargreaves, K.J.; Duyzer, J.H.; Gallagher, M.W.

    1992-01-01

    Inputs of acidifying compounds to terrestrial ecosystems include deposition of the gases NO 2 , NO, HNO 2 , HNO 3 , NH 3 and SO 2 and the ions NO 3- , NH 4+ , SO 4 2- and H + in precipitation, cloud droplets and particles. Recent research has identified particular ecosystems and regions in which terrestrial effects are closely linked with specific deposition processes. This review paper identifies areas in which important developments have occurred during the last five years and attempts to show which aspects of the subject are most important for policy makers. Amongst the conclusions drawn, the authors advise that current uncertainties in estimates of S and N inputs by dry deposition should be incorporated in critical load calculations, and that, in regions dominated by wet deposition, spatial resolution of total inputs should be improved to match the current scales of information on landscape sensitivity to acidic inputs. 44 refs., 9 figs

  14. Speleothem (Cave Deposit) Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, and other aspects of climate derived from mineral deposits found in caves. Parameter keywords describe what was measured...

  15. Ferroelectrics onto silicon prepared by chemical solution deposition methods: from the thin film to the self-assembled systems

    Directory of Open Access Journals (Sweden)

    Calzada, M. L.

    2006-06-01

    Full Text Available The work of the authors during the last years on ferroelectric thin and ultra-thin films deposited by Chemical Solution Deposition (CSD onto silicon based substrates is reviewed in this paper. Ferroelectric layers integrated with silicon substrates have potential use in the new micro/nanoelectronic devices. Two hot issues are here considered: 1 the use of low processing temperatures of the ferroelectric film, with the objective of not producing any damage on the different elements of the device heterostructure, and 2 the downscaling of the ferroelectric material with the aim of achieving the high densities of integration required in the next generation of nanoelectronic devices. The UV-assisted Rapid Thermal Processing has successfully been used in our laboratory for the fabrication of ferroelectric films at low temperatures. Preliminary results on the CSD preparation of nanosized ferroelectric structures are shown.

    Este artículo revisa el trabajo realizado por los autores durante los últimos años sobre lámina delgada y ultra-delgada ferroeléctrica preparada mediante el depósito químico de disoluciones (CSD sobre substratos de silicio. Las películas ferroeléctricas integradas con silicio tienen potenciales usos en los nuevos dispositivos micro/nanoelectrónicos. Dos aspectos claves son aquí considerados: 1 el uso de bajas temperaturas de procesado de la lámina ferroeléctrica, con el fin de no dañar los diferentes elementos que forman la heteroestructura del dispositivo y 2 la disminución de tamaño del material ferroeléctrico con el fin de conseguir las altas densidades de integración requeridas en la próxima generación de dispositivos nanoelectróncos. Los procesos térmicos rápidos asistidos con irradiación UV se están usando en nuestro laboratorio para conseguir la fabricación del material ferroeléctrico a temperaturas bajas compatibles con la tecnología del silicio. Se muestran resultados preliminares sobre

  16. Gemstone deposits of Serbia

    Directory of Open Access Journals (Sweden)

    Miladinović Zoran

    2016-06-01

    Full Text Available Gemstone minerals in Serbia have never been regarded as an interesting and significant resource. Nevertheless, more than 150 deposits and occurrences have been recorded and some of them preliminarily explored in the last 50 years. The majority of deposits and occurrences are located within the Serbo-Macedonian metallogenic province and the most significant metallogenic units at the existing level of knowledge are the Fruska Gora ore district, Cer ore district, Sumadija metallogenic zone, Kopaonik metallogenic zone and Lece-Halkidiki metallogenic zone. The most important genetic type of deposits is hydrothermal, particularly in case of serpentinite/peridotite as host/parent rock. Placer deposits are also economically important. The dominant gemstones are silica minerals: chalcedony (Chrysoprase, carnelian, bluish chalcedony etc., jasper (picture, landscape, red etc., common opal (dendritic, green, milky white etc., silica masses (undivided, and quartz (rock crystal, amethyst etc.. Beside silica minerals significant gemstones in Serbia include also beryl (aquamarine, garnet (almandine and pyrope, tourmaline, fluorite, rhodochrosite, carbonate-silica breccia, carbonate-silica onyx, silicified wood, howlite, serpentinite, marble onyx, and kyanite. This paper aims to present an overview of Serbian gemstone deposits and occurrences and their position based on a simplified gemstone metallogenic map of Serbia, as well as genetic-industrial classification of gemstone deposits and gemstone varieties.

  17. Uranium deposits in Africa

    International Nuclear Information System (INIS)

    Wilpolt, R.H.; Simov, S.D.

    1979-01-01

    Africa is not only known for its spectacular diamond, gold, copper, chromium, platinum and phosphorus deposits but also for its uranium deposits. At least two uranium provinces can be distinguished - the southern, with the equatorial sub-province; and the south Saharan province. Uranium deposits are distributed either in cratons or in mobile belts, the first of sandstone and quartz-pebble conglomerate type, while those located in mobile belts are predominantly of vein and similar (disseminated) type. Uranium deposits occur within Precambrian rocks or in younger platform sediments, but close to the exposed Precambrian basement. The Proterozoic host rocks consist of sediments, metamorphics or granitoids. In contrast to Phanerozoic continental uranium-bearing sediments, those in the Precambrian are in marginal marine facies but they do contain organic material. The geology of Africa is briefly reviewed with the emphasis on those features which might control the distribution of uranium. The evolution of the African Platform is considered as a progressive reduction of its craton area which has been affected by three major Precambrian tectonic events. A short survey on the geology of known uranium deposits is made. However, some deposits and occurrences for which little published material is available are treated in more detail. (author)

  18. Gemstone deposits of Serbia

    Science.gov (United States)

    Miladinović, Zoran; Simić, Vladimir; Jelenković, Rade; Ilić, Miloje

    2016-06-01

    Gemstone minerals in Serbia have never been regarded as an interesting and significant resource. Nevertheless, more than 150 deposits and occurrences have been recorded and some of them preliminarily explored in the last 50 years. The majority of deposits and occurrences are located within the Serbo-Macedonian metallogenic province and the most significant metallogenic units at the existing level of knowledge are the Fruska Gora ore district, Cer ore district, Sumadija metallogenic zone, Kopaonik metallogenic zone and Lece-Halkidiki metallogenic zone. The most important genetic type of deposits is hydrothermal, particularly in case of serpentinite/peridotite as host/parent rock. Placer deposits are also economically important. The dominant gemstones are silica minerals: chalcedony (Chrysoprase, carnelian, bluish chalcedony etc.), jasper (picture, landscape, red etc.), common opal (dendritic, green, milky white etc.), silica masses (undivided), and quartz (rock crystal, amethyst etc.). Beside silica minerals significant gemstones in Serbia include also beryl (aquamarine), garnet (almandine and pyrope), tourmaline, fluorite, rhodochrosite, carbonate-silica breccia, carbonate-silica onyx, silicified wood, howlite, serpentinite, marble onyx, and kyanite. This paper aims to present an overview of Serbian gemstone deposits and occurrences and their position based on a simplified gemstone metallogenic map of Serbia, as well as genetic-industrial classification of gemstone deposits and gemstone varieties.

  19. Effect of composition on the matrix transformation of the Co-Re-Cr-Ta-C alloys

    Czech Academy of Sciences Publication Activity Database

    Beran, Přemysl; Mukherji, D.; Strunz, Pavel; Gilles, R.; Hofmann, M.; Karge, L.; Dolotko, O.; Rösler, J.

    2016-01-01

    Roč. 22, č. 4 (2016), s. 562-571 ISSN 1598-9623 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389005 Keywords : alloys * phase transformation * scanning electron microscopy (SEM) * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.889, year: 2016

  20. Vein type uranium deposits

    International Nuclear Information System (INIS)

    1986-01-01

    Veins are tabular- or sheet-like masses of minerals occupying or following a fracture or a set of fractures in the enclosing rock. They have been formed later than the country rock and fractures, either by filling of the open spaces or by partial or complete replacement of the adjoining rock or most commonly by both of these processes combined. This volume begins with the occurrences and deposits known from old shield areas and the sedimentary belts surrounding them. They are followed by papers describing the European deposits mostly of Variscan age, and by similar deposits known from China being of Jurassic age. The volume is completed by two papers which do not fit exactly in the given scheme. A separate abstract was prepared for each of the 25 papers in this report

  1. Provisional results from accelerated testing of ultra thin-layer reinforced concrete in South Africa

    CSIR Research Space (South Africa)

    Du Plessis, L

    2009-08-01

    Full Text Available The CSIR Built-Environment, in conjunction with the University of Pretoria and the Cement and Concrete Institute of South Africa, developed a low cost option for the upgrading of unsurfaced (gravel) roads. The proposed solution is the placing of a...

  2. Robust ultra-thin RuMo alloy film as a seedless Cu diffusion barrier

    International Nuclear Information System (INIS)

    Hsu, Kuo-Chung; Perng, Dung-Ching; Wang, Yi-Chun

    2012-01-01

    Highlights: ► A 5 nm-thick Mo added Ru film has been investigated as a Cu diffusion barrier layer. ► RuMo film provides over 175 °C improvement in thermal stability than that of pure Ru layer. ► The 5 nm-thick RuMo film shows excellent barrier performance against Cu diffusion upon 725 °C. - Abstract: This study investigated the properties of 5 nm-thick RuMo film as a Cu diffusion barrier. The sheet resistance variation and X-ray diffraction patterns show that the RuMo alloy film has excellent barrier performance and that it is stable upon annealing at 725 °C against Cu. The transmission electron microscopy micrograph and diffraction patterns show that the RuMo film is an amorphous-like structure, whereas pure Ru film is a nano-crystalline structure. The elements’ depth profiles, analyzed by X-ray photoelectron spectroscopy, indicate no inter-diffusion behavior between the Cu and Si layer, even annealing at 700 °C. Lower leakage current has been achieved from the Cu/barrier/insulator/Si test structure using RuMo film as the barrier layer. A 5 nm ultrathin RuMo film provided two orders of magnitude improvement in leakage current and also exhibited a 175 °C improvement in thermal stability than that of the pure Ru film. It is a potential candidate as a seedless Cu diffusion barrier for advanced Cu interconnects.

  3. Radiation induced leakage current and stress induced leakage current in ultra-thin gate oxides

    International Nuclear Information System (INIS)

    Ceschia, M.; Paccagnella, A.; Cester, A.; Scarpa, A.

    1998-01-01

    Low-field leakage current has been measured in thin oxides after exposure to ionizing radiation. This Radiation Induced Leakage Current (RILC) can be described as an inelastic tunneling process mediated by neutral traps in the oxide, with an energy loss of about 1 eV. The neutral trap distribution is influenced by the oxide field applied during irradiation, thus indicating that the precursors of the neutral defects are charged, likely being defects associated to trapped holes. The maximum leakage current is found under zero-field condition during irradiation, and it rapidly decreases as the field is enhanced, due to a displacement of the defect distribution across the oxide towards the cathodic interface. The RILC kinetics are linear with the cumulative dose, in contrast with the power law found on electrically stressed devices

  4. An ultra-thin Schottky diode as a transmission particle detector for biological microbeams

    Science.gov (United States)

    Harken, Andrew; Randers-Pehrson, Gerhard; Attinger, Daniel; Brenner, David J.

    2013-01-01

    We fabricated ultrathin metal-semiconductor Schottky diodes for use as transmission particle detectors in the biological microbeam at Columbia University’s Radiological Research Accelerator Facility (RARAF). The RARAF microbeam can deliver a precise dose of ionizing radiation in cell nuclei with sub-micron precision. To ensure an accurate delivery of charged particles, the facility currently uses a commercial charged-particle detector placed after the sample. We present here a transmission detector that will be placed between the particle accelerator and the biological specimen, allowing the irradiation of samples that would otherwise block radiation from reaching a detector behind the sample. Four detectors were fabricated with co-planar gold and aluminum electrodes thermally evaporated onto etched n-type crystalline silicon substrates, with device thicknesses ranging from 8.5 μm – 13.5 μm. We show coincident detections and pulse-height distributions of charged particles in both the transmission detector and the commercial detector above it. Detections are demonstrated at a range of operating conditions, including incoming particle type, count rate, and beam location on the detectors. The 13.5 μm detector is shown to work best to detect 2.7 MeV protons (H+), and the 8.5 μm detector is shown to work best to detect 5.4 MeV alpha particles (4He++). The development of a transmission detector enables a range of new experiments to take place at RARAF on radiation-stopping samples such as thick tissues, targets that need immersion microscopy, and integrated microfluidic devices for handling larger quantities of cells and small organisms. PMID:24058378

  5. Extrinsic versus intrinsic ferroelectric switching: experimental investigations using ultra-thin PVDF Langmuir-Blodgett films

    International Nuclear Information System (INIS)

    Kliem, H; Tadros-Morgane, R

    2005-01-01

    Mechanisms of extrinsic and intrinsic switching phenomena in ferroelectrics are explained and existing models are summarized. Then, criteria for an experimental distinction between both models are elaborated. Samples with thicknesses ranging from 2.7 to 63.8 nm prepared by a Langmuir-Blodgett technique were investigated with respect to these criteria. Measurements of their polarization switching behaviour, their polarization hysteresis loops, and their coercive fields were carried out. It is found that the coercive fields increase with decreasing sample thickness. Also, the switching time increases with decreasing sample thickness and it increases with decreasing field strength. The switching process turns out to be thermally activated. We find that neither intrinsic nor extrinsic models are sufficient to describe the experimental situation

  6. First-Principles Study of Superconductivity in Ultra- thin Pb Films

    Science.gov (United States)

    Noffsinger, Jesse; Cohen, Marvin L.

    2010-03-01

    Recently, superconductivity in ultrathin layered Pb has been confirmed in samples with as few as two atomic layers [S. Qin, J. Kim, Q. Niu, and C.-K. Shih, Science 2009]. Interestingly, the prototypical strong-coupling superconductor exhibits different Tc's for differing surface reconstructions in samples with only two monolayers. Additionally, Tc is seen to oscillate as the number of atomic layers is increased. Using first principles techniques based on Wannier functions, we analyze the electronic structure, lattice dynamics and electron-phonon coupling for varying thicknesses and surface reconstructions of layered Pb. We discuss results as they relate to superconductivity in the bulk, for which accurate calculations of superconducting properties can be compared to experiment [W. L. McMillan and J.M. Rowell, PRL 1965]. This work was supported by National Science Foundation Grant No. DMR07-05941, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by the Lawrencium computational cluster resource provided by the IT Division at the Lawrence Berkeley National Laboratory (Supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231)

  7. Reliability study of ultra-thin gate oxides on strained-Si/SiGe MOS structures

    International Nuclear Information System (INIS)

    Varzgar, John B.; Kanoun, Mehdi; Uppal, Suresh; Chattopadhyay, Sanatan; Tsang, Yuk Lun; Escobedo-Cousins, Enrique; Olsen, Sarah H.; O'Neill, Anthony; Hellstroem, Per-Erik; Edholm, Jonas; Ostling, Mikael; Lyutovich, Klara; Oehme, Michael; Kasper, Erich

    2006-01-01

    The reliability of gate oxides on bulk Si and strained Si (s-Si) has been evaluated using constant voltage stressing (CVS) to investigate their breakdown characteristics. The s-Si architectures exhibit a shorter life time compared to that of bulk Si, which is attributed to higher bulk oxide charges (Q ox ) and increased surface roughness in the s-Si structures. The gate oxide in the s-Si structure exhibits a hard breakdown (HBD) at 1.9 x 10 4 s, whereas HBD is not observed in bulk Si up to a measurement period of 1.44 x 10 5 s. The shorter lifetime of the s-Si gate oxide is attributed to a larger injected charge (Q inj ) compared to Q inj in bulk Si. Current-voltage (I-V) measurements for bulk Si samples at different stress intervals show an increase in stress induced leakage current (SILC) of two orders in the low voltage regime from zero stress time to up to 5 x 10 4 s. In contrast, superior performance enhancements in terms of drain current, maximum transconductance and effective channel mobility are observed in s-Si MOSFET devices compared to bulk Si. The results from this study indicate that further improvement in gate oxide reliability is needed to exploit the sustained performance enhancement of s-Si devices over bulk Si

  8. Confinement induced ordering in dewetting of ultra-thin polymer bilayers on nanopatterned substrates.

    Science.gov (United States)

    Bhandaru, Nandini; Das, Anuja; Mukherjee, Rabibrata

    2016-01-14

    We report the dewetting of a thin bilayer of polystyrene (PS) and poly(methylmethacrylate) (PMMA) on a topographically patterned nonwettable substrate comprising an array of pillars, arranged in a square lattice. With a gradual increase in the concentration of the PMMA solution (Cn-PMMA), the morphology of the bottom layer changes to: (1) an aligned array of spin dewetted droplets arranged along substrate grooves at very low Cn-PMMA; (2) an interconnected network of threads surrounding each pillar at intermediate Cn-PMMA; and (3) a continuous bottom layer at higher Cn-PMMA. On the other hand the morphology of the PS top layer depends largely on the nature of the pre-existing bottom layer, in addition to Cn-PS. An ordered array of PMMA core-PS shell droplets forms right after spin coating when both Cn-PMMA and Cn-PS are very low. Bilayers with all other initial configurations evolve during thermal annealing, resulting in a variety of ordered structures. Unique morphologies realized include laterally coexisting structures of the two polymers confined within the substrate grooves due to initial rupture of the bottom layer on the substrate followed by a squeezing flow of the top layer; an array of core-shell and single polymer droplets arranged in an alternating order etc., to highlight a few. Such structures cannot be fabricated by any stand-alone lithography technique. On the other hand, in some cases the partially dewetted bottom layer imparts stability to an intact top PS layer against dewetting. Apart from ordering, under certain specific conditions significant miniaturization and downsizing of dewetted feature periodicity and dimension as compared to dewetting of a single layer on a flat substrate is observed. With the help of a morphology phase diagram we show that ordering is achieved over a wide combination of Cn-PMMA and Cn-PS, though the morphology and dewetting pathway differs significantly with variation in the thickness of the individual layers.

  9. Ultra-thin MoS{sub 2} irradiated with highly charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Hopster, J.; Kozubek, R.; Krämer, J.; Sokolovsky, V.; Schleberger, M., E-mail: marika.schleberger@uni-due.de

    2013-12-15

    Single MoS{sub 2} layers exfoliated on KBr have been irradiated with highly charged Xe ions, i.e. with Xe{sup 35+} and Xe{sup 40+}. By atomic force microscopy (AFM) we identified pits and hillocks induced by single ion impacts. The latter ones appear on single layer and bulk-like MoS{sub 2} after both irradiations, whereas their diameter and height apparently depend on the charge state q and layer number. By comparison of contact mode and tapping mode AFM measurements we deduce that these ion induced defects are topographical hillocks accompanied by an enhanced friction. In contrast to this, pit-like structures were only observed on single layer MoS{sub 2} irradiated with q = 40. Taking into account the well known ion induced pit formation on KBr due to defect mediated sputtering, we deduce that pit formation takes place in the substrate and not in the MoS{sub 2} layer.

  10. Optical properties of self assembled oriented island evolution of ultra-thin gold layers

    International Nuclear Information System (INIS)

    Worsch, Christian; Kracker, Michael; Wisniewski, Wolfgang; Rüssel, Christian

    2012-01-01

    Gold layers with a thickness of only 8 to 21 nm were sputtered on soda–lime–silica glasses. Subsequent annealing at 300 and 400 °C for 1 and 24 h resulted in the formation of separated round gold particles with diameters from 8 to 200 nm. Crystal orientations were described using X-ray diffraction and electron backscatter diffraction. The gold particles are oriented with their (111) planes perpendicular to the surface. Most gold nano particles are single crystalline, some particles are twinned. Thermal annealing of sputtered gold layers resulted in purple samples with a coloration comparable to that of gold ruby glasses. The color can be controlled by the thickness of the sputtered gold layer and the annealing conditions. The simple method of gold film preparation and the annealing temperature dependent properties of the layers make them appropriate for practical applications. - Highlights: ► We produce gold nano particle layers on amorphous substrates. ► Thin sputtered gold layers were annealed at low temperatures. ► Various colors can be achieved reproducibly and UV–vis-NIR spectra are reported. ► A 111-texture of the particles is described as well as twinning. ► The process is suitable for mass production.

  11. In situ X-ray synchrotron study of organic semiconductor ultra-thin films growth

    International Nuclear Information System (INIS)

    Moulin, J.-F.; Dinelli, F.; Massi, M.; Albonetti, C.; Kshirsagar, R.; Biscarini, F.

    2006-01-01

    In this work we present an X-ray diffraction study of the early stages of growth of an organic semiconductor (sexithiophene, T 6 ) thin film prepared by high vacuum sublimation. Specular reflectometry and grazing incidence X-ray diffraction were used to monitor the formation of T 6 films on silicon oxide. Our results show that T 6 grows as a crystalline layer from the beginning of the evaporation. The reflectometry analysis suggests that, in the range of rates and temperatures studied, the growth is never layer by layer but rather 3D in nature. In-plane GIXD has allowed us to observe for the first time a thin film phase of T 6 formed of molecules standing normal to the substrate and arranged in a compressed unit cell with respect to the bulk, i.e. the unit cell parameters b and c are relatively smaller. We have followed the dynamics of formation of this new phase and identified the threshold of appearance of the bulk phase, which occurs above ∼5-6 monolayers. These results are relevant to the problem of organic thin film transistors, for which we have previously demonstrated experimentally that only the first two monolayers of T 6 films are involved in the electrical transport. The layers above the second one do not effectively contribute to charge mobility, either because they are more 'disordered' or because of a screening of the gate field

  12. Writing on ultra thin uniaxially oriented polymer films with an electron beam

    International Nuclear Information System (INIS)

    Petermann, J.; Wenderoth, K.

    1990-01-01

    Information storage polymers have been described and used for many years. When using an electron beam to store information, chemical changes in the macromolecules via local radiation damage is utilized to print the information into the polymer. This letter reports the writing of optically detectable information into birefringent polymer films. The method is based on the fact that preferred orientation of the macromolecules can be destroyed by electron radiation damage. The damage is produced by an electron beam in a transmission electron microscope. The resulting information is observed optically in a polarizing microscope. The polymer films used in the present study were polybutene 1 (PB 1), polyethylene (PE) and polyvinyl-idenfluoride (PVDF). (author)

  13. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    International Nuclear Information System (INIS)

    Yang, Nam Chul; Lee, Jaeho; Song, Myung-Won; Ahn, Nari; Kim, Mu-Hyun; Lee, Songtaek; Chin, Byung Doo

    2007-01-01

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad(TM) of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O 3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process

  14. Lipids of the ultra-thin square halophilic archaeon Haloquadratum walsbyi

    Directory of Open Access Journals (Sweden)

    Simona LoBasso

    2008-01-01

    Full Text Available The lipid composition of the extremely halophilic archaeon Haloquadratum walsbyi was investigated by thin-layer chromatography and electrospray ionization-mass spectrometry. The analysis of neutral lipids showed the presence of vitamin MK-8, squalene, carotene, bacterioruberin and several retinal isomers. The major polar lipids were phosphatidylglycerophosphate methyl ester, phosphatidylglycerosulfate, phosphatidylglycerol and sulfated diglycosyl diether lipid. Among cardiolipins, the tetra-phytanyl or dimeric phospholipids, only traces of bisphosphatidylglycerol were detected. When the cells were exposed to hypotonic medium, no changes in the membrane lipid composition occurred. Distinguishing it from other extreme halophiles of the Halobacteriaceae family, the osmotic stress did not induce the neo-synthesis of cardiolipins in H. walsbyi. The difference may depend on the three-laminar structure of the cell wall, which differs significantly from that of other Haloarchaea.

  15. Ultra thin buried oxide layers formed by low dose Simox process

    Energy Technology Data Exchange (ETDEWEB)

    Aspar, B.; Pudda, C.; Papon, A.M. [CEA Centre d`Etudes de Grenoble, 38 (France). Lab. d`Electronique et d`Instrumentation; Auberton Herve, A.J.; Lamure, J.M. [SOITEC, 38 - Grenoble (France)

    1994-12-31

    Oxygen low dose implantation is studied for two implantation energies. For 190 keV, a continuous buried oxide layer is obtained with a high dislocation density in the top silicon layer due to SiO{sub 2} precipitates. For 120 keV, this silicon layer is free of SiO{sub 2} precipitate and has a low dislocation density. Low density of pin-holes is observed in the buried oxide. The influence of silicon islands in the buried oxide on the breakdown electric fields is discussed. (authors). 6 refs., 5 figs.

  16. An ultra-thin Schottky diode as a transmission particle detector for biological microbeams

    International Nuclear Information System (INIS)

    Grad, M; Harken, A; Randers-Pehrson, G; Brenner, D J; Attinger, D

    2012-01-01

    We fabricated ultrathin metal-semiconductor Schottky diodes for use as transmission particle detectors in the biological microbeam at Columbia University's Radiological Research Accelerator Facility (RARAF). The RARAF microbeam can deliver a precise dose of ionizing radiation in cell nuclei with sub-micron precision. To ensure an accurate delivery of charged particles, the facility currently uses a commercial charged-particle detector placed after the sample. We present here a transmission detector that will be placed between the particle accelerator and the biological specimen, allowing the irradiation of samples that would otherwise block radiation from reaching a detector behind the sample. Four detectors were fabricated with co-planar gold and aluminum electrodes thermally evaporated onto etched n-type crystalline silicon substrates, with device thicknesses ranging from 8.5 μm - 13.5 μm. We show coincident detections and pulse-height distributions of charged particles in both the transmission detector and the commercial detector above it. Detections are demonstrated at a range of operating conditions, including incoming particle type, count rate, and beam location on the detectors. The 13.5 μm detector is shown to work best to detect 2.7 MeV protons (H + ), and the 8.5 μm detector is shown to work best to detect 5.4 MeV alpha particles ( 4 He ++ ). The development of a transmission detector enables a range of new experiments to take place at RARAF on radiation-stopping samples such as thick tissues, targets that need immersion microscopy, and integrated microfluidic devices for handling larger quantities of cells and small organisms.

  17. Engineering of an ultra-thin molecular superconductor by charge transfer

    Science.gov (United States)

    Hla, Saw Wai; Hassanien, Abdelrahim; Kendal, Clark

    2016-06-07

    A method of forming a superconductive device of a single layer of (BETS).sub.2GaCl.sub.4 molecules on a substrate surface which displays a superconducting gap that increases exponentially with the length of the molecular chain is provided.

  18. Oxygen-enabled control of Dzyaloshinskii-Moriya Interaction in ultra-thin magnetic films

    KAUST Repository

    Belabbes, Abderrezak; Bihlmayer, Gustav; Blü gel, Stefan; Manchon, Aurelien

    2016-01-01

    ferromagnets, resulting in spin spirals and nanoskyrmion lattices. Here, using relativistic first-principles calculations, we demonstrate that the magnitude and sign of DMI can be entirely controlled by tuning the oxygen coverage of the magnetic film, therefore

  19. Ultra-thin reinforced concrete pavements (UTRCP): Addressing the design issues

    CSIR Research Space (South Africa)

    Du Plessis, L

    2014-07-01

    Full Text Available . This paper deals with an analytical evaluation based on laboratory results and computer modeling to determine the stress condition under loading and to determine the design life of the UTRCP pavement system under various loading states. The paper includes a...

  20. Ultra-thin layer chromatography with integrated silver colloid-based SERS detection.

    Science.gov (United States)

    Wallace, Ryan A; Lavrik, Nickolay V; Sepaniak, Michael J

    2017-01-01

    Simplified lab-on-a-chip techniques are desirable for quick and efficient detection of analytes of interest in the field. The following work involves the use of deterministic pillar arrays on the micro-scale as a platform to separate compounds, and the use of Ag colloid within the arrays as a source of increased signal via surface enhanced Raman spectroscopy (SERS). One problem traditionally seen with SERS surfaces containing Ag colloid is oxidation; however, our platforms are superhydrophobic, reducing the amount of oxidation taking place on the surface of the Ag colloid. This work includes the successful separation and SERS detection of a fluorescent dye compounds (resorufin and sulforhodamine 640), fluorescent anti-tumor drugs (Adriamycin and Daunomycin), and purine and pyrimidine bases (adenine, cytosine, guanine, hypoxanthine, and thymine). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Degradation of ultra-thin gate oxide LDD NMOSFET under GIDL stress

    International Nuclear Information System (INIS)

    Hu Shigang; Hao Yue; Cao Yanrong; Ma Xiaohua; Wu Xiaofeng; Chen Chi; Zhou Qingjun

    2009-01-01

    The degradation of device under GIDL (gate-induced drain leakage current) stress has been studied using LDD NMOSFETs with 1.4 nm gate oxides. Experimental result shows that the degradation of device parameters depends more strongly on V d than on V g . The characteristics of the GIDL current are used to analyze the damage generated during the stress. It is clearly found that the change of GIDL current before and after stress can be divided into two stages. The trapping of holes in the oxide is dominant in the first stage, but that of electrons in the oxide is dominant in the second stage. It is due to the common effects of edge direct tunneling and band-to-band tunneling. SILC (stress induced leakage current) in the NMOSFET decreases with increasing stress time under GIDL stress. The degradation characteristic of SILC also shows saturating time dependence. SILC is strongly dependent on the measured gate voltage. The higher the measured gate voltage, the less serious the degradation of the gate current. A likely mechanism is presented to explain the origin of SILC during GIDL stress.

  2. An ultra-thin miniature loop heat pipe cooler for mobile electronics

    International Nuclear Information System (INIS)

    Zhou, Guohui; Li, Ji; Lv, Lucang

    2016-01-01

    Highlights: • A 1.2 mm thick miniature loop heat pipe was developed. • The mLHP can manage a wide range of heat loads at natural convection. • A minimum mLHP thermal resistance of 0.111 °C/W was achieved at 11 W. • The proposed mLHP is a promising solution for cooling mobile electronics. - Abstract: In this paper, we present a miniature loop heat pipe (mLHP) employing a 1.2 mm thick flat evaporator and a vapor line, liquid line and condenser with a 1.0 mm thickness. The mLHP employs an internal wick structure fabricated of sintered fine copper mesh, comprised of a primary wick structure in the evaporator to provide the driving force for circulating the working fluid, and a secondary wick inside the liquid line to promote the flow of condensed working fluid back to the evaporator. All tests were conducted under air natural convection at an ambient temperature of 24 ± 1 °C. The proposed mLHP demonstrated stable start-up behavior at a low heat load of 2 W in the horizontal orientation with an evaporator temperature of 43.9 °C and efficiently dissipates a maximum heat load of 12 W without dry-out occurring. A minimum mLHP thermal resistance of 0.111 °C/W was achieved at a heat load of 11 W in a gravity favorable operation mode, at which the evaporator temperature was about 97.2 °C. In addition, an analytical analysis was conducted, and the devised equation could be used to evaluate the performance of the mLHP.

  3. Development and characterization of ultra-thin dosemeters of aluminium oxide

    International Nuclear Information System (INIS)

    Villagran V, E.

    2003-01-01

    The aim of the present thesis work has been to investigate the thermoluminescent (Tl) response of aluminium oxide thin films with thicknesses of the order of 300 nm prepared by laser ablation. Aluminium oxide thin films show Tl response after they are subject to ultraviolet, beta and gamma radiation. The Tl curves exhibit peaks around 75 C and 169 C for UV radiation, 112 C and 180 C for beta particles and 110 C and 176 C for gamma radiation. In order to improve the Tl response some growth parameters such as power density and distance target-substrate were varied. The relation dose-response shows a non-linear behavior for UV irradiation; a linear behavior for beta-particles dose from 150 mGy to 50 Gy, and a linear behavior for gamma radiation dose from 5 Gy to 100 Gy. The kinetic Tl parameters were determined by Computerized Glow Curve Deconvolution (CGCD) method as well as using analytical methods. The CGCD results show that the high temperature peak is composed by four peaks with maximums in 165.7, 188.1, 215.3, 246.5 C. These obey a second order kinetics. The trap depth (E) values are 1.4, 1.6, 1.8 and 2.0 eV respectively. The different analytical results show a trap depth values of 0.914, 0.82 and 0.656 eV respectively. Oxide aluminium thin films obtained would be a suitable tool owing to their potential applications in clinical dosimetry, in the dose distributions due to weekly penetrating radiation determination, and in interfaces dosimetry. (Author)

  4. An ultra-thin waveguide twist constructed using fish-scale metallic wires

    OpenAIRE

    Han, Jin; Li, Hongqiang; Fan, Yuancheng; Wei, Zeyong; Wu, Chao; Cao, Yang; Yu, Xing; Li, Fang; Wang, Zhanshan

    2011-01-01

    This study theoretically and experimentally investigates the transmission properties of a metamaterial slab comprised of two layers of metallic fish-scale structure arrays and a sandwiched dielectric layer. Calculations show that the asymmetric transmission can be tuned by varying the slab thickness, due to evanescent interlayer coupling. The spatial evolution of the local field inside the structure indicates that the slab functions as a perfect polarization transformer at certain frequencies...

  5. In-silico investigation of Rayleigh instability in ultra-thin copper nanowire in premelting regime

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Amlan [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700 098 (India); Chatterjee, Swastika; Raychaudhuri, A. K. [Unit for Nanoscience and Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700 098 (India); Moitra, Amitava [Thematic Unit of Excellence on Computational Materials Science, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700 098 (India); Saha-Dasgupta, T. [Thematic Unit of Excellence on Computational Materials Science, and Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700 098 (India)

    2014-06-28

    Motivated by the recent experimental reports, we explore the formation of Rayleigh-like instability in metallic nanowires during the solid state annealing, a concept originally introduced for liquid columns. Our molecular dynamics study using realistic interatomic potential reveals instability induced pattern formation at temperatures even below the melting temperature of the wire, in accordance with the experimental observations. We find that this is driven by the surface diffusion, which causes plastic slips in the system initiating necking in the nanowire. We further find the surface dominated mass-transport is of subdiffusive nature with time exponent less than unity. Our study provides an atomistic perspective of the instability formation in nanostructured solid phase.

  6. Preparation and characterization of ultra-thin sol-gel films

    International Nuclear Information System (INIS)

    Shapiro, Leora; Marx, Sharon; Mandler, Daniel

    2007-01-01

    The formation and characterization of nanometer thick sol-gel films are reported. The films were prepared by spin-coating of a diluted solution of a silane precursor on a number of different substrates. The effect of dilution, rotation speed and nature of substrate on the thickness and homogeneity of the films was examined. Characterization of the films was carried out by profilometry, reflectance spectroscopy, atomic force microscopy, adhesion test and electrochemistry. We find that the dilution factor has a pronounced effect on the film thickness. Moreover, the time of dilution, namely, whether dilution was carried out before or after a period of hydrolysis, has a noticeable effect on the thickness as well as on the permeability of embedded species

  7. Ultra thin buried oxide layers formed by low dose Simox process

    International Nuclear Information System (INIS)

    Aspar, B.; Pudda, C.; Papon, A.M.

    1994-01-01

    Oxygen low dose implantation is studied for two implantation energies. For 190 keV, a continuous buried oxide layer is obtained with a high dislocation density in the top silicon layer due to SiO 2 precipitates. For 120 keV, this silicon layer is free of SiO 2 precipitate and has a low dislocation density. Low density of pin-holes is observed in the buried oxide. The influence of silicon islands in the buried oxide on the breakdown electric fields is discussed. (authors). 6 refs., 5 figs

  8. Mirroring of 400 GeV/c protons by an ultra-thin straight crystal

    International Nuclear Information System (INIS)

    Scandale, W.; Arduini, G.; Butcher, M.; Cerutti, F.; Gilardoni, S.; Lechner, A.; Losito, R.; Masi, A.; Metral, E.; Mirarchi, D.; Montesano, S.; Redaelli, S.; Smirnov, G.; Bagli, E.; Bandiera, L.; Baricordi, S.; Dalpiaz, P.; Germogli, G.; Guidi, V.; Mazzolari, A.

    2014-01-01

    Channeling is the confinement of the trajectory of a charged particle in a crystalline solid. Positively charged particles channeled between crystal planes oscillate with a certain oscillation length, which depends on particle energy. A crystal whose thickness is half the oscillation length for planar channeling may act as a mirror for charged particles. If the incident angle of the particle trajectory with the crystal plane is less than the critical angle for channeling, under-barrier particles undergo half an oscillation and exit the crystal with the reversal of their transverse momentum, i.e., the particles are “mirrored” by the crystal planes. Unlike the traditional scheme relying on millimeter-long curved crystals, particle mirroring enables beam steering in high-energy accelerators via interactions with micrometer-thin straight crystal. The main advantage of mirroring is the interaction with a minimal amount of material along the beam, thereby decreasing unwanted incoherent nuclear interactions. The effectiveness of the mirror effect for ultrarelativistic positive particles has been experimentally proven at external lines of CERN-SPS. The mirroring effect in a 26.5-μm-thick Si crystal has been studied in the experiment with a narrow beam of 400 GeV/c protons at the CERN-SPS. The reflection efficiency for a quasi-parallel beam is larger than 80%

  9. Design of an ultra-thin near-eye display with geometrical waveguide and freeform optics.

    Science.gov (United States)

    Cheng, Dewen; Wang, Yongtian; Xu, Chen; Song, Weitao; Jin, Guofan

    2014-08-25

    Small thickness and light weight are two important requirements for a see-through near-eye display which are achieved in this paper by using two advanced technologies: geometrical waveguide and freeform optics. A major problem associated with the geometrical waveguide is the stray light which can severely degrade the display quality. The causes and solutions to this problem are thoroughly studied. A mathematical model of the waveguide is established and a non-sequential ray tracing algorithm is developed, which enable us to carefully examine the stray light of the planar waveguide and explore a global searching method to find an optimum design with the least amount of stray light. A projection optics using freeform surfaces on a wedge shaped prism is also designed. The near-eye display integrating the projection optics and the waveguide has a field of view of 28°, an exit pupil diameter of 9.6mm and an exit pupil distance of 20mm. In our final design, the proportion of the stray light energy over the image output energy of the waveguide is reduced to 2%, the modulation transfer function values across the entire field of the eyepiece are above 0.5 at 30 line pairs/mm (lps/mm). A proof-of-concept prototype of the proposed geometrical waveguide near-eye display is developed and demonstrated.

  10. Ultra-thin clay layers facilitate seismic slip in carbonate faults.

    Science.gov (United States)

    Smeraglia, Luca; Billi, Andrea; Carminati, Eugenio; Cavallo, Andrea; Di Toro, Giulio; Spagnuolo, Elena; Zorzi, Federico

    2017-04-06

    Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms -1 ) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms -1 ), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.

  11. Emergence of magnetic order in ultra-thin pyrochlore iridate films

    Science.gov (United States)

    Cheema, Suraj; Serrao, Claudy; Mundy, Julia; Patankar, Shreyas; Birgeneau, Robert; Orenstein, Joseph; Salahuddin, Sayeef; Ramesh, Ramamoorthy

    We report on thickness-dependent magnetotransport in (111) - oriented Pb2Ir2O7-x (Pb227) epitaxial thin films. For thicknesses greater than 4 nm, the magnetoresistance (MR) of metallic Pb227 is positive, linear and non-saturated up to 14 T. Meanwhile at 4 nm, the conduction turns nonmetallic and the MR becomes negative and asymmetric upon field-cooling; such traits are reminiscent of all-in-all-out (AIAO) magnetic order in the insulating pyrochlore iridates. Hysteretic low-field MR dips and trained-untrained resistivity bifurcations suggest the presence of magnetic conducting domain walls within the chiral AIAO spin structure. Beyond just AIAO order, angular-dependent MR indicates a magnetic phase space hosting 2-in-2-out (2I2O) spin ice order. Such anomalous magnetotransport calls for re-evaluation of the pyrochlore iridate phase diagram, as epitaxially strained Pb227 exhibits traits reminiscent of both the insulating magnetic and metallic spin-liquid members. Furthermore, these results open avenues for realizing topological phase predictions in (111) - oriented pyrochlore slabs of kagome-triangular iridate heterostructures. This work is supported by the Office of Basic Energy Sciences of the US Department of Energy under Contract No. DE-AC02-05CH11231.

  12. Solution-processing of ultra-thin CdTe/ZnO nanocrystal solar cells

    International Nuclear Information System (INIS)

    MacDonald, Brandon I.; Gengenbach, Thomas R.; Watkins, Scott E.; Mulvaney, Paul; Jasieniak, Jacek J.

    2014-01-01

    We have carried out a detailed study into how modifications of the physical, chemical and optical properties of solution-processed, nanocrystalline CdTe layers influence the photovoltaic performance of sintered CdTe/ZnO nanocrystal solar cells. Such solar cells are fabricated through layer-by-layer assembly, which is enabled through an inter layer chemical and thermal treatment cycle. In this manner we are able to fabricate working solar cells with sintered CdTe layers as low as 90 nm, provided that grain size is precisely controlled. We show that the extent of grain growth achieved during the CdTe sintering process is strongly dependent on nanocrystal surface chemistry and chemical environment, with the removal of the organic capping ligands and the introduction of CdCl 2 prior to annealing leading to greatly enhanced growth. Due to the air processing involved and the nanocrystalline nature of the CdTe, the overall performance of these solar cells is shown to be strongly dependent on both annealing temperature and time, with optimal results requiring a balance between crystal growth and degradation due to oxidation. Using this simple bi-layer device structure, optimized treatment conditions result in power conversion efficiencies of up to 7.7% and peak internal quantum efficiencies in excess of 95%. - Highlights: • We study the growth of nanocrystalline CdTe thin films from colloidal nanocrystals. • We examine the CdTe growth profiles as a function of surface chemistry. • We show that nanocrystalline CdTe is susceptible to oxidation under air annealing. • We show how this oxidation influences performance in CdTe/ZnO solar cells. • We demonstrate CdTe/ZnO solar cells with an efficiency of 7.7% fabricated in air

  13. Optical thin film deposition

    International Nuclear Information System (INIS)

    Macleod, H.A.

    1979-01-01

    The potential usefulness in the production of optical thin-film coatings of some of the processes for thin film deposition which can be classified under the heading of ion-assisted techniques is examined. Thermal evaporation is the process which is virtually universally used for this purpose and which has been developed to a stage where performance is in almost all respects high. Areas where further improvements would be of value, and the possibility that ion-assisted deposition might lead to such improvements, are discussed. (author)

  14. Radionuclide deposition control

    International Nuclear Information System (INIS)

    1980-01-01

    A method is described for controlling the deposition, on to the surfaces of reactor components, of the radionuclides manganese-54, cobalt-58 and cobalt-60 from a liquid stream containing the radionuclides. The method consists of disposing a getter material (nickel) in the liquid stream, and a non-getter material (tantalum, tungsten or molybdenum) as a coating on the surfaces where deposition is not desired. The process is described with special reference to its use in the coolant circuit in sodium cooled fast breeder reactors. (U.K.)

  15. Deposition potential of polonium

    Energy Technology Data Exchange (ETDEWEB)

    Heal, H. G.

    1948-11-23

    The cathodic deposition potential for polonium in concentrations of 10{sup -13} normal and 8 x 10{sup -13} normal, the former being 100-fold smaller than the smallest concentrations previously studied, has been determined. The value is 0.64 volt on the hydrogen scale. Considering the various ways in which the graphs can reasonably be drawn, we consider the maximum possible error to be of the order of +- 0.03 volt. There is apparently no shift of deposition potential between concentrations of 10{sup -8} and 10{sup -13} normal, indicating that the Nernst equation is not applicable in these circumstances.

  16. Reactive polymer fused deposition manufacturing

    Science.gov (United States)

    Kunc, Vlastimil; Rios, Orlando; Love, Lonnie J.; Duty, Chad E.; Johs, Alexander

    2017-05-16

    Methods and compositions for additive manufacturing that include reactive or thermosetting polymers, such as urethanes and epoxies. The polymers are melted, partially cross-linked prior to the depositing, deposited to form a component object, solidified, and fully cross-linked. These polymers form networks of chemical bonds that span the deposited layers. Application of a directional electromagnetic field can be applied to aromatic polymers after deposition to align the polymers for improved bonding between the deposited layers.

  17. Atomic Layer Deposition Re Ective Coatings For Future Astronomical Space Telescopes And The Solar Corona Viewed Through The Minxss (Miniature X-Ray Solar Spectrometer) Cubesats

    Science.gov (United States)

    Moore, Christopher Samuel

    2017-11-01

    Advances in technology and instrumentation open new windows for observing astrophysical objects. The first half of my dissertation involves the development of atomic layer deposition (ALD) coatings to create high reflectivity UV mirrors for future satellite astronomical telescopes. Aluminum (Al) has intrinsic reflectance greater than 80% from 90 – 2,000 nm, but develops a native aluminum oxide (Al2O3) layer upon exposure to air that readily absorbs light below 250 nm. Thus, Al based UV mirrors must be protected by a transmissive overcoat. Traditionally, metal-fluoride overcoats such as MgF2 and LiF are used to mitigate oxidation but with caveats. We utilize a new metal fluoride (AlF3) to protect Al mirrors deposited by ALD. ALD allows for precise thickness control, conformal and near stoichiometric thin films. We prove that depositing ultra-thin ( 3 nm) ALD ALF3 to protect Al mirrors after removing the native oxide layer via atomic layer etching (ALE) enhances the reflectance near 90 nm from 5% to 30%.X-ray detector technology with high readout rates are necessary for the relatively bright Sun, particularly during large flares. The hot plasma in the solar corona generates X-rays, which yield information on the physical conditions of the plasma. The second half of my dissertation includes detector testing, characterization and solar science with the Miniature X-ray Solar Spectrometer (MinXSS) CubeSats. The MinXSS CubeSats employ Silicon Drift Diode (SDD) detectors called X123, which generate full sun spectrally resolved ( 0.15 FWHM at 5.9 keV) measurements of the sparsely measured, 0.5 – 12 keV range. The absolute radiometric calibration of the MinXSS instrument suite was performed at the National Institute for Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility (SURF) and spectral resolution determined from radioactive sources. I used MinXSS along with data from the Geostationary Operational Environmental Satellites (GOES), Reuven Ramaty

  18. Effect of PbI{sub 2} deposition rate on two-step PVD/CVD all-vacuum prepared perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Ioakeimidis, Apostolos; Christodoulou, Christos; Lux-Steiner, Martha; Fostiropoulos, Konstantinos, E-mail: fostiropoulos@helmholtz-berlin.de

    2016-12-15

    In this work we fabricate all-vacuum processed methyl ammonium lead halide perovskite by a sequence of physical vapour deposition of PbI{sub 2} and chemical vapour deposition (CVD) of CH{sub 3}NH{sub 3}I under a static atmosphere. We demonstrate that for higher deposition rate the (001) planes of PbI{sub 2} film show a higher degree of alignment parallel to the sample's surface. From X-ray diffraction data of the resulted perovskite film we derive that the intercalation rate of CH{sub 3}NH{sub 3}I is fostered for PbI{sub 2} films with higher degree of (001) planes alignment. The stoichiometry of the produced perovskite film is also studied by Hard X-ray photoelectron spectroscopy measurements. Complete all-vacuum perovskite solar cells were fabricated on glass/ITO substrates coated by an ultra-thin (5 nm) Zn-phthalocyanine film as hole selective layer. A dependence of residual PbI{sub 2} on the solar cells performance is displayed, while photovoltaic devices with efficiency up to η=11.6% were achieved. - Graphical abstract: A two-step PVD/CVD processed perovskite film with the CVD intercalation rate of CH{sub 3}NCH{sub 3} molecules been fostered by increasing the PVD rate of PbI{sub 2} and prolonging the CVD time. - Highlights: • A simple PVD/CVD process for perovskite film production. • Increased PVD rate yields better alignment of the PbI{sub 2} (001) crystallite planes. • CH{sub 3}NH{sub 3}I intercalation process fostered by increased PbI{sub 2} PVD rate. • Stoichiometric CH{sub 3}NH{sub 3}PbI{sub 3} suitable as absorber in photovoltaic applications • Reduced PbI{sub 2} residue at the bottom of CH{sub 3}NH{sub 3}PbI{sub 3} improves device performance.

  19. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Guo, Wenlong [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Hongji, E-mail: hongjili@yeah.net [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Xu, Sheng [School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072 (China); Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2014-10-30

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na{sub 2}SO{sub 4} aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g{sup −1} at current density of 0.5 A g{sup −1}. The capacitance remains at about 84% after 1000 cycles at 10 A g{sup −1}. The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices.

  20. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    International Nuclear Information System (INIS)

    Li, Mingji; Guo, Wenlong; Li, Hongji; Xu, Sheng; Qu, Changqing; Yang, Baohe

    2014-01-01

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na 2 SO 4 aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g −1 at current density of 0.5 A g −1 . The capacitance remains at about 84% after 1000 cycles at 10 A g −1 . The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices

  1. Ion Deposited Carbon Coatings.

    Science.gov (United States)

    1983-07-01

    PAGE ("’hen Dita t,,I,, efl TABLE OF CONTENTS Section No. Title Page No. 1.0 OBJECTIVE 1 2.0 SCOPE 2 3.0 BACKGROUND 3 4.0 COATINGS DEPOSITION 4 4.1...scientific, ards of measure. The Committee, and Confer- technical, practical, and teaching purposes.ence voting members, are leading professional On the

  2. Plasma deposition of refractories

    International Nuclear Information System (INIS)

    Kudinov, V.V.; Ivanov, V.M.

    1981-01-01

    The problems of deposition, testing and application of plasma coating of refractory metals and oxides are considered. The process fundamentals, various manufacturing procedures and equipment for their realization are described in detail. Coating materials are given (Al, Mg, Al 2 O 3 , ZrO 2 , MgAlO 4 ) which are used in reactor engineering and their designated purposes are shown [ru

  3. 75 FR 34533 - Deposits

    Science.gov (United States)

    2010-06-17

    ... collection request (ICR) described below has been submitted to the Office of Management and Budget (OMB) for..., Attention: Desk Officer for OTS, U.S. Office of Management and Budget, 725 17th Street, NW., Room 10235... statement the institution sends to the consumer. Regulation DD contains rules for advertisements of deposit...

  4. 78 FR 56583 - Deposit Insurance Regulations; Definition of Insured Deposit

    Science.gov (United States)

    2013-09-13

    ... as a potential global deposit insurer, preserve confidence in the FDIC deposit insurance system, and... the United States.\\2\\ The FDIC generally pays out deposit insurance on the next business day after a... since 2001 and total approximately $1 trillion today. In many cases, these branches do not engage in...

  5. Uranium deposits of Zaire

    International Nuclear Information System (INIS)

    Kitmut, D.; Malu wa Kalenga

    1979-01-01

    Since April 1960, following the closing of the Shinkolobwe mine, the Republic of Zaire has ceased to be a producer of uranium. Nevertheless, Gecamines (Generale des carrieres et mines du Zaire), a wholly state-owned company, is continuing its research on uranium occurrences which have been discovered in its concession in the course of aerial radiometric prospecting. The most recent campaign was the one carried out in 1969 and 1972 by Hunting Company. On-the-ground verification of these shows has not yet resulted in the discovery of a workable deposit. There are other sectors cutting across Zaire which might well contain uranium deposits: this is true of the sedimentary phosphates of the region of Lower Zaire as well as of the frontier region between Zaire and the Central African Empire. However, no detailed exploration work has yet been carried out. (author)

  6. 20 CFR 703.306 - Kinds of negotiable securities that may be deposited; conditions of deposit; acceptance of deposits.

    Science.gov (United States)

    2010-04-01

    ... the Act in the amount fixed by the Office under the regulations in this part shall deposit any... deposited; conditions of deposit; acceptance of deposits. 703.306 Section 703.306 Employees' Benefits... negotiable securities that may be deposited; conditions of deposit; acceptance of deposits. A self-insurer or...

  7. Thorium ore deposits

    International Nuclear Information System (INIS)

    Angelelli, Victorio.

    1984-01-01

    The main occurences of the thorium minerals of the Argentine Republic which have not been exploited, due to their reduced volume, are described. The thoriferous deposits have three genetic types: pegmatitic, hydrothermal and detritic, being the most common minerals: monazite, thorite and thorogummite. The most important thorium accumulations are located in Salta, being of less importance those of Cordoba, Jujuy and San Juan. (M.E.L.) [es

  8. Electrophoretic deposition of biomaterials

    Science.gov (United States)

    Boccaccini, A. R.; Keim, S.; Ma, R.; Li, Y.; Zhitomirsky, I.

    2010-01-01

    Electrophoretic deposition (EPD) is attracting increasing attention as an effective technique for the processing of biomaterials, specifically bioactive coatings and biomedical nanostructures. The well-known advantages of EPD for the production of a wide range of microstructures and nanostructures as well as unique and complex material combinations are being exploited, starting from well-dispersed suspensions of biomaterials in particulate form (microsized and nanoscale particles, nanotubes, nanoplatelets). EPD of biological entities such as enzymes, bacteria and cells is also being investigated. The review presents a comprehensive summary and discussion of relevant recent work on EPD describing the specific application of the technique in the processing of several biomaterials, focusing on (i) conventional bioactive (inorganic) coatings, e.g. hydroxyapatite or bioactive glass coatings on orthopaedic implants, and (ii) biomedical nanostructures, including biopolymer–ceramic nanocomposites, carbon nanotube coatings, tissue engineering scaffolds, deposition of proteins and other biological entities for sensors and advanced functional coatings. It is the intention to inform the reader on how EPD has become an important tool in advanced biomaterials processing, as a convenient alternative to conventional methods, and to present the potential of the technique to manipulate and control the deposition of a range of nanomaterials of interest in the biomedical and biotechnology fields. PMID:20504802

  9. Radionuclides deposition over Antarctica

    International Nuclear Information System (INIS)

    Pourchet, M.; Magand, O.; Frezzotti, M.; Ekaykin, A.; Winther, J.-G.

    2003-01-01

    A detailed and comprehensive map of the distribution patterns for both natural and artificial radionuclides over Antarctica has been established. This work integrates the results of several decades of international programs focusing on the analysis of natural and artificial radionuclides in snow and ice cores from this polar region. The mean value (37±20 Bq m -2 ) of 241 Pu total deposition over 28 stations is determined from the gamma emissions of its daughter 241 Am, presenting a long half-life (432.7 yrs). Detailed profiles and distributions of 241 Pu in ice cores make it possible to clearly distinguish between the atmospheric thermonuclear tests of the fifties and sixties. Strong relationships are also found between radionuclide data ( 137 Cs with respect to 241 Pu and 210 Pb with respect to 137 Cs), make it possible to estimate the total deposition or natural fluxes of these radionuclides. Total deposition of 137 Cs over Antarctica is estimated at 760 TBq, based on results from the 90-180 deg. East sector. Given the irregular distribution of sampling sites, more ice cores and snow samples must be analyzed in other sectors of Antarctica to check the validity of this figure

  10. Novel precursors for the deposition of rare earth oxides

    International Nuclear Information System (INIS)

    Ahlers, Mareike

    2010-01-01

    During this work rare earth solvates with nitrate and perchlorate anions have been investigated. All compounds have been structurally characterized and analyzed using thermal gravimetric analysis. The decomposition residues were analyzed using powder diffraction methods. Almost all compounds showed a characteristically intense exothermic decomposition step during the thermal decomposition, most likely caused by an intramolecular redox reaction between the nitrate or perchlorate anion respectively and the organic solvent molecules. The nitrates RE(NO 3 ) 3 (CH(OCH 3 ) 3 ) 2 (RE = Sm, Eu) were isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. The known compound group of dimethoxyethane solvates was then expanded with RE(NO 3 ) 3 (O 2 C 4 H 10 ) (RE = La, Sm, Eu). Considering the possible use as precursor material the already described neodymium compound is also discussed. The thermal decomposition of these compounds yields the respective cubic rare earth oxide and shows the typical intense exothermic decomposition reaction. A variety of different precursor system based on nitrate solvates for the deposition of rare earth oxide layers on a silicon surface was developed and investigated in collaboration with the group of Prof. Dr. Al-Shamery (Univ. Oldenburg). Ultra thin films on a H-Si(111) surface were obtained via the deposition of the precursor, which was dissolved in organic solvents. An oxide layer was detected after the heating of the sample. The film thickness was measured as < 10 nm, whereas the thickness of the film was controlled by the concentration of the precursor solution. Sm(ClO 4 ) 3 (CH(OCH 3 ) 3 ) 3 was isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. Eu(ClO 4 ) 3 (CH(OCH 3 ) 3 ) 2 (MeOH) 2 was obtained without recrystallization. The methanol molecules, formed during the hydrolysis of the trimethyl

  11. Deposition and Resuspension of Particles

    DEFF Research Database (Denmark)

    Lengweiler, P.; Nielsen, Peter V.; Moser, A.

    A new experimental set-up to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airBorne dust concentration considerably. As a basis for developing methods to eliminate dust related problems in rooms......, there is a need for better understanding of the mechanism of dust deposition and resuspension....

  12. A Micrometeorological Perspective on Deposition

    DEFF Research Database (Denmark)

    Jensen, Niels Otto

    1981-01-01

    An expression for the dry deposition velocity is given in terms of constant flux layer scaling. Numerical values of upper bounds on the deposition velocity is given for a typical situation. Some remarks are then offered on the relative merits of various ways in which the combined diffusion-deposition...

  13. Market Discipline and Deposit Insurance

    OpenAIRE

    Peresetsky, Anatoly

    2008-01-01

    The paper examines Russian banks’ household deposit interest rates for the transition period of setting up the deposit insurance system. Monthly observations of Russian banks’ interest rates and balance sheets are used in a fixed effects panel data model. It is shown market discipline has been significantly diminished after switching to the deposit insurance.

  14. Electrophoretic Deposition of Gallium with High Deposition Rate

    Directory of Open Access Journals (Sweden)

    Hanfei Zhang

    2014-12-01

    Full Text Available In this work, electrophoretic deposition (EPD is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher than the typical value reported for electroplating, is obtained when employing a set of proper deposition parameters. The thickness of the film is shown to increase with deposition time when sequential deposition is employed. The concentration of Mg(NO32, the charging salt, is also found to be a critical factor to control the deposition rate. Various gallium micropatterns are obtained by masking the substrate during the process, demonstrating process compatibility with microfabrication. The reported novel approach can potentially be employed in a broad range of applications with Ga as a raw material, including microelectronics, photovoltaic cells, and flexible liquid metal microelectrodes.

  15. Dry deposition on urban surfaces

    International Nuclear Information System (INIS)

    Roed, J.

    1985-01-01

    In order to facilitate developing a model for deposition in urban areas, beryllium-7, created by cosmic radiation and fall-out cesium-137, have been used as tracers in measurements designed to find the dry deposition velocity on building surfaces. A literature review has revealed that very little work has been done on deposition in urban areas; therefore, a major effort on meausring the deposition parameter is needed to construct reliable models in this field. Deposition velocities in the range from 0.001-0.04 cm/s have been found. (author)

  16. Thermal plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Heberlein, J.; Pfender, E.

    1993-01-01

    Thermal plasmas, with temperatures up to and even exceeding 10 4 K, are capable of producing high density vapor phase precursors for the deposition of relatively thick films. Although this technology is still in its infancy, it will fill the void between the relatively slow deposition processes such as physical vapor deposition and the high rate thermal spray deposition processes. In this chapter, the present state-of-the-art of this field is reviewed with emphasis on the various types of reactors proposed for this emerging technology. Only applications which attracted particular attention, namely diamond and high T c superconducting film deposition, are discussed in greater detail. (orig.)

  17. Uranium ore deposits

    International Nuclear Information System (INIS)

    Angelelli, Victorio.

    1984-01-01

    The main uranium deposits and occurrences in the Argentine Republic are described, considering, in principle, their geologic setting, the kind of 'model' of the mineralization and its possible origin, and describing the ore species present in each case. The main uraniferous accumulations of the country include the models of 'sandstong type', veintype and impregnation type. There are also other kinds of accumulations, as in calcrete, etc. The main uranium production has been registered in the provinces of Mendoza, Salta, La Rioja, Chubut, Cordoba and San Luis. In each case, the minerals present are mentioned, having been recognized 37 different species all over the country (M.E.L.) [es

  18. Deposition of carbon dioxide

    International Nuclear Information System (INIS)

    2001-01-01

    In Norway, there is currently a debate about whether or not to build gas power stations. To meet the possibility of reduced emission quotas for carbon dioxide in the future, current interest focuses on the incorporation of large-scale separation and deposition of carbon dioxide when such plants are planned. A group of experts concludes that this technology will become self-financing by means of environmental taxes. From the environmental point of view, taxes upon production are to be preferred over taxes on consumption

  19. Stratigraphic implications of uranium deposits

    International Nuclear Information System (INIS)

    Langford, F.F.

    1980-01-01

    One of the most consistent characteristics of economic uranium deposits is their restricted stratigraphic distribution. Uraninite deposited with direct igneous affiliation contains thorium, whereas chemical precipitates in sedimentary rocks are characterized by thorium-free primary uranium minerals with vanadium and selenium. In marine sediments, these minerals form low-grade disseminations; but in terrestrial sediments, chiefly fluvial sandstones, the concentration of uranium varies widely, with the high-grade portions constituting ore. Pitchblende vein deposits not only exhibit the same chemical characteristics as the Colorado-type sandstone deposits, but they have a stratigraphically consistent position at unconformities covered by fluvial sandstones. If deposits in such diverse situations have critical features in common, they are likely to have had many features of their origin in common. Thus, vein deposits in Saskatchewan and Australia may have analogues in areas that contain Colorado-type sandstone deposits. In New Mexico, the presence of continental sandstones with peneconformable uranium deposits should also indicate good prospecting ground for unconformity-type vein deposits. All unconformities within the periods of continental deposition ranging from Permian to Cretaceous should have uranium potential. Some situations, such as the onlap of the Abo Formation onto Precambrian basement in the Zuni Mountains, may be directly comparable to Saskatchewan deposition. However, uranium occurrences in the upper part of the Entrada Sandstone suggest that unconformities underlain by sedimentary rocks may also be exploration targets

  20. Sandstone-type uranium deposits

    International Nuclear Information System (INIS)

    Austin, S.R.; D'Andrea, R.F. Jr.

    1978-01-01

    Three overall factors are necessary for formation of uranium deposits in sandstone: a source of uranium, host rocks capable of transmitting uranium-bearing solutions, and a precipitant. Possible sources of uranium in sandstone-type deposits include groundwaters emanating from granitic highlands, arkosic sediments, tuffaceous material within or overlying the host rocks, connate fluids, and overlying black shales. The first three sources are considered the most likely. Host rocks are generally immature sandstones deposited in alluvial-fan, intermontane-basin or marginal-marine environments, but uranium deposits do occur in well-winnowed barrier-bar or eolian sands. Host rocks for uranium deposits generally show coefficients of permeability on the order of 1 to 100 gal/day/ft 2 . Precipitants are normally agents capable of reducing uranium from the uranyl to the uranous state. The association of uranium with organic matter is unequivocal; H 2 S, a powerful reductant, may have been present at the time of formation of some deposits but may go unnoticed today. Vanadium can serve to preserve the tabular characteristics of some deposits in the near-surface environment, but is considered an unlikely primary precipitant for uranium. Uranium deposits in sandstone are divided into two overall types: peneconcordant deposits, which occur in locally reducing environments in otherwise oxidized sandstones; and roll-type deposits, which occur at the margin of an area where an oxidized groundwater has permeated an otherwise reduced sandstone. Uranium deposits are further broken down into four subclasses; these are described

  1. Geological factors of deposit formation

    International Nuclear Information System (INIS)

    Grushevoj, G.V.

    1980-01-01

    Geologic factors of hydrogenic uranium deposit formation are considered. Structural, formation and lithological-facies factors of deposit formation, connected with zones of stratal oxidation, are characterized. Peculiarities of deposit localization, connected with orogenic structures of Mesozoic and lenozoic age, are described. It is noted that deposits of anagenous group are widely spread in Paleozoic formations, infiltration uranium deposits are localized mainly in Cenozoic sediments, while uranium mineralization both anagenous and infiltration groups are widely developed in Mesozoic sediments. Anagenous deposits were formed in non-oxygen situation, their age varies from 200 to 55 mln years. Infiltration deposit formation is determined by asymmetric oxidation zonation, their age varies from 10 - 40 mln years to dozens of thousand years [ru

  2. FDIC Summary of Deposits (SOD) Download File

    Data.gov (United States)

    Federal Deposit Insurance Corporation — The FDIC's Summary of Deposits (SOD) download file contains deposit data for branches and offices of all FDIC-insured institutions. The Federal Deposit Insurance...

  3. Plutonium in uranium deposits

    International Nuclear Information System (INIS)

    Curtis, D.; Fabryka-Martin, J.; Aguilar, R.; Attrep, M. Jr.; Roensch, F.

    1992-01-01

    Plutonium-239 (t 1/2 , 24,100 yr) is one of the most persistent radioactive constituents of high-level wastes from nuclear fission power reactors. Effective containment of such a long-lived constituent will rely heavily upon its containment by the geologic environment of a repository. Uranium ore deposits offer a means to evaluate the geochemical properties of plutonium under natural conditions. In this paper, analyses of natural plutonium in several ores are compared to calculated plutonium production rates in order to evaluate the degree of retention of plutonium by the ore. The authors find that current methods for estimating production rates are neither sufficiently accurate nor precise to provide unambiguous measures of plutonium retention. However, alternative methods for evaluating plutonium mobility are being investigated, including its measurement in natural ground waters. Preliminary results are reported and establish the foundation for a comprehensive characterization of plutonium geochemistry in other natural environments

  4. Classification of Uranium deposits

    International Nuclear Information System (INIS)

    Dahlkamp, F.J.

    1978-01-01

    A listing of the recognized types of uranium mineralization shows nineteen determinable types out of which only six can be classified as of economic significance at present: Oligomiitic quartz pebble conglomerates, sandstone types, calcretes, intra-intrusive types, hydrothermal veins, veinlike types. The different types can be genetically related to prevalent geological environments, i.e. 1. the primary uranium occurrences formed by endogenic processes, 2. the secondary derived from the primary by subsequent exogenic processes, 3. the tertiary occurrences are assumed to be formed by endogenic metamorphic processes, although little is known about the behaviour of the uranium during the metamorphosis and therefore the metallogenesis of this tertiary uranium generation is still vague. A metallotectonic-geochronologic correlation of the uranium deposits shows a distinct affinity of the uranium to certain geological epochs: The Upper Archean, Lower Proterozoic, the Hercynian and, in a less established stage, the Upper Proterozoic. (orig.) 891 HP/orig. 892 MKO [de

  5. Locating underground uranium deposits

    International Nuclear Information System (INIS)

    Felice, P.E.

    1979-01-01

    Underground uranium deposits are located by placing wires of dosimeters each about 5 to 18 mg/cm 2 thick underground in a grid pattern. Each dosimeter contains a phosphor which is capable of storing the energy of alpha particles. In each pair one dosimeter is shielded from alpha particles with more than 18 mg/cm 2 thick opaque material but not gamma and beta rays and the other dosimeter is shielded with less than 1 mg/cm 2 thick opaque material to exclude dust. After a period underground the dosimeters are heated which releases the stored energy as light. The amount of light produced from the heavily shielded dosimeter is subtracted from the amount of light produced from the thinly shielded dosimeter to give an indication of the location and quantity of uranium underground

  6. Global deposition of airborne dioxin.

    Science.gov (United States)

    Booth, Shawn; Hui, Joe; Alojado, Zoraida; Lam, Vicky; Cheung, William; Zeller, Dirk; Steyn, Douw; Pauly, Daniel

    2013-10-15

    We present a global dioxin model that simulates one year of atmospheric emissions, transport processes, and depositions to the earth's terrestrial and marine habitats. We map starting emission levels for each land area, and we also map the resulting deposits to terrestrial and marine environments. This model confirms that 'hot spots' of deposition are likely to be in northern Europe, eastern North America, and in parts of Asia with the highest marine dioxin depositions being the northeast and northwest Atlantic, western Pacific, northern Indian Ocean and the Mediterranean. It also reveals that approximately 40% of airborne dioxin emissions are deposited to marine environments and that many countries in Africa receive more dioxin than they produce, which results in these countries being disproportionately impacted. Since human exposure to dioxin is largely through diet, this work highlights food producing areas that receive higher atmospheric deposits of dioxin than others. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. A remote coal deposit revisited

    DEFF Research Database (Denmark)

    Bojesen-Kofoed, Jørgen A.; Kalkreuth, Wolfgang; Petersen, Henrik I.

    2012-01-01

    discovery. The outcrops found in 2009 amount to approximately 8 m of sediment including a coal seam of 2 m thickness. More outcrops and additional coal deposits most certainly are to be found, pending further fieldwork. The deposits are Middle Jurassic, Callovian, in age and were deposited in a floodplain...... environment related to meandering river channels. Spores and pollen in the lower fluvial deposits reflect abundant vegetation of ferns along the river banks. In contrast, a sparse spore and pollen flora in the coals show a mixed vegetation of ferns and gymnosperms. Based on proximate and petrographic analyses...

  8. 76 FR 41392 - Interest on Deposits; Deposit Insurance Coverage

    Science.gov (United States)

    2011-07-14

    ... banks' funding costs and also allow them to plan business growth more dependably and rigorously... of business deposits by offering continually higher rates of interest. Three of the four contended... deposits. They reasoned that large banks will offer high rates of interest and lure away business...

  9. Uranium deposits in granitic rocks

    International Nuclear Information System (INIS)

    Nishimori, R.K.; Ragland, P.C.; Rogers, J.J.W.; Greenberg, J.K.

    1977-01-01

    This report is a review of published data bearing on the geology and origin of uranium deposits in granitic, pegmatitic and migmatitic rocks with the aim of assisting in the development of predictive criteria for the search for similar deposits in the U.S. Efforts were concentrated on the so-called ''porphyry'' uranium deposits. Two types of uranium deposits are primarily considered: deposits in pegmatites and alaskites in gneiss terrains, and disseminations of uranium in high-level granites. In Chapter 1 of this report, the general data on the distribution of uranium in igneous and metamorphic rocks are reviewed. Chapter 2 contains some comments on the classification of uranium deposits associated with igneous rocks and a summary of the main features of the geology of uranium deposits in granites. General concepts of the behavior of uranium in granites during crustal evolution are reviewed in Chapter 3. Also included is a discussion of the relationship of uranium mineralization in granites to the general evolution of mobile belts, plus the influence of magmatic and post-magmatic processes on the distribution of uranium in igneous rocks and related ore deposits. Chapter 4 relates the results of experimental studies on the crystallization of granites to some of the geologic features of uranium deposits in pegmatites and alaskites in high-grade metamorphic terrains. Potential or favorable areas for igneous uranium deposits in the U.S.A. are delineated in Chapter 5. Data on the geology of specific uranium deposits in granitic rocks are contained in Appendix 1. A compilation of igneous rock formations containing greater than 10 ppM uranium is included in Appendix 2. Appendix 3 is a report on the results of a visit to the Roessing area. Appendix 4 is a report on a field excursion to eastern Canada

  10. Enhanced nitrogen deposition over China

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xuejun; Zhang, Ying; Han, Wenxuan; Tang, Aohan; Shen, Jianlin; Cui, Zhenling; Christie, Peter; Zhang, Fusuo [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Vitousek, Peter [Department of Biology, Stanford University, Stanford, California 94305 (United States); Erisman, Jan Willem [VU University Amsterdam, 1081 HV Amsterdam (Netherlands); Goulding, Keith [The Sustainable Soils and Grassland Systems Department, Rothamsted Research, Harpenden AL5 2JQ (United Kingdom); Fangmeier, Andreas [Institute of Landscape and Plant Ecology, University of Hohenheim, 70593 Stuttgart (Germany)

    2013-02-28

    China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P < 0.001) between the 1980s (13.2 kilograms of nitrogen per hectare) and the 2000s (21.1 kilograms of nitrogen per hectare). Nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s, before the introduction of mitigation measures. Nitrogen from ammonium (NH4+) is the dominant form of N in bulk deposition, but the rate of increase is largest for deposition of N from nitrate (NO3-), in agreement with decreased ratios of NH3 to NOx emissions since 1980. We also find that the impact of N deposition on Chinese ecosystems includes significantly increased plant foliar N concentrations in natural and semi-natural (that is, non-agricultural) ecosystems and increased crop N uptake from long-term-unfertilized croplands. China and other economies are facing a continuing challenge to reduce emissions of reactive nitrogen, N deposition and their negative effects on human health and the environment.

  11. Liquefier Dynamics in Fused Deposition

    DEFF Research Database (Denmark)

    Bellini, Anna; Guceri, Selcuk; Bertoldi, Maurizio

    2004-01-01

    Layered manufacturing (LM) is an evolution of rapid prototyping (RP) technology whereby a part is built in layers. Fused deposition modeling (FDM) is a particular LM technique in which each section is fabricated through vector style deposition of building blocks, called roads, which...

  12. NURE uranium deposit model studies

    International Nuclear Information System (INIS)

    Crew, M.E.

    1981-01-01

    The National Uranium Resource Evaluation (NURE) Program has sponsored uranium deposit model studies by Bendix Field Engineering Corporation (Bendix), the US Geological Survey (USGS), and numerous subcontractors. This paper deals only with models from the following six reports prepared by Samuel S. Adams and Associates: GJBX-1(81) - Geology and Recognition Criteria for Roll-Type Uranium Deposits in Continental Sandstones; GJBX-2(81) - Geology and Recognition Criteria for Uraniferous Humate Deposits, Grants Uranium Region, New Mexico; GJBX-3(81) - Geology and Recognition Criteria for Uranium Deposits of the Quartz-Pebble Conglomerate Type; GJBX-4(81) - Geology and Recognition Criteria for Sandstone Uranium Deposits in Mixed Fluvial-Shallow Marine Sedimentary Sequences, South Texas; GJBX-5(81) - Geology and Recognition Criteria for Veinlike Uranium Deposits of the Lower to Middle Proterozoic Unconformity and Strata-Related Types; GJBX-6(81) - Geology and Recognition Criteria for Sandstone Uranium Deposits of the Salt Wash Type, Colorado Plateau Province. A unique feature of these models is the development of recognition criteria in a systematic fashion, with a method for quantifying the various items. The recognition-criteria networks are used in this paper to illustrate the various types of deposits

  13. Sandstone-type uranium deposits

    International Nuclear Information System (INIS)

    Finch, W.I.; Davis, J.F.

    1985-01-01

    World-class sandstone-type uranium deposits are defined as epigenetic concentrations of uranium minerals occurring as uneven impregnations and minor massive replacements primarily in fluvial, lacustrine, and deltaic sandstone formations. The main purpose of this introductory paper is to define, classify, and introduce to the general geologic setting for sandstone-type uranium deposits

  14. Laser deposition of HTSC films

    International Nuclear Information System (INIS)

    Sobol', Eh.N.; Bagratashvili, V.N.; Zherikhin, A.N.; Sviridov, A.P.

    1990-01-01

    Studies of the high-temperature superconducting (HTSC) films fabrication by the laser deposition are reviewed. Physical and chemical processes taking place during laser deposition are considered, such as the target evaporation, the material transport from the target to the substrate, the film growth on the substrate, thermochemical reactions and mass transfer within the HTSC films and their stability. The experimental results on the laser deposition of different HTSC ceramics and their properties investigations are given. The major technological issues are discussed including the deposition schemes, the oxygen supply, the target compositions and structure, the substrates and interface layers selection, the deposition regimes and their impact on the HTSC films properties. 169 refs.; 6 figs.; 2 tabs

  15. Polymer deposition morphology by electrospray deposition - Modifications through distance variation

    International Nuclear Information System (INIS)

    Altmann, K.; Schulze, R.-D.; Friedrich, J.

    2014-01-01

    Electrospray deposition (ESD) of highly diluted polymers was examined with regard to the deposited surface structure. Only the flight distance (flight time) onto the resulting deposited surface was varied from 20 to 200 mm. An apparatus without any additional heating or gas flows was used. Polyacrylic acid (PAA) and polyallylamine (PAAm) in methanol were deposited on Si wafers. The polymer layers were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, derivatization reactions and Fourier transform infrared spectroscopy using a grazing incidence unit. SEM images illustrated the changing structures of PAA and PAAm. For PAA the deposited structure changed from a smooth film (20 mm) to a film with individual droplets on the coated surface (100 mm and 200 mm), while for PAAm individual droplets can be seen at all distances. The ESD process with cascades of splitting droplets slows down for PAA after distances greater than 40 mm. In contrast, the ESD process for PAAm is nearly stopped within the first flight distance of 20 mm. Residual solvent analysis showed that most of the solvent evaporated within the first 20 mm capillary-sample distance. - Highlights: • We deposited polyacrylic acid and polyallylamine by electrospray ionization (ESI). • The morphology in dependence of flight distance (20 mm to 200 mm) was analyzed. • The amount of residual solvent after deposition was determined. • ESI-process slows down for polyacrylic acid after 40 mm flight distance. • ESI-Process is complete for polyallylamine within the first 20 mm

  16. 20 CFR 703.207 - Kinds of negotiable securities that may be deposited; conditions of deposit; acceptance of deposits.

    Science.gov (United States)

    2010-04-01

    ... amount fixed by the Office under the regulations in this part shall deposit any negotiable securities... deposited; conditions of deposit; acceptance of deposits. 703.207 Section 703.207 Employees' Benefits... AND RELATED STATUTES INSURANCE REGULATIONS Insurance Carrier Security Deposit Requirements § 703.207...

  17. Surface deposition from radioactive plumes

    International Nuclear Information System (INIS)

    Garland, J.A.

    1980-01-01

    Accidents involving nuclear plants may release radioactive particles and gases to the atmosphere. Dry deposition of particles has been investigated mainly in the laboratory and a general understanding of the transfer mechanisms has been established. However there is apparently a substantial discrepancy between the few field observations of dry deposition of particles and laboratory measurements, particularly for 0.1 - 1 μm particles for which laboratory work shows very small deposition rates. In addition there are few estimates of deposition rates for forest and some other kinds of terrain. The most important gas in the context of a nuclear accident is I-131 and the behaviour of this gas at grass surfaces has received much attention. However smaller quantities of other gases and vapours may be released and the surface absorption of these species may require further investigation. In addition there is little knowledge of the behaviour of gases over many types of surface. The rate of deposition of particles and gases is influenced by many parameters including wind speed and the temperature stratification of the lower atmosphere. Conditions which give poor atmospheric dispersion usually give lower deposition velocities. Transfer to man depends on the availability of deposited materials on crops and grass. A wide range of isotopes including iodine and several metallic fission products are lost with a half life for residence on grass ranging from a few days to a few tens days, depending on climatic conditions

  18. ITO thin films deposited by advanced pulsed laser deposition

    International Nuclear Information System (INIS)

    Viespe, Cristian; Nicolae, Ionut; Sima, Cornelia; Grigoriu, Constantin; Medianu, Rares

    2007-01-01

    Indium tin oxide thin films were deposited by computer assisted advanced PLD method in order to obtain transparent, conductive and homogeneous films on a large area. The films were deposited on glass substrates. We studied the influence of the temperature (room temperature (RT)-180 deg. C), pressure (1-6 x 10 -2 Torr), laser fluence (1-4 J/cm 2 ) and wavelength (266-355 nm) on the film properties. The deposition rate, roughness, film structure, optical transmission, electrical conductivity measurements were done. We deposited uniform ITO thin films (thickness 100-600 nm, roughness 5-10 nm) between RT and 180 deg. C on a large area (5 x 5 cm 2 ). The films have electrical resistivity of 8 x 10 -4 Ω cm at RT, 5 x 10 -4 Ω cm at 180 deg. C and an optical transmission in the visible range, around 89%

  19. Atmospheric deposition 2000. NOVA 2003; Atmosfaerisk deposition 2000. NOVA 2003

    Energy Technology Data Exchange (ETDEWEB)

    Ellermann, T.; Hertel, O.; Hovmand, M.F.; Kemp, K.; Skjoeth, C.A.

    2001-11-01

    This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2000. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorus and sulphur compounds related to eutrophication and acidification. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. Measurements: In 2000 the monitoring program consisted of eight stations where wet deposition of ammonium, nitrate, phosphate (semi quantitatively) and sulphate were measured using bulk precipitation samplers. Six of the stations had in addition measurements of atmospheric content of A, nitrogen, phosphorus, and sulphur compounds in gas and particulate phase carried out by use of filter pack samplers. Filters were analysed at the National Environmental Research Institute. Furthermore nitrogen dioxide were measured using nitrogen dioxide filter samplers and monitors. Model calculations: The measurements in the monitoring program were supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surface, marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data as input. The advantage of combining measurements with model calculations is that the strengths of both methods is obtained. Conclusions concerning: 1) actual concentration levels at the monitoring stations, 2) deposition at the monitoring stations, 3) seasonal variations and 4) long term trends in concentrations and depositions are mainly based on the direct measurements. These are furthermore used to validate the results of the model calculations. Calculations and conclusions concerning: 1) depositions to land surface and to the individual marine water, 2) contributions from different emission

  20. Particle deposition in ventilation ducts

    Energy Technology Data Exchange (ETDEWEB)

    Sippola, Mark Raymond [Univ. of California, Berkeley, CA (United States)

    2002-09-01

    Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 μm were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the