WorldWideScience

Sample records for film large area

  1. Large Area Single Crystal (0001) Oriented MoS2 Thin Films

    OpenAIRE

    Laskar, Masihhur R.; Ma, Lu; K, ShanthaKumar; Park, Pil Sung; Krishnamoorthy, Sriram; Nath, Digbijoy N.; Lu, Wu; Wu, Yiying; Rajan, Siddharth

    2013-01-01

    Layered metal dichalcogenide materials are a family of semiconductors with a wide range of energy band gaps and properties, and potential to open up new areas of physics and technology applications. However, obtaining high crystal quality thin films over a large area remains a challenge. Here we show that chemical vapor deposition (CVD) can be used to achieve large area electronic grade single crystal Molybdenum Disulfide (MoS2) thin films with the highest mobility reported in CVD grown films...

  2. Preparation of Super-Thin, Large-Area, Double-Sided Gold-Plated Mylar Film

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Large-area multi-wire parallel plane avalanche counter (MWPPAC) is a kind of gas detector widely used in nuclear experiments. MWPPAC is composed of front-window film, X wires, anode film, Y wires and rear-window film, which is mostly utilized to measuring

  3. Transferred metal electrode films for large-area electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jin-Guo [Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Medical Drive, Singapore S117456 (Singapore); Kam, Fong-Yu [Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); Chua, Lay-Lay [Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore); Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117543 (Singapore)

    2014-11-10

    The evaporation of metal-film gate electrodes for top-gate organic field-effect transistors (OFETs) limits the minimum thickness of the polymer gate dielectric to typically more than 300 nm due to deep hot metal atom penetration and damage of the dielectric. We show here that the self-release layer transfer method recently developed for high-quality graphene transfer is also capable of giving high-quality metal thin-film transfers to produce high-performance capacitors and OFETs with superior dielectric breakdown strength even for ultrathin polymer dielectric films. Dielectric breakdown strengths up to 5–6 MV cm{sup −1} have been obtained for 50-nm thin films of polystyrene and a cyclic olefin copolymer TOPAS{sup ®} (Zeon). High-quality OFETs with sub-10 V operational voltages have been obtained this way using conventional polymer dielectrics and a high-mobility polymer semiconductor poly[2,5-bis(3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene-2,5-diyl]. The transferred metal films can make reliable contacts without damaging ultrathin polymer films, self-assembled monolayers and graphene, which is not otherwise possible from evaporated or sputtered metal films.

  4. Large area growth of layered WSe2 films

    Science.gov (United States)

    Browning, Robert; Kuperman, Neal; Solanki, Raj; Kanzyuba, Vasily; Rouvimov, Sergei

    2016-09-01

    Growth of smooth and continuous films of WSe2 has been demonstrated by employing atomic layer deposition (ALD) on 5 cm × 5 cm substrates. The substrates consisted of silicon wafers with a layer of SiO2. The ALD precursors were WCl5 and H2Se. The film properties characterized using Raman spectroscopy and x-ray photoelectron spectroscopy are comparable to those reported for WSe2 films produced by chemical vapor deposition and exfoliation. Carrier mobilities were determined with back-gated transistors. With Pd contacts, median electron and hole mobilities of 531 cm2 V-1 s-1 and 354 cm2 V-1 s-1, respectively, were measured.

  5. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 12...

  6. Large area radiation detectors based on II VI thin films

    Science.gov (United States)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  7. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo

    2017-05-08

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  8. Preparation of Large Area Double Sided YBCO Thin Films by DC Magneton Sputtering

    Institute of Scientific and Technical Information of China (English)

    Li Tao; Gu Hongwei; Wang Peiwen; Wang Xiaoping; Xie Bowei

    2004-01-01

    Tc, Jc and Rs properties of large area double sided YBCO thin films deposited on LaAlO3 substrates by direct current sputtering were reported.Film thickness of the obtained thin films is over 300 nm, Tc > 90 K; Rs can be as low as less than 1.0 mΩ(77 K, 10 GHz).Homogenousity of the properties around the plane was studied.Under the measnous distributions.Influences of substrate temperature and Ar and O2 pressures on properties of the double-sided thin films were discussed.

  9. [Preparation of large area Al-ZnO thin film by DC magnetron sputtering].

    Science.gov (United States)

    Jiao, Fei; Liao, Cheng; Han, Jun-Feng; Zhou, Zhen

    2009-03-01

    Solar cells of p-CIS/n-buffer/ZnO type, where CIS is (CuInS2, CuInSe2 or intermediates, are thin-film-based devices for the future high-efficiency and low-cost photovoltaic devices. As important thin film, the properties of Al-doped ZnO (AZO) directly affect the parameter of the cell, especially for large volume. In the present paper, AZO semiconductor transparent thin film on soda-lime glass was fabricated using cylindrical zinc-aluminum target, which can not only lower the cost of the target but also make the preparation of large area AZO thin film more easily. Using the DC magnet sputtering techniques and rolling target, high utilization efficiency of target was achieved and large area uniform and directional film was realized. An introduction to DC magnet sputtering techniques for large area film fabrication is given. With different measurement methods, such as X-ray diffraction (XRD) and scan electron microscope (SEM), we analyzed large size film's structure, appearance, and electrical and optical characteristics. The XRD spectrum indicated that the AZO film shows well zinc-blende structure with a preferred (002) growth and the c-axis is oriented normal to the substrate plane. The lattice constant is 5.603 9 nm and the mismatch with CdS thin film is only 2 percent. It absolutely satisfied the demand of the GIGS solar cell. The cross-section of the AZO thin film indicates the columnar structure and the surface morphology shows that the crystal size is about 50 nm that is consistent with the result of XRD spectrum. By the optical transmission curve, not only the high transmission rate over 85 percent in the visible spectrum between 400 nm and 700 nm was showed but also the band gap 3.1 eV was estimated. And all these parameters can meet the demand of the large area module of GIGS solar cell. The result is that using alloy target and Ar gas, and controlling the appropriate pressure of oxygen, we can get directional, condensed, uniform, high transmitting rate, low

  10. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films.

    OpenAIRE

    Cho, N; Li, F; Turedi, B; Sinatra, L; Sarmah, SP; Parida,, B.; Saidaminov, MI; Murali, B; Burlakov, VM; Goriely, Alain; Mohammed, OF; Wu, T; Bakr, OM

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microa...

  11. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    OpenAIRE

    Cho, Namchul; LI Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Murali, Banavoth; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F; Wu, Tom; Bakr, Osman M.

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microa...

  12. Nanotechnological Advances in Catalytic Thin Films for Green Large-Area Surfaces

    Directory of Open Access Journals (Sweden)

    Suzan Biran Ay

    2015-01-01

    Full Text Available Large-area catalytic thin films offer great potential for green technology applications in order to save energy, combat pollution, and reduce global warming. These films, either embedded with nanoparticles, shaped with nanostructuring techniques, hybridized with other systems, or functionalized with bionanotechnological methods, can include many different surface properties including photocatalytic, antifouling, abrasion resistant and mechanically resistive, self-cleaning, antibacterial, hydrophobic, and oleophobic features. Thus, surface functionalization with such advanced structuring methods is of significance to increase the performance and wide usage of large-area thin film coatings specifically for environmental remediation. In this review, we focus on methods to increase the efficiency of catalytic reactions in thin film and hence improve the performance in relevant applications while eliminating high cost with the purpose of widespread usage. However, we also include the most recent hybrid architectures, which have potential to make a transformational change in surface applications as soon as high quality and large area production techniques are available. Hence, we present and discuss research studies regarding both organic and inorganic methods that are used to structure thin films that have potential for large-area and eco-friendly coatings.

  13. Gold-film coating assisted femtosecond laser fabrication of large-area, uniform periodic surface structures.

    Science.gov (United States)

    Feng, Pin; Jiang, Lan; Li, Xin; Rong, Wenlong; Zhang, Kaihu; Cao, Qiang

    2015-02-20

    A simple, repeatable approach is proposed to fabricate large-area, uniform periodic surface structures by a femtosecond laser. 20 nm gold films are coated on semiconductor surfaces on which large-area, uniform structures are fabricated. In the case study of silicon, cross-links and broken structures of laser induced periodic surface structures (LIPSSs) are significantly reduced on Au-coated silicon. The good consistency between the scanning lines facilitates the formation of large-area, uniform LIPSSs. The diffusion of hot electrons in the Au films increases the interfacial carrier densities, which significantly enhances interfacial electron-phonon coupling. High and uniform electron density suppresses the influence of defects on the silicon and further makes the coupling field more uniform and thus reduces the impact of laser energy fluctuations, which homogenizes and stabilizes large-area LIPSSs.

  14. Large-area graphene films by simple solution casting of edge-selectively functionalized graphite.

    Science.gov (United States)

    Bae, Seo-Yoon; Jeon, In-Yup; Yang, Jieun; Park, Noejung; Shin, Hyeon Suk; Park, Sungjin; Ruoff, Rodney S; Dai, Liming; Baek, Jong-Beom

    2011-06-28

    We report edge-selective functionalization of graphite (EFG) for the production of large-area uniform graphene films by simply solution-casting EFG dispersions in dichloromethane on silicon oxide substrates, followed by annealing. The resultant graphene films show ambipolar transport properties with sheet resistances of 0.52-3.11 kΩ/sq at 63-90% optical transmittance. EFG allows solution processing methods for the scalable production of electrically conductive, optically transparent, and mechanically robust flexible graphene films for use in practice.

  15. Terahertz and M4PP conductivity mapping of large area CVD grown graphene films

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due; Petersen, Dirch Hjorth; Bøggild, Peter;

    We demonstrate mapping of magnitude and variation of the electrical conductance of large area CVD graphene films by terahertz time-domain spectroscopy (THz-TDS) and micro four-point-probe (M4PP). Non-trivial correlations between results obtained with the two techniques are discussed in relation...

  16. Thickness determination of large-area films of yttria-stabilized zirconia produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, N.; Christensen, Bo Toftmann; Bilde-Sørensen, Jørgen;

    2006-01-01

    Films of yuria-stabilized zirconia (YSZ) on a polished silicon substrate of diameter up to 125 mm have been produced in a large-area pulsed laser deposition (PLD) setup under typical PLD conditions. The film thickness over the full film area has been determined by energy-dispersive Xray spectrome...

  17. Structural and electrical properties of large area epitaxial VO2 films grown by electron beam evaporation

    Science.gov (United States)

    Théry, V.; Boulle, A.; Crunteanu, A.; Orlianges, J. C.; Beaumont, A.; Mayet, R.; Mennai, A.; Cosset, F.; Bessaudou, A.; Fabert, M.

    2017-02-01

    Large area (up to 4 squared inches) epitaxial VO2 films, with a uniform thickness and exhibiting an abrupt metal-insulator transition with a resistivity ratio as high as 2.85 × 10 4 , have been grown on (001)-oriented sapphire substrates by electron beam evaporation. The lattice distortions (mosaicity) and the level of strain in the films have been assessed by X-ray diffraction. It is demonstrated that the films grow in a domain-matching mode where the distortions are confined close to the interface which allows growth of high-quality materials despite the high film-substrate lattice mismatch. It is further shown that a post-deposition high-temperature oxygen annealing step is crucial to ensure the correct film stoichiometry and provide the best structural and electrical properties. Alternatively, it is possible to obtain high quality films with a RF discharge during deposition, which hence do not require the additional annealing step. Such films exhibit similar electrical properties and only slightly degraded structural properties.

  18. Large-Area Buckled MoS2 Films on the Graphene Substrate.

    Science.gov (United States)

    Kim, Seon Joon; Kim, Dae Woo; Lim, Joonwon; Cho, Soo-Yeon; Kim, Sang Ouk; Jung, Hee-Tae

    2016-06-01

    In this study, a novel buckled structure of edge-oriented MoS2 films is fabricated for the first time by employing monolayer graphene as the substrate for MoS2 film growth. Compared to typical buckling methods, our technique has several advantages: (1) external forces such as heat and mechanical strain are not applied; (2) uniform and controllable buckling over a large area is possible; and (3) films are able to be transferred to a desired substrate. Dual MoS2 orientation was observed in the buckled film where horizontally aligned MoS2 layers of 7 nm thickness were present near the bottom graphene surface and vertically aligned layers dominated the film toward the outer surface, in which the alignment structure was uniform across the entire film. The catalytic ability of the buckled MoS2 films, measured by performing water-splitting tests in acidic environments, shows a reduced onset potential of -0.2 V versus reversible hydrogen electrode (RHE) compared to -0.32 V versus RHE for pristine MoS2, indicating that the rough surface provided a higher catalytic activity. Our work presents a new method to generate a buckled MoS2 structure, which may be extended to the formation of buckled structures in various 2D materials for future applications.

  19. Thin film cadmium telluride charged particle sensors for large area neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J. W.; Smith, L.; Calkins, J.; Mejia, I.; Cantley, K. D.; Chapman, R. A.; Quevedo-Lopez, M.; Gnade, B., E-mail: gnade@utdallas.edu [Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States); Kunnen, G. R.; Allee, D. R. [Flexible Display Center, Arizona State University, Phoenix, Arizona 85284 (United States); Sastré-Hernández, J.; Contreras-Puente, G. [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Mexico City 07738 (Mexico); Mendoza-Pérez, R. [Universidad Autónoma de la Ciudad de México, Mexico City 09790 (Mexico)

    2014-09-15

    Thin film semiconductor neutron detectors are an attractive candidate to replace {sup 3}He neutron detectors, due to the possibility of low cost manufacturing and the potential for large areas. Polycrystalline CdTe is found to be an excellent material for thin film charged particle detectors—an integral component of a thin film neutron detector. The devices presented here are characterized in terms of their response to alpha and gamma radiation. Individual alpha particles are detected with an intrinsic efficiency of >80%, while the devices are largely insensitive to gamma rays, which is desirable so that the detector does not give false positive counts from gamma rays. The capacitance-voltage behavior of the devices is studied and correlated to the response due to alpha radiation. When coupled with a boron-based neutron converting material, the CdTe detectors are capable of detecting thermal neutrons.

  20. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying

    2013-06-02

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach - termed fluid-enhanced crystal engineering (FLUENCE) - that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s -1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. © 2013 Macmillan Publishers Limited. All rights reserved.

  1. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains.

    Science.gov (United States)

    Diao, Ying; Tee, Benjamin C-K; Giri, Gaurav; Xu, Jie; Kim, Do Hwan; Becerril, Hector A; Stoltenberg, Randall M; Lee, Tae Hoon; Xue, Gi; Mannsfeld, Stefan C B; Bao, Zhenan

    2013-07-01

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach--termed fluid-enhanced crystal engineering (FLUENCE)--that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm(2) V(-1) s(-1) and 11 cm(2) V(-1) s(-1). FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics.

  2. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    Science.gov (United States)

    Diao, Ying; Tee, Benjamin C.-K.; Giri, Gaurav; Xu, Jie; Kim, Do Hwan; Becerril, Hector A.; Stoltenberg, Randall M.; Lee, Tae Hoon; Xue, Gi; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2013-07-01

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach—termed fluid-enhanced crystal engineering (FLUENCE)—that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s-1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics.

  3. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    KAUST Repository

    Cho, Nam Chul

    2016-11-10

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm−3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices.

  4. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    Science.gov (United States)

    Cho, Namchul; Li, Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Murali, Banavoth; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F.; Wu, Tom; Bakr, Osman M.

    2016-11-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 1013 cm-3) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices.

  5. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer.

    Science.gov (United States)

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-03-12

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications.

  6. Probing large area surface plasmon interference in thin metal films using photon scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Passian, A.; Wig, A.; Lereu, A.L.; Evans, P.G.; Meriaudeau, F.; Thundat, T.; Ferrell, T.L

    2004-08-15

    The interference of surface plasmons can provide important information regarding the surface features of the hosting thin metal film. We present an investigation of the interference of optically excited surface plasmons in the Kretschmann configuration in the visible spectrum. Large area surface plasmon interference regions are generated at several wavelengths and imaged with the photon scanning tunneling microscope. Furthermore, we discuss the non-retarded dispersion relations for the surface plasmons in the probe-metal system modeled as confocal hyperboloids of revolution in the spheroidal coordinate systems.

  7. Large area Germanium Tin nanometer optical film coatings on highly flexible aluminum substrates

    Science.gov (United States)

    Jin, Lichuan; Zhang, Dainan; Zhang, Huaiwu; Fang, Jue; Liao, Yulong; Zhou, Tingchuan; Liu, Cheng; Zhong, Zhiyong; Harris, Vincent G.

    2016-09-01

    Germanium Tin (GeSn) films have drawn great interest for their visible and near-infrared optoelectronics properties. Here, we demonstrate large area Germanium Tin nanometer thin films grown on highly flexible aluminum foil substrates using low-temperature molecular beam epitaxy (MBE). Ultra-thin (10–180 nm) GeSn film-coated aluminum foils display a wide color spectra with an absorption wavelength ranging from 400–1800 nm due to its strong optical interference effect. The light absorption ratio for nanometer GeSn/Al foil heterostructures can be enhanced up to 85%. Moreover, the structure exhibits excellent mechanical flexibility and can be cut or bent into many shapes, which facilitates a wide range of flexible photonics. Micro-Raman studies reveal a large tensile strain change with GeSn thickness, which arises from lattice deformations. In particular, nano-sized Sn-enriched GeSn dots appeared in the GeSn coatings that had a thickness greater than 50 nm, which induced an additional light absorption depression around 13.89 μm wavelength. These findings are promising for practical flexible photovoltaic and photodetector applications ranging from the visible to near-infrared wavelengths.

  8. Electrically tunable terahertz metamaterials with embedded large-area transparent thin-film transistor arrays.

    Science.gov (United States)

    Xu, Wei-Zong; Ren, Fang-Fang; Ye, Jiandong; Lu, Hai; Liang, Lanju; Huang, Xiaoming; Liu, Mingkai; Shadrivov, Ilya V; Powell, David A; Yu, Guang; Jin, Biaobing; Zhang, Rong; Zheng, Youdou; Tan, Hark Hoe; Jagadish, Chennupati

    2016-03-22

    Engineering metamaterials with tunable resonances are of great importance for improving the functionality and flexibility of terahertz (THz) systems. An ongoing challenge in THz science and technology is to create large-area active metamaterials as building blocks to enable efficient and precise control of THz signals. Here, an active metamaterial device based on enhancement-mode transparent amorphous oxide thin-film transistor arrays for THz modulation is demonstrated. Analytical modelling based on full-wave techniques and multipole theory exhibits excellent consistent with the experimental observations and reveals that the intrinsic resonance mode at 0.75 THz is dominated by an electric response. The resonant behavior can be effectively tuned by controlling the channel conductivity through an external bias. Such metal/oxide thin-film transistor based controllable metamaterials are energy saving, low cost, large area and ready for mass-production, which are expected to be widely used in future THz imaging, sensing, communications and other applications.

  9. Transparent conductive film by large area roll-to-roll processing

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Linda Y.L., E-mail: ylwu@simtech.a-star.edu.sg [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Kerk, W.T. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Wong, C.C. [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2013-10-01

    Sputtered indium tin oxide (ITO) coating on polyethylene terephthalate film has been used as the substrate for roll-to-roll fabrication of large area printed electronics devices, but it is expensive and could be cracked when bending, limiting its applications. Transparent conductive (TC) electrode made by roll-to-roll coating of transparent conductive ink on flexible substrate is an alternative, but both the ink material and the control of the coating quality are very crucial. The major challenges are the coating performance, coating uniformity and defect control during roll-to-roll processing. In this paper, we report the chemical synthesis of silver nanowires in preferred shape and size, the surface modification of the Ag nanowires for better dispersion into the commercial Poly(3,4-ethylenedioxythiophene) Poly(styrenesulfonate) (PEDOT:PSS) conductive polymer ink, and the controlled roll-to-roll coating process on flexible polyethylene terephthalate substrate by a one meter web-width roll-to-roll slot die coating system. We obtained high uniformity PEDOT:PSS coating with optical transmission higher than 80% and sheet resistance lower than 100 Ω/square, and silver containing coating with sheet resistance below 40 Ω/square and maintained optical transmittance. The slot die coating mechanism is investigated and the influencing factors for coating uniformity and defect are defined. The coated transparent conductive film has the same properties as the sputtered ITO and has been used as the TC electrode for printed lighting, whose performance has been proven by standard weathering test for 1000 h. - Highlight: • Controlled synthesis of silver nanowires using trace amount of Cl{sup −} ions • Large area roll-to-roll processed transparent conductive (TC) coatings • TC film has light transmission > 80% and sheet resistance < 100 Ω/sq. • Silver containing ink achieved better property than conductive polymer ink. • Used as the TC electrode for printed

  10. Large area and low power dielectrowetting optical shutter with local deterministic fluid film breakup

    Science.gov (United States)

    Zhao, R.; Cumby, B.; Russell, A.; Heikenfeld, J.

    2013-11-01

    A large area (>10 cm2) and low-power (0.1-10 Hz AC voltage, ˜10's μW/cm2) dielectrowetting optical shutter requiring no pixelation is demonstrated. The device consists of 40 μm interdigitated electrodes covered by fluid splitting features and a hydrophobic fluoropolymer. When voltage is removed, the fluid splitting features initiate breakup of the fluid film into small droplets resulting in ˜80% transmission. Both the dielectrowetting and fluid splitting follow theory, allowing prediction of alternate designs and further improved performance. Advantages include scalability, optical polarization independence, high contrast ratio, fast response, and simple construction, which could be of use in switchable windows or transparent digital signage.

  11. Single-step holographic fabrication of large-area periodically corrugated metal films.

    Science.gov (United States)

    Lu, Mengqian; Krishna Juluri, Bala; Zhao, Yanhui; Jun Liu, Yan; Bunning, Timothy J; Jun Huang, Tony

    2012-12-01

    We have developed a simple, high-throughput, and cost-effective method to fabricate one-dimensional and two-dimensional periodically corrugated silver films over centimeter scale areas. This fabrication uses a single-step holographic patterning technique with laser intensities as low as 88.8 mW/cm(2) to deposit silver nanoparticles directly from solution to create gratings with periodicities of 570 nm. A dip in the transmission spectrum for these samples is observed due to certain visible wavelengths coupling to surface plasmon polaritons (SPPs) and the peak wavelength of this dip has a linear relationship with the surrounding material's refractive index (RI) with a sensitivity of 553.4 nm/RIU. The figure of merit (the ratio of refractive index sensitivity to the full width at half maximum (FWHM)) is typically in the range of 12-23. Our technique enables single-step fabrication of uniform, sub-wavelength periodic metal structures over a large area with low cost. Such sub-wavelength periodic metal structures are promising candidates as disposable sensors in applications such as affordable environmental monitoring systems and point-of-care diagnostics.

  12. Uniformity in large area ZnO:Al films prepared by reactive midfrequency magnetron sputtering

    CERN Document Server

    Hong, R J; Sittinger, V; Szyszka, B; Hoeing, T; Bräuer, G; Heide, G; Frischat, G H

    2002-01-01

    Al-doped zinc oxide (ZnO:Al) films were deposited on glass substrates using a reactive midfrequency magnetron sputtering process. The optical transmission and reflection as well as the electrical resistivity of the films prepared on an area of 1000x600 mm sup 2 were determined at different locations. Films with a uniform distribution of resistivity between 2.9x10 sup - sup 4 and 3.6x10 sup - sup 4 OMEGA cm and transmittance up to 88% in the visible spectral range were obtained. The ellipsometric spectra of the films were also analyzed using the Drude-Lorentz model. The calculated thicknesses of the films agreed well with those measured by a step profilometer. Secondary neutral mass spectrometry depth profiling showed uniform contents of Zn and O elements, while a slight periodic variation of the Al content was observed at different depths inside the film. A transition zone of 35-55 nm in width between the films and glass substrates due to the interdiffusion was also observed.

  13. Hot embossing holographic images in BOPP shrink films through large-area roll-to-roll nanoimprint lithography

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Menglin; Lin, Shiwei, E-mail: linsw@hainu.edu.cn; Jiang, Wenkai; Pan, Nengqian

    2014-08-30

    Highlights: • High-quality holographic images were replicated in large-area shrink film. • Surface morphology evolution was analyzed in films embossed at different temperatures. • Optical, mechanical, and thermal characteristics were systematically analyzed. - Abstract: Diffraction grating-based holographic images have been successfully replicated in biaxially oriented polypropylene (BOPP) shrink films through large-area roll-to-roll nanoimprint technique. Such hot embossing of holographic images on BOPP films represents a promising means of creating novel security features in packaging applications. The major limitation of the high-quality replication is the relatively large thermal shrinkage of BOPP shrink film. However, although an appropriate shrinkage is demanded after embossing, over-shrinking not only causes distortion in embossed images, but also reduces the various properties of BOPP shrink films mainly due to the disappearance of orientation. The effects of embossing temperature on the mechanical, thermal and optical properties as well as polymer surface morphologies were systematically analyzed. The results show that the optimal process parameters are listed as follows: the embossing temperature at 104–110 °C, embossing force 6 kg/cm{sup 2} and film speed 32 m/min. The variation in flow behavior of polymer surface during hot embossing process is highly dependent on the temperature. In addition, the adhesion from the direct contact between the rubber press roller and polymer surfaces is suggested to cause the serious optical properties failure.

  14. Large area ion beam sputtered YBa2Cu3O(7-delta) films for novel device structures

    Science.gov (United States)

    Gauzzi, A.; Lucia, M. L.; Kellett, B. J.; James, J. H.; Pavuna, D.

    1992-03-01

    A simple single-target ion-beam system is employed to manufacture large areas of uniformly superconducting YBa2Cu3O(7-delta) films which can be reproduced. The required '123' stoichiometry is transferred from the target to the substrate when ion-beam power, target/ion-beam angle, and target temperature are adequately controlled. Ion-beam sputtering is experimentally demonstrated to be an effective technique for producing homogeneous YBa2Cu3O(7-delta) films.

  15. Application of CBD-Zinc Sulfide Film as an Antireflection Coating on Very Large Area Multicrystalline Silicon Solar Cell

    Directory of Open Access Journals (Sweden)

    U. Gangopadhyay

    2007-01-01

    Full Text Available The low-cost chemical bath deposition (CBD technique is used to prepare CBD-ZnS films as antireflective (AR coating for multicrystalline silicon solar cells. The uniformity of CBD-ZnS film on large area of textured multicrystalline silicon surface is the major challenge of CBD technique. In the present work, attempts have been made for the first time to improve the rate of deposition and uniformity of deposited film by controlling film stoichiometry and refractive index and also to minimize reflection loss by proper optimization of molar percentage of different chemical constituents and deposition conditions. Reasonable values of film deposition rate (12.13 Å′/min., good film uniformity (standard deviation <1, and refractive index (2.35 along with a low percentage of average reflection (6-7% on a textured mc-Si surface are achieved with proper optimization of ZnS bath. 12.24% efficiency on large area (125 mm × 125 mm multicrystalline silicon solar cells with CBD-ZnS antireflection coating has been successfully fabricated. The viability of low-cost CBD-ZnS antireflection coating on large area multicrystalline silicon solar cell in the industrial production level is emphasized.

  16. Continued improvment of large area, in situ sputter deposition of superconducting YBCO thin films

    Science.gov (United States)

    Truman, J. K.; White, W. R.; Ballentine, P. H.; Mallory, D. S.; Kadin, A. M.

    1993-01-01

    The deposition of thin films of superconducting YBa2Cu3O7-x onto substrates of up to 3-in diameter by an integrated off-axis sputtering is reported. The substrate is located above the center of an 8-in-diameter YBCO planar target, and, in conjunction with a negative ion shield, negative ion effects are avoided. A large radiant heater provides backside, noncontact heating of the bare substrates. YBCO films have been grown on polished 1-cm2 MgO and LaAlO3 substrates with Tc = 90 K or greater, Jc = 2.5 x 10 exp 6 A/sq cm or greater at 77 K, and microwave surface resistance Rs less than 0.4 micro-ohm at 77 K and 10 GHz. The films have a very smooth surface morphology. Uniformity data for LaAlO3 substrates are less than +/-5 percent in Rs. Thickness uniformity results for 3-in substrates indicate less than 10 percent variation. The growth of epitaxial insulating films for use with YBCO films and application of the YBCO films in microwave devices are briefly discussed.

  17. Defect-Free Large-Area (25 cm2 Light Absorbing Perovskite Thin Films Made by Spray Coating

    Directory of Open Access Journals (Sweden)

    Mehran Habibi

    2017-03-01

    Full Text Available In this work, we report on reproducible fabrication of defect-free large-area mixed halide perovskite (CH3NH3PbI3−xClx thin films by scalable spray coating with the area of 25 cm2. This is essential for the commercialization of the perovskite solar cell technology. Using an automated spray coater, the film thickness and roughness were optimized by controlling the solution concentration and substrate temperature. For the first time, the surface tension, contact angle, and viscosity of mixed halide perovskite dissolved in dimethylformamide (DMF are reported as a function of the solution concentration. A low perovskite solution concentration of 10% was selected as an acceptable value to avoid crystallization dewetting. The determined optimum substrate temperature of 150 °C, followed by annealing at 100 °C render the highest perovskite precursor conversion, as well as the highest possible droplet spreading, desired to achieve a continuous thin film. The number of spray passes was also tuned to achieve a fully-covered film, for the condition of the spray nozzle used in this work. This work demonstrates that applying the optimum substrate temperature decreases the standard deviation of the film thickness and roughness, leading to an increase in the quality and reproducibility of the large-area spray-on films. The optimum perovskite solution concentration and the substrate temperature are universally applicable to other spray coating systems.

  18. Fabrication and radio frequency test of large-area MgB2 films on niobium substrates

    Science.gov (United States)

    Ni, Zhimao; Guo, Xin; Welander, Paul B.; Yang, Can; Franzi, Matthew; Tantawi, Sami; Feng, Qingrong; Liu, Kexin

    2017-04-01

    Magnesium diboride (MgB2) is a promising candidate material for superconducting radio frequency (RF) cavities because of its higher transition temperature and critical field compared with niobium. To meet the demand of RF test devices, the fabrication of large-area MgB2 films on metal substrates is needed. In this work, high quality MgB2 films with 50 mm diameter were fabricated on niobium by using an improved HPCVD system at Peking University, and RF tests were carried out at SLAC National Accelerator Laboratory. The transition temperature is approximately 39.6 K and the RF surface resistance is about 120 μΩ at 4 K and 11.4 GHz. The fabrication processes, surface morphology, DC superconducting properties and RF tests of these large-area MgB2 films are presented.

  19. Optimization of large area YBa 2Cu 3O 7-x films by single target ion beam sputtering

    Science.gov (United States)

    Gauzzi, A.; Lucia, M. L.; Affronte, M.; Pavuna, D.

    1991-12-01

    We report on the in-situ growth over large area of high-quality homogeneous YBa 2Cu 3O 7-x films by single target ion beam sputtering. The ‘123’ stoichiometry transfer to the substrates is obtained by using sufficiently low power ion beam and a grazing angle between the ion beam and the target. The as-deposited films show consistent homogeneity and reproducible superconducting properties (ΔT c10 6 A cm -2 at 77 K) over areas larger than ≈30 cm 2.

  20. Large-area monocrystalline silicon thin films by annealing of macroporous arrays: Understanding and tackling defects in the material

    Science.gov (United States)

    Depauw, Valérie; Gordon, Ivan; Beaucarne, Guy; Poortmans, Jef; Mertens, Robert; Celis, Jean-Pierre

    2009-08-01

    A concept that could provide a thin monocrystalline-silicon absorber layer without resorting to the expensive step of epitaxy would be very appealing for reducing the cost of solar cells. The empty-space-in-silicon technique by which thin films of silicon can be formed by reorganization of regular arrays of cylindrical voids at high temperature may be such a concept if the high quality of the thin film could be ensured on centimeter-large areas. While previous works mainly investigated the influence of the porous array on the final structure, this work focuses on the practical aspects of the high-temperature step and its application to large areas. An insight into the defects that may form is given and the origin of these defects is discussed, providing recommendations on how to avoid them. Surface roughening, pitting, formation of holes, and silicon pillars could be attributed to the nonuniform reactions between Si, SiO2, and SiO. Hydrogen atmospheres are therefore preferred for reorganization of macroporous arrays. Argon atmospheres, however, may provide high-quality silicon thin films as well, possibly even more easily transferable, as long as annealing is performed in controlled, clean, and oxygen-free conditions. Our experiments on large areas also highlight the importance of kinetics, which had not been considered up to now and which will require further understanding to ensure a complete reorganization over any wafer area.

  1. Hot embossing holographic images in BOPP shrink films through large-area roll-to-roll nanoimprint lithography

    Science.gov (United States)

    Jiang, Menglin; Lin, Shiwei; Jiang, Wenkai; Pan, Nengqian

    2014-08-01

    Diffraction grating-based holographic images have been successfully replicated in biaxially oriented polypropylene (BOPP) shrink films through large-area roll-to-roll nanoimprint technique. Such hot embossing of holographic images on BOPP films represents a promising means of creating novel security features in packaging applications. The major limitation of the high-quality replication is the relatively large thermal shrinkage of BOPP shrink film. However, although an appropriate shrinkage is demanded after embossing, over-shrinking not only causes distortion in embossed images, but also reduces the various properties of BOPP shrink films mainly due to the disappearance of orientation. The effects of embossing temperature on the mechanical, thermal and optical properties as well as polymer surface morphologies were systematically analyzed. The results show that the optimal process parameters are listed as follows: the embossing temperature at 104-110 °C, embossing force 6 kg/cm2 and film speed 32 m/min. The variation in flow behavior of polymer surface during hot embossing process is highly dependent on the temperature. In addition, the adhesion from the direct contact between the rubber press roller and polymer surfaces is suggested to cause the serious optical properties failure.

  2. Enhanced Self-Organized Dewetting of Ultrathin Polymer Blend Film for Large-Area Fabrication of SERS Substrate

    Science.gov (United States)

    Zhang, Huanhuan; Xu, Lin; Xu, Yabo; Huang, Gang; Zhao, Xueyu; Lai, Yuqing; Shi, Tongfei

    2016-12-01

    We study the enhanced dewetting of ultrathin Polystyrene (PS)/Poly (methyl methacrylate) (PMMA) blend films in a mixed solution, and reveal the dewetting can act as a simple and effective method to fabricate large-area surface-enhanced Raman scattering (SERS) substrate. A bilayer structure consisting of under PMMA layer and upper PS layer forms due to vertical phase separation of immiscible PS/PMMA during the spin-coating process. The thicker layer of the bilayer structure dominates the dewetting structures of PS/PMMA blend films. The diameter and diameter distribution of droplets, and the average separation spacing between the droplets can be precisely controlled via the change of blend ratio and film thickness. The dewetting structure of 8 nm PS/PMMA (1:1 wt%) blend film is proved to successfully fabricate large-area (3.5 cm × 3.5 cm) universal SERS substrate via deposited a silver layer on the dewetting structure. The SERS substrate shows good SERS-signal reproducibility (RSD promote the application of SERS substrate in the rapid sensitive detection of trace molecules.

  3. Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices.

    Science.gov (United States)

    Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

    2016-06-03

    Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W(-1), external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

  4. Direct synthesis of large-area continuous ReS2 films on a flexible glass at low temperature

    Science.gov (United States)

    Kim, Youngchan; Kang, Byunggil; Choi, Yongsuk; Cho, Jeong Ho; Lee, Changgu

    2017-06-01

    Rhenium disulfide (ReS2) has been attracting attentions due to the direct bandgap regardless of the thickness and anisotropic electrical, mechanical and optical properties deriving from its unique crystal lattice structure. In order to utilize these properties, some synthesis methods of ReS2 have been studied for electronic applications. However, their results are not suitable for practical applications because of non-uniformity, discontinuity and difficulty of large-area continuous film growth. Here, we report the synthesis method of layer-controlled wafer-scale (7  ×  2 cm2) ReS2 films by chemical vapor deposition with high uniformity and continuity. Especially, we demonstrate successfully a direct synthesis of ReS2 on a transparent flexible glass substrate at low synthesis temperature (450 °C) without the aid of a catalyst or a plasma enhanced system. The field effect transistors with as-grown ReS2 films on the flexible glass exhibit typical n-type behavior with low threshold voltage of 0.75 V, high on-off ratio of ~105, low subthreshold swing of 260 mV/decade and mobility of 0.13 cm2 V-1 S-1. The direct synthesis of ReS2 films on flexible glass will provide the platform to realize large area transfer-free fabrication of high quality transparent flexible electronic devices.

  5. High quality MgB{sub 2} thick films and large-area films fabricated by hybrid physical-chemical vapor deposition with a pocket heater

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S F; Chen, Ke; Li, Qi; Xi, X X [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Lee, C-H; Soukiassian, A; DeFrain, R; Redwing, J M; Schlom, D G [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Lamborn, D R [Department of Chemical Engineering, Pennsylvania State University, University Park, PA 16802 (United States)], E-mail: suw16@psu.edu

    2008-08-15

    A hybrid physical-chemical vapor deposition process using a pocket heater was developed for the growth of high quality epitaxial large-area MgB{sub 2} thin films and c-axis textured MgB{sub 2} thick films. This technique is able to independently control the substrate and Mg source temperatures and maintain sufficient Mg overpressure to ensure phase stability. The two-inch large-area MgB{sub 2} thin films showed uniform superconducting properties with the superconducting transition temperature T{sub c} of about 40 K, residual resistivity ratio (RRR) of about 10, and critical current density J{sub c} of about 10{sup 7} A cm{sup -2} (0 T, 5 K). The thick films ({approx}10 {mu}m) on sapphire substrates showed a maximum T{sub c} of 40 K and RRR of 15, and a J{sub c} of 1.6 x 10{sup 6} A cm{sup -2} at low applied magnetic fields even at 20 K. High quality thick films also have been obtained on metal substrates.

  6. Large-Area, Freestanding MOF Films of Planar, Curvilinear, or Micropatterned Topographies.

    Science.gov (United States)

    Yoon, Seok Min; Park, Jun Heuk; Grzybowski, Bartosz A

    2017-01-02

    Freestanding MOF films up to six-inches across and replicating various surface (micro)patterns are prepared via a templated growth method. When grown on copper supports, these films have preferred orientation of the constituent crystallites, translating into markedly different wetting properties of the film's two surfaces (water-pinning vs. water repellant). In addition, the films exhibit differential sorption of various organic solvents, can recover oil spills from seawater, and can also act as active layers of chemical sensors.

  7. Large Area Thin Film Silicon: Synergy between Displays and Solar Cells

    NARCIS (Netherlands)

    Schropp, R.E.I.

    2012-01-01

    Thin-film silicon technology has changed our society, owing to the rapid advance of its two major application fields in communication (thin-film displays) and sustainable energy (thin-film solar cells). Throughout its development, advances in these application fields have always benefitted each othe

  8. Effects of electrolyte gating on photoluminescence spectra of large-area WSe2monolayer films

    KAUST Repository

    Matsuki, Keiichiro

    2016-05-24

    We fabricated electric double-layer transistors comprising large-area WSe2 monolayers and investigated the effects of electrolyte gating on their photoluminescence (PL) spectra. Using the efficient gating effects of electric double layers, we succeeded in the application of a large electric field (>107Vcm%1) and the accumulation of high carrier density (>1013cm%2). As a result, we observed PL spectra based on both positively and negatively charged excitons and their gate-voltage-dependent redshifts, suggesting the effects of both an electric field and charge accumulation. © 2016 The Japan Society of Applied Physics.

  9. Large area polysilicon films with predetermined stress characteristics and method for producing same

    Science.gov (United States)

    Heuer, Arthur H. (Inventor); Kahn, Harold (Inventor); Yang, Jie (Inventor); Phillips, Stephen M. (Inventor)

    2002-01-01

    Multi-layer assemblies of polysilicon thin films having predetermined stress characteristics and techniques for forming such assemblies are disclosed. In particular, a multi-layer assembly of polysilicon thin films may be produced that has a stress level of zero, or substantially so. The multi-layer assemblies comprise at least one constituent thin film having a tensile stress and at least one constituent thin film having a compressive stress. The thin films forming the multi-layer assemblies may be disposed immediately adjacent to one another without the use of intermediate layers between the thin films. Multi-layer assemblies exhibiting selectively determinable overall bending moments are also disclosed. Selective production of overall bending moments in microstructures enables manufacture of such structures with a wide array of geometrical configurations.

  10. Pulsed Laser Deposition of Er doped tellurite films on large area

    Energy Technology Data Exchange (ETDEWEB)

    Bouazaoui, M [Laboratoire PhLAM, UMR 8523, Groupe Photonique, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq Cedex (France); Capoen, B [Laboratoire PhLAM, UMR 8523, Groupe Photonique, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq Cedex (France); Caricato, A P [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Chiasera, A [CNR-IFN, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Fazzi, A [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Ferrari, M [CNR-IFN, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Leggieri, G [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Martino, M [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Mattarelli, M [Physics Department, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Montagna, M [Physics Department, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Romano, F [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Tunno, T [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Turrel, S [Universite des Sciences et Technologies de Lille, Laboratoire de Spectrochimie Infrarouge et Raman, LASIR - UMR 8516 du CNRS - Bat C5 - 59655 - Villeneuve d' Ascq cedex (France); Vishnubhatla, K [Physics Department, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy)

    2007-04-15

    Thin films of Er{sup 3+}-doped tungsten tellurite glass have been prepared by the pulsed laser deposition technique using an ArF excimer laser. The depositions were performed at different O{sub 2} pressure (5, 10 Pa) and at different substrate temperatures (RT, 100deg. C and 200deg. C). The composition and the optical properties of the deposited films, such as transmission, dispersion curves of refraction index and extinction coefficient, and film thickness were studied for the different deposition parameters. Transparent films at the highest substrate temperature were obtained only for a higher oxygen pressure with respect to the RT conditions.

  11. Controlled-layer and large-area MoSsub>2sub> films encapsulated Au nanoparticle hybrids for SERS.

    Science.gov (United States)

    Li, Zhen; Jiang, Shouzhen; Huo, Yanyan; Liu, Mei; Yang, Cheng; Zhang, Chao; Liu, Xiaoyun; Sheng, Yingqing; Li, Chonghui; Man, Baoyuan

    2016-11-14

    In this work, a facile and effective method for controlled-layer and large-area MoSsub>2sub> films encapsulated Au nanoparticle hybrids is developed. With accurate Ar plasma treatment time control, the large-area MoSsub>2sub> layers can be obtained from monolayer to trilayer. The fabricated MoSsub>2sub>@Au NPs with higher surface area exhibit excellent Raman enhanced effect for aromatic organic molecules (rhodamine 6G and crystal violet) and achieve the best when the monolayer MoSsub>2sub>@AuNPs was obtained. The limit of detection is found to be as low as 1 × 10-10 M. The MoSsub>2sub>@AuNPs was characterized by SEM, EDS, AFM, Raman spectroscopy, UV-Vis, XRD and HRTEM.

  12. Large-Area Dry Transfer of Single-Crystalline Epitaxial Bismuth Thin Films.

    Science.gov (United States)

    Walker, Emily S; Na, Seung Ryul; Jung, Daehwan; March, Stephen D; Kim, Joon-Seok; Trivedi, Tanuj; Li, Wei; Tao, Li; Lee, Minjoo L; Liechti, Kenneth M; Akinwande, Deji; Bank, Seth R

    2016-11-09

    We report the first direct dry transfer of a single-crystalline thin film grown by molecular beam epitaxy. A double cantilever beam fracture technique was used to transfer epitaxial bismuth thin films grown on silicon (111) to silicon strips coated with epoxy. The transferred bismuth films retained electrical, optical, and structural properties comparable to the as-grown epitaxial films. Additionally, we isolated the bismuth thin films on freestanding flexible cured-epoxy post-transfer. The adhesion energy at the bismuth/silicon interface was measured to be ∼1 J/m(2), comparable to that of exfoliated and wet transferred graphene. This low adhesion energy and ease of transfer is unexpected for an epitaxially grown film and may enable the study of bismuth's unique electronic and spintronic properties on arbitrary substrates. Moreover, this method suggests a route to integrate other group-V epitaxial films (i.e., phosphorus) with arbitrary substrates, as well as potentially to isolate bismuthene, the atomic thin-film limit of bismuth.

  13. A direct thin-film path towards low-cost large-area III-V photovoltaics.

    Science.gov (United States)

    Kapadia, Rehan; Yu, Zhibin; Wang, Hsin-Hua H; Zheng, Maxwell; Battaglia, Corsin; Hettick, Mark; Kiriya, Daisuke; Takei, Kuniharu; Lobaccaro, Peter; Beeman, Jeffrey W; Ager, Joel W; Maboudian, Roya; Chrzan, Daryl C; Javey, Ali

    2013-01-01

    III-V photovoltaics (PVs) have demonstrated the highest power conversion efficiencies for both single- and multi-junction cells. However, expensive epitaxial growth substrates, low precursor utilization rates, long growth times, and large equipment investments restrict applications to concentrated and space photovoltaics (PVs). Here, we demonstrate the first vapor-liquid-solid (VLS) growth of high-quality III-V thin-films on metal foils as a promising platform for large-area terrestrial PVs overcoming the above obstacles. We demonstrate 1-3 μm thick InP thin-films on Mo foils with ultra-large grain size up to 100 μm, which is ~100 times larger than those obtained by conventional growth processes. The films exhibit electron mobilities as high as 500 cm²/V-s and minority carrier lifetimes as long as 2.5 ns. Furthermore, under 1-sun equivalent illumination, photoluminescence efficiency measurements indicate that an open circuit voltage of up to 930 mV can be achieved, only 40 mV lower than measured on a single crystal reference wafer.

  14. Large-area, Lithography-Free Super Absorbers and Color Filters at Visible Frequencies Using Ultrathin Metallic Films

    CERN Document Server

    Li, Zhongyang; Aydin, Koray

    2014-01-01

    Plasmonic materials and metamaterials have been widely utilized to achieve spectral transmission, reflection and absorption filters based on localized or delocalized resonances arising from the interaction of photons with nanostructured materials. Realization of visible-frequency, high-performance, large-area, optical filters based on nanoplasmonic materials is rather challenging due to nanofabrication related problems (cost, fabrication imperfection, surface roughness) and optical losses of metals. Here, we propose and demonstrate large-area perfect absorbers and transmission filters that overcome difficulties associated with the nanofabrication using a lithography-free approach. We also utilize and benefit from the optical losses in metals in our optical filter designs. Our resonant optical filter design is based on a modified, asymmetric metal-insulator-metal (MIM) based Fabry-Perot cavity with plasmonic, lossy ultra-thin (~30 nm) metallic films used as the top metallic layer. We demonstrated a narrow band...

  15. Imposed quasi-layer-by-layer homoepitaxial growth of SrTiO3 films by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Pryds, Nini

    2011-01-01

    The homoepitaxial growth of SrTiO3 (STO) films was investigated by a large-area pulsed laser deposition (PLD), which was in-situ monitored by a high pressure reflective high energy electron diffraction. By combining a conventionally continuous film deposition with a followed interval relaxation, ...

  16. Polymer blend lithography for metal films: large-area patterning with over 1 billion holes/inch2

    Directory of Open Access Journals (Sweden)

    Cheng Huang

    2015-05-01

    Full Text Available Polymer blend lithography (PBL is a spin-coating-based technique that makes use of the purely lateral phase separation between two immiscible polymers to fabricate large area nanoscale patterns. In our earlier work (Huang et al. 2012, PBL was demonstrated for the fabrication of patterned self-assembled monolayers. Here, we report a new method based on the technique of polymer blend lithography that allows for the fabrication of metal island arrays or perforated metal films on the nanometer scale, the metal PBL. As the polymer blend system in this work, a mixture of polystyrene (PS and poly(methyl methacrylate (PMMA, dissolved in methyl ethyl ketone (MEK is used. This system forms a purely lateral structure on the substrate at controlled humidity, which means that PS droplets are formed in a PMMA matrix, whereby both phases have direct contact both to the substrate and to the air interface. Therefore, a subsequent selective dissolution of either the PS or PMMA component leaves behind a nanostructured film which can be used as a lithographic mask. We use this lithographic mask for the fabrication of metal patterns by thermal evaporation of the metal, followed by a lift-off process. As a consequence, the resulting metal nanostructure is an exact replica of the pattern of the selectively removed polymer (either a perforated metal film or metal islands. The minimum diameter of these holes or metal islands demonstrated here is about 50 nm. Au, Pd, Cu, Cr and Al templates were fabricated in this work by metal PBL. The wavelength-selective optical transmission spectra due to the localized surface plasmonic effect of the holes in perforated Al films were investigated and compared to the respective hole diameter histograms.

  17. Polymer blend lithography for metal films: large-area patterning with over 1 billion holes/inch(2).

    Science.gov (United States)

    Huang, Cheng; Förste, Alexander; Walheim, Stefan; Schimmel, Thomas

    2015-01-01

    Polymer blend lithography (PBL) is a spin-coating-based technique that makes use of the purely lateral phase separation between two immiscible polymers to fabricate large area nanoscale patterns. In our earlier work (Huang et al. 2012), PBL was demonstrated for the fabrication of patterned self-assembled monolayers. Here, we report a new method based on the technique of polymer blend lithography that allows for the fabrication of metal island arrays or perforated metal films on the nanometer scale, the metal PBL. As the polymer blend system in this work, a mixture of polystyrene (PS) and poly(methyl methacrylate) (PMMA), dissolved in methyl ethyl ketone (MEK) is used. This system forms a purely lateral structure on the substrate at controlled humidity, which means that PS droplets are formed in a PMMA matrix, whereby both phases have direct contact both to the substrate and to the air interface. Therefore, a subsequent selective dissolution of either the PS or PMMA component leaves behind a nanostructured film which can be used as a lithographic mask. We use this lithographic mask for the fabrication of metal patterns by thermal evaporation of the metal, followed by a lift-off process. As a consequence, the resulting metal nanostructure is an exact replica of the pattern of the selectively removed polymer (either a perforated metal film or metal islands). The minimum diameter of these holes or metal islands demonstrated here is about 50 nm. Au, Pd, Cu, Cr and Al templates were fabricated in this work by metal PBL. The wavelength-selective optical transmission spectra due to the localized surface plasmonic effect of the holes in perforated Al films were investigated and compared to the respective hole diameter histograms.

  18. Large area polycrystalline diamond films as high current photocathodes for linear induction accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, R.P.; Moir, D.C.; Devlin, D.J.; Springer, R.W.

    1997-08-01

    Investigations are underway at Los Alamos to develop a new generation of high current, low source temperature photo cathodes able to operate in vacuum environments with pressures above 10e-6 torr without poisoning or degradation of emission properties. Polycrystalline diamond films are emerging as the ideal material for these photocathodes. Robustness, high quantum efficiency and high thermal conductivity are fundamental necessary attributes that are found in diamond. The high electron/hole mobility in the boron doped diamond lattice and the ability to create a negative electron affinity surface through downward band bending allow for high current density emission with quantum efficiencies of 0.5% when illuminated by a ArF laser. We report the results to date toward the development of a four kiloampere photocathode with a source temperature below 5eV for the DARHT linear induction Accelerator

  19. Large-Area Nanoparticle Films by Continuous Automated Langmuir-Blodgett Assembly and Deposition.

    Science.gov (United States)

    Li, Xue; Gilchrist, James F

    2016-02-09

    The operating parameters and resulting surface morphology of automated Langmuir-Blodgett deposition of monosized micrometer-scale silica colloids from an aqueous suspension are investigated. This apparatus allows continuous roll-to-roll deposition of particles into well-ordered arrays. The reproducible deposition of particle monolayers at low to moderate deposition rates at web speeds of less than 10 mm/s is possible and accurately characterized by a simple mass balance of particles deposited from solution. At faster deposition rates, Landau-Levich flow increases the film thickness such that flow instabilities hinder uniform particle deposition. A simple phase diagram outlines transitions from dispersed to multilayer coatings and from uniform to erratic deposition patterns. While the threshold of maximum deposition rate is well-defined for these conditions, changing operating parameters, particle size, and fluid viscosity and evaporation rate, the maximum speed can be increased significantly.

  20. Vapor and healing treatment for CH3NH3PbI(3-x)Cl(x) films toward large-area perovskite solar cells.

    Science.gov (United States)

    Gouda, Laxman; Gottesman, Ronen; Tirosh, Shay; Haltzi, Eynav; Hu, Jiangang; Ginsburg, Adam; Keller, David A; Bouhadana, Yaniv; Zaban, Arie

    2016-03-28

    Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm(2)). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (V(oc), J(sc), Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ∼100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a "healing effect" to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method.

  1. A novel synthesis method for large-area MoS2 film with improved electrical contact

    Science.gov (United States)

    Song, Xiongfei; Zan, Wu; Xu, Hu; Ding, Shijin; Zhou, Peng; Bao, Wenzhong; Zhang, David Wei

    2017-06-01

    Two-dimensional layered materials (2DLMs) are radically different from conventional bulk semiconductors, and major challenges in achieving practical 2DLM devices with good performance lie in the areas of improving the electrical contacts that connect 2DLMS with electrodes rather than in improving the quality of the channel material itself. To meet this challenge, we have devised a promising large-scale synthesis method for few-layer MoS2 film integrated with unique fabrication process that provides good contact. A thin layer of Mo was first deposited using sputtering evaporation and defined by a shadow mask, instead of immediate sulfurization in a chemical vapor deposition (CVD) furnace. Au contact electrodes were then deposited on Mo, followed by further sulfurization, which readily provides source-drain electrodes for synthesized MoS2. Top-gated transistors based on such MoS2 film show improved device performance compared to transistors fabricated using the traditional method. The transfer line method was further applied to verify that the proposed method could effectively decrease the contact resistance by more than 10 times, which can be attributed to the incomplete sulfurization of Mo atoms beneath the Au electrodes. It is envisioned that the proposed method could eventually be used to provide uniform and low contact resistance for CVD-grown 2DLM devices.

  2. One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films

    KAUST Repository

    Giri, Gaurav

    2014-04-16

    A crystal\\'s structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes. © 2014 Macmillan Publishers Limited.

  3. Large-area homogeneous periodic surface structures generated on the surface of sputtered boron carbide thin films by femtosecond laser processing

    Energy Technology Data Exchange (ETDEWEB)

    Serra, R., E-mail: ricardo.serra@dem.uc.pt [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra (Portugal); Oliveira, V. [ICEMS-Instituto de Ciência e Engenharia de Materiais e Superfícies, Avenida Rovisco Pais no 1, 1049-001 Lisbon (Portugal); Instituto Superior de Engenharia de Lisboa, Avenida Conselheiro Emídio Navarro no 1, 1959-007 Lisbon (Portugal); Oliveira, J.C. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra (Portugal); Kubart, T. [The Ångström Laboratory, Solid State Electronics, P.O. Box 534, SE-751 21 Uppsala (Sweden); Vilar, R. [Instituto Superior de Engenharia de Lisboa, Avenida Conselheiro Emídio Navarro no 1, 1959-007 Lisbon (Portugal); Instituto Superior Técnico, Avenida Rovisco Pais no 1, 1049-001 Lisbon (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra (Portugal)

    2015-03-15

    Highlights: • Large-area LIPSS were formed by femtosecond laser processing B-C films surface. • The LIPSS spatial period increases with laser fluence (140–200 nm). • Stress-related sinusoidal-like undulations were formed on the B-C films surface. • The undulations amplitude (down to a few nanometres) increases with laser fluence. • Laser radiation absorption increases with surface roughness. - Abstract: Amorphous and crystalline sputtered boron carbide thin films have a very high hardness even surpassing that of bulk crystalline boron carbide (≈41 GPa). However, magnetron sputtered B-C films have high friction coefficients (C.o.F) which limit their industrial application. Nanopatterning of materials surfaces has been proposed as a solution to decrease the C.o.F. The contact area of the nanopatterned surfaces is decreased due to the nanometre size of the asperities which results in a significant reduction of adhesion and friction. In the present work, the surface of amorphous and polycrystalline B-C thin films deposited by magnetron sputtering was nanopatterned using infrared femtosecond laser radiation. Successive parallel laser tracks 10 μm apart were overlapped in order to obtain a processed area of about 3 mm{sup 2}. Sinusoidal-like undulations with the same spatial period as the laser tracks were formed on the surface of the amorphous boron carbide films after laser processing. The undulations amplitude increases with increasing laser fluence. The formation of undulations with a 10 μm period was also observed on the surface of the crystalline boron carbide film processed with a pulse energy of 72 μJ. The amplitude of the undulations is about 10 times higher than in the amorphous films processed at the same pulse energy due to the higher roughness of the films and consequent increase in laser radiation absorption. LIPSS formation on the surface of the films was achieved for the three B-C films under study. However, LIPSS are formed under

  4. The large-area CdTe thin film for CdS/CdTe solar cell prepared by physical vapor deposition in medium pressure

    Science.gov (United States)

    Luo, Run; Liu, Bo; Yang, Xiaoyan; Bao, Zheng; Li, Bing; Zhang, Jingquan; Li, Wei; Wu, Lili; Feng, Lianghuan

    2016-01-01

    The Cadmium telluride (CdTe) thin film has been prepared by physical vapor deposition (PVD), the Ar + O2 pressure is about 0.9 kPa. This method is a newer technique to deposit CdTe thin film in large area, and the size of the film is 30 × 40 cm2. This method is much different from the close-spaced sublimation (CSS), as the relevance between the source temperature and the substrate temperature is weak, and the gas phase of CdTe is transferred to the substrate by Ar + O2 flow. Through this method, the compact and uniform CdTe film (30 × 40 cm2) has been achieved, and the performances of the CdTe thin film have been determined by transmission spectrum, SEM and XRD. The film is observed to be compact with a good crystallinity, the CdTe is polycrystalline with a cubic structure and a strongly preferred (1 1 1) orientation. Using the CdTe thin film (3 × 5 cm2) which is taken from the deposited large-area film, the 14.6% efficiency CdS/CdTe thin film solar cell has been prepared successfully. The structure of the cell is glass/FTO/CdS/CdTe/graphite slurry/Au, short circuit current density (Jsc) of the cell is 26.9 mA/cm2, open circuit voltage (Voc) is 823 mV, and filling factor (FF) is 66.05%. This technique can be a quite promising method to apply in the industrial production, as it has great prospects in the fabricating of large-area CdTe film.

  5. Dynamic-template-directed multiscale assembly for large-area coating of highly-aligned conjugated polymer thin films

    Science.gov (United States)

    Mohammadi, Erfan; Zhao, Chuankai; Meng, Yifei; Qu, Ge; Zhang, Fengjiao; Zhao, Xikang; Mei, Jianguo; Zuo, Jian-Min; Shukla, Diwakar; Diao, Ying

    2017-07-01

    Solution processable semiconducting polymers have been under intense investigations due to their diverse applications from printed electronics to biomedical devices. However, controlling the macromolecular assembly across length scales during solution coating remains a key challenge, largely due to the disparity in timescales of polymer assembly and high-throughput printing/coating. Herein we propose the concept of dynamic templating to expedite polymer nucleation and the ensuing assembly process, inspired by biomineralization templates capable of surface reconfiguration. Molecular dynamic simulations reveal that surface reconfigurability is key to promoting template-polymer interactions, thereby lowering polymer nucleation barrier. Employing ionic-liquid-based dynamic template during meniscus-guided coating results in highly aligned, highly crystalline donor-acceptor polymer thin films over large area (>1 cm2) and promoted charge transport along both the polymer backbone and the π-π stacking direction in field-effect transistors. We further demonstrate that the charge transport anisotropy can be reversed by tuning the degree of polymer backbone alignment.

  6. Crystal Structure and Optical Properties of Al-Doped ZnO Large-Area Thin Films Using 1500 mm Dual Cylindrical Cathodes.

    Science.gov (United States)

    Lee, JinJu; Ha, Jong-Yoon; Yim, Haena; Choi, Won-Kook; Choi, Ji-Won

    2015-11-01

    The large-area Al-doped ZnO thin films are successfully deposited at room temperature on polycarbonate substrate using a 1500 mm dual cylindrical cathodes sputtering system. Those thin films have smooth surfaces (RMS: 9.6 nm) and lower thicknesses deviation (Uniformity: 98.6%) despite of high RF power. The optical transmittance properties of 3.13 wt% Al doped ZnO thin films have above 85% in visible region. A dual cylindrical cathodes sputtering system can fabricate transparent electrode on flexible electronic devices at room temperature for mass production of 6th generation solar cell and display industry.

  7. Vapor and healing treatment for CH3NH3PbI3-xClx films toward large-area perovskite solar cells

    Science.gov (United States)

    Gouda, Laxman; Gottesman, Ronen; Tirosh, Shay; Haltzi, Eynav; Hu, Jiangang; Ginsburg, Adam; Keller, David A.; Bouhadana, Yaniv; Zaban, Arie

    2016-03-01

    Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non-uniform performance. Thus, production and characterization of the lateral uniformity of large-area films is a crucial step towards scale-up of devices. In this paper, we present a reproducible method for improving the lateral uniformity and performance of large-area perovskite solar cells (32 cm2). The method is based on methyl-ammonium iodide (MAI) vapor treatment as a new step in the sequential deposition of perovskite films. Following the MAI vapor treatment, we used high throughput techniques to map the photovoltaic performance throughout the large-area device. The lateral uniformity and performance of all photovoltaic parameters (Voc, Jsc, Fill Factor, Photo-conversion efficiency) increased, with an overall improved photo-conversion efficiency of ~100% following a vapor treatment at 140 °C. Based on XRD and photoluminescence measurements, We propose that the MAI treatment promotes a ``healing effect'' to the perovskite film which increases the lateral uniformity across the large-area solar cell. Thus, the straightforward MAI vapor treatment is highly beneficial for large scale commercialization of perovskite solar cells, regardless of the specific deposition method.Hybrid methyl-ammonium lead trihalide perovskites are promising low-cost materials for use in solar cells and other optoelectronic applications. With a certified photovoltaic conversion efficiency record of 20.1%, scale-up for commercial purposes is already underway. However, preparation of large-area perovskite films remains a challenge, and films of perovskites on large electrodes suffer from non

  8. Preparation of born-doped a-SiC:H thin films by ICP-CVD method and to the application of large-area heterojunction solar cells.

    Science.gov (United States)

    Jeong, Chaehwan; Kim, Young-Back; Lee, Suk-Ho; Kim, Jin Hyeok

    2010-05-01

    Hydrogenated amorphous silicon carbide (a-SiC:H) film has been widely used as an emitter p layer in solar cells. For the better p layer, wide optical bandgap, and high electrical conductivity should be obtained from the effective method. We prepared the boron-doped a-SiC:H thin films using inductively coupled plasma chemical vapor deposition (ICP-CVD) method and characteristics on the small-area (2 cm x 2 cm) as well as the large-area films (diameter of 100 mm) were shown on it. As a substrate, the n-type (100) oriented CZ c-Si (5.5 approximately 6.5 omega x cm, 650 microm) wafers were used and cleaned by using the reduced RCA method. A silane (SiH4) of 99.999% purity, H2 and 60% hydrogen diluted ethylene (C2H4) was used as source gas for the deposition of intrinsic a-SiC:H films, and then diborane (B2H6), as the doping gas, is added to C2H4 and SiH4/H2 during the deposition of films. The uniformity of thickness and optical bandgap from large-area as-dep. films was at 1.8% and 0.3%, respectively. Heterojunction solar cell with 2 wt%-AZO/p-a-SiC:H/i-a-Si:H/c-Si/Ag structure was fabricated and characterized with diameter of 152.3 mm in this large-area ICP-CVD system. Conversion efficiency of 9.123% was achieved with a practical area of 100 mm x 100 mm, which can show the potentials to the fabrication of the large-area solar cell using ICP-CVD method.

  9. Wrinkle-free graphene electrodes in zinc tin oxide thin-film transistors for large area applications

    Science.gov (United States)

    Lee, Se-Hee; Kim, Jae-Hee; Park, Byeong-Ju; Park, Jozeph; Kim, Hyun-Suk; Yoon, Soon-Gil

    2017-02-01

    Wrinkle-free graphene was used to form the source-drain electrodes in thin film transistors based on a zinc tin oxide (ZTO) semiconductor. A 10 nm thick titanium adhesion layer was applied prior to transferring a conductive graphene film on top of it by chemical detachment. The formation of an interlayer oxide between titanium and graphene allows the achievement of uniform surface roughness over the entire substrate area. The resulting devices were thermally treated in ambient air, and a substantial decrease in field effect mobility is observed with increasing annealing temperature. The increase in electrical resistivity of the graphene film at higher annealing temperatures may have some influence, however the growth of the oxide interlayer at the ZTO/Ti boundary is suggested to be most influential, thereby inducing relatively high contact resistance.

  10. Large-area homogeneous periodic surface structures generated on the surface of sputtered boron carbide thin films by femtosecond laser processing

    Science.gov (United States)

    Serra, R.; Oliveira, V.; Oliveira, J. C.; Kubart, T.; Vilar, R.; Cavaleiro, A.

    2015-03-01

    Amorphous and crystalline sputtered boron carbide thin films have a very high hardness even surpassing that of bulk crystalline boron carbide (≈41 GPa). However, magnetron sputtered B-C films have high friction coefficients (C.o.F) which limit their industrial application. Nanopatterning of materials surfaces has been proposed as a solution to decrease the C.o.F. The contact area of the nanopatterned surfaces is decreased due to the nanometre size of the asperities which results in a significant reduction of adhesion and friction. In the present work, the surface of amorphous and polycrystalline B-C thin films deposited by magnetron sputtering was nanopatterned using infrared femtosecond laser radiation. Successive parallel laser tracks 10 μm apart were overlapped in order to obtain a processed area of about 3 mm2. Sinusoidal-like undulations with the same spatial period as the laser tracks were formed on the surface of the amorphous boron carbide films after laser processing. The undulations amplitude increases with increasing laser fluence. The formation of undulations with a 10 μm period was also observed on the surface of the crystalline boron carbide film processed with a pulse energy of 72 μJ. The amplitude of the undulations is about 10 times higher than in the amorphous films processed at the same pulse energy due to the higher roughness of the films and consequent increase in laser radiation absorption. LIPSS formation on the surface of the films was achieved for the three B-C films under study. However, LIPSS are formed under different circumstances. Processing of the amorphous films at low fluence (72 μJ) results in LIPSS formation only on localized spots on the film surface. LIPSS formation was also observed on the top of the undulations formed after laser processing with 78 μJ of the amorphous film deposited at 800 °C. Finally, large-area homogeneous LIPSS coverage of the boron carbide crystalline films surface was achieved within a large range

  11. Optimization of large area YBa sub 2 Cu sub 3 O sub 7-x films by single target ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Gauzzi, A.; Lucia, M.L.; Affronte, M.; Pavuna, D. (Inst. for Micro- and Optoelectronics, Swiss Federal Inst. of Tech. (EPFL), Lausanne (Switzerland))

    1991-12-01

    We report on the in-situ growth over large area of high-quality homogeneous YBa{sub 2}Cu{sub 3}O{sub 7-x} films by single target ion beam sputtering. The '123' stoichiometry transfer to the substrates is obtained by using sufficiently low power ion beam and a grazing angle between the ion beam and the target. The as-deposited films show consistent homogeneity and reproducible superconducting properties ({Delta}Tc<1 K, j{sub c}(77K)>10{sup 6} A cm{sup -2} at 77K) over areas larger than {approx equal}30 cm{sup 2}. (orig.).

  12. Emerging photoluminescence from bilayer large-area 2D MoS2 films grown by pulsed laser deposition on different substrates

    Science.gov (United States)

    Barvat, Arun; Prakash, Nisha; Satpati, Biswarup; Singha, Shib Shankar; Kumar, Gaurav; Singh, Dilip K.; Dogra, Anjana; Khanna, Suraj P.; Singha, Achintya; Pal, Prabir

    2017-07-01

    We report the growth of continuous large area bilayer films of MoS2 on different substrates by pulsed laser deposition (PLD). The growth parameters for PLD were modified in such a way that results in bilayer 2D-MoS2 films on both c-Al2O3 (0001) (sapphire) and SiO2/Si (SO) substrates. The bilayer large area crystalline nature of growth in the 2 H-phase is determined by Raman spectroscopy. Cross-sectional transmission electron microscopy confirms the distinct thinnest ordered layered structure of MoS2. Chemical analysis reveals an almost stoichiometric 2 H-phase on both the substrates. The photoluminescence intensities of both the films match very well with those of the corresponding exfoliated flakes, as well as chemical vapor deposited (CVD) films as reported in the literature. The in-situ post growth annealing with optimal film thickness acts as a solid phase epitaxy process which provides continuous crystalline layers with a smooth interface and regulates the photoluminescence properties. In contrast, the PLD grown MoS2 monolayer shows poor crystalline quality and non-uniform coverage compared to that with the exfoliated and CVD grown films.

  13. High-Mobility Transistors Based on Large-Area and Highly Crystalline CVD-Grown MoSe2 Films on Insulating Substrates.

    Science.gov (United States)

    Rhyee, Jong-Soo; Kwon, Junyeon; Dak, Piyush; Kim, Jin Hee; Kim, Seung Min; Park, Jozeph; Hong, Young Ki; Song, Won Geun; Omkaram, Inturu; Alam, Muhammad A; Kim, Sunkook

    2016-03-23

    Large-area and highly crystalline CVD-grown multilayer MoSe2 films exhibit a well-defined crystal structure (2H phase) and large grains reaching several hundred micrometers. Multilayer MoSe2 transistors exhibit high mobility up to 121 cm(2) V(-1) s(-1) and excellent mechanical stability. These results suggest that high mobility materials will be indispensable for various future applications such as high-resolution displays and human-centric soft electronics.

  14. Large area superconducting YBa 2Cu 3O 7-x films grown by single target ion beam sputtering

    Science.gov (United States)

    Gauzzi, Andrea; Lucía, Maria L.; Kellett, Bruce J.; James, Jonathan H.; Pavuna, Davor

    1991-10-01

    We have demonstrated, by using a simple single YBa 2Cu 3O 7- x target ion beam system that, with a sufficiently low power ion beam, preferential sputtering is avoided and high-quality YBa 2Cu 3O 7- x films are deposited over areas larger than ≈ 30 cm 2 in a reproducible way. As-deposited films on SrTiO 3 are 50-100 nmthick, c-oriented and show the following reproducible electrical properties (within the given variations): Tc0 =90±0.5 K, transitions widths less than 1 K, j inc(77 K)=1.0-1.2× 10 6 A cm -2, ϱ(300 K)=300±50μΩ cm, ϱ(300 K)/ ϱ(100 K)=2.9±0.1. The extrapolated residual resistivity ϱ res(O K) is between 0 and 5% of ϱ(300 K).

  15. Large-area atomic layer deposition and characterization of Al sub 2 O sub 3 film grown using AlCl sub 3 and H sub 2 O

    CERN Document Server

    Yun, S J; Paek, M C; Nam, K S

    1998-01-01

    The atomic layer deposition (ALD) process of Al sub 2 O sub 3 films in a large area traveling wave reactor was studied as well as the materials and electrical characteristics of the films. The precursors used in the deposition of Al sub 2 O sub 3 were AlCl sub 3 and H sub 2 O. The dependence of growth rate and Cl content of Al sub 2 O sub 3 films on the growth temperature was investigated at the reactor temperature ranging from 300 .deg. C to 500 .deg. C. The growth rate decreased from 0.66 to 0.45 A/cycle as the reactor temperature increased from 330 .deg. C to 500 .deg. C. The etch rate of the films and the annealing effect on the crystallinity of Al sub 2 O sub 3 films were also studied. The dependence of characteristics of Al sub 2 O sub 3 on the growth conditions was discussed according to the growth mechanism. The electrical characteristics including breakdown electric field and leakage current of the Al sub 2 O sub 3 films were measured to determine the effect of growth temperature on electrical proper...

  16. Note: Large area deposition of Rh single and Rh/W/Cu multilayer thin films on stainless steel substrate by pulsed laser deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Mostako, A. T. T.; Khare, Alika, E-mail: alika@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2014-04-15

    Mirror like thin films of single layer Rh and multilayer Rh/W/Cu are deposited on highly polished 50 mm diameter stainless steel substrate by Pulsed Laser Deposition (PLD) technique for first mirror application in fusion reactors. For this, the conventional PLD technique has been modified by incorporating substrate rastering stage for large area deposition via PLD. Process optimization to achieve uniformity of deposition as estimated from fringe visibility and thickness is also discussed.

  17. Boron doped diamond thin films on large area Ti6Al4V substrates for electrochemical application

    Directory of Open Access Journals (Sweden)

    Alessandra V. Diniz

    2003-01-01

    Full Text Available Boron doped diamond thin films were grown on titanium alloy substrates (Ti6Al4V with 36 × 35 × 1.3 mm at 873-933 K at 6.5 × 10³ Pa during 8 h by hot filament CVD assisted technique. The boron source was obtained from a H2 line forced to pass through a bubbler containing B2O3 dissolved in methanol (BC = 6000 ppm. The films were grown on both sides of perforated and non-perforated substrates. Emphasis for diamond growing on perforated substrates have been done in order to increase the active surface area and hereafter to promote an easier electrolyte flow for wastewater treatment. The electrode performance was determined by cyclic voltammetry measurements in KCl, KNO3, Na2SO4, HCl, HNO3 and H2SO4 solutions and the reversibility behavior of the Fe(CN6(3-/4- at the Ti6Al4V/Diamond electrode were studied. Also, Scaning Electron Microcopy and Raman Scattering Spectroscopy were used for morphology and diamond quality evaluation, respectively.

  18. Large area LED package

    Science.gov (United States)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  19. Characterization of HgCdTe Films Grown on Large-Area CdZnTe Substrates by Molecular Beam Epitaxy

    Science.gov (United States)

    Arkun, F. Erdem; Edwall, Dennis D.; Ellsworth, Jon; Douglas, Sheri; Zandian, Majid; Carmody, Michael

    2017-09-01

    Recent advances in growth of Hg1- x Cd x Te films on large-area (7 cm × 7.5 cm) CdZnTe (CZT) substrates is presented. Growth of Hg1- x Cd x Te with good uniformity on large-area wafers is achieved using a Riber 412 molecular beam epitaxy (MBE) tool designed for growth of Hg1- x Cd x Te compounds. The reactor is equipped with conventional CdTe, Te, and Hg sources for achieving uniform exposure of the wafer during growth. The composition of the Hg1- x Cd x Te compound is controlled in situ by employing a closed-loop spectral ellipsometry technique to achieve a cutoff wavelength ( λ co) of 14 μm at 78 K. We present data on the thickness and composition uniformity of films grown for large-format focal-plane array applications. The composition and thickness nonuniformity are determined to be maps show the spatial distribution of defects generated during the epitaxial growth of the Hg1- x Cd x Te films. Microdefect densities are in the low 103 cm-2 range, and void defects are below 500 cm-2. Dislocation densities less than 5 × 105 cm-2 are routinely achieved for Hg1- x Cd x Te films grown on CZT substrates. HgCdTe 4k × 4k focal-plane arrays with 15 μm pitch for astronomical wide-area infrared imagers have been produced using the recently developed MBE growth process at Teledyne Imaging Sensors.

  20. Large area mass analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Rachev, Mikhail [Max-Planck-Institut for Nuclear Physics, Heidelberg Saupfercheckweg 1, Heidelberg 69117 (Germany)]. E-mail: mikhail.rachev@mpi-hd.mpg.de; Srama, Ralf [Max-Planck-Institut for Nuclear Physics, Heidelberg Saupfercheckweg 1, Heidelberg 69117 (Germany); Srowig, Andre [Max-Planck-Institut for Nuclear Physics, Heidelberg Saupfercheckweg 1, Heidelberg 69117 (Germany); Gruen, Eberhard [Max-Planck-Institut for Nuclear Physics, Heidelberg Saupfercheckweg 1, Heidelberg 69117 (Germany)

    2004-12-11

    A new time-of-flight spectrometer for the chemical analysis of cosmic dust particles in space has been simulated by Simion 7.0. The instrument is based upon impact ionization. This method is a reliable method for in situ dust detection and is well established. Instruments using the impact ionization flew on board of Helios and Galileo and are still in operation on board of the Ulysses and Cassini-Huygens missions. The new instrument has a large sensitive area of 0.1m2 in order to achieve a significant number of measurements. The mass resolution M/{delta}M>100 and the mass range covers the most relevant elements expected in cosmic dust. The instrument has a reflectron configuration which increases the mass resolution. Most of the ions released during the impact are focused to the detector. The ion detector consists of a large area ion-to-electron converter, an electron reflectron and a microchannel plate detector.

  1. Large area growth of monolayer MoS2 film on quartz and its use as a saturable absorber in laser mode-locking

    Science.gov (United States)

    Zhao, Wei-fang; Yu, Hua; Liao, Meng-zhou; Zhang, Ling; Zou, Shu-zhen; Yu, Hai-juan; He, Chao-jian; Zhang, Jing-yuan; Zhang, Guang-yu; Lin, Xue-chun

    2017-02-01

    Monolayer MoS2 film on quartz was fabricated by a home-made three-temperature zone chemical vapor deposition method. The photo, AFM image, Raman spectroscopy and HRTEM image showed that high quality as-grown MoS2 film completely covered the whole quartz substrate of a few cm2. A Nd:YVO4 laser with mode-locking operation was obtained by using the monolayer MoS2 on quartz as the saturable absorber (SA). To the best of our knowledge, this is the first report on large-area growth of high quality monolayer MoS2 film on transparent quartz substrate, and the first time that the CVD MoS2 SA was used in mode-locked solid state lasers. Because of the large area, high transmission, low non-saturable loss and high optical damage threshold of this material, it is very suitable for application in mode-locked solid state lasers.

  2. Intrinsic Doping in Electrodeposited ZnS Thin Films for Application in Large-Area Optoelectronic Devices

    Science.gov (United States)

    Madugu, Mohammad Lamido; Olusola, Olajide Ibukun-Olu; Echendu, Obi Kingsley; Kadem, Burak; Dharmadasa, Imyhamy Mudiy

    2016-06-01

    Zinc sulphide (ZnS) thin films with both n- and p-type electrical conductivity were grown on glass/fluorine-doped tin oxide-conducting substrates from acidic and aqueous solution containing ZnSO4 and (NH4)2S2O3 by simply changing the deposition potential in a two-electrode cell configuration. After deposition, the films were characterised using various analytical techniques. X-ray diffraction analysis reveals that the materials are amorphous even after heat treatment. Optical properties (transmittance, absorbance and optical bandgap) of the films were studied. The bandgaps of the films were found to be in the range (3.68-3.86) eV depending on the growth voltage. Photoelectrochemical cell measurements show both n- and p-type electrical conductivity for the films depending on the growth voltage. Scanning electron microscopy shows material clusters on the surface with no significant change after heat treatment at different temperatures. Atomic force microscopy shows that the surface roughness of these materials remain fairly constant reducing only from 18 nm to 17 nm after heat treatment. Thickness estimation of the films was also carried out using theoretical and experimental methods. Direct current conductivity measurements on both as-deposited and annealed films show that resistivity increased after heat treatment.

  3. A NOVEL LOW THERMAL BUDGET THIN-FILM POLYSILICON FABRICATION PROCESS FOR LARGE-AREA, HIGH-THROUGHPUT SOLAR CELL PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Yue Kuo

    2010-08-15

    A novel thin-film poly-Si fabrication process has been demonstrated. This low thermal budget process transforms the single- and multi-layer amorphous silicon thin films into a poly-Si structure in one simple step over a pulsed rapid thermal annealing process with the enhancement of an ultrathin Ni layer. The complete poly-Si solar cell was fabricated in a short period of time without deteriorating the underneath glass substrate. The unique vertical crystallization process including the mechanism is discussed. Influences of the dopant type and process parameters on crystal structure will be revealed. The poly-Si film structure has been proved using TEM, XRD, Raman, and XPS methods. The poly-Si solar cell structure and the performance have been examined. In principle, the new process is potentially applicable to produce large-area thin-film poly-Si solar cells at a high throughput and low cost. A critical issue in this process is to prevent the excessive dopant diffusion during crystallization. Process parameters and the cell structure have to be optimized to achieve the production goal.

  4. Investigation of the interfacial adhesion of the transparent conductive oxide films to large-area flexible polymer substrates using laser-induced thermo-mechanical stresses

    Science.gov (United States)

    Park, Jin-Woo; Lee, Seung-Ho; Yang, Chan-Woo

    2013-08-01

    In this study, we investigated the interfacial adhesion strength (σint) of transparent conductive oxide (TCO) coatings on polymer substrates using a nanosecond Nd:YAG pulsed laser. We compared our results with those achieved using conventional testing methods such as bending and fragmentation tests as well as theoretical calculations. In the fragmentation and bending tests, mechanical compressive stress is induced in the film due to mismatches in Poisson's ratio and Young's modulus between the substrate and film. But, the incident laser makes the film under compression due to the mismatch in thermal expansion between the TCO and the polymer substrate. With a pulse incident to the substrate, the TCO rapidly expands by laser-induced instant heating while the transparent polymer does little, which causes the TCO to buckle and delaminate over the critical pulse energy. The critical compressive stress that scales with σint was calculated using simple equations, which agreed well with the results from previous theoretical calculations. Because the films preferentially delaminate at the defects and grain boundaries, this technique also provided useful information regarding the interface microstructures. Moreover, because the laser can scan over large areas, this method is suitable for flexible substrates that are produced by a roll-to-roll process. Nevertheless, the mechanical stress introduced by the bending and fragmentation tests causes the TCO to buckle without interfacial delamination. Hence, the stresses at the buckling disagreed with the results obtained from the laser test and the theoretical calculations.

  5. Large-Area Growth of Uniform Single-Layer MoS2 Thin Films by Chemical Vapor Deposition.

    Science.gov (United States)

    Baek, Seung Hyun; Choi, Yura; Choi, Woong

    2015-12-01

    We report the largest-size thin films of uniform single-layer MoS2 on sapphire substrates grown by chemical vapor deposition based on the reaction of gaseous MoO3 and S evaporated from solid sources. The as-grown thin films of single-layer MoS2 were continuous and uniform in thickness for more than 4 cm without the existence of triangular-shaped MoS2 clusters. Compared to mechanically exfoliated crystals, the as-grown single-layer MoS2 thin films possessed consistent chemical valence states and crystal structure along with strong photoluminescence emission and optical absorbance at high energy. These results demonstrate that it is possible to scale up the growth of uniform single-layer MoS2 thin films, providing potentially important implications on realizing high-performance MoS2 devices.

  6. High-Rate Fabrication of a-Si-Based Thin-Film Solar Cells Using Large-Area VHF PECVD Processes

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xunming [University of Toledo; Fan, Qi Hua

    2011-12-31

    The University of Toledo (UT), working in concert with it’s a-Si-based PV industry partner Xunlight Corporation (Xunlight), has conducted a comprehensive study to develop a large-area (3ft x 3ft) VHF PECVD system for high rate uniform fabrication of silicon absorber layers, and the large-area VHF PECVD processes to achieve high performance a-Si/a-SiGe or a-Si/nc-Si tandem junction solar cells during the period of July 1, 2008 to Dec. 31, 2011, under DOE Award No. DE-FG36-08GO18073. The project had two primary goals: (i) to develop and improve a large area (3 ft × 3 ft) VHF PECVD system for high rate fabrication of > = 8 Å/s a-Si and >= 20 Å/s nc-Si or 4 Å/s a-SiGe absorber layers with high uniformity in film thicknesses and in material structures. (ii) to develop and optimize the large-area VHF PECVD processes to achieve high-performance a-Si/nc-Si or a-Si/a-SiGe tandem-junction solar cells with >= 10% stable efficiency. Our work has met the goals and is summarized in “Accomplishments versus goals and objectives”.

  7. Large area in situ fabrication of poly(pyrrole)-nanowires on flexible thermoplastic films using nanocontact printing

    Science.gov (United States)

    Garcia-Cruz, Alvaro; Lee, Michael; Marote, Pedro; Zine, Nadia; Sigaud, Monique; Bonhomme, Anne; Pruna, Raquel; Lopez, Manuel; Bausells, Joan; Jaffrezic, Nicole; Errachid, Abdelhamid

    2016-08-01

    Highly efficient nano-engineering tools will certainly revolutionize the biomedical and sensing devices research and development in the years to come. Here, we present a novel high performance conducting poly(pyrrole) nanowires (PPy-NW) patterning technology on thermoplastic surfaces (poly(ethylene terephthalate (PETE), poly(ethylene 2,6-naphthalate (PEN), polyimide (PI), and cyclic olefin copolymer) using nanocontact printing and controlled chemical polymerization (nCP-CCP) technique. The technique uses a commercial compact disk as a template to produce nanopatterned polydimethylsiloxane (PDMS) stamps. The PDMS nanopatterned stamp was applied to print the PPy-NWs and the developed technology of nCP-CCP produced 3D conducting nanostructures. This new and very promising nanopatterning technology was achieved in a single step and with a low cost of fabrication over large areas.

  8. Large area thin film CdTe and Zn(x)Cd(1-x)Te heterojunction solar cells

    Science.gov (United States)

    Chu, T. L.; Chu, S. S.; Firszt, F.; Naseem, H. A.; Stawski, R.

    Thin film CdTe heterojunction solar cells have been prepared by the deposition of p-type CdTe films on CdS/SnO2:F/glass substrates using chemical vapor deposition (CVD) and close-spaced sublimation (CSS) techniques. The relative merits of the two techniques are discussed, and the characteristics of solar cells prepared by CVD and CSS techniques are compared. In addition, the properties of Zn(x)Cd(1-x)Te have been investigated.

  9. Development of Tandem Amorphous/Microcrystalline Silicon Thin-Film Large-Area See-Through Color Solar Panels with Reflective Layer and 4-Step Laser Scribing for Building-Integrated Photovoltaic Applications

    National Research Council Canada - National Science Library

    Tsai, Chin-Yi; Tsai, Chin-Yao

    2014-01-01

      In this work, tandem amorphous/microcrystalline silicon thin-film large-area see-through color solar modules were successfully designed and developed for building-integrated photovoltaic applications...

  10. Development of electrical-erosion instrument for direct write micro-patterning on large area conductive thin films.

    Science.gov (United States)

    Álvarez, Ángel Luis; Coya, Carmen; García-Vélez, Miguel

    2015-08-01

    We have developed a complete instrument to perform direct, dry, and cost-effective lithography on conductive materials, based on localized electrical discharges, which avoids using masks or chemicals typical of conventional photolithography. The technique is considered fully compatible with substrate transport based systems, like roll-to-roll technology. The prototype is based on two piezo nano-steppers coupled to three linear micro-stages to cover a large scale operation from micrometers to centimeters. The operation mode consists of a spring probe biased at low DC voltage with respect to a grounded conductive layer. The tip slides on the target layer keeping contact with the material in room conditions, allowing continuous electric monitoring of the process, and also real-time tilt correction via software. The sliding tip leaves an insulating path (limited by the tip diameter) along the material, enabling to draw electrically insulated tracks and pads. The physical principle of operation is based in the natural self-limitation of the discharge due to material removal or insulation. The so produced electrical discharges are very fast, in the range of μs, so features may be performed at speeds of few cm/s, enabling scalability to large areas. The instrument has been tested on different conducting materials as gold, indium tin oxide, and aluminum, allowing the fabrication of alphanumeric displays based on passive matrix of organic light emitting diodes without the use of masks or photoresists. We have verified that the highest potential is achieved on graphene, where no waste material is detected, producing excellent well defined edges. This allows manufacturing graphene micro-ribbons with a high aspect ratio up to 1200:1.

  11. Development of electrical-erosion instrument for direct write micro-patterning on large area conductive thin films

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez, Ángel Luis; Coya, Carmen; García-Vélez, Miguel [Departamento Teoría de la Señal y Comunicaciones, Sistemas Telemáticos y Computación, Escuela Técnica Superior de Ingeniería de Telecomunicación, Universidad Rey Juan Carlos, Fuenlabrada, Madrid 28943 (Spain)

    2015-08-15

    We have developed a complete instrument to perform direct, dry, and cost-effective lithography on conductive materials, based on localized electrical discharges, which avoids using masks or chemicals typical of conventional photolithography. The technique is considered fully compatible with substrate transport based systems, like roll-to-roll technology. The prototype is based on two piezo nano-steppers coupled to three linear micro-stages to cover a large scale operation from micrometers to centimeters. The operation mode consists of a spring probe biased at low DC voltage with respect to a grounded conductive layer. The tip slides on the target layer keeping contact with the material in room conditions, allowing continuous electric monitoring of the process, and also real-time tilt correction via software. The sliding tip leaves an insulating path (limited by the tip diameter) along the material, enabling to draw electrically insulated tracks and pads. The physical principle of operation is based in the natural self-limitation of the discharge due to material removal or insulation. The so produced electrical discharges are very fast, in the range of μs, so features may be performed at speeds of few cm/s, enabling scalability to large areas. The instrument has been tested on different conducting materials as gold, indium tin oxide, and aluminum, allowing the fabrication of alphanumeric displays based on passive matrix of organic light emitting diodes without the use of masks or photoresists. We have verified that the highest potential is achieved on graphene, where no waste material is detected, producing excellent well defined edges. This allows manufacturing graphene micro-ribbons with a high aspect ratio up to 1200:1.

  12. A general method for growing large area mesoporous silica thin films on flat substrates with perpendicular nanochannels.

    Science.gov (United States)

    Kao, Kun-Che; Lin, Cheng-Han; Chen, Tzu-Ying; Liu, Yi-Hsin; Mou, Chung-Yuan

    2015-03-25

    Here we introduce a new synthetic approach to grow mesoporous silica thin films with vertical mesochannels on centimeter-sized substrates via an oil-induced co-assembly process. Adding an oil, i.e., decane, into a CTAB-EtOH-TEOS ammonia solution leads to thin-film formation of mesoporous silica of controlled thickness between 20 and 100 nm with vertical mesochannels on various surfaces. The vertical mesoporous channels were evidenced by grazing incidence small-angle X-ray scattering (GISAXS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) characterizations. Decane played two roles: (a) as a pore expansion agent (up to 5.7 ± 0.5 nm) and (b) inducing vertically oriented hexagonal mesophases of micelle-silica composite. The production of periodic and vertical nanochannels is very robust, over many different substrate surfaces (from silicon to polystyrene), various silica precursors (TEOS, fumed silica, or zeolite seed), and many oils (decane, petroleum ether, or ethyl acetate). This wide robustness in the formation of vertical nanophases is attributed to a unique mechanism of confined synthesis of surfactant-silicate between two identical thin layers of oils on a substrate.

  13. Large area perovskite solar cell module

    Science.gov (United States)

    Cai, Longhua; Liang, Lusheng; Wu, Jifeng; Ding, Bin; Gao, Lili; Fan, Bin

    2017-01-01

    The recent dramatic rise in power conversion efficiencies (PCE) of perovskite solar cells has triggered intense research worldwide. However, their practical development is hampered by poor stability and low PCE values with large areas devices. Here, we developed a gas-pumping method to avoid pinholes and eliminate local structural defects over large areas of perovskite film, even for 5 × 5 cm2 modules, the PCE reached 10.6% and no significant degradation was found after 140 days of outdoor testing. Our approach enables the realization of high performance large-area PSCs for practical application.

  14. Fabrication of stable, large-area thin-film CdTe photovoltaic modules. Final subcontract report, May 10, 1991--February 28, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, T.X. [Solar Cells, Inc., Toledo, OH (United States)

    1995-06-01

    During the period of this subcontract, May 1991 through February 1995, Solar Cells, Inc. has developed and demonstrated a low-cost process to fabricate stable large-area cadmium telluride based thin-film photovoltaic modules. This report summarizes the final phase of the project which is concentrated on process optimization and product life tests. One of the major post-deposition process steps, the CdCl{sub 2} heat treatment, has been experimentally replaced with alternative treatments with vapor chloride or chlorine gas. Material and device qualities associated with alternative treatments are comparable or superior to those with the conventional treatment. Extensive experiments have been conducted to optimize the back-electrode structure in order to ensure long term device stability. Numerous small-area cells and minimodules have been subjected to a variety of stress tests, including but not limited to continuous light soak under open or short circuit or with resistive load, for over 10,000 hours. Satisfactory stability has been demonstrated on 48 cm{sup 2} and 64 cm{sup 2} minimodules under accelerated tests and on 7200 cm{sup 2} large modules under normal operating conditions. The conversion efficiency has also been significantly improved during this period. The total area efficiency of 7200 cm{sup 2} module has reached 8.4%, corresponding to a 60.3W normalized output; the efficiency of 64 cm{sup 2} minimodules and 1.1 cm{sup 2} cells has reached 10.5% (aperture area) and 12.4% (total area), respectively.

  15. Large area bulk superconductors

    Science.gov (United States)

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  16. Experimental investigation on the large-area fabrication of micro-pyramid arrays by roll-to-roll hot embossing on PVC film

    Science.gov (United States)

    Deng, Yujun; Yi, Peiyun; Peng, Linfa; Lai, Xinmin; Lin, Zhongqin

    2014-04-01

    Large-area polymeric components with micro-pyramids have been widely applied in the fields of optics, optoelectronics, biology and chemistry, etc. Roll-to-roll (R2R) hot embossing is regarded as a promising approach to fulfil high throughput fabrication of patterned polymeric films. In this study, an R2R hot embossing system has been developed in-house and effective and continuous production of the polymeric component with micro-pyramids is demonstrated by R2R hot embossing. The influence of processing parameters has been firstly investigated by using the one-variable-at-a-time method. Afterwards, a series of experiments based on the central composite design approach have been conducted for the analysis of variance and the establishment of empirical models of the R2R hot embossing process. As a result, a 90 mm × 90 mm PVC sample with a feature height of 65 µm was successfully fabricated and the height consistency reached 94.5%. Additionally, a process window with a mold temperature of 150-160 °C, an applied force of 18-25 kgf and a feeding speed of 0.3-0.5 m min-1, was established to achieve 100% passable micro-pyramid arrays. The processing rules and the concrete ranges of parameter values can guide the process production of large-area micro-pyramids.

  17. High speed inscription of uniform, large-area laser-induced periodic surface structures in Cr films using a high repetition rate fs laser.

    Science.gov (United States)

    Ruiz de la Cruz, A; Lahoz, R; Siegel, J; de la Fuente, G F; Solis, J

    2014-04-15

    We report on the fabrication of laser-induced periodic surface structures in Cr films upon high repetition rate fs laser irradiation (up to 1 MHz, 500 fs, 1030 nm), employing beam scanning. Highly regular large-area (9  cm2) gratings with a relative diffraction efficiency of 42% can be produced within less than 6 min. The ripple period at moderate and high fluences is 0.9 μm, with a small period of 0.5 μm appearing at lower energies. The role of the irradiation parameters on the characteristics of the laser-induced periodic surface structures (LIPSS) is studied and discussed in the frame of the models presently used. We have identified the polarization vector orientation with respect to the scan direction as a key parameter for the fabrication of high-quality, large-area LIPSS, which, for perpendicular orientation, allows the coherent extension of the sub-wavelength structure over macroscopic distances. The processing strategy is robust in terms of broad parameter windows and applicable to other materials featuring LIPSS.

  18. Large area plasma source

    Science.gov (United States)

    Foster, John (Inventor); Patterson, Michael (Inventor)

    2008-01-01

    An all permanent magnet Electron Cyclotron Resonance, large diameter (e.g., 40 cm) plasma source suitable for ion/plasma processing or electric propulsion, is capable of producing uniform ion current densities at its exit plane at very low power (e.g., below 200 W), and is electrodeless to avoid sputtering or contamination issues. Microwave input power is efficiently coupled with an ionizing gas without using a dielectric microwave window and without developing a throat plasma by providing a ferromagnetic cylindrical chamber wall with a conical end narrowing to an axial entrance hole for microwaves supplied on-axis from an open-ended waveguide. Permanent magnet rings are attached inside the wall with alternating polarities against the wall. An entrance magnet ring surrounding the entrance hole has a ferromagnetic pole piece that extends into the chamber from the entrance hole to a continuing second face that extends radially across an inner pole of the entrance magnet ring.

  19. Room-temperature ferromagnetism in thin films of LaMnO3 deposited by a chemical method over large areas.

    Science.gov (United States)

    Vila-Fungueiriño, José Manuel; Rivas-Murias, Beatriz; Rodríguez-González, Benito; Txoperena, O; Ciudad, D; Hueso, Luis E; Lazzari, Massimo; Rivadulla, Francisco

    2015-03-11

    Hole-doping into the Mott insulator LaMnO3 results in a very rich magneto-electric phase diagram, including colossal magnetoresistance and different types of charge and orbital ordering. On the other hand, LaMnO3 presents an important catalytic activity for oxygen reduction, which is fundamental for increasing the efficiency of solid-oxide fuel cells and other energy-conversion devices. In this work, we report the chemical solution (water-based) synthesis of high-quality epitaxial thin films of LaMnO3, free of defects at square-centimeter scales, and compatible with standard microfabrication techniques. The films show a robust ferromagnetic moment and large magnetoresistance at room temperature. Through a comparison with films grown by pulsed laser deposition, we show that the quasi-equilibrium growth conditions characteristic of this chemical process can be exploited to tune new functionalities of the material.

  20. Improving the optical and crystalline properties on CdS thin films growth on small and large area by using CBD technique

    Energy Technology Data Exchange (ETDEWEB)

    Albor A, M. L.; Flores M, J. M.; Hernandez V, C.; Contreras P, G.; Mejia G, C.; Rueda M, G. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, Unidad Profesional Adolfo Lopez Mateos, Zacatenco, 07738 Ciudad de Mexico (Mexico); Gonzalez T, M. A. [IPN, Escuela Superior de Computo, Departamento de Formacion Basica, Unidad Profesional Adolfo Lopez Mateos, 07738 Ciudad de Mexico (Mexico)

    2016-11-01

    CdS polycrystalline thin films have been used as window layer in solar cells; the optical and crystalline quality of the CdS-partner plays and important role in the photovoltaic device performance. CdS thin films were deposited by using Chemical Bath Deposition. The SnO{sub 2}:F substrates used were chemically treated with HCl (0.1 M) and others were thermally annealed in different atmospheres (Ar and O{sub 2}). The physical properties of CdS thin films were influenced by the HCl treatment, position, size and the substrates movement inside the reaction beaker. The CdS samples were deposited in areas of 4 cm{sup 2}, 50 cm{sup 2} and 100 cm{sup 2}. Finally CdS thin films with thickness of 35-300 nm with good optical and crystalline quality on a uniform morphology were obtained. Transmittance values were obtained for all samples about 85-90 % with an average of gap energy of 2.5 eV. The structural characteristics of the samples were determined by the X-ray diffraction patterns, by means of a D-500 Siemens X-ray system. (Author)

  1. Large-Scale Graphene Film Deposition for Monolithic Device Fabrication

    Science.gov (United States)

    Al-shurman, Khaled

    Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors. The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an urgent need for a new platform material to replace Si. Graphene is considered a promising material with enormous potential applications in many electronic and optoelectronics devices due to its superior properties. There are several techniques to produce graphene films. Among these techniques, chemical vapor deposition (CVD) offers a very convenient method to fabricate films for large-scale graphene films. Though CVD method is suitable for large area growth of graphene, the need for transferring a graphene film to silicon-based substrates is required. Furthermore, the graphene films thus achieved are, in fact, not single crystalline. Also, graphene fabrication utilizing Cu and Ni at high growth temperature contaminates the substrate that holds Si CMOS circuitry and CVD chamber as well. So, lowering the deposition temperature is another technological milestone for the successful adoption of graphene in integrated circuits fabrication. In this research, direct large-scale graphene film fabrication on silicon based platform (i.e. SiO2 and Si3N4) at low temperature was achieved. With a focus on low-temperature graphene growth, hot-filament chemical vapor deposition (HF-CVD) was utilized to synthesize graphene film using 200 nm thick nickel film. Raman spectroscopy was utilized to examine graphene formation on the bottom side of the Ni film

  2. Fabrication of stable large-area thin-film CdTe photovoltaic modules. Annual subcontract report, 10 May 1992--9 May 1993

    Energy Technology Data Exchange (ETDEWEB)

    Nolan, J.F.; Meyers, P.V. [Solar Cells, Inc., Toledo, OH (United States)

    1993-08-01

    This report highlights the progress made by Solar Cells, Inc. (SCI), in its program to produce 60-cm {times} 120-cm solar modules based on CdTe films. During the past year, confirmed efficiency has increased to 10.4% (active area) on a 1 cm{sup 2} cell, 9.8% (aperture area) on a 64-cm{sup 2} 8-cell submodule, and 6.6% (total area) on a 7200-cm{sup 2} module. A module measured in-house had a power output of 53 W, for a total-area efficiency of 7.4%. Average efficiency of modules produced is steadily increasing and standard deviation is decreasing; in a limited run of 12 modules, results were 6.3% ({plus_minus} 0.2%). Field testing has begun; a nominal 1-kW array of 24 modules was set up adjacent to SCI`s facilities. Analysis indicates that present modules are limited in efficiency by shunt resistance and optical absorption losses in the glass superstrate. Loss analysis of present devices allows us to project a module efficiency of 11.8%. A third generation deposition method -- atmospheric pressure elemental vapor deposition (APEVD) has been brought on-line and has produced good quality CdTe. In addition, SCI is expanding its proactive safety, health, environmental, and disposal program dealing with issues surrounding cadmium.

  3. Large area superconducting YBa sub 2 Cu sub 3 O sub 7-x films grown by single target ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Gauzzi, A.; Lucia, M.L.; Kellett, B.J.; James, J.H.; Pavuna, D. (Inst. of Micro- and Optoelectronics, Swiss Federal Inst. of Tech., Lausanne (Switzerland))

    1991-10-20

    We have demonstrated, by using a simple single YBa{sub 2}Cu{sub 3}O{sub 7-x} target ion beam system that, with a sufficiently low power ion beam, preferential sputtering is avoided and high-quality YBa{sub 2}Cu{sub 3}O{sub 7-x} films are deposited over areas larger than {approx equal}30 cm{sup 2} in a reproducible way. As-deposited films on <100>SrTiO{sub 3} are 50-100 nm thick, c-oriented and show the following reproducible electrical properties (within the given variations): Tc{sub 0}=90{+-}0.5 K, transitions widths less than 1 K, j{sub c}(77K)=1.0-1.2x10{sup 6} A cm{sup -2}, {rho}(300K)=300{+-}50 {mu}{Omega} cm, {rho}(300 K)/{rho}(100 K)=2.9{+-}0.1. The extrapolated residual resistivity {rho}{sub res}(0 K) is between 0 and 5% of {rho}(300 K). (orig.).

  4. Large area and flexible electronics

    CERN Document Server

    Caironi, Mario

    2015-01-01

    From materials to applications, this ready reference covers the entire value chain from fundamentals via processing right up to devices, presenting different approaches to large-area electronics, thus enabling readers to compare materials, properties and performance.Divided into two parts, the first focuses on the materials used for the electronic functionality, covering organic and inorganic semiconductors, including vacuum and solution-processed metal-oxide semiconductors, nanomembranes and nanocrystals, as well as conductors and insulators. The second part reviews the devices and applicatio

  5. Chemical Vapour Deposition of Large Area Graphene

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget

    be eliminated. Further opportunities arise when exchanging the copper foil for copper thin film on a wafer e.g. better integration with current cleanroom processing of devices and better control over the copper crystallinity. Typical strategies for controlling the temperature during CVD fabrication of graphene...... of thermocouples leads to large variations in the grown graphene. This was solved by controlling the temperature through applying a set power to the heat source, resulting in a more stable temperature from process to process. Micro Raman spectroscopy is used to characterize the structural quality of the grown......Chemical Vapor Deposition (CVD) is a viable technique for fabrication of large areas of graphene. CVD fabrication is the most prominent and common way of fabricating graphene in industry. In this thesis I have attempted to optimize a growth recipe and catalyst layer for CVD fabrication of uniform...

  6. Development of large-area monolithically integrated silicon-film{trademark} photovoltaic modules. Final subcontract report, May 1, 1991--December 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Hall, R.B.; Rand, J.A.; Cotter, J.E. [AstroPower, Inc., Newark, DE (United States)

    1995-04-01

    The objective of this program is to develop Silicon Film{trademark} Product III into a low-cost, stable solar cell for large-scale terrestrial power applications. The Product III structure is a thin (<100 {mu}m) polycrystalline layer of silicon on a durable, insulating, ceramic substrate. The insulating substrate allows the silicon layer to be isolated and metallized to form a monolithically interconnected array of solar cells. High efficiency is achieved by the use of light trapping and passivated surfaces. This project focused on the development of five key technologies associated with the monolithic sub-module device structure: (1) development of the film deposition and growth processes; (2) development of the low-cost ceramic substrate; (3) development of a metallurgical barrier technology; (4) development of sub-element solar cell processing techniques; and (5) development of sub-module (isolation and interconnection) processes. This report covers the development approaches and results relating to these technologies. Significant progress has been made in the development of all of the related technologies. This is evidenced by the fabrication of a working 12.0 cm{sup 2} prototype sub-module consisting of 7 elements and testing with an open circuit voltage of 3.9 volts, a short circuit current of 35.2 mA and a fill factor of 63% and an overall efficiency of 7.3%. Another significant result achieved is a 13.4% (NREL verified), 1.0 cm{sup 2} solar cell fabricated from material deposited and grown on a graphite cloth substrate. The significant technological hurdle of the program was and remains the low quality of the photovoltaic layer which is caused by contamination of the photovoltaic layer from the low-cost ceramic substrate by trace impurities found in the substrate precursor materials. The ceramic substrate and metallurgical barrier are being developed specifically to solve this problem.

  7. Development of Tandem Amorphous/Microcrystalline Silicon Thin-Film Large-Area See-Through Color Solar Panels with Reflective Layer and 4-Step Laser Scribing for Building-Integrated Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Chin-Yi Tsai

    2014-01-01

    Full Text Available In this work, tandem amorphous/microcrystalline silicon thin-film large-area see-through color solar modules were successfully designed and developed for building-integrated photovoltaic applications. Novel and key technologies of reflective layers and 4-step laser scribing were researched, developed, and introduced into the production line to produce solar panels with various colors, such as purple, dark blue, light blue, silver, golden, orange, red wine, and coffee. The highest module power is 105 W and the highest visible light transmittance is near 20%.

  8. Fabrication of large area flexible nanoplasmonic templates with flow coating

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qian; Devetter, Brent M.; Roosendaal, Timothy; LaBerge, Max; Bernacki, Bruce E.; Alvine, Kyle J.

    2017-07-01

    We describe the development of a custom-built two-axis flow coater for the deposition of polymeric nanosphere monolayers used in the fabrication of large area nanoplasmonic films. The technique described here has the capability of depositing large areas (up to 7” x 10”) of self-assembled monolayers of polymeric nanospheres onto polyethylene terephthalate (PET) films. Here, three sets of film consisting of different diameter (ranging from 100 to 300 nm) polymeric nanospheres were used to demonstrate the capabilities of this instrument. To improve the surface wettability of the PET substrates during wet-deposition we enhanced the wettability by using a forced air blown-arc plasma treatment system. Both the local microstructure, as confirmed by scanning electron microscopy, describing monolayer and multilayer coverage, and the overall macroscopic uniformity of the resultant nanostructured film were optimized by controlling the relative stage to blade speed and nanosphere concentration. As this is a scalable technique, large area films such as the ones described here, have a variety of crucial emerging applications in areas such as energy, catalysis, and chemical sensing.

  9. Large area CMOS image sensors

    Science.gov (United States)

    Turchetta, R.; Guerrini, N.; Sedgwick, I.

    2011-01-01

    CMOS image sensors, also known as CMOS Active Pixel Sensors (APS) or Monolithic Active Pixel Sensors (MAPS), are today the dominant imaging devices. They are omnipresent in our daily life, as image sensors in cellular phones, web cams, digital cameras, ... In these applications, the pixels can be very small, in the micron range, and the sensors themselves tend to be limited in size. However, many scientific applications, like particle or X-ray detection, require large format, often with large pixels, as well as other specific performance, like low noise, radiation hardness or very fast readout. The sensors are also required to be sensitive to a broad spectrum of radiation: photons from the silicon cut-off in the IR down to UV and X- and gamma-rays through the visible spectrum as well as charged particles. This requirement calls for modifications to the substrate to be introduced to provide optimized sensitivity. This paper will review existing CMOS image sensors, whose size can be as large as a single CMOS wafer, and analyse the technical requirements and specific challenges of large format CMOS image sensors.

  10. Development of process technology for large-area thin-film solar modules based on compound semiconductors. Final report; Entwicklung der technologischen Grundlagen fuer grosse Photovoltaikmodule auf Basis von Duennschicht-Verbindungshalbleitern. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Maurus, H.; Lechner, P.; Geyer, R.; Ruebel, H.; Schade, H.; Psyk, W.; Frammelsberger, W.; Berthold, W.; Eichner, C.; Heckel, E.; Huber, R.; Labudde-Eibl, H.; Raith, S.; Schenk, B.; Ullrich, H.

    1998-06-01

    A cooperative effort of the Center for Solar Energy and Hydrogen Research (ZSW) and Phototronics Solartechnik GmbH (PST) aimed at the transfer of highly efficient solar cells developed on a laboratory scale, to large-area thin-film solar modules suitable for production. This work was based on research and development at the Institute for Physical Electronics (IPE) of Stuttgart University and ZSW on one hand, and on the know-how of PST in regard to large-area module fabrication on the other hand. The various thin-film layers of the cells and modules comprize molybdenum as rear contact, copper-indium(gallium)-diselenide (CIGS) as absorber material, the combination of cadmium sulphide (CdS) and ZnO as window layer. To produce these layers on large areas (30x30 cm{sup 2}), equipment was constructed and procedures were developed. Monolithic series connection of cells, used in other thin-film technologies, was studied and optimized by suitable patterning procedures, such as laser-scribing, mechanical scribing or lift-off techniques. Central to the PST efforts was the large-area deposition of Mo followed by patterning for the monolithic series connection, and furthermore important contributions in regard to the ZnO window layer as well as aspects of the module technology. The latter include film removal along the module edges, contacting and cable attachment, lamination, module measurements and temperature/humidity tests. The main goal, namely the basic development of equipment and procedures to fabricate large-area (30x30 cm{sup 2}) modules with an efficiency of 10-12%, was reached (best module with 11.7% efficiency referenced to the aperature area). (orig.) [Deutsch] Um die im Labormassstab entwickelten hocheffizienten Solarzellen in industriell relevante grossflaechige Duennschichtmodule umzusetzen, arbeiteten das Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung (ZSW) Baden-Wuerttemberg und die Phototronics Solartechnik GmbH (PST) zusammen. Ausgangsbasis waren

  11. Plasma and Ion Sources in Large Area Coatings: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  12. Mapping the electrical properties of large-area graphene

    DEFF Research Database (Denmark)

    Bøggild, Peter; Mackenzie, David; Whelan, Patrick Rebsdorf

    2017-01-01

    The significant progress in terms of fabricating large-area graphene films for transparent electrodes, barriers, electronics, telecommunication and other applications has not yet been accompanied by efficient methods for characterizing the electrical properties of large-area graphene. While...... in the early prototyping as well as research and development phases, electrical test devices created by conventional lithography have provided adequate insights, this approach is becoming increasingly problematic due to complications such as irreversible damage to the original graphene film, contamination......, and a high measurement effort per device. In this topical review, we provide a comprehensive overview of the issues that need to be addressed by any large-area characterisation method for electrical key performance indicators, with emphasis on electrical uniformity and on how this can be used to provide...

  13. Large area plasma deposition of microcrystalline silicon for micromorph thin-film solar modules; Grossflaechige Plasmaabscheidung von mikrokristallinem Silizium fuer mikromorphe Duennschichtsolarmodule

    Energy Technology Data Exchange (ETDEWEB)

    Kilper, Thilo

    2009-07-01

    This thesis addresses aspects of {mu}c-Si:H absorber layer fabrication that possess a high technological relevance for the industrial serial production of micromorph thin-film solar modules. The performed investigations focused on a) the {mu}c-Si:H absorber layer deposition rate, b) low total gas flow processes that exhibit a high silane utilization and a distinctly reduced hydrogen consumption, and c) the influence of oxygen and nitrogen impurities on the performance of {mu}c-Si:H solar cells. For the fabrication of {mu}c-Si:H absorber layers in a 30 x 30 cm{sup 2} PECVD reactor equipped with rf planar electrodes, it was found that an increase of the plasma excitation frequency from 13.56 to 40.68 MHz enables significant higher deposition rates without losses in cell performance and film homogeneity. 40.68 MHz {mu}c-Si:H solar cells prepared at RD = 1 nm/s yielded conversion efficiencies up to 9.2 % and had a similar good performance as 13.56 MHz {mu}c-Si:H solar cells deposited at RD = 0.5 nm/s. At deposition rates of 2.5 nm/s 40,68 MHz {mu}c-Si:H solar cells exhibited cell efficiencies of nearly 8 %. Moreover, it was demonstrated that 40.68 MHz {mu}c-Si:H absorber layers on 30 x 30 cm{sup 2} substrates have a similar good homogeneity as 13.56 MHz {mu}c-Si:H absorber layers concerning the film thickness and the material properties. By implementing a process control it was possible to suppress the strong initial process drift of a 13.56 MHz 0.5 nm/s {mu}c-Si:H low total gas flow process in the 30 x 30 cm{sup 2} PECVD reactor. Due to the successful stabilization of the {mu}c-Si:H growth conditions during the complete absorber layer deposition procedure, an efficiency enhancement of +1 % absolute was gained and the best {mu}c-Si:H solar cells prepared with the controlled low total gas flow process yielded efficiencies of 8.8 %. However, compared to standard gas flow processes it was found that this controlled low total gas flow process exhibits a worse homogeneity

  14. Research on fabrication technology for thin film solar cells for practical use. Research on low-cost fabrication technology for large-area modules (CdS/CdTe solar cell modules); Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu. Daimenseki module no tei cost seizo gijutsu (CdTe taiyo denchi module seizo no gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Tatsuta, M. [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

    1994-12-01

    This paper reports the study results on the fabrication technology of CdS/CdTe solar cell modules in fiscal 1994. (1) On the fabrication technology for high-efficiency large-area solar cells, high-quality CdTe active layer was studied. S content taken in the active layer at sintering of CdTe decreased with an increase in formed CdTe, resulting in improvement of Voc of cells. (2) On the window layer with wide band gap, the solar cell superior in collection efficiency and photoelectric characteristics could be obtained using the newly developed mixed crystal film of Cd(1-x)Zn(x)S. (3) On the forming technology of large-area coating/sintering films, improvement of CdS film quality was studied by pressurized processing of printed CdS films. As a result, improvement of film density and light transmissivity was confirmed. (4) On the leveling process technology of CdTe films, smooth surface films were obtained by experiment using an equipment simultaneously exciting samples in all directions as one of uniform coating methods of films. 7 figs.

  15. Development of practical application technology for photovoltaic power generation systems in fiscal 1997. Development of technologies to manufacture thin film solar cells, development of technologies to manufacture low-cost large-area modules (dissolution and deposition process); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu. Usumaku taiyo denchi no seizo gijutsu kaihatsu, tei cost daimenseki module seizo gijutsu kaihatsu (yokai sekishutsuho)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Research and development was performed by noticing on the plasma spraying method as a process that can manufacture thin poly-crystalline silicon films at a high speed. Fiscal 1997 has established a technology that can form a silicon film directly without using seed crystals in an area of 2-cm square on a carbon supported substrate by using a small film manufacturing equipment using the dissolution and deposition process. The size of the crystal is as very large as several hundred {mu}m, by which a possibility of making high-performance solar cells was verified. Discussions were given to apply this technology to large-area substrates, whereas a device was developed, which is capable of forming a film in an area corresponding to 10-cm square. According to a film forming experiment using this device, the film has begun being formed on part of a 10-cm square substrate, verifying the effectiveness of this method. While the film thickness is about 100 {mu}m, it was confirmed that the crystal size will not change even if the thickness is made mechanically as thin as about 50 {mu}m. Further discussions were given on enhancement of wettability by means of coating, and light enclosing structure. (NEDO)

  16. The European Large Area ISO Survey

    DEFF Research Database (Denmark)

    Oliver, S.; Rowan-Robinson, M.; Alexander, D.M.

    2000-01-01

    We describe the European Large Area ISO Survey (ELAIS). ELAIS was the largest single Open Time project conducted by ISO, mapping an area of 12 deg(2) at 15 mu m with ISOCAM and at 90 mu m with ISOPHOT. Secondary surveys in other ISO bands were undertaken by the ELAIS team within the fields...

  17. Development of large-area glass GEM

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuya, Yuki, E-mail: yukimitsuya@sophie.q.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan); Fujiwara, Takeshi [Research Institute for Measurement and Analytical Instrumentation, National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Fushie, Takashi [HOYA Corporation, 3280 Nakamaru, Nagasaka-cho, Hokuto-city, Yamanashi 408-8550 (Japan); Maekawa, Tatsuyuki [Toshiba Corporation, 8 Shinsugita-cho, Isogo-ku, Yokohama-city, Kanagawa 235-8523 (Japan); Takahashi, Hiroyuki [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

    2015-09-21

    We have developed a new gaseous radiation detector, referred to as the Glass GEM (G-GEM). The G-GEM is composed of a photosensitive etching glass (PEG3) substrate from HOYA Corporation, Japan. Since a large-area detector is required for imaging device applications, we newly developed a large-area G-GEM prototype with a sensitive area of 280×280 mm{sup 2}. In this study, we investigated its basic characteristics and confirmed that it worked properly and had sufficient uniformity across the entire sensitive area. It had high gas gain of up to approximately 7700, along with good energy resolution of 26.2% (FWHM) for a 5.9-keV X-ray with a gas mixture of Ar (90%) and CH4 (10%). The gain variation across the sensitive area was almost within the range of ±10%.

  18. Large-area lanthanum hexaboride electron emitter

    Science.gov (United States)

    Goebel, D. M.; Hirooka, Y.; Sketchley, T. A.

    1985-09-01

    The characteristics of lanthanum-boron thermionic electron emitters are discussed, and a large-area, continuously operating cathode assembly and heater are described. Impurity production and structural problems involving the support of the LaB6 have been eliminated in the presented configuration. The performance of the cathode in a plasma discharge, where surface modification occurs by ion sputtering, is presented. Problem areas which affect lifetime and emission current capability are discussed.

  19. Large Area Roller Embossing of Multilayered Ceramic Green Composites

    CERN Document Server

    Shan, X; Shi, C W P; Tay, C K; Lu, C W

    2008-01-01

    In this paper, we will report our achievements in developing large area patterning of multilayered ceramic green composites using roller embossing. The aim of our research is to pattern large area ceramic green composites using a modified roller laminating apparatus, which is compatible with screen printing machines, for integration of embossing and screen printing. The instrumentation of our roller embossing apparatus, as shown in Figure1, consists of roller 1 and rollers 2. Roller 1 is heated up to the desired embossing temperature ; roller 2 is, however, kept at room temperature. The mould is a nickel template manufactured by plating nickel-based micro patterns (height : 50 $\\mu$m) on a nickel film (thickness : 70 $\\mu$m) ; the substrate for the roller embossing is a multilayered Heraeus Heralock HL 2000 ceramic green composite. Comparing with the conventional simultaneous embossing, the advantages of roller embossing include : (1) low embossing force ; (2) easiness of demoulding ; (3) localized area in co...

  20. Quantitative Mapping of Large Area Graphene Conductance

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due; Petersen, Dirch Hjorth; Bøggild, Peter

    2012-01-01

    We present quantitative mapping of large area graphene conductance by terahertz time-domain spectroscopy and micro four point probe. We observe a clear correlation between the techniques and identify the observed systematic differences to be directly related to imperfections of the graphene sheet...

  1. Stability of large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

    The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

  2. A new large area monolithic silicon telescope

    CERN Document Server

    Tudisco, S; Cabibbo, M; Cardella, G; De Geronimo, G; Di Pietro, A; Fallica, G; Figuera, P; Musumarra, A; Papa, M; Pappalardo, G S; Rizzo, F; Valvo, G

    1999-01-01

    A new prototype of large area (20x20 mm sup 2) monolithic silicon telescope with an ultrathin DELTA E stage (1 mu m) has been built and tested. A particular mask for the ground electrode has been developed to improve the charge collection reducing the induction between the E and DELTA E stages. A special designed preamplifier has been used for the readout of the signal from the DELTA E stage to overcome the problem of the large input capacitance (40 nF). A rather low energy threshold charge discrimination has been obtained. Small side effects due to the electric field deformation near the ground electrode were observed and quantified.

  3. High-Throughput Dry Processes for Large-Area Devices

    Energy Technology Data Exchange (ETDEWEB)

    BUSS,RICHARD J.; HEBNER,GREGORY A.; RUBY,DOUGLAS S.; YANG,PIN

    1999-11-01

    In October 1996, an interdisciplinary team began a three-year LDRD project to study the plasma processes of reactive ion etching and plasma-enhanced chemical vapor deposition on large-area silicon devices. The goal was to develop numerical models that could be used in a variety of applications for surface cleaning, selective etching, and thin-film deposition. Silicon solar cells were chosen as the experimental vehicle for this project because an innovative device design was identified that would benefit from immediate performance improvement using a combination of plasma etching and deposition processes. This report presents a summary of the technical accomplishments and conclusions of the team.

  4. Large-Area Vacuum Ultraviolet Sensors

    Science.gov (United States)

    Aslam, Shahid; Franz, David

    2012-01-01

    Pt/(n-doped GaN) Schottky-barrier diodes having active areas as large as 1 cm square have been designed and fabricated as prototypes of photodetectors for the vacuum ultraviolet portion (wavelengths approximately equal 200 nm) of the solar spectrum. In addition to having adequate sensitivity to photons in this wavelength range, these photodetectors are required to be insensitive to visible and infrared components of sunlight and to have relatively low levels of dark current.

  5. Timing Characteristics of Large Area Picosecond Photodetectors

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  6. Viable route towards large-area 2D MoS2 using magnetron sputtering

    Science.gov (United States)

    Samassekou, Hassana; Alkabsh, Asma; Wasala, Milinda; Eaton, Miller; Walber, Aaron; Walker, Andrew; Pitkänen, Olli; Kordas, Krisztian; Talapatra, Saikat; Jayasekera, Thushari; Mazumdar, Dipanjan

    2017-06-01

    Structural, interfacial, optical, and transport properties of large-area MoS2 ultra-thin films on BN-buffered silicon substrates fabricated using magnetron sputtering are investigated. A relatively simple growth strategy is demonstrated here that simultaneously promotes superior interfacial and bulk MoS2 properties. Few layers of MoS2 are established using x-ray reflectivity, diffraction, ellipsometry, and Raman spectroscopy measurements. Layer-specific modeling of optical constants show very good agreement with first-principles calculations. Conductivity measurements reveal that few-layer MoS2 films are more conducting than many-layer films. Photo-conductivity measurements reveal that the sputter deposited MoS2 films compare favorably with other large-area methods. Our work illustrates that sputtering is a viable route for large-area device applications using transition metal dichalcogenides.

  7. Supernova Remnants with Fermi Large Area Telescope

    Directory of Open Access Journals (Sweden)

    Caragiulo M.

    2017-01-01

    Full Text Available The Large Area Telescope (LAT, on-board the Fermi satellite, proved to be, after 8 years of data taking, an excellent instrument to detect and observe Supernova Remnants (SNRs in a range of energies running from few hundred MeV up to few hundred GeV. It provides essential information on physical processes that occur at the source, involving both accelerated leptons and hadrons, in order to understand the mechanisms responsible for the primary Cosmic Ray (CR acceleration. We show the latest results in the observation of Galactic SNRs by Fermi-LAT.

  8. Modeling of large area hot embossing

    CERN Document Server

    Worgull, M; Marcotte, J -P; Hétu, J -F; Heckele, M

    2008-01-01

    Today, hot embossing and injection molding belong to the established plastic molding processes in microengineering. Based on experimental findings, a variety of microstructures have been replicated so far using the processes. However, with increasing requirements regarding the embossing surface and the simultaneous decrease of the structure size down into the nanorange, increasing know-how is needed to adapt hot embossing to industrial standards. To reach this objective, a German-Canadian cooperation project has been launched to study hot embossing theoretically by a process simulation and experimentally. The present publication shall report about the first results of the simulation - the modeling and simulation of large area replication based on an eight inch microstructured mold.

  9. Large-area mapping of biodiversity

    Science.gov (United States)

    Scott, J.M.; Jennings, M.D.

    1998-01-01

    The age of discovery, description, and classification of biodiversity is entering a new phase. In responding to the conservation imperative, we can now supplement the essential work of systematics with spatially explicit information on species and assemblages of species. This is possible because of recent conceptual, technical, and organizational progress in generating synoptic views of the earth's surface and a great deal of its biological content, at multiple scales of thematic as well as geographic resolution. The development of extensive spatial data on species distributions and vegetation types provides us with a framework for: (a) assessing what we know and where we know it at meso-scales, and (b) stratifying the biological universe so that higher-resolution surveys can be more efficiently implemented, coveting, for example, geographic adequacy of specimen collections, population abundance, reproductive success, and genetic dynamics. The land areas involved are very large, and the questions, such as resolution, scale, classification, and accuracy, are complex. In this paper, we provide examples from the United States Gap Analysis Program on the advantages and limitations of mapping the occurrence of terrestrial vertebrate species and dominant land-cover types over large areas as joint ventures and in multi-organizational partnerships, and how these cooperative efforts can be designed to implement results from data development and analyses as on-the-ground actions. Clearly, new frameworks for thinking about biogeographic information as well as organizational cooperation are needed if we are to have any hope of documenting the full range of species occurrences and ecological processes in ways meaningful to their management. The Gap Analysis experience provides one model for achieving these new frameworks.

  10. Fermi Large Area Telescope Second Source Catalog

    Science.gov (United States)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Cañadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; DeCesar, M. E.; DeKlotz, M.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Van Etten, A.; Van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

    2012-04-01

    We present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes. We dedicate this paper to the memory of our colleague Patrick Nolan, who died on 2011 November 6. His career spanned much of the history of high-energy astronomy from space and his work on the Large Area Telescope (LAT) began nearly 20 years ago when it was just a concept. Pat was a central member in the operation of the LAT collaboration and he is greatly missed.

  11. Development of large Area Covering Height Model

    Science.gov (United States)

    Jacobsen, K.

    2014-04-01

    Height information is a basic part of topographic mapping. Only in special areas frequent update of height models is required, usually the update cycle is quite lower as for horizontal map information. Some height models are available free of charge in the internet; for commercial height models a fee has to be paid. Mostly digital surface models (DSM) with the height of the visible surface are given and not the bare ground height, as required for standard mapping. Nevertheless by filtering of DSM, digital terrain models (DTM) with the height of the bare ground can be generated with the exception of dense forest areas where no height of the bare ground is available. These height models may be better as the DTM of some survey administrations. In addition several DTM from national survey administrations are classified, so as alternative the commercial or free of charge available information from internet can be used. The widely used SRTM DSM is available also as ACE-2 GDEM corrected by altimeter data for systematic height errors caused by vegetation and orientation errors. But the ACE-2 GDEM did not respect neighbourhood information. With the worldwide covering TanDEM-X height model, distributed starting 2014 by Airbus Defence and Space (former ASTRIUM) as WorldDEM, higher level of details and accuracy is reached as with other large area covering height models. At first the raw-version of WorldDEM will be available, followed by an edited version and finally as WorldDEM-DTM a height model of the bare ground. With 12 m spacing and a relative standard deviation of 1.2 m within an area of 1° x 1° an accuracy and resolution level is reached, satisfying also for larger map scales. For limited areas with the HDEM also a height model with 6 m spacing and a relative vertical accuracy of 0.5 m can be generated on demand. By bathymetric LiDAR and stereo images also the height of the sea floor can be determined if the water has satisfying transparency. Another method of getting

  12. Meteor Film Recording with Digital Film Cameras with large CMOS Sensors

    Science.gov (United States)

    Slansky, P. C.

    2016-12-01

    In this article the author combines his professional know-how about cameras for film and television production with his amateur astronomy activities. Professional digital film cameras with high sensitivity are still quite rare in astronomy. One reason for this may be their costs of up to 20 000 and more (camera body only). In the interim, however,consumer photo cameras with film mode and very high sensitivity have come to the market for about 2 000 EUR. In addition, ultra-high sensitive professional film cameras, that are very interesting for meteor observation, have been introduced to the market. The particular benefits of digital film cameras with large CMOS sensors, including photo cameras with film recording function, for meteor recording are presented by three examples: a 2014 Camelopardalid, shot with a Canon EOS C 300, an exploding 2014 Aurigid, shot with a Sony alpha7S, and the 2016 Perseids, shot with a Canon ME20F-SH. All three cameras use large CMOS sensors; "large" meaning Super-35 mm, the classic 35 mm film format (24x13.5 mm, similar to APS-C size), or full format (36x24 mm), the classic 135 photo camera format. Comparisons are made to the widely used cameras with small CCD sensors, such as Mintron or Watec; "small" meaning 12" (6.4x4.8 mm) or less. Additionally, special photographic image processing of meteor film recordings is discussed.

  13. FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

    Energy Technology Data Exchange (ETDEWEB)

    Nolan, P. L.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Abdo, A. A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Ackermann, M. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Antolini, E.; Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Atwood, W. B.; Belfiore, A. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Axelsson, M. [Department of Astronomy, Stockholm University, SE-106 91 Stockholm (Sweden); Baldini, L.; Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d' Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bignami, G. F., E-mail: digel@stanford.edu, E-mail: Gino.Tosti@pg.infn.it, E-mail: jean.ballet@cea.fr, E-mail: tburnett@u.washington.edu [Istituto Universitario di Studi Superiori (IUSS), I-27100 Pavia (Italy); and others

    2012-04-01

    We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.

  14. Fermi Large Area Telescope Second Source Catalog

    CERN Document Server

    ,

    2011-01-01

    We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24-month period. The Second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in 5 energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we att...

  15. Fermi Large Area Telescope Second Source Catalog

    Science.gov (United States)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M; Allafort, A.; Antolini, E; Bonnell, J.; Cannon, A.; Celik O.; Corbet, R.; Davis, D. S.; DeCesar, M. E.; Ferrara, E. C.; Gehrels, N.; Harding, A. K.; Hays, E.; Johnson, T. E.; McConville, W.; McEnery, J. E; Perkins, J. S.; Racusin, J. L; Scargle, J. D.; Stephens, T. E.; Thompson, D. J.; Troja, E.

    2012-01-01

    We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24-month period. The Second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in 5 energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 11eV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely gamma-ray-producing source classes.

  16. Research on fabrication technology for thin film solar cells for practical use. Research on low-cost fabrication technology for large-area modules (Over-layered TCO on tempered glass for solar cell); Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu. Daimenseki module no tei cost seizo gijutsu (kyoka class fukugo tomei doden kiban seizo no gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Tatsuta, M. [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

    1994-12-01

    This paper reports the study results on the fabrication technology of over-layered TCO on tempered glass in fiscal 1994. (1) On the fabrication technology of heat-resistant over-layered TCO, thermal deformation of TCO substrates was studied by both experiment and numerical computation. The thermal deformation increased with carrier concentration. As the observation result on change in lattice strain of heated TCO films by high-temperature X-ray diffraction, lattice strain was largely affected by thermal expansion. (2) On development of the low-temperature heat treatment method of TCO films, a technological prospect was obtained for fabrication of low-resistance TCO films by heat treatment without strength deterioration of tempered TCO substrates. (3) On development of cost reduction technology, the large-area CVD equipment was devised on the basis of the inline tempering method which tempers substrate glass by air cooling after formation of SnO2 film as fabrication method of tempered TCO. The TCO substrate tempered by air cooling could endure the drop test of 227g and 1.5m. 5 figs., 1 tab.

  17. ISABELLE. Volume 3. Experimental areas, large detectors

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    This section presents the papers which resulted from work in the Experimental Areas portion of the Workshop. The immediate task of the group was to address three topics. The topics were dictated by the present state of ISABELLE experimental areas construction, the possibility of a phased ISABELLE and trends in physics and detectors.

  18. Mechanics of large folds in thin interfacial films

    Science.gov (United States)

    Démery, Vincent; Davidovitch, Benny; Santangelo, Christian D.

    2014-10-01

    A thin film confined to a liquid interface responds to uniaxial compression by wrinkling, and then by folding, that has been solved exactly before self-contact. Here, we address the mechanics of large folds, i.e., folds that absorb a length much larger than the wrinkle wavelength. With scaling arguments and numerical simulations, we show that the antisymmetric fold is energetically favorable and can absorb any excess length at zero pressure. Then, motivated by puzzles arising in the comparison of this simple model to experiments on lipid monolayers or capillary rafts, we discuss how to incorporate film weight, self-adhesion, or energy dissipation.

  19. Large Mode Area Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Nielsen, Martin Dybendal

    2004-01-01

    The photonic crystal fiber (PCF) is a novel single-material optical waveguide realized by an arrangement of air-holes running along the full length of the fiber. Since the proposal of the PCF in 1996, the technology has developed into being a well-established area of research and commercialisation......-mode area fiber optimised for visible light applications. The second is a fiber optimised for the telecommunication band realizing a nonlinear effective area 5 times larger than state of the art conventional fibers. Two examples of alternative designs are demonstrated addressing the core and the cladding...

  20. Tuning the thickness of electrochemically grafted layers in large area molecular junctions

    Energy Technology Data Exchange (ETDEWEB)

    Fluteau, T.; Bessis, C.; Barraud, C., E-mail: clement.barraud@univ-paris-diderot.fr; Della Rocca, M. L.; Lafarge, P. [Université Paris Diderot, Sorbonne Paris Cité, MPQ, UMR 7162, CNRS, 75205 Paris Cedex 13 (France); Martin, P.; Lacroix, J.-C. [Université Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, 15 rue J.-A. de Baïf, 75205 Paris Cedex 13 (France)

    2014-09-21

    We have investigated the thickness, the surface roughness, and the transport properties of oligo(1-(2-bisthienyl)benzene) (BTB) thin films grafted on evaporated Au electrodes, thanks to a diazonium-based electro-reduction process. The thickness of the organic film is tuned by varying the number of electrochemical cycles during the growth process. Atomic force microscopy measurements reveal the evolution of the thickness in the range of 2–27 nm. Its variation displays a linear dependence with the number of cycles followed by a saturation attributed to the insulating behavior of the organic films. Both ultrathin (2 nm) and thin (12 and 27 nm) large area BTB-based junctions have then been fabricated using standard CMOS processes and finally electrically characterized. The electronic responses are fully consistent with a tunneling barrier in case of ultrathin BTB film whereas a pronounced rectifying behavior is reported for thicker molecular films.

  1. Plastic film materials for dosimetry of very large absorbed doses

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne; Abdel-Rahim, F.

    1985-01-01

    of the polyhalostyrenes have essentially rate-independent and moderately temperature-dependent responses to such large doses of ionizing radiation. While radiation-induced optical absorption in the ultraviolet for polystyrene is unstable following irradiation, thus leading to an intrinsic low-intensity rate dependence......Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up...... to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response at such high doses are polyethylene terephthalate, high-density polyethylene, dyed polyvinylchloride...

  2. Effect of film area on critical electric potential for O/W emulsion films breakup

    Energy Technology Data Exchange (ETDEWEB)

    Mostowfi, F. [Schlumberger, Edmonton, AB (Canada). DBR Technology Center; Panchev, N. [Champion Technologies Inc., Houston, TX (United States); Masliyah, J.; Czarnecki, J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Bhattacharjee, S. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering

    2008-07-01

    This paper reported on a study in which the critical potentials for breakup of lecithin films were measured at 2 different length scales using 2 different experimental setups. The objective of the study was to explain the electric breakup mechanisms of water-in-oil (W/O) emulsion film based on the theory that larger film areas are less stable and vice versa. In both setups, an electric polarization was applied across an oil film formed between 2 separate water phases. Thin liquid films were formed in toluene using lecithin as surfactant. Lecithin molecules form bilayer films with a thickness of 4-6 nm. Critical potential of breakup were measured over a wide range of lecithin concentrations from 0.05 up to 10 wt per cent. The value of critical potentials in both apparatus showed similar trends. The critical potential for the film breakup was found to be low at low surfactant concentrations because of less stable films at low surface coverage. The increase in film stability at intermediate surfactant concentrations could be attributed to higher surface coverage with the surfactant. At high surfactant concentrations greater than 1 wt per cent, the critical potential asymptotes to about 300 mV. The saturation of critical potential could be explained by saturation of the interfaces with lecithin molecules.

  3. Towards large area THz electromagnetic metamaterials

    Science.gov (United States)

    Moser, H. O.; Bahou, M.; Chen, A.; Heussler, S. P.; Jian, L. K.; Kalaiselvi, S. M. P.; Liu, G.; Maniam, S. M.; bin Mahmood, Shahrain; Gu, P. D.; Wen, L.; Kong, J. A.; Chen, H. S.; Cheng, X. X.; Wu, B. I.; Casse, B. D. F.; Rockstuhl, C.; Lederer, F.

    2008-08-01

    Up to date, electromagnetic metamaterials (EM3) have been mostly fabricated by primary pattern generation via electron beam or laser writer. Such an approach is time-consuming and may have limitations of the area filled with structures. Especially, electron beam written structures are typically confined to areas of a few 100×100 μm2. However, for meaningful technological applications, larger quantities of good quality materials are needed. Lithography, in particular X-ray deep lithography, is well suited to accomplish this task. Singapore Synchrotron Light Source (SSLS) has been applying its LIGA process that includes primary pattern generation via electron beam or laser writer, X-ray deep lithography and electroplating to the micro/nano-manufacturing of high-aspect ratio structures to produce a variety of EM3 structures. Starting with Pendry's split ring resonators, we have pursued structure designs suitable for planar lithography since 2002 covering a range of resonance frequencies from 1 to 216 THz. More recently, string-like structures have also been included. Latest progress made in the manufacturing and characterization of quasi 3D metamaterials having either split ring or string structures over areas of about ~1 cm2 extension will be described.

  4. Single-grain Silicon Technology for Large Area X-ray Imaging

    NARCIS (Netherlands)

    Arslan, A.

    2015-01-01

    Digital flat panel X-ray imagers are currently using a-Si and poly-Si thin-film-transistors (TFTs). a-Si TFT permits the use of large area substrates, however, due to the amorphous nature, the carrier mobility is very low (<1 cm2/Vs). Poly-Si TFT improves the mobility (~150 cm2/Vs) but due to random

  5. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications

    Science.gov (United States)

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-01-01

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K−1m−1, down to the ultra-low κ = 0.55 ± 0.10 W K−1m−1 value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials. PMID:27650202

  6. Single-grain Silicon Technology for Large Area X-ray Imaging

    NARCIS (Netherlands)

    Arslan, A.

    2015-01-01

    Digital flat panel X-ray imagers are currently using a-Si and poly-Si thin-film-transistors (TFTs). a-Si TFT permits the use of large area substrates, however, due to the amorphous nature, the carrier mobility is very low (<1 cm2/Vs). Poly-Si TFT improves the mobility (~150 cm2/Vs) but due to random

  7. Ultra-low thermal conductivities in large-area Si-Ge nanomeshes for thermoelectric applications.

    Science.gov (United States)

    Perez-Taborda, Jaime Andres; Muñoz Rojo, Miguel; Maiz, Jon; Neophytou, Neophytos; Martin-Gonzalez, Marisol

    2016-09-21

    In this work, we measure the thermal and thermoelectric properties of large-area Si0.8Ge0.2 nano-meshed films fabricated by DC sputtering of Si0.8Ge0.2 on highly ordered porous alumina matrices. The Si0.8Ge0.2 film replicated the porous alumina structure resulting in nano-meshed films. Very good control of the nanomesh geometrical features (pore diameter, pitch, neck) was achieved through the alumina template, with pore diameters ranging from 294 ± 5nm down to 31 ± 4 nm. The method we developed is able to provide large areas of nano-meshes in a simple and reproducible way, being easily scalable for industrial applications. Most importantly, the thermal conductivity of the films was reduced as the diameter of the porous became smaller to values that varied from κ = 1.54 ± 0.27 W K(-1)m(-1), down to the ultra-low κ = 0.55 ± 0.10 W K(-1)m(-1) value. The latter is well below the amorphous limit, while the Seebeck coefficient and electrical conductivity of the material were retained. These properties, together with our large area fabrication approach, can provide an important route towards achieving high conversion efficiency, large area, and high scalable thermoelectric materials.

  8. Multiphysics multi-model simulation of large-area plasma chemical reactors

    NARCIS (Netherlands)

    Krzhizhanovskaya, V.; Ivanov, D.; Gorbachev, Y.; Smirnov, A.

    2010-01-01

    Facing an ever-growing demand for large-area solar cells and flat-panel displays, the industry strives to produce larger, cheaper and better performing thin films. Computer simulation has proved to be a reliable and cost-efficient way to optimize existing technologies, to develop and test new ideas.

  9. Multiphysics multi-model simulation of large-area plasma chemical reactors

    NARCIS (Netherlands)

    V. Krzhizhanovskaya; D. Ivanov; Y. Gorbachev; A. Smirnov

    2009-01-01

    Facing an ever-growing demand for large-area solar cells and flat-panel displays, the industry strives to produce larger, cheaper and better performing thin films. Computer simulation has proved to be a reliable and cost-efficient way to optimize existing technologies, to develop and test new ideas.

  10. High-throughput film-densitometry: An efficient approach to generate large data sets

    Energy Technology Data Exchange (ETDEWEB)

    Typke, Dieter; Nordmeyer, Robert A.; Jones, Arthur; Lee, Juyoung; Avila-Sakar, Agustin; Downing, Kenneth H.; Glaeser, Robert M.

    2004-07-14

    A film-handling machine (robot) has been built which can, in conjunction with a commercially available film densitometer, exchange and digitize over 300 electron micrographs per day. Implementation of robotic film handling effectively eliminates the delay and tedium associated with digitizing images when data are initially recorded on photographic film. The modulation transfer function (MTF) of the commercially available densitometer is significantly worse than that of a high-end, scientific microdensitometer. Nevertheless, its signal-to-noise ratio (S/N) is quite excellent, allowing substantial restoration of the output to ''near-to-perfect'' performance. Due to the large area of the standard electron microscope film that can be digitized by the commercial densitometer (up to 10,000 x 13,680 pixels with an appropriately coded holder), automated film digitization offers a fast and inexpensive alternative to high-end CCD cameras as a means of acquiring large amounts of image data in electron microscopy.

  11. Large-area WSe2 electric double layer transistors on a plastic substrate

    KAUST Repository

    Funahashi, Kazuma

    2015-04-27

    Due to the requirements for large-area, uniform films, currently transition metal dichalcogenides (TMDC) cannot be used in flexible transistor industrial applications. In this study, we first transferred chemically grown large-area WSe2 monolayer films from the as-grown sapphire substrates to the flexible plastic substrates. We also fabricated electric double layer transistors using the WSe2 films on the plastic substrates. These transistors exhibited ambipolar operation and an ON/OFF current ratio of ∼104, demonstrating chemically grown WSe2 transistors on plastic substrates for the first time. This achievement can be an important first step for the next-generation TMDC based flexible devices. © 2015 The Japan Society of Applied Physics.

  12. Structural and magnetic characterization of large area, free-standing thin films of magnetic ion intercalated dichalcogenides Mn0.25TaS2 and Fe0.25TaS2

    Science.gov (United States)

    Danz, Th; Liu, Q.; Zhu, X. D.; Wang, L. H.; Cheong, S. W.; Radu, I.; Ropers, C.; Tobey, R. I.

    2016-09-01

    Free-standing thin films of magnetic ion intercalated transition metal dichalcogenides are produced using ultramicrotoming techniques. Films of thicknesses ranging from 30 nm to 250 nm were achieved and characterized using transmission electron diffraction and x-ray magnetic circular dichroism. Diffraction measurements visualize the long range crystallographic ordering of the intercalated ions, while the dichroism measurements directly assess the orbital contributions to the total magnetic moment. We thus verify the unquenched orbital moment in Fe0.25TaS2 and measure the fully quenched orbital contribution in Mn0.25TaS2. Such films can be used in a wide variety of ultrafast x-ray and electron techniques that benefit from transmission geometries, and allow measurements of ultrafast structural, electronic, and magnetization dynamics in space and time.

  13. Solution-processed and low-temperature metal oxide n-channel thin-film transistors and low-voltage complementary circuitry on large-area flexible polyimide foil

    NARCIS (Netherlands)

    Rockelé, M.; Pham, D.V.; Steiger, J.; Botnaras, S.; Weber, D.; Vanfleteren, J.; Sterken, T.; Cuypers, D.; Steudel, S.; Myny, K.; Schols, S.; Putten, J.B.P.H. van der; Genoe, J.; Heremans, P.

    2012-01-01

    High-performance solution-based n-type metal oxide thin-film transistors (TFTs), fabricated directly on polyimide foil at a post-annealing temperature of only 250''C, are realized and reported. Saturation mobilities exceeding 2cmV(Vs) and on-to-off current ratios up to 10^ are achieved. The usage of

  14. Screening of high temperature adhesives for large area bonding

    Science.gov (United States)

    Stenersen, A. A.; Wykes, D. H.

    1980-01-01

    High temperature-resistant adhesive systems were screened for processability, mechanical and physical properties, operational capability at 589 K (600 F), and the ability to produce large area bonds of high quality in fabricating Space Shuttle components. The adhesives consisted primarily of polyimide systems, including FM34B-18, NR-150B2 (DuPont), PMR-15, LARC-13, LARC-160, Thermid 600, and AI-1130L (AMOCA). The processing studies included preparation of polyimide resins, fabrication of film adhesives, development of lay-up and cure procedures, fabrication of honeycomb sandwich panels, and fabrication of mid-plane bonded panels in joints up to 30.5 cm (12 in.) wide. The screening program included tests for tack and drape properties, reticulation and filleting characteristics, ability to produce void-free or low porosity bonds in mid-plane bonded panels, out-time stability, lap shear strength, climbing drum peel strength, and glass transition temperature (Tg). This paper describes the processing methods developed and the test results.

  15. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Directory of Open Access Journals (Sweden)

    T. Kimura

    2014-11-01

    Full Text Available Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene (PS-b-PEO diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  16. Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

    Science.gov (United States)

    Kimura, T.

    2014-11-01

    Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene) (PS-b-PEO) diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical) macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

  17. Very High Surface Area Mesoporous Thin Films of SrTiO3 Grown by Pulsed Laser Deposition and Application to Efficient Photoelectrochemical Water Splitting.

    Science.gov (United States)

    Sangle, Abhijeet L; Singh, Simrjit; Jian, Jie; Bajpe, Sneha R; Wang, Haiyan; Khare, Neeraj; MacManus-Driscoll, Judith L

    2016-12-14

    Very high surface area, self-assembled, highly crystalline mesoporous SrTiO3 (STO) thin films were developed for photoelectrochemical water splitting. Much improved performance of these mesoporous films compared to planar STO thin films and any other form of STO such as single crystal samples and nanostructures was demonstrated. The high performance resulted from very large surface area films and optimization of carrier concentration.

  18. Large-Area Laser-Lift-Off Processing in Microelectronics

    Science.gov (United States)

    Delmdahl, R.; Pätzel, R.; Brune, J.

    Laser lift-off is an enabling technology for microelectronics growth markets such as light emitting diodes, densely packaged semiconductor devices, and flexible displays. For example, thin film transistor structures fabricated on top of polymer layers spun on glass carriers must be delaminated from rigid substrates to create lightweight and rugged flexible displays on polymers. Low-thermal-budget processes are generically required to protect adjacent functional films. Excimer lasers provide short UV wavelength and short pulse duration required for highly-localized energy coupling. The high output power of excimer lasers enables a large processing footprint and the high-throughput rates needed in mass manufacturing.

  19. Large-area thermoelectric high-aspect-ratio nanostructures by atomic layer deposition

    Science.gov (United States)

    Ruoho, Mikko; Juntunen, Taneli; Tittonen, Ilkka

    2016-09-01

    We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m-1 K-1 while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator. The wall thickness of the fabricated nanotubes was varied within a range of up to 100 nm. The samples show polycrystalline nature with (002) preferred crystal orientation.

  20. Porous La0.6Sr0.4CoO3-δ thin film cathodes for large area micro solid oxide fuel cell power generators

    DEFF Research Database (Denmark)

    Garbayo, A.; Esposito, Vincenzo; Sanna, Simone

    2014-01-01

    Porous La0.6Sr0.4CoO3-δ thin films were fabricated by pulsed laser deposition for being used as a cathode for micro solid oxide fuel cell applications as MEMS power generators. Symmetrical La0.6Sr0.4CoO3-δ/ yttria-stabilized zirconia/La0.6Sr0.4CoO3-δ free-standing membranes were fabricated using ...

  1. Large-area single-mode photonic bandgap vcsels

    DEFF Research Database (Denmark)

    Birkedal, Dan; Gregersen, N.; Bischoff, S.;

    2003-01-01

    We demonstrate that the photonic bandgap effect can be used to control the modes of large area vertical cavity surface emitting lasers. We obtain more than 20 dB side mode suppression ratios in a 10-micron area device.......We demonstrate that the photonic bandgap effect can be used to control the modes of large area vertical cavity surface emitting lasers. We obtain more than 20 dB side mode suppression ratios in a 10-micron area device....

  2. Low-Temperature Soft-Cover Deposition of Uniform Large-Scale Perovskite Films for High-Performance Solar Cells.

    Science.gov (United States)

    Ye, Fei; Tang, Wentao; Xie, Fengxian; Yin, Maoshu; He, Jinjin; Wang, Yanbo; Chen, Han; Qiang, Yinghuai; Yang, Xudong; Han, Liyuan

    2017-07-14

    Large-scale high-quality perovskite thin films are crucial to produce high-performance perovskite solar cells. However, for perovskite films fabricated by solvent-rich processes, film uniformity can be prevented by convection during thermal evaporation of the solvent. Here, a scalable low-temperature soft-cover deposition (LT-SCD) method is presented, where the thermal convection-induced defects in perovskite films are eliminated through a strategy of surface tension relaxation. Compact, homogeneous, and convection-induced-defects-free perovskite films are obtained on an area of 12 cm(2) , which enables a power conversion efficiency (PCE) of 15.5% on a solar cell with an area of 5 cm(2) . This is the highest efficiency at this large cell area. A PCE of 15.3% is also obtained on a flexible perovskite solar cell deposited on the polyethylene terephthalate substrate owing to the advantage of presented low-temperature processing. Hence, the present LT-SCD technology provides a new non-spin-coating route to the deposition of large-area uniform perovskite films for both rigid and flexible perovskite devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Fabrication of large area homogeneous metallic nanostructures for optical sensing using colloidal lithography

    DEFF Research Database (Denmark)

    Eriksen, René Lynge; Pors, Anders; Dreier, Jes;

    2010-01-01

    We propose a simple and reproducible method for fabricating large area metal films with inter-connected nanostructures using a combination of colloidal lithography, metal deposition and a template stripping technique. The method is generic in the sense that it is possible to produce a variety...... to fabricate metal films with inter-connected nanostructures consisting of either partial spherical shells or the inverted structures: spherical cavities. The substrates are characterized by optical reflectance and transmittance spectroscopy. We demonstrate, in the case of partial spherical shells...

  4. Metal-Oxide Film Conversions Involving Large Anions

    Energy Technology Data Exchange (ETDEWEB)

    Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C. [The University of Western Ontario, Chemistry Department, 1151 Richmond St., N6A 5B7, London, Ontario (Canada)

    2008-07-01

    The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I{sup -}, Br{sup -}, S{sup 2-}). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag{sub 2}O to (1) AgI and (2) AgBr. (authors)

  5. Large area modules based on low band gap polymers

    DEFF Research Database (Denmark)

    Bundgaard, Eva; Krebs, Frederik C

    2010-01-01

    The use of three low band gap polymers in large area roll-to-roll coated modules is demonstrated. The polymers were prepared by a Stille cross coupling polymerization and all had a band gap around 1.6 eV. The polymers were first tested in small area organic photovoltaic devices which showed...... efficiencies from 0.4 to 2 %. Then large area roll-to-roll coated modules were processed and these showed efficiencies up to 0.6 %. It is clear that further study is necessary before this type of polymer is competitive with P3HT in large area modules....

  6. Selective-Area Growth of Thick Diamond Films Using Chemically Stable Masks of Ru/Au and Mo/Au

    Science.gov (United States)

    Nagase, Masanori; Watanabe, Katsumi; Umezawa, Hitoshi; Shikata, Shinichi

    2012-07-01

    Selective-area growth of diamond films in microwave-plasma chemical vapor deposition was performed using newly developed masks. By forming chemically stable masks made of Ru/Au or Mo/Au, which have high melting points, good adhesion to diamond, and difficulty in forming carbide compounds, patterned diamond films with a large thickness of 50 µm, a large area of 5 mm2, and a high orientation in the [001] direction were successfully grown on (001) diamond substrates without degradation of the crystal quality of masked areas.

  7. Plasma deposited diamond-like carbon films for large neutralarrays

    Energy Technology Data Exchange (ETDEWEB)

    Brown, I.G.; Blakely, E.A.; Bjornstad, K.A.; Galvin, J.E.; Monteiro, O.R.; Sangyuenyongpipat, S.

    2004-07-15

    To understand how large systems of neurons communicate, we need to develop methods for growing patterned networks of large numbers of neurons. We have found that diamond-like carbon thin films formed by energetic deposition from a filtered vacuum arc carbon plasma can serve as ''neuron friendly'' substrates for the growth of large neural arrays. Lithographic masks can be used to form patterns of diamond-like carbon, and regions of selective neuronal attachment can form patterned neural arrays. In the work described here, we used glass microscope slides as substrates on which diamond-like carbon was deposited. PC-12 rat neurons were then cultured on the treated substrates and cell growth monitored. Neuron growth showed excellent contrast, with prolific growth on the treated surfaces and very low growth on the untreated surfaces. Here we describe the vacuum arc plasma deposition technique employed, and summarize results demonstrating that the approach can be used to form large patterns of neurons.

  8. Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

    Science.gov (United States)

    Copic, Davor; Hart, A John

    2015-04-22

    High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design.

  9. Large-area, high-quality monolayer graphene from polystyrene at atmospheric pressure

    Science.gov (United States)

    Xu, Junqi; Fu, Can; Sun, Haibin; Meng, Lanxiang; Xia, Yanjie; Zhang, Chongwu; Yi, Xiaolei; Yang, Wenchao; Guo, Pengfei; Wang, Chunlei; Liu, Jiangfeng

    2017-04-01

    Graphene films have been attracting great interest owing to their unique physical properties. In this paper, we develop an efficient method to prepare large-area monolayer graphene (97.5% coverage) by atmospheric pressure chemical vapor deposition on Cu foils using polystyrene in a short time (3 min). Raman spectroscopy, transmission electron microscopy and scanning electron microscopy are employed to confirm the thickness and uniformity of the graphene films. Graphene films on glass substrates show high optical transmittance and electrical conductivity. Magnetic transport studies demonstrate that the as-grown monolayer graphene exhibits a high carrier mobility of 3395 cm2 V‑1 s‑1 at 25 K. On the basis of the analysis, it is concluded that our method is a simple, safe and versatile approach for the synthesis of monolayer graphene.

  10. Study of Preparation of Large Area Standard Source

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    With increasingly widespread application of nuclear technology, many large area contamination detectors are used to measure the contaminated surface by α, β radionuclides in nuclear facilities and isotope production places. To solve the

  11. Spectroscopic study of low pressure, low temperature H2-CH4-CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films. Part II: on plasma chemical processes

    Science.gov (United States)

    Nave, A. S. C.; Baudrillart, B.; Hamann, S.; Bénédic, F.; Lombardi, G.; Gicquel, A.; van Helden, J. H.; Röpcke, J.

    2016-12-01

    In a distributed antenna array (DAA) reactor, microwave H2 plasmas with admixtures of 2.5% CH4 and 1% CO2 used for the deposition of nanocrystalline diamond films have been studied by infrared laser absorption and optical emission spectroscopy (OES) techniques. The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and pressure at relatively low pressures, up to 0.55 mbar, and power values, up to 3 kW. The evolution of the concentration of the methyl radical, CH3, of five stable molecules, CH4, CO2, CO, C2H2 and C2H6, and of vibrationally excited CO in the first and second hot band was monitored in the plasma processes by in situ infrared laser absorption spectroscopy using tunable lead salt diode lasers (TDL) and an external-cavity quantum cascade laser (EC-QCL) as radiation sources. OES was applied simultaneously to obtain complementary information about the degree of dissociation of the H2 precursor and of its gas temperature. The experimental results are presented in two separate parts. In Part I, the first paper in a two-part series, the measurement of the gas (T gas), rotational (T rot) and vibrational (T vib) temperatures of the various species in the complex plasma was the main focus of interest. Depending on the different plasma zones the gas temperature was found to range between about 360 and 1000 K inside the DAA reactor (Nave et al 2016 Plasma Sources Sci. Technol. 25 065002). In Part II, the present paper, taking into account the temperatures determined in the first paper, the concentrations of the various species, which were found to be in a range between 1011 and 1015 cm-3, are the focus of interest. The influence of the discharge parameters power and pressure on the molecular concentrations has been studied. To achieve further insight into general plasma chemical aspects the dissociation of the carbon precursor gases including their fragmentation and conversion to the reaction products has been

  12. Spectroscopic study of low pressure, low temperature H2-CH4-CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films. Part I: on temperature determination and energetic aspects

    Science.gov (United States)

    Nave, A. S. C.; Baudrillart, B.; Hamann, S.; Bénédic, F.; Lombardi, G.; Gicquel, A.; van Helden, J. H.; Röpcke, J.

    2016-12-01

    In a distributed antenna array (DAA) reactor, microwave H2 plasmas with admixtures of 2.5% CH4 and 1% CO2 used for the deposition of nanocrystalline diamond films have been studied by infrared absorption and optical emission spectroscopy (OES) techniques. The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and pressure at relatively low pressures, up to 0.55 mbar, and power values, up to 3 kW. The evolution of the concentration of the methyl radical, CH3, and of five stable molecules, CH4, CO2, CO, C2H2 and C2H6, was monitored in the plasma processes by in situ infrared laser absorption spectroscopy using lead salt diode lasers (TDL) and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. OES was applied simultaneously to obtain complementary information about the degree of dissociation of the H2 precursor gas and of its gas temperature. The experimental results are presented in two separate parts. In Part I, the present paper, the measurement of the gas (T gas), rotational (T rot) and vibrational (T vib) temperatures of the various species in the complex plasma was the main focus of interest. To achieve reliable values for the gas temperature inside and outside the plasma bulk as well as for the rotational and vibrational temperatures in the plasma hot zones, which are of great importance for calculation of species concentrations, five different methods based on the emission and absorption spectroscopy data of H2, CH4, CH3 and CO have been used. In these, line profile analysis has been combined with Boltzmann plot methods. Based on the wide tuning range of the EC-QCL, a variety of CO lines in the ground and three excited states was measured enabling extensive temperature analysis providing new insight into the energetic aspects of this multi-component plasma. Depending on the different plasma zones the gas temperature was found to range between about 360 and 1000 K inside the DAA reactor

  13. Satellite image collection modeling for large area hazard emergency response

    Science.gov (United States)

    Liu, Shufan; Hodgson, Michael E.

    2016-08-01

    Timely collection of critical hazard information is the key to intelligent and effective hazard emergency response decisions. Satellite remote sensing imagery provides an effective way to collect critical information. Natural hazards, however, often have large impact areas - larger than a single satellite scene. Additionally, the hazard impact area may be discontinuous, particularly in flooding or tornado hazard events. In this paper, a spatial optimization model is proposed to solve the large area satellite image acquisition planning problem in the context of hazard emergency response. In the model, a large hazard impact area is represented as multiple polygons and image collection priorities for different portion of impact area are addressed. The optimization problem is solved with an exact algorithm. Application results demonstrate that the proposed method can address the satellite image acquisition planning problem. A spatial decision support system supporting the optimization model was developed. Several examples of image acquisition problems are used to demonstrate the complexity of the problem and derive optimized solutions.

  14. Acrolein Microspheres Are Bonded To Large-Area Substrates

    Science.gov (United States)

    Rembaum, Alan; Yen, Richard C. K.

    1988-01-01

    Reactive cross-linked microspheres produced under influence of ionizing radiation in aqueous solutions of unsaturated aldehydes, such as acrolein, with sodium dodecyl sulfate. Diameters of spheres depend on concentrations of ingredients. If polystyrene, polymethylmethacrylate, or polypropylene object immersed in solution during irradiation, microspheres become attached to surface. Resulting modified surface has grainy coating with reactivity similar to free microspheres. Aldehyde-substituted-functional microspheres react under mild conditions with number of organic reagents and with most proteins. Microsphere-coated macrospheres or films used to immobilize high concentrations of proteins, enzymes, hormones, viruses, cells, and large number of organic compounds. Applications include separation techniques, clinical diagnostic tests, catalytic processes, and battery separators.

  15. Status of large area CsI photocathode developments

    CERN Document Server

    Schyns, E M

    2002-01-01

    The development of large area reflective CsI photocathodes for RICH detectors is reviewed in the context of their production process and their performance. The quantum efficiencies of six large photocathodes recently produced by ALICE are compared with results available from the large photocathodes at HADES and STAR and with earlier R&D results obtained on small area samples. The CsI coating parameters and new developments in the domain of the production and the preparation of substrates are discussed in relation with the photocathode performance. (24 refs).

  16. Modal instabilities in very large mode area rod fiber amplifiers

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Hansen, Kristian Rymann; Laurila, Marko

    large core fiber areas are highly desirable to mitigate various nonlinear processes, such as Kerr, four-wave mixing, Raman, and Brillouin effects. It is difficult to scale up the core area without going into a multi-moded regime. Microstructured fiber technology has allowed core diameters of 60...... to modal instability [3-5], represented in Fig. 2 as the growth of the higher order mode content. This is a fundamental obstacle for power scaling in fiber amplifiers that significantly reduces beam quality and stability. We combine analytic considerations for thermally induced mode coupling...... with the finite element method to allow complex micro structured fibers to be considered. Thereby the modal instability threshold is estimated for very large mode area fiber amplifiers of various photonic crystal fiber designs. Experimentally the modal instability threshold for very large mode area fiber...

  17. Synthesis and characterization of large-grain solid-phase crystallized polycrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avishek, E-mail: avishek.kumar@nus.edu.sg, E-mail: dalapatig@imre.a-star.edu.sg [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Law, Felix; Widenborg, Per I. [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 (Singapore); Dalapati, Goutam K., E-mail: avishek.kumar@nus.edu.sg, E-mail: dalapatig@imre.a-star.edu.sg; Subramanian, Gomathy S.; Tan, Hui R. [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Aberle, Armin G. [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 and Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore)

    2014-11-01

    n-type polycrystalline silicon (poly-Si) films with very large grains, exceeding 30 μm in width, and with high Hall mobility of about 71.5 cm{sup 2}/V s are successfully prepared by the solid-phase crystallization technique on glass through the control of the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio. The effect of this gas flow ratio on the electronic and structural quality of the n-type poly-Si thin film is systematically investigated using Hall effect measurements, Raman microscopy, and electron backscatter diffraction (EBSD), respectively. The poly-Si grains are found to be randomly oriented, whereby the average area weighted grain size is found to increase from 4.3 to 18 μm with increase of the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio. The stress in the poly-Si thin films is found to increase above 900 MPa when the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio is increased from 0.025 to 0.45. Finally, high-resolution transmission electron microscopy, high angle annular dark field-scanning tunneling microscopy, and EBSD are used to identify the defects and dislocations caused by the stress in the fabricated poly-Si films.

  18. Self-formation of sub-60-nm half-pitch gratings with large areas through fracturing

    Science.gov (United States)

    Pease, Leonard F.; Deshpande, Paru; Wang, Ying; Russel, William B.; Chou, Stephen Y.

    2007-09-01

    Periodic micro- and nanostructures (gratings) have many significant applications in electronic, optical, magnetic, chemical and biological devices and materials. Traditional methods for fabricating gratings by writing with electrons, ions or a mechanical tip are limited to very small areas and suffer from extremely low throughput. Interference lithography can achieve relatively large fabrication areas, but has a low yield for small-period gratings. Photolithography, nanoimprint lithography, soft lithography and lithographically induced self-construction all require a prefabricated mask, and although electrohydrodynamic instabilities can self-produce periodic dots without a mask, gratings remain challenging. Here, we report a new low-cost maskless method to self-generate nano- and microgratings from an initially featureless polymer thin film sandwiched between two relatively rigid flat plates. By simply prising apart the plates, the film fractures into two complementary sets of nonsymmetrical gratings, one on each plate, of the same period. The grating period is always four times the thickness of the glassy film, regardless of its molecular weight and chemical composition. Periods from 120 nm to 200 µm have been demonstrated across areas as large as two square centimetres.

  19. Large-area, uniform white light LED source on a flexible substrate.

    Science.gov (United States)

    Sher, Chin-Wei; Chen, Kuo-Ju; Lin, Chien-Chung; Han, Hau-Vei; Lin, Huang-Yu; Tu, Zong-Yi; Tu, Hsien-Hao; Honjo, Keiji; Jiang, Hsin-Yi; Ou, Sin-Liang; Horng, Ray-Hua; Li, Xiuling; Fu, Chien-Chung; Kuo, Hao-Chung

    2015-09-21

    This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications.

  20. Molecular beam epitaxy of large-area SnSe2 with monolayer thickness fluctuation

    Science.gov (United States)

    Park, Young Woon; Jerng, Sahng-Kyoon; Jeon, Jae Ho; Roy, Sanjib Baran; Akbar, Kamran; Kim, Jeong; Sim, Yumin; Seong, Maeng-Je; Kim, Jung Hwa; Lee, Zonghoon; Kim, Minju; Yi, Yeonjin; Kim, Jinwoo; Noh, Do Young; Chun, Seung-Hyun

    2017-03-01

    The interest in layered materials is largely based on the expectation that they will be beneficial for a variety of applications, from low-power-consuming, wearable electronics to energy harvesting. However, the properties of layered materials are highly dependent on thickness, and the difficulty of controlling thickness over a large area has been a bottleneck for commercial applications. Here, we report layer-by-layer growth of SnSe2, a layered semiconducting material, via van der Waals epitaxy. The films were fabricated on insulating mica substrates with substrate temperatures in the range of 210 °C-370 °C. The surface consists of a mixture of N and (N ± 1) layers, showing that the thickness of the film can be defined with monolayer accuracy (±0.6 nm). High-resolution transmission electron microscopy reveals a polycrystalline film with a grain size of ˜100 nm and clear Moiré patterns from overlapped grains with similar thickness. We also report field effect mobility values of 3.7 cm2 V-1 s-1 and 6.7 cm2 V-1 s-1 for 11 and 22 nm thick SnSe2, respectively. SnSe2 films with customizable thickness can provide valuable platforms for industry and academic researchers to fully exploit the potential of layered materials.

  1. Magnetic Property in large array cobalt antidot thin film using polymer-assisted nanosphere lithography

    Science.gov (United States)

    Lee, Wei-Li; Ho, Chi-Chih; Hsieh, Yung-Wu; Juan, Wen-Tau; Lin, Keng-Hui

    2010-03-01

    We have developed a new method to prepare monolayer of close- packed nanospheres (NSs) over large area onto a substrate of any kind utilizing polymer bridging effect. The NSs packing domain can be as large as 1 cmx1 cm which is demonstrated from its diffraction pattern. It was then used as a template to fabricate series of cobalt antidot thin films with different antidot diameter ranging from 100nm to 180nm. Because of the good periodicity and less defects in our nanostructured samples, we would be able to not only qualitatively study their magnetic properties but also quantitatively. As the antidot diameter increases, the surface to bulk volume fraction increases and the surface magnetism becomes more prominent. We found a systematic increase in magnetic coercivity with the antidote diameter, while the saturation magnetization drops at large antidote diameter. Detailed analysis and their implication will be discussed.

  2. Large-area metallic photonic lattices for military applications.

    Energy Technology Data Exchange (ETDEWEB)

    Luk, Ting Shan

    2007-11-01

    In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.

  3. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  4. Dispersion flattened single mode optical fiber with large effective area

    Science.gov (United States)

    Babita, Rastogi, Vipul

    2013-06-01

    In this paper we present design of a fiber having ultra-flattened dispersion with large effective area over a wide range of wavelengths. The maximum value of the dispersion and dispersion slope within the spectral range 1450-1600 nm are 1.0 ps/km/nm and 0.05 ps/km/nm2 respectively. Effective mode area within the aforementioned wavelength range varies from 100-295 μm2.

  5. Modeling a Dry Etch Process for Large-Area Devices

    Energy Technology Data Exchange (ETDEWEB)

    Buss, R.J.; Hebner, G.A.; Ruby, D.S.; Yang, P.

    1999-07-28

    There has been considerable interest in developing dry processes which can effectively replace wet processing in the manufacture of large area photovoltaic devices. Environmental and health issues are a driver for this activity because wet processes generally increase worker exposure to toxic and hazardous chemicals and generate large volumes of liquid hazardous waste. Our work has been directed toward improving the performance of screen-printed solar cells while using plasma processing to reduce hazardous chemical usage.

  6. Electronic Hybridization of Large-Area Stacked Graphene Films

    Science.gov (United States)

    2013-01-01

    Roth , S.; et al. Raman Spectrum of Graphene and Graphene Layers. Phys. Rev. Lett. 2006, 97, 187401. 25. Yang, L.; Deslippe, J.; Park, C.-H.; Cohen, M. L...Y.; Wu, Y.; Lui, C. H.; Misewich, J. A.; Heinz , T. F. Measurement of the Optical Conductivity of Graphene. Phys. Rev. Lett. 2008, 101, 196405. 27

  7. Large-area uniform electron doping of graphene by Ag nanofilm

    Directory of Open Access Journals (Sweden)

    Xiaopeng Guo

    2017-04-01

    Full Text Available Graphene has attracted much attention at various research fields due to its unique optical, electronic and mechanical properties. Up to now, graphene has not been widely used in optoelectronic fields due to the lack of large-area uniform doped graphene (n-doped and p-doped with smooth surface. Therefore, it is rather desired to develop some effective doping methods to extend graphene to optoelectronics. Here we developed a novel doping method to prepare large-area (> centimeter scale uniform doped graphene film with a nanoscale roughness(RMS roughness ∼1.4 nm, the method (nano-metal film doping method is simple but effective. Using this method electron doping (electron-injection may be easily realized by the simple thermal deposition of Ag nano-film on a transferred CVD graphene. The doping effectiveness has been proved by Raman spectroscopy and spectroscopic ellipsometry. Importantly, our method sheds light on some potential applications of graphene in optoelectronic devices such as photodetectors, LEDs, phototransistors, solar cells, lasers etc.

  8. Large Sky Area Multi-Object Fiber Spectroscopic Telescope

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yongheng

    2011-01-01

    The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is a meridian reflecting Schmidt telescope with a clear aperture of four meters, a focal length of 20 meters and a field of view of five degrees. By using active optics technique to control its reflecting corrector, the LAMOST is made a unique astronomical instrument in combining a large aperture with a wide field of view. The available large focal plane of 1.75 meter in diameter can accommodate up to 4,000 fibers,

  9. Structural evolution of Ti destroyable interlayer in large-size diamond film deposition by DC arc plasma jet

    Science.gov (United States)

    Guo, Jianchao; Li, Chengming; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Hua, Chenyi; Yan, Xiongbo

    2016-05-01

    The addition of titanium (Ti) interlayer was verified to reduce the residual stress of diamond films by self-fracturing and facilitate the harvest of a crack-free free-standing diamond film prepared by direct current (DC) arc plasma jet. In this study, the evolution of the Ti interlayer between large-area diamond film and substrate was studied and modeled in detail. The evolution of the interlayer was found to be relevant to the distribution of the DC arc plasma, which can be divided into three areas (arc center, arc main, and arc edge). The formation rate of titanium carbide (TiC) in the arc main was faster than in the other two areas and resulted in the preferred generation of crack in the diamond film in the arc main during cooling. Sandwich structures were formed along with the growth of TiC until the complete transformation of the Ti interlayer. The interlayer released stress via self-fracture. Avoiding uneven fragile regions that formed locally in the interlayer and achieving cooperatively released stress are crucial for the preparation of large crack-free diamond films.

  10. Electron Emission from Ultra-Large Area MOS Electron Emitters

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm;

    2009-01-01

    Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1 cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (~5 nm), a Ti wetting layer (3–10 Å), and a Au top layer (5–60 nm). Electron emission from...... layer is varied from 3 to 10 Å which changes the emission efficiency by more than one order of magnitude. The apparent mean free path of ~5 eV electrons in Au is found to be 52 Å. Deposition of Cs on the Au film increased the electron emission efficiency to 4.3% at 4 V by lowering the work function....... Electron emission under high pressures (up to 2 bars) of Ar was observed. ©2009 American Vacuum Society...

  11. Polarization maintaining large-mode area photonic crystal fibre

    DEFF Research Database (Denmark)

    Folkenberg, Jacob Riis; Nielsen, Martin Dybendal; Mortensen, N.A.

    2004-01-01

    We report on a polarization maintaining large mode area photonic crystal fiber. Unlike, previous work on polarization maintaining photonic crystal fibers, birefringence is introduced using stress applying parts. This has allowed us to realize fibers, which are both single mode at any wavelength a...

  12. On large area LIPSS coverage by multiple pulses

    Science.gov (United States)

    Reif, Juergen; Martens, Christian; Uhlig, Sebastian; Ratzke, Markus; Varlamova, Olga; Valette, Stephane; Benayoun, Stephane

    2015-05-01

    The phenomenon of covering large areas with coherent LIPSS produced by multiple, adjacent spots is investigated by varying spot overlap and irradiation dose per spot. In contrast to the typical experimental arrangement, the linear traces of spots were produced by discontinuously advancing the sample between the individual spots. We show that even with almost no overlap the LIPSS patterns appear to be coherently connected.

  13. Inkjet technology for large-area OPV applications

    NARCIS (Netherlands)

    Ren, M.; Sweelssen, J.; Andriessen, H.A.J.M.

    2011-01-01

    The roll-to-roll manufacturing process is believed to significantly reduce the cost-price of large area organic photovoltaic systems. Therefore, we build up knowledge base concerning the influence of process conditions on the performance of polymer solar cells. Inkjet printing has been a major resea

  14. Plastic film materials for dosimetry of very large absorbed doses

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne; Abdel-Rahim, F.

    1985-01-01

    Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up...... to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response at such high doses are polyethylene terephthalate, high-density polyethylene, dyed polyvinylchloride...

  15. Library Resources in Special Areas of Music: Film Music.

    Science.gov (United States)

    Wright, H. Stephen

    Intended as an orientation for music librarians unfamiliar with the film music field, this presentation addresses the most common film music questions received from library patrons, including queries about composers, soundtrack albums, the subject of the music, and scores, and describes the basic film music reference sources to consult for…

  16. Sputtering of thin benzene films by large noble gas clusters

    Energy Technology Data Exchange (ETDEWEB)

    Rzeznik, L. [Jagiellonian University, Smoluchowski Institute of Physics, Reymonta 4, 30-059 Krakow (Poland)], E-mail: lukasz.rzeznik@uj.edu.pl; Czerwinski, B.; Paruch, R. [Jagiellonian University, Smoluchowski Institute of Physics, Reymonta 4, 30-059 Krakow (Poland); Garrison, B.J. [Pennsylvania State University, Department of Chemistry, 104 Chemistry Bldg, University Park, PA 16802 (United States); Postawa, Z. [Jagiellonian University, Smoluchowski Institute of Physics, Reymonta 4, 30-059 Krakow (Poland)

    2009-05-01

    Molecular dynamics computer simulations have been employed to investigate the sputtering process of a benzene (C{sub 6}H{sub 6}) monolayer deposited on Ag{l_brace}1 1 1{r_brace} induced by an impact of slow clusters composed of large number of noble gas atoms. The sputtering yield, surface modifications, and the kinetic energy distributions of ejected species have been analyzed as a function of the cluster size and the binding energy of benzene to the Ag substrate. It is shown that high- and low-energy components can be identified in the kinetic energy distributions of ejected molecules. The mechanistic analysis of calculated trajectories reveals that high-energy molecules are emitted by direct interaction with projectile atoms that are backreflected from the metal substrate. Most of the molecules are ejected by this process. Low-energy molecules are predominantly emitted by a recovering action of the substrate deformed by the impact of a massive cluster. The increase of the binding energy leads to attenuation of both high- and low-energy ejection channels. However, low-energy ejection is particularly sensitive to the variation of this parameter. The area of the molecular overlayer sputtered by the projectile impact is large and increases with the cluster size and the kinetic energy of the projectile. Also the size and the shape of this area are sensitive to the changes of the binding energy. The radius of the sputtered region decreases, and its shape changes from almost circular to a ring-like zone when the binding energy is increased. Some predictions about the perspectives of the application of large clusters in the organic secondary ion mass spectrometry are discussed.

  17. Fire-on-fire interactions in three large wilderness areas

    Science.gov (United States)

    Teske, Casey C.

    Current knowledge about wildfire occurrence is not complete. Fire researchers and managers hold the assumption that previous wildfires affect subsequent wildfires; however, research regarding the interactions of large wildfires at their common boundaries is missing from the literature. This research focuses on understanding the influence of previous large wildfires on subsequent large wildfires in three wilderness areas: The Greater Bob Marshall, the Selway-Bitterroot, and the Frank Church. Data from the Monitoring Trends in Burn Severity (MTBS) project, which mapped large wildfires in the western United States occurring since 1984, are used for the research. The combination of using wilderness areas and remotely sensed images allows an objective and consistent analysis of fire-on-fire interaction that is extensive in both time and space. Standardized methods for analyzing fire interactions do not currently exist, therefore methods were developed, tested, and refined to describe, quantify, and compare once-burned and re-burned locations within a subset of ten fires in terms of size, location, timing between fires, and severity. These methods were then used to address the question of whether re-burns occur within each of the three wilderness areas. Edge and re-burn characteristics were also derived and quantified. Results were statistically and empirically compared to randomized fire intersections and to published fire history research for each area. Although a low proportion of each study area burns or re-burns, when a new fire encounters a previous fire it re-burns onto the previously burned area approximately 80% of the time. Current large wildfires are behaving in a typical fashion, although on some landscapes the amount of re-burn is not different from what would be expected due to chance. Lastly, the complexity of the post-fire landscape was assessed using texture metrics. Pre-fire and post-fire landscapes were shown to be different, with post-fire landscapes

  18. Photocurrent enhancement by surface plasmon resonance of gold nanoparticles in spray deposited large area dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chander, Nikhil; Singh, Puneet [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India); Khan, A.F. [Department of Electronics and Information Technology, Ministry of Communications and Information Technology, Government of India, New Delhi 110003 (India); Dutta, Viresh [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India); Komarala, Vamsi K., E-mail: vamsi@ces.iitd.ac.in [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2014-10-01

    A facile method for fabricating large area TiO{sub 2} and TiO{sub 2}–Au nanocomposite films for dye sensitized solar cells (DSSCs) is presented using a spray technique. Pre-synthesized gold nanoparticles (Au NPs) were sprayed together with the TiO{sub 2} NPs and composite films with brilliant coloration due to surface plasmon resonances of Au NPs were prepared. Composite films containing ∼ 15 nm sized Au NPs exhibited enhanced absorption in the visible region of the electromagnetic spectrum. DSSCs with a large area of ∼ 4.5 cm{sup 2} were fabricated and a photocurrent enhancement of ∼ 10% was obtained for plasmonic DSSC containing 0.3 wt.% of ∼ 15 nm Au NPs. Incident photon to current conversion efficiency data conclusively showed enhanced currents in the visible region of the polychromatic spectrum arising due to plasmon enhanced near-field effects of Au NPs around the absorbing dye molecules. - Highlights: • Preparation of TiO{sub 2} and TiO{sub 2}–Au films with a large area of ∼ 7.5 cm{sup 2} by a spray technique • An efficiency of ∼ 4.5% achieved by the large area plasmonic DSSC • Photocurrent enhancement due to SPR effects of gold NPs observed • Comparison of the spray and conventional doctor blade methods in DSSC performance • Demonstration of technological feasibility and versatility of a simple spray process.

  19. Conformal Electroplating of Azobenzene-Based Solar Thermal Fuels onto Large-Area and Fiber Geometries.

    Science.gov (United States)

    Zhitomirsky, David; Grossman, Jeffrey C

    2016-10-05

    There is tremendous growth in fields where small functional molecules and colloidal nanomaterials are integrated into thin films for solid-state device applications. Many of these materials are synthesized in solution and there often exists a significant barrier to transition them into the solid state in an efficient manner. Here, we develop a methodology employing an electrodepositable copolymer consisting of small functional molecules for applications in solar energy harvesting and storage. We employ azobenzene solar thermal fuel polymers and functionalize them to enable deposition from low concentration solutions in methanol, resulting in uniform and large-area thin films. This approach enables conformal deposition on a variety of conducting substrates that can be either flat or structured depending on the application. Our approach further enables control over film growth via electrodepsition conditions and results in highly uniform films of hundreds of nanometers to microns in thickness. We demonstrate that this method enables superior retention of solar thermal fuel properties, with energy densities of ∼90 J/g, chargeability in the solid state, and exceptional materials utilization compared to other solid-state processing approaches. This novel approach is applicable to systems such as photon upconversion, photovoltaics, photosensing, light emission, and beyond, where small functional molecules enable solid-state applications.

  20. Homogenous Crack-Free Large Size YBCO/YSZ/Sapphire Films for Application

    Science.gov (United States)

    Almog, B.; Azoulay, M.; Deutscher, G.

    2006-09-01

    YBa2Cu3O7-δ (YBCO) films grown on Sapphire are highly suitable for applications. The production of large size (2-3″) homogeneous, thick (d ⩾ 600nm) films of high quality is of major importance. We report the growth of such films using a buffer layer of Yttrium-stabilized ZrO2(YSZ). The films are highly homogeneous and show excellent mechanical properties. They exhibit no sign of cracking even after many thermal cycles. Their critical thickness exceeds 1000nm. However, because of the large lattice mismatch there is a decrease in the electric properties(increases Rs, decreases jc).

  1. Vision measurement method of object position in large remote area

    Science.gov (United States)

    Liu, Meilian; Li, Kejie; Cai, Huimin; Zhu, Wei

    2011-08-01

    In order to measure accurately position of object in remote large area with vision measurement method, a special layout of vision measurement system was designed. Some calibration objects which have the same height with cameras were placed at specific position in the measurement area. By adjusting carefully the posture of cameras, those calibration objects were imaged at the same pixel row which contained the camera principal point. As a result, the master planes of cameras which were determined by the pixel row which contained the principal point and the optical axis of cameras were horizontal and coplanar. So, the u pixel coordinate of any space point was same with the one of its projection point in the xoy coordinate plane and a simplified calculation model was derived. Compared with the traditional vision measurement method, this method is simpler and more suitable for large remote area measurement. In order to verify the validity of this method, a verification experiment had been made. The experimental results show that the resolving accuracy of this model is very high, and this measurement method is very good to meet the requirement of large remote area measurement.

  2. Large-area, laterally-grown epitaxial semiconductor layers

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jung; Song, Jie; Chen, Danti

    2017-07-18

    Structures and methods for confined lateral-guided growth of a large-area semiconductor layer on an insulating layer are described. The semiconductor layer may be formed by heteroepitaxial growth from a selective growth area in a vertically-confined, lateral-growth guiding structure. Lateral-growth guiding structures may be formed in arrays over a region of a substrate, so as to cover a majority of the substrate region with laterally-grown epitaxial semiconductor tiles. Quality regions of low-defect, stress-free GaN may be grown on silicon.

  3. On large area LIPSS coverage by multiple pulses

    Energy Technology Data Exchange (ETDEWEB)

    Reif, Juergen, E-mail: reif@tu-cottbus.de [Brandenburgische Technische Universität BTU Cottbus-Senftenberg, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Martens, Christian; Uhlig, Sebastian; Ratzke, Markus; Varlamova, Olga [Brandenburgische Technische Universität BTU Cottbus-Senftenberg, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Valette, Stephane; Benayoun, Stephane [LTDS, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully Cedex (France)

    2015-05-01

    Graphical abstract: - Highlights: • Ripples coherence for both overlapping and separated spots. • Grooves coherence for both overlapping and separated spots. • Irregular structure in overlap area (translation parallel to laser polarization). - Abstract: The phenomenon of covering large areas with coherent LIPSS produced by multiple, adjacent spots is investigated by varying spot overlap and irradiation dose per spot. In contrast to the typical experimental arrangement, the linear traces of spots were produced by discontinuously advancing the sample between the individual spots. We show that even with almost no overlap the LIPSS patterns appear to be coherently connected.

  4. Rabi-like splitting from large area plasmonic microcavity

    Directory of Open Access Journals (Sweden)

    Fatemeh Hosseini Alast

    2017-08-01

    Full Text Available Rabi-like splitting was observed from a hybrid plasmonic microcavity. The splitting comes from the coupling of cavity mode with the surface plasmon polariton mode; anti-crossing was observed alongside the modal conversional channel on the reflection light measurement. The hybrid device consists of a 10x10 mm2 ruled metal grating integrated onto the Fabry-Perot microcavity. The 10x10 mm2 ruled metal grating fabricated from laser interference and the area is sufficiently large to be used in the practical optical device. The larger area hybrid plasmonic microcavity can be employed in polariton lasers and biosensors.

  5. Facile Fabrication of Large Area Polystyrene Colloidal Crystal Monolayer via Surfactant-free Langmuir-Blodgett Technique

    Institute of Scientific and Technical Information of China (English)

    RUAN Wei-dong; L(U) Zhi-cheng; JI Nan; WANG Chun-xu; ZHAO Bing; ZHANG Jun-hu

    2007-01-01

    A facile and novel method for the production of a large area of well-ordered polystyrene(PS) colloidal crystal monolayer was established using the surfactant-free Langmuir-Blodgett (LB) technique. The hydrophobic property(film-forming ability) of PS spheres was improved by a thermo-rheology treatment before LB assembly, and a large film was obtained. In contrast to the traditional LB technique, no surfactant was needed in this method, which could eliminate the additional contamination of surfactants in the preparation process and provided the products with versatile applications in nanosphere lithography(NSL) for biosensor, surface plasmon resonance, and surface enhanced Raman spectroscopy.

  6. Large-area synthesis of high-quality and uniform monolayer WS2 on reusable Au foils

    Science.gov (United States)

    Gao, Yang; Liu, Zhibo; Sun, Dong-Ming; Huang, Le; Ma, Lai-Peng; Yin, Li-Chang; Ma, Teng; Zhang, Zhiyong; Ma, Xiu-Liang; Peng, Lian-Mao; Cheng, Hui-Ming; Ren, Wencai

    2015-10-01

    Large-area monolayer WS2 is a desirable material for applications in next-generation electronics and optoelectronics. However, the chemical vapour deposition (CVD) with rigid and inert substrates for large-area sample growth suffers from a non-uniform number of layers, small domain size and many defects, and is not compatible with the fabrication process of flexible devices. Here we report the self-limited catalytic surface growth of uniform monolayer WS2 single crystals of millimetre size and large-area films by ambient-pressure CVD on Au. The weak interaction between the WS2 and Au enables the intact transfer of the monolayers to arbitrary substrates using the electrochemical bubbling method without sacrificing Au. The WS2 shows high crystal quality and optical and electrical properties comparable or superior to mechanically exfoliated samples. We also demonstrate the roll-to-roll/bubbling production of large-area flexible films of uniform monolayer, double-layer WS2 and WS2/graphene heterostructures, and batch fabrication of large-area flexible monolayer WS2 film transistor arrays.

  7. Trends in the development of large area photon detectors for Cherenkov light imaging applications

    CERN Document Server

    Nappi, E

    2003-01-01

    Since the successful operations of hi-tech devices at OMEGA, DELPHI and SLD, the technique of Cherenkov light imaging has gone through an impressive and fruitful evolution driven by the conception of novel large area photon detectors. The well-assessed potentialities of thin CsI films, employed as reflective photoconverters in gas counters operated at atmospheric pressure, will be compared with the promising features of hybrid and multianode vacuum photomultipliers. Recently proposed single-photon gaseous detectors based on GEMs will also be reviewed.

  8. Large-area smart glass and integrated photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Lampert, C.M. [Star Science, 8730 Water Road, Cotati, CA 94931-4252 (United States)

    2003-04-01

    Several companies throughout the world are developing dynamic glazing and large-area flat panel displays. University and National Laboratory groups are researching new materials and processes to improve these products. The concept of a switchable glazing for building and vehicle application is very attractive. Conventional glazing only offers fixed transmittance and control of energy passing through it. Given the wide range of illumination conditions and glare, a dynamic glazing with adjustable transmittance offers the best solution. Photovoltaics can be integrated as power sources for smart windows. In this way a switchable window could be a completely stand alone smart system. A new range of large-area flat panel display including light-weight and flexible displays are being developed. These displays can be used for banner advertising, dynamic pricing in stores, electronic paper, and electronic books, to name only a few applications. This study covers selected switching technologies including electrochromism, suspended particles, and encapsulated liquid crystals.

  9. Large area bismuth absorbers for X-ray microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Vaillancourt, J.E. E-mail: vaillancourt@wisp.physics.wisc.edu; Allen, C.A.; Brekosky, R.; Dosaj, A.; Galeazzi, M.; Kelley, R.; Liu, D.; McCammon, D.; Porter, F.S.; Rocks, L.E.; Sanders, W.T.; Stahle, C.K

    2004-03-11

    Two challenges facing the use of large area (2 mmx2 mm) bismuth absorbers for microcalorimetry are uncertainties in the heat capacity of bismuth and the effects of lateral heat conduction and position dependence due to the absorber's large size. We have measured the heat capacity of three Bi samples to be 0.3-0.6 J K{sup -1} m{sup -3} at 100 mK. These absorbers also exhibit response variations as phonons created by an X-ray event at an absorber edge will take longer to propagate to the thermometer attachment point than those at the absorber center. This effect may degrade the detector's energy resolution if the propagation time is not very short compared to the thermometer time constant. We show that the response of the largest absorber varies by {approx}4% across its area.

  10. Characterization of large area APDs for the EXO-200 detector

    CERN Document Server

    Neilson, R; Pocar, A; Kumar, K; Odian, A; Prescott, C Y; Tenev, V; Ackerman, N; Akimov, D; Auger, M; Benitez-Medina, C; Breidenbach, M; Burenkov, A; Conley, R; Cook, S; deVoe, R; Dolinski, M J; Fairbank, W; Farine, J; Fierlinger, P; Flatt, B; Gornea, R; Gratta, G; Green, M; Hall, C; Hall, K; Hallman, D; Hargrove, C; Herrin, S; Hodgson, J; Kaufman, L J; Kovalenko, A; Leonard, D S; Mackay, D; Mong, B; Diez, M Montero; Niner, E; O'Sullivan, K; Piepke, A; Rowson, P C; Sinclair, D; Skarpaas, K; Slutsky, S; Stekhanov, V; Strickland, V; Twelker, K; Vuilleumier, J -L; Wamba, K; Wichoski, U; Wodin, J; Yang, L; Yen, Y -R

    2009-01-01

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  11. Gravure printing of graphene for large-area flexible electronics.

    Science.gov (United States)

    Secor, Ethan B; Lim, Sooman; Zhang, Heng; Frisbie, C Daniel; Francis, Lorraine F; Hersam, Mark C

    2014-07-09

    Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.

  12. Chemical vapor deposition of silicon carbide for large area mirrors

    Science.gov (United States)

    Gentilman, R. L.; Maguire, E. A.

    1982-05-01

    CVD-SiC has been identified as the leading mirror material for high energy synchrotron radiation because of its high K/alpha ratio and its ability to be super-polished to less than or equal to 10 A rms roughness. Technology already exists for depositing SiC over large areas (approximately 70 cm x 20 cm). The CVD process, substrate selection, and mirror design considerations are discussed.

  13. Characterization of Large Area APDs for the EXO-200 Detector

    Energy Technology Data Exchange (ETDEWEB)

    Neilson, R.; LePort, F.; Pocar, A.; /Stanford U., Phys. Dept.; Kumar, K.; /Massachusetts U., Amherst; Odian, A.; Prescott, C.Y.; /SLAC; Tenev, V.; /Stanford U., Phys. Dept.; Ackerman, N.; /SLAC; Akimov, D.; /Moscow, ITEP; Auger, M.; /Bern U., LHEP; Benitez-Medina, C.; /Colorado State U.; Breidenbach, M.; /SLAC; Burenkov, A.; /Moscow, ITEP; Conley, R.; /SLAC; Cook, S.; /Colorado State U.; deVoe, R.; Dolinski, M.J.; /Stanford U., Phys. Dept.; Fairbank, W., Jr.; /Colorado State U.; Farine, J.; /Laurentian U.; Fierlinger, P.; Flatt, B.; /Stanford U., Phys. Dept. /Bern U., LHEP /Stanford U., Phys. Dept. /Maryland U. /Colorado State U. /Laurentian U. /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Alabama U. /SLAC /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Carleton U. /Stanford U., Phys. Dept. /Bern U., LHEP /SLAC /Laurentian U. /SLAC /Maryland U.

    2011-12-02

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  14. Large-mode-area leaky optical fibre fabricated by MCVD

    OpenAIRE

    Dussardier, Bernard; Trzesien, Stanislaw; Ude, Michèle; Rastogi, Vipul; Kumar, Ajeet; Monnom, Gérard

    2008-01-01

    International audience; A large mode area single-mode optical fibre based on leaky mode filtering was prepared by MCVD. The cladding structure discriminates the fundamental mode from the higher order ones. A preliminary version has 25-µm core diameter and 0.11 numerical aperture. A Gaussian-like mode with 22-µm MFD is observed after 3-m propagation, in agreement with modeling.

  15. Uniform large-area thermionic cathode for SCALPEL

    Science.gov (United States)

    Katsap, Victor; Sewell, Peter B.; Waskiewicz, Warren K.; Zhu, Wei

    1999-11-01

    An electron beam lithography tool, which employs the SCALPEL technique, requires an extremely uniform beam to illuminate the scattering Mask, with the cathode operating in the temperature limited mode. It has been previously shown that LaB6 cathodes are not stable in this mode of operation. We have explored the possibility of implementing refined Tantalum-based emitters in the SCALPEL source cathode, and have developed large-area flat cathodes featuring suitably high emission uniformity under temperature limited operation.

  16. High Energy Astrophysics with the Fermi Large Area Telescope

    Science.gov (United States)

    Hays, Elizabeth

    2009-01-01

    This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

  17. Development of large-area CZT detector systems

    Science.gov (United States)

    Kuvvetli, Irfan; Budtz-Joergensen, Carl C.; Westergaard, Niels J.; Jonasson, Per; van Pamelen, Mike A.; Reglero, Victor; Eyles, Christopher J.; Neubert, Torsten

    1999-10-01

    DSRI has initiated a development program of CZT x-ray and gamma ray detectors employing strip readout techniques. A dramatic improvement of the energy response was found operating the detectors as so-called drift detectors. For the electronic readout, modern ASIC chips were investigated. Modular design and the low power electronics will make large area detectors using the drift strip method feasible. The performance of a prototype CZT system will be presented and discussed.

  18. Pilot Production of Large Area Microchannel Plates and Picosecond Photodetectors

    Science.gov (United States)

    Minot, M.; Adams, B.; Abiles, M.; Bond, J.; Craven, C.; Cremer, T.; Foley, M.; Lyashenko, A.; Popecki, M.; Stochaj, M.; Worstell, W.; Elam, J.; Mane, A.; Siegmund, O.; Ertley, C.

    2016-09-01

    Pilot production performance is reported for large area atomic layer deposition (ALD) coated microchannel plates (ALD-GCA-MCPs) and for Large Area Picosecond Photodetectors (LAPPD™) which incorporate them. "Hollowcore" glass capillary array (GCA) substrates are coated with ALD resistive and emissive layers to form the ALDGCA- MCPs, an approach that facilitates independent selection of glass substrates that are mechanically stronger and that have lower levels of radioactive alkali elements compared to conventional MCP lead glass, reducing background noise[1,2,3,4]. ALD-GCA-MCPs have competitive gain ( 104 each or 107 for a chevron pair ), enhanced lifetime and gain stability (7 C cm-2 of charge extraction), reduced background levels (0.028 events cm-2 sec-1) and low gamma-ray detection efficiency. They can be fabricated in large area (20cm X 20 cm) planar and curved formats suitable for use in high radiation environment applications, including astronomy, space instrumentation, and remote night time sensing. The LAPPD™ photodetector incorporates these ALD-GCA-MCPs in an all-glass hermetic package with top and bottom plates and sidewalls made of borosilicate float glass. Signals are generated by a bi-alkali Na2KSb photocathode, amplified with a stacked chevron pair of ALD-GCA-MCPs. Signals are collected on RF strip-line anodes integrated into to the bottom plates which exit the detector via pin-free hermetic seals under the side walls [5]. Tests show that LAPPDTMs have electron gains greater than 107, submillimeter spatial resolution for large (multiphoton) pulses and several mm for single photons, time resolution less than 50 picoseconds for single photons, predicted resolution less than 5 picoseconds for large pulses, high stability versus charge extraction[6], and good uniformity for applications including astrophysics, neutron detection, high energy physics Cherenkov light detection, and quantum-optical photon-correlation experiments.

  19. Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

    2008-02-05

    The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

  20. Characterization of large size YBa2Cu3O7-δ films using magnetic field penetration

    Science.gov (United States)

    Almog, B.; Azoulay, M.; Castro, H.; Deutscher, G.

    2005-11-01

    High critical current density (jc) is one of the most important properties of high Tc superconducting thin films. Determining it is difficult especially in large films (2-3 inch). We propose a non-destructive and easy technique for measuring jc. From measurements of the magnetic moment in the middle of a superconducting film as a function of the external magnetic field, we calculate the macroscopic critical current density.

  1. Large area radiation source for water and wastewater treatment

    Science.gov (United States)

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

    2011-06-01

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

  2. Large areas elemental mapping by ion beam analysis techniques

    Science.gov (United States)

    Silva, T. F.; Rodrigues, C. L.; Curado, J. F.; Allegro, P.; Moro, M. V.; Campos, P. H. O. V.; Santos, S. B.; Kajiya, E. A. M.; Rizzutto, M. A.; Added, N.; Tabacniks, M. H.

    2015-07-01

    The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

  3. A Large Area Detector proposed for the Large Observatory for X-ray Timing (LOFT)

    CERN Document Server

    Zane, S; Kennedy, T; Feroci, M; Herder, J -W Den; Ahangarianabhari, M; Argan, A; Azzarello, P; Baldazzi, G; Barret, D; Bertuccio, G; Bodini, P; Bozzo, E; Cadoux, F; Cais, P; Campana, R; Coker, J; Cros, A; Del Monte, E; De Rosa, A; Di Cosimo, S; Donnarumma, I; Evangelista, Y; Favre, Y; Feldman, C; Fraser, G; Fuschino, F; Grassi, M; Hailey, M R; Hudec, R; Labanti, C; Macera, D; Malcovati, P; Marisaldi, M; Martindale, A; Mineo, T; Muleri, F; Nowak, M; Orlandini, M; Pacciani, L; Perinati, E; Petracek, V; Pohl, M; Rachevski, A; Smith, P; Santangelo, A; Seyler, J -Y; Schmid, C; Soffitta, P; Suchy, S; Tenzer, C; Uttley, P; Vacchi, A; Zampa, G; Zampa, N; Wilms, J; Winter, B

    2012-01-01

    The Large Observatory for X-ray Timing (LOFT) is one of the four candidate ESA M3 missions considered for launch in the 2022 time-frame. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. The LOFT scientific payload is composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a 10 m2-class pointed instrument with 20 times the collecting area of the best past timing missions (such as RXTE) over the 2-30 keV range, which holds the capability to revolutionize studies of X-ray variability down to the millisecond time scales. Its ground-breaking characteristic is a low mass per unit surface, enabling an effective area of ~10 m^2 (@10 keV) at a reasonable weight. The development of such large but light experiment, with low mass and power per unit area, is now made possible by the recent advancements in the field of large-area silicon detectors - able to time tag an X-ray photon with an accuracy <10 {\\mu}s and an...

  4. Large area flexible SERS active substrates using engineered nanostructures

    Science.gov (United States)

    Chung, Aram J.; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as

  5. Large-area photogrammetry based testing of wind turbine blades

    Science.gov (United States)

    Poozesh, Peyman; Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter; Harvey, Eric; Yarala, Rahul

    2017-03-01

    An optically based sensing system that can measure the displacement and strain over essentially the entire area of a utility-scale blade leads to a measurement system that can significantly reduce the time and cost associated with traditional instrumentation. This paper evaluates the performance of conventional three dimensional digital image correlation (3D DIC) and three dimensional point tracking (3DPT) approaches over the surface of wind turbine blades and proposes a multi-camera measurement system using dynamic spatial data stitching. The potential advantages for the proposed approach include: (1) full-field measurement distributed over a very large area, (2) the elimination of time-consuming wiring and expensive sensors, and (3) the need for large-channel data acquisition systems. There are several challenges associated with extending the capability of a standard 3D DIC system to measure entire surface of utility scale blades to extract distributed strain, deflection, and modal parameters. This paper only tries to address some of the difficulties including: (1) assessing the accuracy of the 3D DIC system to measure full-field distributed strain and displacement over the large area, (2) understanding the geometrical constraints associated with a wind turbine testing facility (e.g. lighting, working distance, and speckle pattern size), (3) evaluating the performance of the dynamic stitching method to combine two different fields of view by extracting modal parameters from aligned point clouds, and (4) determining the feasibility of employing an output-only system identification to estimate modal parameters of a utility scale wind turbine blade from optically measured data. Within the current work, the results of an optical measurement (one stereo-vision system) performed on a large area over a 50-m utility-scale blade subjected to quasi-static and cyclic loading are presented. The blade certification and testing is typically performed using International

  6. High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

    2017-06-27

    Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm(2) active area and 18% over a 1 cm(2) active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

  7. Development of practical application technology for photovoltaic power generation systems in fiscal 1997. Development of technologies to manufacture thin film solar cells, development of technologies to manufacture low-cost large-area modules, development of technologies to manufacture next-generation thin film solar cells (development of technologies to manufacture CIS solar cell modules); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu. Usumaku taiyo denchi no seizo gijutsu kaihatsu, tei cost daimenseki module seizo gijutsu kaihatsu, jisedai usumaku taiyo denchi no seizo gijutsu kaihatsu (CIS taiyo denchi module no seizo gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Research and development was made with an objective to achieve conversion efficiency of 13% in a 30 cm times 30 cm size submodule of a CIS-based thin film solar cell, and to develop a manufacturing technology that can achieve 140 yen/Wp. This paper describes the achievements attained during fiscal 1997. In fiscal 1997, based on the achievements reached during the previous year, a submodule with a size of 10 cm times 30 cm was fabricated for an attempt of improving the open voltage and short circuit current density. Simultaneously, the applicability thereof to a module with an area as large as 30 cm times 30 cm was evaluated. As a result of experimental discussions, enhancement in the open voltage was verified by increasing amount of Ga or sulfur, but it was not possible to achieve 600 mV or higher. In the research of component technologies to establish a mass production process, research and development was made on a high-resistance buffer layer film forming technology, a high-quality window layer film forming technology, a high-quality metallic rear electrode film forming technology, and patterning technologies. The outdoor exposure test was continued on laminated mini-modules with a size of 10 cm times 10 cm. (NEDO)

  8. Priority areas for large mammal conservation in Equatorial Guinea.

    Science.gov (United States)

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789) elephants and 11,097 (8,719-13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and Río Campo

  9. Amplifiers dedicated for large area SiC photodiodes

    Science.gov (United States)

    Doroz, P.; Duk, M.; Korwin-Pawlowski, M. L.; Borecki, M.

    2016-09-01

    Large area SiC photodiodes find applications in optoelectronic sensors working at special conditions. These conditions include detection of UV radiation in harsh environment. Moreover, the mentioned sensors have to be selective and resistant to unwanted signals. For this purpose, the modulation of light at source unit and the rejection of constant current and low frequency component of signal at detector unit are used. The popular frequency used for modulation in such sensor is 1kHz. The large area photodiodes are characterized by a large capacitance and low shunt resistance that varies with polarization of the photodiode and can significantly modify the conditions of signal pre-amplification. In this paper two pre-amplifiers topology are analyzed: the transimpedance amplifier and the non-inverting voltage to voltage amplifier with negative feedback. The feedback loops of both pre-amplifiers are equipped with elements used for initial constant current and low frequency signals rejections. Both circuits are analyzed and compared using simulation and experimental approaches.

  10. MILDOS-AREA: An enhanced version of MILDOS for large-area sources

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Y.C.; Wang, J.H.C.; Zielen, A.

    1989-06-01

    The MILDOS-AREA computer code is a modified version of the MILDOS code, which estimates the radiological impacts of airborne emissions from uranium mining and milling facilities or any other large-area source involving emissions of radioisotopes of the uranium-238 series. MILDOS-AREA is designed for execution on personal computers. The modifications incorporated in the MILDOS-AREA code provide enhanced capabilities for calculating doses from large-area sources and update dosimetry calculations. The major revision from the original MILDOS code is the treatment of atmospheric dispersion from area sources: MILDOS-AREA substitutes a finite element integration approach for the virtual-point method (the algorithm used in the original MILDOS code) when specified by the user. Other revisions include the option of using Martin-Tickvart dispersion coefficients in place of Briggs coefficients for a given source, consideration of plume reflection, and updated internal dosimetry calculations based on the most recent recommendations of the International Commission on Radiation Protection and the age-specific dose calculation methodology developed by Oak Ridge National Laboratory. This report also discusses changes in computer code structure incorporated into MILDOS-AREA, summarizes data input requirements, and provides instructions for installing and using the program on personal computers. 15 refs., 9 figs., 26 tabs.

  11. Development of a large area microstructure photomultiplier assembly (LAMPA)

    Science.gov (United States)

    Clifford, E. T. H.; Dick, M.; Facina, M.; Wakeford, D.; Andrews, H. R.; Ing, H.; Best, D.; Baginski, M. J.

    2017-05-01

    Large area (> m2) position-sensitive readout of scintillators is important for passive/active gamma and neutron imaging for counter-terrorism applications. The goal of the LAMPA project is to provide a novel, affordable, large-area photodetector (8" x 8") by replacing the conventional dynodes of photomultiplier tubes (PMTs) with electron multiplier microstructure boards (MSBs) that can be produced using industrial manufacturing techniques. The square, planar format of the LAMPA assemblies enables tiling of multiple units to support large area applications. The LAMPA performance objectives include comparable gain, noise, timing, and energy resolution relative to conventional PMTs, as well as spatial resolution in the few mm range. The current LAMPA prototype is a stack of 8" x 8" MSBs made commercially by chemical etching of a molybdenum substrate and coated with hydrogen-terminated boron-doped diamond for high secondary emission yield (SEY). The layers of MSBs are electrically isolated using ceramic standoffs. Field-shaping grids are located between adjacent boards to achieve good transmission of electrons from one board to the next. The spacing between layers and the design of the microstructure pattern and grids were guided by simulations performed using an electro-optics code. A position sensitive anode board at the back of the stack of MSBs provides 2-D readout. This presentation discusses the trade studies performed in the design of the MSBs, the measurements of SEY from various electro-emissive materials, the electro-optics simulations conducted, the design of the 2-D readout, and the mechanical aspects of the LAMPA design, in order to achieve a gain of > 104 in an 8-stage stack of MSBs, suitable for use with various scintillators when coupled to an appropriate photocathode.

  12. Large scale land use cartography of special areas

    Energy Technology Data Exchange (ETDEWEB)

    Amico, F.D.; Maccarone, D.; Pandiscia, G.V. [NuovaTelespazio S.p.A., Rome (Italy)] [and others

    1996-11-01

    On 06 October 1993 an aerial remote sensing mission has been done on the {open_quote}Mounts of the Sila{close_quotes} area, using a DAEDALUS ATM multispectral scanner, in the framework of the TELAER project, supported by I.A.S.M. (Istituto per l`Assistenza e lo Sviluppo del Mezzogiorno). The study area is inside the National Park of Calabria, well known for its coniferous forests. The collected imagery were used to produce a large scale land use cartography, on the scale of 1 to 5000, extracting information on natural and anthropical vegetation from the multispectral images, with the aid of stereo photos acquired simultaneously. 5 refs., 1 fig., 1 tab.

  13. Large-area Kapton x-ray windows

    Science.gov (United States)

    Antimonov, M.; Khounsary, A.; Weigand, S.; Rix, J.; Keane, D.; Grudzinski, J. J.; Johnson, A.; Zhou, Z.; Jansma, W.

    2015-09-01

    Some X-ray instruments require the utilization of large-area windows to provide vacuum barriers. The necessary attributes of the window material include transparency to X-rays, low scattering, and possession of suitable mechanical properties for reliable long-term performance. Kapton is one such material except that it is a polymer and a large window made from Kapton with a pressure differential of one atmosphere across it can undergo substantial deformation at room temperature. In this paper, we report on the mechanical testing of Kapton samples including creep measurements, and comparison with published data. We use of these data together with analytical / numerical models to predict the changes in the profile of Kapton vacuum windows over time, and show good agreement with experimental measurements.

  14. Laterally periodic resonator for large-area gain lasers.

    Science.gov (United States)

    Feng, Yan; Ueda, Ken-Ichi

    2003-03-24

    Laterally periodic resonators, which can be constructed by use of transversely periodic phase- or amplitude-modulating elements in a cavity, are proposed for stabilization and generation of transversely coherent output from large-area gain. Lasers with periodic resonators have the combined features of conventional cavities and laser arrays. Significant low-order transverse modes and mode discrimination of a sample resonator with intracavity periodic phase elements are investigated numerically by the iteration method. Wave-propagation calculations are carried out by use of a fast Fourier transform, and a modified Prony method is used to evaluate wave functions and losses of transverse modes. Results of numerical calculations are consistent with expectations.

  15. Fermi Large Area Telescope Bright Gamma-ray Source List

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /KIPAC, Menlo Park /SLAC; Ajello, M.; /KIPAC, Menlo Park /SLAC; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U., OKC /Stockholm U.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Band, D.L.; /NASA, Goddard /NASA, Goddard; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Bechtol, K.; /KIPAC, Menlo Park /SLAC; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /KIPAC, Menlo Park /SLAC; Bignami, G.F.; /Pavia U.; Bloom, Elliott D.; /KIPAC, Menlo Park /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /KIPAC, Menlo Park /SLAC; Bregeon, J.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /KIPAC, Menlo Park /SLAC /IASF, Milan /IASF, Milan /DAPNIA, Saclay /ASDC, Frascati /INFN, Perugia /Perugia U. /KIPAC, Menlo Park /SLAC /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /KIPAC, Menlo Park /SLAC /INFN, Perugia /Perugia U. /KIPAC, Menlo Park /SLAC /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /KIPAC, Menlo Park /SLAC /ASDC, Frascati /NASA, Goddard /Maryland U. /Naval Research Lab, Wash., D.C. /INFN, Trieste /Pavia U. /Bari U. /INFN, Bari /KIPAC, Menlo Park /SLAC /UC, Santa Cruz /KIPAC, Menlo Park /SLAC /KIPAC, Menlo Park /SLAC /KIPAC, Menlo Park /SLAC /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /NASA, Goddard; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  16. An insulating grid spacer for large-area MICROMEGAS chambers

    CERN Document Server

    Bernard, D; D'Enterria, D G; Le Guay, M; Martínez, G; Mora, M J; Pichot, P; Roy, D; Schutz, Y; Gandi, A; De Oliveira, R

    2002-01-01

    We present an original design for large area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides an uniform 200 $\\mu$m amplification gap. The uniformity of the amplification gap thickness has been verified under several experimental conditions. The gain performances of the detector are presented and compared to the values obtained with detectors using cylindrical micro spacers. The new design presents several technical and financial advantages.

  17. Large Area Pico-second Photodetectors (LAPPD) in Liquid Argon

    Science.gov (United States)

    Dharmapalan, Ranjan; Lappd Collaboration

    2015-04-01

    The Large Area Pico-second Photodetector (LAPPD) project has recently produced the first working devices with a small form factor and pico-second timing resolution. A number of current and proposed neutrino and dark matter experiments use liquid argon as a detector medium. A flat photodetector with excellent timing resolution will help with background suppression and improve the overall sensitivity of the experiment. We present the research done and some preliminary results to customize the LAPPD devices to work in a cryogenic environment. Argonne National Laboratory (LDRD) and DOE.

  18. Method of manufacturing a large-area segmented photovoltaic module

    Science.gov (United States)

    Lenox, Carl

    2013-11-05

    One embodiment of the invention relates to a segmented photovoltaic (PV) module which is manufactured from laminate segments. The segmented PV module includes rectangular-shaped laminate segments formed from rectangular-shaped PV laminates and further includes non-rectangular-shaped laminate segments formed from rectangular-shaped and approximately-triangular-shaped PV laminates. The laminate segments are mechanically joined and electrically interconnected to form the segmented module. Another embodiment relates to a method of manufacturing a large-area segmented photovoltaic module from laminate segments of various shapes. Other embodiments relate to processes for providing a photovoltaic array for installation at a site. Other embodiments and features are also disclosed.

  19. Large-area settlement pattern recognition from Landsat-8 data

    Science.gov (United States)

    Wieland, Marc; Pittore, Massimiliano

    2016-09-01

    The study presents an image processing and analysis pipeline that combines object-based image analysis with a Support Vector Machine to derive a multi-layered settlement product from Landsat-8 data over large areas. 43 image scenes are processed over large parts of Central Asia (Southern Kazakhstan, Kyrgyzstan, Tajikistan and Eastern Uzbekistan). The main tasks tackled by this work include built-up area identification, settlement type classification and urban structure types pattern recognition. Besides commonly used accuracy assessments of the resulting map products, thorough performance evaluations are carried out under varying conditions to tune algorithm parameters and assess their applicability for the given tasks. As part of this, several research questions are being addressed. In particular the influence of the improved spatial and spectral resolution of Landsat-8 on the SVM performance to identify built-up areas and urban structure types are evaluated. Also the influence of an extended feature space including digital elevation model features is tested for mountainous regions. Moreover, the spatial distribution of classification uncertainties is analyzed and compared to the heterogeneity of the building stock within the computational unit of the segments. The study concludes that the information content of Landsat-8 images is sufficient for the tested classification tasks and even detailed urban structures could be extracted with satisfying accuracy. Freely available ancillary settlement point location data could further improve the built-up area classification. Digital elevation features and pan-sharpening could, however, not significantly improve the classification results. The study highlights the importance of dynamically tuned classifier parameters, and underlines the use of Shannon entropy computed from the soft answers of the SVM as a valid measure of the spatial distribution of classification uncertainties.

  20. Large area x-ray detectors for cargo radiography

    Science.gov (United States)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  1. Large-area high-quality graphene on Ge(001)/Si(001) substrates

    Science.gov (United States)

    Pasternak, I.; Dabrowski, P.; Ciepielewski, P.; Kolkovsky, V.; Klusek, Z.; Baranowski, J. M.; Strupinski, W.

    2016-05-01

    Various experimental data revealing large-area high-quality graphene films grown by the CVD method on Ge(001)/Si(001) substrates are presented. SEM images have shown that the structure of nano-facets is formed on the entire surface of Ge(001), which is covered by a graphene layer over the whole macroscopic sample surface of 1 cm2. The hill-and-valley structures are positioned 90° to each other and run along the direction. The hill height in relation to the valley measured by STM is about 10 nm. Raman measurements have shown that a uniform graphene monolayer covers the nano-facet structures on the Ge(001) surface. Raman spectroscopy has also proved that the grown graphene monolayer is characterized by small strain variations and minimal charge fluctuations. Atomically resolved STM images on the hills of the nanostructures on the Ge(001) surface have confirmed the presence of a graphene monolayer. In addition, the STS/CITS maps show that high-quality graphene has been obtained on such terraces. The subsequent coalescence of graphene domains has led to a relatively well-oriented large-area layer. This is confirmed by LEED measurements, which have indicated that two orientations are preferable in the grown large-area graphene monolayer. The presence of large-area coverage by graphene has been also confirmed by low temperature Hall measurements of a macroscopic sample, showing an n-type concentration of 9.3 × 1012 cm-2 and a mobility of 2500 cm2 V-1 s-1. These important characteristic features of graphene indicate a high homogeneity of the layer grown on the large area Ge(001)/Si(001) substrates.

  2. Four-point probe electrical resistivity scanning system for large area conductivity and activation energy mapping.

    Science.gov (United States)

    Shimanovich, Klimentiy; Bouhadana, Yaniv; Keller, David A; Rühle, Sven; Anderson, Assaf Y; Zaban, Arie

    2014-05-01

    The electrical properties of metal oxides play a crucial role in the development of new photovoltaic (PV) systems. Here we demonstrate a general approach for the determination and analysis of these properties in thin films of new metal oxide based PV materials. A high throughput electrical scanning system, which facilitates temperature dependent measurements at different atmospheres for highly resistive samples, was designed and constructed. The instrument is capable of determining conductivity and activation energy values for relatively large sample areas, of about 72 × 72 mm(2), with the implementation of geometrical correction factors. The efficiency of our scanning system was tested using two different samples of CuO and commercially available Fluorine doped tin oxide coated glass substrates. Our high throughput tool was able to identify the electrical properties of both resistive metal oxide thin film samples with high precision and accuracy. The scanning system enabled us to gain insight into transport mechanisms with novel compositions and to use those insights to make smart choices when choosing materials for our multilayer thin film all oxide photovoltaic cells.

  3. Development of Large Area CsI Photocathodes for the ALICE/HMPID RICH Detector

    CERN Document Server

    Hoedlmoser, H; Schyns, E

    2005-01-01

    The work carried out within the framework of this PhD deals with the measurement of the photoelectric properties of large area thin film Cesium Iodide (CsI) photocathodes (PCs) which are to be used as a photon converter in a proximity focusing RICH detector for High Momentum Particle Identification (HMPID) in the ALICE experiment at the LHC. The objective was to commission a VUV-scanner setup for in-situ measurements of the photoelectric response of the CsI PCs immediately after the thin film coating process and the use of this system to investigate the properties of these photon detectors. Prior to this work and prior to the finalization of the ALICE/HMPID detector design, R&D work investigating the properties of CsI PCs had been performed at CERN and at other laboratories in order to determine possible substrates and optimized thin film coating procedures. These R&D studies were usually carried out with small samples on different substrates and with various procedures with sometimes ambiguous result...

  4. Wind Data Analysis and Wind Flow Simulation Over Large Areas

    Directory of Open Access Journals (Sweden)

    Terziev Angel

    2014-03-01

    Full Text Available Increasing the share of renewable energy sources is one of the core policies of the European Union. This is because of the fact that this energy is essential in reducing the greenhouse gas emissions and securing energy supplies. Currently, the share of wind energy from all renewable energy sources is relatively low. The choice of location for a certain wind farm installation strongly depends on the wind potential. Therefore the accurate assessment of wind potential is extremely important. In the present paper an analysis is made on the impact of significant possible parameters on the determination of wind energy potential for relatively large areas. In the analysis the type of measurements (short- and long-term on-site measurements, the type of instrumentation and the terrain roughness factor are considered. The study on the impact of turbulence on the wind flow distribution over complex terrain is presented, and it is based on the real on-site data collected by the meteorological tall towers installed in the northern part of Bulgaria. By means of CFD based software a wind map is developed for relatively large areas. Different turbulent models in numerical calculations were tested and recommendations for the usage of the specific models in flows modeling over complex terrains are presented. The role of each parameter in wind map development is made. Different approaches for determination of wind energy potential based on the preliminary developed wind map are presented.

  5. Hysteresis in rf-driven large-area josephson junctions

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1986-01-01

    We have studied the effect of an applied rf signal on the radiation emitted from a large-area Josephson junction by means of a model based on the sine-Gordon equation. The rms value of the voltage of the emitted signal has been calculated and a hysteresis loop found. An analysis shows that the hy......We have studied the effect of an applied rf signal on the radiation emitted from a large-area Josephson junction by means of a model based on the sine-Gordon equation. The rms value of the voltage of the emitted signal has been calculated and a hysteresis loop found. An analysis shows...... that the hysteresis is due to the nonlinearity in the system, i.e., the dynamics of the lower branch can be described by a solution to the linearized system while the upper branch is described by a breather mode. These solutions are frequency locked to the driving signal. Various characteristics of the loop...

  6. Thermoelectric properties of CVD grown large area graphene

    Science.gov (United States)

    Sherehiy, Andriy; Jayasinghe, Ruwantha; Stallard, Robert; Sumanasekera, Gamini; Sidorov, Anton; Benjamin, Daniel; Jiang, Zhigang; Yu, Qingkai; Wu, Wei; Bao, Jiming; Liu, Zhihong; Pei, Steven; Chen, Yong

    2010-03-01

    The thermoelectric power (TEP) of CVD (Chemical Vapor Deposition) grown large area graphene transferred onto a Si/SiO2 substrate was measured by simply attaching two miniature thermocouples and a resistive heater. Availability of such large area graphene facilitates straight forward TEP measurement without the use of any microfabrication processes. All investigated graphene samples showed a positive TEP ˜ + 30 μV/K in ambient conditions and saturated at a negative value as low as ˜ -75 μV/K after vacuum-annealing at 500 K in a vacuum of ˜10-7 Torr. The observed p-type behavior under ambient conditions is attributed to the oxygen doping, while the n-type behavior under degassed conditions is due to electron doping from SiO2 surface states. It was observed that the sign of the TEP switched from negative to positive for the degassed graphene when exposed to acceptor gases. Conversely, the TEP of vacuum-annealed graphene exposed to the donor gases became even more negative than the TEP of vacuum-annealed sample.

  7. Large-area proportional counter for in situ transuranic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Miller, K.M.

    1994-12-31

    Improved methods for site characterization are desired for environmental restoration at nuclear facilities. Measurements of transuranics, in particular several isotopes of plutonium, are especially difficult due to the low penetrating nature of the radiations involved, namely, alpha particles and X rays. The effects of attenuation by soil and vegetation generally render direct alpha survey methods useless. For this reason, thin scintillators, such as the FIDLER (field instrument for detection of low-energy radiation) or its more sophisticated successor, the VIOLINIST, that rely on the detection of the L shell X rays (13 to 21 keV) are used for survey work. Semiconductor detectors (germanium and silicon), used singly or in arrays, can be effective, especially for situations where {sup 241}Am (60 keV) is present in the isotropic mix. In principle, in situ spectrometric techniques that have been successfully applied at higher photon energies for the measurement of gamma-emitting radionuclides in the environment can be extended to the X-ray region as well. For situations where {sup 241}Am is not present or its ratio to plutonium is unknown, an alternative detector that we have explored for in situ X-ray spectrometry is a large-area proportional counter (LAPC). These instruments were developed for X-ray astronomical measurements in space and offer the combination of large window area and medium energy resolution. Smaller versions have also been used for lung counting.

  8. Large area nanoimprint by substrate conformal imprint lithography (SCIL)

    Science.gov (United States)

    Verschuuren, Marc A.; Megens, Mischa; Ni, Yongfeng; van Sprang, Hans; Polman, Albert

    2017-06-01

    Releasing the potential of advanced material properties by controlled structuring materials on sub-100-nm length scales for applications such as integrated circuits, nano-photonics, (bio-)sensors, lasers, optical security, etc. requires new technology to fabricate nano-patterns on large areas (from cm2 to 200 mm up to display sizes) in a cost-effective manner. Conventional high-end optical lithography such as stepper/scanners is highly capital intensive and not flexible towards substrate types. Nanoimprint has had the potential for over 20 years to bring a cost-effective, flexible method for large area nano-patterning. Over the last 3-4 years, nanoimprint has made great progress towards volume production. The main accelerator has been the switch from rigid- to wafer-scale soft stamps and tool improvements for step and repeat patterning. In this paper, we discuss substrate conformal imprint lithography (SCIL), which combines nanometer resolution, low patterns distortion, and overlay alignment, traditionally reserved for rigid stamps, with the flexibility and robustness of soft stamps. This was made possible by a combination of a new soft stamp material, an inorganic resist, combined with an innovative imprint method. Finally, a volume production solution will be presented, which can pattern up to 60 wafers per hour.

  9. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    Science.gov (United States)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class; pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  10. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector.

    Science.gov (United States)

    Baker, Jessy L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-06-01

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological and crystallographic information is needed to predict and optimize the film's electrical, optical, and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector in two sample geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

  11. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Jessica L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-02-19

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological information is needed to predict and optimize the film's electronic, optical and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector and synchrotron radiation in two simple geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly-packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

  12. Self-assembly of large-scale crack-free gold nanoparticle films using a ‘drain-to-deposit’ strategy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guang; Hallinan, Daniel T.

    2016-04-26

    Gold nanoparticles are widely studied due to the ease of controlled synthesis, facile surface modification, and interesting physical properties. However, a technique for depositing large-area, crack-free monolayers on solid substrates is lacking. Herein is presented a method for accomplishing this. Spherical gold nanoparticles were synthesized as an aqueous dispersion. Assembly into monolayers and ligand exchange occurred simultaneously at an organic/aqueous interface. Then the monolayer film was deposited onto arbitrary solid substrates by slowly pumping out the lower, aqueous phase. This allowed the monolayer film (and liquid–liquid interface) to descend without significant disturbance, eventually reaching substrates contained in the aqueous phase. The resulting macroscopic quality of the films was found to be superior to films transferred by Langmuir techniques. The surface plasmon resonance and Raman enhancement of the films were evaluated and found to be uniform across the surface of each film.

  13. Self-assembly of large-scale crack-free gold nanoparticle films using a ‘drain-to-deposit’ strategy

    Science.gov (United States)

    Yang, Guang; Hallinan, Daniel T., Jr.

    2016-06-01

    Gold nanoparticles are widely studied due to the ease of controlled synthesis, facile surface modification, and interesting physical properties. However, a technique for depositing large-area, crack-free monolayers on solid substrates is lacking. Herein is presented a method for accomplishing this. Spherical gold nanoparticles were synthesized as an aqueous dispersion. Assembly into monolayers and ligand exchange occurred simultaneously at an organic/aqueous interface. Then the monolayer film was deposited onto arbitrary solid substrates by slowly pumping out the lower, aqueous phase. This allowed the monolayer film (and liquid-liquid interface) to descend without significant disturbance, eventually reaching substrates contained in the aqueous phase. The resulting macroscopic quality of the films was found to be superior to films transferred by Langmuir techniques. The surface plasmon resonance and Raman enhancement of the films were evaluated and found to be uniform across the surface of each film.

  14. Geometric correction methods for Timepix based large area detectors

    Science.gov (United States)

    Zemlicka, J.; Dudak, J.; Karch, J.; Krejci, F.

    2017-01-01

    X-ray micro radiography with the hybrid pixel detectors provides versatile tool for the object inspection in various fields of science. It has proven itself especially suitable for the samples with low intrinsic attenuation contrast (e.g. soft tissue in biology, plastics in material sciences, thin paint layers in cultural heritage, etc.). The limited size of single Medipix type detector (1.96 cm2) was recently overcome by the construction of large area detectors WidePIX assembled of Timepix chips equipped with edgeless silicon sensors. The largest already built device consists of 100 chips and provides fully sensitive area of 14.3 × 14.3 cm2 without any physical gaps between sensors. The pixel resolution of this device is 2560 × 2560 pixels (6.5 Mpix). The unique modular detector layout requires special processing of acquired data to avoid occurring image distortions. It is necessary to use several geometric compensations after standard corrections methods typical for this type of pixel detectors (i.e. flat-field, beam hardening correction). The proposed geometric compensations cover both concept features and particular detector assembly misalignment of individual chip rows of large area detectors based on Timepix assemblies. The former deals with larger border pixels in individual edgeless sensors and their behaviour while the latter grapple with shifts, tilts and steps between detector rows. The real position of all pixels is defined in Cartesian coordinate system and together with non-binary reliability mask it is used for the final image interpolation. The results of geometric corrections for test wire phantoms and paleo botanic material are presented in this article.

  15. LEAP - A Large Area GRB Polarimeter for the ISS

    Science.gov (United States)

    McConnell, Mark L.; Baring, Matthew G.; Bloser, Peter F.; Briggs, Michael Stephen; Connaughton, Valerie; Dwyer, Joseph; Gaskin, Jessica; Grove, J. Eric; Gunji, Shuichi; Hartmann, Dieter; Hayashida, Kiyoshi; Hill, Joanne E.; Kippen, R. Marc; Kishimoto, Shunji; Kishimoto, Yuji; Krizmanic, John F.; Lundman, Christoffer; Mattingly, David; McBreen, Sheila; Meegan, Charles A.; Mihara, Tatehiro; Nakamori, Takeshi; Pearce, Mark; Phlips, Bernard; Preece, Robert D.; Produit, Nicolas; Ryan, James M.; Ryde, Felix; Sakamoto, Takanori; Strickman, Mark Samuel; Sturner, Steven J.; Takahashi, Hiromitsu; Toma, Kenji; Vestrand, W. Thomas; Wilson-Hodge, Colleen A.; yatsu, Yoichi; Yonetoku, Daisuke; Zhang, Bing

    2017-08-01

    The LargE Area burst Polarimeter (LEAP) is a mission concept for a wide FOV Compton scatter polarimeter instrument that would be mounted as an external payload on the International Space Station (ISS) in 2022. It has recently been proposed as an astrophysics Mission of Opportunity (MoO), with the primary objective of measuring polarization of the prompt emission of Gamma Ray Bursts (GRBs). It will achieve its science objectives with a simple mission design that features a single instrument based entirely on well-established, flight-proven scintillator-photomultiplier tube (PMT) technologies. LEAP will provide GRB polarization measurements from 30-500 keV and GRB spectroscopy from 5 keV up to 5 MeV, and will self-sufficiently provide the source localization that is required for analysis of the polarization data. The instrument consists of 9 independent polarimeter modules and associated electronics. Each module is a 12 x 12 array of independent plastic and CsI(Tl) scintillator elements, each with individual PMT readout, to identify and measure Compton scatter events. It will provide coverage of GRB spectra over a range that includes most values of Ep. With a total geometric scintillator area of 5000 cm2, LEAP will provide a total effective area for polarization (double scatter) events of ~500 cm2. LEAP will trigger on >200 GRBs within its FOV during a two-year mission. At least 120 GRBs will have sufficient counts to enable localization with an error of 50%, as suggested by published results, LEAP will provide definitive polarization measurements on ~100 GRBs. These data will allow LEAP to differentiate between the intrinsic and geometric classes of GRB models and further distinguish between two geometric models at the 95% confidence level. Detailed time-resolved and/or energy-resolved studies will be conducted for the brightest GRBs.

  16. Priority areas for large mammal conservation in Equatorial Guinea.

    Directory of Open Access Journals (Sweden)

    Mizuki Murai

    Full Text Available Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1 the relative importance of local vs. commercial hunting; 2 wildlife density of protected vs. non-protected areas; and 3 the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789 elephants and 11,097 (8,719-13,592 chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal

  17. Large-area super-resolution optical imaging by using core-shell microfibers

    Science.gov (United States)

    Liu, Cheng-Yang; Lo, Wei-Chieh

    2017-09-01

    We first numerically and experimentally report large-area super-resolution optical imaging achieved by using core-shell microfibers. The particular spatial electromagnetic waves for different core-shell microfibers are studied by using finite-difference time-domain and ray tracing calculations. The focusing properties of photonic nanojets are evaluated in terms of intensity profile and full width at half-maximum along propagation and transversal directions. In experiment, the general optical fiber is chemically etched down to 6 μm diameter and coated with different metallic thin films by using glancing angle deposition. The direct imaging of photonic nanojets for different core-shell microfibers is performed with a scanning optical microscope system. We show that the intensity distribution of a photonic nanojet is highly related to the metallic shell due to the surface plasmon polaritons. Furthermore, large-area super-resolution optical imaging is performed by using different core-shell microfibers placed over the nano-scale grating with 150 nm line width. The core-shell microfiber-assisted imaging is achieved with super-resolution and hundreds of times the field-of-view in contrast to microspheres. The possible applications of these core-shell optical microfibers include real-time large-area micro-fluidics and nano-structure inspections.

  18. Detection of Steel Fatigue Cracks with Strain Sensing Sheets Based on Large Area Electronics

    Directory of Open Access Journals (Sweden)

    Yao Yao

    2015-04-01

    Full Text Available Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs.

  19. Detection of steel fatigue cracks with strain sensing sheets based on large area electronics.

    Science.gov (United States)

    Yao, Yao; Glisic, Branko

    2015-04-07

    Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm) were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs.

  20. Evaluation of bacterial nanocellulose-based uniform wound dressing for large area skin transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Lina [Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou, Ping [Institute of Organ Transplant of Tongji Hospital, Huazhong University of Science and Technology, Wuhan (China); Zhang, Shengmin [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan (China); Yang, Guang, E-mail: yang_sunny@yahoo.com [Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-07-01

    Bacterial nanocellulose (BNC) was biosynthesized by Gluconacetobacter xylinus. The surface area, physicochemical structure and morphology of the materials were characterized. Here provides a method for an efficient production of uniform BNC, which is beneficial for the fast characterization and evaluation of BNC. In vitro cytotoxicity of the materials was evaluated by the proliferation, the adhesion, the viability and the morphology of NIH/3T3 cells. Low cytotoxicity of the BNC was observed, and micrographs demonstrate a good proliferation and adhesion of NIH/3T3 cells on BNC. Large area full-thickness skin defects were made on the back of C57BL/6 mice in animal surgery. The wounds were transplanted with BNC films and the results compared to those in a control group. The rehabilitation of the wound surfaces and the pathological sections of mice were investigated and are discussed. Histological examinations demonstrated faster and better healing effect and lower inflammatory response in the BNC group than those in the control group. Preliminary results on wound dressings from BNC show a curative effect promoting the healing of epithelial tissue. BNC is a promising natural polymer with medical applications in wound dressings. - Highlights: • BNC is expected to be a promising material in wound healing and skin transplantation. • We studied surface area, physicochemical structures and morphology of uniform BNC. • Cyto-evaluation results of BNC-based wound dressing show a good biocompatibility. • Large area skin transplantation experiments suggest a good performance of healing.

  1. Complex protein nanopatterns over large areas via colloidal lithography

    DEFF Research Database (Denmark)

    Kristensen, Stine H; Pedersen, Gitte Albinus; Ogaki, Ryosuke;

    2013-01-01

    are used to generate complex protein nanopatterns over large areas. Simple circular patches or more complex ring structures are produced in addition to hierarchical patterns of smaller patches. The gold regions are modified through alkanethiol chemistry, which enables the preparation of extracellular......The patterning of biomolecules at the nanoscale provides a powerful method to investigate cellular adhesion processes. A novel method for patterning is presented that is based on colloidal monolayer templating combined with multiple and angled deposition steps. Patterns of gold and SiO2 layers...... for using sets of systematically varied samples with simpler or more complex patterns for studies of cellular adhesive behavior and reveal that the local distribution of proteins within a simple patch critically influences cell adhesion....

  2. Large-area, wide-angle, spectrally selective plasmonic absorber

    CERN Document Server

    Wu, Chihhui; John, Jeremy; Milder, Andrew; Zollars, Byron; Savoy, Steve; Shvets, Gennady

    2011-01-01

    A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive low-cost technology for making large-area samples. The matching of the metamaterial's impedance to that of vacuum is responsible for the observed spectrally selective "perfect" absorption of infrared light. The impedance is theoretically calculated in the single-resonance approximation, and the responsible resonance is identified as a short-range surface plasmon. The spectral position of the absorption peak (which is as high as 95%) is experimentally shown to be controlled by the metamaterial's dimensions. The persistence of "perfect" absorption with variable metamaterial parameters is theoretically explained. The wide-angle nature of the absorber can be utilized for sub-diffraction-scale infrared pixels exhibiting spectrally selective absorption/emissivity.

  3. Large Area Printing of 3D Photonic Crystals

    Science.gov (United States)

    Watkins, James J.; Beaulieu, Michael R.; Hendricks, Nicholas R.; Kothari, Rohit

    2014-03-01

    We have developed a readily scalable print, lift, and stack approach for producing large area, 3D photonic crystal (PC) structures. UV-assisted nanoimprint lithography (UV-NIL) was used to pattern grating structures comprised of highly filled nanoparticle polymer composite resists with tune-able refractive indices (RI). The gratings were robust and upon release from a support substrate were oriented and stacked to yield 3D PCs. The RI of the composite resists was tuned between 1.58 and 1.92 at 800 nm while maintaining excellent optical transparency. The grating structure dimensions, line width, depth, and pitch, were easily varied by simply changing the imprint mold. For example, a 6 layer log-pile stack was prepared using a composite resist a RI of 1.72 yielding 72 % reflection at 900 nm. The process is scalable for roll-to-roll (R2R) production. Center for Hierarchical Manufacturing - an NSF Nanoscale Science and Engineering Center.

  4. Background simulations for the Large Area Detector onboard LOFT

    DEFF Research Database (Denmark)

    Campana, Riccardo; Feroci, Marco; Ettore, Del Monte

    2013-01-01

    is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design...... solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2aEuro'30 keV, achieving about 5 mCrab in the most important 2-10 keV energy band. Moreover, simulations show...... an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than...

  5. Coating and Patterning Functional Materials for Large Area Electrofluidic Arrays

    Directory of Open Access Journals (Sweden)

    Hao Wu

    2016-08-01

    Full Text Available Industrialization of electrofluidic devices requires both high performance coating laminates and efficient material utilization on large area substrates. Here we show that screen printing can be effectively used to provide homogeneous pin-hole free patterned amorphous fluoropolymer dielectric layers to provide both the insulating and fluidic reversibility required for devices. Subsequently, we over-coat photoresist using slit coating on this normally extremely hydrophobic layer. In this way, we are able to pattern the photoresist by conventional lithography to provide the chemical contrast required for liquids dosing by self-assembly and highly-reversible electrofluidic switching. Materials, interfacial chemistry, and processing all contribute to the provision of the required engineered substrate properties. Coating homogeneity as characterized by metrology and device performance data are used to validate the methodology, which is well-suited for transfer to high volume production in existing LCD cell-making facilities.

  6. Non-linear behaviour of large-area avalanche photodiodes

    CERN Document Server

    Fernandes, L M P; Monteiro, C M B; Santos, J M; Morgado, R E

    2002-01-01

    The characterisation of photodiodes used as photosensors requires a determination of the number of electron-hole pairs produced by scintillation light. One method involves comparing signals produced by X-ray absorptions occurring directly in the avalanche photodiode with the light signals. When the light is derived from light-emitting diodes in the 400-600 nm range, significant non-linear behaviour is reported. In the present work, we extend the study of the linear behaviour to large-area avalanche photodiodes, of Advanced Photonix, used as photosensors of the vacuum ultraviolet (VUV) scintillation light produced by argon (128 nm) and xenon (173 nm). We observed greater non-linearities in the avalanche photodiodes for the VUV scintillation light than reported previously for visible light, but considerably less than the non-linearities observed in other commercially available avalanche photodiodes.

  7. Searches for Axionlike Particles with the Fermi Large Area Telescope

    Science.gov (United States)

    Albert, Andrea; Meyer, Manuel; Sanchez-Conde, Miguel; Wood, Matthew; LAT Collaboration

    2017-01-01

    Axionlike particles (ALPs) are dark-matter candidates that occur in a variety of extensions of the Standard Model. These particles could leave signatures in gamma rays, due to the coupling of ALPs to photons in external electromagnetic fields. To date, observations with Fermi Large Area Telescope (LAT) provide the strongest constraints on the photon-ALP coupling for ALP masses between 0.5 and 20 neV. Here, we summarize these constraints and present the sensitivity to detect an ALP induced gamma-ray burst from a Galactic core-collapse supernova. ALPs would be produced in the stellar medium via the Primakoff effect and convert into gamma rays in the Galactic magnetic field. Fermi LAT observations would be able to probe couplings where ALPs could constitute the entirety of dark matter. Below 1 neV, the Fermi-LAT sensitivity would surpass that of future laboratory experiments by one order of magnitude.

  8. Large eddy simulation of urban features for Copenhagen metropolitan area

    Directory of Open Access Journals (Sweden)

    A. Mahura

    2005-11-01

    Full Text Available The large eddy simulations employing the SUBMESO model with the urban soil layer model SM2-U were performed for the model domain covering the Danish Island of Sealand and including the Copenhagen metropolitan area. Monthly and diurnal cycle variability were studied for the net radiation, sensible and storage heat fluxes, surface's temperatures, and others. These were evaluated for selected urban vs. non urban related types of covers/surfaces and urban districts such as city center, high buildings, industrial, and residential. Results showed strong effects of urban features on temporal and spatial variability. They are useful and applicable for verification of numerical weather prediction models and development of urban canopy parameterizations.

  9. Large area MEMS based ultrasound device for cancer detection

    Energy Technology Data Exchange (ETDEWEB)

    Wodnicki, Robert, E-mail: wodnicki@research.ge.com [GE Global Research, 1 Research Circle, Niskayuna, NY 12309 (United States); Thomenius, Kai [GE Global Research, 1 Research Circle, Niskayuna, NY 12309 (United States); Ming Hooi, Fong; Sinha, Sumedha P.; Carson, Paul L. [Radiology and Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Lin Dersong; Zhuang Xuefeng; Khuri-Yakub, Pierre [Department of Electrical Engineering, Stanford University, Stanford, CA 94309 (United States); Woychik, Charles [GE Global Research, 1 Research Circle, Niskayuna, NY 12309 (United States)

    2011-08-21

    We present image results obtained using a prototype ultrasound array that demonstrates the fundamental architecture for a large area MEMS based ultrasound device for detection of breast cancer. The prototype array consists of a tiling of capacitive Micromachined Ultrasound Transducers (cMUTs) that have been flip-chip attached to a rigid organic substrate. The pitch on the cMUT elements is 185 {mu}m and the operating frequency is nominally 9 MHz. The spatial resolution of the new probe is comparable to those of production PZT probes; however the sensitivity is reduced by conditions that should be correctable. Simulated opposed-view image registration and Speed of Sound volume reconstruction results for ultrasound in the mammographic geometry are also presented.

  10. A new approach for defect inspection on large area masks

    Science.gov (United States)

    Scheuring, Gerd; Döbereiner, Stefan; Hillmann, Frank; Falk, Günther; Brück, Hans-Jürgen

    2007-02-01

    Besides the mask market for IC manufacturing, which mainly uses 6 inch sized masks, the market for the so called large area masks is growing very rapidly. Typical applications of these masks are mainly wafer bumping for current packaging processes, color filters on TFTs, and Flip Chip manufacturing. To expose e.g. bumps and similar features on 200 mm wafers under proximity exposure conditions 9 inch masks are used, while in 300 mm wafer bumping processes (Fig. 1) 14 inch masks are handled. Flip Chip manufacturing needs masks up to 28 by 32 inch. This current maximum mask dimension is expected to hold for the next 5 years in industrial production. On the other hand shrinking feature sizes, just as in case of the IC masks, demand enhanced sensitivity of the inspection tools. A defect inspection tool for those masks is valuable for both the mask maker, who has to deliver a defect free mask to his customer, and for the mask user to supervise the mask behavior conditions during its lifetime. This is necessary because large area masks are mainly used for proximity exposures. During this process itself the mask is vulnerable by contacting the resist on top of the wafers. Therefore a regular inspection of the mask after 25, 50, or 100 exposures has to be done during its whole lifetime. Thus critical resist contamination and other defects, which lead to yield losses, can be recognized early. In the future shrinking feature dimensions will require even more sensitive and reliable defect inspection methods than they do presently. Besides the sole inspection capability the tools should also provide highly precise measurement capabilities and extended review options.

  11. Large Area Nondestructive Evaluation of a Fatigue Loaded Composite Structure

    Science.gov (United States)

    Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Madaras, Eric I.

    2016-01-01

    Large area nondestructive evaluation (NDE) inspections are required for fatigue testing of composite structures to track damage initiation and growth. Of particular interest is the progression of damage leading to ultimate failure to validate damage progression models. In this work, passive thermography and acoustic emission NDE were used to track damage growth up to failure of a composite three-stringer panel. Fourteen acoustic emission sensors were placed on the composite panel. The signals from the array were acquired simultaneously and allowed for acoustic emission location. In addition, real time thermal data of the composite structure were acquired during loading. Details are presented on the mapping of the acoustic emission locations directly onto the thermal imagery to confirm areas of damage growth leading to ultimate failure. This required synchronizing the acoustic emission and thermal data with the applied loading. In addition, processing of the thermal imagery which included contrast enhancement, removal of optical barrel distortion and correction of angular rotation before mapping the acoustic event locations are discussed.

  12. The Gamma-ray Large Area Space Telescope (GLAST)

    Science.gov (United States)

    Ritz, Steve

    2008-01-01

    The Gamma-ray Large Area Space Telescope, GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. The very large field of view will make it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its upcoming launch, GLAST will open a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations and Lorentz invariance violation. In addition to the science opportunities, this talk includes a description of the instruments, the opportunities for guest investigators, and the mission status.

  13. Fermi Large Area Telescope as a Galactic Supernovae Axionscope

    Science.gov (United States)

    Meyer, M.; Giannotti, M.; Mirizzi, A.; Conrad, J.; Sánchez-Conde, M. A.

    2017-01-01

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to ga γ≃2 ×10-13 GeV-1 for an ALP mass ma≲10-9 eV . These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to γ rays, stellar cooling anomalies, and cold dark matter. If no γ -ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.

  14. The Fermi Large Area Telescope as a Galactic Supernovae Axionscope

    CERN Document Server

    Meyer, Manuel; Mirizzi, Alessandro; Conrad, Jan; Sanchez-Conde, Miguel

    2016-01-01

    In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into $\\gamma$ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to $g_{a\\gamma} \\simeq 2 \\times 10^{-13}\\,$GeV$^{-1}$ for an ALP mass $m_a \\lesssim 10^{-9}\\,$eV. These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to $\\gamma$ rays, stellar cooling anomalies, and cold dark matter. If no $\\gamma$-ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN1987A by more than one order of magnitude.

  15. Large scale track analysis for wide area motion imagery surveillance

    Science.gov (United States)

    van Leeuwen, C. J.; van Huis, J. R.; Baan, J.

    2016-10-01

    Wide Area Motion Imagery (WAMI) enables image based surveillance of areas that can cover multiple square kilometers. Interpreting and analyzing information from such sources, becomes increasingly time consuming as more data is added from newly developed methods for information extraction. Captured from a moving Unmanned Aerial Vehicle (UAV), the high-resolution images allow detection and tracking of moving vehicles, but this is a highly challenging task. By using a chain of computer vision detectors and machine learning techniques, we are capable of producing high quality track information of more than 40 thousand vehicles per five minutes. When faced with such a vast number of vehicular tracks, it is useful for analysts to be able to quickly query information based on region of interest, color, maneuvers or other high-level types of information, to gain insight and find relevant activities in the flood of information. In this paper we propose a set of tools, combined in a graphical user interface, which allows data analysts to survey vehicles in a large observed area. In order to retrieve (parts of) images from the high-resolution data, we developed a multi-scale tile-based video file format that allows to quickly obtain only a part, or a sub-sampling of the original high resolution image. By storing tiles of a still image according to a predefined order, we can quickly retrieve a particular region of the image at any relevant scale, by skipping to the correct frames and reconstructing the image. Location based queries allow a user to select tracks around a particular region of interest such as landmark, building or street. By using an integrated search engine, users can quickly select tracks that are in the vicinity of locations of interest. Another time-reducing method when searching for a particular vehicle, is to filter on color or color intensity. Automatic maneuver detection adds information to the tracks that can be used to find vehicles based on their

  16. Methods for Finding Legacy Wells in Large Areas

    Energy Technology Data Exchange (ETDEWEB)

    Hammack, Richard W. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Veloski, Garret A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Hodges, D. Greg [Fugro Airborne Surveys, Mississauga, ON (Canada); White, Jr., Curt M. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2016-06-16

    United States. When abandoned, many wells were not adequately sealed and now provide a potential conduit for the vertical movement of liquids and gases. Today, groundwater aquifers can be contaminated by surface pollutants flowing down wells or by deep, saline water diffusing upwards. Likewise, natural gas, carbon dioxide (CO2), or radon can travel upwards via these wells to endanger structures or human health on the surface. Recently, the need to find and plug wells has become critical with the advent of carbon dioxide injection into geologic formations for enhanced oil recovery (EOR) or carbon storage. The potential for natural gas or brine leakage through existing wells has also been raised as a concern in regions where shale resources are hydraulically fractured for hydrocarbon recovery. In this study, the National Energy Technology Laboratory (NETL) updated existing, effective well finding techniques to be able to survey large areas quickly using helicopter or ground-vehicle-mounted magnetometers, combined with mobile methane detection. For this study, magnetic data were collected using airborne and ground vehicles equipped with two boom-mounted magnetometers, or on foot using a hand-held magnetometer with a single sensor. Data processing techniques were employed to accentuate well-casing-type magnetic signatures. To locate wells with no magnetic signature (wells where the steel well casing had been removed), the team monitored for anomalous concentrations of methane, which could indicate migration of volatile compounds from deeper sedimentary strata along a well or fracture pathway. Methane measurements were obtained using the ALPIS DIfferential Absorption Lidar (DIAL) sensor for helicopter surveys and the Apogee leak detection system (LDS) for ground surveys. These methods were evaluated at a 100-year-old oilfield in Wyoming, where a helicopter magnetic survey accurately located 93% of visible wells. In addition, 20% of the wells found by the survey were

  17. Methods for Finding Legacy Wells in Large Areas

    Energy Technology Data Exchange (ETDEWEB)

    Hammack, Richard [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Veloski, Garret [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Hodges, D. Greg [Fugro Airborne Surveys, Mississauga, ON (Canada); White, Jr., Charles E. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2016-06-16

    More than 10 million wells have been drilled during 150 years of oil and gas production in the United States. When abandoned, many wells were not adequately sealed and now provide a potential conduit for the vertical movement of liquids and gases. Today, groundwater aquifers can be contaminated by surface pollutants flowing down wells or by deep, saline water diffusing upwards. Likewise, natural gas, carbon dioxide (CO2), or radon can travel upwards via these wells to endanger structures or human health on the surface. Recently, the need to find and plug wells has become critical with the advent of carbon dioxide injection into geologic formations for enhanced oil recovery (EOR) or carbon storage. The potential for natural gas or brine leakage through existing wells has also been raised as a concern in regions where shale resources are hydraulically fractured for hydrocarbon recovery. In this study, the National Energy Technology Laboratory (NETL) updated existing, effective well finding techniques to be able to survey large areas quickly using helicopter or ground-vehicle-mounted magnetometers, combined with mobile methane detection. For this study, magnetic data were collected using airborne and ground vehicles equipped with two boom-mounted magnetometers, or on foot using a hand-held magnetometer with a single sensor. Data processing techniques were employed to accentuate well-casing-type magnetic signatures. To locate wells with no magnetic signature (wells where the steel well casing had been removed), the team monitored for anomalous concentrations of methane, which could indicate migration of volatile compounds from deeper sedimentary strata along a well or fracture pathway. Methane measurements were obtained using the ALPIS DIfferential Absorption Lidar (DIAL) sensor for helicopter surveys and the Apogee leak detection system (LDS) for ground surveys. These methods were evaluated at a 100-year-old oilfield in Wyoming, where a helicopter magnetic

  18. Large-area landslide susceptibility with optimized slope-units

    Science.gov (United States)

    Alvioli, Massimiliano; Marchesini, Ivan; Reichenbach, Paola; Rossi, Mauro; Ardizzone, Francesca; Fiorucci, Federica; Guzzetti, Fausto

    2017-04-01

    A Slope-Unit (SU) is a type of morphological terrain unit bounded by drainage and divide lines that maximize the within-unit homogeneity and the between-unit heterogeneity across distinct physical and geographical boundaries [1]. Compared to other terrain subdivisions, SU are morphological terrain unit well related to the natural (i.e., geological, geomorphological, hydrological) processes that shape and characterize natural slopes. This makes SU easily recognizable in the field or in topographic base maps, and well suited for environmental and geomorphological analysis, in particular for landslide susceptibility (LS) modelling. An optimal subdivision of an area into a set of SU depends on multiple factors: size and complexity of the study area, quality and resolution of the available terrain elevation data, purpose of the terrain subdivision, scale and resolution of the phenomena for which SU are delineated. We use the recently developed r.slopeunits software [2,3] for the automatic, parametric delineation of SU within the open source GRASS GIS based on terrain elevation data and a small number of user-defined parameters. The software provides subdivisions consisting of SU with different shapes and sizes, as a function of the input parameters. In this work, we describe a procedure for the optimal selection of the user parameters through the production of a large number of realizations of the LS model. We tested the software and the optimization procedure in a 2,000 km2 area in Umbria, Central Italy. For LS zonation we adopt a logistic regression model implemented in an well-known software [4,5], using about 50 independent variables. To select the optimal SU partition for LS zonation, we want to define a metric which is able to quantify simultaneously: (i) slope-unit internal homogeneity (ii) slope-unit external heterogeneity (iii) landslide susceptibility model performance. To this end, we define a comprehensive objective function S, as the product of three

  19. Ti-Zr-V non-evaporable getter films from development to large scale production for the Large Hadron Collider

    CERN Document Server

    Chiggiato, P

    2005-01-01

    Non-evaporable getter (NEG) alloys after dissolution of their native oxide layer into the bulk are able to pump most of the gases present in ultra-high vacuum systems. The dissolution process, commonly called activation, is obtained by heating in vacuum. NEG materials can be sputter-deposited as a thin film on the inner wall of a vacuum chamber, transforming it from a source of gas into an effective pump. The most significant advance in the development of NEG films was the discovery of a very low activation temperature (180°C for 24 h heating) in a large range of compositions of the Ti-Zr-V system. This favourable property was correlated with nanometric grain size of the film (about 3 to 5 nm). In addition to pumping, NEG films lead to reduced induced gas desorption and secondary electron yields. As a consequence, Ti-Zr-V films provide the optimum solution to most of the problems encountered in vacuum systems of modern particle accelerators for high energy physics and for synchrotron radiation facilities. ...

  20. Controlled buckling of thin film on elastomeric substrate in large deformation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Electronic systems with large stretchability have many applications.A precisely controlled buckling strategy to increase the stretchability has been demonstrated by combining lithographically patterned surface bonding chemistry and a buckling process.The buckled geometry was assumed to have a sinusoidal form,which may result in errors to determine the strains in the film.A theoretical model is presented in this letter to study the mechanics of this type of thin film/substrate system by discarding the ass...

  1. Quiet Areas: Outer experiences and inner sensations – a qualitative approach using film and drones

    DEFF Research Database (Denmark)

    Petersen, Rikke Munck

    2016-01-01

    This paper argues that drone filming can substantiate our understanding of multisensorial experiences of quiet areas and urban landscapes. Contrary to the distanced gaze often associated with the drone, this paper discusses drone filming as an intimate performativity apparatus that can affect...... perception as a result of its interrelationships between motion, gaze, and sound. This paper uses four films, one of which is a drone flyover, to launch a discussion concerning a smooth and alluring gaze, a sliding gaze that penetrates landscapes, and site appearance. Films hold the capacity to project both...... and transcendence can facilitate a deeper understanding of intimate sensations, substantiating their role in the future design and planning of urban landscapes. Hence, it addresses the ethics of an intimacy perspective (of drone filming) in the qualification of quiet areas....

  2. Upscaling of integrated photoelectrochemical water-splitting devices to large areas

    Science.gov (United States)

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-09-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm2 comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis.

  3. Upscaling of integrated photoelectrochemical water-splitting devices to large areas

    Science.gov (United States)

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-01-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm2 comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis. PMID:27601181

  4. Apparatus and method for selective area deposition of thin films on electrically biased substrates

    Science.gov (United States)

    Zuhr, Raymond A.; Haynes, Tony E.; Golanski, Andrzej

    1994-01-01

    An ion beam deposition process for selective area deposition on a polarized substrate uses a potential applied to the substrate which allows the ionized particles to reach into selected areas for film deposition. Areas of the substrate to be left uncoated are held at a potential that repells the ionized particles.

  5. Large-Area Permanent-Magnet ECR Plasma Source

    Science.gov (United States)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired because it is associated with erosion and contamination. The electron temperature is low and does not vary appreciably with power.

  6. Determination of the area density and composition of alloy film using dual alpha particle energy loss

    Science.gov (United States)

    Ma, Xiaojun; Li, Bo; Gao, Dangzhong; Xu, Jiayun; Tang, Yongjian

    2017-02-01

    A novel method based on dual α-particles energy loss (DAEL) is proposed for measuring the area density and composition of binary alloy films. In order to obtain a dual-energy α-particles source, an ingenious design that utilizes the transmitted α-particles traveling the thin film as a new α-particles source is presented. Using the DAEL technique, the area density and composition of Au/Cu film are determined accurately with an uncertainty of better than 10%. Finally, some measures for improving the combined uncertainty are discussed.

  7. Wavy channel Thin Film Transistor for area efficient, high performance and low power applications

    KAUST Repository

    Hanna, Amir

    2014-06-01

    We report a new Thin Film Transistor (TFT) architecture that allows expansion of the device width using wavy (continuous without separation) fin features - termed as wavy channel (WC) architecture. This architecture allows expansion of transistor width in a direction perpendicular to the substrate, thus not consuming extra chip area, achieving area efficiency. The devices have shown for a 13% increase in the device width resulting in a maximum 2.4x increase in \\'ON\\' current value of the WCTFT, when compared to planar devices consuming the same chip area, while using atomic layer deposition based zinc oxide (ZnO) as the channel material. The WCTFT devices also maintain similar \\'OFF\\' current value, similar to 100 pA, when compared to planar devices, thus not compromising on power consumption for performance which usually happens with larger width devices. This work offers a pragmatic opportunity to use WCTFTs as backplane circuitry for large-area high-resolution display applications without any limitation any TFT materials.

  8. Wide-area thin film metal-semiconductor-metal photodetectors for lidar applications

    Science.gov (United States)

    Morrison, Charles B.; Glinz, Andreas P.; Zhu, Zheng; Bechtel, James H.; Frimel, Steven M.; Roenker, Kenneth P.

    1998-04-01

    Novel interdigitated metal-semiconductor-metal structures offer new approaches for the development of broad-area, high-speed photodetectors to be used in optical free space communications and light detection and ranging applications. Inherent advantages include: lower capacitance than typical p-i-n structures, a wide dynamic range, and ease of fabrication. We have constructed broad area metal- semiconductor-metal photodetectors (MSM-PDs) by means of epitaxial liftoff and grafting technologies. Two computer models have been used to examine the effects of design parameters on the performance of broad-area, high-speed MSM- PD devices. The first model indicates that inverting the membrane so that the electrodes are placed between the non- conducting host substrate and the semiconductor material improves the signal-to-noise ration of the device, expanding its dynamic range. This model suggests that processing of the backside of the semiconductor material with antireflection coatings further improves device performance. Carrier collection behavior described by the second model suggests new electrode configurations for improved high speed operation which can only be applied to an inverted MSM-PD carried on a thin film membrane. A number of different fully passivated large area MSM-PD configurations have been fabricated and tested. Initial dark current data are compared favorably to published results.

  9. Wavy channel thin film transistor architecture for area efficient, high performance and low power displays

    KAUST Repository

    Hanna, Amir

    2013-12-23

    We demonstrate a new thin film transistor (TFT) architecture that allows expansion of the device width using continuous fin features - termed as wavy channel (WC) architecture. This architecture allows expansion of transistor width in a direction perpendicular to the substrate, thus not consuming extra chip area, achieving area efficiency. The devices have shown for a 13% increase in the device width resulting in a maximum 2.5× increase in \\'ON\\' current value of the WCTFT, when compared to planar devices consuming the same chip area, while using atomic layer deposition based zinc oxide (ZnO) as the channel material. The WCTFT devices also maintain similar \\'OFF\\' current value, ~100 pA, when compared to planar devices, thus not compromising on power consumption for performance which usually happens with larger width devices. This work offers an interesting opportunity to use WCTFTs as backplane circuitry for large-area high-resolution display applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Rupture mechanism of liquid crystal thin films realized by large-scale molecular simulations

    Science.gov (United States)

    Nguyen, Trung Dac; Carrillo, Jan-Michael Y.; Matheson, Michael A.; Brown, W. Michael

    2014-02-01

    The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented large-scale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top of thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism independent of initial thickness and LC orientational ordering. We further demonstrate that the primary driving force for rupture is closely related to the tendency of the LC mesogens to recover their local environment in the bulk state. Our study not only provides new insights into the rupture mechanism of liquid crystal films, but also sets the stage for future investigations of thin film systems using peta-scale molecular dynamics simulations.The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented large-scale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top of thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism

  11. Saturn: A large area X-ray simulation accelerator

    Science.gov (United States)

    Bloomquist, D. D.; Stinnett, R. W.; McDaniel, D. H.; Lee, J. R.; Sharpe, A. W.; Halbleib, J. A.; Schlitt, L. G.; Spence, P. W.; Corcoran, P.

    1987-06-01

    Saturn is the result of a major metamorphosis of the Particle Beam Fusion Accelerator-I (PBFA-I) from an ICF research facility to the large-area X-ray source of the Simulation Technology Laboratory (STL) project. Renamed Saturn, for its unique multiple-ring diode design, the facility is designed to take advantage of the numerous advances in pulsed power technology. Saturn will include significant upgrades in the energy storage and pulse-forming sections. The 36 magnetically insulated transmission lines (MITLs) that provided power flow to the ion diode of PBFA-I were replaced by a system of vertical triplate water transmission lines. These lines are connected to three horizontal triplate disks in a water convolute section. Power will flow through an insulator stack into radial MITLs that drive the three-ring diode. Saturn is designed to operate with a maximum of 750 kJ coupled to the three-ring e-beam diode with a peak power of 25 TW to provide an X-ray exposure capability of 5 x 10 rads/s (Si) and 5 cal/g (Au) over 500 cm.

  12. Large-area nanogap plasmon resonator arrays for plasmonics applications

    Science.gov (United States)

    Jin, Mingliang; van Wolferen, Henk; Wormeester, Herbert; van den Berg, Albert; Carlen, Edwin T.

    2012-07-01

    Large-area (~8000 mm2) Au nanogap plasmon resonator array substrates manufactured using maskless laser interference lithography (LIL) with high uniformity are presented. The periodically spaced subwavelength nanogap arrays are formed between adjacent nanopyramid (NPy) structures with precisely defined pitch and high length density (~1 km cm-2), and are ideally suited as scattering sites for surface enhanced Raman scattering (SERS), as well as refractive index sensing. The two-dimensional grid arrangement of NPy structures renders the excitation of the plasmon resonators minimally dependent on the incident polarization. The SERS average enhancement factor (AEF) has been characterized using over 30 000 individual measurements of benzenethiol (BT) chemisorbed on the Au NPy surfaces. From the 1(a1), βCCC + νCS ring mode (1074 cm-1) of BT on surfaces with pitch λg = 200 nm, AEF = 0.8 × 106 and for surfaces with λg = 500 nm, AEF = 0.3 × 107 from over 99% of the imaged spots. Maximum AEFs > 108 have been measured in both cases.

  13. Fast restoration of large area breakdown for power distribution systems

    Institute of Scientific and Technical Information of China (English)

    LIU Jian; XU Jing-qiu; CHENG Hong-li

    2006-01-01

    An adjacent table-based simplified model of distribution networks containing medium voltage buses of a substation is established.Identification of bus outage and the condition to start fast restoration procedure are discussed.A complex load shading parameter is set up to describe various load shading schemes.The imaginary part of the load shading parameter describes the states of switches of load shading schemes while the real part is the corresponding amount of shaded load.A new concept of independent tripping operation is also put forward.The procedure to search the operation with the least amount of shaded load for a feeder and a connected domain are detailed.The procedure for fast restoration of a large area breakdown of the whole distribution network under emergency states is dealt with using a typical grid distribution network as an example.Results of analysis show that the direct load shading scheme under the most balanced topology is not always the optimal scheme.The proposed method can obtain the optimal operating mode with the least amount of shaded load thus showing its feasibility.

  14. The Spitzer-HETDEX Exploratory Large-Area Survey

    CERN Document Server

    Papovich, Casey; Mehrtens, N; Lanham, C; Lacy, M; Ciardullo, R; Finkelstein, S L; Bassett, R; Behroozi, P; Blanc, G A; de Jong, R S; DePoy, D L; Drory, N; Gawiser, E; Gebhardt, K; Gronwall, C; Hill, G J; Hopp, U; Jogee, S; Kawinwanichakij, L; Marshall, J L; McLinden, E; Cooper, E Mentuch; Somerville, R S; Steinmetz, M; Tran, K -V; Tuttle, S; Viero, M; Wechsler, R; Zeimann, G

    2016-01-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 micron with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers $\\sim$deg$^2$ of the Sloan Digital Sky Survey "Stripe 82" region, and falls within the footprints of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R $\\sim$ 800 spectroscopy will produce $\\sim$ 200,000 redshifts from the Lyman-$\\alpha$ emission for galaxies in the range 1.9 < z < 3.5, and an additional $\\sim$200,000 redshifts from the [OII] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, AGN, and environment over a co-moving volume of $\\sim$0.5 Gpc$^3$ at 1.9 < z < 3.5. Here, we discuss the properties o...

  15. FERMI LARGE AREA TELESCOPE OBSERVATION OF SUPERNOVA REMNANT S147

    Energy Technology Data Exchange (ETDEWEB)

    Katsuta, J.; Uchiyama, Y.; Tanaka, T.; Tajima, H.; Bechtol, K.; Funk, S.; Lande, J. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d' Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Hanabata, Y. [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Lemoine-Goumard, M. [Universite Bordeaux 1, CNRS/IN2p3, Centre d' Etudes Nucleaires de Bordeaux Gradignan, 33175 Gradignan (France); Takahashi, T., E-mail: katsuta@slac.stanford.edu, E-mail: uchiyama@slac.stanford.edu [Institute of Space and Astronautical Science, Japanese Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2012-06-20

    We present an analysis of gamma-ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope in the region around supernova remnant (SNR) S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) Multiplication-Sign 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 Multiplication-Sign 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with the prominent H{alpha} filaments of SNR S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. The reacceleration of the pre-existing cosmic rays and subsequent adiabatic compression in the filaments is sufficient to provide the energy density required of high-energy protons.

  16. Large area CNT-Si heterojunction for photodetection

    Science.gov (United States)

    Aramo, C.; Ambrosio, M.; Bonavolontà, C.; Boscardin, M.; Crivellari, M.; de Lisio, C.; Grossi, V.; Maddalena, P.; Passacantando, M.; Valentino, M.

    2017-02-01

    Multiwall carbon nanotubes (MWCNTs) consist of multiple layers of graphite sheets arranged in concentric cylinders, from two to many tens. These systems are closely related to graphite layers but in some features, MWCNTs behave quite differently from graphite. In particular, their ability to generate a photocurrent in a wide wavelength range has been demonstrated either without or with the application of a draining voltage. In addition, the photocurrent signal has been found to reproduce the optical absorbance of MWCNTs, showing a maximum in the near UV region. In this paper main characteristics of a novel large area photodetector featuring low noise, high linearity and efficiency are reported. This detector has been obtained by coupling the optoelectronic characteristics of MWCNTs with the well-known properties of silicon. MWCNTs are growth on n-doped silicon layer by chemical vapour deposition creating a p-n heterojunction with high sensitivity to the radiation from UV to IR. An additional MIS junction is obtained with a metallic conductive layer deposited on the back of silicon substrate. Moreover, first results on the signals generated by pulsed laser are also reported.

  17. Calibration of large area Micromegas using cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Loesel, Philipp; Biebel, Otmar; Bortfeldt, Jonathan; Flierl, Bernhard; Hertenberger, Ralf; Mueller, Ralph [LMU Muenchen (Germany); Zibell, Andre [JMU Wuerzburg (Germany)

    2016-07-01

    The high luminosity upgrade of the LHC storage ring implies an upgrade of the Muon Spectrometer of the ATLAS experiment. The presently installed detectors of the inner end-cap region cannot cope with the increased background situation and will be replaced by Micromegas and sTGC detectors. Before installation at CERN, the 2 m{sup 2} sized Micromegas quadruplets (SM2) built in Germany will be calibrated. The LMU Cosmic Ray Measurement Facility (CRF) consists of two Monitored Drift Tube chambers (MDT) with an active area of about 9 m{sup 2} for muon tracking and two trigger hodoscopes with sub-ns time-resolution and with additional position information along the wires of the MDTs. With an angular acceptance of -30 to +30 the CRF allows for centroidal or μTPC position determination and thus for calibration in three dimensions. Of particular interest are potential deviations in the micro pattern readout structures or potential deformations of the whole detector. The Performance of the CRF is presently investigated using a telescope of a 1 m{sup 2} and three 100 cm{sup 2} resistive strip Micromegas. We report on the differences in performance between large and small detectors, report on homogeneity of efficiency and pulse height, and present results on deformation and performance of the 1 m{sup 2} Micromegas.

  18. A Prototype Large Area Detector Module for Muon Scattering Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Steer, C.A.; Boakes, J.; Burns, J.; Snow, S.; Stapleton, M.; Thompson, L.F.; Quillin, S. [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

    2015-07-01

    Abstract-Shielded special nuclear materials (SNM) are of concern as some fissile isotopes have low gamma and neutron emission rates. These materials are also easily shielded to the point where their passive emissions are comparable to background. Consequently, shielded SNM is very challenging for passive radiation detection portals which scan cargo containers. One potential solution for this is to utilise the natural cosmic ray muon background and examine how these muons scatter from materials inside the container volume, terms; the muon scattering tomography (MST) technique measures the three-dimensional localised scattering at all points within a cargo container, providing a degree of material discrimination. There is the additional benefit that the MST signal increases with the presence of more high density shielding materials, in contrast to passive radiation detection. Simulations and calculations suggest that the effectiveness of the technique is sensitive to the tracking accuracy amongst other parameters, motivating the need to develop practical detector systems that are capable of tracking cosmic ray muons. To this end, we have constructed and tested a 2 m by 2 m demonstration module based on gaseous drift chambers and triggered by a large area scintillator-based detector, which is readout by wavelength shifting fibres. We discuss its design, construction, characterisation and operational challenges. (authors)

  19. Recent advances in very large area avalanche photodiodes

    Science.gov (United States)

    Squillante, Michael R.; Christian, James; Entine, Gerald; Farrell, Richard; Karger, Arieh M.; McClish, Mickel; Myers, Richard; Shah, Kanai S.; Taylor, David; Vanderpuye, Kofi; Waer, Peter; Woodring, Mitchell

    2003-09-01

    The Avalanche Photodiode (APD) is a unique device that combines the advantages of solid state photodetectors with those of high gain devices such as photomultiplier tubes (PMTs). APDs have internal gain that provides a high signal-to-noise ratio. APDs have high quantum efficiency, are fast, compact, and rugged. These properties make them suitable detectors for important applications such as LADAR, detection and identification toxic chemicals and bio-warfare agents, LIDAR fluorescence detection, stand-off laser induced breakdown spectroscopy (LIBS), and nuclear detectors and imagers. Recently there have been significant technical breakthroughs in fabricating very large APDs, APD arrays, and position sensitive APD arrays (PSAPD). Signal gain of over 10,000 has been achieved, single element APDs have been fabricated with active area greater than 40 cm2, monolithic pixelated arrays with up to 28 x 28 elements have been fabricated, and position sensitive APDs have been developed and tested. Additionally, significant progress has been made in improving the fabrication process to provide better uniformity and high yield, permitting cost effective manufacturing of APDs for reduced cost.

  20. Fermi Large Area Telescope Operations: Progress Over 4 Years

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, Robert A.; /SLAC

    2012-06-28

    The Fermi Gamma-ray Space Telescope was launched into orbit in June 2008, and is conducting a multi-year gamma-ray all-sky survey, using the main instrument on Fermi, the Large Area Telescope (LAT). Fermi began its science mission in August 2008, and has now been operating for almost 4 years. The SLAC National Accelerator Laboratory hosts the LAT Instrument Science Operations Center (ISOC), which supports the operation of the LAT in conjunction with the Mission Operations Center (MOC) and the Fermi Science Support Center (FSSC), both at NASA's Goddard Space Flight Center. The LAT has a continuous output data rate of about 1.5 Mbits per second, and data from the LAT are stored on Fermi and transmitted to the ground through TDRS and the MOC to the ISOC about 10 times per day. Several hundred computers at SLAC are used to process LAT data to perform event reconstruction, and gamma-ray photon data are subsequently delivered to the FSSC for public release with a few hours of being detected by the LAT. We summarize the current status of the LAT, and the evolution of the data processing and monitoring performed by the ISOC during the first 4 years of the Fermi mission, together with future plans for further changes to detected event data processing and instrument operations and monitoring.

  1. Searches for Dark Matter with the Fermi Large Area Telescope

    CERN Document Server

    CERN. Geneva

    2016-01-01

    The nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments. Among indirect search techniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of the gamma-ray sky have come to prominence over the last few years, because of the excellent sensitivity and full-sky coverage of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope mission. The LAT energy range from 20 MeV to above 300 GeV is particularly well suited for searching for products of the interactions of dark matter particles. In this talk I will describe targets studied for evidence of dark matter with the LAT, and review the status of searches performed with up to six years of LAT data. I will also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, c...

  2. ATTRIBUTION AND CHARACTERISATION OF SCLEROPHYLL FORESTED LANDSCAPES OVER LARGE AREAS

    Directory of Open Access Journals (Sweden)

    S. Jones

    2016-06-01

    Full Text Available This paper presents a methodology for the attribution and characterisation of Sclerophyll forested landscapes over large areas. First we define a set of woody vegetation data primitives (e.g. canopy cover, leaf area index (LAI, bole density, canopy height, which are then scaled-up using multiple remote sensing data sources to characterise and extract landscape woody vegetation features. The advantage of this approach is that vegetation landscape features can be described from composites of these data primitives. The proposed data primitives act as building blocks for the re-creation of past woody characterisation schemes as well as allowing for re-compilation to support present and future policy and management and decision making needs. Three main research sites were attributed; representative of different sclerophyll woody vegetated systems (Box Iron-bark forest; Mountain Ash forest; Mixed Species foothills forest. High resolution hyperspectral and full waveform LiDAR data was acquired over the three research sites. At the same time, land management agencies (Victorian Department of Environment, Land Water and Planning and researchers (RMIT, CRC for Spatial Information and CSIRO conducted fieldwork to collect structural and functional measurements of vegetation, using traditional forest mensuration transects and plots, terrestrial lidar scanning and high temporal resolution in-situ autonomous laser (VegNet scanners. Results are presented of: 1 inter-comparisons of LAI estimations made using ground based hemispherical photography, LAI 2200 PCA, CI-110 and terrestrial and airborne laser scanners; 2 canopy height and vertical canopy complexity derived from airborne LiDAR validated using ground observations; and, 3 time-series characterisation of land cover features. 1. Accuracy targets for remotely sensed LAI products to match within ground based estimates are ± 0.5 LAI or a 20% maximum (CEOS/GCOS with new aspirational targets of 5%. In this

  3. Attribution and Characterisation of Sclerophyll Forested Landscapes Over Large Areas

    Science.gov (United States)

    Jones, Simon; Soto-Berelov, Mariela; Suarez, Lola; Wilkes, Phil; Woodgate, Will; Haywood, Andrew

    2016-06-01

    This paper presents a methodology for the attribution and characterisation of Sclerophyll forested landscapes over large areas. First we define a set of woody vegetation data primitives (e.g. canopy cover, leaf area index (LAI), bole density, canopy height), which are then scaled-up using multiple remote sensing data sources to characterise and extract landscape woody vegetation features. The advantage of this approach is that vegetation landscape features can be described from composites of these data primitives. The proposed data primitives act as building blocks for the re-creation of past woody characterisation schemes as well as allowing for re-compilation to support present and future policy and management and decision making needs. Three main research sites were attributed; representative of different sclerophyll woody vegetated systems (Box Iron-bark forest; Mountain Ash forest; Mixed Species foothills forest). High resolution hyperspectral and full waveform LiDAR data was acquired over the three research sites. At the same time, land management agencies (Victorian Department of Environment, Land Water and Planning) and researchers (RMIT, CRC for Spatial Information and CSIRO) conducted fieldwork to collect structural and functional measurements of vegetation, using traditional forest mensuration transects and plots, terrestrial lidar scanning and high temporal resolution in-situ autonomous laser (VegNet) scanners. Results are presented of: 1) inter-comparisons of LAI estimations made using ground based hemispherical photography, LAI 2200 PCA, CI-110 and terrestrial and airborne laser scanners; 2) canopy height and vertical canopy complexity derived from airborne LiDAR validated using ground observations; and, 3) time-series characterisation of land cover features. 1. Accuracy targets for remotely sensed LAI products to match within ground based estimates are ± 0.5 LAI or a 20% maximum (CEOS/GCOS) with new aspirational targets of 5%). In this research we

  4. Metal Oxide Thin Film Growth by Laser Ablation and Its Applications in High Surface Area Photoanodes

    Science.gov (United States)

    Ghosh, Rudresh

    Thin films are widely used in various applications, including but not limited to simple reflective coatings for mirrors, electrodes for lithium batteries, conducting substrates for electronic circuits, gas sensors and solar cells. As the scope of their applications has widened over the years so has the need to obtain different structural motifs for thin films. A large variety of fabrication techniques are commonly employed to obtain these structures. Pulsed laser deposition (PLD) can be used to obtain films varying from extremely compact and only a few angstroms thick to micron thick porous structures. In this dissertation I introduce a model for predicting different structures as a function of laser parameters and deposition environments in a pulsed laser deposition system. This is followed by a comparison of simulated and experimentally obtained structures. I then use this model to obtain tailored structures suited for individual applications. One of the unique structures obtained using the PLD consists of vertically-aligned structures with nanoparticles as their building blocks. I investigate the superiority of this unique structure over random nanoparticle networks as photoanodes for titanium dioxide (TiO 2)-based dye-sensitized solar cells (DSSC). UV-Vis studies show that there is a 1.4 x enhancement of surface area for PLD-TiO2 photoanodes compared to the best sol-gel films. PLD-TiO2 incident photon to current efficiency (IPCE) values are comparable to 3 x thicker sol-gel films and nearly 92% absorbed photon to current efficiency (APCE) values have been observed for optimized structures. I also examine the suitability of PLD-synthesized niobium oxide (Nb2O5) and tantalum-doped titanium oxide (Ta: TiO2) as photoanode materials. For optimized PLD-Nb2 O5 based DSSCs IPCE values up to 40%, APCE values around 90% and power conversion efficiency of 2.41% were obtained. DSSCs made of PLD-Ta:TiO2 show enhanced photocurrents as well photo efficiency over those based

  5. Sensing sheets based on large area electronics for fatigue crack detection

    Science.gov (United States)

    Yao, Yao; Glisic, Branko

    2015-03-01

    Reliable early-stage damage detection requires continuous structural health monitoring (SHM) over large areas of structure, and with high spatial resolution of sensors. This paper presents the development stage of prototype strain sensing sheets based on Large Area Electronics (LAE), in which thin-film strain gauges and control circuits are integrated on the flexible electronics and deposited on a polyimide sheet that can cover large areas. These sensing sheets were applied for fatigue crack detection on small-scale steel plates. Two types of sensing-sheet interconnects were designed and manufactured, and dense arrays of strain gauge sensors were assembled onto the interconnects. In total, four (two for each design type) strain sensing sheets were created and tested, which were sensitive to strain at virtually every point over the whole sensing sheet area. The sensing sheets were bonded to small-scale steel plates, which had a notch on the boundary so that fatigue cracks could be generated under cyclic loading. The fatigue tests were carried out at the Carleton Laboratory of Columbia University, and the steel plates were attached through a fixture to the loading machine that applied cyclic fatigue load. Fatigue cracks then occurred and propagated across the steel plates, leading to the failure of these test samples. The strain sensor that was close to the notch successfully detected the initialization of fatigue crack and localized the damage on the plate. The strain sensor that was away from the crack successfully detected the propagation of fatigue crack based on the time history of measured strain. Overall, the results of the fatigue tests validated general principles of the strain sensing sheets for crack detection.

  6. Large area growth and electrical properties of p-type WSe2 atomic layers.

    Science.gov (United States)

    Zhou, Hailong; Wang, Chen; Shaw, Jonathan C; Cheng, Rui; Chen, Yu; Huang, Xiaoqing; Liu, Yuan; Weiss, Nathan O; Lin, Zhaoyang; Huang, Yu; Duan, Xiangfeng

    2015-01-14

    Transition metal dichacogenides represent a unique class of two-dimensional layered materials that can be exfoliated into single or few atomic layers. Tungsten diselenide (WSe(2)) is one typical example with p-type semiconductor characteristics. Bulk WSe(2) has an indirect band gap (∼ 1.2 eV), which transits into a direct band gap (∼ 1.65 eV) in monolayers. Monolayer WSe(2), therefore, is of considerable interest as a new electronic material for functional electronics and optoelectronics. However, the controllable synthesis of large-area WSe(2) atomic layers remains a challenge. The studies on WSe(2) are largely limited by relatively small lateral size of exfoliated flakes and poor yield, which has significantly restricted the large-scale applications of the WSe(2) atomic layers. Here, we report a systematic study of chemical vapor deposition approach for large area growth of atomically thin WSe(2) film with the lateral dimensions up to ∼ 1 cm(2). Microphotoluminescence mapping indicates distinct layer dependent efficiency. The monolayer area exhibits much stronger light emission than bilayer or multilayers, consistent with the expected transition to direct band gap in the monolayer limit. The transmission electron microscopy studies demonstrate excellent crystalline quality of the atomically thin WSe(2). Electrical transport studies further show that the p-type WSe(2) field-effect transistors exhibit excellent electronic characteristics with effective hole carrier mobility up to 100 cm(2) V(-1) s(-1) for monolayer and up to 350 cm(2) V(-1) s(-1) for few-layer materials at room temperature, comparable or well above that of previously reported mobility values for the synthetic WSe(2) and comparable to the best exfoliated materials.

  7. MONITORING OF LARGE INSTABLE AREAS: system reliability and new tools.

    Science.gov (United States)

    Leandro, G.; Mucciarelli, M.; Pellicani, R.; Spilotro, G.

    2009-04-01

    The monitoring of unstable or potentially unstable areas is a necessary operation every time you can not remove the conditions of risk and apply to mitigation measures. In Italian Apennine regions there are many urban or extra-urban areas affected by instability, for which it is impracticable to remove hazard conditions, because of size and cost problems. The technological evolution exportable to the field of land instability monitoring is particularly lively and allows the use of warning systems unthinkable just few years ago. However, the monitoring of unstable or potentially unstable areas requires a very great knowledge of the specific problems, without which the reliability of the system may be dangerously overestimated. The movement may arise, indeed, in areas not covered by instrumentation, or covered with vegetation that prevents the acquisition of both reflected signals in the multi-beam laser techniques and radar signals. Environmental conditions (wind, concentrated sources of light, temperature changes, presence of animals) may also invalidate the accuracy of the measures, by introducing modulations or disturbance at a level well above the threshold of alarm signal, leading consequently to raise the values of the warning threshold. The Authors have gained long experience with the observation and monitoring of some large landslides in the Southern Apennine (Aliano, Buoninventre, Calciano, Carlantino, etc.) and unstable areas also at regional scale. One of the most important experiences is about the case of landslides of extensive areas, where unstable and stables zones coexist along transverse and longitudinal axis. In many of these cases you need the accurate control of the movement at selected points to evaluate the trend of displacement velocity, which can be achieved by means of a single-beam laser. The control of these movements, however, does not provide information on stress pattern into the stable areas. Among the sensitive precursors, acoustic

  8. Exploring Milkyway Halo Substructures with Large-Area Sky Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ting [Texas A & M Univ., College Station, TX (United States)

    2016-01-01

    Over the last two decades, our understanding of the Milky Way has been improved thanks to large data sets arising from large-area digital sky surveys. The stellar halo is now known to be inhabited by a variety of spatial and kinematic stellar substructures, including stellar streams and stellar clouds, all of which are predicted by hierarchical Lambda Cold Dark Matter models of galaxy formation. In this dissertation, we first present the analysis of spectroscopic observations of individual stars from the two candidate structures discovered using an M-giant catalog from the Two Micron All-Sky Survey. The follow-up observations show that one of the candidates is a genuine structure which might be associated with the Galactic Anticenter Stellar Structure, while the other one is a false detection due to the systematic photometric errors in the survey or dust extinction in low Galactic latitudes. We then presented the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first-year data of the Dark Energy Survey (DES) – a five-year, 5,000 deg2 optical imaging survey in the Southern Hemisphere. The Eridanus-Phoenix (EriPhe) overdensity is centered around l ~ 285° and b ~ -60° and the Poisson significance of the detection is at least 9σ. The EriPhe overdensity has a cloud-like morphology and the extent is at least ~ 4 kpc by ~ 3 kpc in projection, with a heliocentric distance of about d ~ 16 kpc. The EriPhe overdensity is morphologically similar to the previously-discovered Virgo overdensity and Hercules-Aquila cloud. These three overdensities lie along a polar plane separated by ~ 120° and may share a common origin. In addition to the scientific discoveries, we also present the work to improve the photometric calibration in DES using auxiliary calibration systems, since the photometric errors can cause false detection in first the halo substructure. We present a detailed description of the two

  9. Large Area Fabrication of Semiconducting Phosphorene by Langmuir-Blodgett Assembly

    Science.gov (United States)

    Kaur, Harneet; Yadav, Sandeep; Srivastava, Avanish. K.; Singh, Nidhi; Schneider, Jörg J.; Sinha, Om. P.; Agrawal, Ved V.; Srivastava, Ritu

    2016-01-01

    Phosphorene is a recently new member of the family of two dimensional (2D) inorganic materials. Besides its synthesis it is of utmost importance to deposit this material as thin film in a way that represents a general applicability for 2D materials. Although a considerable number of solvent based methodologies have been developed for exfoliating black phosphorus, so far there are no reports on controlled organization of these exfoliated nanosheets on substrates. Here, for the first time to the best of our knowledge, a mixture of N-methyl-2-pyrrolidone and deoxygenated water is employed as a subphase in Langmuir-Blodgett trough for assembling the nanosheets followed by their deposition on substrates and studied its field-effect transistor characteristics. Electron microscopy reveals the presence of densely aligned, crystalline, ultra-thin sheets of pristine phosphorene having lateral dimensions larger than hundred of microns. Furthermore, these assembled nanosheets retain their electronic properties and show a high current modulation of 104 at room temperature in field-effect transistor devices. The proposed technique provides semiconducting phosphorene thin films that are amenable for large area applications. PMID:27671093

  10. Long-lived ultrafast spin precession in manganese alloys films with a large perpendicular magnetic anisotropy.

    Science.gov (United States)

    Mizukami, S; Wu, F; Sakuma, A; Walowski, J; Watanabe, D; Kubota, T; Zhang, X; Naganuma, H; Oogane, M; Ando, Y; Miyazaki, T

    2011-03-18

    Spin precession with frequencies up to 280 GHz is observed in Mn(3-δ)Ga alloy films with a perpendicular magnetic anisotropy constant K(u)∼15  M erg/cm(3). The damping constant α, characterizing macroscopic spin relaxation and being a key factor in spin-transfer-torque systems, is not larger than 0.008 (0.015) for the δ=1.46 (0.88) film. Those are about one-tenth of α values for known materials with large K(u). First-principles calculations well describe both low α and large K(u) for these alloys.

  11. Wrinkling of extensional thin films through modified large deflection equations analytically and experimentally

    Directory of Open Access Journals (Sweden)

    M.-H. R. Jen

    2015-12-01

    Full Text Available The stretch-induced wrinkling of thin films is solved through the modified von Kármán large deflection equations by first selecting the suitable deformation expressions that satisfy boundary conditions. Then, adopting the principle of minimum potential energy we obtain the deformations of simply supported rectangular thin films. The obtained significant deflections are nonlinearly elastic and of the lowest order of infinite solutions. The parameters of aspect ratio, the thickness and material of thin films are studied analytically and numerically. The highlighted results of wrinkle amplitude and load are in good agreement with experiments. The methodology also indicates the limit load impending plasticity and predicts the applied load precisely for each wrinkle. Further, it can be extended to the variety of multifunctional orthotropic and multi-layered thin films.

  12. Thick and hard anodized aluminum film with large pores for surface composites

    Institute of Scientific and Technical Information of China (English)

    WANG Hui; WANG Hao-wei

    2004-01-01

    Al-base surface self-lubricating composites need thick and hard alumina membranes with large pores to add lubricants easily. This kind of porous alumina layer was fabricated in additive-containing, phosphoric acid-based solution. The effects of additive containing organic carboxylic acid and Ce salt on the properties of the oxide film and mechanism were investigated in detail with SEM and EDAX analyses. The results show that the pore diameter is about 100 nm, the film thickness increases by 4 -5 times, and the Vickers hardness improves by about 50% through adding some amount of organic carboxylic acid and Ce salt. Such an improvement in properties is explained in terms of a lower film dissolving velocity and better film quality in compound solution.

  13. Evaluating biodiversity conservation around a large Sumatran protected area.

    Science.gov (United States)

    Linkie, Matthew; Smith, Robert J; Zhu, Yu; Martyr, Deborah J; Suedmeyer, Beth; Pramono, Joko; Leader-Williams, Nigel

    2008-06-01

    Many of the large, donor-funded community-based conservation projects that seek to reduce biodiversity loss in the tropics have been unsuccessful. There is, therefore, a need for empirical evaluations to identify the driving factors and to provide evidence that supports the development of context-specific conservation projects. We used a quantitative approach to measure, post hoc, the effectiveness of a US$19 million Integrated Conservation and Development Project (ICDP) that sought to reduce biodiversity loss through the development of villages bordering Kerinci Seblat National Park, a UNESCO World Heritage Site in Indonesia. We focused on the success of the ICDP component that disbursed a total of US$1.5 million through development grants to 66 villages in return for their commitment to stop illegally clearing the forest. To investigate whether the ICDP lowered deforestation rates in focal villages, we selected a subset of non-ICDP villages that had similar physical and socioeconomic features and compared their respective deforestation rates. Village participation in the ICDP and its development schemes had no effect on deforestation. Instead, accessible areas where village land-tenure had been undermined by the designation of selective-logging concessions tended to have the highest deforestation rates. Our results indicate that the goal of the ICDP was not met and, furthermore, suggest that both law enforcement inside the park and local property rights outside the park need to be strengthened. Our results also emphasize the importance of quantitative approaches in helping to inform successful and cost-effective strategies for tropical biodiversity conservation.

  14. Large area local anesthesia (LALA) in submuscular breast augmentation.

    Science.gov (United States)

    Parker, Wendy L; Charbonneau, Roland

    2004-01-01

    Large area local anesthesia (LALA) has been recommended for decreasing localized pain and shortening discharge time after breast augmentation surgery. However, quantifiable, objective outcome data for evaluation of the effectiveness of LALA in aesthetic plastic surgery procedures have not yet been reported. We conducted a retrospective patient chart review to determine whether irrigation of the submuscular pocket with bupivacaine in retropectoral breast augmentation procedures quantifiably alters the patient's postoperative course with respect to narcotic requirement, nausea and vomiting, and time to discharge. The findings were evaluated in the context of a critical review of the literature dealing with pain management after breast augmentation, and in particular with the use of LALA. All procedures were performed by the senior author in a private surgical facility. All patients received an identical general anesthetic plus local infiltration of incisions with 1% lidocaine with epinephrine. An inframammary approach was used in all cases; retropectoral dissection was performed with electrocautery dissection followed by hemostasis. In one cohort of patients the submuscular pocket was irrigated with 10 mL of 0.125% bupivacaine before dissection of the contralateral side; in a second control cohort it was not. Postoperative care was the same for both groups. We found a trend toward decreased nausea and vomiting and narcotic use, and a statistically significant decrease in time to discharge, for the cohort that received intraoperative bupivacaine irrigation. LALA is an effective means to decrease recovery time and possibly postoperative pain, nausea and vomiting, and narcotic requirements. Because evidence-based medicine is the surest basis for clinical decisions, evaluation of LALA as well as other treatment modalities should include quantifiable outcome measures.

  15. In situ catalytic growth of large-area multilayered graphene/MoS2 heterostructures

    Science.gov (United States)

    Fu, Wei; Du, Fei-Hu; Su, Juan; Li, Xin-Hao; Wei, Xiao; Ye, Tian-Nan; Wang, Kai-Xue; Chen, Jie-Sheng

    2014-04-01

    Stacking various two-dimensional atomic crystals on top of each other is a feasible approach to create unique multilayered heterostructures with desired properties. Herein for the first time, we present a controlled preparation of large-area graphene/MoS2 heterostructures via a simple heating procedure on Mo-oleate complex coated sodium sulfate under N2 atmosphere. Through a direct in situ catalytic reaction, graphene layer has been uniformly grown on the MoS2 film formed by the reaction of Mo species with S pecies, which is from the carbothermal reduction of sodium sulfate. Due to the excellent graphene ``painting'' on MoS2 atomic layers, the significantly shortened lithium ion diffusion distance and the markedly enhanced electronic conductivity, these multilayered graphene/MoS2 heterostructures exhibit high specific capacity, unprecedented rate performance and outstanding cycling stability, especially at a high current density, when used as an anode material for lithium batteries. This work provides a simple but efficient route for the controlled fabrication of large-area multilayered graphene/metal sulfide heterostructures with promising applications in battery manufacture, electronics or catalysis.

  16. Heteroepitaxial formation of aligned mesostructured silica films with large structural periodicities from mixed surfactant systems.

    Science.gov (United States)

    Hayase, Saeko; Kanno, Yosuke; Watanabe, Masatoshi; Takahashi, Masahiko; Kuroda, Kazuyuki; Miyata, Hirokatsu

    2013-06-11

    Liquid-crystal phases consisting of cylindrical micelles of amphiphilic block copolymers and silica precursors are epitaxially built up on aligned surface micelles formed by an alkyl-PEO surfactant, Brij56, irrespective of the large difference in the intrinsic structural periodicities resulting in the formation of fully aligned mesostructured silica films with large lattice constants. Brij56 works as an alignment controlling agent on rubbing-treated polyimide through selective adsorption from a precursor solution containing the two surfactants, a block copolymer and Brij56, through strong hydrophobic interactions to form an anisotropic surface micelle structure. Aligned mesostructured silica layers with larger periodicities, which dominantly consist of block copolymers, form on these aligned surface micelles by gradually changing the vertical periodicity keeping the lateral intermicelle distance constant. This can be regarded as a kind of heteroepitaxy because the lattice constant at the surface is different from that of the bulk of the film. On the basis of this new concept, highly aligned mesostructured silica films with structural periodicities as large as 10 nm are successfully formed, which has never been achieved when the block copolymers are used alone as the structure-directing agent. The periodicity of the aligned films can precisely be controlled by an appropriate choice of block copolymers and the mixing ratio of the two surfactants, which increases the opportunity for applications of these films with highly anisotropic mesoscale structure.

  17. Area and energy efficient high-performance ZnO wavy channel thin-film transistor

    KAUST Repository

    Hanna, Amir

    2014-09-01

    Increased output current while maintaining low power consumption in thin-film transistors (TFTs) is essential for future generation large-area high-resolution displays. Here, we show wavy channel (WC) architecture in TFT that allows the expansion of the transistor width in the direction perpendicular to the substrate through integrating continuous fin features on the underlying substrate. This architecture enables expanding the TFT width without consuming any additional chip area, thus enabling increased performance while maintaining the real estate integrity. The experimental WCTFTs show a linear increase in output current as a function of number of fins per device resulting in (3.5×) increase in output current when compared with planar counterparts that consume the same chip area. The new architecture also allows tuning the threshold voltage as a function of the number of fin features included in the device, as threshold voltage linearly decreased from 6.8 V for planar device to 2.6 V for WC devices with 32 fins. This makes the new architecture more power efficient as lower operation voltages could be used for WC devices compared with planar counterparts. It was also found that field effect mobility linearly increases with the number of fins included in the device, showing almost \\\\(1.8×) enhancements in the field effect mobility than that of the planar counterparts. This can be attributed to higher electric field in the channel due to the fin architecture and threshold voltage shift. © 2014 IEEE.

  18. Large-area alignment of tungsten oxide nanowires over flat and patterned substrates for room-temperature gas sensing.

    Science.gov (United States)

    Cheng, Wei; Ju, Yanrui; Payamyar, Payam; Primc, Darinka; Rao, Jingyi; Willa, Christoph; Koziej, Dorota; Niederberger, Markus

    2015-01-02

    Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single-crystalline ultrathin W18 O49 nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, and, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir-Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H2 at room temperature.

  19. The Large Area Detector of LOFT: the Large Observatory for X-ray Timing

    CERN Document Server

    Zane, S; Kennedy, T; Feroci, M; Herder, J -W Den; Ahangarianabhari, M; Argan, A; Azzarello, P; Baldazzi, G; Barbera, M; Barret, D; Bertuccio, G; Bodin, P; Bozzo, E; Bradley, L; Cadoux, F; Cais, P; Campana, R; Coker, J; Cros, A; Del Monte, E; De Rosa, A; Di Cosimo, S; Donnarumma, I; Evangelista, Y; Favre, Y; Feldman, C; Fraser, G; Fuschino, F; Grassi, M; Hailey, M R; Hudec, R; Labanti, C; Macera, D; Malcovati, P; Marisaldi, M; Martindale, A; Mineo, T; Muleri, F; Nowak, M; Orlandini, M; Pacciani, L; Perinati, E; Petracek, V; Pohl, M; Rachevski, A; Smith, P; Santangelo, A; Seyler, J -Y; Schmid, C; Soffitta, P; Suchy, S; Tenzer, C; Uttley, P; Vacchi, A; Zampa, G; Zampa, N; Wilms, J; Winter, B

    2014-01-01

    LOFT (Large Observatory for X-ray Timing) is one of the five candidates that were considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. Its pointed instrument is the Large Area Detector (LAD), a 10 m 2 -class instrument operating in the 2-30keV range, which holds the capability to revolutionise studies of variability from X-ray sources on the millisecond time scales. The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most of the trade-offs have been closed leading to a robust and well documented design that will be re- proposed in future ESA calls. In this talk, we will summarize the characteristics of the LAD design and give an overview of the expectations for the instrument capabilities.

  20. Using elemental Pb surface as a precursor to fabricate large area CH3NH3PbI3 perovskite solar cells

    Science.gov (United States)

    He, Yingying; Lei, Yan; Yang, Xiaogang; Lu, Kai; Liu, Songzi; Gu, Longyan; Zheng, Zhi

    2016-12-01

    The development of new chemical methods to prepare large area perovskite thin film solar cells is desirable for potential future industrial applications. In this paper, a novel fabrication of perovskite CH3NH3PbI3 thin films based on direct metal surface elemental reaction (DMSER) method in an ambient atmosphere is discussed. The as-prepared CH3NH3PbI3 thin films are highly pure and crystalline. Consequent Transient photovoltaic (TPV) tests were conducted and show that these thin films have a long minority carrier lifetime as good as the perovskite thin films obtained via common two-step method from the literature. Although there have been many studies that have developed perovskite solar cells (PSCs) during the past five years, the current study is the first report using elemental Pb as a precursor to fabricate perovskite solar cells, which were found to be relatively stable upon storage without encapsulation in glove box for more than 200 days. This Pb-initiated in-situ reaction allows for the fabrication of large area and uniform perovskite thin films. For example, in our preliminary studies, we have fabricated large area solar cell device samples (1.10 ± 0.05 cm2) and have evaluated their photovoltaic performance under standard conditions (AM 1.5, 100 mW cm-2).

  1. Robust large-gap quantum spin Hall insulators in chemically decorated arsenene films

    Science.gov (United States)

    Wang, Dongchao; Chen, Li; Shi, Changmin; Wang, Xiaoli; Cui, Guangliang; Zhang, Pinhua; Chen, Yeqing

    2016-03-01

    Based on first-principles calculations, we propose one new category of two-dimensional topological insulators (2D TIs) in chemically functionalized (-CH3 and -OH) arsenene films. The results show that the surface decorated arsenene (AsCH3 and AsOH) films are intrinsic 2D TIs with sizeable bulk gap. The bulk energy gaps are 0.184 eV, and 0.304 eV in AsCH3 and AsOH films, respectively. Such large bulk gaps make them suitable to realize quantum spin Hall effect in an experimentally accessible temperature regime. Topologically helical edge states in these systems are desirable for dissipationless transport. Moreover, we find that the topological properties in these systems are robust against mechanical deformation by exerting biaxial strain. These novel 2D TIs with large bulk gaps are potential candidate in future electronic devices with ultralow dissipation.

  2. Large negative Goos-H(a)nchen shift from a wedge-shaped thin film

    Institute of Scientific and Technical Information of China (English)

    Jianping Bai; Yaoju Zhang

    2009-01-01

    The analytical expression for the complex amplitude of light reflected from a wedge-shaped thin film is derived.For plane wave incidence,a simple ray tracing approach is used to calculate Goos-H(a)nchen(GH)shifts;and for non-plane wave incidence,for example,a Gaussian beam,the angular spectrum approach of plane wave is used in simulation.The two approaches predict that a wedge-shaped thin film can produce large negative longitudinal GH shifts.Although the reflectivity is small near the condition of resonance,the large negative GH shifts can be more easily detected in comparison with the shift from a plane-paxallel film in vacuum.

  3. Applications of large-area nanopatterning to energy generation and storage devices

    Science.gov (United States)

    Mills, Eric N.

    This dissertation encompasses the creation and testing of nanostructured, electrochemically-active energy generation and storage devices, and development of the associated fabrication techniques. The fabricated devices include nanopatterned, plasmonically-active, TiO2+Au thin films for Photocatalytic Water Splitting (PCW), TiO2-based Dye-Sensitized Solar Cells (DSSCs) incorporating nanopatterned, plasmonically-active metallic front electrodes, and Si nanopillar anodes for Li-ion batteries. Techniques were also developed for encapsulation and removal of wet-etched Si nanowires from their mother substrates. TiO2 was the first material to be widely used for PCW. Its use is hampered by its large bandgap (~3.2eV), and poor recombination lifetimes. Au nanoparticles (NPs) have been previously used to improve recombination lifetimes in TiO2 by separating photogenerated carriers near the NP edges, and to increase photocurrents by injecting plasmonically-excited hot electrons into the TiO2 conduction band. Using nanostructured TiO 2+Au electrodes, we aim to increase the PCW efficiency of TiO2 -based electrodes. Dye-sensitized solar cells (DSSCs) employ visible-absorbing dyes anchored to a high-surface-area semiconducting scaffold. The front transparent conducting electrode (TCE) is typically ITO, a scarce and expensive material. We aim to increase the efficiency of thin-film DSSCs and eliminate the use of ITO by using a metallic subwavelength array (MESH) of nanoholes as the front TCE. Silicon holds promise as a high-capacity anode material for Li-ion batteries, as it can store ~10x the Li of graphite, the current leading anode material (3569 vs. 372 mAh/g). However, Si undergoes dramatic (>300%) volume expansion upon "lithiation", pulverizing any structure with non-nanoscopic dimensions (>250nm). We created large-area arrays of "nanopillars" with sub-100nm diameters, using roll-to-roll-compatible flexible-mold NIL on commercially-available metal substrates. Ordered

  4. Selective area growth of Bi2Te3 and Sb2Te3 topological insulator thin films

    Science.gov (United States)

    Kampmeier, Jörn; Weyrich, Christian; Lanius, Martin; Schall, Melissa; Neumann, Elmar; Mussler, Gregor; Schäpers, Thomas; Grützmacher, Detlev

    2016-06-01

    The intrinsic bulk behavior of topological insulators (TI) is a key issue for their employment in future device applications. State of the art TIs predominantly suffer from large bulk charge carrier concentrations that mask their extraordinary surface states. In this paper we present the selective area growth of Bi2Te3 and Sb2Te3 TI thin films on prestructured Si(111) Si on insulator (SOI) substrates, paving the way to high quality TI nanostructures in which access to surface states is enhanced. Therefore high quality Bi2Te3 and Sb2Te3 thin films were deposited by means of solid source molecular beam epitaxy (MBE) and subsequently investigated by energy dispersive x-ray spectroscopy (EDX). To investigate the transport properties of the selectively grown thin films, magnetotransport measurements were performed at low temperatures. Nucleation in the SiO2 valleys next to the prepatterned Si(111) mesa structures was not observed. The structural and morphological qualities of crystals deposited on untreated Si(111) SOI wafers are completely preserved by employing the selective area growth on prepatterned substrates. The transport characteristics of the selectively-grown TI systems are comparable to those of the analogous postpatterned films.

  5. Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics

    Science.gov (United States)

    Bucella, Sadir G.; Luzio, Alessandro; Gann, Eliot; Thomsen, Lars; McNeill, Christopher R.; Pace, Giuseppina; Perinot, Andrea; Chen, Zhihua; Facchetti, Antonio; Caironi, Mario

    2015-09-01

    High-mobility semiconducting polymers offer the opportunity to develop flexible and large-area electronics for several applications, including wearable, portable and distributed sensors, monitoring and actuating devices. An enabler of this technology is a scalable printing process achieving uniform electrical performances over large area. As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics. By combining pre-aggregating solvents for formulating the semiconductor and by adopting a room temperature wired bar-coating technique, here we demonstrate the fast deposition of submonolayers and nanostructured films of a model electron-transporting polymer. Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm2 V-1 s-1, allowing very simple device architectures to operate at 3.3 MHz. Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

  6. Large Area Deposition of MoS2 by Pulsed Laser Deposition with In-Situ Thickness Control

    KAUST Repository

    Serna, Martha I.

    2016-05-24

    A scalable and catalyst-free method to deposit stoichiometric Molybdenum Disulfide (MoS2) films over large areas is reported with the maximum area limited by the size of the substrate holder. The method allows deposition of MoS2 layers on a wide range of substrates without any additional surface preparation including single crystals (sapphire and quartz), polycrystalline (HfO2), and amorphous (SiO2). The films are deposited using carefully designed MoS2 targets fabricated with excess of sulfur (S) and variable MoS2 and S particle size. Uniform and layered MoS2 films as thin as two monolayers, with an electrical resistivity of 1.54 × 104 Ω cm-1 were achieved. The MoS2 stoichiometry was as confirmed by High Resolution Rutherford Backscattering Spectrometry (HRRBS). With the method reported here, in situ graded MoS2 films ranging from ~1 to 10 monolayers can also be deposited.

  7. Large-Area Deposition of MoS2 by Pulsed Laser Deposition with In Situ Thickness Control.

    Science.gov (United States)

    Serna, Martha I; Yoo, Seong H; Moreno, Salvador; Xi, Yang; Oviedo, Juan Pablo; Choi, Hyunjoo; Alshareef, Husam N; Kim, Moon J; Minary-Jolandan, Majid; Quevedo-Lopez, Manuel A

    2016-06-28

    A scalable and catalyst-free method to deposit stoichiometric molybdenum disulfide (MoS2) films over large areas is reported, with the maximum area limited by the size of the substrate holder. The method allows deposition of MoS2 layers on a wide range of substrates without any additional surface preparation, including single-crystal (sapphire and quartz), polycrystalline (HfO2), and amorphous (SiO2) substrates. The films are deposited using carefully designed MoS2 targets fabricated with excess sulfur and variable MoS2 and sulfur particle size. Uniform and layered MoS2 films as thin as two monolayers, with an electrical resistivity of 1.54 × 10(4) Ω cm(-1), were achieved. The MoS2 stoichiometry was confirmed by high-resolution Rutherford backscattering spectrometry. With the method reported here, in situ graded MoS2 films ranging from ∼1 to 10 monolayers can be deposited.

  8. Atomically flat Ge buffer layers and alternating shutter growth of CaGe2 for large area germanane

    Science.gov (United States)

    Xu, Jinsong; Katoch, Jyoti; Ahmed, Adam; Pinchuk, Igor; Williams, Robert; McComb, David; Kawakami, Roland

    Germanane (GeH), which is converted from CaGe2 by soaking in HCl acid, has recently attracted interest because of its novel properties, such as large band gap (1.56eV), spin orbit coupling and predictions of high mobility (18000 cm2/Vs). Previously CaGe2 was successfully grown on Ge(111) substrates by molecular beam epitaxy (MBE) growth. But there were cracks between µm-sized islands, which is not desirable for scientific study and application, and limits the material quality. By growing atomically flat Ge buffer layers and using alternating shutter MBE growth, we are able to grow crack-free, large area films of CaGe2 films. Reflection high energy electron diffraction (RHEED) patterns of Ge buffer layer and CaGe2 indicates high quality two dimensional surfaces, which is further confirmed by atomic force microscopy (AFM), showing atomically flat and uniform Ge buffer layer and CaGe2. The appearance of Laue oscillation in X-ray diffraction (XRD) and Kiessig fringes in X-ray reflectivity (XRR) proves the uniformity of CaGe2 film and the smoothness of the interface. The high quality of CaGe2 film makes it promising to explore novel properties of GeH. Funded by NSF MRSEC DMR-1420451.

  9. Unexpected large room-temperature ferromagnetism in porous Cu{sub 2}O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xue [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Liu, Lihu; Jia, Xiaoxuan; Liu, Huiyuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-05-15

    Porous Cu{sub 2}O films have been fabricated on porous anodic alumina substrates using DC-reactive magnetron sputtering with pure Cu targets, and unexpectedly large room temperature ferromagnetism has been observed in the films. The maximum saturation magnetic moment along the out-of-plane direction was as high as 94 emu/cm{sup 3}. Photoluminescence spectra show that the ferromagnetism originates with oxygen vacancies. The ferromagnetism could be adjusted by changing the concentration of oxygen vacancies through annealing in an oxygen atmosphere. These observations suggest that the origin of the ferromagnetism is due to coupling between oxygen vacancies with local magnetic moments in the porous Cu{sub 2}O films, which can occur either directly through exchange interactions between oxygen vacancies, or through the mediation of conduction electrons. Such a ferromagnet without the presence of any ferromagnetic dopant may find applications in spintronic devices. - Highlights: • Porous Cu{sub 2}O films were deposited on porous anodic alumina (PAA) substrates. • Significant room-temperature ferromagnetism has been observed in porous Cu{sub 2}O films. • Ferromagnetism of Cu{sub 2}O films exhibited different magnetic signals with the field. • The saturation magnetization is 94 emu/cm{sup 3} with an out-of-plane.

  10. NOTE: Study of Gafchromic® EBT film response over a large dose range

    Science.gov (United States)

    Martišíková, Mária; Jäkel, Oliver

    2010-05-01

    Presently Gafchromic EBT films are widely used for relative dose verification in standard radiation therapy using high-energy photons, inclusive IMRT. The use of films for dosimetry in medical ion beams is more complicated due to the strongly inhomogeneous dose deposition by ions on microscopic level. Track structure models, presently used to describe dosimeter response as a function of the ion field properties, are based on input information which can be obtained from the film response in photon beams. We therefore studied the performance of Gafchromic EBT films, ancestors of currently available EBT2 films, in 60Co photon beams. The dose-response curve was measured from 7.5 × 10-2 Gy to 3 × 104 Gy. The dynamic range, linearity and dose rate dependence of this calibration curve were studied. A high saturation dose of 3 × 103 Gy, and thus a large dynamic range, was observed. No signs of supralinearity and bleaching due to radiation were found. No dependence of the response on the dose rate at high dose rates and high doses was found. All those properties justify the use of simplified models of the film response to ions. Furthermore, fits of the calibration data by predictions of different models for signal creation mechanism of dosimetric materials were performed. The best description was found for the recently published gamma-distributed single-hit model which takes into account different sizes of the active centres.

  11. Columnar structured FePt films epitaxially grown on large lattice mismatched intermediate layer

    Science.gov (United States)

    Dong, K. F.; Deng, J. Y.; Peng, Y. G.; Ju, G.; Chow, G. M.; Chen, J. S.

    2016-09-01

    The microstructure and magnetic properties of the FePt films grown on large mismatched ZrN (15.7%) intermediate layer were investigated. With using ZrN intermediate layer, FePt 10 nm films exhibited (001) texture except for some weaker FePt (110) texture. Good epitaxial relationships of FePt (001) //ZrN (001) //TiN (001) among FePt and ZrN/TiN were revealed from the transmission electron microscopy (TEM) results. As compared with TiN intermediate layer, although FePt-SiO2-C films grown on ZrN/TiN intermediate layer showed isotropic magnetic properties, the large interfacial energy and lattice mismatch between FePt and ZrN would lead to form columnar structural FePt films with smaller grain size and improved isolation. By doping ZrN into the TiN layer, solid solution of ZrTiN was formed and the lattice constant is increased comparing with TiN and decreased comparing with ZrN. Moreover, FePt-SiO2-C films grown on TiN 2 nm-20 vol.% ZrN/TiN 3 nm intermediate layer showed an improved perpendicular magnetic anisotropy. Simultaneously, columnar structure with smaller grain size retained.

  12. Large area controlled assembly of transparent conductive networks

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Simpson, John T.

    2015-09-29

    A method of preparing a network comprises disposing a solution comprising particulate materials in a solvent onto a superhydrophobic surface comprising a plurality of superhydrophobic features and interfacial areas between the superhydrophobic features. The plurality of superhydrophobic features has a water contact angle of at least about 150.degree.. The method of preparing the network also comprises removing the solvent from the solution of the particulate materials, and forming a network of the particulate materials in the interfacial areas, the particulate materials receding to the interfacial areas as the solvent is removed.

  13. Large Mode Area Yb-Doped Photonic Bandgap Fiber Lasers

    Science.gov (United States)

    2015-02-08

    effective area of 1450 ?m2 was fabricated using the stack and draw technique (Figure 1). The microstructures in the cladding are comprised of germanium...doped silica. A low refractive index polymer coating provides a numerical aperture of 0.46 for pumping purposes. 1. REPORT DATE (DD-MM-YYYY) 4...and a calculated effective area of 1450 ?m2 was fabricated using the stack and draw technique (Figure 1). The microstructures in the cladding are

  14. Large-eddy simulation of an offshore Mediterranean area

    DEFF Research Database (Denmark)

    Rizza, Umberto; Miglietta, Mario M.; Sempreviva, Anna Maria;

    2014-01-01

    in order to optimize the structural design of offshore large wind turbines that today reach heights up to 200 m. Large-eddy simulations (LESs) have been performed and compared with offshore experimental data collected during the LASIE campaign performed in the Mediterranean during summer 2007. Two...... simulations are performed: one where the LES is left free to evolve without any external forcing, and one where a force restoration nudging technique has been implemented in LES in order to force the model to the evolving large-scale situation. Model results have been compared against experimental soundings....... Results show that for all the calculated fields the nudged LES outperforms the simulation without nudging, demonstrating that incorporating changes in the large-scale features is necessary in order to provide a realistic evolution of the modelled meteorological fields at local scale. Thus, appropriately...

  15. Four large coastal upwelling areas are created by eastern boundary ...

    African Journals Online (AJOL)

    spamer

    A balanced trophic flow model of the southern Benguela ecosystem is presented, averaging the period. 1980–1989 ...... similar to that of benthic carnivorous fish, a weighted diet was ...... its positive effect as anchovy prey was largely counter-.

  16. Bend-Induced Distortion in Large Mode Area Holey Fibre

    Institute of Scientific and Technical Information of China (English)

    TAN Xiao-Ling; GENG You-Fu; ZHANG Tie-Li; WANG Wei-Neng; WANG Peng; YAO Jian-Quan

    2008-01-01

    A simplified scheme of bend-induced mode distortion is introduced into bent holey fibres,the distorted mode distribution and mode effective area reduction are investigated using the finite difference method.Numerical results show that the modes of bent holey fibres with small bend radius shift away from the core and are deformed greatly,and the mode areas drop significantly as the bend radius decreases,which severely affects the fibre laser performance.The propagation characteristics of bent holey fibres at given wavelength are determined by fill factor and normalized bend radius.Finally,the transition normalized bend radius that represents the location of the mode area beginning to fall off is obtained.

  17. Large-area few-layer MoS 2 deposited by sputtering

    KAUST Repository

    Huang, Jyun-Hong

    2016-06-06

    Direct magnetron sputtering of transition metal dichalcogenide targets is proposed as a new approach for depositing large-area two-dimensional layered materials. Bilayer to few-layer MoS2 deposited by magnetron sputtering followed by post-deposition annealing shows superior area scalability over 20 cm(2) and layer-by-layer controllability. High crystallinity of layered MoS2 was confirmed by Raman, photo-luminescence, and transmission electron microscopy analysis. The sputtering temperature and annealing ambience were found to play an important role in the film quality. The top-gate field-effect transistor by using the layered MoS2 channel shows typical n-type characteristics with a current on/off ratio of approximately 10(4). The relatively low mobility is attributed to the small grain size of 0.1-1 mu m with a trap charge density in grain boundaries of the order of 10(13) cm(-2).

  18. Small- and Large-scale Characterization and Mixing Properties in a Thermally Driven Thin Liquid Film

    CERN Document Server

    Winkler, Michael

    2015-01-01

    Thin liquid films are nanoscopic elements of foams, emulsions and suspensions, and form a paradigm for nanochannel transport that eventually test the limits of hydrodynamic descriptions. Here we use classical dynamical systems characteristics to study the complex interplay of thermal convection, interface and gravitational forces which yields turbulent mixing and transport: Lyapunov exponents and entropies. We induce a stable two eddy convection in an extremely thin liquid film by applying a temperature gradient. Experimentally, we determine the small-scale dynamics using the motion and deformation of spots of equal size/equal color, we dubbed that technique "color imaging velocimetry". The large-scale dynamics is captured by encoding the left/right motion of the liquid directed to the left or right of the separatrix between the two rolls. This way, we characterize chaos of course mixing in this peculiar fluid geometry of a thin, free-standing liquid film.

  19. Theory of Multifarious Quantum Phases and Large Anomalous Hall Effect in Pyrochlore Iridate Thin Films.

    Science.gov (United States)

    Hwang, Kyusung; Kim, Yong Baek

    2016-07-15

    We theoretically investigate emergent quantum phases in the thin film geometries of the pyrochore iridates, where a number of exotic quantum ground states are proposed to occur in bulk materials as a result of the interplay between electron correlation and strong spin-orbit coupling. The fate of these bulk phases as well as novel quantum states that may arise only in the thin film platforms, are studied via a theoretical model that allows layer-dependent magnetic structures. It is found that the magnetic order develop in inhomogeneous fashions in the thin film geometries. This leads to a variety of magnetic metal phases with modulated magnetic ordering patterns across different layers. Both the bulk and boundary electronic states in these phases conspire to promote unusual electronic properties. In particular, such phases are akin to the Weyl semimetal phase in the bulk system and they would exhibit an unusually large anomalous Hall effect.

  20. Large area solar power heliostat array for OSETI

    Science.gov (United States)

    Covault, Corbin E.

    2001-08-01

    Current OSETI programs make use of optical telescopes with light collection areas on the order of 10 square meters or less. The small collection area limits the ultimate sensitivity achievable to low-intensity signals. However, solar power facilities such as the National Solar Thermal Test Facility (NSTTF) provide the potential for a much larger collecting area. The NSTTF is operated at by the Department of Energy at Sandia National Laboratories for research in solar power development and testing. The NSTTF site includes over 200 fully steerable mirrors (called heliostats) each providing 37 square meters of collecting area. This facility is currently being used at night for gamma-ray astronomy. The STACEE experiment makes use of 64 heliostats to detect nanosecond flashes of optical Cherenkov light associated with gamma-ray air showers from the top of the atmosphere. The STACEE experiment has been in operation since 1998 and has already detected gamma-rays from the Crab Nebula. In principle, the STACEE experiment can be operated with minor modifications to detect OSETI signals on the ground at a photon density of less than two optical photons per square meter per pulse. We summarize performance results from the STACEE experiment, and we discuss the sensitivity of a hypothetical future STACEE-OSETI experiment with particular attention to potential sources of background.

  1. Characterization of large area nanostructured surfaces using AFM measurements

    DEFF Research Database (Denmark)

    Calaon, Matteo; Hansen, Hans Nørgaard; Tosello, Guido;

    2012-01-01

    magnitude of the 3D surface amplitude parameters chosen for the analysis, when increasing the Al purity from 99,5% to 99,999%. AFM was then employed to evaluate the periodical arrangements of the nano structured cells. Image processing was used to estimate the average areas value, the height variation...

  2. Large-area perovskite nanowire arrays fabricated by large-scale roll-to-roll micro-gravure printing and doctor blading

    Science.gov (United States)

    Hu, Qiao; Wu, Han; Sun, Jia; Yan, Donghang; Gao, Yongli; Yang, Junliang

    2016-02-01

    Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ~45%, temperature ~28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays with great potential applications in flexible electronic and optoelectronic devices.Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ~45%, temperature ~28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays

  3. Engineering Chemically Exfoliated Large-Area Two-Dimensional MoS2 Nanolayers with Porphyrins for Improved Light Harvesting.

    Science.gov (United States)

    Zhang, Hanyu; Choi, Jungwook; Ramani, Arjun; Voiry, Damien; Natoli, Sean N; Chhowalla, Manish; McMillin, David R; Choi, Jong Hyun

    2016-09-19

    Molybdenum disulfide (MoS2 ) is a promising candidate for electronic and optoelectronic applications. However, its application in light harvesting has been limited in part due to crystal defects, often related to small crystallite sizes, which diminish charge separation and transfer. Here we demonstrate a surface-engineering strategy for 2D MoS2 to improve its photoelectrochemical properties. Chemically exfoliated large-area MoS2 thin films were interfaced with eight molecules from three porphyrin families: zinc(II)-, gallium(III)-, iron(III)-centered, and metal-free protoporphyrin IX (ZnPP, GaPP, FePP, H2 PP); metal-free and zinc(II) tetra-(N-methyl-4-pyridyl)porphyrin (H2 T4, ZnT4); and metal-free and zinc(II) tetraphenylporphyrin (H2 TPP, ZnTPP). We found that the photocurrents from MoS2 films under visible-light illumination are strongly dependent on the interfacial molecules and that the photocurrent enhancement is closely correlated with the highest occupied molecular orbital (HOMO) levels of the porphyrins, which suppress the recombination of electron-hole pairs in the photoexcited MoS2 films. A maximum tenfold increase was observed for MoS2 functionalized with ZnPP compared with pristine MoS2 films, whereas ZnT4-functionalized MoS2 demonstrated small increases in photocurrent. The application of bias voltage on MoS2 films can further promote photocurrent enhancements and control current directions. Our results suggest a facile route to render 2D MoS2 films useful for potential high-performance light-harvesting applications.

  4. Absolute indoor calibration of large area solar cells

    Science.gov (United States)

    Metzdorf, J.; Wittchen, T.; Kaase, H.

    1986-11-01

    Equipment for the calibration of reference solar cells which is traceable back to their primary radiometric standards is presented. The apparatus, based on the differential spectral responsivity method is an absolute indoor procedure without reference solar cells, and needs no solar simulator. The method is applicable to all kinds of test devices up to solar cell areas of 10 x 10 cm without any requirements on linearity and spectral responsivity of the cells.

  5. China's first large tanker for icy area successfully launched

    Institute of Scientific and Technical Information of China (English)

    Chen Jianan

    2006-01-01

    @@ On July 10, the 51800 dwt product/chemical tanker developed, designed and built by China for navigating in icy areas was launched at Guangzhou Shipyard International. The tanker is scheduled for delivery at the end of this year. The second follow-on ship will soon be built on the berths. At present, Guangzhou Shipyard International has a backlog order of 11 such tankers.

  6. A Large Area Fiber Optic Gyroscope on multiplexed fiber network

    OpenAIRE

    Clivati, Cecilia; Calonico, Davide; Costanzo, Giovanni A.; Mura, Alberto; Pizzocaro, Marco; Levi, Filippo

    2012-01-01

    We describe a fiber optical gyroscope based on the Sagnac effect realized on a multiplexed telecom fiber network. Our loop encloses an area of 20 km^2 and coexists with Internet data traffic. This Sagnac interferometer achieves a sensitivity of about 1e-8 (rad/s)/sqrt(Hz), thus approaching ring laser gyroscopes without using narrow-linewidth laser nor sophisticated optics. The proposed gyroscope is sensitive enough for seismic applications, opening new possibilities for this kind of optical f...

  7. A Large Area Fiber Optic Gyroscope on multiplexed fiber network

    CERN Document Server

    Clivati, Cecilia; Costanzo, Giovanni A; Mura, Alberto; Pizzocaro, Marco; Levi, Filippo

    2012-01-01

    We describe a fiber optical gyroscope based on the Sagnac effect realized on a multiplexed telecom fiber network. Our loop encloses an area of 20 km^2 and coexists with Internet data traffic. This Sagnac interferometer achieves a sensitivity of about 1e-8 (rad/s)/sqrt(Hz), thus approaching ring laser gyroscopes without using narrow-linewidth laser nor sophisticated optics. The proposed gyroscope is sensitive enough for seismic applications, opening new possibilities for this kind of optical fiber sensors

  8. Self-assembled large-area annular cavity arrays with tunable cylindrical surface plasmons for sensing.

    Science.gov (United States)

    Ni, Haibin; Wang, Ming; Shen, Tianyi; Zhou, Jing

    2015-02-24

    Surface plasmons that propagate along cylindrical metal/dielectric interfaces in annular apertures in metal films, called cylindrical surface plasmons (CSPs), exhibit attractive optical characteristics. However, it is challenging to fabricate these nanocoaxial structures. Here, we demonstrate a practical low-cost route to manufacture highly ordered, large-area annular cavity arrays (ACAs) that can support CSPs with great tunability. By employing a sol-gel coassembly method, reactive ion etching and metal sputtering techniques, regular, highly ordered ACAs in square-centimeter-scale with a gap width tunable in the range of several to hundreds of nanometers have been produced with good reproducibility. Ag ACAs with a gap width of 12 nm and a gap height of 635 nm are demonstrated. By finite-difference time-domain simulation, we confirm that the pronounced dips in the reflectance spectra of ACAs are attributable to CSP resonances excited in the annular gaps. By adjusting etching time and Ag film thickness, the CSP dips can be tuned to sweep the entire optical range of 360 to 1800 nm without changing sphere size, which makes them a promising candidate for forming integrated plasmonic sensing arrays. The high tunability of the CSP resonant frequencies together with strong electric field enhancement in the cavities make the ACAs promising candidates for surface plasmon sensors and SERS substrates, as, for example, they have been used in liquid refractive index (RI) sensing, demonstrating a sensitivity of 1505 nm/RIU and a figure of merit of 9. One of the CSP dips of ACAs with a certain geometry size is angle- (0-70 degrees) and polarization-independent and can be used as a narrow-band absorber. Furthermore, the nano annular cavity arrays can be used to construct solar cells, nanolasers and nanoparticle plasmonic tweezers.

  9. Cosmic ray tests of large area Multigap Resistive Plate Chambers

    CERN Document Server

    An, S; Kim, J; Williams, M C S; Zichichi, A; Zuyeuski, R

    2007-01-01

    We have built Multigap Resistive Plate Chambers (MRPC) with six gas gaps and an active area of . The signals are generated on 2.5 cm wide copper pickup strips; these are read out at each end thus allowing the position of the hit along the strip to be obtained from the time difference. Using three of these chambers we have set up a cosmic tracking system in a similar manner as planned for the Extreme Energy Events (EEE) project. The details of the set-up are presented in this paper. In addition we discuss the time and position resolution of these MRPCs measured using cosmic rays.

  10. Rapid fabrication of large area binary polystyrene colloidal crystals

    Science.gov (United States)

    Luo, Chun-Li; Yang, Rui-Xia; Yan, Wei-Guo; Zhao, Jian; Yang, Guang-Wu; Jia, Guo-Zhi

    2016-07-01

    Binary colloidal crystals (BCCs) possess great potentials in tuning material and optical properties. In this paper, the combination of interface transferred method and spin-coating method is used to fabricate BCCs with different patterns via controlling the size ratio of small (S) to large (L) colloidal spheres and the spin speeds. It is found that BCCs formed LS2, LS4 and LS6 by changing the size ratio. In addition, there are some new and complicated structures, such as LS12, Janus arrays, formed at the low spin speed. This simple assembly method has potential to allow for the creation of optical metmaterials and the plasmonic structures with chiral optical properties.

  11. Large-area magnetic metamaterials via compact interference lithography.

    Science.gov (United States)

    Feth, Nils; Enkrich, Christian; Wegener, Martin; Linden, Stefan

    2007-01-22

    Magnetic metamaterials with magnetic-dipole resonances around 1.2-mum wavelength are fabricated using an extremely compact and robust version of two- or three-beam interference lithography for 1D and 2D structures, respectively. Our approach employs a single laser beam at 532- nm wavelength impinging onto a suitably shaped dielectric object (roof-top prism or pyramid) - bringing the complexity of fabricating magnetic metamaterials down to that of evaporating usual dielectric/metallic coatings.The measured optical spectra agree well with theory; the retrieval reveals a negative magnetic permeability. Importantly, the large-scale sample homogeneity is explicitly demonstrated by optical experiments.

  12. Water-based, nonfluorinated dispersions for environmentally benign, large-area, superhydrophobic coatings.

    Science.gov (United States)

    Schutzius, Thomas M; Bayer, Ilker S; Qin, Jian; Waldroup, Don; Megaridis, Constantine M

    2013-12-26

    Low-cost, large-area, superhydrophobic coating treatments are of high value to technological applications requiring efficient liquid repellency. While many applications are envisioned, only few are realizable in practice due to either the high cost or low durability of such treatments. Recently, spray deposition of polymer-particle dispersions has been demonstrated as an excellent means for producing low-cost, large-area, durable, superhydrophobic composite coatings/films; however, such dispersions generally contain harsh or volatile solvents, which are required for solution processing of polymers as well as for dispersing hydrophobic nanoparticles, thus inhibiting scalability due to the increased cost in chemical handling and environmental safety concerns. Moreover, such coatings usually contain fluoropolymers due to their inherent low surface energy, a requirement for superhydrophobicity, but concerns over their biopersistence has provided an impetus for eliminating these chemicals. For spray coating, the former problem can be overcome by replacing organic solvents with water, but this situation seems paradoxical: Producing a highly water-repellent coating from an aqueous dispersion. We report a water-based, nonfluorinated dispersion for the formation of superhydrophobic composite coatings applied by spray on a variety of substrates. We stabilize hydrophobic components (i.e., polymer, nanoparticles) in water, by utilizing chemicals containing acid functional groups (i.e., acrylic acid) that can become ionized in aqueous environments under proper pH control (pH > 7). The functional polymer utilized in this study is a copolymer of ethylene and acrylic acid, while the particle filler is exfoliated graphite nanoplatelet (xGnP), which contains functional groups at its periphery. Once spray deposited and dried, the components become insoluble in water, thus promoting liquid repellency. Such coatings can find a wide range of applications due to their benign processing

  13. Large area full-field optical coherence tomography

    Science.gov (United States)

    Chang, Shoude; Sherif, Sherif; Flueraru, Costel

    2006-09-01

    Optical Coherence Tomography (OCT) is a fundamentally new type of optical imaging technology. OCT performs high resolution, cross-sectional tomographic imaging of the internal structure in materials and biological systems. The biomedical applications of the OCT imaging systems have been developed for diagnostics of ophthalmology, dermatology, dentistry and cardiology. Most of existing OCT systems use point-scanning based technology, however, the 3-axis scanning makes the system slow and cumbersome. A few OCT systems working directly on 2D full-field images were reported, however, they are designed to work in a relatively small area, around couple of hundred microns square. In this paper, we present a design and implementation of a full-field OCT imaging system for acquiring tomography and with a working area around 15mm by 15 mm. The problems rising from full-field OCT are addressed and analyzed. The algorithms to extract the tomography are proposed. Two applications of multilayer information retrieval and 3D object imaging using full-field OCT are described.

  14. Growth and Characterization of Large Scale (Sb1-xBix)2 Te3 Thin Films on Mica

    Science.gov (United States)

    Ni, Yan; Zhang, Zhen; Jiles, David

    2015-03-01

    Topological insulators (TIs) attract attentions for both fundamental science and potential applications because of their bulk band inversion arising from the strong spin orbital coupling. However, it is necessary to tune the Fermi level and Dirac cone in 3D TI (Sb1-xBix)2 Te3 to make an ideal system for TI applications. In this work, we report high quality (Sb1-xBix)2 Te3 thin films grown on mica substrate by molecular beam epitaxy. The surface roughness of the thin film can reach as low as 0.7 nm in a large area by van der Waals epitaxy. (Sb1-xBix)2 Te3 thin film with x = 0.04 shows a local maxima in the room temperature sheet resistance, which indicates a minimization of the carrier density due to band structure engineering. Moreover, for higher Bi concentration, due to an increase of the surface roughness and corresponding reduction of electron mobility, the sheet resistance increases. Our results on the feasibility of depositing (Sb1-xBix)2 Te3 in wide Bi range on mica substrate will helpful for the application of TI at room temperature and flexible electronics. Authors would like to thank the financial support from the U.S. National Science Foundation under the Award No. 1201883.

  15. Large-area nanopatterned graphene for ultrasensitive gas sensing

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Mackenzie, David Micheal Angus; Tschammer, Lisa Katharina

    2014-01-01

    Chemical vapor deposited (CVD) graphene is nanopatterned using a spherical block copolymer etch mask. The use of spherical rather than cylindrical block copolymers allows homogeneous patterning of cm-scale areas without any substrate surface treatment. Raman spectroscopy was used to study...... the controlled generation of point defects in the graphene lattice with increasing etching time, confirming that alongside the nanomesh patterning, the nanopatterned CVD graphene presents a high defect density between the mesh holes. The nanopatterned samples showed sensitivities for NO2 of more than one order...... of magnitude higher than for non-patterned graphene. NO2 concentrations as low as 300 ppt were detected with an ultimate detection limit of tens of ppt. This is the smallest value reported so far for non-UV illuminated graphene chemiresistive NO2 gas sensors. The dramatic improvement in the gas sensitivity...

  16. Large area magnetic micropallet arrays for cell colony sorting.

    Science.gov (United States)

    Cox-Muranami, Wesley A; Nelson, Edward L; Li, G P; Bachman, Mark

    2016-01-01

    A new micropallet array platform for adherent cell colony sorting has been developed. The platform consisted of thousands of square plastic pallets, 270 μm by 270 μm on each side, large enough to hold a single colony of cells. Each pallet included a magnetic core, allowing them to be collected with a magnet after being released using a microscope mounted laser system. The micropallets were patterned from 1002F epoxy resist and were fabricated on translucent, gold coated microscope slides. The gold layer was used as seed for electroplating the ferromagnetic cores within every individual pallet. The gold layer also facilitated the release of each micropallet during laser release. This array allows for individual observation, sorting and collection of isolated cell colonies for biological cell colony research. In addition to consistent release and recovery of individual colonies, we demonstrated stable biocompatibility and minimal loss in imaging quality compared to previously developed micropallet arrays.

  17. 102ℏk large area atom interferometers.

    Science.gov (United States)

    Chiow, Sheng-wey; Kovachy, Tim; Chien, Hui-Chun; Kasevich, Mark A

    2011-09-23

    We demonstrate atom interferometers utilizing a novel beam splitter based on sequential multiphoton Bragg diffractions. With this sequential Bragg large momentum transfer (SB-LMT) beam splitter, we achieve high contrast atom interferometers with momentum splittings of up to 102 photon recoil momenta (102ℏk). To our knowledge, this is the highest momentum splitting achieved in any atom interferometer, advancing the state-of-the-art by an order of magnitude. We also demonstrate strong noise correlation between two simultaneous SB-LMT interferometers, which alleviates the need for ultralow noise lasers and ultrastable inertial environments in some future applications. Our method is intrinsically scalable and can be used to dramatically increase the sensitivity of atom interferometers in a wide range of applications, including inertial sensing, measuring the fine structure constant, and detecting gravitational waves.

  18. Research on fabrication technology for thin film solar cells for practical use. Research on low-cost fabrication technology for large-area modules (production technology for amorphous silicon solar cell modules); Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu. Daimenseki module no tei cost seizo gijutsu (amorphous taiyo denchi module seizo no gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Tatsuta, M. [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

    1994-12-01

    This paper reports the study results on the fabrication technology of amorphous Si solar cell modules in fiscal 1994. (1) On process technology for prototype film substrate solar cells, an advanced preprocessing equipment for film substrates, stepping roll type film forming technology, and prototype submodules were studied. A conversion efficiency of 7.2% was achieved by use of the submodule formed in an effective region of 40 {times} 40cm{sup 2}. (2) On efficiency improvement technology for film substrate solar cells, p/i and n/i interfaces, forming condition for Ag film electrodes, film thickness of transparent electrode ITO, and optimum transmissivity were studied. (3) On technology for advanced solar cells, high-quality a-SiGe: H film, ion control in plasma CVD, and a-Si film formation by plasma CVD using SiH2Cl2 were studied as production technology of narrow gap materials. (4) On advanced two-layer tandem solar cells, the defect density in optical degradation of a-Si cells by reverse bias dark current was evaluated, and outdoor exposure data were analyzed. 4 figs., 1 tab.

  19. Ultra-stiff large-area carpets of carbon nanotubes

    Science.gov (United States)

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G.; Murdock, Adrian T.; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-01

    Herewith, we report the influence of post-synthesis heat treatment (aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, >=4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.Herewith, we report the influence of post-synthesis heat treatment (aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than

  20. Tools for visualizing landscape pattern for large geographic areas

    Energy Technology Data Exchange (ETDEWEB)

    Timmins, S.P. [Analysas Corporation, Oak Ridge, TN (United States); Hunsaker, C.T. [Oak Ridge National Lab., TN (United States)

    1993-10-01

    Landscape pattern can be modelled on a grid with polygons constructed from cells that share edges. Although this model only allows connections in four directions, programming is convenient because both coordinates and attributes take discrete integer values. A typical raster land-cover data set is a multimegabyte matrix of byte values derived by classification of images or gridding of maps. Each matrix may have thousands of raster polygons (patches), many of them islands inside other larger patches. These data sets have complex topology that can overwhelm vector geographic information systems. The goal is to develop tools to quantify change in the landscape structure in terms of the shape and spatial distribution of patches. Three milestones toward this goal are (1) creating polygon topology on a grid, (2) visualizing patches, and (3) analyzing shape and pattern. An efficient algorithm has been developed to locate patches, measure area and perimeter, and establish patch topology. A powerful visualization system with an extensible programming language is used to write procedures to display images and perform analysis.

  1. Characterization of large-area pressure sensitive robot skin

    Science.gov (United States)

    Saadatzi, Mohammad Nasser; Baptist, Joshua R.; Wijayasinghe, Indika B.; Popa, Dan O.

    2017-05-01

    Sensorized robot skin has considerable promise to enhance robots' tactile perception of surrounding environments. For physical human-robot interaction (pHRI) or autonomous manipulation, a high spatial sensor density is required, typically driven by the skin location on the robot. In our previous study, a 4x4 flexible array of strain sensors were printed and packaged onto Kapton sheets and silicone encapsulants. In this paper, we are extending the surface area of the patch to larger arrays with up to 128 tactel elements. To address scalability, sensitivity, and calibration challenges, a novel electronic module, free of the traditional signal conditioning circuitry was created. The electronic design relies on a software-based calibration scheme using high-resolution analog-to-digital converters with internal programmable gain amplifiers. In this paper, we first show the efficacy of the proposed method with a 4x4 skin array using controlled pressure tests, and then perform procedures to evaluate each sensor's characteristics such as dynamic force-to-strain property, repeatability, and signal-to-noise-ratio. In order to handle larger sensor surfaces, an automated force-controlled test cycle was carried out. Results demonstrate that our approach leads to reliable and efficient methods for extracting tactile models for use in future interaction with collaborative robots.

  2. A large-area RF source for negative hydrogen ions

    Science.gov (United States)

    Frank, P.; Feist, J. H.; Kraus, W.; Speth, E.; Heinemann, B.; Probst, F.; Trainham, R.; Jacquot, C.

    1998-08-01

    In a collaboration with CEA Cadarache, IPP is presently developing an rf source, in which the production of negative ions (H-/D-) is being investigated. It utilizes PINI-size rf sources with an external antenna and for the first step a small size extraction system with 48 cm2 net extraction area. First results from BATMAN (Ba¯varian T_est Ma¯chine for N_egative Ions) show (without Cs) a linear dependence of the negative ion yield with rf power, without any sign of saturation. At elevated pressure (1.6 Pa) a current density of 4.5 mA/cm2 H- (without Cs) has been found so far. At medium pressure (0.6 Pa) the current density is lower by approx. a factor of 5, but preliminary results with Cesium injection show a relative increase by almost the same factor in this pressure range. Langmuir probe measurements indicate an electron temperature Te>2 eV close to the plasma grid with a moderate magnetic filter (700 Gcm). Attempts to improve the performance by using different magnetic configurations and different wall materials are under way.

  3. Large-Area Semiconducting Graphene Nanomesh Tailored by Interferometric Lithography.

    Science.gov (United States)

    Kazemi, Alireza; He, Xiang; Alaie, Seyedhamidreza; Ghasemi, Javad; Dawson, Noel Mayur; Cavallo, Francesca; Habteyes, Terefe G; Brueck, Steven R J; Krishna, Sanjay

    2015-07-01

    Graphene nanostructures are attracting a great deal of interest because of newly emerging properties originating from quantum confinement effects. We report on using interferometric lithography to fabricate uniform, chip-scale, semiconducting graphene nanomesh (GNM) with sub-10 nm neck widths (smallest edge-to-edge distance between two nanoholes). This approach is based on fast, low-cost, and high-yield lithographic technologies and demonstrates the feasibility of cost-effective development of large-scale semiconducting graphene sheets and devices. The GNM is estimated to have a room temperature energy bandgap of ~30 meV. Raman studies showed that the G band of the GNM experiences a blue shift and broadening compared to pristine graphene, a change which was attributed to quantum confinement and localization effects. A single-layer GNM field effect transistor exhibited promising drive current of ~3.9 μA/μm and ON/OFF current ratios of ~35 at room temperature. The ON/OFF current ratio of the GNM-device displayed distinct temperature dependence with about 24-fold enhancement at 77 K.

  4. A large area, silicon photomultiplier-based PET detector module.

    Science.gov (United States)

    Raylman, Rr; Stolin, A; Majewski, S; Proffitt, J

    2014-01-21

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26 × 58 array of 1.5 × 1.5mm(2) LYSO elements (spanning 41 × 91mm(2)) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ∼45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (∼2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3T clinical magnetic resonance imaging scanner.

  5. Large area molybdenum disulphide- epitaxial graphene vertical Van der Waals heterostructures

    Science.gov (United States)

    Pierucci, Debora; Henck, Hugo; Naylor, Carl H.; Sediri, Haikel; Lhuillier, Emmanuel; Balan, Adrian; Rault, Julien E.; Dappe, Yannick J.; Bertran, François; Fèvre, Patrick Le; Johnson, A. T. Charlie; Ouerghi, Abdelkarim

    2016-06-01

    Two-dimensional layered transition metal dichalcogenides (TMDCs) show great potential for optoelectronic devices due to their electronic and optical properties. A metal-semiconductor interface, as epitaxial graphene - molybdenum disulfide (MoS2), is of great interest from the standpoint of fundamental science, as it constitutes an outstanding platform to investigate the interlayer interaction in van der Waals heterostructures. Here, we study large area MoS2-graphene-heterostructures formed by direct transfer of chemical-vapor deposited MoS2 layer onto epitaxial graphene/SiC. We show that via a direct transfer, which minimizes interface contamination, we can obtain high quality and homogeneous van der Waals heterostructures. Angle-resolved photoemission spectroscopy (ARPES) measurements combined with Density Functional Theory (DFT) calculations show that the transition from indirect to direct bandgap in monolayer MoS2 is maintained in these heterostructures due to the weak van der Waals interaction with epitaxial graphene. A downshift of the Raman 2D band of the graphene, an up shift of the A1g peak of MoS2 and a significant photoluminescence quenching are observed for both monolayer and bilayer MoS2 as a result of charge transfer from MoS2 to epitaxial graphene under illumination. Our work provides a possible route to modify the thin film TDMCs photoluminescence properties via substrate engineering for future device design.

  6. Fabrication and Test of Large Area Spider-Web Bolometers for CMB Measurements

    Science.gov (United States)

    Biasotti, M.; Ceriale, V.; Corsini, D.; De Gerone, M.; Gatti, F.; Orlando, A.; Pizzigoni, G.

    2016-08-01

    Detecting the primordial 'B-mode' polarization of the cosmic microwave background is one of the major challenges of modern observational cosmology. Microwave telescopes need sensitive cryogenic bolometers with an overall equivalent noise temperature in the nK range. In this paper, we present the development status of large area (about 1 cm2) spider-web bolometer, which imply additional fabrication challenges. The spider-web is a suspended Si3N4 1 \\upmu m-thick and 8-mm diameter with mesh size of 250 \\upmu m. The thermal sensitive element is a superconducting transition edge sensor (TES) at the center of the bolometer. The first prototype is a Ti-Au TES with transition temperature tuned around 350 mK, new devices will be a Mo-Au bilayer tuned to have a transition temperature of 500 mK. We present the fabrication process with micro-machining techniques from silicon wafer covered with SiO2 - Si3N4 CVD films, 0.3 and 1 \\upmu m- thick, respectively, and preliminary tests.

  7. Holographic three-dimensional telepresence using large-area photorefractive polymer.

    Science.gov (United States)

    Blanche, P-A; Bablumian, A; Voorakaranam, R; Christenson, C; Lin, W; Gu, T; Flores, D; Wang, P; Hsieh, W-Y; Kathaperumal, M; Rachwal, B; Siddiqui, O; Thomas, J; Norwood, R A; Yamamoto, M; Peyghambarian, N

    2010-11-04

    Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted considerable public interest since it was depicted in the original Star Wars film in 1977. However, the lack of sufficient computational power to produce realistic computer-generated holograms and the absence of large-area and dynamically updatable holographic recording media have prevented realization of the concept. Here we use a holographic stereographic technique and a photorefractive polymer material as the recording medium to demonstrate a holographic display that can refresh images every two seconds. A 50 Hz nanosecond pulsed laser is used to write the holographic pixels. Multicoloured holographic 3D images are produced by using angular multiplexing, and the full parallax display employs spatial multiplexing. 3D telepresence is demonstrated by taking multiple images from one location and transmitting the information via Ethernet to another location where the hologram is printed with the quasi-real-time dynamic 3D display. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

  8. Recommendations for Large-scale Farmland Operation in Hilly Areas Based on Long Tail Theory

    Institute of Scientific and Technical Information of China (English)

    Changsheng; QIU; Dingxiang; LIU

    2014-01-01

    At the background of urban and rural integration,this paper analyzed and discussed factors restricting large-scale farmland operation in China’s hilly areas from the qualitative perspective. It recognized large-scale farmland operation on the basis of the long tail theory. Finally,it came up with recommendations for developing large-scale farmland operation in hilly areas.

  9. Selected area laser-crystallized polycrystalline silicon thin films by a pulsed Nd:YAG laser with 355 nm wavelength

    Institute of Scientific and Technical Information of China (English)

    Duan Chunyan; Liu Chao; Ai Bin; Lai Jianjun; Deng Youjun; Shen Hui

    2011-01-01

    Selected area laser-crystallized polycrystalline silicon(p-Si)thin films were prepared by the third harmonics(355 nm wavelength)generated by a solid-state pulsed Nd:YAG laser.Surface morphologies of 400 nm thick films after laser irradiation were analyzed.Raman spectra show that film crystallinity is improved with increase of laser energy.The optimum laser energy density is sensitive to the film thickness.The laser energy density for efficiently crystallizing amorphous silicon films is between 440-634 mJ/cm2 for 300 nm thick films and between 777-993 mJ/cm2 for 400 nm thick films.The optimized laser energy density is 634,975 and 1571 mJ/cm2 for 300,400 and 500 nm thick films,respectively.

  10. Demonstration of large field effect in topological insulator films via a high-κ back gate

    Science.gov (United States)

    Wang, C. Y.; Lin, H. Y.; Yang, S. R.; Chen, K. H. M.; Lin, Y. H.; Chen, K. H.; Young, L. B.; Cheng, C. K.; Fanchiang, Y. T.; Tseng, S. C.; Hong, M.; Kwo, J.

    2016-05-01

    The spintronics applications long anticipated for topological insulators (TIs) has been hampered due to the presence of high density intrinsic defects in the bulk states. In this work we demonstrate the back-gating effect on TIs by integrating Bi2Se3 films 6-10 quintuple layer (QL) thick with amorphous high-κ oxides of Al2O3 and Y2O3. Large gating effect of tuning the Fermi level EF to very close to the band gap was observed, with an applied bias of an order of magnitude smaller than those of the SiO2 back gate, and the modulation of film resistance can reach as high as 1200%. The dependence of the gating effect on the TI film thickness was investigated, and ΔN2D/ΔVg varies with TI film thickness as ˜t-0.75. To enhance the gating effect, a Y2O3 layer thickness 4 nm was inserted into Al2O3 gate stack to increase the total κ value to 13.2. A 1.4 times stronger gating effect is observed, and the increment of induced carrier numbers is in good agreement with additional charges accumulated in the higher κ oxides. Moreover, we have reduced the intrinsic carrier concentration in the TI film by doping Te to Bi2Se3 to form Bi2TexSe1-x. The observation of a mixed state of ambipolar field that both electrons and holes are present indicates that we have tuned the EF very close to the Dirac Point. These results have demonstrated that our capability of gating TIs with high-κ back gate to pave the way to spin devices of tunable EF for dissipationless spintronics based on well-established semiconductor technology.

  11. Direct writing of large-area plasmonic photonic crystals using single-shot interference ablation

    Energy Technology Data Exchange (ETDEWEB)

    Pang Zhaoguang; Zhang Xinping, E-mail: zhangxinping@bjut.edu.cn [Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124 (China)

    2011-04-08

    We report direct writing of metallic photonic crystals (MPCs) through a single-shot exposure of a thin film of colloidal gold nanoparticles to the interference pattern of a single UV laser pulse before a subsequent annealing process. This is defined as interference ablation, where the colloidal gold nanoparticles illuminated by the bright interference fringes are removed instantly within a timescale of about 6 ns, which is actually the pulse length of the UV laser, whereas the gold nanoparticles located within the dark interference fringes remain on the substrate and form grating structures. This kind of ablation has been proven to have a high spatial resolution and thus enables successful fabrication of waveguided MPC structures with the optical response in the visible spectral range. The subsequent annealing process transforms the grating structures consisting of ligand-covered gold nanoparticles into plasmonic MPCs. The annealing temperature is optimized to a range from 250 to 300 deg. C to produce MPCs of gold nanowires with a period of 300 nm and an effective area of 5 mm in diameter. If the sample of the spin-coated gold nanoparticles is rotated by 90{sup 0} after the first exposure, true two-dimensional plasmonic MPCs are produced through a second exposure to the interference pattern. Strong plasmonic resonance and its coupling with the photonic modes of the waveguided MPCs verifies the success of this new fabrication technique. This is the simplest and most efficient technique so far for the construction of large-area MPC devices, which enables true mass fabrication of plasmonic devices with high reproducibility and high success rate.

  12. Thin films of spin-crossover coordination polymers with large thermal hysteresis loops prepared by nanoparticle spin coating.

    Science.gov (United States)

    Tanaka, Daisuke; Aketa, Naoki; Tanaka, Hirofumi; Tamaki, Takashi; Inose, Tomoko; Akai, Tomoki; Toyama, Hirotaka; Sakata, Osami; Tajiri, Hiroo; Ogawa, Takuji

    2014-09-11

    This communication describes the synthesis of spin-crossover nanoparticles, which can disperse in various organic solvents without an excess amount of surfactants. The nanoparticles form homogeneous thin films on substrates by spin coating. The films show abrupt spin transitions with large thermal hysteresis loops.

  13. Locally Resolved Electron Emission Area and Unified View of Field Emission in Nanodiamond Films

    Energy Technology Data Exchange (ETDEWEB)

    Chubenko, Oksana; Baturin, Stanislav S.; Kovi, Kiran Kumar; Sumant, Anirudha V.; Baryshev, Sergey V.

    2017-09-01

    One of the common problems in case of field emission from polycrystalline diamond films, which typically have uniform surface morphology, is uncertainty in determining exact location of electron emission sites across the surface. Although several studies have suggested that grain boundaries are the main electron emission source, it is not particularly clear what makes some sites emit more than the others. It is also practically unclear how one could quantify the actual electron emission area and therefore field emission current per unit area. In this paper we study the effect of actual, locally resolved, field emission (FE) area on electron emission characteristics of uniform planar highly conductive nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) field emitters. It was routinely found that field emission from as-grown planar (N)UNCD films is always confined to a counted number of discrete emitting centers across the surface which varied in size and electron emissivity. It was established that the actual FE area critically depends on the applied electric field, as well as that the actual FE area and the overall electron emissivity improve with sp2 fraction present in the film irrespectively of the original substrate roughness and morphology. To quantify the actual FE area and its dependence on the applied electric field, imaging experiments were carried out in a vacuum system in a parallel-plate configuration with a specialty anode phosphor screen. Electron emission micrographs were taken concurrently with I-V characteristics measurements. In addition, a novel automated image processing algorithm was developed to process extensive imaging datasets and calculate emission area per image. By doing so, it was determined that the emitting area was always significantly smaller than the FE cathode surface area. Namely, the actual FE area would change from 5×10-3 % to 1.5 % of the total cathode area with the applied electric field increased. Finally and most

  14. Large lateral photovoltaic effect observed in nano Al-doped ZnO films.

    Science.gov (United States)

    Lu, Jing; Wang, Hui

    2011-07-18

    Zinc oxide (ZnO), including a variety of metal-doped ZnO, as one kind of most important photoelectric materials, has been widely investigated and received enormous attention for a series of applications. In this work, we report a new finding which we call as lateral photovoltaic effect (LPE) in a nano Al-doped ZnO (ZAO) film based on ZAO/SiO2/Si homo-heterostructure. This large and stable LPE observed in ZAO is an important supplement to the existing ZnO properties. In addition, all data and analyses demonstrate ZAO film can also be a good candidate for new type position-sensitive detector (PSD) devices.

  15. Large negative magnetoresistance in reactive sputtered polycrystalline GdNx films

    KAUST Repository

    Mi, W. B.

    2013-06-07

    Polycrystalline ferromagnetic GdN x films were fabricated at different N2 flow rates ( fN2 ) to modify N-vacancy concentration so as to study its influence on electrotransport. Metal-semiconductor transition appears at Curie temperature (TC ) of ∼40 K. Temperature-dependent magnetoresistance (MR) shows a peak at T C. The films at fN2  = 5, 10, 15, and 20 sccm show MR of −38%, −42%, −46%, and −86% at 5 K and 50 kOe, respectively. Above 15 K, MR is from colossal MR and from both colossal and tunneling MR below 15 K. The enhanced MR at fN2  = 20 sccm is attributed to large spin polarization of half-metallicity in GdN x with low N vacancies.

  16. A hybrid MBE-based growth method for large-area synthesis of stacked hexagonal boron nitride/graphene heterostructures.

    Science.gov (United States)

    Wofford, Joseph M; Nakhaie, Siamak; Krause, Thilo; Liu, Xianjie; Ramsteiner, Manfred; Hanke, Michael; Riechert, Henning; J Lopes, J Marcelo

    2017-02-27

    Van der Waals heterostructures combining hexagonal boron nitride (h-BN) and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. In particular, the growth of h-BN on graphene has proven to be challenging due to the inertness of the graphene surface. Here we exploit a scalable molecular beam epitaxy based method to allow both the h-BN and graphene to form in a stacked heterostructure in the favorable growth environment provided by a Ni(111) substrate. This involves first saturating a Ni film on MgO(111) with C, growing h-BN on the exposed metal surface, and precipitating the C back to the h-BN/Ni interface to form graphene. The resulting laterally continuous heterostructure is composed of a top layer of few-layer thick h-BN on an intermediate few-layer thick graphene, lying on top of Ni/MgO(111). Examinations by synchrotron-based grazing incidence diffraction, X-ray photoemission spectroscopy, and UV-Raman spectroscopy reveal that while the h-BN is relaxed, the lattice constant of graphene is significantly reduced, likely due to nitrogen doping. These results illustrate a different pathway for the production of h-BN/graphene heterostructures, and open a new perspective for the large-area preparation of heterosystems combining graphene and other 2D or 3D materials.

  17. Fabrication of nanoelectromechanical systems via the integration of high surface area glancing angle deposition thin films

    Science.gov (United States)

    Westwood, J. N.; Sauer, V. T. K.; Kwan, J. K.; Hiebert, W. K.; Sit, J. C.

    2014-06-01

    Nanoelectromechanical systems (NEMS) coated with a high surface area thin film are fabricated. Glancing angle deposition (GLAD) is used to uniformly deposit high surface area, nanostructured SiO2 films on top of released NEMS. The resonance frequencies and quality factors are measured to assess the potential of the high surface area NEMS for sensing experiments. Resonance frequencies of coated cantilevers, although reduced by mass loading, can be predicted accurately using our derived model. Compressive stress makes the resonance frequencies of coated doubly-clamped beams difficult to predict. The quality factors of the coated NEMS are reduced by one order of magnitude by a quasi-continuous layer at the base of the GLAD film, which also introduces an estimated compressive stress of 5.3-9.3 MPa. The limit of detection is demonstrated to be ˜2 pg cm-2. With this successful proof-of-concept demonstration, we anticipate the future use of these devices as high surface area gravimetric mass sensors for applications such as gas chromatography.

  18. Large-scale fabrication of In2S3 porous films via one-step hydrothermal process.

    Science.gov (United States)

    Chen, Fei; Deng, Dan; Lei, Yinlin

    2013-10-01

    Large-scale indium sulfide (In2S3) porous films were fabricated via a facile one-step and non-template hydrothermal process using L-cysteine as a capping agent. The impact of reaction conditions such as reaction time, temperatures, and capping agents on the synthesis of the In2S3 porous films were studied. The morphology, structure, and phase composition of In2S3 porous films were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The formation process and the optical property of the In2S3 porous films were also evaluated.

  19. Physical characterization and effect of effective surface area on the sensing properties of tin dioxide thin solid films in a propane atmosphere.

    Science.gov (United States)

    Gómez-Pozos, Heberto; González-Vidal, José Luis; Torres, Gonzalo Alberto; Olvera, María de la Luz; Castañeda, Luis

    2013-12-27

    The physical properties and the effect of effective surface area (ESA) on the sensing properties of tin dioxide [SnO2] thin films in air and propane [C3H8] atmosphere as a function of operating temperature and gas concentration have been studied in this paper. SnO2 thin films with different estimated thicknesses (50, 100 and 200 nm) were deposited on glass substrates by the chemical spray technique. Besides, they were prepared at two different deposition temperatures (400 and 475 °C). Tin chloride [SnCl4∙5H2O] with 0.2 M concentration value and ethanol [C2H6O] were used as tin precursor and solvent, respectively. The morphological, and structural properties of the as-prepared films were analyzed by AFM and XRD, respectively. Gas sensing characteristics of SnO2 thin solid films were measured at operating temperatures of 22, 100, 200, and 300 °C, and at propane concentration levels (0, 5, 50, 100, 200, 300, 400, and 500 ppm). ESA values were calculated for each sample. It was found that the ESA increased with the increasing thickness of the films. The results demonstrated the importance of the achieving of a large effective surface area for improving gas sensing performance. SnO2 thin films deposited by spray chemical were chosen to study the ESA effect on gas sensing properties because their very rough surfaces were appropriate for this application.

  20. Physical Characterization and Effect of Effective Surface Area on the Sensing Properties of Tin Dioxide Thin Solid Films in a Propane Atmosphere

    Directory of Open Access Journals (Sweden)

    Heberto Gómez-Pozos

    2013-12-01

    Full Text Available The physical properties and the effect of effective surface area (ESA on the sensing properties of tin dioxide [SnO2] thin films in air and propane [C3H8] atmosphere as a function of operating temperature and gas concentration have been studied in this paper. SnO2 thin films with different estimated thicknesses (50, 100 and 200 nm were deposited on glass substrates by the chemical spray technique. Besides, they were prepared at two different deposition temperatures (400 and 475 °C. Tin chloride [SnCl4∙5H2O] with 0.2 M concentration value and ethanol [C2H6O] were used as tin precursor and solvent, respectively. The morphological, and structural properties of the as-prepared films were analyzed by AFM and XRD, respectively. Gas sensing characteristics of SnO2 thin solid films were measured at operating temperatures of 22, 100, 200, and 300 °C, and at propane concentration levels (0, 5, 50, 100, 200, 300, 400, and 500 ppm. ESA values were calculated for each sample. It was found that the ESA increased with the increasing thickness of the films. The results demonstrated the importance of the achieving of a large effective surface area for improving gas sensing performance. SnO2 thin films deposited by spray chemical were chosen to study the ESA effect on gas sensing properties because their very rough surfaces were appropriate for this application.

  1. Effective Passivation of Large Area Black Silicon Solar Cells by SiO2/SiNx:H Stacks

    Directory of Open Access Journals (Sweden)

    Zengchao Zhao

    2014-01-01

    Full Text Available The performance of black silicon solar cells with various passivation films was characterized. Large area (156×156 mm2 black silicon was prepared by silver-nanoparticle-assisted etching on pyramidal silicon wafer. The conversion efficiency of black silicon solar cell without passivation is 13.8%. For the SiO2 and SiNx:H passivation, the conversion efficiency of black silicon solar cells increases to 16.1% and 16.5%, respectively. Compared to the single film of surface passivation of black silicon solar cells, the SiO2/SiNx:H stacks exhibit the highest efficiency of 17.1%. The investigation of internal quantum efficiency (IQE suggests that the SiO2/SiNx:H stacks films decrease the Auger recombination through reducing the surface doping concentration and surface state density of the Si/SiO2 interface, and SiNx:H layer suppresses the Shockley-Read-Hall (SRH recombination in the black silicon solar cell, which yields the best electrical performance of b-Si solar cells.

  2. Synthesis and characterization of large-area and continuous MoS2 atomic layers by RF magnetron sputtering.

    Science.gov (United States)

    Hussain, Sajjad; Shehzad, Muhammad Arslan; Vikraman, Dhanasekaran; Khan, Muhammad Farooq; Singh, Jai; Choi, Dong-Chul; Seo, Yongho; Eom, Jonghwa; Lee, Wan-Gyu; Jung, Jongwan

    2016-02-21

    In this article, we report layer-controlled, continuous and large-area molydenum sulfide (MoS2) growth onto a SiO2/Si substrate by RF sputtering combined with sulfurization. A two-step process was employed to synthesize MoS2 films. In the first step, an atomically thin MoO3 film was deposited by RF magnetron sputtering at 300 °C. Subsequently, the as-sputtered MoO3 film was further subjected to post-annealing and sulfurization processes at 650 °C for 1 hour. It was observed that the number of layers of MoS2 can be controlled by adjusting the sputtering time. The fabricated MoS2 transistors exhibited high mobility values of ∼21 cm(2) V(-1) s(-1) (bilayer) and ∼25 cm(2) V(-1) s(-1) (trilayer), on/off ratios in the range of ∼10(7) (bilayer) and 10(4)-10(5) (trilayer), respectively. We believe that our proposed paradigm can start a new method for the growth of MoS2 in future electronics and optoelectronics applications.

  3. Large anisotropic normal-state magnetoresistance in clean MgB2 thin films.

    Science.gov (United States)

    Li, Qi; Liu, B T; Hu, Y F; Chen, J; Gao, H; Shan, L; Wen, H H; Pogrebnyakov, A V; Redwing, J M; Xi, X X

    2006-04-28

    We report a large normal-state magnetoresistance with temperature-dependent anisotropy in very clean epitaxial MgB2 thin films (residual resistivity much smaller than 1 microOmega cm) grown by hybrid physical-chemical vapor deposition. The magnetoresistance shows a complex dependence on the orientation of the applied magnetic field, with a large magnetoresistance (Delta(rho)/(rho)0=136%) observed for the field H perpendicular ab plane. The angular dependence changes dramatically as the temperature is increased, and at high temperatures the magnetoresistance maximum changes to H||ab. We attribute the large magnetoresistance and the evolution of its angular dependence with temperature to the multiple bands with different Fermi surface topology in MgB2 and the relative scattering rates of the sigma and pi bands, which vary with temperature due to stronger electron-phonon coupling for the sigma bands.

  4. Laser Direct Write micro-fabrication of large area electronics on flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zacharatos, F.; Makrygianni, M. [National Technical University of Athens, Physics Department, Zografou Campus, 15780 (Greece); Geremia, R.; Biver, E.; Karnakis, D. [Oxford Lasers Ltd, Unit 8 Moorbrook Park, Oxfordshire OX11 7HP (United Kingdom); Leyder, S.; Puerto, D.; Delaporte, P. [Aix-Marseille University, CNRS, LP3 – UMR 7341, 13288 Marseille Cedex 9 (France); Zergioti, I., E-mail: zergioti@central.ntua.gr [National Technical University of Athens, Physics Department, Zografou Campus, 15780 (Greece)

    2016-06-30

    Highlights: • Laser Direct Writing of metallic patterns with a minimum feature size of 1 μm. • Selective Laser Ablation of 50 nm thick metal films on flexible substrates. • Selective Laser sintering resulting in an electrical resistivity of 9 μΩ cm. • Laser fabrication of interdigitated electrodes for sensor applications. - Abstract: To date, Laser Direct Write (LDW) techniques, such as Laser Induced Forward Transfer (LIFT), selective laser ablation and selective laser sintering of metal nanoparticle (NP) ink layers are receiving growing attention for the printing of uniform and well-defined conductive patterns with resolution down to 10 μm. For flexible substrates in particular, selective laser sintering of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with large area electronics. In this work, LDW of silver NP inks has been carried out on polyethylene-terephthalate (PET), polyethylene-naphthalate (PEN) and polyimide (PI) substrates to achieve low electrical resistivity electrodes. In more detail, high speed short pulsed (picosecond and nanosecond) lasers with repetition rates up to 1 MHz were used to print (LIFT) metal NP inks. We thus achieved uniform and continuous patterns with a minimum feature size of 1 μm and a total footprint larger than 1 cm{sup 2}. Next, the printed patterns were laser sintered with ns pulses at 532 nm over a wide laser fluence window, resulting in an electrical resistivity of 10 μΩ cm. We carried out spatial beam shaping experiments to achieve a top-hat laser intensity profile and employed selective laser ablation of thin films (thickness on the order of 100 nm) to produce silver micro-electrodes with a resolution on the order of 10 μm and a low line edge roughness. Laser sintering was combined with laser ablation to constitute a fully autonomous micro-patterning technique of metallic micro-features, with a 10 μm resolution and geometrical characteristics tuned for

  5. Structural-electromagnetic bidirectional coupling analysis of space large film reflector antennas

    Science.gov (United States)

    Zhang, Xinghua; Zhang, Shuxin; Cheng, ZhengAi; Duan, Baoyan; Yang, Chen; Li, Meng; Hou, Xinbin; Li, Xun

    2017-10-01

    As used for energy transmission, a space large film reflector antenna (SLFRA) is characterized by large size and enduring high power density. The structural flexibility and the microwave radiation pressure (MRP) will lead to the phenomenon of structural-electromagnetic bidirectional coupling (SEBC). In this paper, the SEBC model of SLFRA is presented, then the deformation induced by the MRP and the corresponding far field pattern deterioration are simulated. Results show that, the direction of the MRP is identical to the normal of the reflector surface, and the magnitude is proportional to the power density and the square of cosine incident angle. For a typical cosine function distributed electric field, the MRP is a square of cosine distributed across the diameter. The maximum deflections of SLFRA linearly increase with the increasing microwave power densities and the square of the reflector diameters, and vary inversely with the film thicknesses. When the reflector diameter becomes 100 m large and the microwave power density exceeds 102 W/cm2, the gain loss of the 6.3 μm-thick reflector goes beyond 0.75 dB. When the MRP-induced deflection degrades the reflector performance, the SEBC should be taken into account.

  6. Large Eddy Simulation of the Effects of Plasma Actuation Strength on Film Cooling Efficiency

    Science.gov (United States)

    Li, Guozhan; Chen, Fu; Li, Linxi; Song, Yanping

    2016-11-01

    In this article, numerical investigation of the effects of different plasma actuation strengths on the film cooling flow characteristics has been conducted using large eddy simulation (LES). For this numerical research, the plasma actuator is placed downstream of the trailing edge of the film cooling hole and a phenomenological model is employed to provide the electric field generated by it, resulting in the body forces. Our results show that as the plasma actuation strength grows larger, under the downward effect of the plasma actuation, the jet trajectory near the cooling hole stays closer to the wall and the recirculation region observably reduces in size. Meanwhile, the momentum injection effect of the plasma actuation also actively alters the distributions of the velocity components downstream of the cooling hole. Consequently, the influence of the plasma actuation strength on the Reynolds stress downstream of the cooling hole is remarkable. Furthermore, the plasma actuation weakens the strength of the kidney shaped vortex and prevents the jet from lifting off the wall. Therefore, with the increase of the strength of the plasma actuation, the coolant core stays closer to the wall and tends to split into two distinct regions. So the centerline film cooling efficiency is enhanced, and it is increased by 55% at most when the plasma actuation strength is 10.

  7. Analysis of light intensity dependence of organic photovoltaics: towards efficient large-area solar cells

    NARCIS (Netherlands)

    Galagan, Y.O.; Manor, A.; Andriessen, H.A.J.M.; Katz, E.A.

    2012-01-01

    Large-area organic solar cells are known to suffer from a major efficiency decrease which originates from the combination of a voltage drop across the front electrode and the voltage-dependent photocurrent. In this letter, we demonstrate this efficiency loss on large area, indium tin oxide free cell

  8. Microscopic evaluation of the absolute fluence distribution of a large-area uniform ion beam using the track-etching technique

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, Akane, E-mail: ogawa.akane@jaea.go.jp [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Yamaki, Tetsuya [High Performance Polymer Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Yuri, Yosuke [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Sawada, Shin-ichi [High Performance Polymer Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Yuyama, Takahiro [Department of Advanced Radiation Technology, Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)

    2013-11-01

    The absolute fluence distribution of a large-area uniform beam was investigated microscopically via track etching of an Ar-irradiated polyethylene terephthalate (PET) film. The irradiated sample was divided equally into 64 pieces, for each of which the track-pore densities were counted over a 12 × 17 μm{sup 2} microscopic area near the center. For comparison, the relative intensity distribution was obtained by measuring the optical density of a similarly irradiated Gafchromic film at a resolution of 500 × 500 μm{sup 2} and then taking the measured value at the center of each of the 64 areas. The relative standard deviations of the distributions were in good agreement despite the difference in the observed resolution area and the small sample number. It was, therefore, confirmed that track etching is a reliable technique for evaluating absolute fluence and that a uniform intensity distribution of the beam was microscopically realized.

  9. Selected area chemical vapor deposition of thin films for conductometric microelectronic chemical sensors

    Science.gov (United States)

    Majoo, Sanjeev

    Recent advances in microelectronics and silicon processing have been exploited to fabricate miniaturized chemical sensors. Although the capability of chemical sensing technology has grown steadily, it has been outpaced by the increasing demands for more reliable, inexpensive, and selective sensors. The diversity of applications requires the deployment of different sensing materials that have rich interfacial chemistry. However, several promising sensor materials are often incompatible with silicon micromachining and their deposition requires complicated masking steps. The new approach described here is to first micromachine a generic, instrumented, conductometric, microelectronic sensor platform that is fully functional except for the front-end sensing element. This generic platform contains a thin dielectric membrane, an integrated boron-doped silicon heater, and conductance electrodes. The membrane has low thermal mass and excellent thermal isolation. A proprietary selected-area chemical vapor deposition (SACVD) process in a cold-wall reactor at low pressures was then used to achieve maskless, self-lithographic deposition of thin films. The temperature-programmable integrated microheater initiates localized thermal decomposition/reaction of suitable CVD precursors confined to a small heated area (500 mum in diameter), and this creates the active sensing element. Platinum and titania (TiOsb2) films were deposited from pyrolysis of organometallic precursors, tetrakistrifluorophosphine platinum Pt(PFsb3)sb4 and titanium tetraisopropoxide Ti(OCH(CHsb3)sb2rbrack sb4, respectively. Deposition of gold metal films from chlorotriethylphosphine gold (Csb2Hsb5)sb3PAuCl precursor was also attempted but without success. The conductance electrodes permit in situ monitoring of film growth. The as-deposited films were characterized in situ by conductance measurements and optical microscopy and ex situ by electron microscopy and spectroscopy methods. Devices equipped with

  10. Laser Direct Write micro-fabrication of large area electronics on flexible substrates

    Science.gov (United States)

    Zacharatos, F.; Makrygianni, M.; Geremia, R.; Biver, E.; Karnakis, D.; Leyder, S.; Puerto, D.; Delaporte, P.; Zergioti, I.

    2016-06-01

    To date, Laser Direct Write (LDW) techniques, such as Laser Induced Forward Transfer (LIFT), selective laser ablation and selective laser sintering of metal nanoparticle (NP) ink layers are receiving growing attention for the printing of uniform and well-defined conductive patterns with resolution down to 10 μm. For flexible substrates in particular, selective laser sintering of such NP patterns has been widely applied, as a low temperature and high resolution process compatible with large area electronics. In this work, LDW of silver NP inks has been carried out on polyethylene-terephthalate (PET), polyethylene-naphthalate (PEN) and polyimide (PI) substrates to achieve low electrical resistivity electrodes. In more detail, high speed short pulsed (picosecond and nanosecond) lasers with repetition rates up to 1 MHz were used to print (LIFT) metal NP inks. We thus achieved uniform and continuous patterns with a minimum feature size of 1 μm and a total footprint larger than 1 cm2. Next, the printed patterns were laser sintered with ns pulses at 532 nm over a wide laser fluence window, resulting in an electrical resistivity of 10 μΩ cm. We carried out spatial beam shaping experiments to achieve a top-hat laser intensity profile and employed selective laser ablation of thin films (thickness on the order of 100 nm) to produce silver micro-electrodes with a resolution on the order of 10 μm and a low line edge roughness. Laser sintering was combined with laser ablation to constitute a fully autonomous micro-patterning technique of metallic micro-features, with a 10 μm resolution and geometrical characteristics tuned for interdigitated electrodes for sensor applications.

  11. Fabrication of large area gratings with sub-micron pitch using mold micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, J.G.; Barron, C.C.; Stallard, B.; Kaushik, S.

    1997-03-01

    In this work, the authors have applied mold micromachining and standard photolithographic techniques to the fabrication of parts integrated with 0.4 micron pitch diffraction gratings. In principle, the approach should be scaleable to considerably finer pitches. They have achieved this by relying on the thickness of deposited or grown films, instead of photolithography, to determine the grating pitch. The gratings can be made to extend over large areas and the entire process is compatible with batch processing. Literally thousands of parts can be batch fabricated from a single lot of six inch wafers. In the first stage of the process they fabricate a planarized silicon dioxide pad over which the silicon nitride wave guide runs. The grating is formed by first patterning and etching single crystalline silicon to form a series of trenches with well defined pitch. The silicon bounding the trenches is then thinned by thermal oxidation followed by stripping of the silicon dioxide. The trenches are filled by a combination of polysilicon depositions and thermal oxidations. Chemical mechanical polishing (CMP) is used to polish back these structures resulting in a series of alternating 2000 {angstrom} wide lines of silicon and silicon dioxide. The thickness of the lines is determined by the oxidation time and the polysilicon deposition thickness. The silicon lines are selectively recessed by anisotropic reactive ion etching, thus forming the mold for the grating. The mold is filled with low stress silicon nitride deposited by chemical vapor deposition. A wave guide is then patterned into the silicon nitride and the mold is locally removed by a combination of deep silicon trench etching and wet KOH etching. This results in a suspended diffraction grating/membrane over the KOH generated pit.

  12. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    Directory of Open Access Journals (Sweden)

    Yann-Cherng Chern

    2015-08-01

    Full Text Available A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  13. Highly Flexible and High-Performance Complementary Inverters of Large-Area Transition Metal Dichalcogenide Monolayers

    KAUST Repository

    Pu, Jiang

    2016-03-23

    Complementary inverters constructed from large-area monolayers of WSe2 and MoS2 achieve excellent logic swings and yield an extremely high gain, large total noise margin, low power consumption, and good switching speed. Moreover, the WSe2 complementary-like inverters built on plastic substrates exhibit high mechanical stability. The results provide a path toward large-area flexible electronics. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Surface-area-controlled synthesis of porous TiO2 thin films for gas-sensing applications

    Science.gov (United States)

    Park, Jae Young; Kim, Ho-hyoung; Rana, Dolly; Jamwal, Deepika; Katoch, Akash

    2017-03-01

    Surface-area-controlled porous TiO2 thin films were prepared via a simple sol–gel chemical route, and their gas-sensing properties were thoroughly investigated in the presence of typical oxidizing NO2 gas. The surface area of TiO2 thin films was controlled by developing porous TiO2 networked by means of controlling the TiO2-to-TTIP (titanium isopropoxide, C12H28O4Ti) molar ratio, where TiO2 nanoparticles of size ∼20 nm were used. The sensor’s response was found to depend on the surface area of the TiO2 thin films. The porous TiO2 thin-film sensor with greater surface area was more sensitive than those of TiO2 thin films with lesser surface area. The improved sensing ability was ascribed to the porous network formed within the thin films by TiO2 sol. Our results show that surface area is a key parameter for obtaining superior gas-sensing performance; this provides important guidelines for preparing and using porous thin films for gas-sensing applications.

  15. Surface-area-controlled synthesis of porous TiO2 thin films for gas-sensing applications.

    Science.gov (United States)

    Park, Jae Young; Kim, Ho-Hyoung; Rana, Dolly; Jamwal, Deepika; Katoch, Akash

    2017-03-03

    Surface-area-controlled porous TiO2 thin films were prepared via a simple sol-gel chemical route, and their gas-sensing properties were thoroughly investigated in the presence of typical oxidizing NO2 gas. The surface area of TiO2 thin films was controlled by developing porous TiO2 networked by means of controlling the TiO2-to-TTIP (titanium isopropoxide, C12H28O4Ti) molar ratio, where TiO2 nanoparticles of size ∼20 nm were used. The sensor's response was found to depend on the surface area of the TiO2 thin films. The porous TiO2 thin-film sensor with greater surface area was more sensitive than those of TiO2 thin films with lesser surface area. The improved sensing ability was ascribed to the porous network formed within the thin films by TiO2 sol. Our results show that surface area is a key parameter for obtaining superior gas-sensing performance; this provides important guidelines for preparing and using porous thin films for gas-sensing applications.

  16. Large Area 2D and 3D Colloidal Photonic Crystals Fabricated by a Roll-to-Roll Langmuir-Blodgett Method.

    Science.gov (United States)

    Parchine, Mikhail; McGrath, Joe; Bardosova, Maria; Pemble, Martyn E

    2016-06-14

    We present our results on the fabrication of large area colloidal photonic crystals on flexible poly(ethylene terephthalate) (PET) film using a roll-to-roll Langmuir-Blodgett technique. Two-dimensional (2D) and three-dimensional (3D) colloidal photonic crystals from silica nanospheres (250 and 550 nm diameter) with a total area of up to 340 cm(2) have been fabricated in a continuous manner compatible with high volume manufacturing. In addition, the antireflective properties and structural integrity of the films have been enhanced via the use of a second roll-to-roll process, employing a slot-die coating of an optical adhesive over the photonic crystal films. Scanning electron microscopy images, atomic force microscopy images, and UV-vis optical transmission and reflection spectra of the fabricated photonic crystals are analyzed. This analysis confirms the high quality of the 2D and 3D photonic crystals fabricated by the roll-to-roll LB technique. Potential device applications of the large area 2D and 3D colloidal photonic crystals on flexible PET film are briefly reviewed.

  17. Large gain for crystalline thin films of thiophene/phenylene co-oligomer by photopumping with femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Hiroyuki, E-mail: h-mochizuki@aist.go.jp [Electronics and Photonics Research Institutes, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Kawaguchi, Yoshizo; Sasaki, Fumio [Electronics and Photonics Research Institutes, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Hotta, Shu [Department of Macromolecular Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585 (Japan)

    2014-11-15

    We have evaluated the emission behaviors of crystalline thin films of thiophene/phenylene co-oligomers. Crystalline films of 2,5-bis(4-biphenylyl)thiophene (BP1T) were prepared on a substrate by vapor deposition followed by thermal treatment. The BP1T films contained crystalline domains several hundred micrometers in size. We examined the emission behavior of crystalline BP1T thin films by femtosecond laser excitation. Very high gains of over 500 cm{sup −1} were obtained for the crystalline BP1T film. Furthermore, the emission cross section of the crystalline BP1T film was on the order of 10{sup –16} cm{sup 2}, rivaling that of dilute solutions of organic laser dyes. - Highlights: • Vapor deposition and thermal treatment is effective for preparation of crystallized film. • Femtosecond laser is efficient for excitation of photo-active materials. • Very large gain values over 500 cm{sup −1} for BP1T crystallized films. • Emission cross section of 10{sup −16} cm{sup 2} in crystallized film.

  18. Rosin-enabled ultraclean and damage-free transfer of graphene for large-area flexible organic light-emitting diodes

    Science.gov (United States)

    Zhang, Zhikun; Du, Jinhong; Zhang, Dingdong; Sun, Hengda; Yin, Lichang; Ma, Laipeng; Chen, Jiangshan; Ma, Dongge; Cheng, Hui-Ming; Ren, Wencai

    2017-02-01

    The large polymer particle residue generated during the transfer process of graphene grown by chemical vapour deposition is a critical issue that limits its use in large-area thin-film devices such as organic light-emitting diodes. The available lighting areas of the graphene-based organic light-emitting diodes reported so far are usually organic light-emitting diode with a high brightness of about 10,000 cd m-2 that can already satisfy the requirements for lighting sources and displays.

  19. Reactive sputtering of TiN films at large substrate to target distances

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J.; Kadlec, S. (Czechosovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics)

    1990-01-01

    This paper is a critical review of the present status of the magnetron ion sputter plating of thin CiN films. Thus different possibilities of extracting high ion currents 1{sub s} from the magnetron discharge to substrates located not only at standard target to substrate distances d{sub S-T} of about 50 mm but also at larger distances d{sub S-T} are discussed in detail. Special attention is devoted to magnetron sputtering systems with enhanced ionization, to plasma confinement in the magnetron sputtering systems and to the discharge characteristics of an unbalanced magnetron (UM). It is shown that a UM can be operated in the regime of a double-site-sustained discharge (DSSD) and in this case large 1{sub s} can be extracted to substrates located in large D{sub S-T} of about 200 mm and even at high pressures p = 5 Pa. A physical comparison of the conventional magnetron (CM), UM and DSSD is also given. Considerable attention is also devoted to the effect of ion bombardment on properties of TiN films created in the sputtering system using DSSD. (author).

  20. Generation of uniform large-area very high frequency plasmas by launching two specific standing waves simultaneously

    Science.gov (United States)

    Chen, Hsin-Liang; Tu, Yen-Cheng; Hsieh, Cheng-Chang; Lin, Deng-Lain; Leou, Keh-Chyang

    2014-09-01

    With the characteristics of higher electron density and lower ion bombardment energy, large-area VHF (very high frequency) plasma enhanced chemical vapor deposition has become an essential manufacturing equipment to improve the production throughput and efficiency of thin film silicon solar cell. However, the combination of high frequency and large electrodes leads to the so-called standing wave effect causing a serious problem for the deposition uniformity of silicon thin film. In order to address this issue, a technique based on the idea of simultaneously launching two standing waves that possess similar amplitudes and are out of phase by 90° in time and space is proposed in this study. A linear plasma reactor with discharge length of 54 cm is tested with two different frequencies including 60 and 80 MHz. The experimental results show that the proposed technique could effectively improve the non-uniformity of VHF plasmas from >±60% when only one standing wave is applied to reactor configuration adopted in this study, in which the standing wave effect along the much shorter dimension can be ignored, the proposed technique is applicable to different frequencies without the need to alter the number and arrangement of power feeding points.

  1. Generation of uniform large-area very high frequency plasmas by launching two specific standing waves simultaneously

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hsin-Liang, E-mail: hlchen@iner.gov.tw; Tu, Yen-Cheng; Hsieh, Cheng-Chang; Lin, Deng-Lain [Physics Division, Institute of Nuclear Energy Research (INER), Longtan, Taoyuan County 32546, Taiwan (China); Leou, Keh-Chyang [Department of Engineering and System Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

    2014-09-14

    With the characteristics of higher electron density and lower ion bombardment energy, large-area VHF (very high frequency) plasma enhanced chemical vapor deposition has become an essential manufacturing equipment to improve the production throughput and efficiency of thin film silicon solar cell. However, the combination of high frequency and large electrodes leads to the so-called standing wave effect causing a serious problem for the deposition uniformity of silicon thin film. In order to address this issue, a technique based on the idea of simultaneously launching two standing waves that possess similar amplitudes and are out of phase by 90° in time and space is proposed in this study. A linear plasma reactor with discharge length of 54 cm is tested with two different frequencies including 60 and 80 MHz. The experimental results show that the proposed technique could effectively improve the non-uniformity of VHF plasmas from >±60% when only one standing wave is applied to <±10% once two specific standing waves are launched at the same time. Moreover, in terms of the reactor configuration adopted in this study, in which the standing wave effect along the much shorter dimension can be ignored, the proposed technique is applicable to different frequencies without the need to alter the number and arrangement of power feeding points.

  2. Large eddy simulations of turbulent flows on graphics processing units: Application to film-cooling flows

    Science.gov (United States)

    Shinn, Aaron F.

    Computational Fluid Dynamics (CFD) simulations can be very computationally expensive, especially for Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS) of turbulent ows. In LES the large, energy containing eddies are resolved by the computational mesh, but the smaller (sub-grid) scales are modeled. In DNS, all scales of turbulence are resolved, including the smallest dissipative (Kolmogorov) scales. Clusters of CPUs have been the standard approach for such simulations, but an emerging approach is the use of Graphics Processing Units (GPUs), which deliver impressive computing performance compared to CPUs. Recently there has been great interest in the scientific computing community to use GPUs for general-purpose computation (such as the numerical solution of PDEs) rather than graphics rendering. To explore the use of GPUs for CFD simulations, an incompressible Navier-Stokes solver was developed for a GPU. This solver is capable of simulating unsteady laminar flows or performing a LES or DNS of turbulent ows. The Navier-Stokes equations are solved via a fractional-step method and are spatially discretized using the finite volume method on a Cartesian mesh. An immersed boundary method based on a ghost cell treatment was developed to handle flow past complex geometries. The implementation of these numerical methods had to suit the architecture of the GPU, which is designed for massive multithreading. The details of this implementation will be described, along with strategies for performance optimization. Validation of the GPU-based solver was performed for fundamental bench-mark problems, and a performance assessment indicated that the solver was over an order-of-magnitude faster compared to a CPU. The GPU-based Navier-Stokes solver was used to study film-cooling flows via Large Eddy Simulation. In modern gas turbine engines, the film-cooling method is used to protect turbine blades from hot combustion gases. Therefore, understanding the physics of

  3. Large magnetization and high Curie temperature in highly disordered nanoscale Fe2CrAl thin films

    Science.gov (United States)

    Dulal, Rajendra P.; Dahal, Bishnu R.; Forbes, Andrew; Pegg, Ian L.; Philip, John

    2017-02-01

    We have successfully grown nanoscale Fe2CrAl thin films on polished Si/SiO2 substrates using an ultra-high vacuum deposition with a base pressure of 9×10-10 Torr. The thickness of thin films ranges from 30 to 100 nm. These films exhibit cubic crystal structure with lattice disorder and display ferromagnetic behavior. The Curie temperature is greater than 400 K, which is much higher than that reported for bulk Fe2CrAl. The magnetic moments of the films varies from 2.5 to 2.8 μB per formula unit, which is larger than the reported bulk values. Thus, the disordered nanoscale Fe2CrAl films exhibit strong Fe-Fe exchange interactions through Fe-Cr-Fe and Fe-Al-Fe layers, resulting in both a large magnetization and a high Curie temperature.

  4. Large format cylindrical lens films formed by roll-to-roll ultraviolet embossing and applications as diffusion films

    Science.gov (United States)

    Shan, X. C.; Liu, T.; Mohaime, M.; Salam, B.; Liu, Y. C.

    2015-03-01

    A roll-to-roll (R2R) ultraviolet (UV) embossing system has been developed for manufacturing micro features on continuous flexible films. The R2R UV embossing system, which has an embossing roller of 160 mm in diameter, can handle flexible polymer films with a width up to 500 mm and thickness ranging from 0.05 to 0.5 mm. A metal sheet template with micro features on its surface is mounted to the embossing roller and used as embossing mould. A slot die coating unit that has a coating width of 250 mm is used to deposit liquid UV curable resin on polymer films and coating thickness ranging from 10 to 50 µm has been achieved. Continuous roll-to-roll UV embossing is conducted and optical films with cylindrical lens arrays (curvature radius = 112  ±  2 µm, sag height = 28  ±  0.5 µm and pitch = 150  ±  2 µm) are formed. The optical films are used for diffusion to improve light uniformity of a printed lighting film that consists of lighting stripes and dark blank lines. The evaluation results show that the non-uniformity of light intensity can be reduced from 30% (with only lighting panel) to about 3% with the cylindrical lens films.

  5. Large area substrate for surface enhanced Raman spectroscopy (SERS) using glass-drawing technique

    Science.gov (United States)

    Ivanov, Ilia N.; Simpson, John T.

    2012-06-26

    A method of making a large area substrate comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes. Each cut drawn tube has a first end and a second end along the longitudinal direction of the respective cut drawn tube. The cut drawn tubes collectively have a predetermined periodicity. The method of making a large area substrate also comprises forming a metal layer on the first ends of the cut drawn tubes to provide a large area substrate.

  6. Characterization of the VEGA ASIC coupled to large area position-sensitive Silicon Drift Detectors

    CERN Document Server

    Campana, R; Fuschino, F; Ahangarianabhari, M; Macera, D; Bertuccio, G; Grassi, M; Labanti, C; Marisaldi, M; Malcovati, P; Rachevski, A; Zampa, G; Zampa, N; Andreani, L; Baldazzi, G; Del Monte, E; Favre, Y; Feroci, M; Muleri, F; Rashevskaya, I; Vacchi, A; Ficorella, F; Giacomini, G; Picciotto, A; Zuffa, M

    2014-01-01

    Low-noise, position-sensitive Silicon Drift Detectors (SDDs) are particularly useful for experiments in which a good energy resolution combined with a large sensitive area is required, as in the case of X-ray astronomy space missions and medical applications. This paper presents the experimental characterization of VEGA, a custom Application Specific Integrated Circuit (ASIC) used as the front-end electronics for XDXL-2, a large-area (30.5 cm^2) SDD prototype. The ASICs were integrated on a specifically developed PCB hosting also the detector. Results on the ASIC noise performances, both stand-alone and bonded to the large area SDD, are presented and discussed.

  7. Semiconductor/dielectric half-coaxial nanowire arrays for large-area nanostructured photovoltaics

    Science.gov (United States)

    Hua, X.; Zeng, Y.; Shen, W. Z.

    2014-03-01

    We present a simple assembly strategy of single nanowires (NWs) to form half-coaxial nanowire arrays (NWAs) which can be easily realized in large size by standard pattering and deposition techniques. Through the finite-difference time-domain simulation, we show that the proposed half-coaxial NWAs effectively preserve the leaky modes resonances within single NWs and consequently achieve strong absorption enhancement under optimization of various structural factors. The best half-coaxial NWAs with 100 nm thick absorbing shell offer equivalent light absorption of more than 400 nm thick planar film. Benefiting from the >75% cut of the required thickness of the absorbing layer, the performances of the demonstrated half-coaxial NWAs based a-Si thin film solar cell also gain significant improvement.

  8. Large-area growth of multi-layer hexagonal boron nitride on polished cobalt foils by plasma-assisted molecular beam epitaxy

    Science.gov (United States)

    Xu, Zhongguang; Tian, Hao; Khanaki, Alireza; Zheng, Renjing; Suja, Mohammad; Liu, Jianlin

    2017-01-01

    Two-dimensional (2D) hexagonal boron nitride (h-BN), which has a similar honeycomb lattice structure to graphene, is promising as a dielectric material for a wide variety of potential applications based on 2D materials. Synthesis of high-quality, large-size and single-crystalline h-BN domains is of vital importance for fundamental research as well as practical applications. In this work, we report the growth of h-BN films on mechanically polished cobalt (Co) foils using plasma-assisted molecular beam epitaxy. Under appropriate growth conditions, the coverage of h-BN layers can be readily controlled by growth time. A large-area, multi-layer h-BN film with a thickness of 5~6 nm is confirmed by Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. In addition, the size of h-BN single domains is 20~100 μm. Dielectric property of as-grown h-BN film is evaluated by characterization of Co(foil)/h-BN/Co(contact) capacitor devices. Breakdown electric field is in the range of 3.0~3.3 MV/cm, which indicates that the epitaxial h-BN film has good insulating characteristics. In addition, the effect of substrate morphology on h-BN growth is discussed regarding different domain density, lateral size, and thickness of the h-BN films grown on unpolished and polished Co foils. PMID:28230178

  9. A dilute Cu(Ni) alloy for synthesis of large-area Bernal stacked bilayer graphene using atmospheric pressure chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Madito, M. J.; Bello, A.; Dangbegnon, J. K.; Momodu, D. Y.; Masikhwa, T. M.; Barzegar, F.; Manyala, N., E-mail: ncholu.manyala@up.ac.za [Department of Physics, Institute of Applied Materials, SARCHI Chair in Carbon Technology and Materials, University of Pretoria, Pretoria 0028 (South Africa); Oliphant, C. J.; Jordaan, W. A. [National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040 (South Africa); Fabiane, M. [Department of Physics, Institute of Applied Materials, SARCHI Chair in Carbon Technology and Materials, University of Pretoria, Pretoria 0028 (South Africa); Department of Physics, National University of Lesotho, P.O. Roma 180 (Lesotho)

    2016-01-07

    A bilayer graphene film obtained on copper (Cu) foil is known to have a significant fraction of non-Bernal (AB) stacking and on copper/nickel (Cu/Ni) thin films is known to grow over a large-area with AB stacking. In this study, annealed Cu foils for graphene growth were doped with small concentrations of Ni to obtain dilute Cu(Ni) alloys in which the hydrocarbon decomposition rate of Cu will be enhanced by Ni during synthesis of large-area AB-stacked bilayer graphene using atmospheric pressure chemical vapour deposition. The Ni doped concentration and the Ni homogeneous distribution in Cu foil were confirmed with inductively coupled plasma optical emission spectrometry and proton-induced X-ray emission. An electron backscatter diffraction map showed that Cu foils have a single (001) surface orientation which leads to a uniform growth rate on Cu surface in early stages of graphene growth and also leads to a uniform Ni surface concentration distribution through segregation kinetics. The increase in Ni surface concentration in foils was investigated with time-of-flight secondary ion mass spectrometry. The quality of graphene, the number of graphene layers, and the layers stacking order in synthesized bilayer graphene films were confirmed by Raman and electron diffraction measurements. A four point probe station was used to measure the sheet resistance of graphene films. As compared to Cu foil, the prepared dilute Cu(Ni) alloy demonstrated the good capability of growing large-area AB-stacked bilayer graphene film by increasing Ni content in Cu surface layer.

  10. A novel photovoltaic power system which uses a large area concentrator mirror

    Science.gov (United States)

    Arrison, Anne; Fatemi, Navid

    1987-01-01

    A preliminary analysis has been made of a novel photovoltaic power system concept. The system is composed of a small area, dense photovoltaic array, a large area solar concentrator, and a battery system for energy storage. The feasibility of such a system is assessed for space power applications. The orbital efficiency, specific power, mass, and area of the system are calculated under various conditions and compared with those for the organic Rankine cycle solar dynamic system proposed for Space Station. Near term and advanced large area concentrator photovoltaic systems not only compare favorably to solar dynamic systems in terms of performance but offer other benefits as well.

  11. Synthesis and Characterization of Large Surface Area Yttrium Oxide by Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    崔大立; 龙志奇; 张顺利; 崔梅生; 黄小卫

    2004-01-01

    The method for preparing yttrium oxide with large specific surface area was introduced. By means of BET, SEM, TG and DTA analysis, the effects of precipitant, stirring velocity, non-RE impurity in solution, calcination temperature, on the surface area were studied respectively. The Y2O3 sample with specific surface area of more than 60 m2*g-1 and L.O.I less than 1% was prepared in the suitable precipitation condition and calcinations temperature when the ammonia used as precipitant. The SEM shows that the Y2O3 prepared with large surface area is the aggregation of about 50 nm particles.

  12. Thermal Stability of Magnetic States in Circular Thin-Film Nanomagnets with Large Perpendicular Magnetic Anisotropy

    Science.gov (United States)

    Chaves-O'Flynn, Gabriel

    The scaling of the energy barrier to magnetization reversal in thin-film nanomagnets with perpendicular magnetization as a function of their lateral size is of great interest and importance for high-density magnetic random access memory devices. Experimental studies of such elements show either a quadratic or linear dependence of the energy barrier on element diameter. I will discuss a theoretical model we developed to determine the micromagnetic configurations that set the energy barrier for thermally activated reversal of a thin disk with perpendicular magnetic anisotropy as a function of disk diameter. We find a critical length in the problem that is set by the exchange and effective perpendicular magnetic anisotropy energies, with the latter including the size dependence of the demagnetization energy. For diameters smaller than this critical length, the reversal occurs by nearly coherent magnetization rotation and the energy barrier scales with the square of the diameter normalized to the critical length (for fixed film thickness), while for larger diameters, the transition state has a domain wall, and the energy barrier depends linearly on the normalized diameter. Simple analytic expressions are derived for these two limiting cases and verified using full micromagnetic simulations with the string method. Further, the effect of an applied field is considered and shown to lead to a plateau in the energy barrier versus diameter dependence at large diameters. Based on these finding I discuss the prospects and material challenges in the scaling of magnetic memory devices based on thin films with strong perpendicular magnetic anisotropy. In collaboration with G. Wolf, J. Z. Sun and A. D. Kent. Supported by NSF-DMR-1309202 and in part by Spin Transfer Technologies Inc. and the Nanoelectronics Research Initiative through the Institute for Nanoelectronics Discovery and Exploration.

  13. Production of the Large-area Plastic Scintillator for Beta-ray Detection using Epoxy Resin

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jong Soo; Choi, Yong Seok; Hong, Sang Bum; Seo, Bum Kyung; Moon, Jei Kwon; Choi, Jong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this study, we prepared a plastic scintillator whose manufacturing process is simple and can be freely shaped. A thin plate of the plastic scintillator was manufactured using epoxy resin as a polymer. The plastic scintillator was made by mixing epoxy resin and organic scintillators under various conditions. The optimal mixture ratio to prepare the plastic scintillator was derived from the above results. Using the derived results, we made the large-area plastic scintillator which can quickly measure the contamination site and evaluated characteristics of the large-area plastic scintillator in the laboratory. A thin plate of a plastic scintillator with a simple preparation process can be freely shaped using epoxy resin and organic scintillators such as PPO and POPOP. PPO emits scintillation of light in the ultraviolet range, and POPOP is a wave shifter for moving the wavelength responsible for the PMT. The mixture ratio of PPO and POPOP was determined using their emission spectra. The optimal weight percentage of PPO and POPOP in an organic scintillator was determined to be 0.2 wt%:0.01 wt%. Based on the above results, the large-area plastic scintillator of the window size of a typical pancake-type αβ surface contamination counter was prepared. We want to evaluate the characteristics of the large-area plastic scintillator. However, there were the difficulties in evaluating characteristics of the large-area plastic scintillator. The cross-sectional area of the large-area plastic scintillator is significantly different to PMT.

  14. Novel Large Area High Resolution Neutron Detector for the Spallation Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Lacy, Jeffrey L

    2009-05-22

    Neutron scattering is a powerful technique that is critically important for materials science and structural biology applications. The knowledge gained from past developments has resulted in far-reaching advances in engineering, pharmaceutical and biotechnology industries, to name a few. New facilities for neutron generation at much higher flux, such as the SNS at Oak Ridge, TN, will greatly enhance the capabilities of neutron scattering, with benefits that extend to many fields and include, for example, development of improved drug therapies and materials that are stronger, longer-lasting, and more impact-resistant. In order to fully realize this enhanced potential, however, higher neutron rates must be met with improved detection capabilities, particularly higher count rate capability in large size detectors, while maintaining practicality. We have developed a neutron detector with the technical and economic advantages to accomplish this goal. This new detector has a large sensitive area, offers 3D spatial resolution, high sensitivity and high count rate capability, and it is economical and practical to produce. The proposed detector technology is based on B-10 thin film conversion of neutrons in long straw-like gas detectors. A stack of many such detectors, each 1 meter in length, and 4 mm in diameter, has a stopping power that exceeds that of He-3 gas, contained at practical pressures within an area detector. With simple electronic readout methods, straw detector arrays can provide spatial resolution of 4 mm FWHM or better, and since an array detector of such form consists of several thousand individual elements per square meter, count rates in a 1 m^2 detector can reach 2?10^7 cps. Moreover, each individual event can be timetagged with a time resolution of less than 0.1 ?sec, allowing accurate identification of neutron energy by time of flight. Considering basic elemental cost, this novel neutron imaging detector can be commercially produced economically

  15. Large-roll growth of 25-inch hexagonal BN monolayer film for self-release buffer layer of free-standing GaN wafer

    Science.gov (United States)

    Wu, Chenping; Soomro, Abdul Majid; Sun, Feipeng; Wang, Huachun; Huang, Youyang; Wu, Jiejun; Liu, Chuan; Yang, Xiaodong; Gao, Na; Chen, Xiaohong; Kang, Junyong; Cai, Duanjun

    2016-01-01

    Hexagonal boron nitride (h-BN) is known as promising 2D material with a wide band-gap (~6 eV). However, the growth size of h-BN film is strongly limited by the size of reaction chamber. Here, we demonstrate the large-roll synthesis of monolayer and controllable sub-monolayer h-BN film on wound Cu foil by low pressure chemical vapor deposition (LPCVD) method. By winding the Cu foil substrate into mainspring shape supported by a multi-prong quartz fork, the reactor size limit could be overcome by extending the substrate area to a continuous 2D curl of plane inward. An extremely large-size monolayer h-BN film has been achieved over 25 inches in a 1.2” tube. The optical band gap of h-BN monolayer was determined to be 6.0 eV. The h-BN film was uniformly transferred onto 2” GaN or 4” Si wafer surfaces as a release buffer layer. By HVPE method, overgrowth of thick GaN wafer over 200 μm has been achieved free of residual strain, which could provide high quality homo-epitaxial substrate. PMID:27756906

  16. Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Tatsuya [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan)], E-mail: kiku@eng.hokudai.ac.jp; Sakairi, Masatoshi [Graduate School of Engineering, Hokkaido University, N13-W8, Kita-Ku, Sapporo 060-8628 (Japan); Takahashi, Hideaki [Asahikawa National College of Technology, Syunkohdai, 2-2, 1-6, Asahikawa 071-8142 (Japan)

    2009-11-30

    Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion. The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-{mu}m wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing.

  17. High-temperature large-gap quantum anomalous Hall insulating state in ultrathin double perovskite films

    Science.gov (United States)

    Baidya, Santu; Waghmare, Umesh V.; Paramekanti, Arun; Saha-Dasgupta, Tanusri

    2016-10-01

    Towards the goal of realizing topological phases in thin films of correlated oxide and heterostructures, we propose here a quantum anomalous Hall insulator (QAHI) in ultrathin films of double perovskites based on mixed 3 d -5 d or 3 d -4 d transition-metal ions, grown along the [111] direction. Considering the specific case of ultrathin Ba2FeReO6 , we present a theoretical analysis of an effective Hamiltonian derived from first principles. We establish that a strong spin-orbit coupling at the Re site, t2 g symmetry of the low-energy d bands, polarity of its [111] orientation of perovskite structure, and mixed 3 d -5 d chemistry results in room temperature magnetism with a robust QAHI state of Chern number C =1 and a large band gap. We uncover and highlight a nonrelativistic orbital Rashba-type effect in addition to the spin-orbit coupling, that governs this QAHI state. With a band gap of ˜100 meV in electronic structure and magnetic transition temperature Tc˜300 K estimated by Monte Carlo simulations, our finding of the QAHI state in ultrathin Ba2FeReO6 is expected to stimulate experimental verification along with possible practical applications of its dissipationless edge currents.

  18. The investigation of timing large area scintillation detectors with SiPM light sensors properties

    Science.gov (United States)

    Runtso, M. F.; Naumov, P. Yu; Naumov, P. P.; Maklyaev, E. F.; Kaplin, V. A.; Fomin, V. S.; Razzhivin, I. S.; Melikyan, Yu A.

    2017-01-01

    The timing large area plastic scintillation detectors with silicon photomultipliers as photosensors properties were investigated using a cosmic radiation at the ground level. Different techniques of the amplitude spectra and efficiency measurements were implemented. The measurements results are presented.

  19. EnviroAtlas - Percent Large, Medium, and Small Natural Areas for the Conterminous United States

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset contains the percentage of small, medium, and large natural areas for each Watershed Boundary Dataset (WBD) 12-Digit Hydrologic Unit Code...

  20. Intermodal parametric gain of degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    OpenAIRE

    Petersen, Sidsel Rübner; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2013-01-01

    Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process.

  1. Frequency conversion through spontaneous degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin;

    2014-01-01

    Frequency conversion through spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers. Different FWM processes are observed, phasematching between fiber modes of orthogonal polarization, intermodal phasematching across bandgaps, and intramodal...

  2. Large area crop inventory experiment crop assessment subsystem software requirements document

    Science.gov (United States)

    1975-01-01

    The functional data processing requirements are described for the Crop Assessment Subsystem of the Large Area Crop Inventory Experiment. These requirements are used as a guide for software development and implementation.

  3. Large-Area, UV-Optimized, Back-Illuminated Silicon Photomultiplier Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Large-area (3m2), UV-sensitive focal plane arrays are needed for observation of air showers from ultra-high energy cosmic rays (JEM-EUSO) as well as for...

  4. Accuracy of circular contact area measurements with thin-film pressure sensors.

    Science.gov (United States)

    Drewniak, Elizabeth I; Crisco, Joseph J; Spenciner, David B; Fleming, Braden C

    2007-01-01

    Contact area is often used to characterize the biomechanical properties of joints, especially in testing of injury and joint replacement. Several methods have been developed to measure contact area, including piezo-resistive thin-film arrays. The purpose of this study was to determine the accuracy with which one of these systems (Tekscan, Inc., South Boston, MA) could measure the contact area of flat-ended circular indenters of varying known sizes. Static loads ranging from 1000 to 7000 N were applied to four flat, circular indenters (1140, 2027, 3167, and 4560 mm(2)) and the contact areas were recorded with Tekscan 5076 sensor. Similar testing was carried out on a 4000 sensor. I-scan software (Tekscan Inc., South Boston, MA) was used to analyze the Tekscan-recorded area measurements. The Tekscan data were also post-processed to filter out sensel signal intensity values that were at least two standard deviations from the average sensel signal intensity values of the sensor matrix. Unprocessed Tekscan measurements with the 5076 sensor had area percent errors ranging from 5% to 27%. The filtering algorithm reduced most errors to less than 1%. Similar trends of improved accuracy with post-filtering were found with the 4000 sensor. While this method of thresholding out the sensels with the lowest signal intensity values may not work for all surfaces and indenter shapes, it provides a new approach to improve the accuracy of contact area measurements collected with the Tekscan system.

  5. Large-area patterning of sub-100 nm epitaxial L10 FePt dots array via nanoimprint lithography

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2015-08-01

    Full Text Available Bit-patterned media, a promising candidate for next generation high density magnetic recording, requires sub-100 nm dots array on a wafer scale, a high degree of patterning control of the size distribution, and a material with high perpendicular anisotropy. In this work, large area (0.75 cm × 0.75 cm dots array was achieved by nanoimprint lithography and ion milling from L10 FePt thin films that are pre-sputtered at 450 °C with both high crystalline quality and good chemical order. The sub-100 nm dots are decoupled from each other and show both narrow size distributions and high coercivity values on the order of 11 kOe. Our work would cast light for the application of bit-patterned media.

  6. Intermodal parametric gain of degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2013-01-01

    Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process.......Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process....

  7. Zinc oxide integrated area efficient high output low power wavy channel thin film transistor

    KAUST Repository

    Hanna, A. N.

    2013-11-26

    We report an atomic layer deposition based zinc oxide channel material integrated thin film transistor using wavy channel architecture allowing expansion of the transistor width in the vertical direction using the fin type features. The experimental devices show area efficiency, higher normalized output current, and relatively lower power consumption compared to the planar architecture. This performance gain is attributed to the increased device width and an enhanced applied electric field due to the architecture when compared to a back gated planar device with the same process conditions.

  8. The European large area ISO survey - III. 90-mu m extragalactic source counts

    DEFF Research Database (Denmark)

    Efstathiou, A.; Oliver, S.; Rowan-Robinson, M.

    2000-01-01

    We present results and source counts at 90 mum extracted from the preliminary analysis of the European Large Area ISO Survey (ELAIS). The survey covered about 12 deg(2) of the sky in four main areas and was carried out with the ISOPHOT instrument onboard the Infrared Space Observatory (ISO...

  9. A large area position sensitive X-ray detector for astrophysical observations

    NARCIS (Netherlands)

    Mels, W.A.; Lowes, P.; Buurmans, H.B.; Brinkman, A.C.; Naber, A.P.; Rook, A.

    1988-01-01

    A large area position sensitive X-ray detector has been developed for use in the coded mask imaging X-ray spectrometer (COMIS) aboard the USSR research module KVANT. The module was launched on March 31, 1987. The detector, having a sensitive area of 256 × 256 mm2, is a sealed multiwire proportional

  10. The European large area ISO survey - III. 90-mu m extragalactic source counts

    DEFF Research Database (Denmark)

    Efstathiou, A.; Oliver, S.; Rowan-Robinson, M.

    2000-01-01

    We present results and source counts at 90 mum extracted from the preliminary analysis of the European Large Area ISO Survey (ELAIS). The survey covered about 12 deg(2) of the sky in four main areas and was carried out with the ISOPHOT instrument onboard the Infrared Space Observatory (ISO...

  11. Estimation of leaf area for large scale phenotyping and modeling of rose genotypes

    NARCIS (Netherlands)

    Gao, M.; Heijden, van der G.W.A.M.; Vos, J.; Eveleens, B.A.; Marcelis, L.F.M.

    2012-01-01

    Leaf area is a major parameter in many physiological and plant modeling studies. When we want to use physiological models in plant breeding, we need to measure the leaf area for a large number of genotypes. This requires a fast and non-destructive method. In this study, we investigated whether for c

  12. The long-term geologic hazards in areas struck by large-magnitude earthquakes

    NARCIS (Netherlands)

    Wasowski, Janusz; Jibson, Randell W.; Huang, Runqiu; van Asch, Theo

    2014-01-01

    Large-magnitude earthquakes occur every year, but most hit remote and uninhabited regions and thus go unnoticed. Although populated areas are affected infrequently by large earthquakes, each time the outcomes are devastating in terms of life and property loss. The human and economic costs of natural

  13. The long-term geologic hazards in areas struck by large-magnitude earthquakes

    NARCIS (Netherlands)

    Wasowski, Janusz; Jibson, Randell W.; Huang, Runqiu; van Asch, Theo

    2014-01-01

    Large-magnitude earthquakes occur every year, but most hit remote and uninhabited regions and thus go unnoticed. Although populated areas are affected infrequently by large earthquakes, each time the outcomes are devastating in terms of life and property loss. The human and economic costs of natural

  14. Detecting Change in Landscape Greenness over Large Areas: An Example for New Mexico, USA

    Science.gov (United States)

    Monitoring and quantifying changes in vegetation cover over large areas using remote sensing can potentially detect large-scale, slow changes (e.g., climate change), as well as more local and rapid changes (e.g., fire, land development). A useful indicator for detecting change i...

  15. Automated spray coating process for the fabrication of large-area artificial opals on textured substrates.

    Science.gov (United States)

    Sprafke, Alexander N; Schneevoigt, Daniela; Seidel, Sophie; Schweizer, Stefan L; Wehrspohn, Ralf B

    2013-05-06

    3D photonic crystals, such as opals, have been shown to have a high potential to increase the efficiency of solar cells by enabling advanced light management concepts. However, methods which comply with the demands of the photovoltaic industry for integration of these structures, i. e. the fabrication in a low-cost, fast, and large-scale manner, are missing up to now. In this work, we present the spray coating of a colloidal suspension on textured substrates and subsequent drying. We fabricated opaline films of much larger lateral dimensions and in much shorter times than what is possible using conventional opal fabrication methods.

  16. Effect of crystallographic orientation on hillock formation in thermally cycled large grain tin films

    Science.gov (United States)

    Koppes, John Patrick

    Tin whiskers and hillocks grow spontaneously from the surfaces of polycrystalline Sn films at room temperature. Whiskers can grow long enough to cause short circuits in electronic devices. We hypothesized that the anisotropies of the crystal structure lead to locally high strain energies that are relieved by the growth of whiskers and hillocks. This research studies hillock formations on large grain Sn-alloy films relative to the crystallographic orientations of the adjacent grains. Large grain films were produced by solidifying 96.5wt% Sn - 3wt% Ag - 0.5wt% Cu solder alloy on a Cu substrate. These surface defects (hillocks) grew predominately at grain boundaries during thermal cycling. The formation of the surface defects between two grains created a pseudo-bi-crystal sample geometry, making it ideal for studying surface defects relative to the local crystallographic orientations and the grains' corresponding anisotropic properties. The crystallographic orientations of the grains were studied with Electron Backscatter Diffraction (EBSD) and Laue micro-diffraction at the Lawrence Berkeley National Laboratory Advanced Light Source. Local orientation studies of the surface defects and the surrounding grains indicated that the surface defects nucleated and grew with low dislocation densities. In addition, the linear surface defect densities along the grain boundaries were measured and observed to change as a function of orientation. The change in linear defect density with respect to orientation was due, in part, to the anisotropy of the coefficient of thermal expansion of β-Sn. In addition, it was important to account for elastic anisotropies. The elastic stresses, strains, and strain energy densities of the microstructures were determined with Object Oriented Finite element analysis. The simulations indicated that during thermal cycling the local stresses exceeded the yield strength. As a result, the highest linear defect densities did not occur at orientations

  17. Tunnel oxide passivated rear contact for large area n-type front junction silicon solar cells providing excellent carrier selectivity

    Directory of Open Access Journals (Sweden)

    Yuguo Tao

    2016-01-01

    Full Text Available Carrier-selective contact with low minority carrier recombination and efficient majority carrier transport is mandatory to eliminate metal-induced recombination for higher energy conversion efficiency for silicon (Si solar cells. In the present study, the carrier-selective contact consists of an ultra-thin tunnel oxide and a phosphorus-doped polycrystalline Si (poly-Si thin film formed by plasma enhanced chemical vapor deposition (PECVD and subsequent thermal crystallization. It is shown that the poly-Si film properties (doping level, crystallization and dopant activation anneal temperature are crucial for achieving excellent contact passivation quality. It is also demonstrated quantitatively that the tunnel oxide plays a critical role in this tunnel oxide passivated contact (TOPCON scheme to realize desired carrier selectivity. Presence of tunnel oxide increases the implied Voc (iVoc by ~ 125 mV. The iVoc value as high as 728 mV is achieved on symmetric structure with TOPCON on both sides. Large area (239 cm2 n-type Czochralski (Cz Si solar cells are fabricated with homogeneous implanted boron emitter and screen-printed contact on the front and TOPCON on the back, achieving 21.2% cell efficiency. Detailed analysis shows that the performance of these cells is mainly limited by boron emitter recombination on the front side.

  18. Low cost solution-based materials processing methods for large area OLEDs and OFETs

    Science.gov (United States)

    Jeong, Jonghwa

    In Part 1, we demonstrate the fabrication of organic light-emitting devices (OLEDs) with precisely patterned pixels by the spin-casting of Alq3 and rubrene thin films with dimensions as small as 10 mum. The solution-based patterning technique produces pixels via the segregation of organic molecules into microfabricated channels or wells. Segregation is controlled by a combination of weak adsorbing characteristics of aliphatic terminated self-assembled monolayers (SAMs) and by centrifugal force, which directs the organic solution into the channel or well. This novel patterning technique may resolve the limitations of pixel resolution in the method of thermal evaporation using shadow masks, and is applicable to the fabrication of large area displays. Furthermore, the patterning technique has the potential to produce pixel sizes down to the limitation of photolithography and micromachining techniques, thereby enabling the fabrication of high-resolution microdisplays. The patterned OLEDs, based upon a confined structure with low refractive index of SiO2, exhibited higher current density than an unpatterned OLED, which results in higher electroluminescence intensity and eventually more efficient device operation at low applied voltages. We discuss the patterning method and device fabrication, and characterize the morphological, optical, and electrical properties of the organic pixels. In part 2, we demonstrate a new growth technique for organic single crystals based on solvent vapor assisted recrystallization. We show that, by controlling the polarity of the solvent vapor and the exposure time in a closed system, we obtain rubrene in orthorhombic to monoclinic crystal structures. This novel technique for growing single crystals can induce phase shifting and alteration of crystal structure and lattice parameters. The organic molecules showed structural change from orthorhombic to monoclinic, which also provided additional optical transition of hypsochromic shift from

  19. Rosin-enabled ultraclean and damage-free transfer of graphene for large-area flexible organic light-emitting diodes

    Science.gov (United States)

    Zhang, Zhikun; Du, Jinhong; Zhang, Dingdong; Sun, Hengda; Yin, Lichang; Ma, Laipeng; Chen, Jiangshan; Ma, Dongge; Cheng, Hui-Ming; Ren, Wencai

    2017-01-01

    The large polymer particle residue generated during the transfer process of graphene grown by chemical vapour deposition is a critical issue that limits its use in large-area thin-film devices such as organic light-emitting diodes. The available lighting areas of the graphene-based organic light-emitting diodes reported so far are usually graphene, good solubility and sufficient strength enable ultraclean and damage-free transfer. The transferred graphene has a low surface roughness with an occasional maximum residue height of about 15 nm and a uniform sheet resistance of 560 Ω per square with about 1% deviation over a large area. Such clean, damage-free graphene has produced the four-inch monolithic flexible graphene-based organic light-emitting diode with a high brightness of about 10,000 cd m−2 that can already satisfy the requirements for lighting sources and displays. PMID:28233778

  20. Simultaneous formation of fine and large-area electrode patterns using screen-offset printing and its application to the patterning on adhesive materials

    Science.gov (United States)

    Nomura, Ken-ichi; Ushijima, Hirobumi; Nagase, Kazuro; Ikedo, Hiroaki; Mitsui, Ryosuke; Sato, Junya; Takahashi, Seiya; Nakajima, Shin-ichiro; Arai, Masahiro; Kurata, Yuji; Iwata, Shiro

    2016-03-01

    Additive-type printing techniques such as gravure-offset printing and screen printing are effective for low-cost and ecofriendly electrode pattern formation. Gravure-offset printing is effective for fine pattern formation with widths on the order of 10-20 µm, whereas screen printing is effective for the formation of large-area patterns. However, it is difficult to simultaneously form fine and large-area patterns using these printing techniques. In this study, we demonstrate that fine (minimum width of 15 µm) and medium- as well as large-area patterns can be formed simultaneously using our developed screen-offset printing technique, which is a combination of screen printing on a silicone blanket and transfer printing from the blanket to a substrate. Furthermore, we demonstrate the application of our method to printing on adhesive materials, which allows electrode formation without applying heat to the film substrate.

  1. Few-mode and large-mode-area fiber with circularly distributed cores

    Science.gov (United States)

    Jin, Wenxing; Ren, Guobin; Jiang, Youchao; Wu, Yue; Xu, Yao; Yang, Yuguang; Shen, Ya; Ren, Wenhua; Jian, Shuisheng

    2017-03-01

    In this paper, a novel few-mode large-mode-area fiber is proposed. This type of fiber consists of 11 conventional cores and 8 air-hole cores circularly arranged around the center core. Few-mode condition equal to strict dual-mode here is available by appropriate adjusting on corepitch, relative refractive index difference and core radius. Large effective area of fundamental mode around 1403.561 μm2 could be achieved by optimization of structural parameters. Bending loss less than 10-3 dB / m is realized when effective area is over 1400 μm2.

  2. CVD diamond wafers as large-area thermoluminescence detectors for measuring the spatial distribution of dose

    Science.gov (United States)

    Marczewska, B.; Bilski, P.; Olko, P.; Olko, P.; Nesládek, M.; Bergonzo, P.; Rbisz, M.; Waligórski, M. P. R.

    2003-09-01

    The applicability of large-area CVD diamond wafers (diameter about 5 cm, thickness about 0.1 mm), read out as thermoluminescence (TL) detectors, for assessing two-dimensional (2-D) dose distribution over their area, was investigated. To obtain 2-D TL images, a special TL reader equipped with large-area planchet and a CCD camera instead of the usual PM tube was developed. Several 2-D TL images: of an alpha source (Am-241), a Ra-226 needle source and a Ru-106 ophthalmic applicator, were measured and high-resolution digital images obtained. Our preliminary results demonstrate the potential capability of large-area CVD diamond wafers, read out as TL detectors, in 2-D dosimetry for medical applications. (

  3. Performance of Aqueous Film Forming Foam (AFFF) on Large-Scale Hydroprocessed Renewable Jet (HRJ) Fuel Fires

    Science.gov (United States)

    2011-12-01

    AFRL-RX-TY-TR-2012-0012 PERFORMANCE OF AQUEOUS FILM FORMING FOAM ( AFFF ) ON LARGE-SCALE HYDROPROCESSED RENEWABLE JET (HRJ) FUEL FIRES ...Performance of Aqueous Film Forming Foam ( AFFF ) on Large-Scale Hydroprocessed Renewable Jet (HRJ) Fuel Fires FA4819-09-C-0030 0602102F 4915 D0 QD103001...Forming Foam ( AFFF )”. AFRL-RX-TY-TR-2011-0101, July 2011 7. Sokri, M., Beyler, CL. “Radiation from Larger Pool Fires ” SFPE Journal of Fire Protection

  4. Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn{sub 4}N epitaxial thin film

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xi; Shigematsu, Kei [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Chikamatsu, Akira, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp; Fukumura, Tomoteru [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Hirose, Yasushi; Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)

    2014-08-18

    We report the electrical transport properties of ferrimagnetic Mn{sub 4}N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn{sub 4}N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m{sup 3}, which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

  5. Large linear magnetoresistance in heavily-doped Nb:SrTiO3 epitaxial thin films

    Science.gov (United States)

    Jin, Hyunwoo; Lee, Keundong; Baek, Seung-Hyub; Kim, Jin-Sang; Cheong, Byung-Ki; Park, Bae Ho; Yoon, Sungwon; Suh, B. J.; Kim, Changyoung; Seo, S. S. A.; Lee, Suyoun

    2016-10-01

    Interaction between electrons has long been a focused topic in condensed-matter physics since it has led to the discoveries of astonishing phenomena, for example, high-Tc superconductivity and colossal magnetoresistance (CMR) in strongly-correlated materials. In the study of strongly-correlated perovskite oxides, Nb-doped SrTiO3 (Nb:SrTiO3) has been a workhorse not only as a conducting substrate, but also as a host possessing high carrier mobility. In this work, we report the observations of large linear magnetoresistance (LMR) and the metal-to-insulator transition (MIT) induced by magnetic field in heavily-doped Nb:STO (SrNb0.2Ti0.8O3) epitaxial thin films. These phenomena are associated with the interplay between the large classical MR due to high carrier mobility and the electronic localization effect due to strong spin-orbit coupling, implying that heavily Nb-doped Sr(Nb0.2Ti0.8)O3 is promising for the application in spintronic devices.

  6. Large interface diffusion in endotaxial growth of MnP films on GaP substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nateghi, N., E-mail: seyyed-nima.nateghi@polymtl.ca; Ménard, D.; Masut, R. A. [Regroupement québécoise sur les matériaux de pointe (RQMP), Département de Génie Physique, Polytechnique Montréal, C.P. 6079, succ. Centre-ville, Montréal, Québec H3C 3A7 (Canada)

    2014-10-07

    The metal organic vapor deposition of MnP films on GaP (100) substrates is shown to have a substantial endotaxial component. A study of the growth time evolution of the endotaxial depths of MnP grains reveals a diffusion-controlled growth with a relatively large diffusion coefficient of Mn in GaP. The value (2.2 ± 1.5) × 10⁻¹⁵ (cm²/s) obtained at 650 °C is at least two orders of magnitude larger than the reported Mn diffusion in bulk GaP. GaP surface mounds provide further indirect evidence that this large diffusion coefficient is concurrent with the out-diffusion of Ga atoms at the growing MnP/GaP interface. No trace of dislocations could be observed at or near this interface, which strongly suggests that Mn diffusion occurs through vacant sites generated by the difference between the crystallographic structures of MnP and GaP.

  7. Large interface diffusion in endotaxial growth of MnP films on GaP substrates

    Science.gov (United States)

    Nateghi, N.; Ménard, D.; Masut, R. A.

    2014-10-01

    The metal organic vapor deposition of MnP films on GaP (100) substrates is shown to have a substantial endotaxial component. A study of the growth time evolution of the endotaxial depths of MnP grains reveals a diffusion-controlled growth with a relatively large diffusion coefficient of Mn in GaP. The value (2.2 ± 1.5) × 10-15 (cm2/s) obtained at 650 °C is at least two orders of magnitude larger than the reported Mn diffusion in bulk GaP. GaP surface mounds provide further indirect evidence that this large diffusion coefficient is concurrent with the out-diffusion of Ga atoms at the growing MnP/GaP interface. No trace of dislocations could be observed at or near this interface, which strongly suggests that Mn diffusion occurs through vacant sites generated by the difference between the crystallographic structures of MnP and GaP.

  8. Simple room-temperature preparation of high-yield large-area graphene oxide.

    Science.gov (United States)

    Huang, N M; Lim, H N; Chia, C H; Yarmo, M A; Muhamad, M R

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.

  9. Productivity and efficiency of economic activity of the Lower Silesia's large area farms in comparison with other large area farms in Poland

    Directory of Open Access Journals (Sweden)

    Stanisław Minta

    2009-01-01

    Full Text Available The paper shows economical and financial situation of the agricultural companies which have most of the grounds in lease. Analysed objects were settled on Lower Silesia (the province in the south – west Poland. The main part of the results of research was about productivity and efficiency of economic resources in these objects. The research was made in years 2000-2002. The results of research in analyzed Lower Silesia’s companies were compared with the best Polish large area farms in order of law and organisation forms: leased farms, private farms and partnerships of Polish public agency AWRSP.

  10. Holographic injection-locking of a broad-area laser diode via a photorefractive thin film device

    NARCIS (Netherlands)

    van Voorst, P.D.; de Wit, M.R.; Offerhaus, Herman L.; Tay, S.; Thomas, J.; Peyghambarian, N.; Boller, Klaus J.

    2007-01-01

    We demonstrate locking of a high power broad area laser diode to a single frequency using holographic feedback from a photorefractive polymer thin-film device for the first time. A four-wave mixing setup is used to generate feedback for the broad area diode at the wavelength of the single frequency

  11. Fast and large-area growth of uniform MoS2 monolayers on molybdenum foils

    Science.gov (United States)

    Tai, Guoan; Zeng, Tian; Yu, Jin; Zhou, Jianxin; You, Yuncheng; Wang, Xufeng; Wu, Hongrong; Sun, Xu; Hu, Tingsong; Guo, Wanlin

    2016-01-01

    A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems.A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the

  12. Functionalization of nanomaterials by non-thermal large area atmospheric pressure plasmas: application to flexible dye-sensitized solar cells

    Science.gov (United States)

    Jung, Heesoo; Park, Jaeyoung; Yoo, Eun Sang; Han, Gill-Sang; Jung, Hyun Suk; Ko, Min Jae; Park, Sanghoo; Choe, Wonho

    2013-08-01

    A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film properties can be obtained by the non-thermal APP method when compared with the thermal sintering process operating at 450 °C. The crystallinity of the anatase TiO2 nanoparticles is significantly improved without thermal agglomeration, while the surface defects such as Ti3+ ions are eliminated, thus providing efficient charge collecting properties for solar cells. Finally, we successfully fabricated a flexible DSSC with an energy conversion efficiency of 4.2% using a transparent plastic substrate. This work demonstrates the potential of non-thermal APP technology in the area of device-level, nano-enabled material manufacturing.A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film

  13. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays

    Science.gov (United States)

    Yardimci, Nezih Tolga; Jarrahi, Mona

    2017-01-01

    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB. PMID:28205615

  14. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays

    Science.gov (United States)

    Yardimci, Nezih Tolga; Jarrahi, Mona

    2017-02-01

    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB.

  15. 3D-Printed Disposable Wireless Sensors with Integrated Microelectronics for Large Area Environmental Monitoring

    KAUST Repository

    Farooqui, Muhammad Fahad

    2017-05-19

    Large area environmental monitoring can play a crucial role in dealing with crisis situations. However, it is challenging as implementing a fixed sensor network infrastructure over large remote area is economically unfeasible. This work proposes disposable, compact, dispersible 3D-printed wireless sensor nodes with integrated microelectronics which can be dispersed in the environment and work in conjunction with few fixed nodes for large area monitoring applications. As a proof of concept, the wireless sensing of temperature, humidity, and H2S levels are shown which are important for two critical environmental conditions namely forest fires and industrial leaks. These inkjet-printed sensors and an antenna are realized on the walls of a 3D-printed cubic package which encloses the microelectronics developed on a 3D-printed circuit board. Hence, 3D printing and inkjet printing are uniquely combined in order to realize a low-cost, fully integrated wireless sensor node.

  16. Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

    Science.gov (United States)

    Guittienne, Ph; Jacquier, R.; Howling, A. A.; Furno, I.

    2017-03-01

    A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmission line coupled to the plasma. This electromagnetic treatment includes mutual inductive coupling using the complex image method, and capacitive matrix coupling between all elements of the resonant network and the plasma. The model reproduces antenna input impedance measurements, with and without plasma, on a 1.2× 1.2 m2 antenna used for large area plasma processing. Analytic expressions are given, and results are obtained by computation of the matrix solution. This method could be used to design planar inductive sources in general, by applying the termination impedances appropriate to each antenna type.

  17. Impact of substrate characteristics on performance of large area plasmonic photoconductive emitters.

    Science.gov (United States)

    Yardimci, Nezih T; Salas, Rodolfo; Krivoy, Erica M; Nair, Hari P; Bank, Seth R; Jarrahi, Mona

    2015-12-14

    We present a comprehensive analysis of terahertz radiation from large area plasmonic photoconductive emitters in relation with characteristics of device substrate. Specifically, we investigate the radiation properties of large area plasmonic photoconductive emitters fabricated on GaAs substrates that exhibit short carrier lifetimes through low-temperature substrate growth and through epitaxially embedded rare-earth arsenide (ErAs and LuAs) nanoparticles in superlattice structures. Our analysis indicates that the utilized substrate composition and growth process for achieving short carrier lifetimes are crucial in determining substrate resistivity, carrier drift velocity, and carrier lifetime, which directly impact optical-to-terahertz conversion efficiency, radiation power, radiation bandwidth, and reliability of large area plasmonic photoconductive emitters.

  18. Fabrication of large-format holograms in dichromated gelatin films for sun control and solar concentrators

    Science.gov (United States)

    Stojanoff, Christo G.; Schuette, Hartmut; Schulat, Jochen; Kubiza, Ralf; Froening, Philipp

    1997-05-01

    Dichromated gelatin layers (DCG) facilitate the design and fabrication of large format holographic optical elements (HOE) of high optical quality and diffraction efficiency. The HOEs are used for the fabrication of spectrally selective solar concentrators and as glazing materials for daylighting and passive sun control in buildings. The suitability of HOEs in these applications depends upon the achievable bandwidth, operating central wavelength, dispersion characteristics and low absorption losses. The HOEs are fabricated on glass or plastic film substrata in a DCG-layer of 5 to 30 micrometer thickness. The layer thickness and the gradient ar precisely controlled during the layer deposition and drying (plus or minus 1 micrometer and 0.1 micrometer/cm for standard layer of 10 micrometer thickness). The production process is based on the fabrication of high quality master holograms that are copied by dry copying procedure. The current manufacturing facilities allow the fabrication of 1 m2 HOEs on glass substratum and a continuous production of HOEs on plastic substratum with a width of 20 cm and length of 50 m. This technology is also used to fabricate holograms for instrumentation optics in metrology and for optical interconnects in multichip modules. The fabricated HOEs exhibit the desired operational characteristics: high diffraction efficiency, small Braggshift, large bandwidth and a central wavelength that may be freely selected over a wide spectral range. In this paper, we present the results from the experimental investigation and theoretical analysis of large number of holograms of the transmissive and reflective types. We discuss the attained angular and wavelength spectra, bandwidths, wavelength shifts and the diffraction efficiencies as functions of the holographic parameters. The HOEs are made for technical applications and are designed to operate in the 300 nm - 1500 m spectral range.

  19. Synthesis and characterization of large specific surface area nanostructured amorphous silica materials.

    Science.gov (United States)

    Marquez-Linares, Francisco; Roque-Malherbe, Rolando M A

    2006-04-01

    Large specific surface area materials attract wide attention because of their applications in adsorption, catalysis, and nanotechnology. In the present study, we describe the synthesis and characterization of nanostructured amorphous silica materials. These materials were obtained by means of a modification of the Stobe-Fink-Bohn (SFB) method. The morphology and essential features of the synthesized materials have been studied using an automated surface area and pore size analyzer and scanning electron microscopy. The existence of a micro/mesoporous structure in the obtained materials has been established. It was also found that the obtained particle packing materials show large specific surface area up to 1,600 m2/g. (To our best knowledge, there is no any reported amorphous silica material with such a higher specific surface area.) The obtained materials could be useful in the manufacture of adsorbents, catalyst supports, and other nanotechnological applications.

  20. Self-assembly of large-scale and ultrathin silver nanoplate films with tunable plasmon resonance properties.

    Science.gov (United States)

    Zhang, Xiao-Yang; Hu, Anming; Zhang, Tong; Lei, Wei; Xue, Xiao-Jun; Zhou, Yunhong; Duley, Walt W

    2011-11-22

    We describe a rapid, simple, room-temperature technique for the production of large-scale metallic thin films with tunable plasmonic properties assembled from size-selected silver nanoplates (SNPs). We outline the properties of a series of ultrathin monolayer metallic films (8-20 nm) self-assembled on glass substrates in which the localized surface plasmon resonance can be tuned over a range from 500 to 800 nm. It is found that the resonance peaks of the films are strongly dependent on the size of the nanoplates and the refractive index of the surrounding dielectric. It is also shown that the bandwidth and the resonance peak of the plasmon resonance spectrum of the metallic films can be engineered by simply controlling aggregation of the SNP. A three-dimensional finite element method was used to investigate the plasmon resonance properties for individual SNPs in different dielectrics and plasmon coupling in SNP aggregates. A 5-17 times enhancement of scattering from these SNP films has been observed experimentally. Our experimental results, together with numerical simulations, indicate that this self-assembly method shows great promise in the production of nanoscale metallic films with enormous electric-field enhancements at visible and near-infrared wavelengths. These may be utilized in biochemical sensing, solar photovoltaic, and optical processing applications.

  1. System and method for interfacing large-area electronics with integrated circuit devices

    Science.gov (United States)

    Verma, Naveen; Glisic, Branko; Sturm, James; Wagner, Sigurd

    2016-07-12

    A system and method for interfacing large-area electronics with integrated circuit devices is provided. The system may be implemented in an electronic device including a large area electronic (LAE) device disposed on a substrate. An integrated circuit IC is disposed on the substrate. A non-contact interface is disposed on the substrate and coupled between the LAE device and the IC. The non-contact interface is configured to provide at least one of a data acquisition path or control path between the LAE device and the IC.

  2. Hybrid Ytterbium-doped large-mode-area photonic crystal fiber amplifier for long wavelengths

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas T.; Poli, Federica

    2012-01-01

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with build-in gain shaping is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core....... Light confinement is achieved by combined index and bandgap guiding, which allows for single-mode operation and gain shaping through distributed spectral filtering of amplified spontaneous emission. The fiber properties are ideal for amplification in the long wavelength regime of the Ytterbium gain...

  3. Tailoring the parametric gain in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2013-01-01

    The spectral width of parametric gain peaks due to degenerate four-wave mixing is investigated numerically in large-mode-area hybrid photonic crystal fibers. The width is varied for a maintained pump wavelength and gain maximum position by tailoring the dispersion.......The spectral width of parametric gain peaks due to degenerate four-wave mixing is investigated numerically in large-mode-area hybrid photonic crystal fibers. The width is varied for a maintained pump wavelength and gain maximum position by tailoring the dispersion....

  4. Data Acquisition and Control System for High-Performance Large-Area CCD Systems

    CERN Document Server

    Afanasieva, I V

    2015-01-01

    Astronomical CCD systems based on second-generation DINACON controllers were developed at the SAO RAS Advanced Design Laboratory more than seven years ago and since then have been in constant operation at the 6-meter and Zeiss-1000 telescopes. Such systems use monolithic large-area CCDs. We describe the software developed for the control of a family of large-area CCD systems equipped with a DINACON-II controller. The software suite serves for acquisition, primary reduction, visualization, and storage of video data, and also for the control, setup, and diagnostics of the CCD system.

  5. Electrochemical preparation of metal microstructures on large areas of etched ion track membranes

    Science.gov (United States)

    Dobrev, D.; Vetter, J.; Angert, N.

    1999-01-01

    A microgalvanic method for metal filling of etched ion tracks in organic foils on large areas is described. The method and the used galvanic cell permit the deposition of stable standing individual metal whiskers with high aspect ratio and a density of 10 5-10 8 per cm 2 on an area of 12.5 cm 2. The method was verified with copper and it is suitable also for various other metals. It can be applied for the replication of etched ion tracks and for the fabrication of microstructures containing large numbers of individual metal whiskers.

  6. A Brief Technical History of the Large-Area Picosecond Photodetector (LAPPD) Collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Adams, B.W.; et al.

    2016-03-06

    The Large Area Picosecond PhotoDetector (LAPPD) Collaboration was formed in 2009 to develop large-area photodetectors capable of time resolutions measured in pico-seconds, with accompanying sub-millimeter spatial resolution. During the next three and one-half years the Collaboration developed the LAPPD design of 20 x 20 cm modules with gains greater than $10^7$ and non-uniformity less than $15\\%$, time resolution less than 50 psec for single photons and spatial resolution of 700~microns in both lateral dimensions. We describe the R\\&D performed to develop large-area micro-channel plate glass substrates, resistive and secondary-emitting coatings, large-area bialkali photocathodes, and RF-capable hermetic packaging. In addition, the Collaboration developed the necessary electronics for large systems capable of precise timing, built up from a custom low-power 15-GigaSample/sec waveform sampling 6-channel integrated circuit and supported by a two-level modular data acquisition system based on Field-Programmable Gate Arrays for local control, data-sparcification, and triggering. We discuss the formation, organization, and technical successes and short-comings of the Collaboration. The Collaboration ended in December 2012 with a transition from R\\&D to commercialization.

  7. A Brief Technical History of the Large-Area Picosecond Photodetector (LAPPD) Collaboration

    CERN Document Server

    Adams, Bernhard W; Bogdan, Mircea; Byrum, Karen; Elagin, Andrey; Elam, Jeffrey W; Frisch, Henry J; Genat, Jean-Francois; Grabas, Herve; Gregar, Joseph; Hahn, Elaine; Heintz, Mary; Insepov, Zinetula; Ivanov, Valentin; Jelinsky, Sharon; Jokely, Slade; Lee, Sun Wu; Mane, Anil U; McPhate, Jason; Minot, Michael J; Murat, Pavel; Nishimura, Kurtis; Northrop, Richard; Obaid, Razib; Oberla, Eric; Ramberg, Erik; Ronzhin, Anatoly; Siegmund, Oswald H; Sellberg, Gregory; Sullivan, Neal T; Tremsin, Anton; Varner, Gary; Veryovkin, Igor; Vostrikov, Alexei; Wagner, Robert G; Walters, Dean; Wang, Hsien-Hau; Wetstein, Matthew; Xi, Junqi; Yusov, Zikri; Zinovev, Alexander

    2016-01-01

    The Large Area Picosecond PhotoDetector (LAPPD) Collaboration was formed in 2009 to develop large-area photodetectors capable of time resolutions measured in pico-seconds, with accompanying sub-millimeter spatial resolution. During the next three and one-half years the Collaboration developed the LAPPD design of 20 x 20 cm modules with gains greater than $10^7$ and non-uniformity less than $15\\%$, time resolution less than 50 psec for single photons and spatial resolution of 700~microns in both lateral dimensions. We describe the R\\&D performed to develop large-area micro-channel plate glass substrates, resistive and secondary-emitting coatings, large-area bialkali photocathodes, and RF-capable hermetic packaging. In addition, the Collaboration developed the necessary electronics for large systems capable of precise timing, built up from a custom low-power 15-GigaSample/sec waveform sampling 6-channel integrated circuit and supported by a two-level modular data acquisition system based on Field-Programmab...

  8. A large-scale deforestation experiment: effects of patch area and isolation on Amazon birds.

    Science.gov (United States)

    Ferraz, Gonçalo; Nichols, James D; Hines, James E; Stouffer, Philip C; Bierregaard, Richard O; Lovejoy, Thomas E

    2007-01-12

    As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

  9. A large-scale deforestation experiment: Effects of patch area and isolation on Amazon birds

    Science.gov (United States)

    Ferraz, G.; Nichols, J.D.; Hines, J.E.; Stouffer, P.C.; Bierregaard, R.O.; Lovejoy, T.E.

    2007-01-01

    As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

  10. Engineering structures and functions of mesenchymal stem cells by suspended large-area graphene nanopatterns

    Science.gov (United States)

    Kim, Jangho; Bae, Won-Gyu; Park, Subeom; Kim, Yeon Ju; Jo, Insu; Park, Sunho; Li Jeon, Noo; Kwak, Woori; Cho, Seoae; Park, Jooyeon; Kim, Hong Nam; Choi, Kyoung Soon; Seonwoo, Hoon; Choung, Yun-Hoon; Choung, Pill-Hoon; Hong, Byung Hee; Chung, Jong Hoon

    2016-09-01

    Inspired by the hierarchical nanofibrous and highly oriented structures of natural extracellular matrices, we report a rational design of chemical vapor deposition graphene-anchored scaffolds that provide both physical and chemical cues in a multilayered organization to control the adhesion and functions of cells for regenerative medicine. These hierarchical platforms are fabricated by transferring large graphene film onto nanogroove patterns. The top graphene layer exhibits planar morphology with slight roughness (∼20 nm between peaks) due to the underlying topography, which results in a suspended structure between the nanoridges. We demonstrate that the adhesion and differentiation of human mesenchymal stem cells were sensitively controlled and enhanced by the both the nanotopography and graphene cues in our scaffolds. Our results indicate that the layered physical and chemical cues can affect the apparent cell behaviors, and can synergistically enhance cell functionality. Therefore, these suspended graphene platforms may be used to advance regenerative medicine.

  11. Large area, screen printed silicon solar cells with selective emitter made by laser overdoping and RTA spin-on glasses

    Energy Technology Data Exchange (ETDEWEB)

    Besi-Vetrella, U.; Pirozzi, L.; Salza, E. [ENEA Casaccia, Roma (Italy); Ginocchietti, G.; Ferrazza, F. [Eurosolare, Roma (Italy); Ventura, L.; Slaoui, A.; Muller, J.C. [CNRS, Strasbourg (France)

    1997-12-31

    In this paper the authors describe their work on a new solar cells fabrication process, based on the use of Rapid Thermal Diffusion (RTD) from spin-on techniques, laser assisted treatments to get selective emitter structures, and screen-printing. The homogeneous lightly doped emitter is first made by rapid thermal diffusion from a P-doped Spin-On Glass (SOG) film. Laser overdoping of contact regions follows, to form the selective emitter structure, by writing the grid pattern using a laser beam. Finally, screen-printing is used to get the contacts; proper solutions have been developed for optical realignment to laser pattern, with a resolution of about 10 microns. The authors have first prepared several batches of small area solar cells, made by using these processes separately, with the aim to study the influence of the main laser and dopant parameters on cell performances. A further step has been to use all the processes together. Large area devices preparation is in progress.

  12. Universal scaling of the charge transport in large-area molecular junctions

    NARCIS (Netherlands)

    Kronemeijer, A.J.; Katsouras, I.; Huisman, E.H.; Hal, P.A. van; Geuns, T.C.T.; Blom, P.W.M.; Leeuw, D.M. de

    2011-01-01

    Charge transport through alkanes and para-phenylene oligomers is investigated in large-area molecular junctions. The molecules are self-assembled in a monolayer and contacted with a top electrode consisting of poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonic acid) (PEDOT:PSS). The complete se

  13. A new acoustic lens material for large area detectors in photoacoustic breast tomography

    NARCIS (Netherlands)

    Xia, W.; Piras, D.; van Hespen, Johannes C.G.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Objectives We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. Background A large surface area detector due to its high

  14. Large-mode-area hybrid photonic crystal fiber amplifier at 1178 nm

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Chen, Mingchen; Shirakawa, Akira

    2015-01-01

    Amplification of 1178 nm light is demonstrated in a large-mode-area single-mode ytterbium-doped hybrid photonic crystal fiber, relying on distributed spectral filtering of spontaneous emission at shorter wavelengths. An output power of 53 W is achieved with 29 dB suppression of parasitic lasing...

  15. Large Mode Area Single Trench Fiber for 2 mu m Operation

    DEFF Research Database (Denmark)

    Jain, Deepak; Sahu, Jayanta K.

    2016-01-01

    Performance of single trench fibers has been investigated using finite-element method at 2 mu m wavelength. Numerical investigations show that an effective single mode operation for large effective area between 3000-4000 mu m(2) and 2000-3000 mu m(2) can be achieved at similar to 40 and similar t...

  16. ITO with embedded silver grids as transparent conductive electrodes for large area organic solar cells

    DEFF Research Database (Denmark)

    Patil, Bhushan Ramesh; Mirsafaei, Mina; Cielecki, Pawel Piotr

    2017-01-01

    In this work, development of semi-transparent electrodes for efficient large area organic solar cells (OSCs) has been demonstrated. Electron beam evaporated silver grids were embedded in commercially available ITO coatings on glass, through a standard negative photolithography process, in order...

  17. Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

    Science.gov (United States)

    Xue, Chao-Hua; Jia, Shun-Tian; Zhang, Jing; Ma, Jian-Zhong

    2010-01-01

    This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted. PMID:27877336

  18. Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

    Directory of Open Access Journals (Sweden)

    Chao-Hua Xue, Shun-Tian Jia, Jing Zhang and Jian-Zhong Ma

    2010-01-01

    Full Text Available This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted.

  19. Large-area fabrication of superhydrophobic surfaces for practical applications: an overview

    OpenAIRE

    Xue, Chao-Hua; Jia, Shun-Tian; Zhang, Jing; Ma, Jian-Zhong

    2010-01-01

    This review summarizes the key topics in the field of large-area fabrication of superhydrophobic surfaces, concentrating on substrates that have been used in commercial applications. Practical approaches to superhydrophobic surface construction and hydrophobization are discussed. Applications of superhydrophobic surfaces are described and future trends in superhydrophobic surfaces are predicted.

  20. A liquid-helium cooled large-area silicon PIN photodiode x-ray detector

    CERN Document Server

    Inoue, Y; Hara, H; Minowa, M; Shimokoshi, F; Inoue, Yoshizumi; Moriyama, Shigetaka; Hara, Hideyuki; Minowa, Makoto; Shimokoshi, Fumio

    1995-01-01

    An x-ray detector using a liquid-helium cooled large-area silicon PIN photodiode has been developed along with a tailor-made charge sensitive preamplifier whose first-stage JFET has been cooled. The operating temperature of the JFET has been varied separately and optimized. The x- and \\gamma-ray energy spectra for an \

  1. High power picosecond vortex laser based on a large-mode-area fiber amplifier.

    Science.gov (United States)

    Tanaka, Yuichi; Okida, Masahito; Miyamoto, Katsuhiko; Omatsu, Takashige

    2009-08-03

    We present the production of picosecond vortex pulses from a stressed large-mode-area fiber amplifier for the first time. 8.5 W picosecond output with a peak power of approximately 12.5 kW was obtained at a pump power of 29 W. 2009 Optical Society of America.

  2. The European Large-Area ISO Survey (ELAIS): the final band-merged catalogue

    DEFF Research Database (Denmark)

    Rowan-Robinson, M.; Lari, C.; Perez-Fournon, I.

    2004-01-01

    We present the final band-merged European Large-Area ISO Survey (ELAIS) Catalogue at 6.7, 15, 90 and 175 mum, and the associated data at U, g', r', i', Z, J, H, K and 20 cm. The origin of the survey, infrared and radio observations, data-reduction and optical identifications are briefly reviewed...

  3. Results from the beam test of the engineering model of the GLAST large area telescope

    Energy Technology Data Exchange (ETDEWEB)

    Couto e Silva, E. do E-mail: eduardo@slac.stanford.edu; Anthony, P.; Arnold, R.; Arrighi, H.; Bloom, E.; Baughman, B.; Bogart, J.; Bosted, P.; Bumala, B.; Chekhtman, A.; Cotton, N.; Crider, A.; Dobbs-Dixon, I.; Djannati-Atai, A.; Dubois, R.; Engovatov, D.; Espigat, P.; Evans, J.L.; Fieguth, T.; Flath, D.; Frigaard, M.; Giebels, B.; Gillespie, S.; Godfrey, G.; Grove, J.E.; Handa, T.; Hansl-Kozanecka, T.; Hernando, J.; Hicks, M.; Hirayama, M.; Johnson, W.N.; Johnson, R.; Kamae, T.; Kroeger, W.; Lauben, D.; Lin, Y.C.; Lindner, T.; Michelson, P.; Moiseev, A.; Nikolaou, M.; Nolan, P.; Odian, A.; Ohsugi, T.; Ormes, J.; Paliaga, G.; Parkinson, P. Saz; Phlips, B.; Ritz, S.; Rock, S.; Russel, J.J.; Sadrozinski, H.; Schalk, T.; Silvis, J.; Szalata, Z.; Terrier, R.; Thompson, D.J.; Tournear, D.M.; Waite, A.P.; Wallace, J.; Williams, S.; Williamson, R.; Winker, G

    2001-11-21

    This paper describes the results of a beam test using the Engineering Model of the GLAST Large Area Telescope, which was installed in a beam of positrons, hadrons and tagged photons at SLAC. The performance of the four subsystems, Anti Coincidence Detector, Silicon Tracker, Calorimeter and Data Acquisition will be described.

  4. Process variations in surface nano geometries manufacture on large area substrates

    DEFF Research Database (Denmark)

    Calaon, Matteo; Hansen, Hans Nørgaard; Tosello, Guido

    2014-01-01

    The need of transporting, treating and measuring increasingly smaller biomedical samples has pushed the integration of a far reaching number of nanofeatures over large substrates size in respect to the conventional processes working area windows. Dimensional stability of nano fabrication processes...

  5. Uniform, large surface-area polarization by modifying corona-electrodes geometry.

    Science.gov (United States)

    Tansel, T; Ener Rusen, S; Rusen, A

    2013-01-01

    We report on the uniform, large scale polarization of ferroelectric materials by a newly designed corona charging technique developing nonconventional electrodes geometry. The results of pyroelectric measurements represented the spatial homogeneity of the polarization attained through a surface area of ~25 cm(2).

  6. Transverse charge transport through DNA oligomers in large-area molecular junctions

    NARCIS (Netherlands)

    Katsouras, I.; Piliego, C.; Blom, P.W.M.; Leeuw, D.M. de

    2013-01-01

    We investigate the nature of charge transport in deoxyribonucleic acid (DNA) using self-assembled layers of DNA in large-area molecular junctions. A protocol was developed that yields dense monolayers where the DNA molecules are not standing upright, but are lying flat on the substrate. As a result

  7. Utility of LiDAR for large area forest inventory applications

    Science.gov (United States)

    Nicholas S. Skowronski; Andrew J. Lister

    2012-01-01

    Multi-resource inventory data are used in conjunction with Light Detection and Ranging (LiDAR) data from the Pennsylvania Department of Natural Resource's PAMAP Program to assess the utility of extensive LiDAR acquisitions for large area forest assessments. Background, justification, and initial study designs are presented. The proposed study will involve three...

  8. Experimental Investigation of Macro-Bending Loss in Large Mode Area Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    Yinian Zhu; Joo Hin Chong; Ping Shum; Chao Lu

    2003-01-01

    We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/Λ and number of air-holes ring in the cladding.

  9. Experimental Investigation of Macro-Bending Loss in Large Mode Area Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    Joo; Hin; Chong; Ping; Shum

    2003-01-01

    We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/∧ and number of air-holes ring in the cladding.

  10. Long period gratings written in large-mode area photonic crystal fiber

    DEFF Research Database (Denmark)

    Nodop, D.; Linke, S.; Jansen, F.

    2008-01-01

    We report for the first time, to the best of our knowledge, on the fabrication and characterization of CO2-laser written long-period gratings in a large-mode area photonic crystal fiber with a core diameter of 25 mu m. The gratings have low insertion losses ( 10 d...

  11. Independent Peer Evaluation of the Large Area Crop Inventory Experiment (LACIE): The LACIE Symposium

    Science.gov (United States)

    1978-01-01

    Yield models and crop estimate accuracy are discussed within the Large Area Crop Inventory Experiment. The wheat yield estimates in the United States, Canada, and U.S.S.R. are emphasized. Experimental results design, system implementation, data processing systems, and applications were considered.

  12. The European Large-Area ISO Survey (ELAIS) : the final band-merged catalogue

    NARCIS (Netherlands)

    Rowan-Robinson, M; Lari, C; Perez-Fournon, [No Value; Gonzalez-Solares, EA; La Franca, F; Vaccari, M; Oliver, S; Gruppioni, C; Ciliegi, P; Heraudeau, P; Serjeant, S; Efstathiou, A; Babbedge, T; Matute, [No Value; Pozzi, F; Franceschini, A; Vaisanen, P; Afonso-Luis, A; Alexander, DM; Almaini, O; Baker, AC; Basilakos, S; Barden, M; del Burgo, C; Bellas-Velidis, [No Value; Cabrera-Guerra, F; Carballo, R; Cesarsky, CJ; Clements, DL; Crockett, H; Danese, L; Dapergolas, A; Drolias, B; Eaton, N; Egami, E; Elbaz, D; Fadda, D; Fox, M; Genzel, R; Goldschmidt, P; Gonzalez-Serrano, JI; Graham, M; Granato, GL; Hatziminaoglou, E; Herbstmeier, U; Joshi, M; Kontizas, E; Kontizas, M; Kotilainen, JK; Kunze, D; Lawrence, A; Lemke, D; Linden-Vornle, MJD; Mann, RG; Marquez, [No Value; Masegosa, J; McMahon, RG; Miley, G; Missoulis, [No Value; Mobasher, B; Morel, T; Norgaard-Nielsen, H; Omont, A; Papadopoulos, P; Puget, JL; Rigopoulou, D; Rocca-Volmerange, B; Sedgwick, N; Silva, L; Sumner, T; Surace, C; Vila-Vilaro, B; Verma, A; Vigroux, L; Villar-Martin, M; Willott, CJ; Carraminana, A; Mujica, R; van der Werf, Paul P.

    2004-01-01

    We present the final band-merged European Large-Area ISO Survey (ELAIS) Catalogue at 6.7, 15, 90 and 175 mum, and the associated data at U, g', r', i', Z, J, H, K and 20 cm. The origin of the survey, infrared and radio observations, data-reduction and optical identifications are briefly reviewed, an

  13. Electron tunneling through alkanedithiol self-assembled monolayers in large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Naber, Ronald C. G.; Jongbloed, Bert; van Hal, Paul A.; Blom, Paul W. M.; de Leeuw, Dago M.; de Boer, Bert

    2007-01-01

    The electrical transport through self-assembled monolayers of alkanedithiols was studied in large-area molecular junctions and described by the Simmons model [Simmons JIG (1963) J Appi Phys 34:1793-1803 and 2581-2590] for tunneling through a practical barrier, i.e., a rectangular barrier with the im

  14. Efficient Mid-Infrared Supercontinuum Generation in Tapered Large Mode Area Chalcogenide Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Petersen, Christian Rosenberg; Engelsholm, Rasmus Dybbro; Markos, Christos

    2017-01-01

    Mid-infrared supercontinuum spanning from 1.8-9  μm with an output power of 41.5 mW is demonstrated by pumping tapered large mode area chalcogenide photonic crystal fibers using a 4 μm optical parametric source....

  15. Large area flexible lighting foils using distributed bare LED dies on polyester substrates

    NARCIS (Netherlands)

    Ende, D.A. van den; Kusters, R.H.L.; Cauwe, M.; Waal, A. van der; Brand, J. van den

    2013-01-01

    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and for backlights for flexible displays. Such a large area lighting device can be made by integrating a matrix of closely spaced LEDs on a flexible foil substrate. Preferably, these LEDs are integrated

  16. Large-area Fabry-Perot modulator based on electro-optic polymers

    DEFF Research Database (Denmark)

    Benter, Nils; Bertram, Ralph Peter; Soergel, Elisabeth

    2006-01-01

    We present a large-area electro-optic Fabry-Perot modulator utilizing a photoaddressable bis-azo polymer placed between two dielectric mirrors with an open aperture of 2 cm. A modulation efficientcy of 1% at an effective modulation voltage of 20 V for a wavelength of 1.55 mymeter is demonstrated...

  17. Unusually large magnetic anisotropy in electrochemically deposited Co-rich Co-Pt films.

    Science.gov (United States)

    Sirtori, V; Cavallotti, P L; Rognoni, R; Xu, X; Zangari, G; Fratesi, G; Trioni, M I; Bernasconi, M

    2011-06-01

    Co-rich Co-Pt films grown by electrodeposition from an amino-nitrite/citrate/glycine electrolyte onto Au(111) substrates apparently grow with a hexagonal structure, with its c-axis directed perpendicular to the surface. The films exhibit a perpendicular magnetic anisotropy (MCA) of the same order of magnitude as the shape anisotropy. Experimental estimates of the MCA result in a higher anisotropy than that reported for bulk materials of the same composition, but similar to values measured in films grown by vacuum methods at relatively high temperature, which partly consist of a high anisotropy, metastable orthorhombic Pmm2 phase. Comparison of valence band X-ray photoelectron spectroscopy measurements on electrodeposited films with density functional theory simulations of the electronic structure of the various reported Co(3)Pt structures support the notion that the films may consist of a mixture of the hexagonal and the Pmm2 structure.

  18. Mapping regional patterns of large forest fires in Wildland-Urban Interface areas in Europe.

    Science.gov (United States)

    Modugno, Sirio; Balzter, Heiko; Cole, Beth; Borrelli, Pasquale

    2016-05-01

    Over recent decades, Land Use and Cover Change (LUCC) trends in many regions of Europe have reconfigured the landscape structures around many urban areas. In these areas, the proximity to landscape elements with high forest fuels has increased the fire risk to people and property. These Wildland-Urban Interface areas (WUI) can be defined as landscapes where anthropogenic urban land use and forest fuel mass come into contact. Mapping their extent is needed to prioritize fire risk control and inform local forest fire risk management strategies. This study proposes a method to map the extent and spatial patterns of the European WUI areas at continental scale. Using the European map of WUI areas, the hypothesis is tested that the distance from the nearest WUI area is related to the forest fire probability. Statistical relationships between the distance from the nearest WUI area, and large forest fire incidents from satellite remote sensing were subsequently modelled by logistic regression analysis. The first European scale map of the WUI extent and locations is presented. Country-specific positive and negative relationships of large fires and the proximity to the nearest WUI area are found. A regional-scale analysis shows a strong influence of the WUI zones on large fires in parts of the Mediterranean regions. Results indicate that the probability of large burned surfaces increases with diminishing WUI distance in touristic regions like Sardinia, Provence-Alpes-Côte d'Azur, or in regions with a strong peri-urban component as Catalunya, Comunidad de Madrid, Comunidad Valenciana. For the above regions, probability curves of large burned surfaces show statistical relationships (ROC value > 0.5) inside a 5000 m buffer of the nearest WUI. Wise land management can provide a valuable ecosystem service of fire risk reduction that is currently not explicitly included in ecosystem service valuations. The results re-emphasise the importance of including this ecosystem service

  19. Techno-economic assessment of novel vanadium redox flow batteries with large-area cells

    Science.gov (United States)

    Minke, Christine; Kunz, Ulrich; Turek, Thomas

    2017-09-01

    The vanadium redox flow battery (VRFB) is a promising electrochemical storage system for stationary megawatt-class applications. The currently limited cell area determined by the bipolar plate (BPP) could be enlarged significantly with a novel extruded large-area plate. For the first time a techno-economic assessment of VRFB in a power range of 1 MW-20 MW and energy capacities of up to 160 MWh is presented on the basis of the production cost model of large-area BPP. The economic model is based on the configuration of a 250 kW stack and the overall system including stacks, power electronics, electrolyte and auxiliaries. Final results include a simple function for the calculation of system costs within the above described scope. In addition, the impact of cost reduction potentials for key components (membrane, electrode, BPP, vanadium electrolyte) on stack and system costs is quantified and validated.

  20. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.