Sample records for nitride ingan samples

  1. Strain relaxation of thick (11–22) semipolar InGaN layer for long wavelength nitride-based device

    SciTech Connect (OSTI)

    Kim, Jaehwan; Min, Daehong; Jang, Jongjin; Lee, Kyuseung; Chae, Sooryong; Nam, Okhyun, E-mail: ohnam@kpu.ac.kr [Advanced Photonics Research Center/LED Technology Center, Department of Nano-Optical Engineering, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 429-793 (Korea, Republic of)

    2014-10-28T23:59:59.000Z

    In this study, the properties of thick stress-relaxed (11–22) semipolar InGaN layers were investigated. Owing to the inclination of growth orientation, misfit dislocations (MDs) occurred at the heterointerface when the strain state of the (11–22) semipolar InGaN layers reached the critical point. We found that unlike InGaN layers based on polar and nonpolar growth orientations, the surface morphologies of the stress-relaxed (11–22) semipolar InGaN layers did not differ from each other and were similar to the morphology of the underlying GaN layer. In addition, misfit strain across the whole InGaN layer was gradually relaxed by MD formation at the heterointerface. To minimize the effect of surface roughness and defects in GaN layers on the InGaN layer, we conducted further investigation on a thick (11–22) semipolar InGaN layer grown on an epitaxial lateral overgrown GaN template. We found that the lateral indium composition across the whole stress-relaxed InGaN layer was almost uniform. Therefore, thick stress-relaxed (11–22) semipolar InGaN layers are suitable candidates for use as underlying layers in long-wavelength devices, as they can be used to control strain accumulation in the heterostructure active region without additional influence of surface roughness.

  2. Q-factor of (In,Ga)N containing III-nitride microcavity grown by multiple deposition techniques

    SciTech Connect (OSTI)

    Ga?evi?, Ž., E-mail: gacevic@isom.upm.es; Calleja, E. [Universidad Politécnica de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Rossbach, G.; Butté, R.; Glauser, M.; Levrat, J.; Cosendey, G.; Carlin, J.-F.; Grandjean, N. [Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Réveret, F. [Institut Pascal, UMR 6602 UBP/CNRS, Clermont Université, 24 Avenue des Landais, F-63177 Aubière Cedex (France)

    2013-12-21T23:59:59.000Z

    A 3?/2 (In,Ga)N/GaN resonant cavity, designed for ?415?nm operation, is grown by molecular beam epitaxy and is sandwiched between a 39.5-period (In,Al)N/GaN distributed Bragg reflector (DBR), grown on c-plane GaN-on-sapphire pseudo-substrate by metal-organic vapor phase epitaxy and an 8-period SiO{sub 2}/ZrO{sub 2} DBR, deposited by electron beam evaporation. Optical characterization reveals an improvement in the cavity emission spectral purity of approximately one order of magnitude due to resonance effects. The combination of spectrophotometric and micro-reflectivity measurements confirms the strong quality (Q)-factor dependence on the excitation spot size. We derive simple analytical formulas to estimate leak and residual absorption losses and propose a simple approach to model the Q-factor and to give a quantitative estimation of the weight of cavity disorder. The model is in good agreement with both transfer-matrix simulation and the experimental findings. We point out that the realization of high Q-factor (In,Ga)N containing microcavities on GaN pseudo-substrates is likely to be limited by the cavity disorder.

  3. Light extraction efficiency enhancement of InGaN quantum wells light-emitting diodes with

    E-Print Network [OSTI]

    Gilchrist, James F.

    Light extraction efficiency enhancement of InGaN quantum wells light-emitting diodes@lehigh.edu Abstract: Improvement of light extraction efficiency of InGaN light emitting diodes (LEDs) using microstructures on the light extraction efficiency of III-Nitride LEDs was studied. Depending on the size

  4. Imaging of InGaN inhomogeneities using visible apertureless near-field scanning optical microscope

    E-Print Network [OSTI]

    Stebounova, Larissa V.; Romanyuk, Yaroslav E.; Chen, Dongxue; Leone, Stephen R.

    2007-01-01T23:59:59.000Z

    InGaN dots deposited on a GaN substrate. 44 In that work, itGaN buffer layer is grown after the nitridation of the substrate.

  5. Growth and optical characterization of multilayers of InGaN quantum dots

    E-Print Network [OSTI]

    Zhu, Tontong; El-Ella, Haitham; Reid, Benjamin; Holmes, Mark; Taylor, Robert; Kappers, Menno; Oliver, Rachel

    2012-01-01T23:59:59.000Z

    carried out using a two photon excitation technique employing a picosecond mode-locked Ti-sapphire laser emitting at 790 nm. Samples were mounted in a cold -finger cryostat that could be cooled down to 4.2 K and the laser was focused through a microscope... GaN quantum dots Article Type: Research Paper Section/Category: General subjects Keywords: B2. InGaN quantum dots; A1. Photoluminescence; B1. Nitrides; A3. Metal-organic vapour phase epitaxy Corresponding Author: Dr Tongtong Zhu, Ph...

  6. Current injection efficiency induced efficiency-droop in InGaN quantum well light-emitting diodes

    E-Print Network [OSTI]

    Gilchrist, James F.

    Current injection efficiency induced efficiency-droop in InGaN quantum well light-emitting diodes Keywords: III-Nitride InGaN QWs Light-emitting diodes Efficiency-droop a b s t r a c t Current injection efficiency and its impact on efficiency-droop in InGaN single quantum well (QW) based light-emitting diodes

  7. IIl-nitride nanowires and heterostructures : growth and optical properties on nanoscale

    E-Print Network [OSTI]

    Zhou, Xiang, Ph. D. Massachusetts Institute of Technology

    2014-01-01T23:59:59.000Z

    Gallium nitride (GaN) and indium gallium nitride (InGaN) nanowires promise potential for further improving the electricity-to-light energy conversion efficiencies in light emitting diodes due to strain relaxation, reduced ...

  8. Low Cost Production of InGaN for Next-Generation Photovoltaic Devices

    SciTech Connect (OSTI)

    Nick M. Sbrockey, Shangzhu Sun, Gary S. Tompa,

    2012-07-09T23:59:59.000Z

    The goal of this project is to develop a low-cost and low-energy technology for production of photovoltaic devices based on InGaN materials. This project builds on the ongoing development by Structured Materials Industries (SMI), of novel thin film deposition technology for Group III-Nitride materials, which is capable of depositing Group-III nitride materials at significantly lower costs and significantly lower energy usage compared to conventional deposition techniques. During this project, SMI demonstrated deposition of GaN and InGaN films using metalorganic sources, and demonstrated compatibility of the process with standard substrate materials and hardware components.

  9. MODIFYING PC1D TO MODEL SPONTANEOUS AND PIEZOELECTRIC POLARIZATION IN III-V NITRIDE SOLAR CELLS

    E-Print Network [OSTI]

    Honsberg, Christiana

    absorption coefficients and radiation tolerance. These features not only enable InGaN to be exploited III-nitrides (AlN, GaN, InN and their alloys) influence the optical and electrical properties as induced-surface/interface charges at the initialization of the solving routine. Simulations of InGaN solar

  10. On the mechanisms of InGaN electron cooler in InGaN/GaN light-emitting diodes

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    . Schubert, Q. Dai, J. K. Kim, E. F. Schubert, J. Piprek, and Y. Park, "Origin of efficiency droop in Ga. Tansu, "Current injection efficiency induced efficiency-droop in InGaN quantum well light. Van de Walle, "Indirect Auger recombination as a cause of efficiency droop in nitride light

  11. Realizing InGaN monolithic solar-photoelectrochemical cells for artificial photosynthesis

    SciTech Connect (OSTI)

    Dahal, R.; Pantha, B. N.; Li, J.; Lin, J. Y.; Jiang, H. X., E-mail: hx.jiang@ttu.edu [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

    2014-04-07T23:59:59.000Z

    InGaN alloys are very promising for solar water splitting because they have direct bandgaps that cover almost the whole solar spectrum. The demonstration of direct solar-to-fuel conversion without external bias with the sunlight being the only energy input would pave the way for realizing photoelectrochemical (PEC) production of hydrogen by using InGaN. A monolithic solar-PEC cell based on InGaN/GaN multiple quantum wells capable to directly generate hydrogen gas under zero bias via solar water splitting is reported. Under the irradiation by a simulated sunlight (1-sun with 100 mW/cm{sup 2}), a 1.5% solar-to-fuel conversion efficiency has been achieved under zero bias, setting a fresh benchmark of employing III-nitrides for artificial photosynthesis. Time dependent hydrogen gas production photocurrent measured over a prolonged period (measured for 7 days) revealed an excellent chemical stability of InGaN in aqueous solution of hydrobromic acid. The results provide insights into the architecture design of using InGaN for artificial photosynthesis to provide usable clean fuel (hydrogen gas) with the sunlight being the only energy input.

  12. Indium incorporation and surface segregation during InGaN growth by molecular beam epitaxy: experiment and theory

    E-Print Network [OSTI]

    Feenstra, Randall

    of 670 C. Following the GaN growth with typical thickness of 200 nm, the substrate temperature is lowered to 580­620 C for the InGaN deposition. GaN(000 ) was grown at 720 C, on sapphire substrates, with pre-growth nitridation of the substrate performed at 1050 C and using a low-temperature GaN buffer layer grown at 550 C

  13. Distinctive Signature of Indium Gallium Nitride Quantum Dot Lasing in Microdisks Cavities

    E-Print Network [OSTI]

    Woolf, Alexander; Aharanovich, Igor; Zhu, Tongtong; Niu, Nan; Wang, Danqing; Oliver, Rachel A; Hu, Evelyn L

    2014-01-01T23:59:59.000Z

    Low threshold lasers realized within compact, high quality optical cavities enable a variety of nanophotonics applications. Gallium nitride (GaN) materials containing indium gallium nitride (InGaN) quantum dots and quantum wells offer an outstanding platform to study light matter interactions and realize practical devices such as efficient light emitting diodes and nanolasers. Despite progress in the growth and characterization of InGaN quantum dots, their advantages as the gain medium in low threshold lasers have not been clearly demonstrated. This work seeks to better understand the reasons for these limitations by focusing on the simpler, limited-mode microdisk cavities, and by carrying out comparisons of lasing dynamics in those cavities using varying gain media including InGaN quantum wells, fragmented quantum wells, and a combination of fragmented quantum wells with quantum dots. For each gain medium, we utilize the distinctive, high quality (Q~5500) modes of the cavities, and the change in the highest ...

  14. Nitrided Metallic Bipolar Plates

    Broader source: Energy.gov (indexed) [DOE]

    nitrided surface treatment. In this approach, an electrically-conductive and corrosion-resistant chromium-nitride surface layer is formed on the bipolar plate component by...

  15. Preparing titanium nitride powder

    DOE Patents [OSTI]

    Bamberger, Carlos E. (Oak Ridge, TN)

    1989-01-01T23:59:59.000Z

    A process for making titanium nitride powder by reaction of titanium phosphates with sodium cyanide.

  16. Nitride fuel performance 

    E-Print Network [OSTI]

    Reynaud, Sylvie Marie Aurel?ie

    2002-01-01T23:59:59.000Z

    The purpose of this work was to assess the potential of nitride fuels in the current context of the nuclear industry. Nitride fuels systems have indeed been for the past decade the subject of new interest from the international community...

  17. Growth of epitaxial iron nitride ultrathin film on zinc-blende gallium nitride

    SciTech Connect (OSTI)

    Pak, J.; Lin, W.; Wang, K.; Chinchore, A.; Shi, M.; Ingram, D. C.; Smith, A. R.; Sun, K.; Lucy, J. M.; Hauser, A. J.; Yang, F. Y. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Physics, The Ohio State University, 191 Woodruff Avenue, Columbus, Ohio 43210 (United States)

    2010-07-15T23:59:59.000Z

    The authors report the growth of iron nitride on zinc-blende gallium nitride using molecular beam epitaxy. First, zinc-blende GaN is grown on a magnesium oxide substrate having (001) orientation; second, an ultrathin layer of FeN is grown on top of the GaN layer. In situ reflection high-energy electron diffraction is used to monitor the surface during growth, and a well-defined epitaxial relationship is observed. Cross-sectional transmission electron microscopy is used to reveal the epitaxial continuity at the gallium nitride-iron nitride interface. Surface morphology of the iron nitride, similar to yet different from that of the GaN substrate, can be described as plateau valley. The FeN chemical stoichiometry is probed using both bulk and surface sensitive methods, and the magnetic properties of the sample are revealed.

  18. Carrier localization and the origin of luminescence in cubic InGaN alloys P. R. C. Kenta)

    E-Print Network [OSTI]

    Kent, Paul

    Carrier localization and the origin of luminescence in cubic InGaN alloys P. R. C. Kenta) and Alex for publication 31 July 2001 The electronic structure and optical properties of cubic nonpiezoelectric InGaN for the emission characteristics of current grown cubic InGaN alloys. © 2001 American Institute of Physics. DOI: 10

  19. InGaN: Direct correlation of nanoscopic morphology features with optical and structural properties

    SciTech Connect (OSTI)

    Koch, Holger, E-mail: holger.koch@osram-os.com [OSRAM Opto Semiconductors GmbH, Leibnizstr. 4, 93055 Regensburg (Germany); GaN Device Technology, RWTH Aachen University, Sommerfeldstraße 24, 52074 Aachen (Germany); Bertram, Frank; August, Olga; Christen, Jürgen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106 Magdeburg (Germany); Pietzonka, Ines; Ahl, Jan-Philipp; Strassburg, Martin; Lugauer, Hans-Jürgen [OSRAM Opto Semiconductors GmbH, Leibnizstr. 4, 93055 Regensburg (Germany); Kalisch, Holger; Vescan, Andrei [GaN Device Technology, RWTH Aachen University, Sommerfeldstraße 24, 52074 Aachen (Germany)

    2014-08-18T23:59:59.000Z

    A comprehensive study on the impact of growth modes on the structural and optical properties of thick InGaN layers suitable for photovoltaic application is presented. Samples grown by metalorganic vapour phase epitaxy with different growth rates and thicknesses have been analyzed. The application of slow growth rates result in smooth layers while higher growth rates induce a meandering surface morphology. Using low-temperature cathodoluminescence, a direct correlation of the morphology to local luminescent properties is obtained: the top of meandering structures reveals a spectrally red-shifted emission compared to the emission wavelength expected from the average indium content determined by X-ray diffraction. The origin of this shift is identified and explained by increased indium incorporation on top of the meander due to a spatially localized compositional pulling effect.

  20. Superconducting structure with layers of niobium nitride and aluminum nitride

    DOE Patents [OSTI]

    Murduck, James M. (Lisle, IL); Lepetre, Yves J. (Lauris, FR); Schuller, Ivan K. (Woodridge, IL); Ketterson, John B. (Evanston, IL)

    1989-01-01T23:59:59.000Z

    A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources.

  1. Superconducting structure with layers of niobium nitride and aluminum nitride

    DOE Patents [OSTI]

    Murduck, J.M.; Lepetre, Y.J.; Schuller, I.K.; Ketterson, J.B.

    1989-07-04T23:59:59.000Z

    A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources. 8 figs.

  2. Plasma chemistries for dry etching GaN, AlN, InGaN and InAlN

    SciTech Connect (OSTI)

    Pearton, S.J.; Vartuli, C.B.; Lee, J.W.; Donovan, S.M.; MacKenzie, J.D.; Abernathy, C.R. [Univ. of Florida, Gainesville, FL (United States); Shul, R.J. [Sandia National Labs., Albuquerque, NM (United States); McLane, G.F. [Army Research Lab., Fort Monmouth, NJ (United States); Ren, F. [AT and T Bell Labs., Murray Hill, NJ (United States)

    1996-04-01T23:59:59.000Z

    Etch rates up to 7,000 {angstrom}/min. for GaN are obtained in Cl{sub 2}/H{sub 2}/Ar or BCl{sub 3}/Ar ECR discharges at 1--3mTorr and moderate dc biases. Typical rates with HI/H{sub 2} are about a factor of three lower under the same conditions, while CH{sub 4}/H{sub 2} produces maximum rates of only {approximately}2,000 {angstrom}/min. The role of additives such as SF{sub 6}, N{sub 2}, H{sub 2} or Ar to the basic chlorine, bromine, iodine or methane-hydrogen plasma chemistries are discussed. Their effect can be either chemical (in forming volatile products with N) or physical (in breaking bonds or enhancing desorption of the etch products). The nitrides differ from conventional III-V`s in that bond-breaking to allow formation of the etch products is a critical factor. Threshold ion energies for the onset of etching of GaN, InGaN and InAlN are {ge} 75 eV.

  3. Reactive DC magnetron sputtering of ultrathin superconducting niobium nitride films

    E-Print Network [OSTI]

    Dane, Andrew E. (Andrew Edward)

    2015-01-01T23:59:59.000Z

    DC reactive magnetron sputtering was used to deposit few-nanometer-thick films of niobium nitride for fabrication of superconducting devices. Over 1000 samples were deposited on a variety of substrates, under various chamber ...

  4. Remarkably reduced efficiency droop by using staircase thin InGaN quantum barriers in InGaN based blue light emitting diodes

    SciTech Connect (OSTI)

    Zhou, Kun; Ikeda, Masao, E-mail: mikeda2013@sinano.ac.cn, E-mail: jpliu2010@sinano.ac.cn; Liu, Jianping, E-mail: mikeda2013@sinano.ac.cn, E-mail: jpliu2010@sinano.ac.cn; Zhang, Shuming; Li, Deyao; Zhang, Liqun; Yang, Hui [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou (China); Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou (China); Cai, Jin; Wang, Hui; Wang, H. B. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou (China); Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou (China); Suzhou Nanojoin Photonics Co., Ltd., Suzhou (China)

    2014-10-27T23:59:59.000Z

    The efficiency droop of InGaN/GaN(InGaN) multiple quantum well (MQW) light emitting diodes (LEDs) with thin quantum barriers (QB) is studied. With thin GaN QB (3?nm–6?nm thickness), the efficiency droop is not improved, which indicates that hole transport cannot be significantly enhanced by the thin GaN QBs. On the contrary, the efficiency droop was remarkably reduced by using a InGaN staircase QB (InGaN SC-QB) MQWs structure where InGaN SC-QBs lower the transport energy barrier of holes. The efficiency droop ratio was as low as 3.3% up to 200?A/cm{sup 2} for the InGaN SC-QB LED. By using monitoring QW with longer wavelength we observe a much uniform carrier distribution in the InGaN SC-QB LEDs, which reveals the mechanism of improvement in the efficiency droop.

  5. Emission mechanisms of bulk GaN and InGaN quantum wells prepared by lateral epitaxial overgrowth

    E-Print Network [OSTI]

    Bowers, John

    Emission mechanisms of bulk GaN and InGaN quantum wells prepared by lateral epitaxial overgrowth S for publication 5 January 1999 The emission mechanisms of bulk GaN and InGaN quantum wells QWs were studied suggest that TDs simply reduce the net volume of light-emitting area. This effect is less pronounced in InGaN

  6. Boron nitride nanotubes

    DOE Patents [OSTI]

    Smith, Michael W. (Newport News, VA); Jordan, Kevin (Newport News, VA); Park, Cheol (Yorktown, VA)

    2012-06-06T23:59:59.000Z

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  7. Nitrided Metallic Bipolar Plates

    SciTech Connect (OSTI)

    Brady, Michael P [ORNL; Tortorelli, Peter F [ORNL; Pihl, Josh A [ORNL; Toops, Todd J [ORNL; More, Karren Leslie [ORNL; Meyer III, Harry M [ORNL; Vitek, John Michael [ORNL; Wang, Heli [National Renewable Energy Laboratory (NREL); Turner, John [National Renewable Energy Laboratory (NREL); Wilson, Mahlon [Los Alamos National Laboratory (LANL); Garzon, Fernando [Los Alamos National Laboratory (LANL); Rockward, Tommy [Los Alamos National Laboratory (LANL); Connors, Dan [GenCell Corp; Rakowski, Jim [Allegheny Ludlum; Gervasio, Don [Arizona State University

    2008-01-01T23:59:59.000Z

    The objectives are: (1) Develop and optimize stainless steel alloys amenable to formation of a protective Cr-nitride surface by gas nitridation, at a sufficiently low cost to meet DOE targets and with sufficient ductility to permit manufacture by stamping. (2) Demonstrate capability of nitridation to yield high-quality stainless steel bipolar plates from thin stamped alloy foils (no significant stamped foil warping or embrittlement). (3) Demonstrate single-cell fuel cell performance of stamped and nitrided alloy foils equivalent to that of machined graphite plates of the same flow-field design ({approx}750-1,000 h, cyclic conditions, to include quantification of metal ion contamination of the membrane electrode assembly [MEA] and contact resistance increase attributable to the bipolar plates). (4) Demonstrate potential for adoption in automotive fuel cell stacks. Thin stamped metallic bipolar plates offer the potential for (1) significantly lower cost than currently-used machined graphite bipolar plates, (2) reduced weight/volume, and (3) better performance and amenability to high volume manufacture than developmental polymer/carbon fiber and graphite composite bipolar plates. However, most metals exhibit inadequate corrosion resistance in proton exchange membrane fuel cell (PEMFC) environments. This behavior leads to high electrical resistance due to the formation of surface oxides and/or contamination of the MEA by metallic ions, both of which can significantly degrade fuel cell performance. Metal nitrides offer electrical conductivities up to an order of magnitude greater than that of graphite and are highly corrosion resistant. Unfortunately, most conventional coating methods (for metal nitrides) are too expensive for PEMFC stack commercialization or tend to leave pinhole defects, which result in accelerated local corrosion and unacceptable performance.

  8. Cubic nitride templates

    DOE Patents [OSTI]

    Burrell, Anthony K; McCleskey, Thomas Mark; Jia, Quanxi; Mueller, Alexander H; Luo, Hongmei

    2013-04-30T23:59:59.000Z

    A polymer-assisted deposition process for deposition of epitaxial cubic metal nitride films and the like is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures under a suitable atmosphere to yield metal nitride films and the like. Such films can be used as templates for the development of high quality cubic GaN based electronic devices.

  9. Downloaded 07 Feb 2012 to 128.180.65.141. Redistribution subject to AIP license or copyright; see http://jap.aip.org/about/rights_and_permissions Improvement in spontaneous emission rates for InGaN quantum

    E-Print Network [OSTI]

    Gilchrist, James F.

    quantum wells on ternary InGaN substrate for light-emitting diodes Jing Zhanga) and Nelson Tansub) Center screening effect. The use of InGaN substrate is expected to result in the ability for growing InGaN QWs mismatch (Da/a) between InGaN QW and GaN substrate/barrier materials. The compressive strain in InGaN QW

  10. Wavelength limits for InGaN quantum wells on GaN

    SciTech Connect (OSTI)

    Pristovsek, Markus, E-mail: markus@pristovsek.de [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)] [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2013-06-17T23:59:59.000Z

    The emission wavelength of coherently strained InGaN quantum wells (QW) is limited by the maximum thickness before relaxation starts. For high indium contents x>40% the resulting wavelength decreases because quantum confinement dominates. For low indium content x<40% the electron hole wave function overlap (and hence radiative emission) is strongly reduced with increasing QW thickness due to the quantum confined Stark effect and imposes another limit. This results in a maximum usable emission wavelength at around 600?nm for QWs with 40%-50% indium content. Relaxed InGaN buffer layers could help to push this further, especially on non- and semi-polar orientations.

  11. Polyorganosilazane preceramic binder development for reaction bonded silicon nitride composites

    SciTech Connect (OSTI)

    Mohr, D.L.; Starr, T.L. [Georgia Tech Research Inst., Atlanta, GA (United States)

    1992-11-01T23:59:59.000Z

    This study has examined the use of two commercially available polyorganosilazanes for application as preceramic binders in a composite composed of silicon carbide fibers in a reaction bonded silicon nitride (RBSN) matrix. Ceramic monolithic and composite samples were produced. Density of monolithic and whisker reinforced RBSN samples containing the polysilazane binder was increased. Mercury intrusion porosimetry revealed a significant decrease in the pore sizes of samples containing a polyorganosilazane binder. Electron micrographs of samples containing the preceramic binder looked similar to control samples containing no precursor. Overall, incorporation of the polysilazane into monolithic and whisker reinforced samples resulted in significantly increased density and decreased porosity. Nitriding of the RBSN was slightly retarded by addition of the polysilazane binder. Samples with the preceramic binders contained increased contents of {alpha} versus {beta}-silicon nitride which may be due to interaction of hydrogen evolved from polysilazane pyrolysis with the nitriding process. Initial efforts to produce continuous fiber reinforced composites via this method have not realized the same improvements in density and porosity which have been observed for monolithic and whisker reinforced samples. Further, the addition of perceramic binder resulted in a more brittle fracture morphology as compared to similar composites made without the binder.

  12. Polyorganosilazane preceramic binder development for reaction bonded silicon nitride composites

    SciTech Connect (OSTI)

    Mohr, D.L.; Starr, T.L. (Georgia Tech Research Inst., Atlanta, GA (United States))

    1992-11-01T23:59:59.000Z

    This study has examined the use of two commercially available polyorganosilazanes for application as preceramic binders in a composite composed of silicon carbide fibers in a reaction bonded silicon nitride (RBSN) matrix. Ceramic monolithic and composite samples were produced. Density of monolithic and whisker reinforced RBSN samples containing the polysilazane binder was increased. Mercury intrusion porosimetry revealed a significant decrease in the pore sizes of samples containing a polyorganosilazane binder. Electron micrographs of samples containing the preceramic binder looked similar to control samples containing no precursor. Overall, incorporation of the polysilazane into monolithic and whisker reinforced samples resulted in significantly increased density and decreased porosity. Nitriding of the RBSN was slightly retarded by addition of the polysilazane binder. Samples with the preceramic binders contained increased contents of [alpha] versus [beta]-silicon nitride which may be due to interaction of hydrogen evolved from polysilazane pyrolysis with the nitriding process. Initial efforts to produce continuous fiber reinforced composites via this method have not realized the same improvements in density and porosity which have been observed for monolithic and whisker reinforced samples. Further, the addition of perceramic binder resulted in a more brittle fracture morphology as compared to similar composites made without the binder.

  13. Superplastic forging nitride ceramics

    DOE Patents [OSTI]

    Panda, Prakash C. (Ithaca, NY); Seydel, Edgar R. (Ithaca, NY); Raj, Rishi (Ithaca, NY)

    1988-03-22T23:59:59.000Z

    The invention relates to producing relatively flaw free silicon nitride ceramic shapes requiring little or no machining by superplastic forging This invention herein was made in part under Department of Energy Grant DE-AC01-84ER80167, creating certain rights in the United States Government. The invention was also made in part under New York State Science and Technology Grant SB1R 1985-10.

  14. Surface plasmon enhanced InGaN light emitter Koichi Okamoto*a

    E-Print Network [OSTI]

    Okamoto, Koichi

    is a very promising method for developing the super bright light emitting diodes (LEDs). Moreover, we foundGaN/GaN, light emitting diode, quantum well, internal quantum efficiency, solid-state light source 1. INTRODUCTION Since 1993, InGaN quantum wells (QW)-based light emitting diodes (LEDs) have been continuously

  15. Enhancement of Radiative Efficiency with Staggered InGaN Quantum Well Light Emitting Diodes

    SciTech Connect (OSTI)

    Tansu, Nelson; Dierolf, Volkmar; Huang, Gensheng; Penn, Samson; Zhao, Hongping; Liu, Guangyu; Li, Xiaohang; Poplawsky, Jonathan

    2011-07-14T23:59:59.000Z

    The technology on the large overlap InGaN QWs developed in this program is currently implemented in commercial technology in enhancing the internal quantum efficiency in major LED industry in US and Asia. The scientific finding from this work supported by the DOE enabled the implementation of this step-like staggered quantum well in the commercial LEDs.

  16. Silicon nitride ceramic comprising samaria and ytterbia

    DOE Patents [OSTI]

    Yeckley, Russell L. (Oakham, MA)

    1996-01-01T23:59:59.000Z

    This invention relates to a sintered silicon nitride ceramic comprising samaria and ytterbia for enhanced toughness.

  17. Finite element simulations of compositionally graded InGaN solar cells G.F. Brown a,b,n

    E-Print Network [OSTI]

    Wu, Junqiao

    , a highly conductive p-type GaN layer provides the hole contact while absorption takes place in the lowerFinite element simulations of compositionally graded InGaN solar cells G.F. Brown a,b,n , J.W. Ager Keywords: Device modeling InGaN Composition grading Heterojunction a b s t r a c t The solar power

  18. Development of White-Light Emitting Active Layers in Nitride Based Heterostructures for Phosphorless Solid State Lighting

    SciTech Connect (OSTI)

    Jan Talbot; Kailash Mishra

    2007-12-31T23:59:59.000Z

    This report provides a summary of research activities carried out at the University of California, San Diego and Central Research of OSRAM SYLVANIA in Beverly, MA partially supported by a research contract from US Department of Energy, DE-FC26-04NT422274. The main objective of this project was to develop III-V nitrides activated by rare earth ions, RE{sup 3+}, which could eliminate the need for phosphors in nitride-based solid state light sources. The main idea was to convert electron-hole pairs injected into the active layer in a LED die to white light directly through transitions within the energy levels of the 4f{sup n}-manifold of RE{sup 3+}. We focused on the following materials: Eu{sup 3+}(red), Tb{sup 3+}(green), Er{sup 3+}(green), Dy{sup 3+}(yellow) and Tm{sup 3+}(blue) in AlN, GaN and alloys of AlN and GaN. Our strategy was to explore candidate materials in powder form first, and then study their behavior in thin films. Thin films of these materials were to be deposited on sapphire substrates using pulsed laser deposition (PLD) and metal organic vapor phase epitaxy (MOVPE). The photo- and cathode-luminescence measurements of these materials were used to investigate their suitability for white light generation. The project proceeded along this route with minor modifications needed to produce better materials and to expedite our progress towards the final goal. The project made the following accomplishments: (1) red emission from Eu{sup 3+}, green from Tb{sup 3+}, yellow from Dy{sup 3+} and blue from Tm{sup 3+} in AlN powders; (2) red emission from Eu{sup 3+} and green emission from Tb{sup 3+} in GaN powder; (3) red emission from Eu{sup 3+} in alloys of GaN and AlN; (4) green emission from Tb{sup 3+} in GaN thin films by PLD; (5) red emission from Eu{sup 3+} and Tb{sup 3+} in GaN thin films deposited by MOVPE; (6) energy transfer from host to RE{sup 3+}; (7) energy transfer from Tb{sup 3+} to Eu{sup 3+} in AlN powders; (8) emission from AlN powder samples codoped with (Eu{sup 3+} ,Tb{sup 3+} ) and (Dy{sup 3+}, Tm{sup 3+}); and (9) white emission from AlN codoped with Dy{sup 3+} and Tm{sup 3+}. We also extensively studied the stabilities of rare earth ions in GaN, and the nature of oxygen defects in GaN and its impact on the optical properties of the host material, using first principles method. Results from these theoretical calculations together with fluorescence measurements from the materials essentially proved the underlying concepts for generating white light using RE{sup 3+}-activated nitrides. For this project, we successfully built a horizontal MOVPE reactor and used it to deposit thin films of undoped and doped nitrides of GaN and InGaN, which is a very significant achievement. Since this reactor was designed and built by in-house experts, it could be easily modified and reassembled for specific research purposes. During this study, it was successfully modified for homogeneous distribution of rare earth ions in a deposited film. It will be an ideal tool for future research involving novel thin film material concepts. We examined carefully the suitability of various metal organic precursors for incorporating RE{sup 3+}. In order to avoid oxygen contamination, several oxygen-free RE{sup 3+} precursors were identified. Both oxygen-free and oxygen- containing metal organic precursors were used for certain rare earth ions (Eu{sup 3+}, Tb{sup 3+} and Er{sup 3+}). However, the suitability of any particular type of precursor for MOVPE deposition was not established during this study, and further study is needed. More intensive research in the future is needed to improve the film quality, and eliminate the separation of rare earth oxide phases during the deposition of thin films by MOVPE. The literature in the area of the chemistry of rare earth ions in nitrides is almost nonexistent, in spite of the significant research on luminescence of RE{sup 3+} in nitrides. Consequently, MOVPE as a method of deposition of RE{sup 3+}-activated nitrides is relatively unexplored. In the following sections of this report, the ou

  19. Comparative study of polar and semipolar (112{sup ¯}2) InGaN layers grown by metalorganic vapour phase epitaxy

    SciTech Connect (OSTI)

    Dinh, Duc V., E-mail: vanduc.dinh@tyndall.ie, E-mail: peter.parbrook@tyndall.ie; Zubialevich, V. Z. [Tyndall National Institute, University College Cork, Lee Matltings, Dyke Parade, Cork (Ireland); Oehler, F.; Kappers, M. J.; Humphreys, C. J. [Department of Materials Science and Metallurgy University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Alam, S. N.; Parbrook, P. J., E-mail: vanduc.dinh@tyndall.ie, E-mail: peter.parbrook@tyndall.ie [Tyndall National Institute, University College Cork, Lee Matltings, Dyke Parade, Cork (Ireland); School of Engineering, University College Cork, Cork (Ireland); Caliebe, M.; Scholtz, F. [Institute of Optoelectronics, Ulm University, Ulm 89069 (Germany)

    2014-10-21T23:59:59.000Z

    InGaN layers were grown simultaneously on (112{sup ¯}2) GaN and (0001) GaN templates by metalorganic vapour phase epitaxy. At higher growth temperature (?750?°C), the indium content (<15%) of the (112{sup ¯}2) and (0001) InGaN layers was similar. However, for temperatures less than 750?°C, the indium content of the (112{sup ¯}2) InGaN layers (15%–26%) were generally lower than those with (0001) orientation (15%–32%). The compositional deviation was attributed to the different strain relaxations between the (112{sup ¯}2) and (0001) InGaN layers. Room temperature photoluminescence measurements of the (112{sup ¯}2) InGaN layers showed an emission wavelength that shifts gradually from 380?nm to 580?nm with decreasing growth temperature (or increasing indium composition). The peak emission wavelength of the (112{sup ¯}2) InGaN layers with an indium content of more than 10% blue-shifted a constant value of ?(50–60) nm when using higher excitation power densities. This blue-shift was attributed to band filling effects in the layers.

  20. Functionalized boron nitride nanotubes

    DOE Patents [OSTI]

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

    2014-04-22T23:59:59.000Z

    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  1. Electrospun Gallium Nitride Nanofibers

    SciTech Connect (OSTI)

    Melendez, Anamaris; Morales, Kristle; Ramos, Idalia [University of Puerto Rico at Humacao, Humacao (Puerto Rico); Campo, Eva [Centre Nacional de Microelectronica, Barcelona (Spain); Santiago, Jorge J. [University of Pennsylvania, Philadelphia (United States)

    2009-04-19T23:59:59.000Z

    The high thermal conductivity and wide bandgap of gallium nitride (GaN) are desirable characteristics in optoelectronics and sensing applications. In comparison to thin films and powders, in the nanofiber morphology the sensitivity of GaN is expected to increase as the exposed area (proportional to the length) increases. In this work we present electrospinning as a novel technique in the fabrication of GaN nanofibers. Electrospinning, invented in the 1930s, is a simple, inexpensive, and rapid technique to produce microscopically long ultrafine fibers. GaN nanofibers are produced using gallium nitrate and dimethyl-acetamide as precursors. After electrospinning, thermal decomposition under an inert atmosphere is used to pyrolyze the polymer. To complete the preparation, the nanofibers are sintered in a tube furnace under a NH{sub 3} flow. Both scanning electron microscopy and profilometry show that the process produces continuous and uniform fibers with diameters ranging from 20 to a few hundred nanometers, and lengths of up to a few centimeters. X-ray diffraction (XRD) analysis shows the development of GaN nanofibers with hexagonal wurtzite structure. Future work includes additional characterization using transmission electron microscopy and XRD to understand the role of precursors and nitridation in nanofiber synthesis, and the use of single nanofibers for the construction of optical and gas sensing devices.

  2. Observations of Rabi oscillations in a non-polar InGaN quantum dot

    SciTech Connect (OSTI)

    Reid, Benjamin P. L., E-mail: benjamin.reid@physics.ox.ac.uk; Chan, Christopher C. S.; Taylor, Robert A. [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Kocher, Claudius [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Konstanz University, Konstanz (Germany); Zhu, Tongtong; Oehler, Fabrice; Emery, Robert; Oliver, Rachel A. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-06-30T23:59:59.000Z

    Experimental observation of Rabi rotations between an exciton excited state and the crystal ground state in a single non-polar InGaN quantum dot is presented. The exciton excited state energy is determined by photoluminescence excitation spectroscopy using two-photon excitation from a pulsed laser. The population of the exciton excited state is seen to undergo power dependent damped Rabi oscillations.

  3. Epitaxial Growth of InGaN Nanowire Arrays for Light Emitting Diodes

    E-Print Network [OSTI]

    Yang, Peidong

    from the substrate. Ni/Au (20 nm / 20 nm) contacts were deposited on the p-GaN substrate in a geometryS1 Epitaxial Growth of InGaN Nanowire Arrays for Light Emitting Diodes Christopher Hahn, Zhaoyu. The straight line represents the Vegard's law correlation between GaN (c = 5.188 Å) and InN (c = 5.709 Å). (b

  4. Photoluminescence microscopy of InGaN quantum wells W. D. Herzog,a)

    E-Print Network [OSTI]

    was grown at a substrate temperature of 670 °C, and was capped with 200 Å of GaN. All of the layers werePhotoluminescence microscopy of InGaN quantum wells W. D. Herzog,a) R. Singh,b) T. D. Moustakas, B is used to assess radiative efficiency and spatial uniformity of GaN/InGaN heterojunctions. Room

  5. Photoelectrochemical water splitting and hydrogen generation by a spontaneously formed InGaN nanowall network

    SciTech Connect (OSTI)

    Alvi, N. H., E-mail: nhalvi@isom.upm.es, E-mail: r.noetzel@isom.upm.es; Soto Rodriguez, P. E. D.; Kumar, Praveen; Gómez, V. J.; Aseev, P.; Nötzel, R., E-mail: nhalvi@isom.upm.es, E-mail: r.noetzel@isom.upm.es [ISOM Institute for Systems Based on Optoelectronics and Microtechnology, ETSI Telecomunicación, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Alvi, A. H. [Department of Physics, Government College University, Faisalabad (Pakistan); Alvi, M. A. [Department of Chemistry, Government College University, Faisalabad (Pakistan); Willander, M. [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, 60174 Norrköping (Sweden)

    2014-06-02T23:59:59.000Z

    We investigate photoelectrochemical water splitting by a spontaneously formed In-rich InGaN nanowall network, combining the material of choice with the advantages of surface texturing for light harvesting by light scattering. The current density for the InGaN-nanowalls-photoelectrode at zero voltage versus the Ag/AgCl reference electrode is 3.4?mA cm{sup ?2} with an incident-photon-to-current-conversion efficiency (IPCE) of 16% under 350?nm laser illumination with 0.075?W·cm{sup ?2} power density. In comparison, the current density for a planar InGaN-layer-photoelectrode is 2?mA cm{sup ?2} with IPCE of 9% at zero voltage versus the Ag/AgCl reference electrode. The H{sub 2} generation rates at zero externally applied voltage versus the Pt counter electrode per illuminated area are 2.8 and 1.61??mol·h{sup ?1}·cm{sup ?2} for the InGaN nanowalls and InGaN layer, respectively, revealing ?57% enhancement for the nanowalls.

  6. Optical Constants ofOptical Constants of Uranium Nitride Thin FilmsUranium Nitride Thin Films

    E-Print Network [OSTI]

    Hart, Gus

    Optical Constants ofOptical Constants of Uranium Nitride Thin FilmsUranium Nitride Thin FilmsDelta--Beta Scatter Plot at 220 eVBeta Scatter Plot at 220 eV #12;Why Uranium Nitride?Why Uranium Nitride? UraniumUranium, uranium,Bombard target, uranium, with argon ionswith argon ions Uranium atoms leaveUranium atoms leave

  7. Structural studies of magnesium nitride fluorides by powder neutron diffraction

    SciTech Connect (OSTI)

    Brogan, Michael A. [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Hughes, Robert W. [WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Smith, Ronald I. [ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Gregory, Duncan H., E-mail: Duncan.Gregory@glasgow.ac.uk [WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2012-01-15T23:59:59.000Z

    Samples of ternary nitride fluorides, Mg{sub 3}NF{sub 3} and Mg{sub 2}NF have been prepared by solid state reaction of Mg{sub 3}N{sub 2} and MgF{sub 2} at 1323-1423 K and investigated by powder X-ray and powder neutron diffraction techniques. Mg{sub 3}NF{sub 3} is cubic (space group: Pm3m) and has a structure related to rock-salt MgO, but with one cation site vacant. Mg{sub 2}NF is tetragonal (space group: I4{sub 1}/amd) and has an anti-LiFeO{sub 2} related structure. Both compounds are essentially ionic and form structures in which nitride and fluoride anions are crystallographically ordered. The nitride fluorides show temperature independent paramagnetic behaviour between 5 and 300 K. - Graphical abstract: Definitive structures of the ternary magnesium nitride fluorides Mg{sub 3}NF{sub 3} and the lower temperature polymorph of Mg{sub 2}NF have been determined from powder neutron diffraction data. The nitride halides are essentially ionic and exhibit weak temperature independent paramagnetic behaviour. Highlights: Black-Right-Pointing-Pointer Definitive structures of Mg{sub 3}NF{sub 3} and Mg{sub 2}NF were determined by neutron diffraction. Black-Right-Pointing-Pointer Nitride and fluoride anions are crystallographically ordered in both structures. Black-Right-Pointing-Pointer Both compounds exhibit weak, temperature independent paramagnetic behaviour. Black-Right-Pointing-Pointer The compounds are essentially ionic with ionicity increasing with F{sup -} content.

  8. Empirical modeling of uranium nitride fuels

    E-Print Network [OSTI]

    Brozak, Daniel Edward

    1987-01-01T23:59:59.000Z

    of this work was to develop an irradiation performance data base for nitride fuels and to provide empirical modeling capabilities for fuel swelling and fission gas release in nitride fuels. The nitride fuels data base represents the most extensive effort... to date to systematically collect, evaluate and analyze irradiation performance data for nitride fuels. The data base will be a valuable tool for all researchers in the advanced fuel modeling field in that it provides a foundation for the construction...

  9. Process for making transition metal nitride whiskers

    DOE Patents [OSTI]

    Bamberger, Carlos E. (Oak Ridge, TN)

    1989-01-01T23:59:59.000Z

    A process for making metal nitrides, particularly titanium nitride whiskers, using a cyanide salt as a reducing agent for a metal compound in the presence of an alkali metal oxide. Sodium cyanide, various titanates and titanium oxide mixed with sodium oxide react to provide titanium nitride whiskers that can be used as reinforcement to ceramic composites.

  10. Process for making transition metal nitride whiskers

    DOE Patents [OSTI]

    Bamberger, C.E.

    1988-04-12T23:59:59.000Z

    A process for making metal nitrides, particularly titanium nitride whiskers, using a cyanide salt as a reducing agent for a metal compound in the presence of an alkali metal oxide. Sodium cyanide, various titanates and titanium oxide mixed with sodium oxide react to provide titanium nitride whiskers that can be used as reinforcement to ceramic composites. 1 fig., 1 tab.

  11. Internal efficiency of InGaN light-emitting diodes: Beyond a quasiequilibrium model

    SciTech Connect (OSTI)

    Chow, Weng W.; Crawford, Mary H.; Tsao, Jeffrey Y.; Kneissl, Michael

    2010-01-01T23:59:59.000Z

    We propose a model to better investigate InGaN light-emitting diode (LED) internal efficiency by extending beyond the usual total carrier density rate equation approach. To illustrate its capability, the model is applied to study intrinsic performance differences between violet and green LEDs. The simulations show performance differences, at different current densities and temperatures, arising from variations in spontaneous emission and heat loss rates. By tracking the momentum-resolved carrier populations, these rate changes are, in turn, traced to differences in bandstructure and plasma heating. The latter leads to carrier distributions that deviate from the quasiequilibrium ones at lattice temperature.

  12. Temperature-dependent efficiency droop of blue InGaN micro-light emitting diodes

    SciTech Connect (OSTI)

    Tian, Pengfei; McKendry, Jonathan J. D.; Herrnsdorf, Johannes; Ferreira, Ricardo; Watson, Ian M.; Gu, Erdan, E-mail: erdan.gu@strath.ac.uk; Dawson, Martin D. [Institute of Photonics, University of Strathclyde, 106 Rottenrow, Glasgow G4 0NW (United Kingdom); Watson, Scott; Kelly, Anthony E. [School of Engineering, University of Glasgow, James Watt South Building, Glasgow G12 8LT (United Kingdom)

    2014-10-27T23:59:59.000Z

    Temperature-dependent trends in radiative and Auger recombination coefficients have been determined at different injection carrier concentrations using InGaN micro-light emitting diodes 40 ?m in diameter. The differential lifetime was obtained first from the measured modulation bandwidth and was then employed to calculate the carrier concentration in the quantum well active region. When the temperature increases, the carrier concentration increases, but both the radiative and Auger recombination coefficients decrease. In addition, the temperature dependence of radiative and Auger recombination coefficients is weaker at a higher injection carrier concentration, which is strongly related to phase space filling.

  13. P-type gallium nitride

    DOE Patents [OSTI]

    Rubin, Michael (Berkeley, CA); Newman, Nathan (Montara, CA); Fu, Tracy (Berkeley, CA); Ross, Jennifer (Pleasanton, CA); Chan, James (Berkeley, CA)

    1997-01-01T23:59:59.000Z

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5.times.10.sup.11 /cm.sup.3 and hole mobilities of about 500 cm.sup.2 /V-sec, measured at 250.degree. K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al.

  14. P-type gallium nitride

    DOE Patents [OSTI]

    Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

    1997-08-12T23:59:59.000Z

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

  15. Investigation into nitrided spur gears

    SciTech Connect (OSTI)

    Yilbas, B.S.; Coban, A.; Nickel, J.; Sunar, M.; Sami, M.; Abdul Aleem, B.J. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)

    1996-12-01T23:59:59.000Z

    The cold forging method has been widely used in industry to produce machine parts. In general, gears are produced by shaping or hobbing. One of the shaping techniques is precision forging, which has several advantages over hobbing. In the present study, cold forging of spur gears from Ti-6Al-4V material is introduced. To improve the surface properties of the resulting gears, plasma nitriding was carried out. Nuclear reaction analysis was carried out to obtain the nitrogen concentration, while the micro-PIXE technique was used to determine the elemental distribution in the matrix after forging and nitriding processes. Scanning electron microscopy and x-ray powder diffraction were used to investigate the metallurgical changes and formation of nitride components in the surface region. Microhardness and friction tests were carried out to measure the hardness depth profile and friction coefficient at the surface. Finally, scoring failure tests were conducted to determine the rotational speed at which the gears failed. Three distinct regions were obtained in the nitride region, and at the initial stages of the scoring tests, failure in surface roughness was observed in the vicinity of the tip of the gear tooth. This occurred at a particular rotational speed and work input.

  16. OPTIMIZATION OF GaN WINDOW LAYER FOR InGaN SOLAR CELLS USING POLARIZATION EFFECT

    E-Print Network [OSTI]

    Honsberg, Christiana

    on the design of wide-band gap GaN window layers for InGaN solar cells. Window layers serve to passivate the top into account during design of the solar cell to improve its collection efficiency. Previously, we have. The present work is a subset of the design optimization process for such solar cells, where we focus

  17. Preparation and atomic structure of reconstructed (0001) InGaN surfaces

    SciTech Connect (OSTI)

    Friedrich, C.; Biermann, A.; Kneissl, M.; Vogt, P. [Institut fuer Festkoerperphysik EW6-1, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Hoffmann, V. [Ferdinand-Braun-Institut, Leibniz-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Esser, N. [Institut fuer Festkoerperphysik EW6-1, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Leibniz-Institut fuer Analytische Wissenschaften - ISAS e.V., Albert-Einstein-Str. 9, 12489 Berlin (Germany)

    2012-08-01T23:59:59.000Z

    The preparation and surface structure of high quality group-III-polar (0001) InGaN layers grown by metal-organic vapor phase epitaxy have been investigated. In order to obtain a clean and well-ordered surface we studied the preparation by annealing at various temperatures under ultra high vacuum and nitrogen-rich conditions in nitrogen-plasma. We show that different InGaN surface reconstructions such as (1 Multiplication-Sign 1), (1 + 1/6), (2 Multiplication-Sign 2), and ({radical}(3) Multiplication-Sign {radical}(3))R30 Degree-Sign can be obtained as observed by low energy electron diffraction. Dependent on the annealing temperature and nitrogen supply these surfaces exhibit significant differences in stoichiometry and morphology as determined by Auger electron spectroscopy and atomic force microscopy measurements. The (1 Multiplication-Sign 1), (2 Multiplication-Sign 2), and ({radical}(3) Multiplication-Sign {radical}(3))R30 Degree-Sign superstructures are terminated by single group-III-adatoms, whereas the (1 + 1/6) exhibits a incommensurate overlayer of group-III-atoms. We show that the (2 Multiplication-Sign 2) and ({radical}(3) Multiplication-Sign {radical}(3))R30 Degree-Sign an In depletion in the first group-III layer and In or Ga adatoms in ontop position. Strain-relaxation is suggested to explain this structure formation.

  18. Nitride based quantum well light-emitting devices having improved current injection efficiency

    DOE Patents [OSTI]

    Tansu, Nelson; Zhao, Hongping; Liu, Guangyu; Arif, Ronald

    2014-12-09T23:59:59.000Z

    A III-nitride based device provides improved current injection efficiency by reducing thermionic carrier escape at high current density. The device includes a quantum well active layer and a pair of multi-layer barrier layers arranged symmetrically about the active layer. Each multi-layer barrier layer includes an inner layer abutting the active layer; and an outer layer abutting the inner layer. The inner barrier layer has a bandgap greater than that of the outer barrier layer. Both the inner and the outer barrier layer have bandgaps greater than that of the active layer. InGaN may be employed in the active layer, AlInN, AlInGaN or AlGaN may be employed in the inner barrier layer, and GaN may be employed in the outer barrier layer. Preferably, the inner layer is thin relative to the other layers. In one embodiment the inner barrier and active layers are 15 .ANG. and 24 .ANG. thick, respectively.

  19. Design and Implementation of Silicon Nitride Valves for Heavy...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Implementation of Silicon Nitride Valves for Heavy Duty Diesel Engines Design and Implementation of Silicon Nitride Valves for Heavy Duty Diesel Engines Poster presentation at the...

  20. amorphous carbon nitride: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Si-rich nitride Er:SRN materials have 3 Carbon Nitride and Conjugated Polymer Composite Materials. Open Access Theses and Dissertations Summary: ??The semiconductor and...

  1. Nitride semiconductor Surface and interface characterization and device design

    E-Print Network [OSTI]

    Zhang, Hongtao

    2006-01-01T23:59:59.000Z

    Lett. 80 , D. Schroder, Semiconductor Material and Devicein III-V Nitride Semiconductors: Applications and Devices ,SAN DIEGO Nitride Semiconductor Surface and Interface

  2. Nanostructure, Chemistry and Crystallography of Iron Nitride...

    Broader source: Energy.gov (indexed) [DOE]

    Nanostructure, Chemistry and Crystallography of Iron Nitride Magnetic Materials by Ultra-High-Resolution Electron Microscopy and Related Methods DOE 2011 Vehicle Technologies...

  3. Silicon nitride having a high tensile strength

    DOE Patents [OSTI]

    Pujari, Vimal K. (Northboro, MA); Tracey, Dennis M. (Medfield, MA); Foley, Michael R. (Oxford, MA); Paille, Norman I. (Oxford, MA); Pelletier, Paul J. (Sutton, MA); Sales, Lenny C. (Grafton, MA); Willkens, Craig A. (Worcester, MA); Yeckley, Russell L. (Latrobe, PA)

    1998-01-01T23:59:59.000Z

    A ceramic body comprising at least about 80 w/o silicon nitride and having a mean tensile strength of at least about 800 MPa.

  4. Nanostructure, Chemistry and Crystallography of Iron Nitride...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Nanostructure, Chemistry and Crystallography of Iron Nitride Magnetic Materials by Ultra-High-Resolution Electron Microscopy and Related Methods Nanostructure, Chemistry and...

  5. Sandia National Laboratories: III-nitride materials

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    III-nitride materials SSLS Scientist Andy Armstrong Receives 2013 Employee Recognition Award On September 9, 2013, in EC, Energy, Energy Efficiency, Events, News, News & Events,...

  6. MECHANISMS OF OPTICAL GAIN IN CUBIC GAN AND INGAN J. Holst, A. Hoffmann, I. Broser, T. Frey*, B. Schttker*, D.J. As*, D. Schikora*, K.

    E-Print Network [OSTI]

    Nabben, Reinhard

    -blende (cubic) GaN and InGaN on GaAs with a common cleavage plane and readily high-quality, low-cost wafers may detailed information about the potential of cubic GaN and InGaN for device applications we performed structure at 3.265 eV in cubic GaN [10]. For the highest pump intensities, the electron- hole

  7. Method of preparation of uranium nitride

    DOE Patents [OSTI]

    Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

    2013-07-09T23:59:59.000Z

    Method for producing terminal uranium nitride complexes comprising providing a suitable starting material comprising uranium; oxidizing the starting material with a suitable oxidant to produce one or more uranium(IV)-azide complexes; and, sufficiently irradiating the uranium(IV)-azide complexes to produce the terminal uranium nitride complexes.

  8. Molten-Salt-Based Growth of Group III Nitrides

    DOE Patents [OSTI]

    Waldrip, Karen E. (Albuquerque, NM); Tsao, Jeffrey Y. (Albuquerque, NM); Kerley, Thomas M. (Albuquerque, NM)

    2008-10-14T23:59:59.000Z

    A method for growing Group III nitride materials using a molten halide salt as a solvent to solubilize the Group-III ions and nitride ions that react to form the Group III nitride material. The concentration of at least one of the nitride ion or Group III cation is determined by electrochemical generation of the ions.

  9. Complete composition tunability of InGaN nanowires using a combinatorial approach

    E-Print Network [OSTI]

    Yang, Peidong

    a horizontal, single-zone tube furnace and two independently controlled heating elements. InCl3, GaCl3 and NH3, particularly for In-rich nitride alloys, which has led to the need for increasingly high ammonia flow rates

  10. X-ray diffraction, optical microscopy, and microhardness studies of gas nitrided titanium alloys and titanium aluminide

    SciTech Connect (OSTI)

    Sha, W. [Metals Research Group, School of Planning, Architecture and Civil Engineering, The Queen's University of Belfast, Belfast BT7 1NN (United Kingdom)], E-mail: w.sha@qub.ac.uk; Haji Mat Don, M.A.; Mohamed, A.; Wu, X.; Siliang, B. [Metals Research Group, School of Planning, Architecture and Civil Engineering, The Queen's University of Belfast, Belfast BT7 1NN (United Kingdom); Zhecheva, A. [Sifco Applied Surface Concepts (UK) Ltd., Division of Sifco Industries, Inc., European Headquarters, 38 Walkers Road, Moons Moat North, Redditch, Worcestershire B98 9HD (United Kingdom)

    2008-03-15T23:59:59.000Z

    Thermochemical surface gas nitriding of {beta}21s, Timetal 205 and a Ti-Al alloy was conducted using differential scanning calorimeter equipment, in nominally pure nitrogen at 850 deg. C and 950 deg. C ({beta}21s), 730 deg. C and 830 deg. C (Timetal 205), and 950 deg. C and 1050 deg. C (Ti-Al) for 1 h, 3 h and 5 h. X-ray diffraction analyses showed new phases formed in the nitrided layer, depending on the alloy and the time and the temperature of nitriding. Microstructures were analyzed using optical microscopy. Cross-sectional microhardness profiles of cross-sectional samples after nitriding were obtained using a Knoop indenter.

  11. Effect of contact metals on the piezoelectric properties of aluminum nitride thin films

    SciTech Connect (OSTI)

    Harman, J.P.; Kabulski, A. (West Virginia U., Morgantown, WV); Pagan, V.R. (West Virginia U., Morgantown, WV); Famouri, K. (West Virginia U., Morgantown, WV); Kasarla, K.R.; Rodak, L.E. (West Virginia U., Morgantown, WV); Hensel, J.P.; Korakakis, D.

    2008-07-01T23:59:59.000Z

    The converse piezoelectric response of aluminum nitride evaluated using standard metal insulator semiconductor structures has been found to exhibit a linear dependence on the work function of the metal used as the top electrode. The apparent d33 of the 150–1100 nm films also depends on the dc bias applied to the samples.

  12. Supplemental Materials: Effective Cleaning of Hexagonal Boron Nitride for Graphene Devices

    E-Print Network [OSTI]

    Goldhaber-Gordon, David

    Supplemental Materials: Effective Cleaning of Hexagonal Boron Nitride for Graphene Devices Andrei G-mail: ag254@stanford.edu; goldhaber-gordon@stanford.edu We discuss in greater detail the sample preparation procedure and transport measure- ments of our graphene/h-BN devices. Flakes of h-BN were produced

  13. Substrate nitridation induced modulations in transport properties of wurtzite GaN/p-Si (100) heterojunctions grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Bhat, Thirumaleshwara N.; Rajpalke, Mohana K.; Krupanidhi, S. B. [Materials Research Centre, Indian Institute of Science, Bangalore- 560012 (India); Roul, Basanta; Kumar, Mahesh [Materials Research Centre, Indian Institute of Science, Bangalore- 560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore-560013 (India)

    2011-11-01T23:59:59.000Z

    Phase pure wurtzite GaN films were grown on Si (100) substrates by introducing a silicon nitride layer followed by low temperature GaN growth as buffer layers. GaN films grown directly on Si (100) were found to be phase mixtured, containing both cubic ({beta}) and hexagonal ({alpha}) modifications. The x-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy studies reveal that the significant enhancement in the structural as well as in the optical properties of GaN films grown with silicon nitride buffer layer grown at 800 deg. C when compared to the samples grown in the absence of silicon nitride buffer layer and with silicon nitride buffer layer grown at 600 deg. C. Core-level photoelectron spectroscopy of Si{sub x}N{sub y} layers reveals the sources for superior qualities of GaN epilayers grown with the high temperature substrate nitridation process. The discussion has been carried out on the typical inverted rectification behavior exhibited by n-GaN/p-Si heterojunctions. Considerable modulation in the transport mechanism was observed with the nitridation conditions. The heterojunction fabricated with the sample of substrate nitridation at high temperature exhibited superior rectifying nature with reduced trap concentrations. Lowest ideality factors ({approx}1.5) were observed in the heterojunctions grown with high temperature substrate nitridation which is attributed to the recombination tunneling at the space charge region transport mechanism at lower voltages and at higher voltages space charge limited current conduction is the dominating transport mechanism. Whereas, thermally generated carrier tunneling and recombination tunneling are the dominating transport mechanisms in the heterojunctions grown without substrate nitridation and low temperature substrate nitridation, respectively.

  14. Low temperature route to uranium nitride

    DOE Patents [OSTI]

    Burrell, Anthony K. (Los Alamos, NM); Sattelberger, Alfred P. (Darien, IL); Yeamans, Charles (Berkeley, CA); Hartmann, Thomas (Idaho Falls, ID); Silva, G. W. Chinthaka (Las Vegas, NV); Cerefice, Gary (Henderson, NV); Czerwinski, Kenneth R. (Henderson, NV)

    2009-09-01T23:59:59.000Z

    A method of preparing an actinide nitride fuel for nuclear reactors is provided. The method comprises the steps of a) providing at least one actinide oxide and optionally zirconium oxide; b) mixing the oxide with a source of hydrogen fluoride for a period of time and at a temperature sufficient to convert the oxide to a fluoride salt; c) heating the fluoride salt to remove water; d) heating the fluoride salt in a nitrogen atmosphere for a period of time and at a temperature sufficient to convert the fluorides to nitrides; and e) heating the nitrides under vacuum and/or inert atmosphere for a period of time sufficient to convert the nitrides to mononitrides.

  15. Method of nitriding refractory metal articles

    DOE Patents [OSTI]

    Tiegs, Terry N. (Lenoir City, TN); Holcombe, Cressie E. (Knoxville, TN); Dykes, Norman L. (Oak Ridge, TN); Omatete, Ogbemi O. (Lagos, NG); Young, Albert C. (Flushing, NY)

    1994-01-01T23:59:59.000Z

    A method of nitriding a refractory-nitride forming metal or metalloid articles and composite articles. A consolidated metal or metalloid article or composite is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article or composite is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article or composite is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid or composite to an article or composite of refractory nitride. In addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating.

  16. Silicon nitride having a high tensile strength

    DOE Patents [OSTI]

    Pujari, V.K.; Tracey, D.M.; Foley, M.R.; Paille, N.I.; Pelletier, P.J.; Sales, L.C.; Willkens, C.A.; Yeckley, R.L.

    1998-06-02T23:59:59.000Z

    A ceramic body is disclosed comprising at least about 80 w/o silicon nitride and having a mean tensile strength of at least about 800 MPa. 4 figs.

  17. High thermal conductivity aluminum nitride ceramic body

    SciTech Connect (OSTI)

    Huseby, I. C.; Bobik, C. F.

    1985-10-15T23:59:59.000Z

    A process for producing a polycrystalline aluminum nitride ceramic body having a porosity of less than about 10% by volume of said body and a thermal conductivity greater than 1.0 W/cm-K at 22/sup 0/ C., which comprises forming a mixture comprised of aluminum nitride powder and an yttrium additive selected from the group consisting of yttrium, yttrium hydride, yttrium nitride and mixtures thereof, said aluminum nitride and yttrium additive having a predetermined oxygen content, said mixture having a composition wherein the equivalent % of yttrium, aluminum, nitrogen and oxygen shapping said mixture into a compact and sintering said compact at a temperature ranging from about 1850/sup 0/ C. to about 2170/sup 0/ C. in an atmosphere selected from the group consisting of nitrogen, argon, hydrogen and mixtures thereof to produce said polycrystalline body.

  18. Smooth cubic commensurate oxides on gallium nitride

    SciTech Connect (OSTI)

    Paisley, Elizabeth A.; Gaddy, Benjamin E.; LeBeau, James M.; Shelton, Christopher T.; Losego, Mark D.; Mita, Seiji; Collazo, Ramón; Sitar, Zlatko; Irving, Douglas L.; Maria, Jon-Paul, E-mail: jpmaria@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Biegalski, Michael D.; Christen, Hans M. [Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-02-14T23:59:59.000Z

    Smooth, commensurate alloys of ?111?-oriented Mg{sub 0.52}Ca{sub 0.48}O (MCO) thin films are demonstrated on Ga-polar, c+ [0001]-oriented GaN by surfactant-assisted molecular beam epitaxy and pulsed laser deposition. These are unique examples of coherent cubic oxide|nitride interfaces with structural and morphological perfection. Metal-insulator-semiconductor capacitor structures were fabricated on n-type GaN. A comparison of leakage current density for conventional and surfactant-assisted growth reveals a nearly 100× reduction in leakage current density for the surfactant-assisted samples. HAADF-STEM images of the MCO|GaN interface show commensurate alignment of atomic planes with minimal defects due to lattice mismatch. STEM and DFT calculations show that GaN c/2 steps create incoherent boundaries in MCO over layers which manifest as two in-plane rotations and determine consequently the density of structural defects in otherwise coherent MCO. This new understanding of interfacial steps between HCP and FCC crystals identifies the steps needed to create globally defect-free heterostructures.

  19. Metal Nitride Diffusion Barriers for Copper Interconnects

    E-Print Network [OSTI]

    Araujo, Roy A.

    2010-01-14T23:59:59.000Z

    nanocrystalline TiN film enhances grain boundary sliding and grain boundary diffusion related creep phenomena, and the ductility of the coatings is also improved. On the other hand, compositional designed TiN based alloys, such as cubic-phase Ti1-xAlxN thin... Nitrides ...................... 26 2.3 Composition and Structures of TiN, TaN and HfN ................. 33 2.4 Nitride Formation, Electronegativity, Atomic Radius and Bonding...

  20. Influence of InGaN sub-quantum-well on performance of InAlN/GaN/InAlN resonant tunneling diodes

    SciTech Connect (OSTI)

    Chen, Haoran; Yang, Lin'an, E-mail: layang@xidian.edu.cn; Hao, Yue [State Key Discipline Laboratory of Wide Bandgap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071 (China)

    2014-08-21T23:59:59.000Z

    The resonant tunneling mechanism of the GaN based resonant tunneling diode (RTD) with an InGaN sub-quantum-well has been investigated by means of numerical simulation. At resonant-state, Electrons in the InGaN/InAlN/GaN/InAlN RTD tunnel from the emitter region through the aligned discrete energy levels in the InGaN sub-quantum-well and GaN main-quantum-well into the collector region. The implantation of the InGaN sub-quantum-well alters the dominant transport mechanism, increase the transmission coefficient and give rise to the peak current and peak-to-valley current ratio. We also demonstrate that the most pronounced negative-differential-resistance characteristic can be achieved by choosing appropriately the In composition of In{sub x}Ga{sub 1?x}N at around x?=?0.06.

  1. The Nitrogen-Nitride Anode.

    SciTech Connect (OSTI)

    Delnick, Frank M.

    2014-10-01T23:59:59.000Z

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  2. Corrosion behavior of mesoporous transition metal nitrides

    SciTech Connect (OSTI)

    Yang, Minghui, E-mail: m.yang@cornell.edu [Department of Chemistry, Cornell University, Ithaca 14853-1301, NY (United States); Allen, Amy J.; Nguyen, Minh T. [Department of Chemistry, Cornell University, Ithaca 14853-1301, NY (United States); Ralston, Walter T. [College of Chemistry, University of California, Berkeley 94720-1460, CA (United States); MacLeod, Michelle J. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139-4307, MA (United States); DiSalvo, Francis J., E-mail: fjd3@cornell.edu [Department of Chemistry, Cornell University, Ithaca 14853-1301, NY (United States)

    2013-09-15T23:59:59.000Z

    Transition metal nitrides (TMN) have many desirable characteristics such as high hardness and good thermal stability under reducing conditions. This work reports an initial survey of the chemical stability of mesoporous TMNs (TM=Nb, V, Cr and Ti) in water at 80 °C at neutral, acidic and alkaline pH. The mesoporous TMNs had specific surface areas of 25–60 m{sup 2}/g with average pore sizes ranging from 10 to 50 nm. The high surface areas of these materials enhance the rate of corrosion per unit mass over that of a bulk material, making detection of corrosion much easier. The products were characterized by Rietveld refinement of powder X-ray diffraction (PXRD) patterns and by scanning electron microscopy (SEM). Several nitrides have corrosion rates that are, within error, not distinguishable from zero (±1 Å/day). Of the nitrides examined, CrN appears to be the most corrosion resistant under acidic conditions. None of the nitrides studied are corrosion resistant under alkaline conditions. - Graphical abstract: Corrosion behavior of mesoporous transition metal nitrides (TM=Nb, V, Cr and Ti) in acidic and alkaline solutions at 80 °C for 2 weeks. Display Omitted - highlights: • Corrosion rates of mesoporous transition metal nitrides in aqueous solution is reported. • The mesoporous TMNs had surface areas of 25–60 m{sup 2}/g. • CrN is the most corrosion resistant under the conditions studied.

  3. Au-free Ohmic Contacts to Gallium Nitride and Graphene 

    E-Print Network [OSTI]

    Ravikirthi, Pradhyumna

    2014-08-10T23:59:59.000Z

    This work deals with Au-free contact metallization schemes for gallium nitride (GaN) and graphene semiconductors. Graphene and gallium nitride are promising materials that can potentially be integrated together in the near future for high frequency...

  4. Au-free Ohmic Contacts to Gallium Nitride and Graphene

    E-Print Network [OSTI]

    Ravikirthi, Pradhyumna

    2014-08-10T23:59:59.000Z

    This work deals with Au-free contact metallization schemes for gallium nitride (GaN) and graphene semiconductors. Graphene and gallium nitride are promising materials that can potentially be integrated together in the near future for high frequency...

  5. Method of manufacture of atomically thin boron nitride

    DOE Patents [OSTI]

    Zettl, Alexander K

    2013-08-06T23:59:59.000Z

    The present invention provides a method of fabricating at least one single layer hexagonal boron nitride (h-BN). In an exemplary embodiment, the method includes (1) suspending at least one multilayer boron nitride across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure. The present invention also provides a method of fabricating single layer hexagonal boron nitride. In an exemplary embodiment, the method includes (1) providing multilayer boron nitride suspended across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure.

  6. Effect of Gallium Nitride Template Layer Strain on the Growth...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Gallium Nitride Template Layer Strain on the Growth of InxGa1-xNGaN Multiple Quantum Well Light Emitting Diodes. Effect of Gallium Nitride Template Layer Strain on the Growth of...

  7. Theoretical Limit to the Laser Threshold Current Density in an InGaN Quantume Well Laser

    SciTech Connect (OSTI)

    Amano, H; Chow, W W; Han, J

    1998-10-09T23:59:59.000Z

    This paper describes an investigation of the spontaneous emission limit to the laser threshold current density in an InGaN quantum well laser. The peak gain and spontaneous emission rate as functions of carrier density are com- puted using a microscopic laser theory. From these quantities, the minimum achievable threshold current density is determined for a given threshold gain. The dependence on quantum well width, and the effects of inhomogeneous broadening due to spatial alloy variations are discussed. Also, comparison with experiments is made.

  8. Influences of excitation-dependent bandstructure changes on InGaN light-emitting diode efficiency

    E-Print Network [OSTI]

    Chow, Weng W

    2011-01-01T23:59:59.000Z

    Bandstructure properties in wurtzite quantum wells can change appreciably with changing carrier density because of screening of quantum-confined Stark effect. An approach for incorporating these changes in an InGaN light-emitting-diode model is described. Bandstructure is computed for different carrier densities by solving Poisson and k\\cdotp equations in the envelop approximation. The information is used as input in a dynamical model for populations in momentum-resolved electron and hole states. Application of the approach is illustrated by modeling device internal quantum efficiency as a function of excitation.

  9. Modeling of temperature and excitation dependences of efficiency in an InGaN light-emitting diode

    E-Print Network [OSTI]

    Chow, Weng W

    2013-01-01T23:59:59.000Z

    The changes in excitation dependence of efficiency with temperature is modeled for a wurtzite InGaN light-emitting diode. The model incorporates bandstructure changes with carrier density arising from screening of quantum-confined Stark effect. Bandstructure is computed by solving Poisson and k.p equations in the envelop approximation. The information is used in a dynamical model for populations in momentum-resolved electron and hole states. Application of the approach shows the interplay of quantum-well and barrier emissions giving rise to shape changes in efficiency versus current density with changing temperature, as observed in some experiments.

  10. Silicon nitride ceramic having high fatigue life and high toughness

    DOE Patents [OSTI]

    Yeckley, Russell L. (Oakham, MA)

    1996-01-01T23:59:59.000Z

    A sintered silicon nitride ceramic comprising between about 0.6 mol % and about 3.2 mol % rare earth as rare earth oxide, and between about 85 w/o and about 95 w/o beta silicon nitride grains, wherein at least about 20% of the beta silicon nitride grains have a thickness of greater than about 1 micron.

  11. In vitro bio-functionality of gallium nitride sensors for radiation biophysics

    SciTech Connect (OSTI)

    Hofstetter, Markus [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Howgate, John [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Schmid, Martin [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Schoell, Sebastian; Sachsenhauser, Matthias [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Adiguezel, Denis [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany); Stutzmann, Martin; Sharp, Ian D. [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany)] [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching (Germany); Thalhammer, Stefan, E-mail: stefan.thalhammer@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)] [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

    2012-07-27T23:59:59.000Z

    Highlights: Black-Right-Pointing-Pointer Gallium nitride based sensors show promising characteristics to monitor cellular parameters. Black-Right-Pointing-Pointer Cell growth experiments reveal excellent biocompatibiltiy of the host GaN material. Black-Right-Pointing-Pointer We present a biofunctionality assay using ionizing radiation. Black-Right-Pointing-Pointer DNA repair is utilized to evaluate material induced alterations in the cellular behavior. Black-Right-Pointing-Pointer GaN shows no bio-functional influence on the cellular environment. -- Abstract: There is an increasing interest in the integration of hybrid bio-semiconductor systems for the non-invasive evaluation of physiological parameters. High quality gallium nitride and its alloys show promising characteristics to monitor cellular parameters. Nevertheless, such applications not only request appropriate sensing capabilities but also the biocompatibility and especially the biofunctionality of materials. Here we show extensive biocompatibility studies of gallium nitride and, for the first time, a biofunctionality assay using ionizing radiation. Analytical sensor devices are used in medical settings, as well as for cell- and tissue engineering. Within these fields, semiconductor devices have increasingly been applied for online biosensing on a cellular and tissue level. Integration of advanced materials such as gallium nitride into these systems has the potential to increase the range of applicability for a multitude of test devices and greatly enhance sensitivity and functionality. However, for such applications it is necessary to optimize cell-surface interactions and to verify the biocompatibility of the semiconductor. In this work, we present studies of mouse fibroblast cell activity grown on gallium nitride surfaces after applying external noxa. Cell-semiconductor hybrids were irradiated with X-rays at air kerma doses up to 250 mGy and the DNA repair dynamics, cell proliferation, and cell growth dynamics of adherent cells were compared to control samples. The impact of ionizing radiation on DNA, along with the associated cellular repair mechanisms, is well characterized and serves as a reference tool for evaluation of substrate effects. The results indicate that gallium nitride does not require specific surface treatments to ensure biocompatibility and suggest that cell signaling is not affected by micro-environmental alterations arising from gallium nitride-cell interactions. The observation that gallium nitride provides no bio-functional influence on the cellular environment confirms that this material is well suited for future biosensing applications without the need for additional chemical surface modification.

  12. Growths of staggered InGaN quantum wells light-emitting diodes emitting at 520525 nm employing graded growth-temperature profile

    E-Print Network [OSTI]

    Gilchrist, James F.

    Growths of staggered InGaN quantum wells light-emitting diodes emitting at 520­525 nm employing current spreading and light extraction in GaN-based light emitting diodes Appl. Phys. Lett. 100, 061107 (2012) Electrically driven nanopyramid green light emitting diode Appl. Phys. Lett. 100, 061106 (2012

  13. Effect of surfactant Sb on In incorporation and thin film morphology of InGaN layers grown by organometallic vapor phase epitaxy

    E-Print Network [OSTI]

    Simons, Jack

    was interpreted as due to a surfactant-induced change of surface phase on the InGaN films. & 2013 Elsevier B of GaN and InN [2]. These problems con- tribute to material defects, inhomogeneous alloying, and phase the lateral epitaxial overgrowth (LEO) of GaN by organome- tallic vapor phase epitaxy (OMVPE). A change

  14. Journal of Crystal Growth 310 (2008) 23202325 Self-assembled InGaN quantum dots on GaN emitting at 520 nm grown

    E-Print Network [OSTI]

    Gilchrist, James F.

    2008-01-01T23:59:59.000Z

    materials, and intrinsic quantum mechanical energy loss of the wavelength conversion process via Stokes, Muhammad Jamil, Nelson Tansu Department of Electrical and Computer Engineering, Center for Optical. These results demonstrates that high In-content InGaN QDs can be grown by MOVPE, and can potentially be utilized

  15. Nitride Fuel Development at the INL

    SciTech Connect (OSTI)

    W.E. Windes

    2007-06-01T23:59:59.000Z

    A new method for fabricating nitride-based fuels for nuclear applications is under development at the Idaho National Laboratory (INL). A primary objective of this research is the development of a process that could be operated as an automated or semi-automated technique reducing costs, worker doses, and eventually improving the final product form. To achieve these goals the fabrication process utilizes a new cryo-forming technique to produce microspheres formed from sub-micron oxide powder to improve material handling issues, yield rapid kinetics for conversion to nitrides, and reduced material impurity levels within the nitride compounds. The microspheres are converted to a nitride form within a high temperature particle fluidizing bed using a carbothermic process that utilizes a hydrocarbon – hydrogen - nitrogen gas mixture. A new monitor and control system using differential pressure changes in the fluidizing gas allows for real-time monitoring and control of the spouted bed reactor during conversion. This monitor and control system can provide real-time data that is used to control the gas flow rates, temperatures, and gas composition to optimize the fluidization of the particle bed. The small size (0.5 µm) of the oxide powders in the microspheres dramatically increases the kinetics of the conversion process yielding reduced process times and temperatures. Initial studies using surrogate ZrO2 powder have yielded conversion efficiencies of 90 -95 % nitride formation with only small levels of oxide and carbide contaminants present. Further studies are being conducted to determine optimal gas mixture ratios, process time, and temperature range for providing complete conversion to a nitride form.

  16. Synthesis and characterization of visible emission from rare-earth doped aluminum nitride, gallium nitride and gallium aluminum nitride powders and thin films

    E-Print Network [OSTI]

    Tao, Jonathan Huai-Tse

    2010-01-01T23:59:59.000Z

    Gallium Nitride Doped With Europium," J. Appl. Phys. , 95Electroluminescence of Europium-doped Gallium Oxide ThinLuminescence Properties of Europium– terbium Double

  17. Photodetectors using III-V nitrides

    DOE Patents [OSTI]

    Moustakas, T.D.

    1998-12-08T23:59:59.000Z

    A bandpass photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The bandpass photodetector detects electromagnetic radiation between a lower transition wavelength and an upper transition wavelength. That detector comprises two low pass photodetectors. The response of the two low pass photodetectors is subtracted to yield a response signal. 24 figs.

  18. Boron nitride solid state neutron detector

    DOE Patents [OSTI]

    Doty, F. Patrick

    2004-04-27T23:59:59.000Z

    The present invention describes an apparatus useful for detecting neutrons, and particularly for detecting thermal neutrons, while remaining insensitive to gamma radiation. Neutrons are detected by direct measurement of current pulses produced by an interaction of the neutrons with hexagonal pyrolytic boron nitride.

  19. Nitride-bonded silicon carbide composite filter

    SciTech Connect (OSTI)

    Thomson, B.N.; DiPietro, S.G.

    1995-12-01T23:59:59.000Z

    The objective of this program is to develop and demonstrate an advanced hot gas filter, using ceramic component technology, with enhanced durability to provide increased resistance to thermal fatigue and crack propagation. The material is silicon carbide fiber reinforced nitride bonded silicon carbide.

  20. Titanium nitride electrodes for thermoelectric generators

    DOE Patents [OSTI]

    Novak, Robert F. (Farmington Hills, MI); Schmatz, Duane J. (Dearborn Heights, MI); Hunt, Thomas K. (Ann Arbor, MI)

    1987-12-22T23:59:59.000Z

    The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a thin film of titanium nitride as an electrode deposited onto solid electrolyte. The invention is also directed to the method of making same.

  1. Gallium nitride junction field-effect transistor

    DOE Patents [OSTI]

    Zolper, John C. (Albuquerque, NM); Shul, Randy J. (Albuquerque, NM)

    1999-01-01T23:59:59.000Z

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  2. Silicon nitride having a high tensile strength

    DOE Patents [OSTI]

    Pujari, Vimal K. (Northboro, MA); Tracey, Dennis M. (Medfield, MA); Foley, Michael R. (Oxford, MA); Paille, Norman I. (Oxford, MA); Pelletier, Paul J. (Millbury, MA); Sales, Lenny C. (Grafton, MA); Willkens, Craig A. (Sterling, MA); Yeckley, Russell L. (Oakham, MA)

    1996-01-01T23:59:59.000Z

    A silicon nitride ceramic comprising: a) inclusions no greater than 25 microns in length, b) agglomerates no greater than 20 microns in diameter, and c) a surface finish of less than about 8 microinches, said ceramic having a four-point flexural strength of at least about 900 MPa.

  3. Photodetectors using III-V nitrides

    DOE Patents [OSTI]

    Moustakas, Theodore D. (Dover, MA)

    1998-01-01T23:59:59.000Z

    A bandpass photodetector using a III-V nitride and having predetermined electrical properties. The bandpass photodetector detects electromagnetic radiation between a lower transition wavelength and an upper transition wavelength. That detector comprises two low pass photodetectors. The response of the two low pass photodetectors is subtracted to yield a response signal.

  4. Gallium nitride junction field-effect transistor

    DOE Patents [OSTI]

    Zolper, J.C.; Shul, R.J.

    1999-02-02T23:59:59.000Z

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  5. EFFECT OF PHASE SEPARATION ON PERFORMANCE OF III-V NITRIDE SOLAR CELLS Omkar Jani1

    E-Print Network [OSTI]

    Honsberg, Christiana

    of a suitable lattice- matched substrate. Although sapphire is the substrate of choice for growth of GaN of the epitaxy. A high n-type defect density in thick InGaN test structures compensates the p-type doping, which is confirmed for thin InGaN test structures with indium compositions as high as 28%, and the resultant test

  6. Enhancing the quantum efficiency of InGaN yellow-green light-emitting diodes by growth interruption

    SciTech Connect (OSTI)

    Du, Chunhua; Ma, Ziguang; Zhou, Junming; Lu, Taiping; Jiang, Yang; Zuo, Peng; Jia, Haiqiang; Chen, Hong, E-mail: hchen@iphy.ac.cn [Key Laboratory for Renewable Energy, Chinese Academy of Sciences, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condense Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-08-18T23:59:59.000Z

    We studied the effect of multiple interruptions during the quantum well growth on emission-efficiency enhancement of InGaN-based yellow-green light emitting diodes on c-plane sapphire substrate. The output power and dominant wavelength at 20?mA are 0.24 mW and 556.3?nm. High resolution x-ray diffraction, photoluminescence, and electroluminescence measurements demonstrate that efficiency enhancement could be partially attributed to crystal quality improvement of the active region resulted from reduced In clusters and relevant defects on the surface of InGaN layer by introducing interruptions. The less tilted energy band in the quantum well is also caused by the decrease of In-content gradient along c-axis resulted from In segregation during the interruptions, which increases spatial overlap of electron-hole wavefunction and thus the internal quantum efficiency. The latter also leads to smaller blueshift of dominant wavelength with current increasing.

  7. Spontaneous formation of highly regular superlattice structure in InGaN epilayers grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Wu, Z. H. [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Graduate School of Engineering, Akasaki Research Center, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Kawai, Y.; Honda, Y.; Yamaguchi, M.; Amano, H. [Graduate School of Engineering, Akasaki Research Center, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Fang, Y.-Y.; Chen, C. Q. [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Kondo, H.; Hori, M. [Graduate School of Engineering, Plasma Nanotechnology Research Center, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)

    2011-04-04T23:59:59.000Z

    In this letter, we have investigated the structural properties of thick InGaN layers grown on GaN by plasma-assisted molecular beam epitaxy, using two growth rates of 1.0 and 3.6 A/s. A highly regular superlattice (SL) structure is found to be spontaneously formed in the film grown at 3.6 A/s but not in the film grown at 1.0 A/s. The faster grown film also exhibits superior structural quality, which could be due to the surface roughness suppression caused by kinetic limitation, and the inhibition of the Frank-Read dislocation generation mechanism within the spontaneously formed SL structure.

  8. Effect of Thermal Annealing in Ammonia on the Properties of InGaN Nanowires with Different Indium Concentrations

    SciTech Connect (OSTI)

    Hahn, Cristopher; Cordones, Amy; Andrews, Sean; Gao, Hanwei; Fu, Anthony; Leone, Stephen; Yang, Peidong

    2012-10-02T23:59:59.000Z

    The utility of an annealing procedure in ammonia ambient is investigated for improving the optical characteristics of InxGa1?xN nanowires (0.07 ? x ? 0.42) grown on c-Al2O3 using a halide chemical vapor deposition method. Morphological studies using scanning electron microscopy confirm that the nanowire morphology is retained after annealing in ammonia at temperatures up to 800 ?C. However, significant indium etching and composition inhomogeneities are observed for higher indium composition nanowires (x = 0.28, 0.42), as measured by energy-dispersive X-ray spectroscopy and Z-contrast scanning transmission electron microscopy. Structural analyses, using X-ray diffraction and high-resolution transmission electron microscopy, indicate that this is a result of the greater thermal instability of higher indium composition nanowires. The effect of these structural changes on the optical quality of InGaN nanowires is examined using steady-state and time-resolved photoluminescence measurements. Annealing in ammonia enhances the integrated photoluminescence intensity of InxGa1?xN nanowires by up to a factor of 4.11 ? 0.03 (for x = 0.42) by increasing the rate of radiative recombination. Fitting of photoluminescence decay curves to a Kohlrausch stretched exponential indicates that this increase is directly related to a larger distribution of recombination rates from composition inhomogeneities caused by annealing. The results demonstrate the role of thermal instability on the improved optical properties of InGaN nanowires annealed in ammonia.

  9. Low-loss binder for hot pressing boron nitride

    DOE Patents [OSTI]

    Maya, Leon (Oak Ridge, TN)

    1991-01-01T23:59:59.000Z

    Borazine derivatives used as low-loss binders and precursors for making ceramic boron nitride structures. The derivative forms the same composition as the boron nitride starting material, thereby filling the voids with the same boron nitride material upon forming and hot pressing. The derivatives have a further advantage of being low in carbon thus resulting in less volatile byproduct that can result in bubble formation during pressing.

  10. Vacancies in fully hydrogenated boron nitride layer: implications...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Using density functional theory, a series of calculations of structural and electronic properties of hydrogen vacancies in a fully hydrogenated boron nitride (fH-BN) layer were...

  11. aluminium nitrides: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    (more) Mutombo, Faustin Kalenda 2012-01-01 22 Carbon Nitride and Conjugated Polymer Composite Materials. Open Access Theses and Dissertations Summary: ??The semiconductor and...

  12. americium nitrides: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    heterostructure Zhang, Hongtao 2006-01-01 19 Carbon Nitride and Conjugated Polymer Composite Materials. Open Access Theses and Dissertations Summary: ??The semiconductor and...

  13. aligned carbon nitride: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    22 23 24 25 Next Page Last Page Topic Index 1 Carbon Nitride and Conjugated Polymer Composite Materials. Open Access Theses and Dissertations Summary: ??The semiconductor and...

  14. III-Nitride Nanowires: Emerging Materials for Lighting and Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    building blocks in LEDs, lasers, sensors, photovoltaics, and high power and high speed electronics. Compared to planar films, III-nitride nanowires have several potential...

  15. Light-Emitting Diodes on Semipolar Bulk Gallium Nitride Substrate...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    semipolar light-emitting diodes (LEDs) on low-defect bulk gallium nitride (GaN) substrates. Peak internal quantum efficiency (IQE) values of greater than 80% are...

  16. Nitrided Metallic Bipolar Plates M.P. Brady (project lead)

    E-Print Network [OSTI]

    Nitrided Metallic Bipolar Plates M.P. Brady (project lead) P. F. Tortorelli Oak Ridge National - $2480 K · ORNL (Lead) · Allegheny Ludlum · Funding for Year 2 · Arizona State University - $2050 K wt.% ­ pre-oxidation key to protective surface nitride formation ­ V segregation into Cr-oxide makes

  17. Dual Templating Synthesis of Mesoporous Titanium Nitride Microspheres

    E-Print Network [OSTI]

    Suslick, Kenneth S.

    Dual Templating Synthesis of Mesoporous Titanium Nitride Microspheres By Jin Ho Bang and Kenneth S pyrolysis (USP) preparation of hierarchically nanostructured titanium nitride (TiN) using an in situ dual as a nitrogen source.[5b,7] Several attempts have been made toward the preparation of nanostructured TiN,[5a,6a

  18. Isothermal nitridation kinetics of TiSi{sub 2} powders

    SciTech Connect (OSTI)

    Roger, J., E-mail: roger@lcts.u-bordeaux1.fr; Maillé, L.; Dourges, M.A.

    2014-04-01T23:59:59.000Z

    The aim of the present work is to determine the kinetics of reaction between TiSi{sub 2} powder and gaseous nitrogen. Isothermal nitridation of TiSi{sub 2} powders with fine (1.4 µm) and medium (4.5 µm) particle size has been studied in pure nitrogen atmosphere from 1000 to 1200 °C for duration up to 50 h. The isothermal nitridation kinetics of TiSi{sub 2} powders were investigated by thermogravimetry. The nitridation rate strongly depends on the particle size and temperature. Smaller size particle exhibits higher nitridation rate due to its larger surface area. The conversion process is complex with nucleation and growth of TiN at the surface of the grain and Si{sub 3}N{sub 4} inside the grain promoted by the Kirkendall effect with an influence of the volume increase. - Graphical abstract: Backscattered electrons image of a transverse TiSi{sub 2} grain nitrurated at 1100 °C for 50 h. - Highlights: • Influence of grain size on TiSi{sub 2} powder nitridation. • Influence of temperature on TiSi{sub 2} powder nitridation. • Experimental measurements of the nitridation kinetics. • An explanation of the nitridation mechanism.

  19. Oxidation Protection of Uranium Nitride Fuel using Liquid Phase Sintering

    SciTech Connect (OSTI)

    Dr. Paul A. Lessing

    2012-03-01T23:59:59.000Z

    Two methods are proposed to increase the oxidation resistance of uranium nitride (UN) nuclear fuel. These paths are: (1) Addition of USi{sub x} (e.g. U3Si2) to UN nitride powder, followed by liquid phase sintering, and (2) 'alloying' UN nitride with various compounds (followed by densification via Spark Plasma Sintering or Liquid Phase Sintering) that will greatly increase oxidation resistance. The advantages (high thermal conductivity, very high melting point, and high density) of nitride fuel have long been recognized. The sodium cooled BR-10 reactor in Russia operated for 18 years on uranium nitride fuel (UN was used as the driver fuel for two core loads). However, the potential advantages (large power up-grade, increased cycle lengths, possible high burn-ups) as a Light Water Reactor (LWR) fuel are offset by uranium nitride's extremely low oxidation resistance (UN powders oxidize in air and UN pellets decompose in hot water). Innovative research is proposed to solve this problem and thereby provide an accident tolerant LWR fuel that would resist water leaks and high temperature steam oxidation/spalling during an accident. It is proposed that we investigate two methods to increase the oxidation resistance of UN: (1) Addition of USi{sub x} (e.g. U{sub 3}Si{sub 2}) to UN nitride powder, followed by liquid phase sintering, and (2) 'alloying' UN nitride with compounds (followed by densification via Spark Plasma Sintering) that will greatly increase oxidation resistance.

  20. Process for producing ceramic nitrides anc carbonitrides and their precursors

    DOE Patents [OSTI]

    Brown, G.M.; Maya, L.

    1987-02-25T23:59:59.000Z

    A process for preparing ceramic nitrides and carbon nitrides in the form of very pure, fine particulate powder. Appropriate precursors is prepared by reaching a transition metal alkylamide with ammonia to produce a mixture of metal amide and metal imide in the form of an easily pyrolyzable precipitate.

  1. High temperature stable W and WSi{sub x} ohmic contacts on GaN and InGaN

    SciTech Connect (OSTI)

    Pearton, S.J.; Abernathy, C.R.; Durbha, A. [Florida Univ., Gainesville, FL (United States)] [and others

    1996-06-01T23:59:59.000Z

    Conventional III-V metallizations chemes such as Au/Ge/Ni, Ti/Pt/Au, and Au/Be were found to display poor thermal stability on both GaN and InGaN, with extensive reaction and contact degradation at {le}500 C. By contrast, W was found to produce low contact resistance ({rho}{sub c}{similar_to}8x10{sup -5}{Omega}cm{sup 2}) to n-GaN. Ga outdiffusion to the surface of thin (500 A) W films was found after annealing at 1,100 C, but not at 1000 C. Interfacial abruptness increased by 300A after 1,100 C annealing. In the case of WSi{sub X} (X=0.45), Ga outdiffusion was absent even at 1,100 C, but again there was interfacial broadening and some phase changes in the WSi{sub X}. On In{sub 0.5}Ga{sub 0.5}N, a minimum specific contact resistivity of 1.5 x10{sup -5}{Omega}cm{sup 2} was obtained for WSi{sub X} annealed at 700 C. These contacts retained a smooth morphology and abrupt interfaces to 800 C. Graded In{sub X}Ga{sub 1-X}N layers have been employed on GaAs/AlGaAs HBTs (heterojunction bipolar transistors), replacing conventional In{sub X}Ga{sub 1-X}As layers. R{sub C} values of 5x10{sup -7}{Omega}cm{sup 2} were obtained for nonalloyed Ti/Pt/Au on the InGaN, and the morphologies were superior to those of InGaAs contact layers. This proves to have significant advantages for fabrication of sub-micron HBTs. Devices with emitter dimensions of 2x5{mu}m{sup 2} displayed gains of 35 for a base doping level of 7x10{sup 19}cm{sup -3} and stable long-term behavior.

  2. Nanowire-templated lateral epitaxial growth of non-polar group III nitrides

    DOE Patents [OSTI]

    Wang, George T. (Albuquerque, NM); Li, Qiming (Albuquerque, NM); Creighton, J. Randall (Albuquerque, NM)

    2010-03-02T23:59:59.000Z

    A method for growing high quality, nonpolar Group III nitrides using lateral growth from Group III nitride nanowires. The method of nanowire-templated lateral epitaxial growth (NTLEG) employs crystallographically aligned, substantially vertical Group III nitride nanowire arrays grown by metal-catalyzed metal-organic chemical vapor deposition (MOCVD) as templates for the lateral growth and coalescence of virtually crack-free Group III nitride films. This method requires no patterning or separate nitride growth step.

  3. Hard and low friction nitride coatings and methods for forming the same

    DOE Patents [OSTI]

    Erdemir, Ali (Naperville, IL); Urgen, Mustafa (Istanbul, TR); Cakir, Ali Fuat (Istanbul, TR); Eryilmaz, Osman Levent (Bolingbrook, IL); Kazmanli, Kursat (Istanbul, TR); Keles, Ozgul (Istanbul, TR)

    2007-05-01T23:59:59.000Z

    An improved coating material possessing super-hard and low friction properties and a method for forming the same. The improved coating material includes the use of a noble metal or soft metal homogeneously distributed within a hard nitride material. The addition of small amounts of such metals into nitrides such as molybdenum nitride, titanium nitride, and chromium nitride results in as much as increasing of the hardness of the material as well as decreasing the friction coefficient and increasing the oxidation resistance.

  4. Improved superconducting qubit coherence using titanium nitride

    E-Print Network [OSTI]

    J. Chang; M. R. Vissers; A. D. Corcoles; M. Sandberg; J. Gao; David W. Abraham; Jerry M. Chow; Jay M. Gambetta; M. B. Rothwell; G. A. Keefe; Matthias Steffen; D. P. Pappas

    2013-03-17T23:59:59.000Z

    We demonstrate enhanced relaxation and dephasing times of transmon qubits, up to ~ 60 \\mu s by fabricating the interdigitated shunting capacitors using titanium nitride (TiN). Compared to lift-off aluminum deposited simultaneously with the Josephson junction, this represents as much as a six-fold improvement and provides evidence that previous planar transmon coherence times are limited by surface losses from two-level system (TLS) defects residing at or near interfaces. Concurrently, we observe an anomalous temperature dependent frequency shift of TiN resonators which is inconsistent with the predicted TLS model.

  5. Synthesis, Crystal Structure, and Elastic Properties of Novel Tungsten Nitrides

    SciTech Connect (OSTI)

    Wang, Shanmin; Yu, Xiaohui; Lin, Zhijun; Zhang, Ruifeng; He, Duanwei; Qin, Jiaqian; Zhu, Jinlong; Han, Jiantao; Wang, Lin; Mao, Ho-kwang; Zhang, Jianzhong; Zhao, Yusheng (UNLV); (Ehime U); (CIW); (Sichuan U.); (LANL)

    2012-12-13T23:59:59.000Z

    Among transition metal nitrides, tungsten nitrides possess unique and/or superior chemical, mechanical, and thermal properties. Preparation of these nitrides, however, is challenging because the incorporation of nitrogen into tungsten lattice is thermodynamically unfavorable at atmospheric pressure. To date, most materials in the W-N system are in the form of thin films produced by nonequilibrium processes and are often poorly crystallized, which severely limits their use in diverse technological applications. Here we report synthesis of tungsten nitrides through new approaches involving solid-state ion exchange and nitrogen degassing under pressure. We unveil a number of novel nitrides including hexagonal and rhombohedral W{sub 2}N{sub 3}. The final products are phase-pure and well-crystallized in bulk forms. For hexagonal W{sub 2}N{sub 3}, hexagonal WN, and cubic W3N4, they exhibit elastic properties rivaling or even exceeding cubic-BN. All four nitrides are prepared at a moderate pressure of 5 GPa, the lowest among high-pressure synthesis of transition metal nitrides, making it practically feasible for massive and industrial-scale production.

  6. Vibronic fine structure in high-resolution x-ray absorption spectra from ion-bombarded boron nitride nanotubes

    SciTech Connect (OSTI)

    Petravic, Mladen; Peter, Robert; Varasanec, Marijana [Department of Physics and Center for Micro and Nano Sciences and Technologies, University of Rijeka, 51000 Rijeka (Croatia); Li Luhua; Chen Ying [Institute for Technology Research and Innovation, Deakin University, Geelong Waurn Ponds Campus, 3217 (Australia); Cowie, Bruce C. C. [Australian Synchrotron, Clayton VIC 3168 (Australia)

    2013-05-15T23:59:59.000Z

    The authors have applied high-resolution near-edge x-ray absorption fine structure measurements around the nitrogen K-edge to study the effects of ion-bombardment on near-surface properties of boron nitride nanotubes. A notable difference has been observed between surface sensitive partial electron yield (PEY) and bulk sensitive total electron yield (TEY) fine-structure measurements. The authors assign the PEY fine structure to the coupling of excited molecular vibrational modes to electronic transitions in NO molecules trapped just below the surface. Oxidation resistance of the boron nitride nanotubes is significantly reduced by low energy ion bombardment, as broken B-N bonds are replaced by N-O bonds involving oxygen present in the surface region. In contrast to the PEY spectra, the bulk sensitive TEY measurements on as-grown samples do not exhibit any fine structure while the ion-bombarded samples show a clear vibronic signature of molecular nitrogen.

  7. Silicon nitride protective coatings for silvered glass mirrors

    DOE Patents [OSTI]

    Tracy, C. Edwin (Golden, CO); Benson, David K. (Golden, CO)

    1988-01-01T23:59:59.000Z

    A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate before metal deposition to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors.

  8. High efficiency III-nitride light-emitting diodes

    DOE Patents [OSTI]

    Crawford, Mary; Koleske, Daniel; Cho, Jaehee; Zhu, Di; Noemaun, Ahmed; Schubert, Martin F; Schubert, E. Fred

    2013-05-28T23:59:59.000Z

    Tailored doping of barrier layers enables balancing of the radiative recombination among the multiple-quantum-wells in III-Nitride light-emitting diodes. This tailored doping enables more symmetric carrier transport and uniform carrier distribution which help to reduce electron leakage and thus reduce the efficiency droop in high-power III-Nitride LEDs. Mitigation of the efficiency droop in III-Nitride LEDs may enable the pervasive market penetration of solid-state-lighting technologies in high-power lighting and illumination.

  9. Silicon nitride protective coatings for silvered glass mirrors

    DOE Patents [OSTI]

    Tracy, C.E.; Benson, D.K.

    1984-07-20T23:59:59.000Z

    A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate prior to metal deposition thereon to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors.

  10. Conductive and robust nitride buffer layers on biaxially textured substrates

    DOE Patents [OSTI]

    Sankar, Sambasivan [Chicago, IL; Goyal, Amit [Knoxville, TN; Barnett, Scott A [Evanston, IL; Kim, Ilwon [Skokie, IL; Kroeger, Donald M [Knoxville, TN

    2009-03-31T23:59:59.000Z

    The present invention relates to epitaxial, electrically conducting and mechanically robust, cubic nitride buffer layers deposited epitaxially on biaxially textured substrates such as metals and alloys. The invention comprises of a biaxially textured substrate with epitaxial layers of nitrides. The invention also discloses a method to form such epitaxial layers using a high rate deposition method as well as without the use of forming gases. The invention further comprises epitaxial layers of oxides on the biaxially textured nitride layer. In some embodiments the article further comprises electromagnetic devices which may have superconducting properties.

  11. September 16-21, 2007 Las Vegas, Nevada Gate recess technology on AlGaN/GaN HFET with InGaN as etch-stop layer

    E-Print Network [OSTI]

    Pala, Nezih

    0 2 V(V) C(pF) Before etching (material) After etching (device) G AlGaN substrate i-GaN DS AlN AlGaN substrate AlN i-GaN AlGaN S G DAlGaNAlGaN InGaNInGaN Standard gate recess InGaN stop layer gate recess InGaNICNS 7 September 16-21, 2007 ­ Las Vegas, Nevada Gate recess technology on AlGaN/GaN HFET with InGaN

  12. Iron-Nitride Alloy Magnets: Transformation Enabled Nitride Magnets Absent Rare Earths (TEN Mare)

    SciTech Connect (OSTI)

    None

    2012-01-01T23:59:59.000Z

    REACT Project: Case Western is developing a highly magnetic iron-nitride alloy to use in the magnets that power electric motors found in EVs and renewable power generators. This would reduce the overall price of the motor by eliminating the expensive imported rare earth minerals typically found in today’s best commercial magnets. The iron-nitride powder is sourced from abundant and inexpensive materials found in the U.S. The ultimate goal of this project is to demonstrate this new magnet system, which contains no rare earths, in a prototype electric motor. This could significantly reduce the amount of greenhouse gases emitted in the U.S. each year by encouraging the use of clean alternatives to oil and coal.

  13. Trade-off between morphology, extended defects, and compositional fluctuation induced carrier localization in high In-content InGaN films

    SciTech Connect (OSTI)

    Ju, James; Loitsch, Bernhard; Stettner, Thomas; Schuster, Fabian; Stutzmann, Martin; Koblmüller, Gregor, E-mail: Gregor.Koblmueller@wsi.tum.de [Walter Schottky Institut and Physik Department, Technische Universität München, Garching 85748 (Germany)

    2014-08-07T23:59:59.000Z

    We elucidate the role of growth parameters (III/N flux ratio, temperature T{sub G}) on the morphological and structural properties, as well as compositional homogeneity and carrier localization effects of high In-content (x(In)?>?0.75) In–polar InGaN films grown by plasma–assisted molecular beam epitaxy (PAMBE). Variations in III/N flux ratio evidence that higher excess of In yields higher threading dislocation densities as well as larger compositional inhomogeneity as measured by x-ray diffraction. Most interestingly, by variation of growth temperature T{sub G} we find a significant trade-off between improved morphological quality and compositional homogeneity at low–T{sub G} (?450–550?°C) versus improved threading dislocation densities at high–T{sub G} (?600–630?°C), as exemplified for InGaN films with x(In)?=?0.9. The enhanced compositional homogeneity mediated by low–T{sub G} growth is confirmed by systematic temperature-dependent photoluminescence (PL) spectroscopy data, such as lower PL peakwidths, >5× higher PL efficiency (less temperature-induced quenching) and a distinctly different temperature-dependent S-shape behavior of the PL peak energy. From these, we find that the carrier localization energy is as low as ?20?meV for low–T{sub G} grown films (T{sub G}?=?550?°C), while it rises to ?70?meV for high–T{sub G} grown films (T{sub G}?=?630?°C) right below the onset of In–N dissociation. These findings point out that for the kinetically limited metal-rich PAMBE growth of high In-content InGaN a III/N flux ratio of ?1 and low-to-intermediate T{sub G} are required to realize optically more efficient materials.

  14. Monolithic integration of InGaN segments emitting in the blue, green, and red spectral range in single ordered nanocolumns

    SciTech Connect (OSTI)

    Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M. A.; Calleja, E. [ISOM and Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)] [ISOM and Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Kong, X.; Trampert, A. [Paul-Drude-Institut fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)] [Paul-Drude-Institut fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2013-05-06T23:59:59.000Z

    This work reports on the selective area growth by plasma-assisted molecular beam epitaxy and characterization of InGaN/GaN nanocolumnar heterostructures. The optimization of the In/Ga and total III/V ratios, as well as the growth temperature, provides control on the emission wavelength, either in the blue, green, or red spectral range. An adequate structure tailoring and monolithic integration in a single nanocolumnar heterostructure of three InGaN portions emitting in the red-green-blue colors lead to white light emission.

  15. Carrier redistribution between different potential sites in semipolar (202{sup ¯}1) InGaN quantum wells studied by near-field photoluminescence

    SciTech Connect (OSTI)

    Marcinkevi?ius, S. [Department of Materials and Nano Physics, KTH Royal Institute of Technology, Electrum 229, 16440 Kista (Sweden); Gelžinyt?, K. [Department of Materials and Nano Physics, KTH Royal Institute of Technology, Electrum 229, 16440 Kista (Sweden); Institute of Applied Research, Vilnius University, Saul?tekio 9-3, 10222 Vilnius (Lithuania); Zhao, Y.; Nakamura, S.; DenBaars, S. P.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)

    2014-09-15T23:59:59.000Z

    Scanning near-field photoluminescence (PL) spectroscopy at different excitation powers was applied to study nanoscale properties of carrier localization and recombination in semipolar (202{sup ¯}1) InGaN quantum wells (QWs) emitting in violet, blue, and green-yellow spectral regions. With increased excitation power, an untypical PL peak energy shift to lower energies was observed. The shift was attributed to carrier density dependent carrier redistribution between nm-scale sites of different potentials. Near-field PL scans showed that in (202{sup ¯}1) QWs the in-plane carrier diffusion is modest, and the recombination properties are uniform, which is advantageous for photonic applications.

  16. NOVEL SALTS OF GRAPHITE AND A BORON NITRIDE SALT

    E-Print Network [OSTI]

    Bartlett, Neil

    2011-01-01T23:59:59.000Z

    ~ i\\f'{y AND DOCUMENTS SECTION NOVEL SALTS OF GRAPHITE ANDA BORON NITRIDE SALT Neil Bartlett, R. N. Biagioni, B. W.privately owned rights. Novel Salts of Graphite and a Boron

  17. argon nitrides: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    crystals of these nitrides are potentially (more) Du, Li 2011-01-01 8 The Argon Dark Matter Experiment HEP - Experiment (arXiv) Summary: The ArDM experiment, a 1 ton liquid argon...

  18. aluminum nitride insulator: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    K-r grown by a modified Bridgman tech- nique,r6 Rollins, Andrew M. 27 Low-voltage organic thin film transistors with hydrophobic aluminum nitride film as gate insulator Materials...

  19. Single-layer graphene on silicon nitride micromembrane resonators

    E-Print Network [OSTI]

    Schmid, Silvan

    Due to their low mass, high quality factor, and good optical properties, silicon nitride (SiN) micromembrane resonators are widely used in force and mass sensing applications, particularly in optomechanics. The metallization ...

  20. Electron transport in the III-V nitride alloys

    SciTech Connect (OSTI)

    Foutz, B.E.; O'Leary, S.K.; Shur, M.S.; Eastman, L.F.

    1999-07-01T23:59:59.000Z

    The authors study electron transport in the alloys of aluminum nitride and gallium nitride and alloys of indium nitride and gallium nitride. In particular, employing Monte Carlo simulations they determine the velocity-field characteristics associated with these alloys for various alloy compositions. They also determine the dependence of the low-field mobility on the alloy composition. They find that while the low-field mobility is a strong function of the alloy composition, the peak and saturation drift velocities exhibit a more mild dependence. Transient electron transport is also considered. They find that the velocity overshoot characteristic is a strong function of the alloy composition. The device implications of these results are discussed.

  1. Growth and control of microscale to nanoscale carbon nitride particles

    SciTech Connect (OSTI)

    Li, H. Y.; Shi, Y. C.; Feng, P. X. [Physics Department, Dong Hua University, Shanghai 200051 (China); University of Puerto Rico, Rio Piedras, San Juan, Puerto Rico 00931 (Puerto Rico) and Physics Department, Dong Hua University, Shanghai 200051 (China)

    2006-10-02T23:59:59.000Z

    Microscale to nanoscale carbon nitride (China) particles are prepared using plasma sputtering deposition techniques. The preferred orientation of nanoscale CN particle distributions is obtained. Particles are examined using scanning electron microscopy (SEM) and Raman scattering spectroscopy. SEM micrographs show that the CN particles are spherical with nearly the same diameters of 2.5 {mu}m prepared without setting bias voltage. The distribution of these particles is random. Setting bias voltage up to 5 kV, plasma sputtering deposition yields several dispersed ring patterns of particle distributions where many small groups of nanoscale particles are observed. Each group of these particles is in a sunflower type of distribution, in which the biggest (85 nm) particle at the center is surrounded by many small sizes (30 nm) of CN particles. Disk type of the particles with a diameter of 10 {mu}m is also observed at different deposition conditions. Typical carbon bands and CN band in the Raman spectra of the samples are identified. The intensity of the bands obviously varies at the different deposition conditions.

  2. Apparatus for the production of boron nitride nanotubes

    SciTech Connect (OSTI)

    Smith, Michael W; Jordan, Kevin

    2014-06-17T23:59:59.000Z

    An apparatus for the large scale production of boron nitride nanotubes comprising; a pressure chamber containing; a continuously fed boron containing target; a source of thermal energy preferably a focused laser beam; a cooled condenser; a source of pressurized nitrogen gas; and a mechanism for extracting boron nitride nanotubes that are condensed on or in the area of the cooled condenser from the pressure chamber.

  3. Multi-length Scale Modeling of Titanium Nitride Coatings

    E-Print Network [OSTI]

    Grujicic, Mica

    Multi-length Scale Modeling of Titanium Nitride Coatings M. Grujicic and S. G. LaiM. Grujicic and S Conservation Circumferential Momentum Conservation Thermal Energy Balance Species Continuity Dependent of Titanium Nitride Surface Species TiCl4(S): NH2(S): TiCl2(S): NH(S): TiCl(S): N(S): Ti (S): N*(S): Ti*(S): N

  4. Process for preparing titanium nitride powder

    DOE Patents [OSTI]

    Bamberger, C.E.

    1988-06-17T23:59:59.000Z

    A process for making titanium nitride powder by reaction of titanium phosphates with sodium cyanide. The process of this invention may comprise mixing one or more phosphates of Ti with a cyanide salt in the absence of oxygen and heating to a temperature sufficient to cause reaction to occur. In the preferred embodiment the ratio of cyanide salt to Ti should be at least 2 which results in the major Ti-containing product being TiN rather than sodium titanium phosphate byproducts. The process is an improvement over prior processes since the byproducts are water soluble salts of sodium which can easily be removed from the preferred TiN product by washing. 2 tabs.

  5. A boron nitride nanotube peapod thermal rectifier

    SciTech Connect (OSTI)

    Loh, G. C., E-mail: jgloh@mtu.edu [Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Baillargeat, D. [CNRS-International-NTU-Thales Research Alliance (CINTRA), 50 Nanyang Drive, Singapore 637553 (Singapore)

    2014-06-28T23:59:59.000Z

    The precise guidance of heat from one specific location to another is paramount in many industrial and commercial applications, including thermal management and thermoelectric generation. One of the cardinal requirements is a preferential conduction of thermal energy, also known as thermal rectification, in the materials. This study introduces a novel nanomaterial for rectifying heat—the boron nitride nanotube peapod thermal rectifier. Classical non-equilibrium molecular dynamics simulations are performed on this nanomaterial, and interestingly, the strength of the rectification phenomenon is dissimilar at different operating temperatures. This is due to the contingence of the thermal flux on the conductance at the localized region around the scatterer, which varies with temperature. The rectification performance of the peapod rectifier is inherently dependent on its asymmetry. Last but not least, the favourable rectifying direction in the nanomaterial is established.

  6. Method for silicon nitride precursor solids recovery

    DOE Patents [OSTI]

    Crosbie, Gary M. (Dearborn, MI); Predmesky, Ronald L. (Livonia, MI); Nicholson, John M. (Wayne, MI)

    1992-12-15T23:59:59.000Z

    Method and apparatus are provided for collecting reaction product solids entrained in a gaseous outflow from a reaction situs, wherein the gaseous outflow includes a condensable vapor. A condensate is formed of the condensable vapor on static mixer surfaces within a static mixer heat exchanger. The entrained reaction product solids are captured in the condensate which can be collected for further processing, such as return to the reaction situs. In production of silicon imide, optionally integrated into a production process for making silicon nitride caramic, wherein reactant feed gas comprising silicon halide and substantially inert carrier gas is reacted with liquid ammonia in a reaction vessel, silicon imide reaction product solids entrained in a gaseous outflow comprising residual carrier gas and vaporized ammonia can be captured by forming a condensate of the ammonia vapor on static mixer surfaces of a static mixer heat exchanger.

  7. Apparatus for silicon nitride precursor solids recovery

    DOE Patents [OSTI]

    Crosbie, Gary M. (Dearborn, MI); Predmesky, Ronald L. (Livonia, MI); Nicholson, John M. (Wayne, MI)

    1995-04-04T23:59:59.000Z

    Method and apparatus are provided for collecting reaction product solids entrained in a gaseous outflow from a reaction situs, wherein the gaseous outflow includes a condensable vapor. A condensate is formed of the condensable vapor on static mixer surfaces within a static mixer heat exchanger. The entrained reaction product solids are captured in the condensate which can be collected for further processing, such as return to the reaction situs. In production of silicon imide, optionally integrated into a production process for making silicon nitride caramic, wherein reactant feed gas comprising silicon halide and substantially inert carrier gas is reacted with liquid ammonia in a reaction vessel, silicon imide reaction product solids entrained in a gaseous outflow comprising residual carrier gas and vaporized ammonia can be captured by forming a condensate of the ammonia vapor on static mixer surfaces of a static mixer heat exchanger.

  8. Indium and impurity incorporation in InGaN films on polar, nonpolar, and semipolar GaN orientations grown by ammonia molecular beam epitaxy

    SciTech Connect (OSTI)

    Browne, David A.; Young, Erin C.; Lang, Jordan R.; Hurni, Christophe A.; Speck, James S. [Materials Department, University of California Santa Barbara, Santa Barbara, California 93106 (United States)

    2012-07-15T23:59:59.000Z

    The effects of NH{sub 3} flow, group III flux, and substrate growth temperature on indium incorporation and surface morphology have been investigated for bulk InGaN films grown by ammonia molecular beam epitaxy. The incorporation of unintentional impurity elements (H, C, O) in InGaN films was studied as a function of growth temperature for growth on polar (0001) GaN on sapphire templates, nonpolar (1010) bulk GaN, and semipolar (1122), (2021) bulk GaN substrates. Enhanced indium incorporation was observed on both (1010) and (2021) surfaces relative to c-plane, while reduced indium incorporation was observed on (1122) for co-loaded conditions. Indium incorporation was observed to increase with decreasing growth temperature for all planes, while being relatively unaffected by the group III flux rates for a 1:1 Ga:In ratio. Indium incorporation was found to increase at the expense of a decreased growth rate for higher ammonia flows; however, smooth surface morphology was consistently observed for growth on semipolar orientations. Increased concentrations of oxygen and hydrogen were observed on semipolar and nonpolar orientations with a clear trend of increased hydrogen incorporation with indium content.

  9. Synthesis of III-V nitride nanowires with controlled structure, morphology, and composition

    E-Print Network [OSTI]

    Crawford, Samuel Curtis

    2014-01-01T23:59:59.000Z

    The III-V nitride materials system offers tunable electronic and optical properties that can be tailored for specific electronic and optoelectronic applications by varying the (In,Ga,Al)N alloy composition. While nitride ...

  10. Comparing directed efficiency of III-nitride nanowire light-emitting diodes

    E-Print Network [OSTI]

    Gradecak, Silvija

    III-nitride-based nanowires are a promising platform for solid-state lighting. III-nitride nanowires that act as natural waveguides to enhance directed extraction have previously been shown to be free of extended defects ...

  11. Feasibility of breeding in hard spectrum boiling water reactors with oxide and nitride fuels

    E-Print Network [OSTI]

    Feng, Bo, Ph. D. Massachusetts Institute of Technology

    2011-01-01T23:59:59.000Z

    This study assesses the neutronic, thermal-hydraulic, and fuel performance aspects of using nitride fuel in place of oxides in Pu-based high conversion light water reactor designs. Using the higher density nitride fuel ...

  12. SUBMILLIMETER OPTICAL PROPERTIES OF HEXAGONAL BORON NITRIDE A. J. Gatesman, R. H. Giles and J. Waldman

    E-Print Network [OSTI]

    Massachusetts at Lowell, University of

    boron nitride was obtained in four grades (A, HP, M, M26) from The Carborundum Co. in Niagara Fall, NY

  13. Synthesis of cubic niobium nitride by reactive diffusion under nitrogen pressure

    SciTech Connect (OSTI)

    Linde, A.V. [Institute of Structural Macrokinetics and Materials Science (ISMAN), Russian Academy of Sciences, Chernogolovka, Moscow 142432 (Russian Federation); Institut Charles Gerhardt Montpellier (ICGM), PMOF-UM2-CNRS, pl. E. Bataillon, 34095 Montpellier Cedex 5 (France); Marin-Ayral, R.-M. [Institut Charles Gerhardt Montpellier (ICGM), PMOF-UM2-CNRS, pl. E. Bataillon, 34095 Montpellier Cedex 5 (France)], E-mail: rose-marie.ayral@univ-montp2.fr; Granier, D.; Bosc-Rouessac, F. [Institut Charles Gerhardt Montpellier (ICGM), PMOF-UM2-CNRS, pl. E. Bataillon, 34095 Montpellier Cedex 5 (France); Grachev, V.V. [Institute of Structural Macrokinetics and Materials Science (ISMAN), Russian Academy of Sciences, Chernogolovka, Moscow 142432 (Russian Federation)

    2009-05-06T23:59:59.000Z

    The synthesis of niobium nitride by reactive diffusion in a furnace at 1395-1475 deg. C and under nitrogen pressure in the range 2-25 MPa was investigated. In experiments, we used compacted Nb powder with a mean particle size of 43 {mu}m. Phase transformations in the product as studied by electron probe microanalysis (EPMA) were found to proceed in the following order: Nb {yields} {alpha}-Nb(N) {yields} {beta}-Nb{sub 2}N{sub 1{+-}}{sub x} {yields} {gamma}-Nb{sub 4}N{sub 3{+-}}{sub x} {yields} {delta}-NbN{sub 1{+-}}{sub x}. The size of niobium particles which could react with nitrogen to yield cubic niobium nitride was estimated (SEM analysis) from the dependence of the thickness {delta} of the {delta}-NbN{sub 1{+-}}{sub x} outer layer formed on the surface of Nb particles on the dwell time t{sub dw} at 1460-1473 deg. C. It was shown that {delta} grew nearly proportional to t{sub dw}. At t{sub dw} = 30 min and P(N{sub 2}) = 2 MPa, {delta} was found to attain a value of about 15.5 {mu}m. Prolonged heating (t{sub dw} {approx} 60 min) was found to result in decomposition of the single-phase cubic niobium nitride into a two-phase (multiphase) product. This was confirmed by XRD data and magnetic measurements which showed the occurrence of two different critical temperatures T{sub c} in the same sample. The maximum critical temperature T{sub c} was found to attain a value of 15.6 K.

  14. OXIDATION MECHANISMS OF LOW ENERGY-HIGH FLUX NITRIDED ODS FeAl INTERMETALLIC ALLOY

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    OXIDATION MECHANISMS OF LOW ENERGY-HIGH FLUX NITRIDED ODS FeAl INTERMETALLIC ALLOY F. Pedraza*, J)5.46.45.72.72 Abstract Microscopy studies of low energy-high flux nitrided ODS FeAl Grade 3 intermetallic alloy reveal nitridation treatment at moderate temperature of ODS FeAl Grade 3 has been performed to modify the surface

  15. Silicon nitride/silicon carbide composite densified materials prepared using composite powders

    DOE Patents [OSTI]

    Dunmead, S.D.; Weimer, A.W.; Carroll, D.F.; Eisman, G.A.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Nilsen, K.J.

    1997-07-01T23:59:59.000Z

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  16. DETERMINING OPTICAL CONSTANTS OF URANIUM NITRIDE THIN FILMS IN THE EXTREME

    E-Print Network [OSTI]

    Hart, Gus

    DETERMINING OPTICAL CONSTANTS OF URANIUM NITRIDE THIN FILMS IN THE EXTREME ULTRAVIOLET (1.6-35 NM deposition and characterization of reactively-sputtered uranium nitride thin films. I also report optical.1 Application 1 1.2 Optical Constants 2 1.3 Project Focus 7 2 Uranium Nitride Thin Films 8 2.1 Sputtering 8 2

  17. Molecular orbital studies of titanium nitride chemical vapor deposition: gas phase b-elimination

    E-Print Network [OSTI]

    Schlegel, H. Bernhard

    Molecular orbital studies of titanium nitride chemical vapor deposition: gas phase b) of titanium nitride can be carried out using TiNR24 and NH3 (R Me or Et). Imido compounds are thought. Ó 2001 Pub- lished by Elsevier Science B.V. 1. Introduction It is well known that titanium nitride

  18. Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Formation,

    E-Print Network [OSTI]

    Schlegel, H. Bernhard

    Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Received June 6, 2000 The chemical vapor deposition (CVD) of titanium nitride can be carried out with TiCl4 Titanium nitride thin films have a variety of proper- ties, such as extreme hardness, high chemical

  19. Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Imido Dimer Formation and

    E-Print Network [OSTI]

    Schlegel, H. Bernhard

    Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Imido Dimer Formation- ization of Ti(NR2)2NH in the chemical vapor deposition (CVD) of titanium nitride films. This study uses lead to the formation of higher oligomers. Introduction Titanium nitride thin films have a number

  20. Half-metallic to insulating behavior of rare-earth nitrides C. M. Aerts,1

    E-Print Network [OSTI]

    Svane, Axel Torstein

    Half-metallic to insulating behavior of rare-earth nitrides C. M. Aerts,1 P. Strange,1 M. Horne,1 W in the literature that rare-earth nitrides may form half-metallic ferromagnets.6­8 This is sur- prising because 30 January 2004 The electronic structure of the rare-earth nitrides is studied systematically using

  1. Europium Nitride: A Novel Diluted Magnetic Semiconductor Do Le Binh,1

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Europium Nitride: A Novel Diluted Magnetic Semiconductor Do Le Binh,1 B. J. Ruck,1,* F. Natali,1 H June 2013; published 18 October 2013) Europium nitride is semiconducting and contains nonmagnetic Eu3þ­24]. Europium nitride has also been demonstrated to be semiconducting [25], but EuN stands out amongst the rare

  2. Anisotropic In distribution in InGaN core-shell nanowires

    SciTech Connect (OSTI)

    Leclere, C.; Renevier, H., E-mail: Hubert.Renevier@grenoble-inp.fr [Laboratoire des Matériaux et du Génie Physique, Grenoble INP - Minatec, Grenoble (France); Katcho, N. A. [Liten, CEA-Grenoble, 17 rue des martyrs, 38054 Grenoble (France); Tourbot, G.; Daudin, B. [CEA-CNRS group Nanophysique et Semiconducteurs, Université Joseph Fourier and CEA Grenoble, INAC, SP2M, 17 rue des Martyrs, 38054 Grenoble (France); Proietti, M. G. [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Aragon, CSIC - Universidad de Zaragoza, Zaragoza (Spain)

    2014-07-07T23:59:59.000Z

    In this work, we investigate the local atomic structure of defect-free homogeneous and self-organized core-shell structure nanowires by means of X-ray Absorption Fine Structure (XAFS) Spectroscopy at the In L{sub III} and K edges and Multiwavelength Anomalous Diffraction. The results are interpreted by comparison of the experimental data with X-ray absorption calculations carried out with ab initio structural models. Extended-XAFS data analysis at In K-edge shows an anisotropic In distribution in the second nearest neighbors pointing out to a deviation from randomness in In distribution for the core-shell sample.

  3. Active Control of Nitride Plasmonic Dispersion in the Far Infrared.

    SciTech Connect (OSTI)

    Shaner, Eric A.; Dyer, Gregory Conrad; Seng, William Francis; Bethke, Donald Thomas; Grine, Albert Dario,; Baca, Albert G.; Allerman, Andrew A.

    2014-11-01T23:59:59.000Z

    We investigate plasmonic structures in nitride-based materials for far-infrared (IR) applications. The two dimensional electron gas (2DEG) in the GaN/AlGaN material system, much like metal- dielectric structures, is a patternable plasmonic medium. However, it also permits for direct tunability via an applied voltage. While there have been proof-of-principle demonstrations of plasma excitations in nitride 2DEGs, exploration of the potential of this material system has thus far been limited. We recently demonstrated coherent phenomena such as the formation of plasmonic crystals, strong coupling of tunable crystal defects to a plasmonic crystal, and electromagnetically induced transparency in GaAs/AlGaAs 2DEGs at sub-THz frequencies. In this project, we explore whether these effects can be realized in nitride 2DEG materials above 1 THz and at temperatures exceeding 77 K.

  4. Characterization of nitrided silicon-silicon dioxide interfaces

    SciTech Connect (OSTI)

    Polignano, M.L.; Alessandri, M.; Brazzelli, D. [and others

    2000-07-01T23:59:59.000Z

    A newly-developed technique for the simultaneous characterization of the oxide-silicon interface properties and of bulk impurities was used for a systematic study of the nitridation process of thin oxides. This technique is based upon surface recombination velocity measurements, and does not require the formation of a capacitor structure, so it is very suitable for the characterization of as-grown interfaces. Oxides grown both in dry and in wet environments were considered, and nitridation processes in N{sub 2}O and in NO were compared to N{sub 2} annealing processes. The effect of nitridation temperature and duration were also studied, and RTO/RTN processes were compared to conventional furnace nitridation processes. Surface recombination velocity was correlated with nitrogen concentration at the oxide-silicon interface obtained by Secondary Ion Mass Spectroscopy (SIMS) measurements. Surface recombination velocity (hence surface state density) decreases with increasing nitrogen pile-up at the oxide-silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are much more effective than N{sub 2}O treatments in the formation of nitrogen-rich interface layer and, as a consequence, in surface state reduction. Surface state density was measured in fully processed wafers before and after constant current stress. After a complete device process surface states are annealed out by hydrogen passivation, however they are reactivated by the electrical stress, and surface state results after stress were compared with data of surface recombination velocity in as-processed wafers.

  5. Electrical properties of TiN on gallium nitride grown using different deposition conditions and annealing

    SciTech Connect (OSTI)

    Li, Liuan; Kishi, Akinori; Shiraishi, Takayuki; Jiang, Ying; Wang, Qingpeng; Ao, Jin-Ping, E-mail: jpao@ee.tokushima-u.ac.jp [Institute of Technology and Science, The University of Tokushima, Tokushima 770-8506 (Japan)

    2014-03-15T23:59:59.000Z

    This study evaluates the thermal stability of different refractory metal nitrides used as Schottky electrodes on GaN. The results demonstrate that TiN, MoSiN, and MoN possess good rectification and adhesion strength, with barrier heights of 0.56, 0.54, and 0.36?eV, respectively. After thermal treatment at 850?°C for 1?min, the TiN and MoN electrodes still exhibit rectifying characteristics, while the MoSiN degrades to an ohmic-like contact. For further study, several TiN films are deposited using different N{sub 2}/Ar reactive/inert sputtering gas ratios, thereby varying the nitrogen content present in the sputtering gas. Ohmic-like contact is observed with the pure Ti contact film, and Schottky characteristics are observed with the samples possessing nitrogen in the film. The average Schottky barrier height is about 0.5?eV and remains virtually constant with varying nitrogen deposition content. After examining Raman spectra and x-ray photoelectron spectroscopy results, the increase in the film resistivity after thermal treatment is attributed to oxidation and/or nitridation. Films deposited with a medium (40% and 60%) nitrogen content show the best film quality and thermal stability.

  6. Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

    SciTech Connect (OSTI)

    Drryl P. Butt; Brian Jaques

    2009-03-31T23:59:59.000Z

    Research conducted for this NERI project has advanced the understanding and feasibility of nitride nuclear fuel processing. In order to perform this research, necessary laboratory infrastructure was developed; including basic facilities and experimental equipment. Notable accomplishments from this project include: the synthesis of uranium, dysprosium, and cerium nitrides using a novel, low-cost mechanical method at room temperature; the synthesis of phase pure UN, DyN, and CeN using thermal methods; and the sintering of UN and (Ux, Dy1-x)N (0.7 ? X ? 1) pellets from phase pure powder that was synthesized in the Advanced Materials Laboratory at Boise State University.

  7. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOE Patents [OSTI]

    Koc, Rasit (Lakewood, CO); Glatzmaier, Gregory C. (Boulder, CO)

    1995-01-01T23:59:59.000Z

    A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  8. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOE Patents [OSTI]

    Koc, R.; Glatzmaier, G.C.

    1995-05-23T23:59:59.000Z

    A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  9. Strong carrier localization and diminished quantum-confined Stark effect in ultra-thin high-indium-content InGaN quantum wells with violet light emission

    SciTech Connect (OSTI)

    Ko, Suk-Min; Kwack, Ho-Sang; Park, Chunghyun; Yoo, Yang-Seok; Cho, Yong-Hoon, E-mail: yhc@kaist.ac.kr [Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)] [Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kwon, Soon-Yong [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of) [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Jin Kim, Hee; Yoon, Euijoon, E-mail: eyoon@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)] [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Si Dang, Le [Nanophysics and Semiconductors, CEA-CNRS-UJF Group, Institut Néel, CNRS Grenoble, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France)] [Nanophysics and Semiconductors, CEA-CNRS-UJF Group, Institut Néel, CNRS Grenoble, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France)

    2013-11-25T23:59:59.000Z

    Here, we report on the optical and structural characteristics of violet-light-emitting, ultra-thin, high-Indium-content (UTHI) InGaN/GaN multiple quantum wells (MQWs), and of conventional low-In-content MQWs, which both emit at similar emission energies though having different well thicknesses and In compositions. The spatial inhomogeneity of In content, and the potential fluctuation in high-efficiency UTHI MQWs were compared to those in the conventional low-In-content MQWs. We conclude that the UTHI InGaN MQWs are a promising structure for achieving better quantum efficiency in the visible and near-ultraviolet spectral range, owing to their strong carrier localization and reduced quantum-confined Stark effect.

  10. Methods for improved growth of group III nitride buffer layers

    DOE Patents [OSTI]

    Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

    2014-07-15T23:59:59.000Z

    Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

  11. Continuous Fiber Ceramic Composite (CFCC) Program: Gaseous Nitridation

    SciTech Connect (OSTI)

    R. Suplinskas G. DiBona; W. Grant

    2001-10-29T23:59:59.000Z

    Textron has developed a mature process for the fabrication of continuous fiber ceramic composite (CFCC) tubes for application in the aluminum processing and casting industry. The major milestones in this project are System Composition; Matrix Formulation; Preform Fabrication; Nitridation; Material Characterization; Component Evaluation

  12. Cubic Lithium Nitride Amy Lazicki1,2

    E-Print Network [OSTI]

    Islam, M. Saif

    Cubic Lithium Nitride to 200 GPa Amy Lazicki1,2 Choong-Shik Yoo1, Warren Pickett2, Richard electrolyte material for lithium-based batteries · possible hydrogen storage material Thrust of this research ­ differences between the XRS and PDOS are indications of the presence of core-hole interactions (excitons

  13. BORON NITRIDE CAPACITORS FOR ADVANCED POWER ELECTRONIC DEVICES

    SciTech Connect (OSTI)

    N. Badi; D. Starikov; C. Boney; A. Bensaoula; D. Johnstone

    2010-11-01T23:59:59.000Z

    This project fabricates long-life boron nitride/boron oxynitride thin film -based capacitors for advanced SiC power electronics with a broad operating temperature range using a physical vapor deposition (PVD) technique. The use of vapor deposition provides for precise control and quality material formation.

  14. Evaluation and silicon nitride internal combustion engine components

    SciTech Connect (OSTI)

    Voldrich, W. (Allied-Signal Aerospace Co., Torrance, CA (United States). Garrett Ceramic Components Div.)

    1992-04-01T23:59:59.000Z

    The feasibility of silicon nitride (Si[sub 3]N[sub 4]) use in internal combustion engines was studied by testing three different components for wear resistance and lower reciprocating mass. The information obtained from these preliminary spin rig and engine tests indicates several design changes are necessary to survive high-stress engine applications. The three silicon nitride components tested were valve spring retainers, tappet rollers, and fuel pump push rod ends. Garrett Ceramic Components' gas-pressure sinterable Si[sub 3]N[sub 4] (GS-44) was used to fabricate the above components. Components were final machined from densified blanks that had been green formed by isostatic pressing of GS-44 granules. Spin rig testing of the valve spring retainers indicated that these Si[sub 3]N[sub 4] components could survive at high RPM levels (9,500) when teamed with silicon nitride valves and lower spring tension than standard titanium components. Silicon nitride tappet rollers showed no wear on roller O.D. or I.D. surfaces, steel axles and lifters; however, due to the uncrowned design of these particular rollers the cam lobes indicated wear after spin rig testing. Fuel pump push rod ends were successful at reducing wear on the cam lobe and rod end when tested on spin rigs and in real-world race applications.

  15. Heterostructures for Increased Quantum Efficiency in Nitride LEDs

    SciTech Connect (OSTI)

    Davis, Robert

    2010-09-30T23:59:59.000Z

    Task 1. Development of an advanced LED simulator useful for the design of efficient nitride-based devices. Simulator will contain graphical interface software that can be used to specify the device structure, the material parameters, the operating conditions and the desired output results. I-4 Task 2. Theoretical and experimental investigations regarding the influence on the microstructure, defect concentration, mechanical stress and strain and IQE of controlled changes in the chemistry and process route of deposition of the buffer layer underlying the active region of nitride-based blue- and greenemitting LEDs. I-9 Task 3. Theoretical and experimental investigations regarding the influence on the physical properties including polarization and IQE of controlled changes in the geometry, chemistry, defect density, and microstructure of components in the active region of nitride-based blue- and green-emitting LEDs. II-37 Task 4. Theoretical and experimental investigations regarding the influence on IQE of novel heterostructure designs to funnel carriers into the active region for enhanced recombination efficiency and elimination of diffusion beyond this region. II-52 Task 5. Theoretical and experimental investigations regarding the influence of enhanced p-type doping on the chemical, electrical, and microstructural characteristics of the acceptor-doped layers, the hole injection levels at Ohmic contacts, the specific contact resistivity and the IQE of nitride-based blue- and green-emitting LEDs. Development and optical and electrical characterization of reflective Ohmic contacts to n- and p-type GaN films. I

  16. Selective area growth and characterization of GaN nanocolumns, with and without an InGaN insertion, on semi-polar (11–22) GaN templates

    SciTech Connect (OSTI)

    Bengoechea-Encabo, A.; Albert, S.; Barbagini, F.; Sanchez-Garcia, M. A.; Calleja, E. [ISOM and Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n 28040 Madrid (Spain)] [ISOM and Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n 28040 Madrid (Spain); Zuñiga-Perez, J.; Mierry, P. de [CRHEA-CNRS, 06560 Valbonne (France)] [CRHEA-CNRS, 06560 Valbonne (France); Trampert, A. [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)] [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2013-12-09T23:59:59.000Z

    The aim of this work is the selective area growth (SAG) of GaN nanocolumns, with and without an InGaN insertion, by molecular beam epitaxyon semi-polar (11–22) GaN templates. The high density of stacking faults present in the template is strongly reduced after SAG. A dominant sharp photoluminescence emission at 3.473 eV points to high quality strain-free material. When embedding an InGaN insertion into the ordered GaN nanostructures, very homogeneous optical properties are observed, with two emissions originating from different regions of each nanostructure, most likely related to different In contents on different crystallographic planes.

  17. Gas source molecular beam epitaxy of scandium nitride on silicon carbide and gallium nitride surfaces

    SciTech Connect (OSTI)

    King, Sean W., E-mail: sean.king@intel.com; Davis, Robert F. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Nemanich, Robert J. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-11-01T23:59:59.000Z

    Scandium nitride (ScN) is a group IIIB transition metal nitride semiconductor with numerous potential applications in electronic and optoelectronic devices due to close lattice matching with gallium nitride (GaN). However, prior investigations of ScN have focused primarily on heteroepitaxial growth on substrates with a high lattice mismatch of 7%–20%. In this study, the authors have investigated ammonia (NH{sub 3}) gas source molecular beam epitaxy (NH{sub 3}-GSMBE) of ScN on more closely lattice matched silicon carbide (SiC) and GaN surfaces (<3% mismatch). Based on a thermodynamic analysis of the ScN phase stability window, NH{sub 3}-GSMBE conditions of 10{sup ?5}–10{sup ?4} Torr NH{sub 3} and 800–1050?°C where selected for initial investigation. In-situ x-ray photoelectron spectroscopy (XPS) and ex-situ Rutherford backscattering measurements showed all ScN films grown using these conditions were stoichiometric. For ScN growth on 3C-SiC (111)-(?3?×??3)R30° carbon rich surfaces, the observed attenuation of the XPS Si 2p and C 1s substrate core levels with increasing ScN thickness indicated growth initiated in a layer-by-layer fashion. This was consistent with scanning electron microscopy (SEM) images of 100–200?nm thick films that revealed featureless surfaces. In contrast, ScN films grown on 3C-SiC (111)-(3?×?3) and 3C-SiC (100)-(3?×?2) silicon rich surfaces were found to exhibit extremely rough surfaces in SEM. ScN films grown on both 3C-SiC (111)-(?3?×??3)R30° and 2H-GaN (0001)-(1?×?1) epilayer surfaces exhibited hexagonal (1?×?1) low energy electron diffraction patterns indicative of (111) oriented ScN. X-ray diffraction ?-2? rocking curve scans for these same films showed a large full width half maximum of 0.29° (1047?arc sec) consistent with transmission electron microscopy images that revealed the films to be poly-crystalline with columnar grains oriented at ?15° to the [0001] direction of the 6H-SiC (0001) substrate. In-situ reflection electron energy loss spectroscopy measurements determined the band-gap for the NH{sub 3}-GSMBE ScN films to be 1.5?±?0.3 eV, and thermal probe measurements indicated all ScN films to be n-type. The four point probe sheet resistance of the ScN films was observed to increase with decreasing growth temperature and decreased with unintentional oxygen incorporation. Hg probe capacitance–voltage measurements indicated N{sub D}-N{sub A} decreased with decreasing growth temperature from 10{sup 19} to 10{sup 20}/cm{sup 3} for the lowest resistivity films to ?5?×?10{sup 16}/cm{sup 3} for the highest resistivity films. In-situ ultraviolet photoelectron spectroscopy measurements additionally showed the valence band maximum moving from 1.4 to 0.8 eV below the Fermi level with decreasing growth temperature consistent with the increased resistivity and reduction in carrier concentration. These results suggest that additional reductions in ScN carrier concentrations can be achieved via continued optimization of ScN growth conditions and selection of substrate orientation and surface termination.

  18. Method and apparatus for use of III-nitride wide bandgap semiconductors in optical communications

    DOE Patents [OSTI]

    Hui, Rongqing (Lenexa, KS); Jiang,Hong-Xing (Manhattan, KS); Lin, Jing-Yu (Manhattan, KS)

    2008-03-18T23:59:59.000Z

    The present disclosure relates to the use of III-nitride wide bandgap semiconductor materials for optical communications. In one embodiment, an optical device includes an optical waveguide device fabricated using a III-nitride semiconductor material. The III-nitride semiconductor material provides for an electrically controllable refractive index. The optical waveguide device provides for high speed optical communications in an infrared wavelength region. In one embodiment, an optical amplifier is provided using optical coatings at the facet ends of a waveguide formed of erbium-doped III-nitride semiconductor materials.

  19. Synthesis and Functionalization of Carbon and Boron Nitride Nanomaterials and Their Applications

    E-Print Network [OSTI]

    Erickson, Kristopher John

    2012-01-01T23:59:59.000Z

    Carbon Nitrides for Hydrogen Storage. Adv. Funct. Mater.N compounds for chemical hydrogen storage. Chemical SocietyT. , High-Pressure Hydrogen Storage in Zeolite-Templated

  20. amorphous carbon-nitride films: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    in hard and elastic amorphous carbon nitride films investigated H NMR spectroscopy Materials Science Websites Summary: Received 14 February 2003; published 5 November 2003 The...

  1. The phase diagram and hardness of carbon nitrides

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dong, Huafeng; Oganov, Artem R.; Zhu, Qiang; Qian, Guang-Rui

    2015-05-06T23:59:59.000Z

    Novel superhard materials, especially those with superior thermal and chemical stability, are needed to replace diamond. Carbon nitrides (C-N), which are likely to possess these characteristics and have even been expected to be harder than diamond, are excellent candidates. Here we report three new superhard and thermodynamically stable carbon nitride phases. Based on a systematic evolutionary structure searches, we report a complete phase diagram of the C-N system at 0–300 GPa and analyze the hardest metastable structures. Surprisingly, we find that at zero pressure, the earlier proposed graphitic-C3N4 structure (P_6m2) is dynamically unstable, and we find the lowest-energy structure based on s-triazine unit and s-heptazine unit.

  2. Development of silicon nitride composites with continuous fiber reinforcement

    SciTech Connect (OSTI)

    Starr, T.L.; Mohr, D.L.; Lackey, W.J.; Hanigofsky, J.A. [Georgia Inst. of Tech., Atlanta, GA (United States). Georgia Technology Research Inst.

    1993-10-01T23:59:59.000Z

    The composites were fabricated using ultrafine Si powders prepared by attritor milling; the powders exhibits full conversion to Si nitride in < 3 h at {le} 1200 C (these conditions reduce degradation of the fibers compared to conventional). Effects of processing conditions on fiber properties and the use of fiber coatings to improve stability during processing as well as change the fiber-matrix interfacial properties were investigated. A duplex carbon-silicon carbide coating, deposited by CVD, reduced fiber degradation in processing, and it modified the fiber-matrix adhesion. Si nitride matrix composites were fabricated using reaction sintering, forming laminates, filament-wound plates, and tubes. In each case, an attritor milled Si powder slurry is infiltrated into ceramic fiber preforms or tows, which are then assembled to form a 3-D structure for reaction sintering. The resulting composites have properties comparable to chemical vapor infiltration densified composites, with reasonable strengths and graceful composite fracture behavior.

  3. Purification of boron nitride nanotubes via polymer wrapping

    SciTech Connect (OSTI)

    Choi, Jin-Hyuk [Department of Nano Science and Technology, Sejong University, 98 Gunja, Gwangjin, Seoul 143-747 (Korea, Republic of); Kim, Jaewoo [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, 1045 Daedukdaero, Daejeon 305-353 (Korea, Republic of); WCI Quantum Beam based Radiation Research Center, Korea Atomic Energy Research Institute, 1045 Daedukdaero, Daejeon 305-353 (Korea, Republic of); Seo, Duckbong [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, 1045 Daedukdaero, Daejeon 305-353 (Korea, Republic of); Seo, Young-Soo, E-mail: ysseo@sejong.ac.kr [Department of Nano Science and Technology, Sejong University, 98 Gunja, Gwangjin, Seoul 143-747 (Korea, Republic of)

    2013-03-15T23:59:59.000Z

    Highlights: ? Surface modification of boron nitride nanotubes using polymeric materials. ? Surface-modified BNNT was purified with a simple dilution-centrifugation step. ? Surface-modified BNNT can be directly used for polymer composite fabrication ? Degree of purification was analyzed by Raman spectroscopy. - Abstract: Boron nitride nanotubes (BNNT) synthesized by a ball milling-annealing were surface-modified using three different types of polymeric materials. Those materials were chosen depending on future applications especially in polymer nanocomposite fabrications. We found that the surface-modified BNNT can be purified with a simple dilution-centrifugation step, which would be suitable for large-scale purification. Degree of purification was monitored by means of the center peak position and FWHM of E{sub 2g} mode of BNNT in Raman spectra. As the purification of BNNT develops, the peak position was up-shifted while FWHM of the peak was narrowed.

  4. The phase diagram and hardness of carbon nitrides

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dong, Huafeng; Oganov, Artem R.; Zhu, Qiang; Qian, Guang-Rui

    2015-05-06T23:59:59.000Z

    Novel superhard materials, especially those with superior thermal and chemical stability, are needed to replace diamond. Carbon nitrides (C-N), which are likely to possess these characteristics and have even been expected to be harder than diamond, are excellent candidates. Here we report three new superhard and thermodynamically stable carbon nitride phases. Based on a systematic evolutionary structure searches, we report a complete phase diagram of the C-N system at 0–300 GPa and analyze the hardest metastable structures. Surprisingly, we find that at zero pressure, the earlier proposed graphitic-C3N4 structure (P_6m2) is dynamically unstable, and we find the lowest-energy structure basedmore »on s-triazine unit and s-heptazine unit.« less

  5. Electrically dependent bandgaps in graphene on hexagonal boron nitride

    SciTech Connect (OSTI)

    Kaplan, D., E-mail: daniel.b.kaplan.civ@mail.mil; Swaminathan, V. [U.S. Army RDECOM-ARDEC, Fuze Precision Armaments and Technology Directorate, Picatinny Arsenal, New Jersey 07806 (United States); Recine, G. [Department of Applied Physics, Polytechnic Institute of New York University, Brooklyn, New York 11201 (United States); Department of Physics and Engineering Physics, Fordham University, Bronx, New York 10458 (United States)

    2014-03-31T23:59:59.000Z

    We present first-principles calculations on the bandgap of graphene on a layer of hexagonal boron nitride in three different stacking configurations. Relative stability of the configurations is identified and bandgap tunability is demonstrated through the application of an external, perpendicularly applied electric field. We carefully examine the bandgap's sensitivity to both magnitude of the applied field as well as separation between the graphene and hexagonal boron nitride layers. Features of the band structure are examined and configuration-dependent relationships between the field and bandgap are revealed and elucidated through the atom-projected density of states. These findings suggest the potential for opening and modulating a bandgap in graphene as high as several hundred meV.

  6. Synthesis of silicon nitride powders in pulsed RF plasmas

    SciTech Connect (OSTI)

    Buss, R.J.; Ho, P. [Sandia National Labs., Albuquerque, NM (United States); Babu, S.V. [Sandia National Labs., Albuquerque, NM (United States)]|[Clarkson Univ., Potsdam, NY (United States). Dept. of Chemical Engineering

    1995-05-01T23:59:59.000Z

    Nanometer size silicon nitride particles are synthesized using a pulsed radio frequency plasma technique. The plasma is modulated with a square-wave on/off cycle of varying period to control size and morphology and to deduce the growth kinetics. In situ laser light scattering and ex situ particle analysis are used to study the nucleation and growth. For SiH{sub 4}/Ar plasmas which nucleate silicon particles, an initial extremely rapid growth phase is followed by a slower growth rate, approaching the rate of thin film deposition on adjacent flat surfaces. In SiH{sub 4}/NH{sub 3} plasmas, silicon nitride particle size can be tightly controlled by adjusting the plasma-on time. The size dispersion of the particles is large and is consistent with a process of continual nucleation during the plasma-on period. The observed polydispersity differs dramatically from that reported from other laboratories.

  7. Use of silicon in liquid sintered silicon nitrides and sialons

    DOE Patents [OSTI]

    Raj, Rishi (Ithaca, NY); Baik, Sunggi (Ithaca, NY)

    1984-12-11T23:59:59.000Z

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

  8. Use of silicon in liquid sintered silicon nitrides and sialons

    DOE Patents [OSTI]

    Raj, R.; Baik, S.

    1984-12-11T23:59:59.000Z

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

  9. Study the gas sensing properties of boron nitride nanosheets

    SciTech Connect (OSTI)

    Sajjad, Muhammad; Feng, Peter, E-mail: p.feng@upr.edu

    2014-01-01T23:59:59.000Z

    Graphical abstract: - Highlights: • We synthesized boron nitride nanosheets (BNNSs) on silicon substrate. • We analyzed gas sensing properties of BNNSs-based gas-sensor device. • CH{sub 4} gas is used to measure gas-sensing properties of the device. • Quick response and recovery time of the device is recorded. • BNNSs showed excellent sensitivity to the working gas. - Abstract: In the present communication, we report on the synthesis of boron nitride nanosheets (BNNSs) and study of their gas sensing properties. BNNSs are synthesized by irradiating pyrolytic hexagonal boron nitride (h-BN) target using CO{sub 2} laser pulses. High resolution transmission electron microscopic measurements (HRTEM) revealed 2-dientional honeycomb crystal lattice structure of BNNSs. HRTEM, electron diffraction, XRD and Raman scattering measurements clearly identified h-BN. Gas sensing properties of synthesized BNNSs were analyzed with prototype gas sensor using methane as working gas. A systematic response curve of the sensor is recorded in each cycle of gas “in” and “out”; suggesting excellent sensitivity and high performance of BNNSs-based gas-sensor.

  10. Nitridation under ammonia of high surface area vanadium aerogels

    SciTech Connect (OSTI)

    Merdrignac-Conanec, Odile [Laboratoire Verres et Ceramiques, UMR CNRS 6512, Institut de Chimie de Rennes, Universite de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex (France)]. E-mail: odile.merdrignac@univ-rennes1.fr; El Badraoui, Khadija [Laboratoire Verres et Ceramiques, UMR CNRS 6512, Institut de Chimie de Rennes, Universite de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex (France); L'Haridon, Paul [Laboratoire Verres et Ceramiques, UMR CNRS 6512, Institut de Chimie de Rennes, Universite de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex (France)

    2005-01-15T23:59:59.000Z

    Vanadium pentoxide gels have been obtained from decavanadic acid prepared by ion exchange on a resin from ammonium metavanadate solution. The progressive removal of water by solvent exchange in supercritical conditions led to the formation of high surface area V{sub 2}O{sub 5}, 1.6H{sub 2}O aerogels. Heat treatment under ammonia has been performed on these aerogels in the 450-900 deg. C temperature range. The oxide precursors and oxynitrides have been characterized by XRD, SEM, TGA, BET. Nitridation leads to divided oxynitride powders in which the fibrous structure of the aerogel is maintained. The use of both very low heating rates and high surface area aerogel precursors allows a higher rate and a lower threshold of nitridation than those reported in previous works. By adjusting the nitridation temperature, it has been possible to prepare oxynitrides with various nitrogen enrichment and vanadium valency states. Whatever the V(O,N) composition, the oxidation of the oxynitrides in air starts between 250 and 300 deg. C. This determines their potential use as chemical gas sensors at a maximum working temperature of 250 deg. C.

  11. Abstract--Titanium nitride (TiN) has been investigated as a material for MEMS hotplate heaters operating at high

    E-Print Network [OSTI]

    Technische Universiteit Delft

    Abstract--Titanium nitride (TiN) has been investigated as a material for MEMS hotplate heaters widely available. A material similar to Ta5Si3 is titanium nitride (TiN). It combines a very high melting TiN Bond pad TiN Figure 1. Schematic cross section of the hotplate. Titanium Nitride for MEMS

  12. TITANIUM NITRIDE COATING AS A MULTIPACTOR SUPPRESSOR Walid Kaabi*, Alessandro Variola (LAL/IN2P3-CNRS, Orsay)

    E-Print Network [OSTI]

    Boyer, Edmond

    TITANIUM NITRIDE COATING AS A MULTIPACTOR SUPPRESSOR Walid Kaabi*, Alessandro Variola (LAL/IN2P3 Emission Yield (SEY). Titanium Nitride is a good candidate for this purpose since its SEY is about 1.5 [2 was made in a previous paper [5]. Ti- TiN transition determination Titanium to titanium nitride transition

  13. In situ X-ray investigation of changing barrier growth temperatures on InGaN single quantum wells in metal-organic vapor phase epitaxy

    SciTech Connect (OSTI)

    Ju, Guangxu, E-mail: g-ju@nuee.nagoya-u.ac.jp; Honda, Yoshio [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Tabuchi, Masao [Synchrotron Radiation Research Centre, Nagoya University, Nagoya, Aichi 464-8603 (Japan); Takeda, Yoshikazu [Synchrotron Radiation Center, Aichi Science and Technology Foundation, Seto, Aichi 489-0965 (Japan); Nagoya Industrial Science Research Institute, Nagoya, Aichi 464-0819 (Japan); Amano, Hiroshi [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Akasaki Research Center, Nagoya University, Aichi 464-8603 (Japan)

    2014-03-07T23:59:59.000Z

    The effects of GaN quantum barriers with changing growth temperatures on the interfacial characteristics of GaN/InGaN single quantum well (SQW) grown on GaN templates by metalorganic vapour phase epitaxy were in situ investigated by X-ray crystal truncation rod (CTR) scattering and X-ray reflectivity measurements at growth temperature using a laboratory level X-ray diffractometer. Comparing the curve-fitting results of X-ray CTR scattering spectra obtained at growth temperature with that at room temperature, the In{sub x}Ga{sub 1-x}N with indium composition less than 0.11 was stabile of the indium distribution at the interface during the whole growth processes. By using several monolayers thickness GaN capping layer to protect the InGaN well layer within temperature-ramping process, the interfacial structure of the GaN/InGaN SQW was drastically improved on the basis of the curve-fitting results of X-ray CTR scattering spectra, and the narrow full width at half-maximum and strong luminous intensity were observed in room temperature photoluminescence spectra.

  14. NITRIDATION EFFECTS ON THE OXIDATION MECHANISMS OF AN ODS FeAl INTERMETALLIC ALLOY

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    NITRIDATION EFFECTS ON THE OXIDATION MECHANISMS OF AN ODS FeAl INTERMETALLIC ALLOY F. Pedraza*, J-mail: fpedraza@univ-lr.fr Abstract An ODS FeAl intermetallic alloy has been nitrided at low-energy high flux of an ODS FeAl alloy have been discussed [13], indicating the formation of AlN and again of -Fe after

  15. Isotope Effect on the Thermal Conductivity of Boron Nitride Nanotubes C. W. Chang,1,5

    E-Print Network [OSTI]

    Zettl, Alex

    been achieved in Si and Ge via isotopic enrichment [7,8], with enriched carbon (diamond) showing that an enhancement of due to isotope enrichment could be large in boron nitride nanotubes [20]. Although previousIsotope Effect on the Thermal Conductivity of Boron Nitride Nanotubes C. W. Chang,1,5 A. M

  16. Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system

    E-Print Network [OSTI]

    with Mn:Ga ratio between 1:1 to 1.5:1 is grown on wurtzite gallium nitride and scandium nitride substrates. Results suggest that for growth on wurtzite GaN, Ga-polar surface promotes quicker interface formation epitaxially on top of wide band-gap Ga-polar wurtzite GaN(0001), with controllable magnetism by adjusting

  17. MOVPE growth of semipolar III-nitride semiconductors on CVD graphene Priti Gupta n

    E-Print Network [OSTI]

    Deshmukh, Mandar M.

    MOVPE growth of semipolar III-nitride semiconductors on CVD graphene Priti Gupta n , A.A. Rahman pressure metalorganic vapor phase epitaxy B1. Graphene B1. Nitrides B2. Semiconducting III­V materials a b on graphene grown by chemical vapour deposition. GaN, AlGaN alloys, and InN layers are grown using an Al

  18. Ultra-thin ohmic contacts for p-type nitride light emitting devices

    DOE Patents [OSTI]

    Raffetto, Mark (Raleigh, NC); Bharathan, Jayesh (Cary, NC); Haberern, Kevin (Cary, NC); Bergmann, Michael (Chapel Hill, NC); Emerson, David (Chapel Hill, NC); Ibbetson, James (Santa Barbara, CA); Li, Ting (Ventura, CA)

    2012-01-03T23:59:59.000Z

    A semiconductor based Light Emitting Device (LED) can include a p-type nitride layer and a metal ohmic contact, on the p-type nitride layer. The metal ohmic contact can have an average thickness of less than about 25 .ANG. and a specific contact resistivity less than about 10.sup.-3 ohm-cm.sup.2.

  19. TITANIUM NITRIDE COATING AS A MULTIPACTOR SUPPRESSOR ON RF COUPLER CERAMIC WINDOWS*

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    TITANIUM NITRIDE COATING AS A MULTIPACTOR SUPPRESSOR ON RF COUPLER CERAMIC WINDOWS* W. Kaabi# , H. The obtained measurements point out how the Nitrogen vacancy on the film can be controlled very well acting a low Secondary Electron Emission Yield (SEY). Titanium Nitride is a good candidate for this purpose

  20. Ab initio studies of magnetic properties of cobalt and tetracobalt nitride Co4N

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Ab initio studies of magnetic properties of cobalt and tetracobalt nitride Co4N S. F. Matara) , A of perovskite structure Co4N nitride have been in- vestigated within density functional theory using both pseudo versus volume show that the ground state is ferromagnetic in both materials. HCP-Co is found to be more

  1. Field emission and current-voltage properties of boron nitride nanotubes

    E-Print Network [OSTI]

    Rubloff, Gary W.

    Field emission and current-voltage properties of boron nitride nanotubes John Cumings*, A. Zettl microscope. Stable currents were measured in a field emission geometry, but in contact the nanotubes Published by Elsevier Ltd. PACS: 79.70. þ q Keywords: A. Boron nitride; B. Nanotubes; C. Field emission

  2. The effect of surface mechanical attrition treatment on low temperature plasma nitriding of an austenitic stainless

    E-Print Network [OSTI]

    Boyer, Edmond

    of an austenitic stainless steel M. Chemkhi1 , D. Retraint1,* , A. Roos1 , C. Garnier1 , L. Waltz2 , C. Demangel3) followed by plasma nitriding on the mechanical properties of a medical grade austenitic stainless steel, nanocrystalline materials, plasma nitriding, austenitic steels 1. Introduction Austenitic stainless steel AISI 316

  3. Hard superconducting nitrides Xiao-Jia Chen*, Viktor V. Struzhkin*, Zhigang Wu*, Maddury Somayazulu

    E-Print Network [OSTI]

    Wu, Zhigang

    Hard superconducting nitrides Xiao-Jia Chen*, Viktor V. Struzhkin*, Zhigang Wu*, Maddury Somayazulu, and hardness of selected superconducting transition-metal nitrides reveals inter- esting correlations among with the neutron scattering data. The cubic -NbN superconducting phase possesses a bulk modulus of 348 GPa

  4. Microwave Nitridation of Sintered Reaction Bonded Silicon Parts for Natural Gas Fueled Diesel Engines

    SciTech Connect (OSTI)

    Edler, J.; Kiggans, J.O.; Suman, A.W.; Tiegs, T.N.

    1999-01-01T23:59:59.000Z

    This cooperative project was a joint development program between Eaton Corporation and Lockheed Martin Energy Research (LMER). Cooperative work was of benefit to both parties. ORNL was able to assess up-scale of the microwave nitridation process using a more intricate-shaped part designed for application in advanced diesel engines. Eaton Corporation mined access to microwave facilities and expertise for the nitridation of SRBSN materials. The broad objective of the CRADA established with Eaton Corporation and ORNL was to develop cost-effective silicon nitride ceramics compared to the current materials available. The following conclusions can be made from the work performed under the CRADA: (1) Demonstrated that the binder burnout step can be incorporated into the SRBSN processing in the microwave furnace. (2) Scale-up of the microwave nitridation process using Eaton Corporation parts showed that the nitridation weight gains were essentially identical to those obtained by conventional heating. (3) Combined nitridation and sintering processes using silicon nitride beads as packing powders results in degradation of the mechanical properties. (4) Gelcasting of silicon nitride materials using Eaton Si mixtures was demonstrated.

  5. Alternated high-and low-pressure nitriding of austenitic stainless steel: Mechanisms and results

    E-Print Network [OSTI]

    Alternated high- and low-pressure nitriding of austenitic stainless steel: Mechanisms and results G a gas mixture of (N2 /H2):(50/50) in pressure, was applied to stainless-steel AISI 304. In the first or plasma nitriding of metal parts, in par- ticular those made of steel and cast iron, is extensively ap

  6. Tunneling characteristics in chemical vapor deposited graphene hexagonal boron nitride graphene junctions

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Tunneling characteristics in chemical vapor deposited graphene ­ hexagonal boron nitride ­ graphene junctions T. Roy1 , L. Liu2 , S. de la Barrera,3 B. Chakrabarti1,4 , Z. R. Hesabi1 , C. A. Joiner1 Abstract: Large area chemical vapor deposited graphene and hexagonal boron nitride was used to fabricate

  7. Brief Communication Ultra fine carbon nitride nanocrystals synthesized by laser ablation

    E-Print Network [OSTI]

    Bristol, University of

    Brief Communication Ultra fine carbon nitride nanocrystals synthesized by laser ablation in liquid form 15 October 2006 Key words: carbon nitride, laser ablation, liquid-solid interface, nanoparticle synthesized at room tem- perature and pressure using the novel technique of pulsed laser ablation

  8. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    DOE Patents [OSTI]

    Brady, Michael P. (Oak Ridge, TN) [Oak Ridge, TN; Yang, Bing (Oak Ridge, TN) [Oak Ridge, TN; Maziasz, Philip J. (Oak Ridge, TN) [Oak Ridge, TN

    2010-11-09T23:59:59.000Z

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  9. Synthesis of silicon nitride particles in pulsed Rf plasmas

    SciTech Connect (OSTI)

    Buss, R.J.; Babu, S.V.

    1995-11-01T23:59:59.000Z

    Silicon nitride (hydrogenated) particles are synthesized using a pulsed 13.56 Mhz glow discharge. The plasma is modulated with a square-wave on/off cycle of varying period to study the growth kinetics. In situ laser light scattering and ex situ particle analysis are used to study the nucleation and growth. For SiH{sub 4}/Ar and SiH{sub 4}/NH{sub 3} plasmas, an initial very rapid growth phase is followed by slower growth, approaching the rate of thin film deposition on adjacent flat surfaces. The average particle size can be controlled in the 10-100 nm range by adjusting the plasma-on time. The size dispersion of the particles is large and is consistent with a process of continuous nucleation during the plasma-on period. The large polydispersity is also reported for silicon particles from silane and differs from that reported in other laboratories. The silicon nitride particle morphology is compared to that of silicon and silicon carbide particles generated by the same technique. Whereas Si particles appear as rough clusters of smaller subunits, the SiC particles are smooth spheres, and the Si{sub 3}N{sub 4} particles are smooth but non-spherical. Post-plasma oxidation kinetics of the particles are studied with FTIR and are consistent with a hydrolysis mechanism proposed in earlier work with continuous plasmas. Heat treatment of the powder in an ammonia atmosphere results in the elimination of hydrogen, rendering the silicon nitride resistant to atmospheric oxidation.

  10. Synthesis of silicon nitride particles in pulsed radio frequency plasmas

    SciTech Connect (OSTI)

    Buss, R.J. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0367 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-0367 (United States); Babu, S.V. [Department of Chemical Engineering, Clarkson University, Potsdam, New York 13699-5705 (United States)] [Department of Chemical Engineering, Clarkson University, Potsdam, New York 13699-5705 (United States)

    1996-03-01T23:59:59.000Z

    Silicon nitride (hydrogenated) particles are synthesized using a pulsed 13.56 MHz glow discharge. The plasma is modulated with a square-wave on/off cycle of varying period to study the growth kinetics. {ital In} {ital situ} laser light scattering and {ital ex} {ital situ} particle analysis are used to study the nucleation and growth. For SiH{sub 4}/Ar and SiH{sub 4}/NH{sub 3} plasmas, an initial very rapid growth phase is followed by slower growth, approaching the rate of thin film deposition on adjacent flat surfaces. The average particle size can be controlled in the 10{endash}100 nm range by adjusting the plasma-on time. The size dispersion of the particles is large and is consistent with a process of continuous nucleation during the plasma-on period. The large polydispersity is also reported for silicon particles from silane and differs from that reported in other laboratories. The silicon nitride particle morphology is compared to that of silicon and silicon carbide particles generated by the same technique. Whereas Si particles appear as rough clusters of smaller subunits, the SiC particles are smooth spheres, and the Si{sub 3}N{sub 4} particles are smooth but nonspherical. Postplasma oxidation kinetics of the particles are studied with Fourier transform infrared spectra and are consistent with a hydrolysis mechanism proposed in earlier work with continuous plasmas. Heat treatment of the powder in an ammonia atmosphere results in the elimination of hydrogen, rendering the silicon nitride resistant to atmospheric oxidation. {copyright} {ital 1996 American Vacuum Society}

  11. Boron nitride nanosheets as oxygen-atom corrosion protective coatings

    SciTech Connect (OSTI)

    Yi, Min [Beijing Key Laboratory for Powder Technology Research and Development, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Plasma Laboratory, Ministry-of-Education Key Laboratory of Fluid Mechanics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Shen, Zhigang, E-mail: shenzhg@buaa.edu.cn [Beijing Key Laboratory for Powder Technology Research and Development, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Plasma Laboratory, Ministry-of-Education Key Laboratory of Fluid Mechanics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); School of Material Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Zhao, Xiaohu [Plasma Laboratory, Ministry-of-Education Key Laboratory of Fluid Mechanics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Liang, Shuaishuai [Beijing Key Laboratory for Powder Technology Research and Development, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Liu, Lei [Beijing Key Laboratory for Powder Technology Research and Development, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); School of Material Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

    2014-04-07T23:59:59.000Z

    The research of two-dimensional nanomaterials for anticorrosion applications is just recently burgeoning. Herein, we demonstrate the boron nitride nanosheets (BNNSs) coatings for protecting polymer from oxygen-atom corrosion. High-quality BNNSs, which are produced by an effective fluid dynamics method with multiple exfoliation mechanisms, can be assembled into coatings with controlled thickness by vacuum filtration. After exposed in atom oxygen, the naked polymer is severely corroded with remarkable mass loss, while the BNNSs-coated polymer remains intact. Barrier and bonding effects of the BNNSs are responsible for the coating's protective performance. These preliminary yet reproducible results pave a way for resisting oxygen-atom corrosion.

  12. Field emission characteristics from graphene on hexagonal boron nitride

    SciTech Connect (OSTI)

    Yamada, Takatoshi, E-mail: takatoshi-yamada@aist.go.jp [National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Masuzawa, Tomoaki; Ebisudani, Taishi; Okano, Ken [International Christian University, 3-10-2 Osawa, Mitaka, Tokyo 181-8585 (Japan); Taniguchi, Takashi [National Institute for Material Science (NIMS), 1-1-1 Namiki, Tsukuba 305-0044 (Japan)

    2014-06-02T23:59:59.000Z

    An attempt has been made to utilize uniquely high electron mobility of graphene on hexagonal boron nitride (h-BN) to electron emitter. The field emission property of graphene/h-BN/Si structure has shown enhanced threshold voltage and emission current, both of which are key to develop novel vacuum nanoelectronics devices. The field emission property was discussed along with the electronic structure of graphene investigated by Fowler-Nordheim plot and ultraviolet photoelectron spectroscopy. The result suggested that transferring graphene on h-BN modified its work function, which changed field emission mechanism. Our report opens up a possibility of graphene-based vacuum nanoelectronics devices with tuned work function.

  13. Method of nitriding niobium to form a superconducting surface

    DOE Patents [OSTI]

    Kelley, Michael J.; Klopf, John Michael; Singaravelu, Senthilaraja

    2014-08-19T23:59:59.000Z

    A method of forming a delta niobium nitride .delta.-NbN layer on the surface of a niobium object including cleaning the surface of the niobium object; providing a treatment chamber; placing the niobium object in the treatment chamber; evacuating the chamber; passing pure nitrogen into the treatment chamber; focusing a laser spot on the niobium object; delivering laser fluences at the laser spot until the surface of the niobium object reaches above its boiling temperature; and rastering the laser spot over the surface of the niobium object.

  14. Process for growing epitaxial gallium nitride and composite wafers

    DOE Patents [OSTI]

    Weber, Eicke R.; Subramanya, Sudhir G.; Kim, Yihwan; Kruger, Joachim

    2003-05-13T23:59:59.000Z

    A novel growth procedure to grow epitaxial Group III metal nitride thin films on lattice-mismatched substrates is proposed. Demonstrated are the quality improvement of epitaxial GaN layers using a pure metallic Ga buffer layer on c-plane sapphire substrate. X-ray rocking curve results indicate that the layers had excellent structural properties. The electron Hall mobility increases to an outstandingly high value of .mu.>400 cm.sup.2 /Vs for an electron background concentration of 4.times.10.sup.17 cm.sup.-3.

  15. Glow-discharge synthesis of silicon nitride precursor powders

    SciTech Connect (OSTI)

    Ho, P.; Buss, R.J.; Loehman, R.E. (Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 (US))

    1989-07-01T23:59:59.000Z

    A radio-frequency glow discharge is used for the synthesis of submicron, amorphous, silicon nitride precursor powders from silane and ammonia. Powders are produced with a range of Si/N ratios, including stoichiometric, Si-rich, and N-rich, and contain substantial amounts of hydrogen. The powders appear to be similar to silicon diimide and are easily converted to oxide by water vapor. The powders lose weight and crystallize to a mixture of {alpha} and {beta}-Si{sub 3}N{sub 4} after prolonged heating at 1600{degree}C. Studies of spectrally and spatially resolved optical emission from the plasma are reported.

  16. Sampling box

    DOE Patents [OSTI]

    Phillips, Terrance D. (617 Chestnut Ct., Aiken, SC 29803); Johnson, Craig (100 Midland Rd., Oak Ridge, TN 37831-0895)

    2000-01-01T23:59:59.000Z

    An air sampling box that uses a slidable filter tray and a removable filter cartridge to allow for the easy replacement of a filter which catches radioactive particles is disclosed.

  17. Radiation tolerance of piezoelectric bulk single-crystal aluminum nitride

    SciTech Connect (OSTI)

    David A. Parks; Bernhard R. Tittmann

    2014-07-01T23:59:59.000Z

    For practical use in harsh radiation environments, we pose selection criteria for piezoelectric materials for nondestructive evaluation (NDE) and material characterization. Using these criteria, piezoelectric aluminum nitride is shown to be an excellent candidate. The results of tests on an aluminumnitride-based transducer operating in a nuclear reactor are also presented. We demonstrate the tolerance of single-crystal piezoelectric aluminum nitride after fast and thermal neutron fluences of 1.85 × 1018 neutron/cm2 and 5.8 × 1018 neutron/cm2, respectively, and a gamma dose of 26.8 MGy. The radiation hardness of AlN is most evident from the unaltered piezoelectric coefficient d33, which measured 5.5 pC/N after a fast and thermal neutron exposure in a nuclear reactor core for over 120 MWh, in agreement with the published literature value. The results offer potential for improving reactor safety and furthering the understanding of radiation effects on materials by enabling structural health monitoring and NDE in spite of the high levels of radiation and high temperatures, which are known to destroy typical commercial ultrasonic transducers.

  18. Nitride and Oxynitride Based Phosphors for Solid State Lighting

    SciTech Connect (OSTI)

    Tian, Yongchi

    2011-10-15T23:59:59.000Z

    The objective of the project is to advance the technology of the Lightscape Materials Inc. (Lightscape) proprietary nitride and oxynitride phosphors for solid state lighting (SSL) from the current level of maturity of applied research to advanced engineering development. This objective will be accomplished by optimizing the novel nitride and oxynitride phosphors, whose formulations are listed in Table 1, and establishing cost-effective preparation processes for the phosphors. The target performances of the phosphors are: • High luminescence efficiency: Quantum Yield = 90%. • Superior thermal stability of luminescence: Thermal Quenching Loss <10% at 150 °C. • Superior environmental stability: Luminescence Maintenance >90% after 5,000 hours at 85 °C and 85% relative humidity. • Scattering loss <10%. • Cost-effective preparation processes. The resulting phosphor materials and their preparation processes are anticipated to be a drop-in component for product development paths undertaken by LED lamp makers in the SSL industry. Upon program completion, Lightscape will target market insertion that enables high efficacy, high color rendering index (CRI), high thermal stability and long lifetime LED-based lighting products for general illumination that realizes substantial energy savings.

  19. High upper critical field in disordered niobium nitride superconductor

    SciTech Connect (OSTI)

    Baskaran, R., E-mail: baskaran@igcar.gov.in; Thanikai Arasu, A. V.; Amaladass, E. P.; Janawadkar, M. P. [Materials Science Group, IGCAR, Kalpakkam-603102 (India)

    2014-10-28T23:59:59.000Z

    Superconducting Niobium Nitride thin films have been deposited on glass, aluminum nitride buffered glass, and oxidized silicon substrates by reactive DC magnetron sputtering at ambient substrate temperatures. The crystal structure of these thin films has been determined to be cubic fcc B1 structure by Glancing Incidence X-Ray Diffraction analysis. The superconducting transition temperatures of the thin films were measured to be greater than 11.6?K with a maximum of 13.4?K. The negative temperature coefficient of resistance observed in these thin films indicates the presence of disorder. Magneto-resistance measurements have been carried out on these thin films patterned into standard four probe geometry upto a maximum magnetic field of 12?T for two films and upto 15?T for the other two films. The dependence of transition temperature on the applied field is analyzed to estimate the upper critical field. The upper critical field for most of the films was estimated to exceed 35?T, while one of the most disordered films had an estimated upper critical field greater than 70?T.

  20. Gallium nitride microcavities formed by photoenhanced wet oxidation

    SciTech Connect (OSTI)

    Peng, L.-H.; Lu, C.-Y.; Wu, W.-H.; Wang, S.-L. [Department of Electrical Engineering and Institute of Electro-Optical Engineering, National Taiwan University, Taipei, Taiwan (China)

    2005-10-17T23:59:59.000Z

    We report the formation of gallium nitride (GaN) microcavities by manipulating a photoenhanced oxidation rate difference between the polar and nonpolar crystallographic planes of GaN. When immersed in a buffered acetic (CH{sub 3}COOH) electrolyte of pH{approx}6.2 at room temperature, it is shown that the photo-oxidation can proceed at a rate that is one order of magnitude slower on the nonpolar plane of {l_brace}1100{r_brace}{sub GaN} than on the polar plane of {l_brace}0001{r_brace}{sub GaN} due to the reduced surface field action. Gallium nitride microcavities bounded by optically smooth {l_brace}1100{r_brace} and {l_brace}1103{r_brace} facets can thus be preferentially formed on the c-plane sapphire substrate after dissolving the oxide layer. The optical properties of these GaN hexagonal cavities reveal characteristic peaks of whispering gallery modes in resonance with the GaN band edge emission spectrum. A typical cavity Q factor of 10{sup 3} is observed in these GaN microcavities due to a reduced optical scattering loss in the wet chemical reaction process.

  1. Tunneling characteristics in chemical vapor deposited graphene–hexagonal boron nitride–graphene junctions

    SciTech Connect (OSTI)

    Roy, T.; Hesabi, Z. R.; Joiner, C. A.; Vogel, E. M. [School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, Georgia 30332 (United States); Liu, L.; Gu, G. [Department of Electrical Engineering and Computer Science, University of Tennessee, 1520 Middle Drive, Knoxville, Tennessee 37996 (United States); Barrera, S. de la; Feenstra, R. M. [Department of Physics, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213 (United States); Chakrabarti, B. [School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, Georgia 30332 (United States); Department of Materials Science and Engineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080 (United States)

    2014-03-24T23:59:59.000Z

    Large area chemical vapor deposited graphene and hexagonal boron nitride was used to fabricate graphene–hexagonal boron nitride–graphene symmetric field effect transistors. Gate control of the tunneling characteristics is observed similar to previously reported results for exfoliated graphene–hexagonal boron nitride–graphene devices. Density-of-states features are observed in the tunneling characteristics of the devices, although without large resonant peaks that would arise from lateral momentum conservation. The lack of distinct resonant behavior is attributed to disorder in the devices, and a possible source of the disorder is discussed.

  2. Low Temperature Chemical Vapor Deposition of Zirconium Nitride in a Fluidized Bed 

    E-Print Network [OSTI]

    Arrieta, Marie

    2012-10-19T23:59:59.000Z

    The objective of this research was to design, assemble, and demonstrate the initial performance of a fluidized bed chemical vapor deposition (FB-CVD) system capable of producing thin, uniform zirconium nitride (ZrN) coatings (1 to 10 micrometers...

  3. Assessment of uranium-free nitride fuels for spent fuel transmutation in fast reactor systems 

    E-Print Network [OSTI]

    Szakaly, Frank Joseph

    2004-09-30T23:59:59.000Z

    The purpose of this work is to investigate the implementation of nitride fuels containing little or no uranium in a fast-spectrum nuclear reactor to reduce the amount of plutonium and minor actinides in spent nuclear fuel ...

  4. Method of nitriding, carburizing, or oxidizing refractory metal articles using microwaves

    DOE Patents [OSTI]

    Holcombe, Cressie E. (Knoxville, TN); Dykes, Norman L. (Oak Ridge, TN); Tiegs, Terry N. (Lenoir City, TN)

    1992-01-01T23:59:59.000Z

    A method of nitriding an article of refractory-nitride-forming metal or metalloids. A consolidated metal or metalloid article is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid to an article of refractory nitride. in addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating.

  5. Process for preparing transition metal nitrides and transition metal carbonitrides and their reaction intermediates

    DOE Patents [OSTI]

    Maya, Leon (Oak Ridge, TN)

    1988-05-24T23:59:59.000Z

    A process for making ammonolytic precursors to nitride and carbonitride ceramics. Extreme reaction conditions are not required and the precursor is a powder-like substance that produces ceramics of improved purity and morphology upon pyrolysis.

  6. Precursors in the preparation of transition metal nitrides and transition metal carbonitrides and their reaction intermediates

    DOE Patents [OSTI]

    Maya, Leon (Oak Ridge, TN)

    1991-01-01T23:59:59.000Z

    A process for making ammonolytic precursors to nitride and carbonitride ceramics. Extreme reaction conditions are not required and the precursor is a powder-like substance that produces ceramics of improved purity and morphology upon pyrolysis.

  7. Photon-induced tunneling in graphene-boron nitride-graphene heterostructures

    E-Print Network [OSTI]

    Nair, Nityan

    2013-01-01T23:59:59.000Z

    Graphene is a material that has generated much interest due to its many unique electronic and optical properties. In this work, we present optoelectronic measurements performed on ultrathin graphene-boron nitride-graphene ...

  8. Electronic structure analyses and activation studies of a dinitrogen-derived terminal nitride of molybdenum

    E-Print Network [OSTI]

    Sceats, Emma Louise, 1978-

    2004-01-01T23:59:59.000Z

    Chapter 1: Complexes obtained by electrophilic attack on a dinitrogen-derived terminal molybdenum nitride: Electronic structure analysis by solid state CP/MAS ¹?N NMR in combination ... Chapter 2. Carbene chemistry in the ...

  9. Thermal stability of -titanium in contact with titanium nitride Shi-Qing Wang

    E-Print Network [OSTI]

    Allen, Leslie H.

    Thermal stability of -titanium in contact with titanium nitride Shi-Qing Wang SEMATECH, 2706 microscopy. It was found that nitrogen dissolves from TiN into Ti between 405 and 474 °C and a significant

  10. Aluminum nitride transitional layer for reducing dislocation density and cracking of AIGan epitaxial films

    DOE Patents [OSTI]

    Allerman, Andrew A. (Tijeras, NM); Crawford, Mary H. (Albuquerque, NM); Koleske, Daniel D. (Albuquerque, NM); Lee, Stephen R. (Albuquerque, NM)

    2011-03-29T23:59:59.000Z

    A denticulated Group III nitride structure that is useful for growing Al.sub.xGa.sub.1-xN to greater thicknesses without cracking and with a greatly reduced threading dislocation (TD) density.

  11. Luminescence dynamics and waveguide applications of europium doped gallium nitride powder

    E-Print Network [OSTI]

    Lipson, Michal

    Luminescence dynamics and waveguide applications of europium doped gallium nitride powder Carl B, bismuth shot, and europium ingot in an ammonia ambient to initially obtain chunks of the desired material

  12. In situ formation of tin nanocrystals embedded in silicon nitride matrix

    SciTech Connect (OSTI)

    Huang Shujuan; So, Yong Heng; Conibeer, Gavin; Green, Martin A. [ARC Photovoltaics Centre of Excellence, University of New South Wales, Sydney, New South Wales 2052 (Australia)

    2009-06-15T23:59:59.000Z

    Tin (Sn) nanocrystals (NCs) embedded in a silicon nitride (Si{sub 3}N{sub 4}) matrix have been fabricated in a cosputtering process employing low temperature (100 deg. C) substrate heating. Transmission electron microscopy (TEM) showed the formation of uniformly sized Sn NCs of 5.2+-0.9 nm evenly distributed in the Si{sub 3}N{sub 4} matrix. Both TEM and x-ray diffraction measurements showed that the Sn NCs adopted the semimetallic tetragonal beta-Sn structure rather than the cubic semiconducting alpha-Sn structure. X-ray photoelectron spectroscopy revealed that the semimetallic state (Sn{sup 0}) is the major component of Sn in the sample films. Our investigation demonstrates a pronounced effect of the substrate temperature on the formation of Sn NCs. The mechanism of in situ formation of Sn NCs is discussed. We suggest that the formation of uniformly sized Sn NCs is correlated with lowering the surface mobility of the nuclei due to the presence of the cosputtered Si{sub 3}N{sub 4}.

  13. Synthesis of copper nitride films doped with Fe, Co, or Ni by reactive magnetron sputtering

    SciTech Connect (OSTI)

    Yang, Jianbo [School of Optoelectronics Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Huang, Saijia; Wang, Zhijiao; Hou, Yuxuan; Shi, Yuyu; Zhang, Jian; Yang, Jianping, E-mail: yangjp@njupt.edu.cn; Li, Xing'ao, E-mail: lxahbmy@126.com [School of Materials Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China)

    2014-09-01T23:59:59.000Z

    Copper nitride (Cu{sub 3}N) and Fe-, Co-, and Ni-doped Cu{sub 3}N films were prepared by reactive magnetron sputtering. The films were deposited on silicon substrates at room temperature using pure Cu target and metal chips. The molar ratio of Cu to N atoms in the as-prepared Cu{sub 3}N film was 2.7:1, which is comparable with the stoichiometry ratio 3:1. X-ray diffraction measurements showed that the films were composed of Cu{sub 3}N crystallites with anti-ReO{sub 3} structure and adopted different preferred orientations. The reflectance of the four samples decreased in the wavelength range of 400–830?nm, but increased rapidly within wavelength range of 830–1200?nm. Compared with the Cu{sub 3}N films, the resistivity of the doped Cu{sub 3}N films decreased by three orders of magnitude. These changes have great application potential in optical and electrical devices based on Cu{sub 3}N films.

  14. Impurity-induced disorder in III-nitride materials and devices

    DOE Patents [OSTI]

    Wierer, Jr., Jonathan J; Allerman, Andrew A

    2014-11-25T23:59:59.000Z

    A method for impurity-induced disordering in III-nitride materials comprises growing a III-nitride heterostructure at a growth temperature and doping the heterostructure layers with a dopant during or after the growth of the heterostructure and post-growth annealing of the heterostructure. The post-growth annealing temperature can be sufficiently high to induce disorder of the heterostructure layer interfaces.

  15. Hafnium nitride buffer layers for growth of GaN on silicon

    DOE Patents [OSTI]

    Armitage, Robert D.; Weber, Eicke R.

    2005-08-16T23:59:59.000Z

    Gallium nitride is grown by plasma-assisted molecular-beam epitaxy on (111) and (001) silicon substrates using hafnium nitride buffer layers. Wurtzite GaN epitaxial layers are obtained on both the (111) and (001) HfN/Si surfaces, with crack-free thickness up to 1.2 {character pullout}m. However, growth on the (001) surface results in nearly stress-free films, suggesting that much thicker crack-free layers could be obtained.

  16. Enhanced thermoelectric properties in hybrid graphene-boron nitride nanoribbons

    E-Print Network [OSTI]

    Kaike Yang; Yuanping Chen; Roberto D'Agosta; Yuee Xie; Jianxin Zhong; Angel Rubio

    2012-04-06T23:59:59.000Z

    The thermoelectric properties of hybrid graphene-boron nitride nanoribbons (BCNNRs) are investigated using the non-equilibrium Green's function (NEGF) approach. We find that the thermoelectric figure of merit (ZT) can be remarkably enhanced by periodically embedding hexagonal BN (h-BN) into graphene nanoribbons (GNRs). Compared to pristine GNRs, the ZT for armchair-edged BCNNRs with width index 3p+2 is enhanced up to 10~20 times while the ZT of nanoribbons with other widths is enhanced just by 1.5~3 times. As for zigzag-edge nanoribbons, the ZT is enhanced up to 2~3 times. This improvement comes from the combined increase in the Seebeck coefficient and the reduction in the thermal conductivity outweighing the decrease in the electrical conductance. In addition, the effect of component ratio of h-BN on the thermoelectric transport properties is discussed. These results qualify BCNNRs as a promising candidate for building outstanding thermoelectric devices.

  17. Role of defects in III-nitride based electronics

    SciTech Connect (OSTI)

    HAN,JUNG; MYERS JR.,SAMUEL M.; FOLLSTAEDT,DAVID M.; WRIGHT,ALAN F.; CRAWFORD,MARY H.; LEE,STEPHEN R.; SEAGER,CARLETON H.; SHUL,RANDY J.; BACA,ALBERT G.

    2000-01-01T23:59:59.000Z

    The LDRD entitled ``Role of Defects in III-Nitride Based Devices'' is aimed to place Sandia National Laboratory at the forefront of the field of GaN materials and devices by establishing a scientific foundation in areas such as material growth, defect characterization/modeling, and processing (metalization and etching) chemistry. In this SAND report the authors summarize their studies such as (1) the MOCVD growth and doping of GaN and AlGaN, (2) the characterization and modeling of hydrogen in GaN, including its bonding, diffusion, and activation behaviors, (3) the calculation of energetic of various defects including planar stacking faults, threading dislocations, and point defects in GaN, and (4) dry etching (plasma etching) of GaN (n- and p-types) and AlGaN. The result of the first AlGaN/GaN heterojunction bipolar transistor is also presented.

  18. Enhanced thermoelectric properties in hybrid graphene-boron nitride nanoribbons

    E-Print Network [OSTI]

    Yang, Kaike; D'Agosta, Roberto; Xie, Yuee; Zhong, Jianxin; Rubio, Angel

    2012-01-01T23:59:59.000Z

    The thermoelectric properties of hybrid graphene-boron nitride nanoribbons (BCNNRs) are investigated using the non-equilibrium Green's function (NEGF) approach. We find that the thermoelectric figure of merit (ZT) can be remarkably enhanced by periodically embedding hexagonal BN (h-BN) into graphene nanoribbons (GNRs). Compared to pristine GNRs, the ZT for armchair-edged BCNNRs with width index 3p+2 is enhanced up to 10~20 times while the ZT of nanoribbons with other widths is enhanced just by 1.5~3 times. As for zigzag-edge nanoribbons, the ZT is enhanced up to 2~3 times. This improvement comes from the combined increase in the Seebeck coefficient and the reduction in the thermal conductivity outweighing the decrease in the electrical conductance. In addition, the effect of component ratio of h-BN on the thermoelectric transport properties is discussed. These results qualify BCNNRs as a promising candidate for building outstanding thermoelectric devices.

  19. High-Q terahertz metamaterial from superconducting niobium nitride films

    E-Print Network [OSTI]

    Zhang, C H; Jin, B B; Ji, Z M; Kang, L; Xu, W W; Chen, J; Wu, P H

    2011-01-01T23:59:59.000Z

    We present in this letter terahertz (THz) metamaterials with low ohmic losses made from low-temperature superconductor niobium nitride (NbN) films. The resonance properties are characterized by THz time-domain spectroscopy. The unloaded quality factor reaches as high as about 178 at 8 K with the resonance frequency at around 0.58 THz, which is about 24 times as many as gold metamaterials with the same structure. The unloaded quality factor also keeps high as the resonance frequency increases, which is about 90 at 1.02 THz that is close the gap frequency of NbN film. All these experimental observations are well understood in the framework of Bardeen-Cooper-Schrieffer theory and equivalent circuit model. Our work offers an efficient way to design and make high-performance THz electronic devices.

  20. High-Efficiency Nitride-Based Photonic Crystal Light Sources

    Broader source: Energy.gov [DOE]

    The University of California Santa Barbara (UCSB) is maximizing the efficiency of a white LED by enhancing the external quantum efficiency using photonic crystals to extract light that would normally be confined in a conventional structure. Ultimate efficiency can only be achieved by looking at the internal structure of light. To do this, UCSB is focusing on maximizing the light extraction efficiency and total light output from light engines driven by Gallium Nitride (GaN)-based LEDs. The challenge is to engineer large overlap (interaction) between modes and photonic crystals. The project is focused on achieving high extraction efficiency in LEDs, controlled directionality of emitted light, integrated design of vertical device structure, and nanoscale patterning of lateral structure.

  1. High temperature mechanical performance of a hot isostatically pressed silicon nitride

    SciTech Connect (OSTI)

    Wereszczak, A.A.; Ferber, M.K.; Jenkins, M.G.; Lin, C.K.J. [and others] [and others

    1996-01-01T23:59:59.000Z

    Silicon nitride ceramics are an attractive material of choice for designers and manufacturers of advanced gas turbine engine components for many reasons. These materials typically have potentially high temperatures of usefulness (up to 1400{degrees}C), are chemically inert, have a relatively low specific gravity (important for inertial effects), and are good thermal conductors (i.e., resistant to thermal shock). In order for manufacturers to take advantage of these inherent properties of silicon nitride, the high-temperature mechanical performance of the material must first be characterized. The mechanical response of silicon nitride to static, dynamic, and cyclic conditions at elevated temperatures, along with reliable and representative data, is critical information that gas turbine engine designers and manufacturers require for the confident insertion of silicon nitride components into gas turbine engines. This final report describes the high-temperature mechanical characterization and analyses that were conducted on a candidate structural silicon nitride ceramic. The high-temperature strength, static fatigue (creep rupture), and dynamic and cyclic fatigue performance were characterized. The efforts put forth were part of Work Breakdown Structure Subelement 3.2.1, {open_quotes}Rotor Data Base Generation.{close_quotes} PY6 is comparable to other hot isostatically pressed (HIPed) silicon nitrides currently being considered for advanced gas turbine engine applications.

  2. Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics

    DOE Patents [OSTI]

    Becher, Paul F. (Oak Ridge, TN); Lin, Hua-Tay (Oak Ridge, TN)

    2011-06-28T23:59:59.000Z

    A high-strength, fracture-resistant silicon nitride ceramic material that includes about 5 to about 75 wt-% of elongated reinforcing grains of beta-silicon nitride, about 20 to about 95 wt-% of fine grains of beta-silicon nitride, wherein the fine grains have a major axis of less than about 1 micron; and about 1 to about 15 wt-% of an amorphous intergranular phase comprising Si, N, O, a rare earth element and a secondary densification element. The elongated reinforcing grains have an aspect ratio of 2:1 or greater and a major axis measuring about 1 micron or greater. The elongated reinforcing grains are essentially isotropically oriented within the ceramic microstructure. The silicon nitride ceramic exhibits a room temperature flexure strength of 1,000 MPa or greater and a fracture toughness of 9 MPa-m.sup.(1/2) or greater. The silicon nitride ceramic exhibits a peak strength of 800 MPa or greater at 1200 degrees C. Also included are methods of making silicon nitride ceramic materials which exhibit the described high flexure strength and fracture-resistant values.

  3. Silver delafossite nitride, AgTaN{sub 2}?

    SciTech Connect (OSTI)

    Miura, Akira [Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen (Germany); Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States); Lowe, Michael; Leonard, Brian M.; Subban, Chinmayee V. [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States); Masubuchi, Yuji; Kikkawa, Shinichi [Graduate School of Engineering, Hokkaido University, N13W8, Kita-ku Sapporo 060-8628 (Japan); Dronskowski, Richard [Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen (Germany); Hennig, Richard G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Abruna, Hector D. [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States); DiSalvo, Francis J., E-mail: fjd3@cornell.ed [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States)

    2011-01-15T23:59:59.000Z

    A new silver nitride, AgTaN{sub 2}, was synthesized from NaTaN{sub 2} by a cation-exchange reaction, using a AgNO{sub 3}-NH{sub 4}NO{sub 3} flux at 175 {sup o}C. Its crystal structure type is delafossite (R3-bar m) with hexagonal lattice parameters of a=3.141(3) A, c=18.81(2) A, in which silver is linearly coordinated to nitrogen. Energy dispersive X-ray analysis and combustion nitrogen/oxygen analysis gave a composition with atomic ratios of Ag:Ta:N:O as 1.0:1.2(1):2.1(1):0.77(4), which is somewhat Ta rich and indicates some oxide formation. The X-ray photoelectron spectroscopy analysis showed a Ta- and O-rich surface and transmission electron microscope observation exhibited aggregates of ca. 4-5 nm-sized particles on the surface, which are probably related to the composition deviation from a AgTaN{sub 2}. The lattice parameters of stoichiometric AgTaN{sub 2} calculated by density functional theory agree with the experimental ones, but the possibility of some oxygen incorporation and/or silver deficiency is not precluded. -- Graphical abstract: A delafossite silver nitride, AgTaN{sub 2}, was synthesized from NaTaN{sub 2} by a cation-exchange reaction using a AgNO{sub 3}-NH{sub 4}NO{sub 3} flux. It contains N-Ag-N linear bonding. Display Omitted

  4. Real-time x-ray studies of gallium nitride nanodot formation by droplet heteroepitaxy

    SciTech Connect (OSTI)

    Wang Yiyi; Oezcan, Ahmet S.; Sanborn, Christopher; Ludwig, Karl F.; Bhattacharyya, Anirban; Chandrasekaran, Ramya; Moustakas, Theodore D.; Zhou Lin; Smith, David J. [Physics Department, Boston University, Boston, Massachusetts 02215 (United States); Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Department of Physics, Arizona State University, Tempe, Arizona 85287, USA and School of Materials, Arizona State University, Tempe, Arizona 85287 (United States)

    2007-10-01T23:59:59.000Z

    Self-organized gallium nitride nanodots have been fabricated using droplet heteroepitaxy on c-plane sapphire by plasma-assisted molecular beam epitaxy at different substrate temperatures and Ga fluxes. Nanoscale Ga droplets were initially formed on the sapphire substrate at high temperatures by Ga deposition from an effusion cell in an ultrahigh vacuum growth chamber. Subsequently, the droplets were converted into GaN nanodots using a nitrogen plasma source. The process was monitored and controlled using real-time grazing-incidence small-angle x-ray scattering. The samples were examined postgrowth by in situ grazing incidence x-ray diffraction and reflection high-energy electron diffraction, which confirmed the epitaxial relationship between the GaN nanodots and the sapphire surface. X-ray diffraction indicated that the wurtzite phase was dominant at higher substrate temperature (710 deg. C), but a mixture of wurtzite and zinc blende phases was present at a substrate temperature of 620 deg. C. Ex situ atomic force microscopy and transmission electron microscopy analyses showed that the dot size distribution was bimodal. A thin GaN continuous layer of {approx} three monolayers thick was observed by transmission electron microscopy on the sample grown at a substrate temperature of 620 deg. C, but no such layer was observed for the substrate temperature of 710 deg. C. This suggests that there is little mobility of Ga atoms in contact with the sapphire substrate at the lower temperature so that they cannot easily diffuse to nearby droplets and instead form a thin layer covering the surface.

  5. Real-Time X-ray Studies of Gallium Nitride Nanodot Formation by Droplet Heteroepitaxy

    SciTech Connect (OSTI)

    Wang,Y.; Ozcan, A.; Sanborn, C.; Ludwig, K.; Bhattacharyya, A.; Chandrasekaran, R.; Moustakas, T.; Zhou, L.; Smith, D.

    2007-01-01T23:59:59.000Z

    Self-organized gallium nitride nanodots have been fabricated using droplet heteroepitaxy on c-plane sapphire by plasma-assisted molecular beam epitaxy at different substrate temperatures and Ga fluxes. Nanoscale Ga droplets were initially formed on the sapphire substrate at high temperatures by Ga deposition from an effusion cell in an ultrahigh vacuum growth chamber. Subsequently, the droplets were converted into GaN nanodots using a nitrogen plasma source. The process was monitored and controlled using real-time grazing-incidence small-angle x-ray scattering. The samples were examined postgrowth by in situ grazing incidence x-ray diffraction and reflection high-energy electron diffraction, which confirmed the epitaxial relationship between the GaN nanodots and the sapphire surface. X-ray diffraction indicated that the wurtzite phase was dominant at higher substrate temperature (710? C), but a mixture of wurtzite and zinc blende phases was present at a substrate temperature of 620? C. Ex situ atomic force microscopy and transmission electron microscopy analyses showed that the dot size distribution was bimodal. A thin GaN continuous layer of ? three monolayers thick was observed by transmission electron microscopy on the sample grown at a substrate temperature of 620? C, but no such layer was observed for the substrate temperature of 710? C. This suggests that there is little mobility of Ga atoms in contact with the sapphire substrate at the lower temperature so that they cannot easily diffuse to nearby droplets and instead form a thin layer covering the surface.

  6. Applicability of carbon and boron nitride nanotubes as biosensors: Effect of biomolecular adsorption on the transport properties of carbon and boron

    E-Print Network [OSTI]

    Pandey, Ravi

    Applicability of carbon and boron nitride nanotubes as biosensors: Effect of biomolecular;Applicability of carbon and boron nitride nanotubes as biosensors: Effect of biomolecular adsorption University, Houghton, Michigan 49931, USA 2 US Army Research Laboratory, Weapons and Materials Research

  7. Advanced Epi Tools for Gallium Nitride Light Emitting Diode Devices

    SciTech Connect (OSTI)

    Patibandla, Nag; Agrawal, Vivek

    2012-12-01T23:59:59.000Z

    Over the course of this program, Applied Materials, Inc., with generous support from the United States Department of Energy, developed a world-class three chamber III-Nitride epi cluster tool for low-cost, high volume GaN growth for the solid state lighting industry. One of the major achievements of the program was to design, build, and demonstrate the world’s largest wafer capacity HVPE chamber suitable for repeatable high volume III-Nitride template and device manufacturing. Applied Materials’ experience in developing deposition chambers for the silicon chip industry over many decades resulted in many orders of magnitude reductions in the price of transistors. That experience and understanding was used in developing this GaN epi deposition tool. The multi-chamber approach, which continues to be unique in the ability of the each chamber to deposit a section of the full device structure, unlike other cluster tools, allows for extreme flexibility in the manufacturing process. This robust architecture is suitable for not just the LED industry, but GaN power devices as well, both horizontal and vertical designs. The new HVPE technology developed allows GaN to be grown at a rate unheard of with MOCVD, up to 20x the typical MOCVD rates of 3{micro}m per hour, with bulk crystal quality better than the highest-quality commercial GaN films grown by MOCVD at a much cheaper overall cost. This is a unique development as the HVPE process has been known for decades, but never successfully commercially developed for high volume manufacturing. This research shows the potential of the first commercial-grade HVPE chamber, an elusive goal for III-V researchers and those wanting to capitalize on the promise of HVPE. Additionally, in the course of this program, Applied Materials built two MOCVD chambers, in addition to the HVPE chamber, and a robot that moves wafers between them. The MOCVD chambers demonstrated industry-leading wavelength yield for GaN based LED wafers and industry-leading uptime enabled in part by a novel in-situ cleaning process developed in this program.

  8. Polymerized carbon nitride nanobells G. Y. Zhang, X. C. Ma, D. Y. Zhong, and E. G. Wanga)

    E-Print Network [OSTI]

    Zhang, Guangyu

    Polymerized carbon nitride nanobells G. Y. Zhang, X. C. Ma, D. Y. Zhong, and E. G. Wanga) State Key Academy of Sciences, Beijing 100080, People's Republic of China Received 12 November 2001; accepted for publication 8 March 2002 Well-aligned carbon nitride nanotubes are fabricated by microwave plasma assisted

  9. Diffusion of nitrogen implanted in titanium nitride (TiN1-x) F. Abautret and P. Eveno

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1113 Diffusion of nitrogen implanted in titanium nitride (TiN1- x) F. Abautret and P. Eveno The diffusion of nitrogen 15, implanted in non-stoichiometric titanium nitride single-crystals (03B4 - TiN1-x on i usion m m ri es compared with the oxides. No data are available about nitrogen (or titanium

  10. Single-Photon Detection, Kinetic Inductance, and Non-Equilibrium Dynamics in Niobium and Niobium Nitride Superconducting Nanowires

    E-Print Network [OSTI]

    Devoret, Michel H.

    Abstract Single-Photon Detection, Kinetic Inductance, and Non-Equilibrium Dynamics in Niobium and Niobium Nitride Superconducting Nanowires Anthony Joseph Annunziata 2010 This thesis is a study of superconducting niobium and niobium nitride nanowires used as single optical and near-infrared photon detectors

  11. hal-00132485,version1-21Feb2007 Liquid nitrogen to room temperature thermometry using niobium nitride thin films

    E-Print Network [OSTI]

    Boyer, Edmond

    hal-00132485,version1-21Feb2007 Liquid nitrogen to room temperature thermometry using niobium´eel, CNRS-UJF, 25 avenue des Martyrs, 38042 Grenoble, France (Dated: February 21, 2007) Niobium nitride thin, the interesting properties of niobium nitride (NbN) as well as amorphous Nb-Si have been ex- tensively used

  12. From localization to superconductivity in granular niobium nitride thin R. Cabanel (**), J. Chaussy, J. Mazuer and J. C. Villegier (1)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    795 From localization to superconductivity in granular niobium nitride thin films (*) R. Cabanel 300 K les variations de la résistivité de films de nitrure de niobium préparés par pulvérisation.60 - 74.70D - 81.15C Introduction. Niobium nitride studies extensively grew during the past twenty years

  13. Graphitic carbon nitride materials: variation of structure and morphology and their use as metal-free catalysts

    E-Print Network [OSTI]

    properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene, trimerization reactions, and also the activation of carbon dioxide. Model calculationsGraphitic carbon nitride materials: variation of structure and morphology and their use as metal

  14. HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING

    SciTech Connect (OSTI)

    Paul T. Fini; Shuji Nakamura

    2003-10-30T23:59:59.000Z

    In this second annual report we summarize the progress in the second-year period of Department of Energy contract DE-FC26-01NT41203, entitled ''High- Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has recently made significant progress in the development of light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV), resonant-cavity LEDs (RCLEDs), as well as lateral epitaxial overgrowth (LEO) techniques to obtain large-area non-polar GaN films with low average dislocation density. The Rensselaer team has benchmarked the performance of commercially available LED systems and has also conducted efforts to develop an optimized RCLED packaging scheme, including development of advanced epoxy encapsulant chemistries.

  15. Mechanical deformations of boron nitride nanotubes in crossed junctions

    SciTech Connect (OSTI)

    Zhao, Yadong; Chen, Xiaoming; Ke, Changhong, E-mail: cke@binghamton.edu [Department of Mechanical Engineering, State University of New York at Binghamton, Binghamton, New York 13902 (United States); Park, Cheol [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Fay, Catharine C. [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Stupkiewicz, Stanislaw [Institute of Fundamental Technological Research, Warsaw (Poland)

    2014-04-28T23:59:59.000Z

    We present a study of the mechanical deformations of boron nitride nanotubes (BNNTs) in crossed junctions. The structure and deformation of the crossed tubes in the junction are characterized by using atomic force microscopy. Our results show that the total tube heights are reduced by 20%–33% at the crossed junctions formed by double-walled BNNTs with outer diameters in the range of 2.21–4.67?nm. The measured tube height reduction is found to be in a nearly linear relationship with the summation of the outer diameters of the two tubes forming the junction. The contact force between the two tubes in the junction is estimated based on contact mechanics theories and found to be within the range of 4.2–7.6 nN. The Young's modulus of BNNTs and their binding strengths with the substrate are quantified, based on the deformation profile of the upper tube in the junction, and are found to be 1.07?±?0.11 TPa and 0.18–0.29 nJ/m, respectively. Finally, we perform finite element simulations on the mechanical deformations of the crossed BNNT junctions. The numerical simulation results are consistent with both the experimental measurements and the analytical analysis. The results reported in this paper contribute to a better understanding of the structural and mechanical properties of BNNTs and to the pursuit of their applications.

  16. HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING

    SciTech Connect (OSTI)

    Dr. Paul T. Fini; Prof. Shuji Nakamura

    2002-04-30T23:59:59.000Z

    In this semiannual report we summarize the progress obtained in the first six months with the support of DoE contract No.DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has made significant progress in the development of GaN vertical cavity surface-emitting lasers (VCSELs) as well as light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV). The Rensselaer team has developed target specifications for some of the key parameters for the proposed solid-state lighting system, including a luminous flux requirement matrix for various lighting applications, optimal spectral power distributions, and the performance characteristics of currently available commercial LEDs for eventual comparisons to the devices developed in the scope of this project.

  17. HIGH-EFFICIENCY NITRIDE-BASED SOLID-STATE LIGHTING

    SciTech Connect (OSTI)

    Dr. Paul T. Fini; Prof. Shuji Nakamura

    2002-09-01T23:59:59.000Z

    In this annual report we summarize the progress obtained in the first year with the support of DoE contract No.DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. The two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and Rensselaer Polytechnic Institute (led by Dr. N. Narendran), are pursuing the goals of this contract from thin film growth, characterization, and packaging standpoints. The UCSB team has made significant progress in the development of GaN vertical cavity surface-emitting lasers (VCSELs) as well as light-emitting diodes (LEDs) with AlGaN active regions emitting in the ultraviolet (UV). The Rensselaer team has developed target specifications for some of the key parameters for the proposed solid-state lighting system, including a luminous flux requirement matrix for various lighting applications, optimal spectral power distributions, and the performance characteristics of currently available commercial LEDs for eventual comparisons to the devices developed in the scope of this project.

  18. Synthesis of fine-grained .alpha.-silicon nitride by a combustion process

    DOE Patents [OSTI]

    Holt, J. Birch (San Jose, CA); Kingman, Donald D. (Danville, CA); Bianchini, Gregory M. (Livermore, CA)

    1990-01-01T23:59:59.000Z

    A combustion synthesis process for the preparation of .alpha.-silicon nitride and composites thereof is disclosed. Preparation of the .alpha.-silicon nitride comprises the steps of dry mixing silicon powder with an alkali metal azide, such as sodium azide, cold-pressing the mixture into any desired shape, or loading the mixture into a fused, quartz crucible, loading the crucible into a combustion chamber, pressurizing the chamber with nitrogen and igniting the mixture using an igniter pellet. The method for the preparation of the composites comprises dry mixing silicon powder (Si) or SiO.sub.2, with a metal or metal oxide, adding a small amount of an alkali metal azide such as sodium azide, introducing the mixture into a suitable combustion chamber, pressurizing the combustion chamber with nitrogen, igniting the mixture within the combustion chamber, and isolating the .alpha.-silicon nitride formed as a reaction product.

  19. The different adsorption mechanism of methane molecule onto a boron nitride and a graphene flakes

    SciTech Connect (OSTI)

    Seyed-Talebi, Seyedeh Mozhgan [Shahid Chamran University, Golestan boulevard, Ahvaz, Khouzestan (Iran, Islamic Republic of); Neek-Amal, M., E-mail: neekamal@srttu.edu [Shahid Rajaee Teacher Training University, Lavizan, Tehran (Iran, Islamic Republic of)

    2014-10-21T23:59:59.000Z

    Graphene and single layer hexagonal boron-nitride are two newly discovered 2D materials with wonderful physical properties. Using density functional theory, we study the adsorption mechanism of a methane molecule over a hexagonal flake of single layer hexagonal boron-nitride (h-BN) and compare the results with those of graphene. We found that independent of the used functional in our ab-initio calculations, the adsorption energy in the h-BN flake is larger than that for graphene. Despite of the adsorption energy profile of methane over a graphene flake, we show that there is a long range behavior beyond minimum energy in the adsorption energy of methane over h-BN flake. This result reveals the higher sensitivity of h-BN sheet to the adsorption of a typical closed shell molecule with respect to graphene. The latter gives insight in the recent experiments of graphene over hexagonal boron nitride.

  20. The internal-nitriding behavior of Co-Fe-Al alloys

    SciTech Connect (OSTI)

    Chen, I.C. [Raytheon Systems Co., El Segundo, CA (United States). Sensors and Electronics Systems] [Raytheon Systems Co., El Segundo, CA (United States). Sensors and Electronics Systems; Douglass, D.L. [Univ. of Arizona, Tucson, AZ (United States). Arizona Materials Labs.] [Univ. of Arizona, Tucson, AZ (United States). Arizona Materials Labs.

    1999-10-01T23:59:59.000Z

    Co-10Fe, Co-20Fe, and Co-40Fe alloys containing 3 at.% Al were internally nitrided in NH{sub 3}/H{sub 2} mixtures over the range 700--1000 C. The kinetics of thickening of the internal-reaction zone followed the parabolic rate law, suggesting that solid-state diffusion was rate controlling. Nitrogen permeabilities were obtained for each alloy. AlN was the only nitride to form for all materials and at all temperatures. At high temperature, the nitride precipitates formed hexagonal plates near the surface, the precipitates becoming more blocky near the reaction front. Precipitate size increased with increasing depth in the alloy and increasing temperature, because of competition between nucleation and growth processes. Increasing iron content increased the reaction kinetics due to increased nitrogen solubility with increasing iron content.

  1. Microstructural characterization of silicon nitride ceramics processed by pressureless sintering, overpressure sintering, and sinter/HIP

    SciTech Connect (OSTI)

    Selkregg, K.R. (Oak Ridge National Lab., TN (USA)); More, K.L.; Seshadri, S.G.; McMurtry, C.H. (Carborundum Co., Niagara Falls, NY (USA))

    1990-01-01T23:59:59.000Z

    Silicon nitride ceramics of the same nominal sialon composition have been sintered under different conditions including atmospheric sintering, overpressure sintering, reaction bonded (nitrided pressureless sinter) and sinter/HIP cycles. The sintered ceramics, which exhibited dramatic differences in fracture toughness, have been characterized by x-ray diffraction, scanning electron microscopy, analytical transmission electron microscopy, and image analysis techniques. Fracture toughness data have been correlated to the microstructural and chemical analysis of the grain boundary phases. The microstructure was the strongest influencing factor on the observed fracture toughness difference. 5 refs., 5 tabs.

  2. Assessing cytotoxicity of boron nitride nanotubes: Interference with the MTT assay

    SciTech Connect (OSTI)

    Ciofani, Gianni, E-mail: g.ciofani@sssup.it [Italian Institute of Technology, Smart Materials Lab, Center of MicroBioRobotics at Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy)] [Italian Institute of Technology, Smart Materials Lab, Center of MicroBioRobotics at Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy); Danti, Serena; D'Alessandro, Delfo [Otology-Cochlear Implants, Cisanello Hospital, Via Paradisa 2, 56124 Pisa (Italy)] [Otology-Cochlear Implants, Cisanello Hospital, Via Paradisa 2, 56124 Pisa (Italy); Moscato, Stefania [Department of Human Morphology and Applied Biology, University of Pisa, Via Roma 55, 56126 Pisa (Italy)] [Department of Human Morphology and Applied Biology, University of Pisa, Via Roma 55, 56126 Pisa (Italy); Menciassi, Arianna [Italian Institute of Technology, Smart Materials Lab, Center of MicroBioRobotics at Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy) [Italian Institute of Technology, Smart Materials Lab, Center of MicroBioRobotics at Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy); CRIM Lab, Scuola Superiore Sant'Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy)

    2010-04-02T23:59:59.000Z

    Thanks to a non-covalent wrapping with glycol-chitosan, highly biocompatible and highly concentrated dispersions of boron nitride nanotubes were obtained and tested on human neuroblastoma cells. A systematic investigation of the cytotoxicity of these nanovectors with several complementary qualitative and quantitative assays allowed a strong interference with the MTT metabolic assay to be highlighted, similar to a phenomenon already observed for carbon nanotubes, that would wrongly suggest toxicity of boron nitride nanotubes. These results confirm the high complexity of these new nanomaterials, and the needing of extensive investigations on their exciting potential applications in the biomedical field.

  3. Efficient boron nitride nanotube formation via combined laser-gas flow levitation

    DOE Patents [OSTI]

    Whitney, R. Roy; Jordan, Kevin; Smith, Michael

    2014-03-18T23:59:59.000Z

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.sub.z. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.sub.z.

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

    SciTech Connect (OSTI)

    Alam, M. T.; Haque, M. A., E-mail: mah37@psu.edu [Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Bresnehan, M. S.; Robinson, J. A. [Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA and The Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA and The Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-01-06T23:59:59.000Z

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

  5. Improved porous mixture of molybdenum nitride and tantalum oxide as a charge storage material

    SciTech Connect (OSTI)

    Deng, C.Z.; Pynenburg, R.A.J.; Tsai, K.C. [Pinnacle Research Inst., Inc., Los Gatos, CA (United States)

    1998-04-01T23:59:59.000Z

    High surface area {gamma}-molybdenum nitride has shown promise as a charge storage material. The addition of amorphous tantalum oxide to the molybdenum nitride system not only improves the film cohesion tremendously, but also widens the voltage stability window from 0.8 to 1.1 V. This occurs without adversely effecting the capacitance. Ultracapacitors, also called supercapacitors or electrochemical capacitors, are high power storage devices which have found application in products as diverse as cardiac pacemakers, cellular phones, electric vehicles, and air bags.

  6. High-Efficiency Nitride-Based Solid-State Lighting

    SciTech Connect (OSTI)

    Paul T. Fini; Shuji Nakamura

    2005-07-30T23:59:59.000Z

    In this final technical progress report we summarize research accomplished during Department of Energy contract DE-FC26-01NT41203, entitled ''High-Efficiency Nitride-Based Solid-State Lighting''. Two teams, from the University of California at Santa Barbara (Principle Investigator: Dr. Shuji Nakamura) and the Lighting Research Center at Rensselaer Polytechnic Institute (led by Dr. N. Narendran), pursued the goals of this contract from thin film growth, characterization, and packaging/luminaire design standpoints. The UCSB team initially pursued the development of blue gallium nitride (GaN)-based vertical-cavity surface-emitting lasers, as well as ultraviolet GaN-based light emitting diodes (LEDs). In Year 2, the emphasis shifted to resonant-cavity light emitting diodes, also known as micro-cavity LEDs when extremely thin device cavities are fabricated. These devices have very directional emission and higher light extraction efficiency than conventional LEDs. Via the optimization of thin-film growth and refinement of device processing, we decreased the total cavity thickness to less than 1 {micro}m, such that micro-cavity effects were clearly observed and a light extraction efficiency of over 10% was reached. We also began the development of photonic crystals for increased light extraction, in particular for so-called ''guided modes'' which would otherwise propagate laterally in the device and be re-absorbed. Finally, we pursued the growth of smooth, high-quality nonpolar a-plane and m-plane GaN films, as well as blue light emitting diodes on these novel films. Initial nonpolar LEDs showed the expected behavior of negligible peak wavelength shift with increasing drive current. M-plane LEDs in particular show promise, as unpackaged devices had unsaturated optical output power of {approx} 3 mW at 200 mA drive current. The LRC's tasks were aimed at developing the subcomponents necessary for packaging UCSB's light emitting diodes, and packaging them to produce a white light fixture. During the third and final year of the project, the LRC team investigated alternate packaging methods for the white LED device to achieve at least 25 percent more luminous efficacy than traditional white LEDs; conducted optical ray-tracing analyses and human factors studies to determine the best form factor for the white light source under development, in terms of high luminous efficacy and greater acceptance by subjects; and developed a new die encapsulant using silicone-epoxy resins that showed less yellowing and slower degradation. At the conclusion of this project, the LRC demonstrated a new packaging method, called scattered photon extraction (SPE), that produced an average luminous flux and corresponding average efficacy of 90.7 lm and 36.3 lm/W, respectively, compared with 56.5 lm and 22.6 lm/W for a similar commercial white LED package. At low currents, the SPE package emitted white light with an efficacy of over 80 lm/W and had chromaticity values very close to the blackbody locus. The SPE package showed an overall improvement of 61% for this particular comparison, exceeding the LRC's third-year goal of 25% improvement.

  7. Anisotropic Hexagonal Boron Nitride Nanomaterials - Synthesis and Applications

    SciTech Connect (OSTI)

    Han,W.Q.

    2008-08-01T23:59:59.000Z

    Boron nitride (BN) is a synthetic binary compound located between III and V group elements in the Periodic Table. However, its properties, in terms of polymorphism and mechanical characteristics, are rather close to those of carbon compared with other III-V compounds, such as gallium nitride. BN crystallizes into a layered or a tetrahedrally linked structure, like those of graphite and diamond, respectively, depending on the conditions of its preparation, especially the pressure applied. Such correspondence between BN and carbon readily can be understood from their isoelectronic structures [1, 2]. On the other hand, in contrast to graphite, layered BN is transparent and is an insulator. This material has attracted great interest because, similar to carbon, it exists in various polymorphic forms exhibiting very different properties; however, these forms do not correspond strictly to those of carbon. Crystallographically, BN is classified into four polymorphic forms: Hexagonal BN (h-BN) (Figure 1(b)); rhombohedral BN (r-BN); cubic BN (c-BN); and wurtzite BN (w-BN). BN does not occur in nature. In 1842, Balmain [3] obtained BN as a reaction product between molten boric oxide and potassium cyanide under atmospheric pressure. Thereafter, many methods for its synthesis were reported. h-BN and r-BN are formed under ambient pressure. c-BN is synthesized from h-BN under high pressure at high temperature while w-BN is prepared from h-BN under high pressure at room temperature [1]. Each BN layer consists of stacks of hexagonal plate-like units of boron and nitrogen atoms linked by SP{sup 2} hybridized orbits and held together mainly by Van der Waals force (Fig 1(b)). The hexagonal polymorph has two-layered repeating units: AA'AA'... that differ from those in graphite: ABAB... (Figure 1(a)). Within the layers of h-BN there is coincidence between the same phases of the hexagons, although the boron atoms and nitrogen atoms are alternatively located along the c-axis. The rhombohedral system consists of three-layered units: ABCABC..., whose honeycomb layers are arranged in a shifted phase, like as those of graphite. Reflecting its weak interlayer bond, the h-BN can be cleaved easily along its layers, and hence, is widely used as a lubricant material. The material is stable up to a high temperature of 2300 C before decomposition sets in [2] does not fuse a nitrogen atmosphere of 1 atm, and thus, is applicable as a refractory material. Besides having such properties, similar to those of graphite, the material is transparent, and acts as a good electric insulator, especially at high temperatures (10{sup 6} {Omega}m at 1000 C) [1]. c-BN and w-BN are tetrahedrally linked BN. The former has a cubic sphalerite-type structure, and the latter has a hexagonal wurtzite-type structure. c-BN is the second hardest known material (the hardest is diamond), the so-called white diamond. It is used mainly for grinding and cutting industrial ferrous materials because it does not react with molten iron, nickel, and related alloys at high temperatures whereas diamond does [1]. It displays the second highest thermal conductivity (6-9 W/cm.deg) after diamond. This chapter focuses principally upon information about h-BN nanomaterials, mainly BN nanotubes (BNNTs), porous BN, mono- and few-layer-BN sheets. There are good reviews book chapters about c-BN in [1, 4-6].

  8. Desorption and sublimation kinetics for fluorinated aluminum nitride surfaces

    SciTech Connect (OSTI)

    King, Sean W., E-mail: sean.king@intel.com; Davis, Robert F. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Nemanich, Robert J. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-09-01T23:59:59.000Z

    The adsorption and desorption of halogen and other gaseous species from surfaces is a key fundamental process for both wet chemical and dry plasma etch and clean processes utilized in nanoelectronic fabrication processes. Therefore, to increase the fundamental understanding of these processes with regard to aluminum nitride (AlN) surfaces, temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) have been utilized to investigate the desorption kinetics of water (H{sub 2}O), fluorine (F{sub 2}), hydrogen (H{sub 2}), hydrogen fluoride (HF), and other related species from aluminum nitride thin film surfaces treated with an aqueous solution of buffered hydrogen fluoride (BHF) diluted in methanol (CH{sub 3}OH). Pre-TPD XPS measurements of the CH{sub 3}OH:BHF treated AlN surfaces showed the presence of a variety of Al-F, N-F, Al-O, Al-OH, C-H, and C-O surfaces species in addition to Al-N bonding from the AlN thin film. The primary species observed desorbing from these same surfaces during TPD measurements included H{sub 2}, H{sub 2}O, HF, F{sub 2}, and CH{sub 3}OH with some evidence for nitrogen (N{sub 2}) and ammonia (NH{sub 3}) desorption as well. For H{sub 2}O, two desorption peaks with second order kinetics were observed at 195 and 460?°C with activation energies (E{sub d}) of 51?±?3 and 87?±?5?kJ/mol, respectively. Desorption of HF similarly exhibited second order kinetics with a peak temperature of 475?°C and E{sub d} of 110?±?5?kJ/mol. The TPD spectra for F{sub 2} exhibited two peaks at 485 and 585?°C with second order kinetics and E{sub d} of 62?±?3 and 270?±?10?kJ/mol, respectively. These values are in excellent agreement with previous E{sub d} measurements for desorption of H{sub 2}O from SiO{sub 2} and AlF{sub x} from AlN surfaces, respectively. The F{sub 2} desorption is therefore attributed to fragmentation of AlF{sub x} species in the mass spectrometer ionizer. H{sub 2} desorption exhibited an additional high temperature peak at 910?°C with E{sub d}?=?370?±?10?kJ/mol that is consistent with both the dehydrogenation of surface AlOH species and H{sub 2} assisted sublimation of AlN. Similarly, N{sub 2} exhibited a similar higher temperature desorption peak with E{sub d}?=?535?±?40?kJ/mol that is consistent with the activation energy for direct sublimation of AlN.

  9. Veeco

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to design indium gallium nitride (InGaN) MOCVD growth systems. The actual experimental GaN non-uniformity is about four times greater than predicted because the model does not...

  10. The influence of random indium alloy fluctuations in indium gallium nitride quantum wells on the device behavior

    SciTech Connect (OSTI)

    Yang, Tsung-Jui; Wu, Yuh-Renn, E-mail: yrwu@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Shivaraman, Ravi; Speck, James S. [Department of Materials, University of California, Santa Barbara, California 93106 (United States)

    2014-09-21T23:59:59.000Z

    In this paper, we describe the influence of the intrinsic indium fluctuation in the InGaN quantum wells on the carrier transport, efficiency droop, and emission spectrum in GaN-based light emitting diodes (LEDs). Both real and randomly generated indium fluctuations were used in 3D simulations and compared to quantum wells with a uniform indium distribution. We found that without further hypothesis the simulations of electrical and optical properties in LEDs such as carrier transport, radiative and Auger recombination, and efficiency droop are greatly improved by considering natural nanoscale indium fluctuations.

  11. Experimental Analysis of the Elastic Plastic Transition During Nanoindentation of Single Crystal a-Silicon Nitride

    SciTech Connect (OSTI)

    Jang, Jae-il [Hanyang University, Korea; Bei, Hongbin [ORNL; Becher, Paul F [ORNL; Pharr, George M [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL)

    2012-01-01T23:59:59.000Z

    The elastic-to-plastic transition in single crystal a-silicon nitride was experimentally characterized through a series of nanoindentation experiments using a spherical indenter. The experimental results provide a quantitative description of the critical shear strengths for the transition, as well as estimates of the shear modulus and nanohardness of the material.

  12. Assessment of uranium-free nitride fuels for spent fuel transmutation in fast reactor systems

    E-Print Network [OSTI]

    Szakaly, Frank Joseph

    2004-09-30T23:59:59.000Z

    The purpose of this work is to investigate the implementation of nitride fuels containing little or no uranium in a fast-spectrum nuclear reactor to reduce the amount of plutonium and minor actinides in spent nuclear fuel destined for the Yucca...

  13. Effect of swift heavy ion irradiations in polycrystalline aluminum nitride J.C. Nappa,*

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    conductivity, aluminum nitride may be a serious candidate as fuel coating for the Gas Fast Reactor. However.41.Bm, 78.60.Kn, 78.20.Ci 1. Introduction Gas Fast Reactor (GFR) is one of the six new systems is also studied in the framework of fusion reactors, in which this material, thanks to its high electrical

  14. Spontaneous Spatial Alignment of Polymer Cylindrical Nanodomains on Silicon Nitride Gratings

    E-Print Network [OSTI]

    Sibener, Steven

    a simple method to align lying-down cylindrical domains of PS-b-PMMA in the trough regions of 555 nm deepSpontaneous Spatial Alignment of Polymer Cylindrical Nanodomains on Silicon Nitride Gratings Deepak to the orientation of the grating lines and essentially spans the width of the grating trough. The proposed mechanism

  15. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOE Patents [OSTI]

    Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

    1999-01-01T23:59:59.000Z

    A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  16. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOE Patents [OSTI]

    Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

    2002-01-01T23:59:59.000Z

    A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  17. Practical Issues for Atom Probe Tomography Analysis of III-Nitride Semiconductor Materials

    E-Print Network [OSTI]

    Tanga, Fengzai; Moodya, Michael P.; Martina, Tomas L.; Bagota, Paul A. J.; Kappersa, Menno J.; Oliver, Rachel A.

    2015-04-30T23:59:59.000Z

    study of Cu grains 385 (Kempshall, et al., 2001). In terms of binary III-nitrides, the metal–N bond length in the 386 wurtzite structure increases from AlN, to GaN and to InN (Ambacher, 1998), being 387 associated with corresponding bond energy of 2...

  18. Theoretical study of nonpolar surfaces of aluminum nitride: Zinc blende ,,110... and wurtzite ,,1010...

    E-Print Network [OSTI]

    Pandey, Ravi

    Theoretical study of nonpolar surfaces of aluminum nitride: Zinc blende ,,110... and wurtzite ,,101 structure and electronic properties of the nonpolar surfaces, namely zinc blende 110 and wurtzite (10 1 and small ther- mal expansion coefficient. At ambient conditions, AlN crys- tallizes in the wurtzite phase

  19. Line-source E beam crystallization of Si on silicon nitride layers

    SciTech Connect (OSTI)

    Knapp, J.A.; Picraux, S.T.; Lee, K.; Gibbons, J.F.; Sedgwick, T.O.; Depp, S.W.

    1981-01-01T23:59:59.000Z

    The use of a swept line-source electron beam is reported for liquid phase recrystallization of Si films on Si/sub 3/N/sub 4/ layers over Si substrates. For the case of 5000A of Si on 1000A of Si/sub 3/N/sub 4/ layers over Si the growth of Si crystalline regions as large as 0.5 x 5 mm of predominately (100) orientation normal to the film and (010) in the sweep direction has been demonstrated. The nucleation of grain growth for this case occurred at small defects in the nitride layer at the edge of the treated area, growing out as far as 500 ..mu..m over intact nitride. Thicker nitrides (2500A) remained intact at power densities useful for treating the Si film. For this thicker nitride non-seeded growth is demonstrated for single and repetitively melted Si. In all cases the surface morphology of the regrown regions is suggestive of rapid growth along <100> directions.

  20. CHARGE STABILITY IN LPCVD SILICON NITRIDE FOR SURFACE PASSIVATION OF SILICON SOLAR CELLS

    E-Print Network [OSTI]

    CHARGE STABILITY IN LPCVD SILICON NITRIDE FOR SURFACE PASSIVATION OF SILICON SOLAR CELLS Yongling Ren, Natalita M Nursam, Da Wang and Klaus J Weber Centre for Sustainable Energy Systems, College of Engineering and Computer Science, The Australian National University, Canberra, ACT 0200, Australia ABSTRACT

  1. Reversible Intercalation of Hexagonal Boron Nitride with Brnsted Nina I. Kovtyukhova,*,

    E-Print Network [OSTI]

    materials.1-3 Intercalation reactions are often used as the first step in exfoliation of lamellar crystals dichalogenides,10,12 and hexagonal boron nitride (h-BN)13-15 can be mechanically exfoliated to form crystalline, several solution-based chem- ical approaches have been studied.10,16-22 Among these, only exfoliation

  2. ORDER AND DISORDER IN CARBIDES AND NITRIDES Ch. H. DE NOVION and V. MAURICE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    transition metals, rare earths and actinides react with carbon and nitrogen to form metallic carbides or nitrogen 2p atomic electron states : they may be described by a stacking of units consisting of a central and nitrides is their large composition range, for example Tico.,, to Tic,.,, for titanium mono- carbide

  3. Monolayer Passivation of Ge(100) Surface via Nitridation and Oxidation Joon Sung Leea,b

    E-Print Network [OSTI]

    Kummel, Andrew C.

    Monolayer Passivation of Ge(100) Surface via Nitridation and Oxidation Joon Sung Leea,b , Sarah R passivation of Ge(100) surface via formation of Ge-N and Ge-O surface species was studied using scanning cyclotron resonance (ECR) plasma source formed an ordered Ge-N structure on a Ge(100) surface at 500o C. DFT

  4. Epitaxial ternary nitride thin films prepared by a chemical solution method

    SciTech Connect (OSTI)

    Luo, Hongmei [Los Alamos National Laboratory; Feldmann, David M [Los Alamos National Laboratory; Wang, Haiyan [TEXAS A& M; Bi, Zhenxing [TEXAS A& M

    2008-01-01T23:59:59.000Z

    It is indispensable to use thin films for many technological applications. This is the first report of epitaxial growth of ternary nitride AMN2 films. Epitaxial tetragonal SrTiN2 films have been successfully prepared by a chemical solution approach, polymer-assisted deposition. The structural, electrical, and optical properties of the films are also investigated.

  5. Group III-nitride thin films grown using MBE and bismuth

    DOE Patents [OSTI]

    Kisielowski, Christian K. (Peidmont, CA); Rubin, Michael (Berkeley, CA)

    2000-01-01T23:59:59.000Z

    The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

  6. Group III-nitride thin films grown using MBE and bismuth

    DOE Patents [OSTI]

    Kisielowski, Christian K. (Piedmont, CA); Rubin, Michael (Berkeley, CA)

    2002-01-01T23:59:59.000Z

    The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

  7. Evaluation and silicon nitride internal combustion engine components. Final report, Phase I

    SciTech Connect (OSTI)

    Voldrich, W. [Allied-Signal Aerospace Co., Torrance, CA (United States). Garrett Ceramic Components Div.

    1992-04-01T23:59:59.000Z

    The feasibility of silicon nitride (Si{sub 3}N{sub 4}) use in internal combustion engines was studied by testing three different components for wear resistance and lower reciprocating mass. The information obtained from these preliminary spin rig and engine tests indicates several design changes are necessary to survive high-stress engine applications. The three silicon nitride components tested were valve spring retainers, tappet rollers, and fuel pump push rod ends. Garrett Ceramic Components` gas-pressure sinterable Si{sub 3}N{sub 4} (GS-44) was used to fabricate the above components. Components were final machined from densified blanks that had been green formed by isostatic pressing of GS-44 granules. Spin rig testing of the valve spring retainers indicated that these Si{sub 3}N{sub 4} components could survive at high RPM levels (9,500) when teamed with silicon nitride valves and lower spring tension than standard titanium components. Silicon nitride tappet rollers showed no wear on roller O.D. or I.D. surfaces, steel axles and lifters; however, due to the uncrowned design of these particular rollers the cam lobes indicated wear after spin rig testing. Fuel pump push rod ends were successful at reducing wear on the cam lobe and rod end when tested on spin rigs and in real-world race applications.

  8. Light emission from silicon-rich nitride nanostructures L. Dal Negro,a

    E-Print Network [OSTI]

    Light emission from silicon-rich nitride nanostructures L. Dal Negro,a J. H. Yi, and L. C-infrared emission, large absorption/ emission Stokes shift, and nanosecond recombination. Our results are supported a crucial role in the emission mechanism of SRN films. Light emission from SRN systems can provide

  9. Free Electron Laser Nitriding of Metals: From basis physics to industrial applications

    E-Print Network [OSTI]

    Rapin, Gerd

    Accelerator Facility, Free Electron Laser Group, Newport News, VA 23606, USA Abstract Titanium was laser-liquid interface energy and the strain. Further in- vestigations showed that the dendritic growth is beginning treatment, laser nitriding, titanium PACS: 81.65.Lp, 52.50.Jm, 61.80.Ba, 76.80.+y 1 Introduction Titanium

  10. Graphene field-effect transistors based on boron nitride gate dielectrics Inanc Meric1

    E-Print Network [OSTI]

    Shepard, Kenneth

    Graphene field-effect transistors based on boron nitride gate dielectrics Inanc Meric1 , Cory Dean1, 10027 Tel: (212) 854-2529, Fax: (212) 932-9421, Email: shepard@ee.columbia.edu Abstract Graphene field of graphene, as the gate dielectric. The devices ex- hibit mobility values exceeding 10,000 cm2 /V

  11. Disordered graphene and boron nitride in a microwave tight-binding analogue S. Barkhofen,1

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Disordered graphene and boron nitride in a microwave tight-binding analogue S. Barkhofen,1 M Sophia-Antipolis, 06108 Nice, France (Dated: December 20, 2012) Experiments on hexagonal graphene of the high flexibility of the discs positions, consequences of the disorder introduced in the graphene

  12. Characterization of multilayer nitride coatings by electron microscopy and modulus mapping

    SciTech Connect (OSTI)

    Pemmasani, Sai Pramod [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P.O., Hyderabad — 500005 India (India); School of Engineering Sciences and Technology, University of Hyderabad, Gachibowli, Hyderabad — 500046 India (India); Rajulapati, Koteswararao V. [School of Engineering Sciences and Technology, University of Hyderabad, Gachibowli, Hyderabad — 500046 India (India); Ramakrishna, M.; Valleti, Krishna [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P.O., Hyderabad — 500005 India (India); Gundakaram, Ravi C., E-mail: ravi.gundakaram@arci.res.in [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P.O., Hyderabad — 500005 India (India); Joshi, Shrikant V. [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P.O., Hyderabad — 500005 India (India)

    2013-07-15T23:59:59.000Z

    This paper discusses multi-scale characterization of physical vapour deposited multilayer nitride coatings using a combination of electron microscopy and modulus mapping. Multilayer coatings with a triple layer structure based on TiAlN and nanocomposite nitrides with a nano-multilayered architecture were deposited by Cathodic arc deposition and detailed microstructural studies were carried out employing Energy Dispersive Spectroscopy, Electron Backscattered Diffraction, Focused Ion Beam and Cross sectional Transmission Electron Microscopy in order to identify the different phases and to study microstructural features of the various layers formed as a result of the deposition process. Modulus mapping was also performed to study the effect of varying composition on the moduli of the nano-multilayers within the triple layer coating by using a Scanning Probe Microscopy based technique. To the best of our knowledge, this is the first attempt on modulus mapping of cathodic arc deposited nitride multilayer coatings. This work demonstrates the application of Scanning Probe Microscopy based modulus mapping and electron microscopy for the study of coating properties and their relation to composition and microstructure. - Highlights: • Microstructure of a triple layer nitride coating studied at multiple length scales. • Phases identified by EDS, EBSD and SAED (TEM). • Nanolayered, nanocomposite structure of the coating studied using FIB and TEM. • Modulus mapping identified moduli variation even in a nani-multilayer architecture.

  13. Atmospheric ageing of nanosized silicon nitride powders Janos Szepvolgyi,*a

    E-Print Network [OSTI]

    Gubicza, Jenõ

    . Introduction Silicon nitride powders produced in high temperature thermal plasmas by the vapour phase reaction of silicon tetrachloride and ammonia have many interesting properties including high purity, mainly amorphous powders subjected to atmospheric ageing, including amino, hydroxy and silanol groups, adsorbed CO2

  14. Method for Improving Mg Doping During Group-III Nitride MOCVD

    DOE Patents [OSTI]

    Creighton, J. Randall (Albuquerque, NM); Wang, George T. (Albuquerque, NM)

    2008-11-11T23:59:59.000Z

    A method for improving Mg doping of Group III-N materials grown by MOCVD preventing condensation in the gas phase or on reactor surfaces of adducts of magnesocene and ammonia by suitably heating reactor surfaces between the location of mixing of the magnesocene and ammonia reactants and the Group III-nitride surface whereon growth is to occur.

  15. Characterization of the nitrogen split interstitial defect in wurtzite aluminum nitride using density functional theory

    SciTech Connect (OSTI)

    Szállás, A., E-mail: szallas.attila@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Szász, K. [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Institute of Physics, Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary); Trinh, X. T.; Son, N. T.; Janzén, E. [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Gali, A., E-mail: gali.adam@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest (Hungary)

    2014-09-21T23:59:59.000Z

    We carried out Heyd-Scuseria-Ernzerhof hybrid density functional theory plane wave supercell calculations in wurtzite aluminum nitride in order to characterize the geometry, formation energies, transition levels, and hyperfine tensors of the nitrogen split interstitial defect. The calculated hyperfine tensors may provide useful fingerprint of this defect for electron paramagnetic resonance measurement.

  16. LPCVD SILICON NITRIDE-ON-SILICON SPACER TECHNOLOGY H. W. van Zeijl, L.K. Nanver

    E-Print Network [OSTI]

    Technische Universiteit Delft

    of obtaining self-aligned sub- lithographic dimensions. In many processes were spacers are applied to separate-etching affects the dimensions of the spacer which could lead to a lack of control over the spacer-related deviceLPCVD SILICON NITRIDE-ON-SILICON SPACER TECHNOLOGY H. W. van Zeijl, L.K. Nanver DIMES Delft

  17. Base-contact proximity effects in bipolar transistors with nitride-spacer technology

    E-Print Network [OSTI]

    Technische Universiteit Delft

    -lithographic dimensions. For example, in the double polysilicon bipolar transistor, spacers are used to separate the baseBase-contact proximity effects in bipolar transistors with nitride-spacer technology Henk van Zeijl-BJT's with spacer separated Al/Si emitter and base contacts are fabricated and characterized. Due to the proximity

  18. CO-IMPLANTATION AND DRY-ETCH DAMAGE RECOVERY BY PLASMA NITRIDATION IN GaN

    E-Print Network [OSTI]

    Pearton, Stephen J.

    CO-IMPLANTATION AND DRY-ETCH DAMAGE RECOVERY BY PLASMA NITRIDATION IN GaN BY DONALD G. KENT III ............................................................................ x CHAPTERS 1 INTRODUCTION ................................................................. 1 1.1 GaN Applications ........................................................ 1 1.2 GaN Material Issues

  19. ELECTRON MICROPROBE AND PHOTOLUMINESCENCE ANALYSIS OF EUROPIUM-DOPED GALLIUM NITRIDE LIGHT EMITTERS

    E-Print Network [OSTI]

    Strathclyde, University of

    ELECTRON MICROPROBE AND PHOTOLUMINESCENCE ANALYSIS OF EUROPIUM-DOPED GALLIUM NITRIDE LIGHT EMITTERSN-on-sapphire epilayers implanted with Europium ions, producing characteristic red emission lines between 540 and 680 nm with energies largely independent of the host material. For example, doping with europium, erbium and thulium

  20. Process for preparing a densified beta-phase silicon nitride material having at least one densification aid, and the material resulting therefrom

    SciTech Connect (OSTI)

    Edler, J.P.; Lisowsky, B.

    1993-05-25T23:59:59.000Z

    A process is described for preparing an alpha-phase silicon nitride material and thereafter sintering to a densified beta-phase silicon nitride material, comprising: (a) comminuting a slurry including a mixture of (i) silicon-containing powder, (ii) water, and (iii) at least one densification aid to aid in later densifying of the silicon nitride material, said comminuting being performed to form fresh, non-oxidized surfaces on the silicon powder and to allow substantial chemical reaction between the silicon and the water, said comminuting being performed to form fresh, non-oxidized surfaces on the silicon powder and to allow substantial chemical reaction between the silicon and the water, yielding a mass; (b) nitriding the mass by exposure to a sufficient amount of a nitriding gas including at least nitrogen at a sufficient temperature for a sufficient length of time to form a mass of substantially alpha-phase silicon nitride; and (c) sintering the resultant silicon nitride mass at a sintering holding temperature of from about 1,450 C to about 2,100 C for a sufficient length of time to convert the silicon nitride from a predominantly alpha-phase material to a predominantly densified beta phase silicon nitride material exhibiting a decrease in bulk volume of the silicon nitride due to the densification.

  1. Additive-assisted synthesis of boride, carbide, and nitride micro/nanocrystals

    SciTech Connect (OSTI)

    Chen, Bo [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China); Yang, Lishan [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Shandong University), Ministry of Education, and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)] [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Shandong University), Ministry of Education, and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Heng, Hua; Chen, Jingzhong; Zhang, Linfei; Xu, Liqiang [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China); Qian, Yitai, E-mail: ytqian@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China); Yang, Jian, E-mail: yangjian@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)] [Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, and Department of Chemistry, Shandong University, Jinan 250100 (China)

    2012-10-15T23:59:59.000Z

    General and simple methods for the syntheses of borides, carbides and nitrides are highly desirable, since those materials have unique physical properties and promising applications. Here, a series of boride (TiB{sub 2}, ZrB{sub 2}, NbB{sub 2}, CeB{sub 6}, PrB{sub 6}, SmB{sub 6}, EuB{sub 6}, LaB{sub 6}), carbide (SiC, TiC, NbC, WC) and nitride (TiN, BN, AlN, MgSiN{sub 2}, VN) micro/nanocrystals were prepared from related oxides and amorphous boron/active carbon/NaN{sub 3} with the assistance of metallic Na and elemental S. In-situ temperature monitoring showed that the reaction temperature could increase quickly to {approx}850 Degree-Sign C, once the autoclave was heated to 100 Degree-Sign C. Such a rapid temperature increase was attributed to the intense exothermic reaction between Na and S, which assisted the formation of borides, carbides and nitrides. The as-obtained products were characterized by XRD, SEM, TEM, and HRTEM techniques. Results in this report will greatly benefit the future extension of this approach to other compounds. - Graphical abstract: An additive-assisted approach is successfully developed for the syntheses of borides, carbides and nitrides micro/nanocrystals with the assistance of the exothermic reaction between Na and S. Highlights: Black-Right-Pointing-Pointer An additive-assisted synthesis strategy is developed for a number of borides, carbides and nitrides. Black-Right-Pointing-Pointer The reaction mechanism is demonstrated by the case of SiC nanowires. Black-Right-Pointing-Pointer The formation of SiC nanowires is initiated by the exothermic reaction of Na and S.

  2. Sampling diffusive transition paths

    E-Print Network [OSTI]

    F. Miller III, Thomas

    2009-01-01T23:59:59.000Z

    Sampling di?usive transition paths Thomas F. Miller III ?the algorithm to sample the transition path ensemble for thedynamics I. INTRODUCTION Transition path sampling (TPS) is a

  3. Aluminum nitride transitional layer for reducing dislocation density and cracking of AlGaN epitaxial films

    DOE Patents [OSTI]

    Allerman, Andrew A.; Crawford, Mary H.; Lee, Stephen R.

    2013-01-08T23:59:59.000Z

    A denticulated Group III nitride structure that is useful for growing Al.sub.xGa.sub.1-xN to greater thicknesses without cracking and with a greatly reduced threading dislocation (TD) density.

  4. Using Monte Carlo ray tracing simulations to model the quantum harmonic oscillator modes observed in uranium nitride

    SciTech Connect (OSTI)

    Lin, J. Y. Y. [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Aczel, Adam A [ORNL] [ORNL; Abernathy, Douglas L [ORNL] [ORNL; Nagler, Stephen E [ORNL] [ORNL; Buyers, W. J. L. [National Research Council of Canada] [National Research Council of Canada; Granroth, Garrett E [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    Recently an extended series of equally spaced vibrational modes was observed in uranium nitride (UN) by performing neutron spectroscopy measurements using the ARCS and SEQUOIA time-of- flight chopper spectrometers [A.A. Aczel et al, Nature Communications 3, 1124 (2012)]. These modes are well described by 3D isotropic quantum harmonic oscillator (QHO) behavior of the nitrogen atoms, but there are additional contributions to the scattering that complicate the measured response. In an effort to better characterize the observed neutron scattering spectrum of UN, we have performed Monte Carlo ray tracing simulations of the ARCS and SEQUOIA experiments with various sample kernels, accounting for the nitrogen QHO scattering, contributions that arise from the acoustic portion of the partial phonon density of states (PDOS), and multiple scattering. These simulations demonstrate that the U and N motions can be treated independently, and show that multiple scattering contributes an approximate Q-independent background to the spectrum at the oscillator mode positions. Temperature dependent studies of the lowest few oscillator modes have also been made with SEQUOIA, and our simulations indicate that the T-dependence of the scattering from these modes is strongly influenced by the uranium lattice.

  5. A study into effects of CO{sub 2} laser melting of nitrided Ti-6Al-4V alloy

    SciTech Connect (OSTI)

    Mohammed, M.A. [Saudi Aramco, Dhahran (Saudi Arabia); Hashmi, M.S.J. [Dublin City Univ. (Ireland); Yilbas, B.S. [KFDUPM, Dhahran (Saudi Arabia)

    1997-10-01T23:59:59.000Z

    Multiple treatment of engineering surfaces can provide improved surface properties that cannot be obtained by a single surface treatment. Consequently, this study investigates the effects of laser melting on the microstructures of plasma nitrided Ti-6Al-4V alloy. The study consists of two parts. In the first part, governing equations pertinent to the laser melting process are developed, and temperature variation across the melted zone is predicted. In the second, an experiment is conducted to nitride the surface of the alloy through plasma nitriding process and to melt the plasma nitrided and the untreated alloy surfaces with a CO{sub 2} laser beam. The resulting metallurgical changes are examined using x-ray diffraction (XRD), energy-dispersive spectrometry (EDS), and scanning electron microscopy (SEM) techniques. It is shown that three distinct nitride layers are formed in the vicinity of the alloy surface prior to the laser melting process, and that after the melting process nitrided species are depleted while cellular and dendritic structures are formed. In addition, the structure consisting of transformed {beta} containing coarse and fine acicular {alpha} is observed in the melted regions.

  6. Structure analysis of aluminium silicon manganese nitride precipitates formed in grain-oriented electrical steels

    SciTech Connect (OSTI)

    Bernier, Nicolas, E-mail: n.bernier@yahoo.fr [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Xhoffer, Chris [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Van De Putte, Tom, E-mail: tom.vandeputte@arcelormittal.com [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Galceran, Montserrat [Université Libre de Bruxelles, 4MAT (Materials Engineering, Characterization, Synthesis and Recycling), Avenue F.D. Roosevelt 50, 1050 Brussels (Belgium); CIC Energigune, Albert Einstein 48, 01510 Miñano (Álava) (Spain); Godet, Stéphane [Université Libre de Bruxelles, 4MAT (Materials Engineering, Characterization, Synthesis and Recycling), Avenue F.D. Roosevelt 50, 1050 Brussels (Belgium)

    2013-12-15T23:59:59.000Z

    We report a detailed structural and chemical characterisation of aluminium silicon manganese nitrides that act as grain growth inhibitors in industrially processed grain-oriented (GO) electrical steels. The compounds are characterised using energy dispersive X-ray spectrometry (EDX) and energy filtered transmission electron microscopy (EFTEM), while their crystal structures are analysed using X-ray diffraction (XRD) and TEM in electron diffraction (ED), dark-field, high-resolution and automated crystallographic orientation mapping (ACOM) modes. The chemical bonding character is determined using electron energy loss spectroscopy (EELS). Despite the wide variation in composition, all the precipitates exhibit a hexagonal close-packed (h.c.p.) crystal structure and lattice parameters of aluminium nitride. The EDX measurement of ? 900 stoichiometrically different precipitates indicates intermediate structures between pure aluminium nitride and pure silicon manganese nitride, with a constant Si/Mn atomic ratio of ? 4. It is demonstrated that aluminium and silicon are interchangeably precipitated with the same local arrangement, while both Mn{sup 2+} and Mn{sup 3+} are incorporated in the h.c.p. silicon nitride interstitial sites. The oxidation of the silicon manganese nitrides most likely originates from the incorporation of oxygen during the decarburisation annealing process, thus creating extended planar defects such as stacking faults and inversion domain boundaries. The chemical composition of the inhibitors may be written as (AlN){sub x}(SiMn{sub 0.25}N{sub y}O{sub z}){sub 1?x} with x ranging from 0 to 1. - Highlights: • We study the structure of (Al,Si,Mn)N inhibitors in grain oriented electrical steels. • Inhibitors have the hexagonal close-packed symmetry with lattice parameters of AlN. • Inhibitors are intermediate structures between pure AlN and (Si,Mn)N with Si/Mn ? 4. • Al and Si share the same local arrangement; Mn is incorporated in both Mn{sup 2+} and Mn{sup 3+}. • Oxygen incorporation is invoked to account for the thermal stability of (Al,Si,Mn)N.

  7. 1100/,,1102... twin boundaries in wurtzite ZnO and group-III-nitrides Yanfa Yan and M. M. Al-Jassim

    E-Print Network [OSTI]

    Pennycook, Steve

    11¯00/,,1102... twin boundaries in wurtzite ZnO and group-III-nitrides Yanfa Yan and M. M. Al that the same twin boundaries in wurtzite group-III-nitrides adopt the same structure, but the twin states in the band gap in either ZnO or the wurtzite group-III-nitrides. DOI: 10.1103/PhysRevB.71

  8. Thermal transport in boron nitride nanotorus—towards a nanoscopic thermal shield

    SciTech Connect (OSTI)

    Loh, G. C., E-mail: jgloh@mtu.edu [Institute of High Performance Computing, 1 Fusionopolis Way, 16-16 Connexis, Singapore 138632 (Singapore); Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Baillargeat, D. [CNRS-International-NTU-Thales Research Alliance (CINTRA), 50 Nanyang Drive, Singapore 637553 (Singapore)

    2013-11-14T23:59:59.000Z

    Nanotori, or nanorings, are topological variants of nanotubes and are conceived to have different properties from their tubular form. In this study, the toroidal arrangement of boron nitride is introduced. Using classical molecular dynamics simulations, the thermal behaviour (thermal conductivity and thermal stability) of the boron nitride nanotorus and its relationship with the structural characteristics are investigated. Its circumferential thermal rectification strength displays a linear dependence on the bending coefficient of the nanostructure. Surface kinks are relatively inconsequential on its circumferential mode of conduction, as compared to its axial sense. The circumferential conductivity in the diffusive regime is calculated to be approximately 10?W/m K, while the axial conductivity is more than tenfold of this value. All nanotori with different toroidal characters show excellent thermal stability at extremely high temperatures approaching 3400?K. With consideration to its favourable properties, a thermal shield made up of a parallel row of nanotori is proposed as a nanoscale thermal insulation device.

  9. The Durability of Various Crucible Materials for Aluminum Nitride Crystal growth by Sublimation

    SciTech Connect (OSTI)

    Liu,B.; Edgar, J.; Gu, Z.; Zhuang, D.; Raghothamachar, B.; Dudley, M.; Sarua, A.; Kuball, M.; Meyer, H.

    2004-01-01T23:59:59.000Z

    Producing high purity aluminum nitride crystals by the sublimation-recondensation technique is difficult due to the inherently reactive crystal growth environment, normally at temperature in excess of 2100 C. The durability of the furnace fixture materials (crucibles, retorts, etc.) at such a high temperature remains a critical problem. In the present study, the suitability of several refractory materials for AlN crystal growth is investigated, including tantalum carbide, niobium carbide, tungsten, graphite, and hot-pressed boron nitride. The thermal and chemical properties and performance of these materials in inert gas, as well as under AlN crystal growth conditions are discussed. TaC and NbC are the most stable crucible materials with very low elemental vapor pressures in the crystal growth system. Compared with refractory material coated graphite crucibles, HPBN crucible is better for AlN self-seeded growth, as crystals tend to nucleate in thin colorless platelets with low dislocation density.

  10. High density hexagonal boron nitride prepared by hot isostatic pressing in refractory metal containers

    DOE Patents [OSTI]

    Hoenig, Clarence L. (Livermore, CA)

    1992-01-01T23:59:59.000Z

    Boron nitride powder with less than or equal to the oxygen content of starting powder (down to 0.5% or less) is hot isostatically pressed in a refractory metal container to produce hexagonal boron nitride with a bulk density greater than 2.0 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed or chemical vapor deposited onto a powder compact. Hot isostatic pressing at 1800.degree. C. and 30 KSI (206.8 MPa) argon pressure for four hours produces a bulk density of 2.21 g/cc. Complex shapes can be made.

  11. Phase transformations of nano-sized cubic boron nitride to white graphene and white graphite

    SciTech Connect (OSTI)

    Dang, Hongli; Liu, Yingdi; Xue, Wenhua; Anderson, Ryan S.; Sewell, Cody R. [Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, Oklahoma 74104 (United States); Xue, Sha; Crunkleton, Daniel W. [Department of Chemical Engineering, The University of Tulsa, Tulsa, Oklahoma 74104 (United States); Institute of Alternate Energy, The University of Tulsa, Tulsa, Oklahoma 74104 (United States); Shen, Yaogen [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon (Hong Kong); Wang, Sanwu, E-mail: sanwu-wang@utulsa.edu [Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, Oklahoma 74104 (United States); Institute of Alternate Energy, The University of Tulsa, Tulsa, Oklahoma 74104 (United States)

    2014-03-03T23:59:59.000Z

    We report quantum-mechanical investigations that predict the formation of white graphene and nano-sized white graphite from the first-order phase transformations of nano-sized boron nitride thin-films. The phase transformations from the nano-sized diamond-like structure, when the thickness d?>?1.4?nm, to the energetically more stable nano-sized white graphite involve low activation energies of less than 1.0?eV. On the other hand, the diamond-like structure transforms spontaneously to white graphite when d???1.4?nm. In particular, the two-dimensional structure with single-layer boron nitride, the so-called white graphene, could be formed as a result of such transformation.

  12. Amber light-emitting diode comprising a group III-nitride nanowire active region

    DOE Patents [OSTI]

    Wang, George T.; Li, Qiming; Wierer, Jr., Jonathan J.; Koleske, Daniel

    2014-07-22T23:59:59.000Z

    A temperature stable (color and efficiency) III-nitride based amber (585 nm) light-emitting diode is based on a novel hybrid nanowire-planar structure. The arrays of GaN nanowires enable radial InGaN/GaN quantum well LED structures with high indium content and high material quality. The high efficiency and temperature stable direct yellow and red phosphor-free emitters enable high efficiency white LEDs based on the RGYB color-mixing approach.

  13. Integrated rig for the production of boron nitride nanotubes via the pressurized vapor-condenser method

    DOE Patents [OSTI]

    Smith, Michael W; Jordan, Kevin C

    2014-03-25T23:59:59.000Z

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  14. Dispersion engineered high-Q silicon Nitride Ring-Resonators via Atomic Layer Deposition

    E-Print Network [OSTI]

    Riemensberger, Johann; Herr, Tobias; Brasch, Victor; Holzwarth, Ronald; Kippenberg, Tobias J

    2012-01-01T23:59:59.000Z

    We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition (ALD). Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. All results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

  15. Ligand-Based Reduction of CO2 to CO Mediated by an Anionic Niobium Nitride Complex

    E-Print Network [OSTI]

    Silvia, Jared Scott

    The terminal nitride anion complex [Na][N?Nb(N[tBu]Ar)3] ([Na][1], Ar = 3,5-Me2C6H3) reacts quantitatively with CO2 to give the carbamate complex [Na][O2CN?Nb(N[tBu]Ar)3] ([Na][O2C-1]). The structure of [Na][O2C-1] as the ...

  16. Use of free silicon in liquid phase sintering of silicon nitrides and sialons

    DOE Patents [OSTI]

    Raj, R.; Baik, S.

    1985-11-12T23:59:59.000Z

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

  17. Use of free silicon in liquid phase sintering of silicon nitrides and sialons

    DOE Patents [OSTI]

    Raj, Rishi (Ithaca, NY); Baik, Sunggi (Ithaca, NY)

    1985-11-12T23:59:59.000Z

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

  18. Ab initio study of phase transition of boron nitride between zinc-blende and rhombohedral structures

    SciTech Connect (OSTI)

    Nishida, S.; Funashima, H.; Sato, K.; Katayama-Yoshida, H. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2013-12-04T23:59:59.000Z

    Boron nitride has polymorphs such as zinc-blende (c-BN), wurtzite (w-BN), rhombohedral (r-BN), and graphite-like (h-BN) forms. We simulate the direct conversion of r-BN to c-BN through electronic excitation. In our calculation, the conversion is made possible by increasing the hole concentration to over 0.06/atom. This conversion should be experimentally possible by hole-doping via an electric double layer transistor (EDLT) or capacitor.

  19. Partitioning of fission products from irradiated nitride fuel using inductive vaporization

    SciTech Connect (OSTI)

    Shcherbina, N.; Kulik, D.A.; Kivel, N.; Potthast, H.D.; Guenther-Leopold, I. [Paul Scherrer Institut - PSI, Villigen 5232 (Switzerland)

    2013-07-01T23:59:59.000Z

    Irradiated nitride fuel (Pu{sub 0.3}Zr{sub 0.7})N fabricated at PSI in frame of the CONFIRM project and having a burn-up of 10.4 % FIMA (Fission per Initial Metal Atom) has been investigated by means of inductive vaporization. The study of thermal stability and release behavior of Pu, Am, Zr and fission products (FPs) was performed in a wide temperature range (up to 2300 C. degrees) and on different redox conditions. On-line monitoring by ICP-MS detected low nitride stability and significant loss of Pu and Am at T>1900 C. degrees during annealing under inert atmosphere (Ar). The oxidative pre-treatment of nitride fuel on air at 1000 C. degrees resulted in strong retention of Pu and Am in the solid, as well as of most FPs. Thermodynamic modelling of elemental speciation using GEM-Selektor v.3 code (Gibbs Energy Minimization Selektor), supported by a comprehensive literature review on thermodynamics of actinides and FPs, revealed a number of binary compounds of Cs, Mo, Te, Sr and Ba to occur in the solid. Speciation of some FPs in the fuel is discussed and compared to earlier results of electron probe microanalysis (EPMA). Predominant vapor species predicted by GEM-Selektor calculations were Pu(g), Am(g) and N{sub 2}. Nitrogen can be completely released from the fuel after complete oxidation at 1000 C. degrees. With regard to the irradiated nitride reprocessing technology, this result can have an important practical application as an alternative way for {sup 15}N recovery. (authors)

  20. IMPROVEMENT OF CRYSTALLINE QUALITY OF GROUP III NITRIDES ON SAPPHIRE USING LOW TEMPERATURE INTERLAYERS

    E-Print Network [OSTI]

    Wetzel, Christian M.

    cm-2 that originate at the interface between GaN and the LT-BL and/or sapphire substrate [9,10]. TDs sapphire substrate and HT-GaN is called buffer layer (BL), while the LT-layer between HT-nitride is called on the sapphire substrate. The thickness was ~20nm. HT-GaN was grown at 1,050°C on the LT-BL. The thickness

  1. Direct measurement of the reactivity of NH and OH on a silicon nitride surface

    SciTech Connect (OSTI)

    Buss, R.J.; Ho, P.; Breiland, W.G. [Sandia National Labs., Albuquerque, NM (United States); Fisher, E.R. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Chemistry

    1993-12-31T23:59:59.000Z

    In order to understand and successfully model the plasma processing used in device fabrication, it is important to determine the role played by plasma-generated radicals. The authors have used the IRIS technique (Imaging of Radicals Interacting Surfaces) to obtain the reactivity of NH (X{sup 3}S{sup {minus}}) and OH (X{sup 2}P) at a silicon nitride film surface while the film is exposed to a plasma-type environment. The reactivity of NH was found to be zero both during exposure of the surface to an NH{sub 3} plasma and during active deposition of silicon nitride from a SiH{sub 4}/NH{sub 3} plasma. No NH surface reaction was detectable for any rotational states of NH and over a surface temperature range of 300--700 K. OH radicals generated in an H{sub 2}O plasma were found to have a reactivity of 0.57 on a room temperature oxidized silicon nitride surface. The OH reactivity falls to zero as the temperature of the substrate is raised.

  2. MOCVD synthesis of group III-nitride heterostructure nanowires for solid-state lighting.

    SciTech Connect (OSTI)

    Wang, George T.; Creighton, James Randall; Talin, Albert Alec

    2006-11-01T23:59:59.000Z

    Solid-state lighting (SSL) technologies, based on semiconductor light emitting devices, have the potential to reduce worldwide electricity consumption by more than 10%, which could significantly reduce U.S. dependence on imported energy and improve energy security. The III-nitride (AlGaInN) materials system forms the foundation for white SSL and could cover a wide spectral range from the deep UV to the infrared. For this LDRD program, we have investigated the synthesis of single-crystalline III-nitride nanowires and heterostructure nanowires, which may possess unique optoelectronic properties. These novel structures could ultimately lead to the development of novel and highly efficient SSL nanodevice applications. GaN and III-nitride core-shell heterostructure nanowires were successfully synthesized by metal organic chemical vapor deposition (MOCVD) on two-inch wafer substrates. The effect of process conditions on nanowire growth was investigated, and characterization of the structural, optical, and electrical properties of the nanowires was also performed.

  3. Transmission electron microscopy investigation of acicular ferrite precipitation in {gamma}'-Fe{sub 4}N nitride

    SciTech Connect (OSTI)

    Xiong, X.C., E-mail: xiaochuan.xiong@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Institut Jean Lamour, UMR 7198 CNRS, Nancy-Universite, UPV-Metz, Ecole des Mines de Nancy, Parc de Saurupt CS 14234, F-54042 Nancy Cedex (France); Redjaimia, A. [Institut Jean Lamour, UMR 7198 CNRS, Nancy-Universite, UPV-Metz, Ecole des Mines de Nancy, Parc de Saurupt CS 14234, F-54042 Nancy Cedex (France); Goune, M. [Institut Jean Lamour, UMR 7198 CNRS, Nancy-Universite, UPV-Metz, Ecole des Mines de Nancy, Parc de Saurupt CS 14234, F-54042 Nancy Cedex (France); ArcelorMittal SA, Voie Romaine, BP 30320, F-57283 Maizieres-les-Metz (France)

    2010-11-15T23:59:59.000Z

    Acicular-shaped crystals precipitate from {gamma}'-Fe{sub 4}N nitride in an iron-nitrogen alloy and were identified by electron microdiffraction as {alpha}-ferrite. Acicular ferrite develops both the Nishiyama-Wassermann and the Kurdjumov-Sachs orientation relationships with {gamma}'-Fe{sub 4}N nitride. These orientation relationships were discussed in terms of the symmetry theory. The driving force for acicular ferrite formation was related to the increasing nitrogen content of {gamma}'-Fe{sub 4}N, in equilibrium with {alpha}-ferrite, with decreasing temperature. The passage from lamellar to acicular structure in Fe-N system was proposed. - Research Highlights: {yields} Acicular crystals precipitate from pearlitic{gamma}'-Fe{sub 4}N nitride in an iron-nitrogen alloy and were identified by electron microdiffraction as acicular ferrite. {yields} The crystal structure, orientation relationships with the matrix and morphologies of acicular ferrite, were studied by transmission electron microscopy. {yields} The driving force for the formation of acicular ferrite is related to the temperature dependence of nitrogen content of {gamma}'-Fe{sub 4}N, in equilibrium with ferrite. {yields} The passage from the pearlitic structure to the acicular structure in the present iron-nitrogen alloy was proposed.

  4. Behavior of molybdenum nitrides as materials for electrochemical capacitors: Comparison with ruthenium oxide

    SciTech Connect (OSTI)

    Liu, T.C.; Pell, W.G.; Conway, B.E. [Univ. of Ottawa, Ontario (Canada). Dept. of Chemistry; Roberson, S.L. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering

    1998-06-01T23:59:59.000Z

    Ruthenium oxide (RuO{sub 2}), formed as a thin film on a Ru or Ti metal substrate, exhibits a large specific (cm{sup {minus}2}) and almost constant, electrochemical capacitance over a 1.35 V range in aqueous H{sub 2}SO{sub 4}. This behavior has led to its investigation and use as a material for fabrication of supercapacitor devices. However, its cost has encouraged search for other materials exhibiting similar behavior. Work reported in the present paper evaluates two nitrides of Mo, Mo{sub 2}N and MoN, as substitutes for RuO{sub 2}. It is shown that very similar capacitance behavior to that of RuO{sub 2} films arises, e.g., in cyclic voltammetry and dc charging curves; in the former, almost mirror-image anodic and cathodic current-response profiles, characteristic of a capacitor, arise. However, the nitride materials have a substantially smaller voltage operating range of only some 0.7 V due to electrochemical decomposition above ca. 0.7 V vs. RHE. This limits their usefulness as a substitute for RuO{sub 2}. Of interest is that the nitride films exhibit potential-decay and potential-recovery on open circuit after respective charge and forced discharge. The decay and recovery processes are logarithmic in time, indicating the role of internal faradaic charge redistribution processes.

  5. Epitaxial GaN films by hyperthermal ion-beam nitridation of Ga droplets

    SciTech Connect (OSTI)

    Gerlach, J. W.; Ivanov, T.; Neumann, L.; Hoeche, Th.; Hirsch, D.; Rauschenbach, B. [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), D-04318 Leipzig (Germany)

    2012-06-01T23:59:59.000Z

    Epitaxial GaN film formation on bare 6H-SiC(0001) substrates via the process of transformation of Ga droplets into a thin GaN film by applying hyperthermal nitrogen ions is investigated. Pre-deposited Ga atoms in well defined amounts form large droplets on the substrate surface which are subsequently nitridated at a substrate temperature of 630 Degree-Sign C by a low-energy nitrogen ion beam from a constricted glow-discharge ion source. The Ga deposition and ion-beam nitridation process steps are monitored in situ by reflection high-energy electron diffraction. Ex situ characterization by x-ray diffraction and reflectivity techniques, Rutherford backscattering spectrometry, and electron microscopy shows that the thickness of the resulting GaN films depends on the various amounts of pre-deposited gallium. The films are epitaxial to the substrate, exhibit a mosaic like, smooth surface topography and consist of coalesced large domains of low defect density. Possible transport mechanisms of reactive nitrogen species during hyperthermal nitridation are discussed and the formation of GaN films by an ion-beam assisted process is explained.

  6. Role of Ion Damage on Unintentional Ca Incorporation During the Plasma-Assisted Molecular-Beam Epitaxy Growth of Dilute Nitrides Using N2/Ar Source Gas Mixtures

    SciTech Connect (OSTI)

    Oye, M. M.; Bank, S. R.; Ptak, A. J.; Reedy, R. C.; Goorsky, M. S.; Holmes Jr., A. L.

    2008-05-01T23:59:59.000Z

    Unintentional Ca incorporation caused by Ca-contaminated substrate surfaces on as-purchased GaAs wafers are known to limit the efficiency of solar cells based on dilute nitride materials. This article focuses on further understanding the conditions and mechanisms by which these Ca impurities incorporate. Plasma-assisted molecular-beam epitaxy utilizing a 1% N{sub 2} in Ar precursor gas mixture was used to grow GaAs at 400 and 580 C, and GaN{sub 0.01}As{sub 0.99} at 400 C. Two plasma operating combinations of rf power and gas flow rate were used to generate different amounts and energies of both ions and other plasma species, while keeping nitrogen incorporation constant. The ions were characterized with a dual-grid, retarding-field ion energy analyzer, and the corresponding ion energy distributions are presented to correlate ions with Ca incorporation. When appropriate, dc-biased deflector plates were used to remove ions during growth. Secondary ion mass spectrometry was used to measure Ca in GaAs and GaN{sub 0.01}As{sub 0.99}. Ca incorporation was observed in the dilute nitride samples, but the effects of ions did not exceed other Ca incorporation mechanisms associated with defects due to both low temperature growth and nitrogen incorporation; however, different neutral active nitrogen species (atomic N and metastable N{sub 2}) may be a factor. Ca incorporation measured in GaAs grown at 400 C with a pure Ar plasma is predominantly due to defects associated with low temperature growth, as opposed to plasma damage caused by the ions. GaAs growths at 580 C without a plasma did not exhibit Ca incorporation, but growth at 580 C with ions from a pure Ar plasma caused Ca incorporation.

  7. Analytical and experimental evaluation of joining silicon carbide to silicon carbide and silicon nitride to silicon nitride for advanced heat engine applications Phase 2. Final report

    SciTech Connect (OSTI)

    Sundberg, G.J.; Vartabedian, A.M.; Wade, J.A.; White, C.S. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.

    1994-10-01T23:59:59.000Z

    The purpose of joining, Phase 2 was to develop joining technologies for HIP`ed Si{sub 3}N{sub 4} with 4wt% Y{sub 2}O{sub 3} (NCX-5101) and for a siliconized SiC (NT230) for various geometries including: butt joins, curved joins and shaft to disk joins. In addition, more extensive mechanical characterization of silicon nitride joins to enhance the predictive capabilities of the analytical/numerical models for structural components in advanced heat engines was provided. Mechanical evaluation were performed by: flexure strength at 22 C and 1,370 C, stress rupture at 1,370 C, high temperature creep, 22 C tensile testing and spin tests. While the silicon nitride joins were produced with sufficient integrity for many applications, the lower join strength would limit its use in the more severe structural applications. Thus, the silicon carbide join quality was deemed unsatisfactory to advance to more complex, curved geometries. The silicon carbide joining methods covered within this contract, although not entirely successful, have emphasized the need to focus future efforts upon ways to obtain a homogeneous, well sintered parent/join interface prior to siliconization. In conclusion, the improved definition of the silicon carbide joining problem obtained by efforts during this contract have provided avenues for future work that could successfully obtain heat engine quality joins.

  8. ESPC IDIQ Contract Sample

    Broader source: Energy.gov [DOE]

    Document displays a sample indefinite delivery, indefinite quantity (IDIQ) energy savings performance contract (ESPC).

  9. Power mixture and green body for producing silicon nitride base articles of high fracture toughness and strength

    DOE Patents [OSTI]

    Huckabee, M.L.; Buljan, S.T.; Neil, J.T.

    1991-09-17T23:59:59.000Z

    A powder mixture and a green body for producing a silicon nitride-based article of improved fracture toughness and strength are disclosed. The powder mixture includes (a) a bimodal silicon nitride powder blend consisting essentially of about 10-30% by weight of a first silicon nitride powder of an average particle size of about 0.2 [mu]m and a surface area of about 8-12m[sup 2]g, and about 70-90% by weight of a second silicon nitride powder of an average particle size of about 0.4-0.6 [mu]m and a surface area of about 2-4 m[sup 2]/g, (b) about 10-50 percent by volume, based on the volume of the densified article, of refractory whiskers or fibers having an aspect ratio of about 3-150 and having an equivalent diameter selected to produce in the densified article an equivalent diameter ratio of the whiskers or fibers to grains of silicon nitride of greater than 1.0, and (c) an effective amount of a suitable oxide densification aid. The green body is formed from the powder mixture, an effective amount of a suitable oxide densification aid, and an effective amount of a suitable organic binder. No Drawings

  10. Aluminum Nitride Thin Films on Titanium for Piezoelectric MEMS Applications Seth Boeshore, Emily Parker, Vanni Lughi, Noel C. MacDonald

    E-Print Network [OSTI]

    MacDonald, Noel C.

    Aluminum Nitride Thin Films on Titanium for Piezoelectric MEMS Applications Seth Boeshore, Emily nitride thin films have been deposited onto titanium substrates for the purpose of fabricating piezoelectric MEMS. Titanium is a new and attractive platform for MEMS because of its corrosion resistance

  11. Role of silicon excess in Er-doped silicon-rich nitride light emitting devices at 1.54??m

    SciTech Connect (OSTI)

    Ramírez, J. M., E-mail: jmramirez@el.ub.edu; Berencén, Y.; Garrido, B. [MIND-IN2UB, Department Electrònica, Universitat de Barcelona, Martí i Franquès 1, Barcelona 08028 (Spain); Cueff, S. [Institut des Nanotechnologies de Lyon, École Centrale de Lyon, Écully 69134 (France); Labbé, C. [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CNRS/CEA/Ensicaen/UCBN, Caen 14050 (France)

    2014-08-28T23:59:59.000Z

    Erbium-doped silicon-rich nitride electroluminescent thin-films emitting at 1.54??m have been fabricated and integrated within a metal-oxide-semiconductor structure. By gradually varying the stoichiometry of the silicon nitride, we uncover the role of silicon excess on the optoelectronic properties of devices. While the electrical transport is mainly enabled in all cases by Poole-Frenkel conduction, power efficiency and conductivity are strongly altered by the silicon excess content. Specifically, the increase in silicon excess remarkably enhances the conductivity and decreases the charge trapping; however, it also reduces the power efficiency. The main excitation mechanism of Er{sup 3+} ions embedded in silicon-rich nitrides is discussed. The optimum Si excess that balances power efficiency, conductivity, and charge trapping density is found to be close to 16%.

  12. Rain sampling device

    DOE Patents [OSTI]

    Nelson, D.A.; Tomich, S.D.; Glover, D.W.; Allen, E.V.; Hales, J.M.; Dana, M.T.

    1991-05-14T23:59:59.000Z

    The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of the precipitation from the chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device. 11 figures.

  13. Rain sampling device

    DOE Patents [OSTI]

    Nelson, Danny A. (Richland, WA); Tomich, Stanley D. (Richland, WA); Glover, Donald W. (Prosser, WA); Allen, Errol V. (Benton City, WA); Hales, Jeremy M. (Kennewick, WA); Dana, Marshall T. (Richland, WA)

    1991-01-01T23:59:59.000Z

    The present invention constitutes a rain sampling device adapted for independent operation at locations remote from the user which allows rainfall to be sampled in accordance with any schedule desired by the user. The rain sampling device includes a mechanism for directing wet precipitation into a chamber, a chamber for temporarily holding the precipitation during the process of collection, a valve mechanism for controllably releasing samples of said precipitation from said chamber, a means for distributing the samples released from the holding chamber into vessels adapted for permanently retaining these samples, and an electrical mechanism for regulating the operation of the device.

  14. COMPUTER SCIENCE SAMPLE PROGRAM

    E-Print Network [OSTI]

    Gering, Jon C.

    COMPUTER SCIENCE SAMPLE PROGRAM (First Math Course MATH 198) This sample program suggests one way CS 181: Foundations of Computer Science II CS 180: Foundations of Computer Science I CS 191

  15. Bonding distances as Exact Sums of the Radii of the Constituent Atoms in Nanomaterials - Boron Nitride and Coronene

    E-Print Network [OSTI]

    Raji Heyrovska

    2011-12-19T23:59:59.000Z

    This paper presents for the first time the exact structures at the atomic level of two important nanomaterials, boron nitride and coronene. Both these compounds are hexagonal layer structures similar to graphene in two dimensions and to graphite in three-dimensions. However, they have very different properties: whereas graphene is a conductor, h-BN is an electrical insulator and coronene is a polycyclic aromatic hydrocarbon of cosmological interest. The atomic structures presented here for boron nitride, coronene and graphene have been drawn to scale based on bond lengths as sums of the atomic radii.

  16. The electroluminescence mechanism of Er³? in different silicon oxide and silicon nitride environments

    SciTech Connect (OSTI)

    Rebohle, L., E-mail: l.rebohle@hzdr.de; Wutzler, R.; Braun, M.; Helm, M.; Skorupa, W. [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Berencén, Y.; Ramírez, J. M.; Garrido, B. [Dept. Electrònica, Martí i Franquès 1, Universitat de Barcelona, 08028 Barcelona (Spain); Hiller, D. [IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)

    2014-09-28T23:59:59.000Z

    Rare earth doped metal-oxide-semiconductor (MOS) structures are of great interest for Si-based light emission. However, several physical limitations make it difficult to achieve the performance of light emitters based on compound semiconductors. To address this point, in this work the electroluminescence (EL) excitation and quenching mechanism of Er-implanted MOS structures with different designs of the dielectric stack are investigated. The devices usually consist of an injection layer made of SiO? and an Er-implanted layer made of SiO?, Si-rich SiO?, silicon nitride, or Si-rich silicon nitride. All structures implanted with Er show intense EL around 1540 nm with EL power efficiencies in the order of 2 × 10?³ (for SiO?:Er) or 2 × 10??(all other matrices) for lower current densities. The EL is excited by the impact of hot electrons with an excitation cross section in the range of 0.5–1.5 × 10?¹?cm?². Whereas the fraction of potentially excitable Er ions in SiO? can reach values up to 50%, five times lower values were observed for other matrices. The decrease of the EL decay time for devices with Si-rich SiO? or Si nitride compared to SiO? as host matrix implies an increase of the number of defects adding additional non-radiative de-excitation paths for Er³?. For all investigated devices, EL quenching cross sections in the 10?²? cm² range and charge-to-breakdown values in the range of 1–10 C cm?² were measured. For the present design with a SiO? acceleration layer, thickness reduction and the use of different host matrices did not improve the EL power efficiency or the operation lifetime, but strongly lowered the operation voltage needed to achieve intense EL.

  17. Influence of process parameters on properties of reactively sputtered tungsten nitride thin films

    SciTech Connect (OSTI)

    Addonizio, Maria L.; Castaldo, Anna; Antonaia, Alessandro; Gambale, Emilia; Iemmo, Laura [ENEA, Portici Research Centre, Piazzale E. Fermi 1, I-80055, Portici (Italy)

    2012-05-15T23:59:59.000Z

    Tungsten nitride (WN{sub x}) thin films were produced by reactive dc magnetron sputtering of tungsten in an Ar-N{sub 2} gas mixture. The influence of the deposition power on the properties of tungsten nitride has been analyzed and compared with that induced by nitrogen content variation in the sputtering gas. A combined analysis of structural, electrical and optical properties on thin WN{sub x} films obtained at different deposition conditions has been performed. It was found that at an N{sub 2} content of 14% a single phase structure of W{sub 2}N films was formed with the highest crystalline content. This sputtering gas composition was subsequently used for fabricating films at different deposition powers. Optical analysis showed that increasing the deposition power created tungsten nitride films with a more metallic character, which is confirmed with resistivity measurements. At low sputtering powers the resulting films were crystalline whereas, with an increase of power, an amorphous phase was also present. The incorporation of an excess of nitrogen atoms resulted in an expansion of the W{sub 2}N lattice and this effect was more pronounced at low deposition powers. Infrared analysis revealed that in WN{sub x} films deposited at low power, chemisorbed N{sub 2} molecules did not behave as ligands whereas at high deposition power they clearly appeared as ligands around metallic tungsten. In this study, the influence of the most meaningful deposition parameters on the phase transformation reaction path was established and deposition conditions suitable for producing thermally stable and highly crystalline W{sub 2}N films were found.

  18. Pulsed DC magnetron sputtered piezoelectric thin film aluminum nitride – Technology and piezoelectric properties

    SciTech Connect (OSTI)

    Stoeckel, C., E-mail: chris.stoeckel@zfm.tu-chemnitz.de; Kaufmann, C.; Hahn, R.; Schulze, R. [Center for Microtechnologies, Chemnitz University of Technology, Chemnitz 09126 (Germany); Billep, D. [Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz 09126 (Germany); Gessner, T. [Center for Microtechnologies, Chemnitz University of Technology, Chemnitz 09126 (Germany); Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz 09126 (Germany)

    2014-07-21T23:59:59.000Z

    Pulsed DC magnetron sputtered aluminum nitride (AlN) thin films are prepared on several seed layers and at different sputtering conditions. The piezoelectric c-axis (002) orientation of the AlN is analyzed with X-ray diffraction method. The transverse piezoelectric coefficient d{sub 31} is determined with a Laser-Doppler-Vibrometer at cantilevers and membranes by analytical calculations and finite element method. Additionally, thin film AlN on bulk silicon is used to characterize the longitudinal piezoelectric charge coefficient d{sub 33}.

  19. Rf-plasma synthesis of nanosize silicon carbide and nitride. Final report

    SciTech Connect (OSTI)

    Buss, R.J.

    1997-02-01T23:59:59.000Z

    A pulsed rf plasma technique is capable of generating ceramic particles of 10 manometer dimension. Experiments using silane/ammonia and trimethylchlorosilane/hydrogen gas mixtures show that both silicon nitride and silicon carbide powders can be synthesized with control of the average particle diameter from 7 to 200 nm. Large size dispersion and much agglomeration appear characteristic of the method, in contrast to results reported by another research group. The as produced powders have a high hydrogen content and are air and moisture sensitive. Post-plasma treatment in a controlled atmosphere at elevated temperature (800{degrees}C) eliminates the hydrogen and stabilizes the powder with respect to oxidation or hydrolysis.

  20. Control of interface fracture in silicon nitride ceramics: influence of different rare earth elements

    SciTech Connect (OSTI)

    Sun, E.Y.; Becher, P.F.; Waters, S.B.; Hsueh, Chun-Hway; Plucknett, K.P. [Oak Ridge National Lab., TN (United States); Hoffmann, M.J. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Keramik im Maschinenbau

    1996-10-01T23:59:59.000Z

    The toughness of self-reinforced silicon nitride ceramics is improved by enhancing crack deflection and crack bridging mechanisms. Both mechanisms rely on the interfacial debonding process between the elongated {Beta}-Si{sub 3}N{sub 4} grains and the intergranular amorphous phases. The various sintering additives used for densification may influence the interfacial debonding process by modifying the thermal and mechanical properties of the intergranular glasses, which will result in different residual thermal expansion mismatch stresses; and the atomic bonding structure across the {Beta}-Si{sub 3}N{sub 4} glass interface. Earlier studies indicated that self-reinforced silicon nitrides sintered with different rare earth additives and/or different Y{sub 2}O{sub 3}:AI{sub 2}0{sub 3} ratios could exhibit different fracture behavior that varied from intergranular to transgranular fracture. No studies have been conducted to investigate the influence of sintering additives on the interfacial fracture in silicon nitride ceramics. Because of the complexity of the material system and the extremely small scale, it is difficult to conduct quantitative analyses on the chemistry and stress states of the intergranular glass phases and to relate the results to the bulk properties. The influence of different sintering additives on the interfacial fracture behavior is assessed using model systems in which {Beta}-Si{sub 3}N{sub 4}whiskers are embedded in SIAIRE (RE: rare-earth) oxynitride glasses. By systematically varying the glass composition, the role of various rare-earth additives on interfacial fracture has been examined. Specifically, four different additives were investigated: Al{sub 2}0{sub 3}, Y{sub 2}0{sub 3}, La{sub 2}O{sub 3}, and Yb{sub 2}O{sub 3}. In addition, applying the results from the model systems, the R- curve behavior of self-reinforced silicon nitride ceramics sintered with different Y{sub 2}0{sub 3}:AI{sub 2}0{sub 3} ratios was characterized.

  1. Strength and fatigue of NT551 silicon nitride and NT551 diesel exhaust valves

    SciTech Connect (OSTI)

    Andrews, M.J.; Werezczak, A.A.; Kirkland, T.P.; Breder, K.

    2000-02-01T23:59:59.000Z

    The content of this report is excerpted from Mark Andrew's Ph.D. Thesis (Andrews, 1999), which was funded by a DOE/OTT High Temperature Materials Laboratory Graduate Fellowship. It involves the characterization of NT551 and valves fabricated with it. The motivations behind using silicon nitride (Si{sub 3}N{sub 4}) as an exhaust valve for a diesel engine are presented in this section. There are several economic factors that have encouraged the design and implementation of ceramic components for internal combustion (IC) engines. The reasons for selecting the diesel engine valve for this are also presented.

  2. Controlling Bandgap of Rippled Hexagonal Boron Nitride Membranes via Plasma Treatment

    SciTech Connect (OSTI)

    Zhang, H. X. [Institute for Functional Nanomaterials and Department of Physics, University of Puerto Rico; Feng, P. X. [Oak Ridge National Laboratory (ORNL)

    2011-01-01T23:59:59.000Z

    Few-layer rippled hexagonal boron nitride (h- BN) membranes were processed with hydrogen plasma, which exhibit distinct and pronounced changes in its electronic properties after the plasma treatment. The bandgaps of the h- BN membrane reduced from 5.6 eV at 0 s to 4.25 eV at 250s, which is a signature of transition from the insulating to the semiconductive regime. It typically required 250 s of plasma treatment to reach the saturation. It illustrates that twodimensional material with engineered electronic properties can be created by attaching other atoms or molecules.

  3. Sandia Energy - III-Nitride core-shell nanowire arrayed solar cells

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiationImplementing Nonlinear757 (1)Tara46EnergyPowerHighlights - EnergyIII-Nitride

  4. Electrical properties of dislocations in III-Nitrides

    SciTech Connect (OSTI)

    Cavalcoli, D.; Minj, A.; Pandey, S.; Cavallini, A. [Physics and Astronomy Dept. University of Bologna, Italy viale C Berti Pichat 6/II, Bologna (Italy)

    2014-02-21T23:59:59.000Z

    Research on GaN, AlN, InN (III-N) and their alloys is achieving new heights due their high potential applications in photonics and electronics. III-N semiconductors are mostly grown epitaxially on sapphire, and due to the large lattice mismatch and the differences in the thermal expansion coefficients, the structures usually contain many threading dislocations (TDs). While their structural properties have been widely investigated, their electrical characteristics and their role in the transport properties of the devices are still debated. In the present contribution we will show conductive AFM studies of TDs in GaN and Al/In GaN ternary alloys to evidence the role of strain, different surface polarity and composition on their electrical properties. Local I-V curves measured at TDs allowed us to clarify their role in the macroscopic electrical properties (leakage current, mobilities) of III-N based devices. Samples obtained by different growers (AIXTRON, III-V Lab) were studied. The comparison between the results obtained in the different alloys allowed us to understand the role of In and Al on the TDs electrical properties.

  5. Contact fatigue behavior and gas cell thermal wave NDE of sintered reaction bonded silicon nitride

    SciTech Connect (OSTI)

    Barla, J.R.; Edler, J.P.; Lin, H. [Eaton Corp. R & D, Southfield, MI (United States)] [and others

    1996-12-31T23:59:59.000Z

    Silicon nitride is being evaluated for potential applications as structural components subjected to contact fatigue loading. A new testing and evaluation methodology for evaluation of Hertzian contact fatigue damage in ceramic materials has been developed and is described. Contact fatigue damage is induced in three test specimens simultaneously. The material investigated is Eaton Corporation`s low cost E - Process Silicon Nitride. Tests were conducted at several Hertzian stress levels to evaluate contact fatigue damage behavior. Gas cell thermal wave NDE was employed to study the induced subsurface damage. Damage behavior was also investigated using optical microscopy. Two specimens were evaluated in detail; one that was tested for 17,400 cycles, P{sub max} = 2700 N and one that was tested for 1 x 10{sup 6} cycles, P{sub max} = 1800 N. The 2700 N specimen has a partial cone crack and contains a small concentration of vertical and shallow horizontal cracks. No evidence of a cone crack was detected on the 1800 N specimen. However, a larger concentration of horizontal microcracks at and just below the surface is present in this specimen, with particle debris in and around the surface contact area. Correlation of the optical microscopy observations with gas cell thermal wave NDE of the subsurface damage in these two specimens is discussed.

  6. Thickness limitations in carbon nanotube reinforced silicon nitride coatings synthesized by vapor infiltration

    SciTech Connect (OSTI)

    Eres, Gyula [ORNL

    2012-01-01T23:59:59.000Z

    Chemical vapor infiltration is a convenient method for synthesizing carbon nanotube (CNT)-reinforced ceramic coatings. The thickness over which infiltration is relatively uniform is limited by gas phase diffusion in the pore structure. These effects were investigated in two types of silicon nitride matrix composites. With CNTs that were distributed uniformly on the substrate surface dense coatings were limited to thicknesses of several microns. With dual structured CNT arrays produced by photolithography coatings up to 400 gm thick were obtained with minimal residual porosity. Gas transport into these dual structured materials was facilitated by creating micron sized channels between "CNT pillars" (i.e. each pillar consisted of a large number of individual CNTs). The experimental results are consistent with basic comparisons between the rates of gas diffusion and silicon nitride growth in porous structures. This analysis also provides a general insight into optimizing infiltration conditions during the fabrication of thick CNT-reinforced composite coatings. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  7. Energy transfer and 1.54 m emission in amorphous silicon nitride films S. O. Kucheyev,2

    E-Print Network [OSTI]

    spectrometry RBS and high-resolution transmission electron microscopy HRTEM to quantify the amount of Si, NEnergy transfer and 1.54 m emission in amorphous silicon nitride films S. Yerci,1 R. Li,1 S. O a broad energy spectrum and attributed to disorder-induced localized transitions in amorphous Er

  8. Power mixture and green body for producing silicon nitride base & articles of high fracture toughness and strength

    DOE Patents [OSTI]

    Huckabee, Marvin L. (Marlboro, MA); Buljan, Sergej-Tomislav (Acton, MA); Neil, Jeffrey T. (Acton, MA)

    1991-01-01T23:59:59.000Z

    A powder mixture and a green body for producing a silicon nitride-based article of improved fracture toughness and strength. The powder mixture includes 9a) a bimodal silicon nitride powder blend consisting essentially of about 10-30% by weight of a first silicon mitride powder of an average particle size of about 0.2 .mu.m and a surface area of about 8-12m.sup.2 g, and about 70-90% by weight of a second silicon nitride powder of an average particle size of about 0.4-0.6 .mu.m and a surface area of about 2-4 m.sup.2 /g, (b) about 10-50 percent by volume, based on the volume of the densified article, of refractory whiskers or fibers having an aspect ratio of about 3-150 and having an equivalent diameter selected to produce in the densified articel an equivalent diameter ratio of the whiskers or fibers to grains of silicon nitride of greater than 1.0, and (c) an effective amount of a suitable oxide densification aid. The green body is formed from the powder mixture, an effective amount of a suitable oxide densification aid, and an effective amount of a suitable organic binder.

  9. IDENTIFICATION Your Sample Box

    E-Print Network [OSTI]

    Liskiewicz, Maciej

    to Virginia Tech Soil Testing Lab, 145 Smyth Hall (MC 0465), 185 Ag Quad Ln, Blacksburg VA 24061, in sturdy, K, Ca, Mg, Zn, Mn, Cu, Fe, B, and soluble salts) NoCharge $16.00 Organic Matter $4.00 $6.00 Fax with soil sample and form; make check or money order payable to "Treasurer, Virginia Tech." COST PER SAMPLE

  10. Sampling system and method

    DOE Patents [OSTI]

    Decker, David L.; Lyles, Brad F.; Purcell, Richard G.; Hershey, Ronald Lee

    2013-04-16T23:59:59.000Z

    The present disclosure provides an apparatus and method for coupling conduit segments together. A first pump obtains a sample and transmits it through a first conduit to a reservoir accessible by a second pump. The second pump further conducts the sample from the reservoir through a second conduit.

  11. Rehabilitation Services Sample Occupations

    E-Print Network [OSTI]

    Ronquist, Fredrik

    /Industries Correction Agencies Drug Treatment Centers Addiction Counselor Advocacy Occupations Art Therapist BehavioralRehabilitation Services Sample Occupations Sample Work Settings Child & Day Care Centers Clinics................................ IIB 29-1000 E4 Careers in Counseling and Human Services .........IIB 21-1010 C7 Careers in Health Care

  12. Waste classification sampling plan

    SciTech Connect (OSTI)

    Landsman, S.D.

    1998-05-27T23:59:59.000Z

    The purpose of this sampling is to explain the method used to collect and analyze data necessary to verify and/or determine the radionuclide content of the B-Cell decontamination and decommissioning waste stream so that the correct waste classification for the waste stream can be made, and to collect samples for studies of decontamination methods that could be used to remove fixed contamination present on the waste. The scope of this plan is to establish the technical basis for collecting samples and compiling quantitative data on the radioactive constituents present in waste generated during deactivation activities in B-Cell. Sampling and radioisotopic analysis will be performed on the fixed layers of contamination present on structural material and internal surfaces of process piping and tanks. In addition, dose rate measurements on existing waste material will be performed to determine the fraction of dose rate attributable to both removable and fixed contamination. Samples will also be collected to support studies of decontamination methods that are effective in removing the fixed contamination present on the waste. Sampling performed under this plan will meet criteria established in BNF-2596, Data Quality Objectives for the B-Cell Waste Stream Classification Sampling, J. M. Barnett, May 1998.

  13. Theoretical study of the ammonia nitridation rate on an Fe (100) surface: A combined density functional theory and kinetic Monte Carlo study

    E-Print Network [OSTI]

    Yeo, Sang Chul

    Ammonia (NH[subscript 3]) nitridation on an Fe surface was studied by combining density functional theory (DFT) and kinetic Monte Carlo (kMC) calculations. A DFT calculation was performed to obtain the energy barriers ...

  14. Sample Changes and Issues

    Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

    EIA-914 Survey and HPDI. Figure 2 shows how this could change apparent production. The blue line shows the reported sample production as it would normally be reported under the...

  15. Water Sample Concentrator

    ScienceCinema (OSTI)

    Idaho National Laboratory

    2010-01-08T23:59:59.000Z

    Automated portable device that concentrates and packages a sample of suspected contaminated water for safe, efficient transport to a qualified analytical laboratory. This technology will help safeguard against pathogen contamination or chemical and biolog

  16. Dissolution actuated sample container

    DOE Patents [OSTI]

    Nance, Thomas A.; McCoy, Frank T.

    2013-03-26T23:59:59.000Z

    A sample collection vial and process of using a vial is provided. The sample collection vial has an opening secured by a dissolvable plug. When dissolved, liquids may enter into the interior of the collection vial passing along one or more edges of a dissolvable blocking member. As the blocking member is dissolved, a spring actuated closure is directed towards the opening of the vial which, when engaged, secures the vial contents against loss or contamination.

  17. SAMPLING AND ANALYSIS PROTOCOLS

    SciTech Connect (OSTI)

    Jannik, T; P Fledderman, P

    2007-02-09T23:59:59.000Z

    Radiological sampling and analyses are performed to collect data for a variety of specific reasons covering a wide range of projects. These activities include: Effluent monitoring; Environmental surveillance; Emergency response; Routine ambient monitoring; Background assessments; Nuclear license termination; Remediation; Deactivation and decommissioning (D&D); and Waste management. In this chapter, effluent monitoring and environmental surveillance programs at nuclear operating facilities and radiological sampling and analysis plans for remediation and D&D activities will be discussed.

  18. TANK 5 SAMPLING

    SciTech Connect (OSTI)

    Vrettos, N; William Cheng, W; Thomas Nance, T

    2007-11-26T23:59:59.000Z

    Tank 5 at the Savannah River Site has been used to store high level waste and is currently undergoing waste removal processes in preparation for tank closure. Samples were taken from two locations to determine the contents in support of Documented Safety Analysis (DSA) development for chemical cleaning. These samples were obtained through the use of the Drop Core Sampler and the Snowbank Sampler developed by the Engineered Equipment & Systems (EES) group of the Savannah River National Laboratory (SRNL).

  19. Liquid sampling system

    DOE Patents [OSTI]

    Larson, L.L.

    1984-09-17T23:59:59.000Z

    A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

  20. Liquid sampling system

    DOE Patents [OSTI]

    Larson, Loren L. (Idaho Falls, ID)

    1987-01-01T23:59:59.000Z

    A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed.

  1. CHARACTERIZATION OF MECHANICAL PERFORMANCE OF NT154 SILICON NITRIDE MICROTRUBINE ROTORS

    SciTech Connect (OSTI)

    Lin, Hua-Tay [ORNL; Ferber, Mattison K [ORNL; Waters, Shirley B [ORNL; Kirkland, Timothy Philip [ORNL

    2006-01-01T23:59:59.000Z

    This paper summarizes the results on recent component characterization efforts carried out to verify the mechanical reliability of NT154 silicon nitride microturbine rotors manufactured by Saint-Gobain. Mechanical properties of biaxial discs machined from airfoil as well as hub region of microturbine rotors were evaluated by a ball-on-ring test technique. Results showed that the mechanical properties of specimens from airfoils with as-processed surfaces exhibited lower characteristic strength than those machined from the hub region with as-machined surfaces. The differences in mechanical performance and reliability between as-processed components and simple-shaped test coupons appear to arise mainly from differences in strength limiting flaw type and microstructure verified by detailed electron microscopy analysis.

  2. Vertical coupling of laser glass microspheres to buried silicon nitride ellipses and waveguides

    E-Print Network [OSTI]

    Navarro-Urrios, Daniel; Capuj, Nestor E; Berencen, Yonder; Garrido, Blas; Tredicucci, Alessandro

    2015-01-01T23:59:59.000Z

    We demonstrate the integration of Nd3+ doped Barium-Titanium-Silicate microsphere lasers with a Silicon Nitride photonic platform. Devices with two different geometrical configurations for extracting the laser light to buried waveguides have been fabricated and characterized. The first configuration relies on a standard coupling scheme, where the microspheres are placed over strip waveguides. The second is based on a buried elliptical geometry whose working principle is that of an elliptical mirror. In the latter case, the input of a strip waveguide is placed on one focus of the ellipse, while a lasing microsphere is placed on top of the other focus. The fabricated elliptical geometry (ellipticity=0.9) presents a light collecting capacity that is 50% greater than that of the standard waveguide coupling configuration and could be further improved by increasing the ellipticity. Moreover, since the dimensions of the spheres are much smaller than those of the ellipses, surface planarization is not required. On th...

  3. Energy transfer and 1.54 {mu}m emission in amorphous silicon nitride films

    SciTech Connect (OSTI)

    Yerci, S.; Li, R. [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States); Kucheyev, S. O.; Buuren, T. van [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Basu, S. N. [Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States); Department of Mechanical Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215 (United States); Dal Negro, L. [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States); Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States)

    2009-07-20T23:59:59.000Z

    Er-doped amorphous silicon nitride films with various Si concentrations (Er:SiN{sub x}) were fabricated by reactive magnetron cosputtering followed by thermal annealing. The effects of Si concentrations and annealing temperatures were investigated in relation to Er emission and excitation processes. Efficient excitation of Er ions was demonstrated within a broad energy spectrum and attributed to disorder-induced localized transitions in amorphous Er:SiN{sub x}. A systematic optimization of the 1.54 {mu}m emission was performed and a fundamental trade-off was discovered between Er excitation and emission efficiency due to excess Si incorporation. These results provide an alternative approach for the engineering of sensitized Si-based light sources and lasers.

  4. Polarization doping and the efficiency of III-nitride optoelectronic devices

    SciTech Connect (OSTI)

    Kivisaari, Pyry; Oksanen, Jani; Tulkki, Jukka [Department of Biomedical Engineering and Computational Science, Aalto University, P.O. Box 12200, FI-00076 Aalto (Finland)] [Department of Biomedical Engineering and Computational Science, Aalto University, P.O. Box 12200, FI-00076 Aalto (Finland)

    2013-11-18T23:59:59.000Z

    The intrinsic polarization is generally considered a nuisance in III-nitride devices, but recent studies have shown that it can be used to enhance p- and n-type conductivity and even to replace impurity doping. We show by numerical simulations that polarization-doped light-emitting diode (LED) structures have a significant performance advantage over conventional impurity-doped LED structures. Our results indicate that polarization doping decreases electric fields inside the active region and potential barriers in the depletion region, as well as the magnitude of the quantum-confined Stark effect. The simulations also predict at least an order of magnitude increase in the current density corresponding to the maximum efficiency (i.e., smaller droop) as compared to impurity-doped structures. The obtained high doping concentrations could also enable, e.g., fabrication of III-N resonant tunneling diodes and improved ohmic contacts.

  5. SREELS analysis of oxygen-rich inversion domain boundaries in aluminum nitride

    SciTech Connect (OSTI)

    Bruley, J.; Zhao, J.C.; Notis, M.R. [Lehigh Univ. Bethlehem, PA (United States). Dept. of Materials Science and Engineering; Westwood, A.D. [IBM T.J. Watson Research Center, Yorktown Heights, NY (United States); Youngman, R.A. [Carborundum Co., Phoenix, AZ (United States)

    1995-09-01T23:59:59.000Z

    Spatially resolved electron energy loss spectroscopy analysis has been conducted on planar inversion domain boundaries in aluminum nitride. The defects were found to contain 1.5 monolayers of oxygen, in agreement with the most recent structural model of Westwood. From variations in near-edge structure, the local atomic environments of both oxygen and aluminum are compared with {alpha}-Al{sub 2}O{sub 3}, {gamma}-Al{sub 2}O{sub 3} and {gamma}-AlON standards. Based upon this study the structure of the inversion domain boundary is found to resemble that of the cubic {gamma}-AlON spinel, and eliminates from consideration those structural models based upon {alpha}-Al{sub 2}O{sub 3}. Furthermore, quantification of the shape resonances provided Al-O bond-length data from the inversion domain boundary interface. These distances closely agree with the Youngman Model that has recently been further refined by Westwood et al.

  6. Effects of hole localization on limiting p-type conductivity in oxide and nitride semiconductors

    SciTech Connect (OSTI)

    Lyons, J. L.; Janotti, A.; Van de Walle, C. G. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2014-01-07T23:59:59.000Z

    We examine how hole localization limits the effectiveness of substitutional acceptors in oxide and nitride semiconductors and explain why p-type doping of these materials has proven so difficult. Using hybrid density functional calculations, we find that anion-site substitutional impurities in AlN, GaN, InN, and ZnO lead to atomic-like states that localize on the impurity atom itself. Substitution with cation-site impurities, on the other hand, triggers the formation of polarons that become trapped on nearest-neighbor anions, generally leading to large ionization energies for these acceptors. Unlike shallow effective-mass acceptors, these two types of deep acceptors couple strongly with the lattice, significantly affecting the optical properties and severely limiting prospects for achieving p-type conductivity in these wide-band-gap materials.

  7. Steel bonded dense silicon nitride compositions and method for their fabrication

    DOE Patents [OSTI]

    Landingham, R.L.; Shell, T.E.

    1985-05-20T23:59:59.000Z

    A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500/sup 0/C in a vacuum with a refractory material and the stainless steel is then pressure bonded to the metallic coated surface by brazing it with nickel-copper-silver or nickel-copper-manganese alloys at a temperature in the range of about 850/sup 0/ to 950/sup 0/C in a vacuum. The two-stage bonding technique minimizes the temperature-expansion mismatch between the dissimilar materials.

  8. A cohesive law for interfaces in graphene/hexagonal boron nitride heterostructure

    SciTech Connect (OSTI)

    Zhang, Chenxi [Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, Florida 33146 (United States); Lou, Jun [Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77251 (United States); Song, Jizhou, E-mail: jzsong@gmail.com [Department of Engineering Mechanics and Soft Matter Research Center, Zhejiang University, Hangzhou 310027 (China)

    2014-04-14T23:59:59.000Z

    Graphene/hexagonal boron nitride (h-BN) heterostructure has showed great potential to improve the performance of graphene device. We have established the cohesive law for interfaces between graphene and monolayer or multi-layer h-BN based on the van der Waals force. The cohesive energy and cohesive strength are given in terms of area density of atoms on corresponding layers, number of layers, and parameters in the van der Waals force. It is found that the cohesive law in the graphene/multi-layer h-BN is dominated by the three h-BN layers which are closest to the graphene. The approximate solution is also obtained to simplify the expression of cohesive law. These results are very useful to study the deformation of graphene/h-BN heterostructure, which may have significant impacts on the performance and reliability of the graphene devices especially in the areas of emerging applications such as stretchable electronics.

  9. Thermal interface conductance across a graphene/hexagonal boron nitride heterojunction

    SciTech Connect (OSTI)

    Chen, Chun-Chung; Li, Zhen; Cronin, Stephen B. [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Shi, Li [Department of Mechanical Engineering and Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-02-24T23:59:59.000Z

    We measure thermal transport across a graphene/hexagonal boron nitride (h-BN) interface by electrically heating the graphene and measuring the temperature difference between the graphene and BN using Raman spectroscopy. Because the temperature of the graphene and BN are measured optically, this approach enables nanometer resolution in the cross-plane direction. A temperature drop of 60?K can be achieved across this junction at high electrical powers (14 mW). Based on the temperature difference and the applied power data, we determine the thermal interface conductance of this junction to be 7.4?×?10{sup 6}?Wm{sup ?2}K{sup ?1}, which is below the 10{sup 7}–10{sup 8}?Wm{sup ?2}K{sup ?1} values previously reported for graphene/SiO{sub 2} interface.

  10. Graphene on boron-nitride: Moiré pattern in the van der Waals energy

    SciTech Connect (OSTI)

    Neek-Amal, M. [Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Department of Physics, Shahid Rajaee University, Lavizan, Tehran 16788 (Iran, Islamic Republic of); Peeters, F. M. [Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2014-01-27T23:59:59.000Z

    The spatial dependence of the van der Waals (vdW) energy between graphene and hexagonal boron-nitride (h-BN) is investigated using atomistic simulations. The van der Waals energy between graphene and h-BN shows a hexagonal superlattice structure identical to the observed Moiré pattern in the local density of states, which depends on the lattice mismatch and misorientation angle between graphene and h-BN. Our results provide atomistic features of the weak van der Waals interaction between graphene and BN which are in agreement with experiment and provide an analytical expression for the size of the spatial variation of the weak van der Waals interaction. We also found that the A-B-lattice symmetry of graphene is broken along the armchair direction.

  11. Internal Oxidation-Nitridation of Ferritic Fe(Al) Alloys in Air

    SciTech Connect (OSTI)

    Pint, Bruce A [ORNL; Dwyer, Matthew J [Lehigh University, Bethlehem, PA; Deacon, Ryan M [Lehigh University, Bethlehem, PA

    2008-01-01T23:59:59.000Z

    Exposure of undoped Fe(Al) and Fe(Al)+Cr ferritic alloys in laboratory air at 900-1,000 C resulted in significant internal attack after 5,000 h, including oxides and underlying nitrides. In the most severely attacked alloys, kinetics based on mass gain and maximum penetration depth were linear; also, the deepest penetrations were a significant fraction of the specimen thickness, and were thickness-dependent. Little internal attack was observed at 700-800 C where these compositions may be used as coatings. The extent of internal attack did not decrease with increasing Al or Cr content which may indicate that rather than classical internal oxidation this attack is related to the permeation of N through a defective external scale. No internal attack was observed in alloys doped with Y, Zr, Hf or Ti where the substrate-alumina scale interface was flatter.

  12. III-nitride nanowires : novel materials for solid-state lighting.

    SciTech Connect (OSTI)

    Wang, George T.; Upadhya, Prashanth C. (Los Alamos National Laboratory, Los Alamos, NM); Prasankumar, Rohit P. (Los Alamos National Laboratory, Los Alamos, NM); Armstrong, Andrew M.; Huang, Jian Yu; Li, Qiming; Talin, Albert Alec (NIST, Gaithersburg, MD)

    2010-12-01T23:59:59.000Z

    Although planar heterostructures dominate current solid-state lighting architectures (SSL), 1D nanowires have distinct and advantageous properties that may eventually enable higher efficiency, longer wavelength, and cheaper devices. However, in order to fully realize the potential of nanowire-based SSL, several challenges exist in the areas of controlled nanowire synthesis, nanowire device integration, and understanding and controlling the nanowire electrical, optical, and thermal properties. Here recent results are reported regarding the aligned growth of GaN and III-nitride core-shell nanowires, along with extensive results providing insights into the nanowire properties obtained using cutting-edge structural, electrical, thermal, and optical nanocharacterization techniques. A new top-down fabrication method for fabricating periodic arrays of GaN nanorods and subsequent nanorod LED fabrication is also presented.

  13. Diffusion, convection, and solidification in cw-mode free electron laser nitrided titanium

    SciTech Connect (OSTI)

    Hoeche, Daniel; Mueller, Sven [II. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Shinn, Michelle [Free Electron Laser Group, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Schaaf, Peter [Institut fuer Werkstofftechnik, FG Werkstoffe der Elektrotechnik, TU Ilmenau, Postfach 10 05 65, 98684 Ilmenau (Germany)

    2009-04-15T23:59:59.000Z

    Titanium sheets were irradiated by free electron laser radiation in cw mode in pure nitrogen. Due to the interaction, nitrogen diffusion occurs and titanium nitride was synthesized in the tracks. Overlapping tracks have been utilized to create coatings in order to improve the tribological properties of the sheets. Caused by the local heating and the spatial dimension of the melt pool, convection effects were observed and related to the track properties. Stress, hardness, and nitrogen content were investigated with x-ray diffraction, nanoindention, and resonant nuclear reaction analysis. The measured results were correlated with the scan parameters, especially to the lateral track shift. Cross section micrographs were prepared and investigated by means of scanning electron microscopy. They show the solidification behavior, phase formation, and the nitrogen distribution. The experiments give an insight into the possibilities of materials processing using such a unique heat source.

  14. Dilute Group III-V nitride intermediate band solar cells with contact blocking layers

    DOE Patents [OSTI]

    Walukiewicz, Wladyslaw (Kensington, CA); Yu, Kin Man (Lafayette, CA)

    2012-07-31T23:59:59.000Z

    An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V.sub.OC) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

  15. Two-dimensional excitons in three-dimensional hexagonal boron nitride

    SciTech Connect (OSTI)

    Cao, X. K.; Lin, J. Y., E-mail: hx.jiang@ttu.edu; Jiang, H. X., E-mail: jingyu.lin@ttu.edu [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States); Clubine, B.; Edgar, J. H. [Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506 (United States)] [Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506 (United States)

    2013-11-04T23:59:59.000Z

    The recombination processes of excitons in hexagonal boron nitride (hBN) have been probed using time-resolved photoluminescence. It was found that the theory for two-dimensional (2D) exciton recombination describes well the exciton dynamics in three-dimensional hBN. The exciton Bohr radius and binding energy deduced from the temperature dependent exciton recombination lifetime is around 8?Å and 740?meV, respectively. The effective masses of electrons and holes in 2D hBN deduced from the generalized relativistic dispersion relation of 2D systems are 0.54m{sub o}, which are remarkably consistent with the exciton reduced mass deduced from the experimental data. Our results illustrate that hBN represents an ideal platform to study the 2D optical properties as well as the relativistic properties of particles in a condensed matter system.

  16. The structural distortion of the anti-perovskite nitride Ca sub 3 AsN

    SciTech Connect (OSTI)

    Chern, M.Y.; DiSalvo, F.J. (Cornell Univ., Ithaca, NY (United States)); Parise, J.B. (State Univ. of New York, Stony Brook, NY (United States)); Goldstone, J.A. (Los Alamos National lab., NM (United States))

    1992-02-01T23:59:59.000Z

    The structure of the distorted anti-perovskite nitride Ca{sub 3}AsN has been studied both by neutron powder diffraction at 305 and 15 K and by X-ray powder diffraction at room temperature. Ca{sub 3}AsN is distorted to an orthorhombic cell with a and b {approximately} {radical}2a{prime} and c{approximately}2a{prime}, where a{prime} is the lattice constant of the ideal undistorted cubic anti-perovskite. The distortion is produced by tilting of octahedra of Ca{sub 6}N and results in six short and six long bond distances of the twelvefold coordinated As atom by Ca atoms.

  17. Design and Testing of Kinetic Inductance Detectors Made of Titanium Nitride

    E-Print Network [OSTI]

    Diener, P; Yates, S J C; Lankwarden, Y J Y; Baselmans, J J A

    2013-01-01T23:59:59.000Z

    To use highly resistive material for Kinetic Inductance Detectors (KID), new designs have to be done, in part due to the impedance match needed between the KID chip and the whole 50 ohms readout circuit. Chips from two new hybrid designs, with an aluminum throughline coupled to titanium nitride microresonators, have been measured and compared to a TiN only chip. In the hybrid chips, parasitic temperature dependent box resonances are absent. The dark KID properties have been measured in a large set of resonators. A surprisingly long lifetime, up to 5.6 ms is observed in a few KIDs. For the other more reproducible devices, the mean electrical Noise Equivalent Power is 5.4 10-19 W.Hz1/2.

  18. Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia

    SciTech Connect (OSTI)

    Cloud, Andrew N.; Abelson, John R., E-mail: abelson@illinois.edu [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 W. Green St., Urbana, Illinois 61801 (United States); Davis, Luke M.; Girolami, Gregory S., E-mail: girolami@scs.illinois.edu [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801 (United States)

    2014-03-15T23:59:59.000Z

    Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300?°C from three recently synthesized M[N(t-Bu){sub 2}]{sub 2} precursors, where M?=?Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200?°C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18?nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities.

  19. PreparationSampleGuide:StartQuickISX Sample Preparation Guide

    E-Print Network [OSTI]

    straining the sample through a 70 micron nylon mesh strainer. If sample aggregation is a problem, we suggest

  20. The cost of silicon nitride powder: What must it be to compete?

    SciTech Connect (OSTI)

    Das, S.; Curlee, T.R.

    1992-02-01T23:59:59.000Z

    The ability of advanced ceramic components to compete with similar metallic parts will depend in part on current and future efforts to reduce the cost of ceramic parts. This paper examines the potential reductions in part cost that could result from the development of less expensive advanced ceramic powders. The analysis focuses specifically on two silicon nitride engine components -- roller followers and turbocharger rotors. The results of the process-cost models developed for this work suggest that reductions in the cost of advanced silicon nitride powder from its current level of about $20 per pound to about $5 per pound will not in itself be sufficient to lower the cost of ceramic parts below the current cost of similar metallic components. This work also examines if combinations of lower-cost powders and further improvements in other key technical parameters to which costs are most sensitive could push the cost of ceramics below the cost of metallics. Although these sensitivity analyses are reflective of technical improvements that are very optimistic, the resulting part costs are estimated to remain higher than similar metallic parts. Our findings call into question the widely-held notion that the cost of ceramic components must not exceed the cost of similar metallic parts if ceramics are to be competitive. Economic viability will ultimately be decided not on the basis of which part is less costly, but on an assessment of the marginal costs and benefits provided by ceramics and metallics. This analysis does not consider the benefits side of the equation. Our findings on the cost side of the equation suggest that the competitiveness of advanced ceramics will ultimately be decided by our ability to evaluate and communicate the higher benefits that advanced ceramic parts may offer.

  1. The cost of silicon nitride powder: What must it be to compete

    SciTech Connect (OSTI)

    Das, S.; Curlee, T.R.

    1992-02-01T23:59:59.000Z

    The ability of advanced ceramic components to compete with similar metallic parts will depend in part on current and future efforts to reduce the cost of ceramic parts. This paper examines the potential reductions in part cost that could result from the development of less expensive advanced ceramic powders. The analysis focuses specifically on two silicon nitride engine components -- roller followers and turbocharger rotors. The results of the process-cost models developed for this work suggest that reductions in the cost of advanced silicon nitride powder from its current level of about $20 per pound to about $5 per pound will not in itself be sufficient to lower the cost of ceramic parts below the current cost of similar metallic components. This work also examines if combinations of lower-cost powders and further improvements in other key technical parameters to which costs are most sensitive could push the cost of ceramics below the cost of metallics. Although these sensitivity analyses are reflective of technical improvements that are very optimistic, the resulting part costs are estimated to remain higher than similar metallic parts. Our findings call into question the widely-held notion that the cost of ceramic components must not exceed the cost of similar metallic parts if ceramics are to be competitive. Economic viability will ultimately be decided not on the basis of which part is less costly, but on an assessment of the marginal costs and benefits provided by ceramics and metallics. This analysis does not consider the benefits side of the equation. Our findings on the cost side of the equation suggest that the competitiveness of advanced ceramics will ultimately be decided by our ability to evaluate and communicate the higher benefits that advanced ceramic parts may offer.

  2. Crystal and Electronic Structures of Neptunium Nitrides Synthesized Using a Fluoride Route

    SciTech Connect (OSTI)

    Silva, G W Chinthaka M [ORNL; Weck, Dr. Phil F. [Sandia National Laboratories (SNL); Eunja, Dr. Kim [University of Nevada, Las Vegas; Yeamans, Dr. Charles B. [Lawrence Livermore National Laboratory (LLNL); Cerefice, Gary S. [University of Nevada, Las Vegas; Sattelberger, Alfred P [Argonne National Laboratory (ANL); Czerwinski, Ken R. [University of Nevada, Las Vegas

    2012-01-01T23:59:59.000Z

    A low-temperature fluoride route was utilized to synthesize neptunium mononitride, NpN. Through the development of this process, two new neptunium nitride species, NpN{sub 2} and Np{sub 2}N{sub 3}, were identified. The NpN{sub 2} and Np{sub 2}N{sub 3} have crystal structures isomorphous to those of UN{sub 2} and U{sub 2}N{sub 3}, respectively. NpN{sub 2} crystallizes in a face-centered cubic CaF{sub 2}-type structure with a space group of Fm3m and a refined lattice parameter of 5.3236(1) {angstrom}. The Np{sub 2}N{sub 3} adopts the body-centered cubic Mn{sub 2}O{sub 3}-type structure with a space group of Ia{bar 3}. Its refined lattice parameter is 10.6513(4) {angstrom}. The NpN synthesis at temperatures {le} 900 C using the fluoride route discussed here was also demonstrated. Previous computational studies of the neptunium nitride system have focused exclusively on the NpN phase because no evidence was reported experimentally on the presence of NpN{sub x} systems. Here, the crystal structures of NpN{sub 2} and Np{sub 2}N{sub 3} are discussed for the first time, confirming the experimental results by density functional calculations (DFT). These DFT calculations were performed within the local-density approximation (LDA+U) and the generalized-gradient approximation (GGA+U) corrected with an effective Hubbard parameter to account for the strong on-site Coulomb repulsion between Np 5f electrons. The effects of the spin-orbit coupling in the GGA+U calculations have also been investigated for NpN{sub 2} and NpN.

  3. DISORDERING OF InGaN/GaN SUPERLATTICES AFTER HIGH-PRESSURE M.D. McCluskey*, L.T. Romano**, B.S. Krusor**, D. Hofstetter**, D.P. Bour**, M. Kneissl**,

    E-Print Network [OSTI]

    McCluskey, Matthew

    DISORDERING OF InGaN/GaN SUPERLATTICES AFTER HIGH-PRESSURE ANNEALING M.D. McCluskey*, L.T. Romano Internet J. Nitride Semicond. Res. 4S1, G3.42 (1999) ABSTRACT Interdiffusion of In and Ga is observed in InGaN of up to 15 kbar were applied during the annealing treatments to prevent decomposition of the InGaN

  4. Fluid sampling system

    DOE Patents [OSTI]

    Houck, E.D.

    1994-10-11T23:59:59.000Z

    An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to be decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank. 4 figs.

  5. Fluid sampling system

    DOE Patents [OSTI]

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01T23:59:59.000Z

    An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank.

  6. Viscous sludge sample collector

    DOE Patents [OSTI]

    Beitel, George A [Richland, WA

    1983-01-01T23:59:59.000Z

    A vertical core sample collection system for viscous sludge. A sample tube's upper end has a flange and is attached to a piston. The tube and piston are located in the upper end of a bore in a housing. The bore's lower end leads outside the housing and has an inwardly extending rim. Compressed gas, from a storage cylinder, is quickly introduced into the bore's upper end to rapidly accelerate the piston and tube down the bore. The lower end of the tube has a high sludge entering velocity to obtain a full-length sludge sample without disturbing strata detail. The tube's downward motion is stopped when its upper end flange impacts against the bore's lower end inwardly extending rim.

  7. Experimental Scattershot Boson Sampling

    E-Print Network [OSTI]

    Marco Bentivegna; Nicolò Spagnolo; Chiara Vitelli; Fulvio Flamini; Niko Viggianiello; Ludovico Latmiral; Paolo Mataloni; Daniel J. Brod; Ernesto F. Galvão; Andrea Crespi; Roberta Ramponi; Roberto Osellame; Fabio Sciarrino

    2015-05-14T23:59:59.000Z

    Boson Sampling is a computational task strongly believed to be hard for classical computers, but efficiently solvable by orchestrated bosonic interference in a specialised quantum computer. Current experimental schemes, however, are still insufficient for a convincing demonstration of the advantage of quantum over classical computation. A new variation of this task, Scattershot Boson Sampling, leads to an exponential increase in speed of the quantum device, using a larger number of photon sources based on parametric downconversion. This is achieved by having multiple heralded single photons being sent, shot by shot, into different random input ports of the interferometer. Here we report the first Scattershot Boson Sampling experiments, where six different photon-pair sources are coupled to integrated photonic circuits. We employ recently proposed statistical tools to analyse our experimental data, providing strong evidence that our photonic quantum simulator works as expected. This approach represents an important leap toward a convincing experimental demonstration of the quantum computational supremacy.

  8. Final LDRD report : the physics of 1D and 2D electron gases in III-nitride heterostructure NWs.

    SciTech Connect (OSTI)

    Armstrong, Andrew M.; Arslan, Ilke (Sandia National Laboratories, Livermore, CA); Upadhya, Prashanth C. (Los Alamos National Laboratory, Los Alamos, NM); Morales, Eugenia T. (Sandia National Laboratories, Livermore, CA); Leonard, Francois Leonard (Sandia National Laboratories, Livermore, CA); Li, Qiming; Wang, George T.; Talin, Albert Alec (Sandia National Laboratories, Livermore, CA); Prasankumar, Rohit P. (Los Alamos National Laboratory, Los Alamos, NM); Lin, Yong

    2009-09-01T23:59:59.000Z

    The proposed work seeks to demonstrate and understand new phenomena in novel, freestanding III-nitride core-shell nanowires, including 1D and 2D electron gas formation and properties, and to investigate the role of surfaces and heterointerfaces on the transport and optical properties of nanowires, using a combined experimental and theoretical approach. Obtaining an understanding of these phenomena will be a critical step that will allow development of novel, ultrafast and ultraefficient nanowire-based electronic and photonic devices.

  9. Environmental Science: Sample Pathway

    E-Print Network [OSTI]

    Goldberg, Bennett

    Environmental Science: Sample Pathway Semester I Semester II Freshman Year CGS Core CGS Core GE 100 & 124) MA 115 Statistics Summer Environmental Internship Junior Year CH 171 Chem for Health Sciences CH in Environmental Sciences is 17 courses. Courses taken to satisfy CAS major requirements (required, principal, core

  10. Application of Self-Propagating High Temperature Synthesis to the Fabrication of Actinide Bearing Nitride and Other Ceramic Nuclear Fuels

    SciTech Connect (OSTI)

    John J. Moore, Douglas E. Burkes, Collin D. Donohoue, Marissa M. Reigel, J. Rory Kennedy

    2009-05-18T23:59:59.000Z

    The high vapor pressures of americium (Am) and americium nitride (AmN) are cause for concern in producing nitride ceramic nuclear fuel that contains Am. Along with the problem of Am retention during the sintering phases of current processing methods, are additional concerns of producing a consistent product of desirable homogeneity, density and porosity. Similar difficulties have been experienced during the laboratory scale process development stage of producing metal alloys containing Am wherein compact powder sintering methods had to be abandoned. Therefore, there is an urgent need to develop a low-temperature or low–heat fuel fabrication process for the synthesis of Am-containing ceramic fuels. Self-propagating high temperature synthesis (SHS), also called combustion synthesis, offers such an alternative process for the synthesis of Am nitride fuels. Although SHS takes thermodynamic advantage of the high combustion temperatures of these exothermic SHS reactions to synthesize the required compounds, the very fast heating, reaction and cooling rates can kinetically generate extremely fast reaction rates and facilitate the retention of volatile species within the rapidly propagating SHS reaction front. The initial objective of the research program is to use Mn as the surrogate for Am to synthesize a reproducible, dense, high quality Zr-Mn-N ceramic compound. Having determined the fundamental SHS reaction parameters and optimized SHS processing steps using Mn as the surrogate for Am, the technology will be transferred to Idaho National Laboratory to successfully synthesize a high quality Zr-Am-N ceramic fuel.

  11. Pre-Oxidized and Nitrided Stainless Steel Foil for Proton Exchange Membrane Fuel Cell Bipolar Plates: Part 2- Single-Cell Fuel Cell Evaluation of Stamped Plates

    SciTech Connect (OSTI)

    Toops, Todd J [ORNL; Brady, Michael P [ORNL; Tortorelli, Peter F [ORNL; Pihl, Josh A [ORNL; EstevezGenCell, Francisco [GenCell Corp; Connors, Dan [GenCell Corp; Garzon, Fernando [Los Alamos National Laboratory (LANL); Rockward, Tommy [Los Alamos National Laboratory (LANL); Gervasio, Don [Arizona State University; Kosaraju, S.H. [Arizona State University

    2010-01-01T23:59:59.000Z

    Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr{sub 2}N, CrN, TiN, V{sub 2}N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of proton exchange membrane (PEM) single-cell fuel cell studies of stamped and pre-oxidized/nitrided developmental Fe-20Cr-4V weight percent (wt.%) and commercial type 2205 stainless steel alloy foils. The single-cell fuel cell behavior of the stamped and pre-oxidized/nitrided material was compared to as-stamped (no surface treatment) 904L, 2205, and Fe-20Cr-4V stainless steel alloy foils and machined graphite of similar flow field design. The best fuel cell behavior among the alloys was exhibited by the pre-oxidized/nitrided Fe-20Cr-4V, which exhibited {approx}5-20% better peak power output than untreated Fe-20Cr-4V, 2205, and 904L metal stampings. Durability was assessed for pre-oxidized/nitrided Fe-20Cr-4V, 904L metal, and graphite plates by 1000+ h of cyclic single-cell fuel cell testing. All three materials showed good durability with no significant degradation in cell power output. Post-test analysis indicated no metal ion contamination of the membrane electrode assemblies (MEAs) occurred with the pre-oxidized and nitrided Fe-20Cr-4V or graphite plates, and only a minor amount of contamination with the 904L plates.

  12. Nanostructural engineering of nitride nucleation layers for GaN substrate dislocation reduction.

    SciTech Connect (OSTI)

    Koleske, Daniel David; Lee, Stephen Roger; Lemp, Thomas Kerr; Coltrin, Michael Elliott; Cross, Karen Charlene; Thaler, Gerald

    2009-07-01T23:59:59.000Z

    With no lattice matched substrate available, sapphire continues as the substrate of choice for GaN growth, because of its reasonable cost and the extensive prior experience using it as a substrate for GaN. Surprisingly, the high dislocation density does not appear to limit UV and blue LED light intensity. However, dislocations may limit green LED light intensity and LED lifetime, especially as LEDs are pushed to higher current density for high end solid state lighting sources. To improve the performance for these higher current density LEDs, simple growth-enabled reductions in dislocation density would be highly prized. GaN nucleation layers (NLs) are not commonly thought of as an application of nano-structural engineering; yet, these layers evolve during the growth process to produce self-assembled, nanometer-scale structures. Continued growth on these nuclei ultimately leads to a fully coalesced film, and we show in this research program that their initial density is correlated to the GaN dislocation density. In this 18 month program, we developed MOCVD growth methods to reduce GaN dislocation densities on sapphire from 5 x 10{sup 8} cm{sup -2} using our standard delay recovery growth technique to 1 x 10{sup 8} cm{sup -2} using an ultra-low nucleation density technique. For this research, we firmly established a correlation between the GaN nucleation thickness, the resulting nucleation density after annealing, and dislocation density of full GaN films grown on these nucleation layers. We developed methods to reduce the nuclei density while still maintaining the ability to fully coalesce the GaN films. Ways were sought to improve the GaN nuclei orientation by improving the sapphire surface smoothness by annealing prior to the NL growth. Methods to eliminate the formation of additional nuclei once the majority of GaN nuclei were developed using a silicon nitride treatment prior to the deposition of the nucleation layer. Nucleation layer thickness was determined using optical reflectance and the nucleation density was determined using atomic force microscopy (AFM) and Nomarski microscopy. Dislocation density was measured using X-ray diffraction and AFM after coating the surface with silicon nitride to delineate all dislocation types. The program milestone of producing GaN films with dislocation densities of 1 x 10{sup 8} cm{sup -2} was met by silicon nitride treatment of annealed sapphire followed by the multiple deposition of a low density of GaN nuclei followed by high temperature GaN growth. Details of this growth process and the underlying science are presented in this final report along with problems encountered in this research and recommendations for future work.

  13. Characterization of sampling cyclones

    E-Print Network [OSTI]

    Moore, Murray Edward

    1986-01-01T23:59:59.000Z

    Farland, who' provided an excellent opportunity for the enhancement of my engineering career. To Dr. Best for his patient snd competent assistance in this project. To Dr. Parish who gave his service to my graduate committee. To Bob DeOtte and Carlos Ortiz... in air sampling standards, several different samplers have been developed which utilize either inertial impaction or cyclonic flow fractionation techniques. For example, a 10 pm cutpoint size selective inlet was developed by McFarland, Ortiz...

  14. Post-Award Deliverables Sample (Second Part of Sample Deliverables...

    Broader source: Energy.gov (indexed) [DOE]

    samplereptgrqmts.doc More Documents & Publications ESPC Sample Deliverables for Task Orders (IDIQ Attachment. J-4) Sample Statement of Work - Standard Service Offerings for...

  15. Decoupled Sampling for Graphics Pipelines

    E-Print Network [OSTI]

    Ragan-Kelley, Jonathan Millar

    We propose a generalized approach to decoupling shading from visibility sampling in graphics pipelines, which we call decoupled sampling. Decoupled sampling enables stochastic supersampling of motion and defocus blur at ...

  16. Fluid sampling apparatus and method

    DOE Patents [OSTI]

    Yeamans, David R. (Los Alamos, NM)

    1998-01-01T23:59:59.000Z

    Incorporation of a bellows in a sampling syringe eliminates ingress of contaminants, permits replication of amounts and compression of multiple sample injections, and enables remote sampling for off-site analysis.

  17. Fluid sampling apparatus and method

    DOE Patents [OSTI]

    Yeamans, D.R.

    1998-02-03T23:59:59.000Z

    Incorporation of a bellows in a sampling syringe eliminates ingress of contaminants, permits replication of amounts and compression of multiple sample injections, and enables remote sampling for off-site analysis. 3 figs.

  18. Soil sampling kit and a method of sampling therewith

    DOE Patents [OSTI]

    Thompson, Cyril V. (Knoxville, TN)

    1991-01-01T23:59:59.000Z

    A soil sampling device and a sample containment device for containing a soil sample is disclosed. In addition, a method for taking a soil sample using the soil sampling device and soil sample containment device to minimize the loss of any volatile organic compounds contained in the soil sample prior to analysis is disclosed. The soil sampling device comprises two close fitting, longitudinal tubular members of suitable length, the inner tube having the outward end closed. With the inner closed tube withdrawn a selected distance, the outer tube can be inserted into the ground or other similar soft material to withdraw a sample of material for examination. The inner closed end tube controls the volume of the sample taken and also serves to eject the sample. The soil sample containment device has a sealing member which is adapted to attach to an analytical apparatus which analyzes the volatile organic compounds contained in the sample. The soil sampling device in combination with the soil sample containment device allow an operator to obtain a soil sample containing volatile organic compounds and minimizing the loss of the volatile organic compounds prior to analysis of the soil sample for the volatile organic compounds.

  19. Soil sampling kit and a method of sampling therewith

    DOE Patents [OSTI]

    Thompson, C.V.

    1991-02-05T23:59:59.000Z

    A soil sampling device and a sample containment device for containing a soil sample is disclosed. In addition, a method for taking a soil sample using the soil sampling device and soil sample containment device to minimize the loss of any volatile organic compounds contained in the soil sample prior to analysis is disclosed. The soil sampling device comprises two close fitting, longitudinal tubular members of suitable length, the inner tube having the outward end closed. With the inner closed tube withdrawn a selected distance, the outer tube can be inserted into the ground or other similar soft material to withdraw a sample of material for examination. The inner closed end tube controls the volume of the sample taken and also serves to eject the sample. The soil sample containment device has a sealing member which is adapted to attach to an analytical apparatus which analyzes the volatile organic compounds contained in the sample. The soil sampling device in combination with the soil sample containment device allows an operator to obtain a soil sample containing volatile organic compounds and minimizing the loss of the volatile organic compounds prior to analysis of the soil sample for the volatile organic compounds. 11 figures.

  20. Methods for and products of processing nanostructure nitride, carbonitride and oxycarbonitride electrode power materials by utilizing sol gel technology for supercapacitor applications

    DOE Patents [OSTI]

    Huang, Yuhong (West Hills, CA); Wei, Oiang (West Hills, CA); Chu, Chung-tse (Chatsworth, CA); Zheng, Haixing (Oak Park, CA)

    2001-01-01T23:59:59.000Z

    Metal nitride, carbonitride, and oxycarbonitride powder with high surface area (up to 150 m.sup.2 /g) is prepared by using sol-gel process. The metal organic precursor, alkoxides or amides, is synthesized firstly. The metal organic precursor is modified by using unhydrolyzable organic ligands or templates. A wet gel is formed then by hydrolysis and condensation process. The solvent in the wet gel is then be removed supercritically to form porous amorphous hydroxide. This porous hydroxide materials is sintered to 725.degree. C. under the ammonia flow and porous nitride powder is formed. The other way to obtain high surface area nitride, carbonitride, and oxycarbonitride powder is to pyrolyze polymerized templated metal amides aerogel in an inert atmosphere. The electrochemical capacitors are prepared by using sol-gel prepared nitride, carbonitride, and oxycarbonitride powder. Two methods are used to assemble the capacitors. Electrode is formed either by pressing the mixture of nitride powder and binder to a foil, or by depositing electrode coating onto metal current collector. The binder or coating is converted into a continuous network of electrode material after thermal treatment to provide enhanced energy and power density. Liquid electrolyte is soaked into porous electrode. The electrochemical capacitor assembly further has a porous separator layer between two electrodes/electrolyte and forming a unit cell.

  1. Improved growth of GaN layers on ultra thin silicon nitride/Si (1 1 1) by RF-MBE

    SciTech Connect (OSTI)

    Kumar, Mahesh; Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India) [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Bhat, Thirumaleshwara N.; Rajpalke, Mohana K. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)] [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Misra, P.; Kukreja, L.M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)] [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Sinha, Neeraj [Office of Principal Scientific Advisor, Government of India, New Delhi 110011 (India)] [Office of Principal Scientific Advisor, Government of India, New Delhi 110011 (India); Kalghatgi, A.T. [Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India)] [Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)

    2010-11-15T23:59:59.000Z

    High-quality GaN epilayers were grown on Si (1 1 1) substrates by molecular beam epitaxy using a new growth process sequence which involved a substrate nitridation at low temperatures, annealing at high temperatures, followed by nitridation at high temperatures, deposition of a low-temperature buffer layer, and a high-temperature overgrowth. The material quality of the GaN films was also investigated as a function of nitridation time and temperature. Crystallinity and surface roughness of GaN was found to improve when the Si substrate was treated under the new growth process sequence. Micro-Raman and photoluminescence (PL) measurement results indicate that the GaN film grown by the new process sequence has less tensile stress and optically good. The surface and interface structures of an ultra thin silicon nitride film grown on the Si surface are investigated by core-level photoelectron spectroscopy and it clearly indicates that the quality of silicon nitride notably affects the properties of GaN growth.

  2. Synthesis of nanostructured materials in supercritical ammonia: nitrides, metals and oxides Desmoulins-Krawiec S., Aymonier C., Loppinet-Serani A., Weill F., Grosse S., Etourneau J., Cansell F.

    E-Print Network [OSTI]

    Boyer, Edmond

    N in supercritical cryogenic nitrogen by self-propagating-high- temperature synthesis (6.21 MPa, ­141 °C);19 (ii) GaSynthesis of nanostructured materials in supercritical ammonia: nitrides, metals and oxides. Abstract : In this study, the synthesis of nanostructured particles of nitrides (Cr2N, Co2N, Fe4N, Cu3N, Ni

  3. NID Copper Sample Analysis

    SciTech Connect (OSTI)

    Kouzes, Richard T.; Zhu, Zihua

    2011-09-12T23:59:59.000Z

    The current focal point of the nuclear physics program at PNNL is the MAJORANA DEMONSTRATOR, and the follow-on Tonne-Scale experiment, a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0???). This experiment requires the use of germanium isotopically enriched in 76Ge. The MAJORANA DEMONSTRATOR is a DOE and NSF funded project with a major science impact. The DEMONSTRATOR will utilize 76Ge from Russia, but for the Tonne-Scale experiment it is hoped that an alternate technology, possibly one under development at Nonlinear Ion Dynamics (NID), will be a viable, US-based, lower-cost source of separated material. Samples of separated material from NID require analysis to determine the isotopic distribution and impurities. DOE is funding NID through an SBIR grant for development of their separation technology for application to the Tonne-Scale experiment. The Environmental Molecular Sciences facility (EMSL), a DOE user facility at PNNL, has the required mass spectroscopy instruments for making isotopic measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR and for the development of the future separation technology required for the Tonne-Scale experiment. A sample of isotopically separated copper was provided by NID to PNNL in January 2011 for isotopic analysis as a test of the NID technology. The results of that analysis are reported here. A second sample of isotopically separated copper was provided by NID to PNNL in August 2011 for isotopic analysis as a test of the NID technology. The results of that analysis are also reported here.

  4. Germanium-76 Sample Analysis

    SciTech Connect (OSTI)

    Kouzes, Richard T.; Engelhard, Mark H.; Zhu, Zihua

    2011-04-01T23:59:59.000Z

    The MAJORANA DEMONSTRATOR is a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0???). The DEMONSTRATOR will utilize 76Ge from Russia, and the first one gram sample was received from the supplier for analysis on April 24, 2011. The Environmental Molecular Sciences facility, a DOE user facility at PNNL, was used to make the required isotopic and chemical purity measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR. The results of this first analysis are reported here.

  5. Stack sampling apparatus

    DOE Patents [OSTI]

    Lind, Randall F; Lloyd, Peter D; Love, Lonnie J; Noakes, Mark W; Pin, Francois G; Richardson, Bradley S; Rowe, John C

    2014-09-16T23:59:59.000Z

    An apparatus for obtaining samples from a structure includes a support member, at least one stabilizing member, and at least one moveable member. The stabilizing member has a first portion coupled to the support member and a second portion configured to engage with the structure to restrict relative movement between the support member and the structure. The stabilizing member is radially expandable from a first configuration where the second portion does not engage with a surface of the structure to a second configuration where the second portion engages with the surface of the structure.

  6. Draft Sample Collection Instrument

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny:Revised Finding of No53197E T ADRAFTJanuaryDominionDowDepartmentPublic5 5Sample

  7. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 AugustAFRICAN3u ;;;::Sampling at the Sherwood,

  8. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTuba City, Arizona, DisposalFourthN V O 1CentralGroundwater,Sampling at the

  9. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTuba City, Arizona, DisposalFourthN V O 1CentralGroundwater,Sampling at the4

  10. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTuba City, Arizona, DisposalFourthN V O 1CentralGroundwater,Sampling at

  11. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTuba City, Arizona, DisposalFourthN V O 1CentralGroundwater,Sampling

  12. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTuba City, Arizona, DisposalFourthN V O 1CentralGroundwater,SamplingTuba

  13. September 2004 Water Sampling

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTuba City, Arizona, DisposalFourthN V O 1CentralGroundwater,SamplingTubaand

  14. Defect induced plasticity and failure mechanism of boron nitride nanotubes under tension

    SciTech Connect (OSTI)

    Anoop Krishnan, N. M., E-mail: anoopnm@civil.iisc.ernet.in; Ghosh, Debraj [Indian Institute of Science, Bangalore 560012 (India)

    2014-07-28T23:59:59.000Z

    The effects of Stone-Wales (SW) and vacancy defects on the failure behavior of boron nitride nanotubes (BNNTs) under tension are investigated using molecular dynamics simulations. The Tersoff-Brenner potential is used to model the atomic interaction and the temperature is maintained close to 300?K. The effect of a SW defect is studied by determining the failure strength and failure mechanism of nanotubes with different radii. In the case of a vacancy defect, the effect of an N-vacancy and a B-vacancy is studied separately. Nanotubes with different chiralities but similar diameter is considered first to evaluate the chirality dependence. The variation of failure strength with the radius is then studied by considering nanotubes of different diameters but same chirality. It is observed that the armchair BNNTs are extremely sensitive to defects, whereas the zigzag configurations are the least sensitive. In the case of pristine BNNTs, both armchair and zigzag nanotubes undergo brittle failure, whereas in the case of defective BNNTs, only the zigzag ones undergo brittle failure. An interesting defect induced plastic behavior is observed in defective armchair BNNTs. For this nanotube, the presence of a defect triggers mechanical relaxation by bond breaking along the closest zigzag helical path, with the defect as the nucleus. This mechanism results in a plastic failure.

  15. Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

    DOE Patents [OSTI]

    McCallum, R. William (Ames, IA); Branagan, Daniel J. (Ames, IA)

    1996-01-23T23:59:59.000Z

    A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.

  16. High-Responsivity Graphene-Boron Nitride Photodetector and Autocorrelator in a Silicon Photonic Integrated Circuit

    E-Print Network [OSTI]

    Shiue, Ren-Jye; Wang, Yifei; Peng, Cheng; Robertson, Alexander D; Efetov, Dimitri; Assefa, Solomon; Koppens, Frank H L; Hone, James; Englund, Dirk

    2015-01-01T23:59:59.000Z

    Graphene and other two-dimensional (2D) materials have emerged as promising materials for broadband and ultrafast photodetection and optical modulation. These optoelectronic capabilities can augment complementary metal-oxide-semiconductor (CMOS) devices for high-speed and low-power optical interconnects. Here, we demonstrate an on-chip ultrafast photodetector based on a two-dimensional heterostructure consisting of high-quality graphene encapsulated in hexagonal boron nitride. Coupled to the optical mode of a silicon waveguide, this 2D heterostructure-based photodetector exhibits a maximum responsivity of 0.36 A/W and high-speed operation with a 3 dB cut-off at 42 GHz. From photocurrent measurements as a function of the top-gate and source-drain voltages, we conclude that the photoresponse is consistent with hot electron mediated effects. At moderate peak powers above 50 mW, we observe a saturating photocurrent consistent with the mechanisms of electron-phonon supercollision cooling. This nonlinear photorespo...

  17. Strong, Tough Ceramics Containing Microscopic Reinforcements: Tailoring In-Situ Reinforced Silicon Nitride Ceramics

    SciTech Connect (OSTI)

    Becher, P.F.

    1999-06-27T23:59:59.000Z

    Ceramics with their hardness, chemical stability, and refractoriness could be used to design more efficient energy generation and conversion systems as well as numerous other applications. However, we have needed to develop a fundamental understanding of how to tailor ceramics to improve their performance, especially to overcome their brittle nature. One of the advances in this respect was the incorporation of very strong microscopic rod-like reinforcements in the form of whiskers that serve to hold the ceramic together making it tougher and resistant to fracture. This microscopic reinforcement approach has a number of features that are similar to continuous fiber-reinforced ceramics; however, some of the details are modified. For instance, the strengths of the microscopic reinforcements must be higher as they typically have much stronger interfaces. For instance, single crystal silicon carbide whiskers can have tensile strengths in excess of {ge}7 GPa or >2 times that of continuous fibers. Furthermore, reinforcement pullout is limited to lengths of a few microns in the case of microscopic reinforcement due as much to the higher interfacial shear resistance as to the limit of the reinforcement lengths. On the other hand, the microscopic reinforcement approach can be generated in-situ during the processing of ceramics. A remarkable example of this is found in silicon nitride ceramics where elongated rod-like shape grains can be formed when the ceramic is fired at elevated temperatures to form a dense component.

  18. Influence of scandium concentration on power generation figure of merit of scandium aluminum nitride thin films

    SciTech Connect (OSTI)

    Akiyama, Morito; Nagase, Toshimi [Measurement Solution Research Center, National Institute of Advanced Industrials Science and Technology, Tosu, Saga 841-0052 (Japan)] [Measurement Solution Research Center, National Institute of Advanced Industrials Science and Technology, Tosu, Saga 841-0052 (Japan); Umeda, Keiichi; Honda, Atsushi [Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto 617-8555 (Japan)] [Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto 617-8555 (Japan)

    2013-01-14T23:59:59.000Z

    The authors have investigated the influence of scandium concentration on the power generation figure of merit (FOM) of scandium aluminum nitride (Sc{sub x}Al{sub 1-x}N) films prepared by cosputtering. The power generation FOM strongly depends on the scandium concentration. The FOM of Sc{sub 0.41}Al{sub 0.59}N film was 67 GPa, indicating that the FOM is five times larger than that of AlN. The FOM of Sc{sub 0.41}Al{sub 0.59}N film is higher than those of lead zirconate titanate and Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} films, which is the highest reported for any piezoelectric thin films. The high FOM of Sc{sub 0.41}Al{sub 0.59}N film is due to the high d{sub 31} and the low relative permittivity.

  19. Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making

    DOE Patents [OSTI]

    McCallum, R.W.; Branagan, D.J.

    1996-01-23T23:59:59.000Z

    A method of making a permanent magnet is disclosed wherein (1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and (2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties. 33 figs.

  20. Interlayer coupling enhancement in graphene/hexagonal boron nitride heterostructures by intercalated defects or vacancies

    SciTech Connect (OSTI)

    Park, Sohee [Department of Materials Science and Engineering, Seoul National University, Seoul 151-747 (Korea, Republic of)] [Department of Materials Science and Engineering, Seoul National University, Seoul 151-747 (Korea, Republic of); Park, Changwon [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Kim, Gunn, E-mail: gunnkim@sejong.ac.kr [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of)] [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of)

    2014-04-07T23:59:59.000Z

    Hexagonal boron nitride (hBN), a remarkable material with a two-dimensional atomic crystal structure, has the potential to fabricate heterostructures with unusual properties. We perform first-principles calculations to determine whether intercalated metal atoms and vacancies can mediate interfacial coupling and influence the structural and electronic properties of the graphene/hBN heterostructure. Metal impurity atoms (Li, K, Cr, Mn, Co, and Cu), acting as extrinsic defects between the graphene and hBN sheets, produce n-doped graphene. We also consider intrinsic vacancy defects and find that a boron monovacancy in hBN acts as a magnetic dopant for graphene, whereas a nitrogen monovacancy in hBN serves as a nonmagnetic dopant for graphene. In contrast, the smallest triangular vacancy defects in hBN are unlikely to result in significant changes in the electronic transport of graphene. Our findings reveal that a hBN layer with some vacancies or metal impurities enhances the interlayer coupling in the graphene/hBN heterostructure with respect to charge doping and electron scattering.

  1. Characterization of two-dimensional hexagonal boron nitride using scanning electron and scanning helium ion microscopy

    SciTech Connect (OSTI)

    Guo, Hongxuan, E-mail: Guo.hongxuan@nims.go.jp, E-mail: msxu@zju.edu.cn [Global Research Center for Environment and Energy Based on Nanomaterials Science National Institute for Materials Science (NIMS) 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Gao, Jianhua; Ishida, Nobuyuki [International Center for Young Scientists, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Xu, Mingsheng, E-mail: Guo.hongxuan@nims.go.jp, E-mail: msxu@zju.edu.cn [State Key Laboratory of Silicon Materials, Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Fujita, Daisuke [Advanced Key Technologies Division, Global Research Center for Environment and Energy Based on Nanomaterials Science, and International Center for Young Scientists, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-01-20T23:59:59.000Z

    Characterization of the structural and physical properties of two-dimensional (2D) materials, such as layer number and inelastic mean free path measurements, is very important to optimize their synthesis and application. In this study, we characterize the layer number and morphology of hexagonal boron nitride (h-BN) nanosheets on a metallic substrate using field emission scanning electron microscopy (FE-SEM) and scanning helium ion microscopy (HIM). Using scanning beams of various energies, we could analyze the dependence of the intensities of secondary electrons on the thickness of the h-BN nanosheets. Based on the interaction between the scanning particles (electrons and helium ions) and h-BN nanosheets, we deduced an exponential relationship between the intensities of secondary electrons and number of layers of h-BN. With the attenuation factor of the exponential formula, we calculate the inelastic mean free path of electrons and helium ions in the h-BN nanosheets. Our results show that HIM is more sensitive and consistent than FE-SEM for characterizing the number of layers and morphology of 2D materials.

  2. Lattice site location of impurities in group III nitrides using emission channeling

    E-Print Network [OSTI]

    De Vries, Bart; Wahl, Ulrich

    The group III nitrides comprise the semiconducting materials InN, GaN, AlN and their ternary alloys. During the last decade, GaN has attracted widespread attention due to its large band gap and hardness. These properties, combined with the fact that its band gap can be adjusted by alloying it with InN and AlN, make GaN a suitable material for the fabrication of optical components that operate in the blue to ultraviolet region of the electromagnetic spectrum, and for microwave and high-power applications. Indeed, during the last couple of years, GaN-based blue and violet light-emitting devices (LEDs) and laser diodes have been realized and commercialized: the violet laser diodes will even be the keystone to the next generation of optical data storage standards, Blu-ray and HD-DVD. A key aspect in device production is the incorporation of dopants that can alter the electronic, magnetic or optical properties of the host material. For example, Si is often used to generate n-type GaN, while Mg is the most frequent...

  3. Resistive switching phenomena of tungsten nitride thin films with excellent CMOS compatibility

    SciTech Connect (OSTI)

    Hong, Seok Man; Kim, Hee-Dong; An, Ho-Myoung; Kim, Tae Geun, E-mail: tgkim1@korea.ac.kr

    2013-12-15T23:59:59.000Z

    Graphical abstract: - Highlights: • The resistive switching characteristics of WN{sub x} thin films. • Excellent CMOS compatibility WN{sub x} films as a resistive switching material. • Resistive switching mechanism revealed trap-controlled space charge limited conduction. • Good endurance and retention properties over 10{sup 5} cycles, and 10{sup 5} s, respectively - Abstract: We report the resistive switching (RS) characteristics of tungsten nitride (WN{sub x}) thin films with excellent complementary metal-oxide-semiconductor (CMOS) compatibility. A Ti/WN{sub x}/Pt memory cell clearly shows bipolar RS behaviors at a low voltage of approximately ±2.2 V. The dominant conduction mechanisms at low and high resistance states were verified by Ohmic behavior and trap-controlled space-charge-limited conduction, respectively. A conducting filament model by a redox reaction explains the RS behavior in WN{sub x} films. We also demonstrate the memory characteristics during pulse operation, including a high endurance over >10{sup 5} cycles and a long retention time of >10{sup 5} s.

  4. Antifuse with a single silicon-rich silicon nitride insulating layer

    DOE Patents [OSTI]

    Habermehl, Scott D.; Apodaca, Roger T.

    2013-01-22T23:59:59.000Z

    An antifuse is disclosed which has an electrically-insulating region sandwiched between two electrodes. The electrically-insulating region has a single layer of a non-hydrogenated silicon-rich (i.e. non-stoichiometric) silicon nitride SiN.sub.X with a nitrogen content X which is generally in the range of 0

  5. Optical waveguiding properties into porous gallium nitride structures investigated by prism coupling technique

    SciTech Connect (OSTI)

    Alshehri, Bandar; Dogheche, Elhadj, E-mail: elhadj.dogheche@univ-valenciennes.fr [Institute Electronics, Microelectronics and Nanotechnology (IEMN CNRS), University of Valenciennes, Villeneuve d'Ascq (France); Lee, Seung-Min; Kang, Jin-Ho; Ryu, Sang-Wan, E-mail: sangwan@chonnam.ac.kr [Department of Physics, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Gong, Su-Hyun; Cho, Yong-Hoon [Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)

    2014-08-04T23:59:59.000Z

    In order to modulate the refractive index and the birefringence of Gallium Nitride (GaN), we have developed a chemical etching method to perform porous structures. The aim of this research is to demonstrate that optical properties of GaN can be tuned by controlling the pores density. GaN films are prepared on sapphire by metal organic chemical vapor deposition and the microstructure is characterized by transmission electron microscopy, and scanning electron microscope analysis. Optical waveguide experiment is demonstrated here to determine the key properties as the ordinary (n{sub 0}) and extraordinary (n{sub e}) refractive indices of etched structures. We report here the dispersion of refractive index for porous GaN and compare it to the bulk material. We observe that the refractive index decreases when the porous density p is increased: results obtained at 0.975??m have shown that the ordinary index n{sub 0} is 2.293 for a bulk layer and n{sub 0} is 2.285 for a pores density of 20%. This value corresponds to GaN layer with a pore size of 30?nm and inter-distance of 100?nm. The control of the refractive index into GaN is therefore fundamental for the design of active and passive optical devices.

  6. P-doping-free III-nitride high electron mobility light-emitting diodes and transistors

    SciTech Connect (OSTI)

    Li, Baikui; Tang, Xi; Chen, Kevin J., E-mail: eekjchen@ust.hk [Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Wang, Jiannong [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2014-07-21T23:59:59.000Z

    We report that a simple metal-AlGaN/GaN Schottky diode is capable of producing GaN band-edge ultraviolet emission at 3.4?eV at a small forward bias larger than ?2?V at room temperature. Based on the surface states distribution of AlGaN, a mature impact-ionization-induced Fermi-level de-pinning model is proposed to explain the underlying mechanism of the electroluminescence (EL) process. By experimenting with different Schottky metals, Ni/Au and Pt/Au, we demonstrated that this EL phenomenon is a “universal” property of metal-AlGaN/GaN Schottky diodes. Since this light-emitting Schottky diode shares the same active structure and fabrication processes as the AlGaN/GaN high electron mobility transistors, straight-forward and seamless integration of photonic and electronic functional devices has been demonstrated on doping-free III-nitride heterostructures. Using a semitransparent Schottky drain electrode, an AlGaN/GaN high electron mobility light-emitting transistor is demonstrated.

  7. Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer

    SciTech Connect (OSTI)

    Dechaumphai, Edward; Chen, Renkun, E-mail: rkchen@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2014-09-15T23:59:59.000Z

    High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbN{sub x}). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbN{sub x} as the thermometry material because it possesses both high TCR (?0.67%/K) and a low thermal conductivity (k ? 1.1 W/m?K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbN{sub x} based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher.

  8. NID Copper Sample Analysis

    SciTech Connect (OSTI)

    Kouzes, Richard T.; Zhu, Zihua

    2011-02-01T23:59:59.000Z

    The current focal point of the nuclear physics program at PNNL is the MAJORANA DEMONSTRATOR, and the follow-on Tonne-Scale experiment, a large array of ultra-low background high-purity germanium detectors, enriched in 76Ge, designed to search for zero-neutrino double-beta decay (0???). This experiment requires the use of germanium isotopically enriched in 76Ge. The DEMONSTRATOR will utilize 76Ge from Russia, but for the Tonne-Scale experiment it is hoped that an alternate technology under development at Nonlinear Ion Dynamics (NID) will be a viable, US-based, lower-cost source of separated material. Samples of separated material from NID require analysis to determine the isotopic distribution and impurities. The MAJORANA DEMONSTRATOR is a DOE and NSF funded project with a major science impact. DOE is funding NID through an SBIR grant for development of their separation technology for application to the Tonne-Scale experiment. The Environmental Molecular Sciences facility (EMSL), a DOE user facility at PNNL, has the required mass spectroscopy instruments for making these isotopic measurements that are essential to the quality assurance for the MAJORANA DEMONSTRATOR and for the development of the future separation technology required for the Tonne-Scale experiment. A sample of isotopically separated copper was provided by NID to PNNL for isotopic analysis as a test of the NID technology. The results of that analysis are reported here.

  9. Sample holder with optical features

    DOE Patents [OSTI]

    Milas, Mirko; Zhu, Yimei; Rameau, Jonathan David

    2013-07-30T23:59:59.000Z

    A sample holder for holding a sample to be observed for research purposes, particularly in a transmission electron microscope (TEM), generally includes an external alignment part for directing a light beam in a predetermined beam direction, a sample holder body in optical communication with the external alignment part and a sample support member disposed at a distal end of the sample holder body opposite the external alignment part for holding a sample to be analyzed. The sample holder body defines an internal conduit for the light beam and the sample support member includes a light beam positioner for directing the light beam between the sample holder body and the sample held by the sample support member.

  10. Sample Environment Plans and Progress

    E-Print Network [OSTI]

    Pennycook, Steve

    Sample Environment Plans and Progress at the SNS & HFIR SNS HFIR User Group Meeting American Conference on Neutron Scattering Ottawa, Canada June 26 ­ 30, 2010 Lou Santodonato Sample Environment Group our sample environment capabilities Feedback SHUG meetings User surveys Sample Environment Steering

  11. Fluid sampling tool

    DOE Patents [OSTI]

    Johnston, Roger G. (Los Alamos, NM); Garcia, Anthony R. E. (Espanola, NM); Martinez, Ronald K. (Santa Cruz, NM)

    2001-09-25T23:59:59.000Z

    The invention includes a rotatable tool for collecting fluid through the wall of a container. The tool includes a fluid collection section with a cylindrical shank having an end portion for drilling a hole in the container wall when the tool is rotated, and a threaded portion for tapping the hole in the container wall. A passageway in the shank in communication with at least one radial inlet hole in the drilling end and an opening at the end of the shank is adapted to receive fluid from the container. The tool also includes a cylindrical chamber affixed to the end of the shank opposite to the drilling portion thereof for receiving and storing fluid passing through the passageway. The tool also includes a flexible, deformable gasket that provides a fluid-tight chamber to confine kerf generated during the drilling and tapping of the hole. The invention also includes a fluid extractor section for extracting fluid samples from the fluid collecting section.

  12. Laser studies of the reactivity of NH(X{sup 3}{Sigma}{sup {minus}}) with the surface of silicon nitride

    SciTech Connect (OSTI)

    Fisher, E.R.; Ho, P.; Breiland, W.G.; Buss, R.J. [Sandia National Labs., Albuquerque, NM (United States)

    1992-11-26T23:59:59.000Z

    The reactivity of NH(X{sup 3}{Sigma}{sup {minus}}) with the surface of both a silicon nitride film and a depositing hydrogenated silicon nitride film has been measured to be essentially zero with an upper limit of 0.1 for substrate temperatures of 300-700 K. The reactivity was directly determined using spatially resolved laser-induced fluorescence of NH in a plasma-generated molecular beam incident on the surface. The NH adsorbs and then desorbs from the surface with a a spatial distribution consistent with a cosine angular distribution. No dependence of reactivity on rotational state of the NH was observed. 27 refs., 8 figs.

  13. Application of Self-Propagating High Temperature Synthesis to the Fabrication of Actinide Bearing Nitride and Other Ceramic Nuclear Fuels

    SciTech Connect (OSTI)

    John J. Moore, Marissa M. Reigel, Collin D. Donohoue

    2009-04-30T23:59:59.000Z

    The project uses an exothermic combustion synthesis reaction, termed self-propagating high-temperature synthesis (SHS), to produce high quality, reproducible nitride fuels and other ceramic type nuclear fuels (cercers and cermets, etc.) in conjunction with the fabrication of transmutation fuels. The major research objective of the project is determining the fundamental SHS processing parameters by first using manganese as a surrogate for americium to produce dense Zr-Mn-N ceramic compounds. These fundamental principles will then be transferred to the production of dense Zr-Am-N ceramic materials. A further research objective in the research program is generating fundamental SHS processing data to the synthesis of (i) Pu-Am-Zr-N and (ii) U-Pu-Am-N ceramic fuels. In this case, Ce will be used as the surrogate for Pu, Mn as the surrogate for Am, and depleted uranium as the surrogate for U. Once sufficient fundamental data has been determined for these surrogate systems, the information will be transferred to Idaho National Laboratory (INL) for synthesis of Zr-Am-N, Pu-Am-Zr-N and U-Pu-Am-N ceramic fuels. The high vapor pressures of americium (Am) and americium nitride (AmN) are cause for concern in producing nitride ceramic nuclear fuel that contains Am. Along with the problem of Am retention during the sintering phases of current processing methods, are additional concerns of producing a consistent product of desirable homogeneity, density and porosity. Similar difficulties have been experienced during the laboratory scale process development stage of producing metal alloys containing Am wherein compact powder sintering methods had to be abandoned. Therefore, there is an urgent need to develop a low-temperature or low–heat fuel fabrication process for the synthesis of Am-containing ceramic fuels. Self-propagating high temperature synthesis (SHS), also called combustion synthesis, offers such an alternative process for the synthesis of Am nitride fuels. Although SHS takes thermodynamic advantage of the high combustion temperatures of these exothermic SHS reactions to synthesize the required compounds, the very fast heating, reaction and cooling rates can kinetically generate extremely fast reaction rates and facilitate the retention of volatile species within the rapidly propagating SHS reaction front. The initial objective of the research program is to use Mn as the surrogate for Am to synthesize a reproducible, dense, high quality Zr-Mn-N ceramic compound. Having determined the fundamental SHS reaction parameters and optimized SHS processing steps using Mn as the surrogate for Am, the technology will be transferred to Idaho National Laboratory to successfully synthesize a high quality Zr-Am-N ceramic fuel.

  14. Mechanistic studies of the CVD of silicon nitride from SiF{sub 4} and NH{sub 3}

    SciTech Connect (OSTI)

    Buss, R.J.; Ho, P.

    1992-12-01T23:59:59.000Z

    An industrial process for the CVD of silicon nitride from SiF{sub 4} and NH{sub 3} was studied with a wide variety of techniques, ranging from numerical models of the coupled chemistry and fluid mechanics to experimental studies of chemical reactions. The latter includes a set of molecular beam experiments that probed the temperature and flux dependencies of the reaction of SiF{sub 4} and NH{sub 3} at the surface. These experiments showed that the CVD reactor chemistry was dominated by surface kinetics rather than gas-phase decomposition.

  15. Mechanistic studies of the CVD of silicon nitride from SiF[sub 4] and NH[sub 3

    SciTech Connect (OSTI)

    Buss, R J; Ho, P

    1992-01-01T23:59:59.000Z

    An industrial process for the CVD of silicon nitride from SiF[sub 4] and NH[sub 3] was studied with a wide variety of techniques, ranging from numerical models of the coupled chemistry and fluid mechanics to experimental studies of chemical reactions. The latter includes a set of molecular beam experiments that probed the temperature and flux dependencies of the reaction of SiF[sub 4] and NH[sub 3] at the surface. These experiments showed that the CVD reactor chemistry was dominated by surface kinetics rather than gas-phase decomposition.

  16. Specified assurance level sampling procedure

    SciTech Connect (OSTI)

    Willner, O.

    1980-11-01T23:59:59.000Z

    In the nuclear industry design specifications for certain quality characteristics require that the final product be inspected by a sampling plan which can demonstrate product conformance to stated assurance levels. The Specified Assurance Level (SAL) Sampling Procedure has been developed to permit the direct selection of attribute sampling plans which can meet commonly used assurance levels. The SAL procedure contains sampling plans which yield the minimum sample size at stated assurance levels. The SAL procedure also provides sampling plans with acceptance numbers ranging from 0 to 10, thus, making available to the user a wide choice of plans all designed to comply with a stated assurance level.

  17. Sampling for Bacteria in Wells 

    E-Print Network [OSTI]

    Lesikar, Bruce J.

    2001-11-15T23:59:59.000Z

    Sampling for Bacteria in Wells E-126 11/01 Water samples for bacteria tests must always be col- lected in a sterile container. The procedure for collect- ing a water sample is as follows: 1. Obtain a sterile container from a Health Department... immediately after collecting water sample. Refrigerate the sample and transport it to the laborato- ry (in an ice chest) as soon after collection as possible (six hours is best, but up to 30 hours). Many labs will not accept bacteria samples on Friday so check...

  18. Group-III nitride based high electron mobility transistor (HEMT) with barrier/spacer layer

    DOE Patents [OSTI]

    Chavarkar, Prashant; Smorchkova, Ioulia P.; Keller, Stacia; Mishra, Umesh; Walukiewicz, Wladyslaw; Wu, Yifeng

    2005-02-01T23:59:59.000Z

    A Group III nitride based high electron mobility transistors (HEMT) is disclosed that provides improved high frequency performance. One embodiment of the HEMT comprises a GaN buffer layer, with an Al.sub.y Ga.sub.1-y N (y=1 or y 1) layer on the GaN buffer layer. An Al.sub.x Ga.sub.1-x N (0.ltoreq.x.ltoreq.0.5) barrier layer on to the Al.sub.y Ga.sub.1-y N layer, opposite the GaN buffer layer, Al.sub.y Ga.sub.1-y N layer having a higher Al concentration than that of the Al.sub.x Ga.sub.1-x N barrier layer. A preferred Al.sub.y Ga.sub.1-y N layer has y=1 or y.about.1 and a preferred Al.sub.x Ga.sub.1-x N barrier layer has 0.ltoreq.x.ltoreq.0.5. A 2DEG forms at the interface between the GaN buffer layer and the Al.sub.y Ga.sub.1-y N layer. Respective source, drain and gate contacts are formed on the Al.sub.x Ga.sub.1-x N barrier layer. The HEMT can also comprising a substrate adjacent to the buffer layer, opposite the Al.sub.y Ga.sub.1-y N layer and a nucleation layer between the Al.sub.x Ga.sub.1-x N buffer layer and the substrate.

  19. 3 - DJ : sampling as design

    E-Print Network [OSTI]

    Patel, Sayjel Vijay

    2015-01-01T23:59:59.000Z

    3D Sampling is introduced as a new spatial craft that can be applied to architectural design, akin to how sampling is applied in the field of electronic music. Through the development of 3-DJ, a prototype design software, ...

  20. Sampling for Bacteria in Wells

    E-Print Network [OSTI]

    Lesikar, Bruce J.

    2001-11-15T23:59:59.000Z

    Sampling for Bacteria in Wells E-126 11/01 Water samples for bacteria tests must always be col- lected in a sterile container. The procedure for collect- ing a water sample is as follows: 1. Obtain a sterile container from a Health Department...

  1. ON ADAPTIVE SAMPLING Philippe Flajolet

    E-Print Network [OSTI]

    Flajolet, Philippe

    . We analyze the storage/accuracy trade--off of an adaptive sampling algorithm due to Wegman that makes. Wegman [11] has proposed an interesting alternative solution to that problem based on Adaptive Sampling 4. 2 Wegman's Adaptive Sampling Method The problem discussed here is the following. We are given

  2. Spectral Thompson Sampling Tomas Kocak

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Spectral Thompson Sampling Tom´as Koc´ak SequeL team INRIA Lille - Nord Europe France Michal Valko Thompson Sampling (TS) has surged a lot of interest due to its good empirical performance, in particular that our algorithm is com- petitive on both synthetic and real-world data. 1 Introduction Thompson Sampling

  3. Preliminary design study of small long life boiling water reactor (BWR) with tight lattice thorium nitride fuel

    SciTech Connect (OSTI)

    Trianti, Nuri, E-mail: nuri.trianti@gmail.com, E-mail: szaki@fi.itba.c.id; Su'ud, Zaki, E-mail: nuri.trianti@gmail.com, E-mail: szaki@fi.itba.c.id; Arif, Idam, E-mail: nuri.trianti@gmail.com, E-mail: szaki@fi.itba.c.id [Nuclear Physics and Biophysics Research Group, Faculty of Mathematics and Natural Science, Bandung Institute of Technology (Ganesha 10 Bandung, Indonesia) (Indonesia); Riyana, EkaSapta [Nuclear Energy Regulatory Agency (BAPETEN) (Indonesia)

    2014-09-30T23:59:59.000Z

    Neutronic performance of small long-life boiling water reactors (BWR) with thorium nitride based fuel has been performed. A recent study conducted on BWR in tight lattice environments (with a lower moderator percentage) produces small power reactor which has some specifications, i.e. 10 years operation time, power density of 19.1 watt/cc and maximum excess reactivity of about 4%. This excess reactivity value is smaller than standard reactivity of conventional BWR. The use of hexagonal geometry on the fuel cell of BWR provides a substantial effect on the criticality of the reactor to obtain a longer operating time. Supported by a tight concept lattice where the volume fraction of the fuel is greater than the moderator and fuel, Thorium Nitride give good results for fuel cell design on small long life BWR. The excess reactivity of the reactor can be reduced with the addition of gadolinium as burnable poisons. Therefore the hexagonal tight lattice fuel cell design of small long life BWR that has a criticality more than 20 years of operating time has been obtained.

  4. Europium location in the AlN: Eu green phosphor prepared by a gas-reduction-nitridation route

    SciTech Connect (OSTI)

    Yin Liangjun; Zhu Qiangqiang; Yu Wei; Hao Luyuan; Xu Xin [Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Hu Fengchun [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Hefei 230026 (China); Lee, Ming-Hsien [Department of Physics, Tamkang University, Tamsui, Taipei 251, Taiwan (China)

    2012-03-01T23:59:59.000Z

    Eu doped aluminum nitride phosphors were successfully synthesized by a novel gas-reduction-nitridation route with a reaction temperature of 1400 deg. C and a soaking time of 3 h. The obtained AlN:Eu phosphors were analyzed to elucidate the location of the Eu luminescent center. High-resolution transmission electron microscopy and transmission electron microscopy-energy dispersive spectra proved that Eu was located in the crystal lattice of AlN, then EXAFS revealed that Eu occupied a highly distorted Al site coordinated by four nitrogen at about 2.30-2.40 Angst , and the second nearest neighbors of Eu were 12 Al. This could be confirmed by the first-principles calculations based on the obtained local structure around the Eu luminescence center, where the theoretical absorption spectrum was similar to the experimental excitation spectrum. X-ray appearance near edge structure showed that Eu existed in terms of both Eu{sup 3+} and Eu{sup 2+} ions, which could be related to the limited location space of Eu. High temperature treatment could significantly increase the amount of Eu{sup 2+} by the expansion of the crystal lattice, leading to an increased green luminescence of the obtained AlN:Eu phosphors.

  5. Phonon plasmon interaction in ternary group-III-nitrides Ronny Kirste, Stefan Mohn, Markus R. Wagner, Juan S. Reparaz, and Axel Hoffmann

    E-Print Network [OSTI]

    Nabben, Reinhard

    Phonon plasmon interaction in ternary group-III-nitrides Ronny Kirste, Stefan Mohn, Markus R investigated by electron energy-loss spectroscopy J. Chem. Phys. 137, 114508 (2012) Plasmon resonances and electron transport in linear sodium atomic chains J. Appl. Phys. 112, 053707 (2012) Plasmon coupling

  6. C. Wetzel et al MRS Internet J. Nitride Semicond. Res. 10, 2 (2005) 1 Development of High Power Green Light Emitting Diode Chips

    E-Print Network [OSTI]

    Wetzel, Christian M.

    2005-01-01T23:59:59.000Z

    Power Green Light Emitting Diode Chips C. Wetzel and T. Detchprohm Future Chips Constellation Abstract The development of high emission power green light emitting diodes chips using GaInN/GaN multi production-scale implementation of this green LED die process. Keywords: nitrides, light emitting diode

  7. Hydrogen storage in carbon nitride nanobells X. D. Bai, Dingyong Zhong, G. Y. Zhang, X. C. Ma, Shuang Liu, and E. G. Wanga)

    E-Print Network [OSTI]

    Zhang, Guangyu

    Hydrogen storage in carbon nitride nanobells X. D. Bai, Dingyong Zhong, G. Y. Zhang, X. C. Ma as hydrogen adsorbent. A hydrogen storage capacity up to 8 wt % was achieved reproducibly under ambient pressure and at temperature of 300 °C. The high hydrogen storage capacity under the moderate conditions

  8. Mixing Rocksalt and Wurtzite Structure Binary Nitrides to Form Novel Ternary Alloys: ScGaN and MnGaN

    E-Print Network [OSTI]

    Mixing Rocksalt and Wurtzite Structure Binary Nitrides to Form Novel Ternary Alloys: ScGaN and Mn wurtzite structure and tetrahedral bonding, both MnN and ScN are face-centered tetragonal (fct [11]. Though challenging, growth of wurtzite MnGaN alloy by molecular beam epitaxy using radio

  9. Atomic layer structure of manganese atoms on wurtzite gallium nitride Abhijit Chinchore, Kangkang Wang, Wenzhi Lin, Jeongihm Pak, and Arthur R. Smitha

    E-Print Network [OSTI]

    Atomic layer structure of manganese atoms on wurtzite gallium nitride ,,0001¯... Abhijit Chinchore on wurtzite GaN 0001¯ . The surface is monitored using reflection high energy electron diffraction, which to grow with an abrupt interface and well- defined epitaxial orientation on top of wurtzite w -GaN. Re

  10. A Tungsten(VI) Nitride Having a W2(-N)2 Core Zachary J. Tonzetich, Richard R. Schrock,* Keith M. Wampler, Brad C. Bailey,

    E-Print Network [OSTI]

    Müller, Peter

    A Tungsten(VI) Nitride Having a W2(µ-N)2 Core Zachary J. Tonzetich, Richard R. Schrock,* Keith M-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Received September 27, 2007 The tungsten that the tungsten alkylidyne species W(C-t-Bu)(CH2-t-Bu)(OAr)2 (Ar ) 2,6-diisopropylphenyl) can be prepared readily

  11. Electrical properties and thermal stability of Pd-doped copper nitride films A. L. Ji, N. P. Lu, L. Gao, W. B. Zhang, L. G. Liao et al.

    E-Print Network [OSTI]

    Zexian, Cao

    Electrical properties and thermal stability of Pd-doped copper nitride films A. L. Ji, N. P. Lu, L/JAPIAU/v113/i4 Published by the American Institute of Physics. Related Articles Photocarrier generation) Controlling interfacial states in amorphous/crystalline LaAlO3/SrTiO3 heterostructures by electric fields Appl

  12. Growth of c-axis oriented gallium nitride thin films on an amorphous substrate by the liquid-target pulsed laser deposition technique

    E-Print Network [OSTI]

    Kwok, Hoi S.

    nitride GaN thin films with a wurtzite structure were grown on fused silica FS substrates by pulsed laser of the current directions in GaN research is to find other alter- native substrates that not only have good as a substrate for GaN film are its excellent optical transparency, low refractive index, and good mechanical

  13. Hetero-junctions of Boron Nitride and Carbon Nanotubes: Synthesis and Characterization

    SciTech Connect (OSTI)

    Yap, Yoke Khin

    2013-03-14T23:59:59.000Z

    Hetero-junctions of boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) are expected to have appealing new properties that are not available from pure BNNTs and CNTs. Theoretical studies indicate that BNNT/CNT junctions could be multifunctional and applicable as memory, spintronic, electronic, and photonics devices with tunable band structures. This will lead to energy and material efficient multifunctional devices that will be beneficial to the society. However, experimental realization of BNNT/CNT junctions was hindered by the absent of a common growth technique for BNNTs and CNTs. In fact, the synthesis of BNNTs was very challenging and may involve high temperatures (up to 3000 degree Celsius by laser ablation) and explosive chemicals. During the award period, we have successfully developed a simple chemical vapor deposition (CVD) technique to grow BNNTs at 1100-1200 degree Celsius without using dangerous chemicals. A series of common catalyst have then been identified for the synthesis of BNNTs and CNTs. Both of these breakthroughs have led to our preliminary success in growing two types of BNNT/CNT junctions and two additional new nanostructures: 1) branching BNNT/CNT junctions and 2) co-axial BNNT/CNT junctions, 3) quantum dots functionalized BNNTs (QDs-BNNTs), 4) BNNT/graphene junctions. We have started to understand their structural, compositional, and electronic properties. Latest results indicate that the branching BNNT/CNT junctions and QDs-BNNTs are functional as room-temperature tunneling devices. We have submitted the application of a renewal grant to continue the study of these new energy efficient materials. Finally, this project has also strengthened our collaborations with multiple Department of Energy�s Nanoscale Science Research Centers (NSRCs), including the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory, and the Center for Integrated Nanotechnologies (CINTs) at Sandia National Laboratories and Los Alamos National Laboratory. Results obtained during the current funding period have led to the publication of twelve peer reviewed articles, three review papers, two book and one encyclopedia chapters, and thirty eight conference/seminar presentation. One US provisional patent and one international patent have also been filed.

  14. Dual mechanical behaviour of hydrogen in stressed silicon nitride thin films

    SciTech Connect (OSTI)

    Volpi, F., E-mail: fabien.volpi@simap.grenoble-inp.fr; Braccini, M.; Pasturel, A. [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France); Devos, A. [IEMN, UMR 8520 CNRS, Avenue Poincarré - CS 60069 - 59652 Villeneuve d'Ascq Cedex (France); Raymond, G. [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France); STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex (France); Morin, P. [STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex (France)

    2014-07-28T23:59:59.000Z

    In the present article, we report a study on the mechanical behaviour displayed by hydrogen atoms and pores in silicon nitride (SiN) films. A simple three-phase model is proposed to relate the physical properties (stiffness, film stress, mass density, etc.) of hydrogenated nanoporous SiN thin films to the volume fractions of hydrogen and pores. This model is then applied to experimental data extracted from films deposited by plasma enhanced chemical vapour deposition, where hydrogen content, stress, and mass densities range widely from 11% to 30%, ?2.8 to 1.5?GPa, and 2.0 to 2.8?g/cm{sup 3}, respectively. Starting from the conventional plotting of film's Young's modulus against film porosity, we first propose to correct the conventional calculation of porosity volume fraction with the hydrogen content, thus taking into account both hydrogen mass and concentration. The weight of this hydrogen-correction is found to evolve linearly with hydrogen concentration in tensile films (in accordance with a simple “mass correction” of the film density calculation), but a clear discontinuity is observed toward compressive stresses. Then, the effective volume occupied by hydrogen atoms is calculated taking account of the bond type (N-H or Si-H bonds), thus allowing a precise extraction of the hydrogen volume fraction. These calculations applied to tensile films show that both volume fractions of hydrogen and porosity are similar in magnitude and randomly distributed against Young's modulus. However, the expected linear dependence of the Young's modulus is clearly observed when both volume fractions are added. Finally, we show that the stiffer behaviour of compressive films cannot be only explained on the basis of this (hydrogen?+?porosity) volume fraction. Indeed this stiffness difference relies on a dual mechanical behaviour displayed by hydrogen atoms against the film stress state: while they participate to the stiffness in compressive films, hydrogen atoms mainly behave like pores in tensile films where they do not participate to the film stiffness.

  15. Acceptance sampling using judgmental and randomly selected samples

    SciTech Connect (OSTI)

    Sego, Landon H.; Shulman, Stanley A.; Anderson, Kevin K.; Wilson, John E.; Pulsipher, Brent A.; Sieber, W. Karl

    2010-09-01T23:59:59.000Z

    We present a Bayesian model for acceptance sampling where the population consists of two groups, each with different levels of risk of containing unacceptable items. Expert opinion, or judgment, may be required to distinguish between the high and low-risk groups. Hence, high-risk items are likely to be identifed (and sampled) using expert judgment, while the remaining low-risk items are sampled randomly. We focus on the situation where all observed samples must be acceptable. Consequently, the objective of the statistical inference is to quantify the probability that a large percentage of the unsampled items in the population are also acceptable. We demonstrate that traditional (frequentist) acceptance sampling and simpler Bayesian formulations of the problem are essentially special cases of the proposed model. We explore the properties of the model in detail, and discuss the conditions necessary to ensure that required samples sizes are non-decreasing function of the population size. The method is applicable to a variety of acceptance sampling problems, and, in particular, to environmental sampling where the objective is to demonstrate the safety of reoccupying a remediated facility that has been contaminated with a lethal agent.

  16. Sample Residential Program Term Sheet

    Broader source: Energy.gov [DOE]

    A sample for defining and elaborating on the specifics of a clean energy loan program. Author: U.S. Department of Energy

  17. IWTU Process Sample Analysis Report

    SciTech Connect (OSTI)

    Nick Soelberg

    2013-04-01T23:59:59.000Z

    CH2M-WG Idaho (CWI) requested that Battelle Energy Alliance (BEA) analyze various samples collected during June – August 2012 at the Integrated Waste Treatment Facility (IWTU). Samples of IWTU process materials were collected from various locations in the process. None of these samples were radioactive. These samples were collected and analyzed to provide more understanding of the compositions of various materials in the process during the time of the process shutdown that occurred on June 16, 2012, while the IWTU was in the process of nonradioactive startup.

  18. Electronic stiffness of a superconducting niobium nitride single crystal under pressure Xiao-Jia Chen, Viktor V. Struzhkin, Zhigang Wu, Ronald E. Cohen, Simon Kung,* Ho-kwang Mao, and Russell J. Hemley

    E-Print Network [OSTI]

    Wu, Zhigang

    Electronic stiffness of a superconducting niobium nitride single crystal under pressure Xiao report a quantitative study of pressure effects on the superconducting transition temperature Tc transition temperatures Tc's of materials, pur- suing new classes of superconductors and shedding light

  19. Defining And Characterizing Sample Representativeness For DWPF Melter Feed Samples

    SciTech Connect (OSTI)

    Shine, E. P.; Poirier, M. R.

    2013-10-29T23:59:59.000Z

    Representative sampling is important throughout the Defense Waste Processing Facility (DWPF) process, and the demonstrated success of the DWPF process to achieve glass product quality over the past two decades is a direct result of the quality of information obtained from the process. The objective of this report was to present sampling methods that the Savannah River Site (SRS) used to qualify waste being dispositioned at the DWPF. The goal was to emphasize the methodology, not a list of outcomes from those studies. This methodology includes proven methods for taking representative samples, the use of controlled analytical methods, and data interpretation and reporting that considers the uncertainty of all error sources. Numerous sampling studies were conducted during the development of the DWPF process and still continue to be performed in order to evaluate options for process improvement. Study designs were based on use of statistical tools applicable to the determination of uncertainties associated with the data needs. Successful designs are apt to be repeated, so this report chose only to include prototypic case studies that typify the characteristics of frequently used designs. Case studies have been presented for studying in-tank homogeneity, evaluating the suitability of sampler systems, determining factors that affect mixing and sampling, comparing the final waste glass product chemical composition and durability to that of the glass pour stream sample and other samples from process vessels, and assessing the uniformity of the chemical composition in the waste glass product. Many of these studies efficiently addressed more than one of these areas of concern associated with demonstrating sample representativeness and provide examples of statistical tools in use for DWPF. The time when many of these designs were implemented was in an age when the sampling ideas of Pierre Gy were not as widespread as they are today. Nonetheless, the engineers and statisticians used carefully thought out designs that systematically and economically provided plans for data collection from the DWPF process. Key shared features of the sampling designs used at DWPF and the Gy sampling methodology were the specification of a standard for sample representativeness, an investigation that produced data from the process to study the sampling function, and a decision framework used to assess whether the specification was met based on the data. Without going into detail with regard to the seven errors identified by Pierre Gy, as excellent summaries are readily available such as Pitard [1989] and Smith [2001], SRS engineers understood, for example, that samplers can be biased (Gy?s extraction error), and developed plans to mitigate those biases. Experiments that compared installed samplers with more representative samples obtained directly from the tank may not have resulted in systematically partitioning sampling errors into the now well-known error categories of Gy, but did provide overall information on the suitability of sampling systems. Most of the designs in this report are related to the DWPF vessels, not the large SRS Tank Farm tanks. Samples from the DWPF Slurry Mix Evaporator (SME), which contains the feed to the DWPF melter, are characterized using standardized analytical methods with known uncertainty. The analytical error is combined with the established error from sampling and processing in DWPF to determine the melter feed composition. This composition is used with the known uncertainty of the models in the Product Composition Control System (PCCS) to ensure that the wasteform that is produced is comfortably within the acceptable processing and product performance region. Having the advantage of many years of processing that meets the waste glass product acceptance criteria, the DWPF process has provided a considerable amount of data about itself in addition to the data from many special studies. Demonstrating representative sampling directly from the large Tank Farm tanks is a difficult, if not unsolvable enterprise due to li

  20. Hazard Sampling Dialog General Layout

    E-Print Network [OSTI]

    Zhang, Tao

    1 Hazard Sampling Dialog General Layout The dialog's purpose is to display information about the hazardous material being sampled by the UGV so either the system or the UV specialist can identify the risk level of the hazard. The dialog is associated with the hazmat reading icons (Table 1). Components

  1. Database Sampling with Functional Dependencies

    E-Print Network [OSTI]

    Riera, Jesús Bisbal

    Database Sampling with Functional Dependencies Jes´us Bisbal, Jane Grimson Department of Computer there is a need to prototype the database which the applications will use when in operation. A prototype database can be built by sampling data from an existing database. Including relevant semantic information when

  2. BLOOD SAMPLING SYSTEM TROUBLESHOOTING TIPS

    E-Print Network [OSTI]

    Kay, Mark A.

    SAFESET TM BLOOD SAMPLING SYSTEM SAFESETTM TROUBLESHOOTING TIPS TO PREVENT BLOOD BACKING UP IN LINE that all air bubbles have been eliminated when priming o Invert and tap blood sampling ports to remove air volume o Reinfuse the patient's blood slowly, no faster than 1mL per second, by pressing the plunger back

  3. Sandia Energy - Light Creation Materials

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ZnO, will be important. AlGaInN Materials LEDs based on gallium nitride (GaN) and ternary alloys with indium (InGaN) and aluminum (AlGaN) as well as quaternary alloys (AlGaInN) can...

  4. Sandia National Laboratories: Light Creation Materials

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for example ZnO, will be important. AlGaInN Materials LEDs based on gallium nitride (GaN) and ternary alloys with indium (InGaN) and aluminum (AlGaN) as well as quaternary...

  5. Sample push-out fixture

    DOE Patents [OSTI]

    Biernat, John L. (Scotia, NY)

    2002-11-05T23:59:59.000Z

    This invention generally relates to the remote removal of pelletized samples from cylindrical containment capsules. V-blocks are used to receive the samples and provide guidance to push out rods. Stainless steel liners fit into the v-channels on the v-blocks which permits them to be remotely removed and replaced or cleaned to prevent cross contamination between capsules and samples. A capsule holder securely holds the capsule while allowing manual up/down and in/out movement to align each sample hole with the v-blocks. Both end sections contain identical v-blocks; one that guides the drive out screw and rods or manual push out rods and the other to receive the samples as they are driven out of the capsule.

  6. Compact, Interactive Electric Vehicle Charger: Gallium-Nitride Switch Technology for Bi-directional Battery-to-Grid Charger Applications

    SciTech Connect (OSTI)

    None

    2010-10-01T23:59:59.000Z

    ADEPT Project: HRL Laboratories is using gallium nitride (GaN) semiconductors to create battery chargers for electric vehicles (EVs) that are more compact and efficient than traditional EV chargers. Reducing the size and weight of the battery charger is important because it would help improve the overall performance of the EV. GaN semiconductors process electricity faster than the silicon semiconductors used in most conventional EV battery chargers. These high-speed semiconductors can be paired with lighter-weight electrical circuit components, which helps decrease the overall weight of the EV battery charger. HRL Laboratories is combining the performance advantages of GaN semiconductors with an innovative, interactive battery-to-grid energy distribution design. This design would support 2-way power flow, enabling EV battery chargers to not only draw energy from the power grid, but also store and feed energy back into it.

  7. Effects of boron-nitride substrates on Stone-Wales defect formation in graphene: An ab initio molecular dynamics study

    SciTech Connect (OSTI)

    Jin, K.; Xiao, H. Y. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Zhang, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Weber, W. J., E-mail: wjweber@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-05-19T23:59:59.000Z

    Ab initio molecular dynamics simulations are performed to investigate the effects of a boron nitride (BN) substrate on Stone-Wales (SW) defect formation and recovery in graphene. It is found that SW defects can be created by an off-plane recoil atom that interacts with the BN substrate. A mechanism with complete bond breakage for formation of SW defects in suspended graphene is also revealed for recoils at large displacement angles. In addition, further irradiation can result in recovery of the SW defects through a bond rotation mechanism in both graphene and graphene/BN, and the substrate has little effect on the recovery process. This study indicates that the BN substrate enhances the irradiation resistance of graphene.

  8. Time resolved measurement of film growth during reactive high power pulsed magnetron sputtering (HIPIMS) of titanium nitride

    E-Print Network [OSTI]

    Mitschker, Felix; Benedikt, Jan; Maszl, Christian; von Keudell, Achim

    2013-01-01T23:59:59.000Z

    The growth rate during reactive high power pulsed magnetron sputtering (HIPIMS) of titanium nitride is measured with a temporal resolution of up to 25 us using a rotating shutter concept. According to that concept a 200 um slit is rotated in front of the substrate synchronous with the HIPIMS pulses. Thereby, the growth flux is laterally distributed over the substrate. By measuring the resulting deposition profile with profilometry and with x-ray photoelectron spectroscopy, the temporal variation of the titanium and nitrogen growth flux per pulse is deduced. The analysis reveals that film growth occurs mainly during a HIPIMS pulse, with the growth rate following the HIPIMS phases ignition, current rise, gas rarefaction, plateau and afterglow. The growth fluxes of titanium and nitrogen follow slightly different behaviors with titanium dominating at the beginning of the HIPIMS pulse and nitrogen at the end of the pulse. This is explained by the gas rarefaction effect resulting in a dense initial metal plasma and...

  9. Controlled polarity of sputter-deposited aluminum nitride on metals observed by aberration corrected scanning transmission electron microscopy

    SciTech Connect (OSTI)

    Harumoto, T. [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1-S8-6 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Department of Materials Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Sannomiya, T.; Matsukawa, Y.; Muraishi, S.; Shi, J.; Nakamura, Y. [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1-S8-6 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Sawada, H. [Japan Electron Optics Laboratory (JEOL) Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Tanaka, T.; Tanishiro, Y.; Takayanagi, K. [Department of Physics, Tokyo Institute of Technology, 2-12-1-H-51 O-okayama, Meguro-ku, Tokyo 152-8551 (Japan)

    2013-02-28T23:59:59.000Z

    The polarity determination process of sputter-deposited aluminum nitride (AlN) on metals has been analyzed using aberration corrected atomic resolution scanning transmission electron microscope. Direct growth of c-axis orientated AlN on face centered cubic metals (fcc) (111) with the local epitaxy has been observed, and the polarity was determined at the AlN/metal interface. We found that the AlN polarity can be controlled by the base metal layer: N-polarity AlN grows on Pt(111) while Al-polarity AlN forms on Al(111). Based on these results, the growth mechanism of AlN on metals is discussed.

  10. Low-temperature growth of gallium nitride films by inductively coupled-plasma-enhanced reactive magnetron sputtering

    SciTech Connect (OSTI)

    Ni, Chih-Jui; Chau-Nan Hong, Franklin, E-mail: hong@mail.ncku.edu.tw [Department of Chemical Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2014-05-15T23:59:59.000Z

    Gallium nitride (GaN) films were grown on sapphire substrate by reactive magnetron sputtering. Inductively coupled-plasma (ICP) source was installed between the substrate holder and the sputtering target to increase the plasma density and the degree of ionization of nitrogen gas. Liquid Ga and Ar/N{sub 2} were used as the sputtering target and sputtering gases, respectively. X-ray diffraction measurements confirmed that the authors could grow high quality GaN crystallites at 500?°C. However, the crystalline GaN (0002) peak remained even by lowering the growth temperature down to 300?°C. The N:Ga ratio of the film grown at 500?°C was almost 1:1, and the nitrogen composition became higher toward the 1:1 N:Ga ratio with increasing the growth temperature. The high degree of ionization induced by ICP source was essential to the growth of high crystalline quality GaN films.

  11. Effects of ternary mixed crystal and size on optical phonons in wurtzite nitride core-shell nanowires

    SciTech Connect (OSTI)

    Li, J.; Guan, J. Y.; Zhang, S. F.; Ban, S. L.; Qu, Y., E-mail: quyuan@imu.edu.cn [School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021 (China)

    2014-04-21T23:59:59.000Z

    Within the framework of dielectric continuum and Loudon's uniaxial crystal models, existence conditions dependent on components and frequencies for optical phonons in wurtzite nitride core-shell nanowires (CSNWs) are discussed to obtain dispersion relations and electrostatic potentials of optical phonons in In{sub x}Ga{sub 1?x}N/GaN CSNWs. The results show that there may be four types of optical phonons in In{sub x}Ga{sub 1?x}N/GaN CSNWs for a given ternary mixed crystal (TMC) component due to the phonon dispersion anisotropy. This property is analogous to wurtzite planar heterojunctions. Among the optical phonons, there are two types of quasi-confined optical (QCO) phonons (named, respectively, as QCO-A and QCO-B), one type of interface (IF) phonons and propagating (PR) phonons existing in certain component and frequency domains while the dispersion relations and electrostatic potentials of same type of optical phonons vary with components. Furthermore, the size effect on optical phonons in CSNWs is also discussed. The dispersion relations of IF and QCO-A are independent of the boundary location of CSNWs. Meanwhile, dispersion relations and electrostatic potentials of QCO-B and PR phonons vary obviously with size, especially, when the ratio of a core radius to a shell radius is small, and dispersion relation curves of PR phonons appear to be close to each other, whereas, this phenomenon disappears when the ratio becomes large. Based on our conclusions, one can further discuss photoelectric properties in nitride CSNWs consisting of TMCs associated with optical phonons.

  12. The etching process of boron nitride by alkali and alkaline earth fluorides under high pressure and high temperature

    SciTech Connect (OSTI)

    Guo, W., E-mail: guowei1982cry@163.com [College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Ma, H.A.; Jia, X. [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China)

    2014-03-01T23:59:59.000Z

    Graphical abstract: - Highlights: • Appropriate etch processes of hBN and cBN under HPHT are proposed. • The degree of the crystallization of hBN was decreased. • A special cBN growth mechanism with a triangular unit is proposed. • Plate-shape cBN crystals with large ratio of length to thickness were obtained. • A strategy provides useful guidance for controlling the cBN morphology. - Abstract: Some new etching processes of hexagonal boron nitride (hBN) and cubic boron nitride (cBN) under high pressure and high temperature in the presence of alkali and alkaline earth fluorides have been discussed. It is found that hBN is etched distinctly by alkali and alkaline earth fluorides and the morphology of hBN is significantly changed from plate-shape to spherical-shape. Based on the “graphitization index” values of hBN, the degree of the crystallization of hBN under high pressure and high temperature decreases in the sequence of LiF > CaF{sub 2} > MgF{sub 2}. This facilitates the formation of high-quality cBN single crystals. Different etch steps, pits, and islands are observed on cBN surface, showing the strong etching by alkali and alkaline earth fluorides and the tendency of layer-by-layer growth. A special layer growth mechanism of cBN with a triangular unit has been found. Furthermore, the morphologies of cBN crystals are apparently affected by a preferential surface etching of LiF, CaF{sub 2} and MgF{sub 2}. Respectively, the plate-shape and tetrahedral cBN crystals can be obtained in the presence of different alkali and alkaline earth fluorides.

  13. Sample Business Plan Framework 3

    Broader source: Energy.gov [DOE]

    U.S. Department of Energy Better Buildings Neighborhood Program: Sample Business Plan Framework 1: A program seeking to continue operations in the post-grant period as a not-for-profit (NGO) entity.

  14. Sample Business Plan Framework 2

    Broader source: Energy.gov [DOE]

    U.S. Department of Energy Better Buildings Neighborhood Program: Sample Business Plan Framework 1: A program seeking to continue operations in the post-grant period as a not-for-profit (NGO) entity.

  15. Sample Business Plan Framework 4

    Broader source: Energy.gov [DOE]

    U.S. Department of Energy Better Buildings Neighborhood Program: Sample Business Plan Framework 1: A program seeking to continue operations in the post-grant period as a not-for-profit (NGO) entity.

  16. Sample Business Plan Framework 1

    Broader source: Energy.gov [DOE]

    U.S. Department of Energy Better Buildings Neighborhood Program: Sample Business Plan Framework 1: A program seeking to continue operations in the post-grant period as a not-for-profit (NGO) entity.

  17. Size dependent optical properties of Si quantum dots in Si-rich nitride/Si{sub 3}N{sub 4} superlattice synthesized by magnetron sputtering

    SciTech Connect (OSTI)

    So, Yong-Heng; Huang, Shujuan; Conibeer, Gavin; Green, Martin A. [ARC Photovoltaics Centre of Excellence, University of New South Wales, Sydney, New South Wales 2052 (Australia); Gentle, Angus [Physics and Advanced Materials, University of Technology Sydney, P. O. Box 123, Broadway, New South Wales 2007 (Australia)

    2011-03-15T23:59:59.000Z

    A spectroscopic ellipsometry compatible approach is reported for the optical study of Si quantum dots (QDs) in Si-rich nitride/silicon nitride (SRN/Si{sub 3}N{sub 4}) superlattice, which based on Tauc-Lorentz model and Bruggeman effective medium approximation. It is shown that the optical constants and dielectric functions of Si QDs are strongly size dependent. The suppressed imaginary dielectric function of Si QDs exhibits a single broad peak analogous to amorphous Si, which centered between the transition energies E{sub 1} and E{sub 2} of bulk crystalline Si and blue shifted toward E{sub 2} as the QD size reduced. A bandgap expansion observed by the TL model when the size of Si QD reduced is in good agreement with the PL measurement. The bandgap expansion with the reduction of Si QD size is well supported by the first-principles calculations based on quantum confinement.

  18. Review of corrosion behavior of ceramic heat exchanger materals: Corrosion characteristics of silicon carbide and silicon nitride. Final report, September 11, 1992--March 11, 1993

    SciTech Connect (OSTI)

    Munro, R.G.; Dapkunas, S.J.

    1993-09-01T23:59:59.000Z

    The present work is a review of the substantial effort that has been made to measure and understand the effects of corrosion with respect to the properties, performance, and durability of various forms of silicon carbide and silicon nitride. The review encompasses corrosion in diverse environments, usually at temperatures of 1000C or higher. The environments include dry and moist oxygen, mixtures of hot gaseous vapors, molten salts, molten metals, and complex environments pertaining to coal ashes and slags.

  19. Sampling Report for August 15, 2014 WIPP Samples

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOrigin ofEnergy atLLC - FE DKT. 10-160-LNG - ORDERSTATE0-1ofEnergy SampleSample of

  20. Reference Potential source Data type Sampling site Type of samples Number of samples Method of source

    E-Print Network [OSTI]

    Meskhidze, Nicholas

    samples for Saharan dust from Libya back trajectory analysis Kandler et al. 2009 PSA NAF-2 Illite NAF-4 Illite/kaolinite ratio Chlorite/kaolinite ratio Carbonate content Libya (here: central

  1. Sample rotating turntable kit for infrared spectrometers

    DOE Patents [OSTI]

    Eckels, Joel Del (Livermore, CA); Klunder, Gregory L. (Oakland, CA)

    2008-03-04T23:59:59.000Z

    An infrared spectrometer sample rotating turntable kit has a rotatable sample cup containing the sample. The infrared spectrometer has an infrared spectrometer probe for analyzing the sample and the rotatable sample cup is adapted to receive the infrared spectrometer probe. A reflectance standard is located in the rotatable sample cup. A sleeve is positioned proximate the sample cup and adapted to receive the probe. A rotator rotates the rotatable sample cup. A battery is connected to the rotator.

  2. Inertial impaction air sampling device

    DOE Patents [OSTI]

    Dewhurst, K.H.

    1987-12-10T23:59:59.000Z

    An inertial impactor to be used in an air sampling device for collection of respirable size particles in ambient air which may include a graphite furnace as the impaction substrate in a small-size, portable, direct analysis structure that gives immediate results and is totally self-contained allowing for remote and/or personal sampling. The graphite furnace collects suspended particles transported through the housing by means of the air flow system, and these particles may be analyzed for elements, quantitatively and qualitatively, by atomic absorption spectrophotometry. 3 figs.

  3. Inertial impaction air sampling device

    DOE Patents [OSTI]

    Dewhurst, K.H.

    1990-05-22T23:59:59.000Z

    An inertial impactor is designed which is to be used in an air sampling device for collection of respirable size particles in ambient air. The device may include a graphite furnace as the impaction substrate in a small-size, portable, direct analysis structure that gives immediate results and is totally self-contained allowing for remote and/or personal sampling. The graphite furnace collects suspended particles transported through the housing by means of the air flow system, and these particles may be analyzed for elements, quantitatively and qualitatively, by atomic absorption spectrophotometry. 3 figs.

  4. Spent nuclear fuel sampling strategy

    SciTech Connect (OSTI)

    Bergmann, D.W.

    1995-02-08T23:59:59.000Z

    This report proposes a strategy for sampling the spent nuclear fuel (SNF) stored in the 105-K Basins (105-K East and 105-K West). This strategy will support decisions concerning the path forward SNF disposition efforts in the following areas: (1) SNF isolation activities such as repackaging/overpacking to a newly constructed staging facility; (2) conditioning processes for fuel stabilization; and (3) interim storage options. This strategy was developed without following the Data Quality Objective (DQO) methodology. It is, however, intended to augment the SNF project DQOS. The SNF sampling is derived by evaluating the current storage condition of the SNF and the factors that effected SNF corrosion/degradation.

  5. Methods and Materials Sample Collection

    E-Print Network [OSTI]

    by Greenwood (1958). A 1.5-inch (3.8 em) mesh liner was laced into the cod end to retain small specimens which reported that Alaska pollock \\yas the principal species taken by these Japanese fisheries. However from flatfish samples collected in 1949 were reported by Mosher (1954); the Soviet collections of 1957

  6. Sample Internship Posting Department Name

    E-Print Network [OSTI]

    Bordenstein, Seth

    Sample Internship Posting Department Name: Internship Title: Location: Description of Organization are examples from other internship postings Interns will: · Analyze potential investments · Shadow team members(s) in ________ is desirable For a list of majors see http://admissions.vanderbilt.edu/major Internship Period: The following

  7. Waste tank characterization sampling limits

    SciTech Connect (OSTI)

    Tusler, L.A.

    1994-09-02T23:59:59.000Z

    This document is a result of the Plant Implementation Team Investigation into delayed reporting of the exotherm in Tank 241-T-111 waste samples. The corrective actions identified are to have immediate notification of appropriate Tank Farm Operations Shift Management if analyses with potential safety impact exceed established levels. A procedure, WHC-IP-0842 Section 12.18, ``TWRS Approved Sampling and Data Analysis by Designated Laboratories`` (WHC 1994), has been established to require all tank waste sampling (including core, auger and supernate) and tank vapor samples be performed using this document. This document establishes levels for specified analysis that require notification of the appropriate shift manager. The following categories provide numerical values for analysis that may indicate that a tank is either outside the operating specification or should be evaluated for inclusion on a Watch List. The information given is intended to translate an operating limit such as heat load, expressed in Btu/hour, to an analysis related limit, in this case cesium-137 and strontium-90 concentrations. By using the values provided as safety flags, the analytical laboratory personnel can notify a shift manager that a tank is in potential violation of an operating limit or that a tank should be considered for inclusion on a Watch List. The shift manager can then take appropriate interim measures until a final determination is made by engineering personnel.

  8. Licensing Guide and Sample License

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TEI:HNOL06Y TRANSFER WORKIN6 6ROUP Lic:eniing Guide and Sample Lic:enie ICan.u City Plan I OFermilab OAK RIDGE Nuioul.

  9. Environmental Analysis & Policy: Sample Pathway

    E-Print Network [OSTI]

    Goldberg, Bennett

    Environmental Analysis & Policy: Sample Pathway Semester I Semester II Freshman Year CGS Core CGS Sustainable Development OR Spring GE 425 U.S. Environmental Policy (Senior) GE 309 Intermediate Env Analysis (Fall) EAP Elective Summer Environmental Internship Senior Year GE 420 Env Policy Analysis 4 th Semester

  10. Quantum rejection sampling Maris Ozols

    E-Print Network [OSTI]

    Cerf, Nicolas

    generation prob- lem. We exhibit an algorithm, which we call quantum rejec- tion sampling, and analyze its technical innovation is an extension of the automorphism principle to continuous groups that arise or to redistribute to lists, requires prior specific permission and/or a fee. ITCS '12, January 08 - 10, 2012

  11. AUTOMATING GROUNDWATER SAMPLING AT HANFORD

    SciTech Connect (OSTI)

    CONNELL CW; HILDEBRAND RD; CONLEY SF; CUNNINGHAM DE

    2009-01-16T23:59:59.000Z

    Until this past October, Fluor Hanford managed Hanford's integrated groundwater program for the U.S. Department of Energy (DOE). With the new contract awards at the Site, however, the CH2M HILL Plateau Remediation Company (CHPRC) has assumed responsibility for the groundwater-monitoring programs at the 586-square-mile reservation in southeastern Washington State. These programs are regulated by the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). The purpose of monitoring is to track existing groundwater contamination from past practices, as well as other potential contamination that might originate from RCRA treatment, storage, and disposal (TSD) facilities. An integral part of the groundwater-monitoring program involves taking samples of the groundwater and measuring the water levels in wells scattered across the site. More than 1,200 wells are sampled each year. Historically, field personnel or 'samplers' have been issued pre-printed forms that have information about the well(s) for a particular sampling evolution. This information is taken from the Hanford Well Information System (HWIS) and the Hanford Environmental Information System (HEIS)--official electronic databases. The samplers used these hardcopy forms to document the groundwater samples and well water-levels. After recording the entries in the field, the samplers turned the forms in at the end of the day and the collected information was posted onto a spreadsheet that was then printed and included in a log book. The log book was then used to make manual entries of the new information into the software application(s) for the HEIS and HWIS databases. This is a pilot project for automating this tedious process by providing an electronic tool for automating water-level measurements and groundwater field-sampling activities. The automation will eliminate the manual forms and associated data entry, improve the accuracy of the information recorded, and enhance the efficiency and sampling capacity of field personnel. The goal of the effort is to eliminate 100 percent of the manual input to the database(s) and replace the management of paperwork by the field and clerical personnel with an almost entirely electronic process. These activities will include the following: scheduling the activities of the field teams, electronically recording water-level measurements, electronically logging and filing Groundwater Sampling Reports (GSR), and transferring field forms into the site-wide Integrated Document Management System (IDMS).

  12. Environmental surveillance master sampling schedule

    SciTech Connect (OSTI)

    Bisping, L E

    1992-01-01T23:59:59.000Z

    Environmental surveillance of the Hanford Site and surrounding areas is conducted by the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE). This document contains the planned schedule for routine sample collection for the Surface Environmental Surveillance Project (SESP) and Ground-Water Monitoring Project. Samples for radiological analyses include Air-Particulate Filter, gases and vapor; Water/Columbia River, Onsite Pond, Spring, Irrigation, and Drinking; Foodstuffs/Animal Products including Whole Milk, Poultry and Eggs, and Beef; Foodstuffs/Produce including Leafy Vegetables, Vegetables, and Fruit; Foodstuffs/Farm Products including Wine, Wheat and Alfalfa; Wildlife; Soil; Vegetation; and Sediment. Direct Radiation Measurements include Terrestrial Locations, Columbia River Shoreline Locations, and Onsite Roadway, Railway and Aerial, Radiation Surveys.

  13. Adaptive Sampling in Hierarchical Simulation

    SciTech Connect (OSTI)

    Knap, J; Barton, N R; Hornung, R D; Arsenlis, A; Becker, R; Jefferson, D R

    2007-07-09T23:59:59.000Z

    We propose an adaptive sampling methodology for hierarchical multi-scale simulation. The method utilizes a moving kriging interpolation to significantly reduce the number of evaluations of finer-scale response functions to provide essential constitutive information to a coarser-scale simulation model. The underlying interpolation scheme is unstructured and adaptive to handle the transient nature of a simulation. To handle the dynamic construction and searching of a potentially large set of finer-scale response data, we employ a dynamic metric tree database. We study the performance of our adaptive sampling methodology for a two-level multi-scale model involving a coarse-scale finite element simulation and a finer-scale crystal plasticity based constitutive law.

  14. Offline solid phase microextraction sampling system

    DOE Patents [OSTI]

    Harvey, Chris A. (French Camp, CA)

    2008-12-16T23:59:59.000Z

    An offline solid phase microextraction (SPME) sampling apparatus for enabling SPME samples to be taken a number of times from a previously collected fluid sample (e.g. sample atmosphere) stored in a fused silica lined bottle which keeps volatile organics in the fluid sample stable for weeks at a time. The offline SPME sampling apparatus has a hollow body surrounding a sampling chamber, with multiple ports through which a portion of a previously collected fluid sample may be (a) released into the sampling chamber, (b) SPME sampled to collect analytes for subsequent GC analysis, and (c) flushed/purged using a fluidically connected vacuum source and purging fluid source to prepare the sampling chamber for additional SPME samplings of the same original fluid sample, such as may have been collected in situ from a headspace.

  15. Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

    DOE Patents [OSTI]

    Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

    2003-09-23T23:59:59.000Z

    Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

  16. FP-LAPW investigation of electronic, magnetic, elastic and thermal properties of Fe-doped zirconium nitride

    SciTech Connect (OSTI)

    Sirajuddeen, M. Mohamed Sheik, E-mail: msheiksiraj@bsauniv.ac.in; Banu, I. B. Shameem [Department of Physics, B. S. Abdur Rahman University, Chennai-600 048 (India)

    2014-05-15T23:59:59.000Z

    Full Potential- Linear Augmented Plane Wave (FP-LAPW) method has been employed to study the electronic, magnetic, elastic and thermal properties of Fe-doped Zirconium nitride. In this work, Fe-atoms were doped into the super cell of ZrN in doping concentrations of 12.5%, 25% and 37.5% to replace Zr atoms. Electronic properties such as band structure and DOS were plotted and compared for the doped compounds. Charge density contours were plotted for all the doped compounds. The non-magnetic ZrN doped in different Fe concentrations were found to be ferromagnetic. Magnetic moments have been calculated and compared. Elastic properties have been studied and compared with electronic properties. Appearance of magnetic ordering and its influence with the elastic properties have been reported. Impact of 3d states of Fe in DOS plot on the elastic nature of the compounds has been highlighted. Thermal properties such as Debye temperature and molar heat capacities at low temperature have been determined. Debye temperature is found to decrease with higher doping concentrations. Molar heat capacities are found to increase with higher concentrations of Fe atoms.

  17. Temperature dependence of the reactivity of OH(X[sup 2][Pi]) with oxidized silicon nitride and PMMA film surfaces

    SciTech Connect (OSTI)

    Fisher, E.R.; Ho, P.; Breiland, W.G.; Buss, R.J. (Sandia National Lab., Albuquerque, NM (United States))

    1993-10-07T23:59:59.000Z

    The reactivity of OH(X[sup 2][Pi]) with the surface of both an oxidized silicon nitride film and a poly(methyl methacrylate) (PMMA) film is measured to be 0.60 [+-] 0.05 at room temperature. The reactivity of OH with oxidized Si[sub 3]N[sub 4] substrates displays an inverse dependence on substrate temperature, decreasing to approximately 0 at temperatures above 500 K. The reactivity is determined directly using spatially resolved laser-induced fluorescence of OH in a plasma-generated molecular beam incident on the surface. The desorbed OH has a cosine angular distribution. No evidence for a dependence of reactivity on rotational state of the OH was observed. The reactivity of OH with a PMMA film is also explored using different gas compositions in the plasma beam source. Exposure of the PMMA surface to O[sub 2] and O[sub 2]/CF[sub 4] plasmas results in the generation and desorption of OH. 45 refs., 6 figs., 1 tab.

  18. Microsoft Word - JWS Sample.doc

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    7 SAMPLE ONLY REV2021005 SAMPLE ONLY Joint Work Statement For CRADA No. Sample BETWEEN U. S. Department of Energy Naval Petroleum Reserve No. 3 Rocky Mountain Oilfield Testing...

  19. Synchronized sampling improves fault location

    SciTech Connect (OSTI)

    Kezunovic, M. [Texas A and M Univ., College Station, TX (United States)] [Texas A and M Univ., College Station, TX (United States); Perunicic, B. [Lamar Univ., Beaumont, TX (United States)] [Lamar Univ., Beaumont, TX (United States)

    1995-04-01T23:59:59.000Z

    Transmission line faults must be located accurately to allow maintenance crews to arrive at the scene and repair the faulted section as soon as possible. Rugged terrain and geographical layout cause some sections of power transmission lines to be difficult to reach. In the past, a variety of fault location algorithms were introduced as either an add-on feature in protective relays or stand-alone implementation in fault locators. In both cases, the measurements of current and voltages were taken at one terminal of a transmission line only. Under such conditions, it may become difficult to determine the fault location accurately, since data from other transmission line ends are required for more precise computations. In the absence of data from the other end, existing algorithms have accuracy problems under several circumstances, such as varying switching and loading conditions, fault infeed from the other end, and random value of fault resistance. Most of the one-end algorithms were based on estimation of voltage and current phasors. The need to estimate phasors introduces additional difficulty in high-speed tripping situations where the algorithms may not be fast enough in determining fault location accurately before the current signals disappear due to the relay operation and breaker opening. This article introduces a unique concept of high-speed fault location that can be implemented either as a simple add-on to the digital fault recorders (DFRs) or as a stand-alone new relaying function. This advanced concept is based on the use of voltage and current samples that are synchronously taken at both ends of a transmission line. This sampling technique can be made readily available in some new DFR designs incorporating receivers for accurate sampling clock synchronization using the satellite Global Positioning System (GPS).

  20. Crystal structure and magnetic properties of '{alpha} Prime Prime -Fe{sub 16}N{sub 2}' containing residual {alpha}-Fe prepared by low-temperature ammonia nitridation

    SciTech Connect (OSTI)

    Yamashita, S.; Masubuchi, Y. [Faculty of Engineering, Hokkaido University N13W8, Kita-ku, Sapporo 060-8628 (Japan)] [Faculty of Engineering, Hokkaido University N13W8, Kita-ku, Sapporo 060-8628 (Japan); Nakazawa, Y.; Okayama, T.; Tsuchiya, M. [Automobile R and D Center, Tochigi, Honda R and D Co. LTD., Shimotakanezawa 4630, Haga, Tochigi 321-3393 (Japan)] [Automobile R and D Center, Tochigi, Honda R and D Co. LTD., Shimotakanezawa 4630, Haga, Tochigi 321-3393 (Japan); Kikkawa, S., E-mail: kikkawa@eng.hokudai.ac.jp [Faculty of Engineering, Hokkaido University N13W8, Kita-ku, Sapporo 060-8628 (Japan)

    2012-10-15T23:59:59.000Z

    Slight enhancement of saturation magnetization to 219 A m{sup 2} kg{sup -1} was observed from 199 A m{sup 2} kg{sup -1} for the original {alpha}-Fe on the intermediate nitrided mixture of '{alpha} Prime Prime -Fe{sub 16}N{sub 2}' with residual {alpha}-Fe among the low temperature ammonia nitridation products under 5 T magnetic field at room temperature. The value changed not linearly against the yield as had been expected. Crystal structure refinement indicated that the phase similar to {alpha} Prime Prime -Fe{sub 16}N{sub 2} had deviations on its lattice constants and positional parameters, compared to previously reported values for {alpha} Prime Prime -Fe{sub 16}N{sub 2}. Spin-polarized total energy calculations were performed using the projector-augmented wave method as implemented in the Vienna ab-initio simulation package (VASP) to calculate magnetic moment on the refined crystal structure of the intermediate '{alpha} Prime Prime -Fe{sub 16}N{sub 2}'. The calculations supported the observed magnetization enhancement in the intermediate nitridation product. - Graphical abstract: Crystal structural parameters slightly change in the intermediate nitrided '{alpha} Prime Prime -Fe{sub 16}N{sub 2}' from those in {alpha} Prime Prime -Fe{sub 16}N{sub 2} to show the magnetization maxima in the mixture of '{alpha} Prime Prime -Fe{sub 16}N{sub 2}' and the residual {alpha}-F. Highlights: Black-Right-Pointing-Pointer Larger magnetization was observed than the value of Fe{sub 16}N{sub 2} on its intermediate nitrided mixture with residual {alpha}-Fe. Black-Right-Pointing-Pointer The enhancement was related to the crystal structural deviation from Fe{sub 16}N{sub 2} on the intermediate nitride. Black-Right-Pointing-Pointer It was supported by spin-polarized total energy calculation using the deviated structure.