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  1. September 2013 Most Viewed Documents for Biology And Medicine...

    Office of Scientific and Technical Information (OSTI)

    September 2013 Most Viewed Documents for Biology And Medicine Science Subject Feed Drug Retention Times Center for Human Reliability Studies (2007) 29 > Oleoresin Capsicum...

  2. March 2014 Most Viewed Documents for Biology And Medicine | OSTI...

    Office of Scientific and Technical Information (OSTI)

    March 2014 Most Viewed Documents for Biology And Medicine Science Subject Feed Carbon Dioxide Sequestering Using Microalgal Systems Daniel J. Stepan; Richard E. Shockey; Thomas A....

  3. January 2013 Most Viewed Documents for Power Generation And Distributi...

    Office of Scientific and Technical Information (OSTI)

    January 2013 Most Viewed Documents for Power Generation And Distribution Lessons from Large-Scale Renewable Energy Integration Studies: Preprint Bird, L.; Milligan, M. Small punch...

  4. March 2015 Most Viewed Documents for Biology And Medicine | OSTI...

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    March 2015 Most Viewed Documents for Biology And Medicine Measuring dopamine release in the human brain with PET Volkow, N.D. Brookhaven National Lab., Upton, NY (United...

  5. June 2014 Most Viewed Documents for Fission And Nuclear Technologies...

    Office of Scientific and Technical Information (OSTI)

    Viewed Documents for Fission And Nuclear Technologies Behavior of spent nuclear fuel in water pool storage Johnson, A.B. Jr. (1977) 78 Estimation of gas leak rates through very...

  6. January 2013 Most Viewed Documents for Mathematics And Computing...

    Office of Scientific and Technical Information (OSTI)

    Documents for Mathematics And Computing Cybersecurity through Real-Time Distributed Control Systems Kisner, Roger A ORNL; Manges, Wayne W ORNL; MacIntyre, Lawrence Paul...

  7. June 2014 Most Viewed Documents for Power Generation And Distribution...

    Office of Scientific and Technical Information (OSTI)

    Documents for Power Generation And Distribution Science Subject Feed Seventh Edition Fuel Cell Handbook NETL (2004) 118 > Electric power high-voltage transmission lines:...

  8. April 2013 Most Viewed Documents for Biology And Medicine | OSTI...

    Office of Scientific and Technical Information (OSTI)

    Delivery and Gene Transfection Daniela Rodica Radu (2005) 84 > Advisory Committee on human radiation experiments. Supplemental Volume 2a, Sources and documentation appendices....

  9. March 2015 Most Viewed Documents for Mathematics And Computing...

    Office of Scientific and Technical Information (OSTI)

    system solver Petzold, L.R. (1982) 98 Health and environmental effects document on geothermal energy: 1981 Layton, D.W.; Anspaugh, L.R.; O'Banion, K.D. (1981) 95 Comparison of...

  10. June 2015 Most Viewed Documents for Mathematics And Computing...

    Office of Scientific and Technical Information (OSTI)

    (1997) 53 PC-1D installation manual and user's guide Basore, P.A. (1991) 52 Conduction heat transfer solutions VanSant, J.H. (1983) 52 Health and environmental effects document...

  11. April 2013 Most Viewed Documents for Energy Storage, Conversion, And

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » Manhattanand

  12. April 2013 Most Viewed Documents for Fission And Nuclear Technologies |

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » ManhattanandOffice

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History »Dept of Energy,OSTI, US

  14. GROWTH OF GaN ON POROUS SiC SUBSTRATES BY PLASMA-ASSISTED MOLECULAR BEAM EPITAXY

    E-Print Network [OSTI]

    Feenstra, Randall

    1 GROWTH OF GaN ON POROUS SiC SUBSTRATES BY PLASMA-ASSISTED MOLECULAR BEAM EPITAXY C. K. Inoki ABSTRACT We have explored the growth of GaN on porous SiC substrates by plasma-assisted molecular beam Ga droplets. Plan-view TEM observations indicate that the GaN layers grown on porous substrates

  15. Document

    Energy Savers [EERE]

    5320 Federal Register Vol. 75, No. 204 Friday, October 22, 2010 Notices intervene or protest must serve a copy of that document on the Applicant. Notice is hereby given that...

  16. Document:

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

    position monitor (BPM) is on the order of a few milliseconds, the cooling effect due to remote water convection is limited. In addition, in view of the localized power input, it...

  17. Rhetoric, World-view, and Strategy in United States National Security Strategy Documents

    E-Print Network [OSTI]

    Cram, Travis J.

    2014-08-31T23:59:59.000Z

    to solve global problems and manage threats requires that these audiences buy-in to the presidents assessment of threats and possible solutions. Evaluating NSS documents as instances of symbolic action may enable critics to understand how NSS documents... the United States as the unwilling, virtuous victim in order to legitimize defense build-ups, explain policy failures, or warrant American military interventions abroad (Ivie, 1984; Klope, 1986). Reagans approach to nuclear weapons and missile defenses...

  18. document

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    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'sis Taking Over OurThe Iron4 Self-Scrubbing:,, , ., ..., ,+ .-detonation detectionDocument

  19. Documents

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    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 for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign:INEA : Papers69 Federal Register / Vol.PREDICTINGvN3Documents

  20. P2P Views Over Annotated Documents Konstantinos Karanasos, Ioana Manolescu

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    . Publication of such resources is inherently distributed. One could consider up- loading all published content] and social networks' tagging are among the most common methods to express annotations. Here, we designate and annotations. At the core of content sharing in AnnoVIP stand materialized views over the whole network content

  1. April 2013 Most Viewed Documents for Materials | OSTI, US Dept of Energy,

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History »

  2. April 2013 Most Viewed Documents for Biology And Medicine | OSTI, US Dept

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » Manhattanand Summer

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » Manhattanand SummerOffice

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » ManhattanandOffice of

  5. April 2013 Most Viewed Documents for Environmental Sciences | OSTI, US Dept

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » ManhattanandOffice ofof

  6. April 2013 Most Viewed Documents for Geosciences | OSTI, US Dept of Energy,

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History » ManhattanandOfficeOffice

  7. April 2013 Most Viewed Documents for Mathematics And Computing | OSTI, US

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History »Dept of Energy, Office of

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    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 for4,645U.S. DOE Office511041cloth DocumentationProductsAlternativeOperational Management » History »Dept of Energy,

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  11. GaN nanowires show more 3D piezoelectricity than bulk GaN

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Logo GaN nanowires show more 3D piezoelectricity than bulk GaN admin / January 11, 2012 individual gallium nitride (GaN) nanowires showing strong piezoelectric effect in 3D. This is in spite of the fact that each nanowire only measures 100nm in diameter. While GaN is ubiquitous in optoelectronic

  12. Invited Paper GaN HEMT reliability

    E-Print Network [OSTI]

    del Alamo, Jess A.

    Invited Paper GaN HEMT reliability J.A. del Alamo *, J. Joh Microsystems Technology Laboratories mechanism recently identified in GaN high-electron mobility transistors subject to electrical stress. Under high voltage, it has been found that electrically active defects are generated in the AlGaN barrier

  13. Nanoair-bridged lateral overgrowth of GaN on ordered nanoporous GaN template

    SciTech Connect (OSTI)

    Wang, Y.D.; Zang, K.Y.; Chua, S.J.; Tripathy, S.; Chen, P.; Fonstad, C.G. [Singapore-MIT Alliance, E4-04-10, 4 Engineering Drive 3, Singapore 117576 (Singapore) and Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Department of Electrical and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2005-12-19T23:59:59.000Z

    We report the growth of high-quality GaN epilayers on an ordered nanoporous GaN template by metalorganic chemical vapor deposition. The nanopores in GaN template were created by inductively coupled plasma etching using anodic aluminum oxide film as an etch mask. The average pore diameter and interpore distance is about 65 and 110 nm, respectively. Subsequent overgrowth of GaN first begins at the GaN crystallite surface between the pores, and then air-bridge-mediated lateral overgrowth leads to the formation of the continuous layer. Microphotoluminescence and micro-Raman measurements show improved optical properties and significant strain relaxation in the overgrown layer when compared to GaN layer of same thickness simultaneously grown on sapphire without any template. Similar to conventional epitaxial lateral overgrown GaN, such overgrown GaN on a nanopatterned surface would also serve as a template for the growth of ultraviolet-visible light-emitting III-nitride devices.

  14. Degradation mechanisms of GaN high electron mobility transistors

    E-Print Network [OSTI]

    Joh, Jungwoo

    2007-01-01T23:59:59.000Z

    In spite of their extraordinary performance, GaN high electron mobility transistors (HEMT) have still limited reliability. In RF power applications, GaN HEMTs operate at high voltage where good reliability is essential. ...

  15. GaN Nanopore Arrays: Fabrication and Characterization

    E-Print Network [OSTI]

    Wang, Yadong

    GaN nanopore arrays with pore diameters of approximately 75 nm were fabricated by inductively coupled plasma etching (ICP) using anodic aluminum oxide (AAO) films as etch masks. Nanoporous AAO films were formed on the GaN ...

  16. Rapid Communications Strong piezoelectricity in individual GaN nanowires

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Rapid Communications Strong piezoelectricity in individual GaN nanowires Majid Minary@northwestern.edu (Received 12 July 2011; accepted 15 September 2011) Abstract GaN nanowires are promising building blocks piezoelectricity in individual single-crystal GaN nanowires revealed by direct measurement of the piezoelectric

  17. GaN Radiation Detectors for Particle Physics and

    E-Print Network [OSTI]

    Glasgow, University of

    GaN Radiation Detectors for Particle Physics and Synchrotron Applications James Paul Grant and monitoring applications. Gallium nitride (GaN) was investigated as a radiation hard particle detector diameter on three epitaxial GaN wafers grown on a sapphire sub- strate. Two of the wafers were obtained

  18. Growth of GaN on porous SiC and GaN substrates C. K. Inoki1

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Growth of GaN on porous SiC and GaN substrates C. K. Inoki1 , T. S. Kuan1 , Ashutosh Sagar2 , C, Albuquerque, NM 87185 4 Beckman Institute, University of Illinois, Urbana, IL 61801 GaN films were grown on porous SiC and GaN templates using both plasma-assisted molecular beam epitaxy (PAMBE) and metal

  19. Better Buildings Network View | May 2014 | Department of Energy

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    May 2014 More Documents & Publications Better Buildings Network View | July-August 2014 Better Buildings Network View | June...

  20. Better Buildings Network View | November 2014 | Department of...

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

    November 2014 More Documents & Publications Better Buildings Network View | July-August 2014 Better Buildings Network View | December 2014 Better Buildings Network View | January...

  1. GaN based nanorods for solid state lighting

    SciTech Connect (OSTI)

    Li Shunfeng; Waag, Andreas [Institute of Semiconductor Technology, Braunschweig University of Technology, 38106 Braunschweig (Germany)

    2012-04-01T23:59:59.000Z

    In recent years, GaN nanorods are emerging as a very promising novel route toward devices for nano-optoelectronics and nano-photonics. In particular, core-shell light emitting devices are thought to be a breakthrough development in solid state lighting, nanorod based LEDs have many potential advantages as compared to their 2 D thin film counterparts. In this paper, we review the recent developments of GaN nanorod growth, characterization, and related device applications based on GaN nanorods. The initial work on GaN nanorod growth focused on catalyst-assisted and catalyst-free statistical growth. The growth condition and growth mechanisms were extensively investigated and discussed. Doping of GaN nanorods, especially p-doping, was found to significantly influence the morphology of GaN nanorods. The large surface of 3 D GaN nanorods induces new optical and electrical properties, which normally can be neglected in layered structures. Recently, more controlled selective area growth of GaN nanorods was realized using patterned substrates both by metalorganic chemical vapor deposition (MOCVD) and by molecular beam epitaxy (MBE). Advanced structures, for example, photonic crystals and DBRs are meanwhile integrated in GaN nanorod structures. Based on the work of growth and characterization of GaN nanorods, GaN nanoLEDs were reported by several groups with different growth and processing methods. Core/shell nanoLED structures were also demonstrated, which could be potentially useful for future high efficient LED structures. In this paper, we will discuss recent developments in GaN nanorod technology, focusing on the potential advantages, but also discussing problems and open questions, which may impose obstacles during the future development of a GaN nanorod based LED technology.

  2. Amorphization Processes in Au Ion Irradiated GaN at 150 - 300...

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

    Processes in Au Ion Irradiated GaN at 150 - 300 K. Amorphization Processes in Au Ion Irradiated GaN at 150 - 300 K. Abstract: Epitaxial single-crystal gallium nitride (GaN) films...

  3. Damage Evolution in GaN Under MeV Heavy Ion Implantation. | EMSL

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

    Evolution in GaN Under MeV Heavy Ion Implantation. Damage Evolution in GaN Under MeV Heavy Ion Implantation. Abstract: Damage evaluation processes in patterned GaN implanted by 3...

  4. Mapping misorientation and crystallographic tilt in GaN layers via polychromatic microdiffraction

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    coefficients between GaN and the substrate. Understandingpenetrate both the GaN layer and the substrate. Two samplespattern from the GaN layer and the substrate on a charge-

  5. GROWTH OF GaN ON POROUS SiC AND GaN SUBSTRATES C. K. Inoki and T. S. Kuan

    E-Print Network [OSTI]

    Feenstra, Randall

    1 GROWTH OF GaN ON POROUS SiC AND GaN SUBSTRATES C. K. Inoki and T. S. Kuan Department of Physics Institute, University of Illinois, Urbana, IL 61801 ABSTRACT We have studied the growth of GaN on porous SiC and GaN substrates, employing both plasma-assisted molecular beam epitaxy (PAMBE) and metalorganic

  6. The Co-Design of Scenarios for a Didactic-based E-learning System viewed as an Adaptive Virtual Document

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    The Co-Design of Scenarios for a Didactic-based E-learning System viewed as an Adaptive Virtual of the theory in didactic anthropology of knowledge and to show why we can formalize them in a hierarchical task scientific approaches ­ from computer science, didactic, cognitive psychology, education, etc. The design

  7. P-type doping of GaN

    SciTech Connect (OSTI)

    Wong, R.K.

    2000-04-10T23:59:59.000Z

    After implantation of As, As + Be, and As + Ga into GaN and annealing for short durations at temperatures as high as 1500 C, the GaN films remained highly resistive. It was apparent from c-RBS studies that although implantation damage did not create an amorphous layer in the GaN film, annealing at 1500 C did not provide enough energy to completely recover the radiation damage. Disorder recovered significantly after annealing at temperatures up to 1500 C, but not completely. From SIMS analysis, oxygen contamination in the AIN capping layer causes oxygen diffusion into the GaN film above 1400 C. The sapphire substrate (A1203) also decomposed and oxygen penetrated into the backside of the GaN layer above 1400 C. To prevent donor-like oxygen impurities from the capping layer and the substrate from contaminating the GaN film and compensating acceptors, post-implantation annealing should be done at temperatures below 1500 C. Oxygen in the cap could be reduced by growing the AIN cap on the GaN layer after the GaN growth run or by depositing the AIN layer in a ultra high vacuum (UHV) system post-growth to minimize residual oxygen and water contamination. With longer annealing times at 1400 C or at higher temperatures with a higher quality AIN, the implantation drainage may fully recover.

  8. Free excitons in wurtzite GaN A. V. Rodina*

    E-Print Network [OSTI]

    Nabben, Reinhard

    Free excitons in wurtzite GaN A. V. Rodina* I. Physics Institute, Justus Liebig University in wurtzite GaN. Using polarization-dependent measurements we were able to resolve the fine-structure energy these data a theory is developed for the exciton energy structure in hexagonal semiconductors with wurtzite

  9. New Faces of GaN: Growth, Doping and Devices

    E-Print Network [OSTI]

    California at Santa Barbara, University of

    New Faces of GaN: Growth, Doping and Devices James S. Speck Materials Department University of California Santa Barbara, CA LEO of a-GaN from circular opening Engineering Insights 2006 #12;#12;Personnel. Wraback (ARL) $$$ JST ERATO UCSB SSLDC AFOSR ONR #12;Reversed direction of polarization Bulk GaN

  10. Ga NMR spectra and relaxation in wurtzite GaN M. Corti and A. Gabetta

    E-Print Network [OSTI]

    Svane, Axel Torstein

    69,71 Ga NMR spectra and relaxation in wurtzite GaN M. Corti and A. Gabetta Department of Physics properties of wurtzite GaN are studied by Ga nuclear magnetic resonance NMR in a GaN bulk crystal containing GaN is a wide band-gap semiconductor which crystallizes in the hexagonal wurtzite structure

  11. Structural and electronic properties of Fe3+ in GaN from optical and EPR experiments

    E-Print Network [OSTI]

    Nabben, Reinhard

    into GaN to compensate inherent n-type conductivity and to produce semi-insulating substrate materialStructural and electronic properties of Fe3+ and Fe2+ centers in GaN from optical and EPR, and electronic properties of Fe-doped GaN. A set of high-quality GaN crystals doped with Fe at concentrations

  12. GaN: Defect and Device Issues

    SciTech Connect (OSTI)

    Pearton, S.J.; Ren, F.; Shul, R.J.; Zolper, J.C.

    1998-11-09T23:59:59.000Z

    The role of extended and point defects, and key impurities such as C, O and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

  13. ARM - AMIE Gan Island - Data Plots

    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: National5Sales for4,645U.S. DOE Office of ScienceandMesa del(ANL-IN-03-032)8Li (59AJ76) (See theDoctoral20ALSNewstt^APPLIANCETracerOverviewGan

  14. Optical spectroscopy of cubic GaN in nanowires

    SciTech Connect (OSTI)

    Renard, J. [CEA-CNRS Group 'Nanophysique et semiconducteurs', CEA-Grenoble INAC-SP2M, Institut Neel, CNRS, Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada); Tourbot, G. [CEA-CNRS Group 'Nanophysique et semiconducteurs', CEA-Grenoble INAC-SP2M, Institut Neel, CNRS, Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); CEA-LETI, MINATEC, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France); Sam-Giao, D.; Bougerol, C.; Daudin, B.; Gayral, B. [CEA-CNRS Group 'Nanophysique et semiconducteurs', CEA-Grenoble INAC-SP2M, Institut Neel, CNRS, Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2010-08-23T23:59:59.000Z

    We show that highly homogeneous cubic GaN can be grown by plasma-assisted molecular beam epitaxy on wurtzite GaN nanowires. The line width of the donor bound exciton is below 3 meV and can reach 1.6 meV in the best parts of the studied sample. This allows to perform a detailed spectroscopy of cubic GaN, and, in particular, to determine the precise spectral positions of the donor bound exciton, the fundamental free exciton and the split-off exciton in a photoluminescence experiment.

  15. Better Buildings Network View | April 2014 | Department of Energy

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

    April 2014 More Documents & Publications Better Buildings Network View | December 2014 Better Buildings Residential Network Orientation Better Buildings Network View | November...

  16. Better Buildings Network View | January 2015 | Department of...

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

    5 More Documents & Publications Better Buildings Network View | December 2014 Better Buildings Network View | November 2014 Better Buildings Residential Network Orientation...

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  18. Design, characterization, and modeling of GaN based HFETs for millimeter wave and microwave power amplifier applications

    E-Print Network [OSTI]

    Conway, Adam M.

    2006-01-01T23:59:59.000Z

    power GaN electronics thermally resistive substrates, IEEE400um SiC (Si, GaN, Sapphire, Diamond) substrate 5um Au 50umfree standing GaN or SiC substrates). At room temperature,

  19. TEM-Untersuchungen an GaN basierten Halbleiterheterostrukturen fur

    E-Print Network [OSTI]

    Schubart, Christoph

    TEM-Untersuchungen an GaN basierten Halbleiterheterostrukturen fur optoelektronische Anwendungen . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 5.1.2 Versetzungen bei Homoapitaxie auf GaN-Substraten . . . . 79 5.2 Versetzungsreduktion durch

  20. Micro Raman Spectroscopy of Annealed Erbium Implanted GaN

    E-Print Network [OSTI]

    Vajpeyi, Agam P.

    Wurtzite GaN epilayers grown by metal organic chemical vapor deposition on sapphire substrates were subsequently ion implanted with Er to a dose of 510? cm?. The implanted samples were annealed in nitrogen atmosphere ...

  1. Ion-beam-induced chemical disorder in GaN

    SciTech Connect (OSTI)

    Ishimaru, Manabu; Zhang, Yanwen; Weber, William J.

    2009-09-08T23:59:59.000Z

    Atomistic structures of high-energy ion irradiated GaN have been examined using transmission electron microscopy (TEM). Single crystalline GaN substrates were irradiated at cryogenic temperature with 2 MeV Au2+ ions to a fluence of 7.35x1015 Au/cm2. Cross-sectional TEM observations revealed that damaged layers consisting of amorphous and nanocrystalline phases are formed at the surface and buried depth of the as-irradiated GaN substrate. Atomic radial distribution functions of the amorphous/poly-nanocrystalline regions showed that not only heteronuclear Ga-N bonds but also homonuclear Ga-Ga bonds exist within the first coordination shell. It was found that the ratio of heteronuclear-to-homonuclear bonds, i.e., the degree of chemical disorder is different between the surface and buried damaged layers. The alternation of chemical disorder was attributed to the difference in the defect formation processes between these layers.

  2. ARM MJO Investigation Experiment on Gan Island (AMIE-Gan) Science Plan

    SciTech Connect (OSTI)

    Long, CL; Del Genio, A; Deng, M; Fu, X; Gustafson, W; Houze, R; Jakob, C; Jensen, M; Johnson, R; Liu, X; Luke, E; May, P; McFarlane, S; Minnis, P; Schumacher, C; Vogelmann, A; Wang, Y; Webster, P; Xie, S; Zhang, C

    2011-04-11T23:59:59.000Z

    The overarching campaign, which includes the ARM Mobile Facility 2 (AMF2) deployment in conjunction with the Dynamics of the Madden-Julian Oscillation (DYNAMO) and the Cooperative Indian Ocean experiment on intraseasonal variability in the Year 2011 (CINDY2011) campaigns, is designed to test several current hypotheses regarding the mechanisms responsible for Madden-Julian Oscillation (MJO) initiation and propagation in the Indian Ocean area. The synergy between the proposed AMF2 deployment with DYNAMO/CINDY2011, and the corresponding funded experiment on Manus, combine for an overarching ARM MJO Investigation Experiment (AMIE) with two components: AMF2 on Gan Island in the Indian Ocean (AMIE-Gan), where the MJO initiates and starts its eastward propagation; and the ARM Manus site (AMIE-Manus), which is in the general area where the MJO usually starts to weaken in climate models. AMIE-Gan will provide measurements of particular interest to Atmospheric System Research (ASR) researchers relevant to improving the representation of MJO initiation in climate models. The framework of DYNAMO/CINDY2011 includes two proposed island-based sites and two ship-based locations forming a square pattern with sonde profiles and scanning precipitation and cloud radars at both island and ship sites. These data will be used to produce a Variational Analysis data set coinciding with the one produced for AMIE-Manus. The synergy between AMIE-Manus and AMIE-Gan will allow studies of the initiation, propagation, and evolution of the convective cloud population within the framework of the MJO. As with AMIE-Manus, AMIE-Gan/DYNAMO also includes a significant modeling component geared toward improving the representation of MJO initiation and propagation in climate and forecast models. This campaign involves the deployment of the second, marine-capable, AMF; all of the included measurement systems; and especially the scanning and vertically pointing radars. The campaign will include sonde launches at a rate of eight per day for the duration of the deployment. The increased sonde launches for the entire period matches that of the AMIE-Manus campaign and makes possible a far more robust Variational Analysis forcing data set product for the entire campaign, and thus better capabilities for modeling studies and synergistic research using the data from both AMIE sites.

  3. Thermal evolution of microstructure in ion-irradiated GaN. |...

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

    evolution of microstructure in ion-irradiated GaN. Thermal evolution of microstructure in ion-irradiated GaN. Abstract: The thermal evolution of the microstructure created by...

  4. High Density Single Crystalline GaN Nanodot Arrays Fabricated Using Template-Assisted Selective Growth

    E-Print Network [OSTI]

    Wang, Yadong

    High density, uniform GaN nanodot arrays with controllable size have been synthesized by using template-assisted selective growth. The GaN nanodots with average diameter 40nm, 80nm and 120nm were selectively grown by ...

  5. Damage and Microstructure Evolution in GaN under Au Ion Irradiation...

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

    and Microstructure Evolution in GaN under Au Ion Irradiation. Damage and Microstructure Evolution in GaN under Au Ion Irradiation. Abstract: Damage and microstructure evolution in...

  6. Structural Defects in Laterally Overgrown GaN Layers Grown on Non-polar Substrates

    E-Print Network [OSTI]

    Liliental-Weber, Z.; Ni, X.; Morkoc, H.

    2007-01-01T23:59:59.000Z

    Overgrown GaN Layers Grown on Non-polar Substrates Z.in GaN layers grown on polar and non-polar substrates areGaN-based layers, since they are grown heteroepitaxially on foreign substrates (

  7. Raman scattering from defects in GaN: The question of vibrational or electronic scattering mechanism

    E-Print Network [OSTI]

    Nabben, Reinhard

    Raman scattering from defects in GaN: The question of vibrational or electronic scattering on defects in GaN, which appear in the Raman spectra as sharp and intense lines in the low-energy region from into the GaN material. S0163-1829 98 00344-0 I. INTRODUCTION Low-temperature Raman spectra of GaN films grown

  8. Zeeman spectroscopy of the Fe3 center in GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    vapor deposition grown GaN Ronny Kirste, Ramn Collazo, Gordon Callsen, Markus R. Wagner, Thomas Kure et vapor deposition grown GaN Ronny Kirste,1,a) Ramon Collazo,2 Gordon Callsen,1 Markus R. Wagner,1 Thomas in GaN. GaN with Ga- to N-polar junctions was grown on sapphire using an AlN buffer layer. Results from

  9. Piezoelectric polarization associated with dislocations in wurtzite GaN Changchun Shi,a)

    E-Print Network [OSTI]

    Yu, Edward T.

    Piezoelectric polarization associated with dislocations in wurtzite GaN Changchun Shi,a) Peter M axis in wurtzite GaN. It is shown that the polarization field generated by screw components with the c-axis oriented dislocations in wurtzite GaN, and de- scribe the piezoelectric polarization

  10. Determination of wurtzite GaN lattice polarity based on surface reconstruction

    E-Print Network [OSTI]

    Determination of wurtzite GaN lattice polarity based on surface reconstruction A. R. Smith and R. M identify two categories of reconstructions occurring on wurtzite GaN surfaces, the first associated nitride-based devices, epi- taxial growth occurs on the c plane of wurtzite GaN. A key characteristic

  11. Wurtzite GaN Surface Structures Studied by Scanning Tunneling Microscopy and Reflection High Energy

    E-Print Network [OSTI]

    Feenstra, Randall

    Wurtzite GaN Surface Structures Studied by Scanning Tunneling Microscopy and Reflection High Energy studies of the surface reconstructions for both the Ga-face and the N-face of wurtzite GaN films grown a surface phenomenon. Although numerous surface studies of wurtzite GaN have been performed, progress

  12. Inversion of wurtzite GaN(0001) by exposure to V. Ramachandran and R. M. Feenstra

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Inversion of wurtzite GaN(0001) by exposure to magnesium V. Ramachandran and R. M. Feenstra 15213 Abstract Magnesium incorporation during the molecular beam epitaxy growth of wurtzite GaN is found important. Most devices are built on the polar basal plane of wurtzite GaN, and the characteristics

  13. Ab initio prediction of GaN ,,1010... and ,,110... anomalous surface relaxation John E. Jaffe

    E-Print Network [OSTI]

    Pandey, Ravi

    Ab initio prediction of GaN ,,1010... and ,,110... anomalous surface relaxation John E. Jaffe Received 22 September 1995 The results of a study of the surface relaxation of GaN in the framework is minimized the Ga-N surface bonds show a very small rotation angle of about 6 accompanied by a reduction

  14. Temperature and pressure dependence of Mg local modes in GaN G. Kaczmarczyk,a)

    E-Print Network [OSTI]

    Nabben, Reinhard

    Temperature and pressure dependence of Mg local modes in GaN G. Kaczmarczyk,a) A. Kaschner, A in the hexagonal modification of GaN was studied within a valence-force model. The contribution caused by thermal the shift of the GaN host modes. 2001 American Institute of Physics. DOI: 10.1063/1.1339848 Doped III

  15. Stress analysis of selective epitaxial growth of GaN Q. K. K. Liua)

    E-Print Network [OSTI]

    Nabben, Reinhard

    Stress analysis of selective epitaxial growth of GaN Q. K. K. Liua) Bereich Theoretische Physik Stress distributions in selectively overgrown self-organized GaN hexagonal pyramids have been analyzed in the literature and an effective lattice mismatch between the GaN and the substrate that was determined from

  16. Band gap changes of GaN shocked to 13 GPa M. D. McCluskeya)

    E-Print Network [OSTI]

    McCluskey, Matthew

    Band gap changes of GaN shocked to 13 GPa M. D. McCluskeya) and Y. M. Gupta Institute for Shock, California 94304 Received 24 October 2001; accepted for publication 19 December 2001 The band gap of GaN in shock-wave experiments. Shock waves were generated by impacting the GaN samples with c-cut sapphire

  17. Indium-induced changes in GaN,,0001... surface morphology John E. Northrup

    E-Print Network [OSTI]

    Indium-induced changes in GaN,,0001... surface morphology John E. Northrup Xerox Palo Alto Research-principles calculations of the energetics of the In-terminated GaN 0001 , (0001), (1011), and (1011) surfaces indicate- retical studies to determine the behavior of In on GaN sur- faces. The term surfactant is used often

  18. Large atomic displacements associated with the nitrogen antisite in GaN T. Mattila*

    E-Print Network [OSTI]

    Large atomic displacements associated with the nitrogen antisite in GaN T. Mattila* Laboratory of an extensive theoretical study of the nitrogen antisite in GaN. The neutral antisite in c-GaN is reported the nitrogen antisite and the yellow luminescence commonly observed in GaN is discussed. S0163-1829 96 05824

  19. LA TECHNOLOGIE GAN ET SES APPLICATIONS POUR L'ELECTRONIQUE ROBUSTE, HAUTE FREQUENCE ET DE

    E-Print Network [OSTI]

    Boyer, Edmond

    technologies carbure de silicium (SiC) et nitrure de gallium (GaN) possdent des qualits intrinsques ralisation de dispositifs optiques (GaN et alliages InP, Al, P), ce qui autorise un spectre d'applications du visible aux ultraviolets, en mission et en dtection : le matriau GaN est le seul qui puisse prtendre

  20. Photoconduction studies on GaN nanowire transistors under UV and polarized UV illumination

    E-Print Network [OSTI]

    Zhou, Chongwu

    Photoconduction studies on GaN nanowire transistors under UV and polarized UV illumination Song Han carried out with single crystal GaN nanowires. The nanowire transistors exhibited a sub- stantial increase was demonstrated and studied for GaN nanowires working as polarized UV detectors. The nanowire conductance varied

  1. Porous GaN nanowires synthesized using thermal chemical vapor deposition

    E-Print Network [OSTI]

    Kim, Bongsoo

    Porous GaN nanowires synthesized using thermal chemical vapor deposition Seung Yong Bae a , Hee Won 2003 Abstract Porous structured GaN nanowires were synthesized with a large scale by chemical vapor to 1 mm. The porous GaN nanowires consist of the wurtzite single crystal grown with the [0 1 1

  2. Properties of GaN and ZnO Quantum Dots

    E-Print Network [OSTI]

    CHAPTER 3 Properties of GaN and ZnO Quantum Dots Vladimir A. Fonoberov, Alexander A. Balandin Nano. GaN Quantum Dots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 2.1. Electron and Hole States in Strained Wurtzite and Zincblende GaN Quantum Dots

  3. 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

  4. Watching GaN Nanowires Grow Eric A. Stach,*, Peter J. Pauzauskie, Tevye Kuykendall,

    E-Print Network [OSTI]

    Yang, Peidong

    Watching GaN Nanowires Grow Eric A. Stach,*, Peter J. Pauzauskie, Tevye Kuykendall, Joshua of the growth of GaN nanowires via a self-catalytic vapor-liquid-solid (VLS) mechanism. High temperature thermal decomposition of GaN in a vacuum yields nanoscale Ga liquid droplets and gallium/nitrogen vapor species

  5. A conductivity-based selective etching for next generation GaN devices

    E-Print Network [OSTI]

    Cao, Hui

    A conductivity-based selective etching for next generation GaN devices Yu Zhang 1 , Sang-Wan Ryu 2 etching having large selectivity based on the conductivity of n-type GaN was investigated to demonstrate on the doping concentration and applied voltage. For photonic applications, GaN microdisks and distributed Bragg

  6. Growth of GaN Thin Films on Silicon Using Single Source Precursors

    E-Print Network [OSTI]

    Boo, Jin-Hyo

    Growth of GaN Thin Films on Silicon Using Single Source Precursors and Development of New We have grown the GaN thin films on silicon substrates using the newly developed single source precursors by thermal MOCVD method. Highly oriented GaN thin films in the [002] direction with hexagonal

  7. Control of growth orientation of GaN nanowires H.Y. Peng, N. Wang 1

    E-Print Network [OSTI]

    Zheng, Yufeng

    -dependent growth directions. At a substrate temperature of 900950 C, the growth direction of GaN nanowires, it has become possible to grow single crystal films of GaN on various substrates by metalControl of growth orientation of GaN nanowires H.Y. Peng, N. Wang 1 , X.T. Zhou, Y.F. Zheng, C

  8. Microstructures of GaN films deposited on (001) and (111) Si substrates using electron

    E-Print Network [OSTI]

    Basu, Soumendra N.

    Microstructures of GaN films deposited on (001) and (111) Si substrates using electron cyclotron 1993; accepted 26 April 1994) The microstructures of GaN films, grown on (001) and (111) Si substrates-blende structure. The GaN buffer layer, grown in the first deposition step, accommodated the 17% lattice mismatch

  9. In situ growth regime characterization of cubic GaN using reflection high energy electron diffraction

    E-Print Network [OSTI]

    As, Donat Josef

    from Knudsen cells. Cubic GaN layers were deposited at 720 C directly on 3C-SiC substrates shutters the GaN surface was exposed to different Ga fluxes for a certain time. The substrate temperatureIn situ growth regime characterization of cubic GaN using reflection high energy electron

  10. Strain dependent facet stabilization in selective-area heteroepitaxial growth of GaN nanostructures

    E-Print Network [OSTI]

    Sharma, Pradeep

    of submicron GaN islands on GaN-sapphire, AlN-sapphire, and bare sapphire substrates. It is shown that strain due to the lattice mismatch between GaN and the underlying substrate has a significant influence- structures has received less attention. Heteroepitaxial growth of GaN is commonly carried out on substrates

  11. Vertical strain and doping gradients in thick GaN layers H. Siegle,a)

    E-Print Network [OSTI]

    Nabben, Reinhard

    between layer and common substrates, e.g., sapphire or GaAs.1 Consequently, most GaN layers and also from the surface of the GaN layer nearer to the substrate interface, as can be seen from the CLVertical strain and doping gradients in thick GaN layers H. Siegle,a) A. Hoffmann, L. Eckey, and C

  12. Growth of GaN on porous SiC by molecular beam epitaxy

    E-Print Network [OSTI]

    Feenstra, Randall

    growth of high quality GaN thin films is the unavailability suitable substrates. The lack of suitable matched between the GaN and the substrate are the lattice parameter and the coefficient of thermal to the absence of high quality, large area GaN substrates. Therefore one has to resort to the heteroepitaxial

  13. TEM studies of laterally overgrown GaN layers grown on non-polar substrates

    E-Print Network [OSTI]

    Liliental-Weber, Z.; Ni, X.; Morkoc, H.

    2006-01-01T23:59:59.000Z

    between these substrates and the GaN layers leads to a highpendeo-epitaxial GaN layer grown on (1120) 4H-SiC substrate.in GaN layers grown on polar and non-polar substrates are

  14. Anti-phase domains in cubic GaN

    SciTech Connect (OSTI)

    Maria Kemper, Ricarda; Schupp, Thorsten; Haeberlen, Maik; Lindner, Joerg; Josef As, Donat [University of Paderborn, Department of Physics, Warburger Str. 100, D-33098 Paderborn (Germany); Niendorf, Thomas; Maier, Hans-Juergen [University of Paderborn, Lehrstuhl fuer Werkstoffkunde, Pohlweg 47-49, D-33098 Paderborn (Germany); Dempewolf, Anja; Bertram, Frank; Christen, Juergen [University of Magdeburg, Institut fuer Festkoerperphysik, P.O. Box 4120, D-39016 Magdeburg (Germany); Kirste, Ronny; Hoffmann, Axel [Technische Universitaet Berlin, Institute of Solid State Physics, Hardenbergstr. 36, D-10623 Berlin (Germany)

    2011-12-15T23:59:59.000Z

    The existence of anti-phase domains in cubic GaN grown on 3C-SiC/Si (001) substrates by plasma-assisted molecular beam epitaxy is reported. The influence of the 3C-SiC/Si (001) substrate morphology is studied with emphasis on the anti-phase domains (APDs). The GaN nucleation is governed by the APDs of the substrate, resulting in equal plane orientation and the same anti-phase boundaries. The presence of the APDs is independent of the GaN layer thickness. Atomic force microscopy surface analysis indicates lateral growth anisotropy of GaN facets in dependence of the APD orientation. This anisotropy can be linked to Ga and N face types of the {l_brace}111{r_brace} planes, similar to observations of anisotropic growth in 3C-SiC. In contrast to 3C-SiC, however, a difference in GaN phase composition for the two types of APDs can be measured by electron backscatter diffraction, {mu}-Raman and cathodoluminescence spectroscopy.

  15. Abstract--A high performance GaN HFET WCDMA basestation power amplifier is presented, which uses an envelope

    E-Print Network [OSTI]

    Asbeck, Peter M.

    Abstract--A high performance GaN HFET WCDMA basestation power amplifier is presented, which uses, digital predistortion, WCDMA, GaN HFET. I. INTRODUCTION High power-added efficiency is an important] and FETs[3], and GaN HFETs[4][5] has been carried out. GaN HFETs are attractive options since they can

  16. Scanning Tunneling Microscopy Study of Cr-doped GaN Surface Grown by RF Plasma Molecular Beam Epitaxy

    E-Print Network [OSTI]

    doped MOCVD grown GaN on sapphire substrate [2]. Park et al. performed the growth of Cr doped GaN singleScanning Tunneling Microscopy Study of Cr-doped GaN Surface Grown by RF Plasma Molecular Beam Orleans, New Orleans, LA 70148, USA Abstract: Cr doped GaN was grown by rf N-plasma molecular beam epitaxy

  17. Revised: 12.23.2013 Bb 9(SP13): Customizing the Instructor's View of the Grade Center p. 1 of 7 This document covers features in the Grade Center that helps an instructor to manage the grade

    E-Print Network [OSTI]

    Qiu, Weigang

    This document covers features in the Grade Center that helps an instructor to manage the grade columns Center documents for more information about managing the Grade Center. Renaming Columns You can change in the Grade Center table. The document includes the following topics: Renaming Columns Rearranging Columns

  18. Redistribution of Implanted Dopants in GaN

    SciTech Connect (OSTI)

    Fu, M.; Gao, X.A.; Han, J.; Pearton, S.J.; Rieger, D.J.; Scarvepalli, V. Sekhar, J.A.; Shul, R.J.; Singh, R.K.; Wilson, R.G.; Zavada, J.M.; Zolper, J.C.

    1998-11-20T23:59:59.000Z

    Donor (S, Se and Te) and acceptor (Mg, Be and C) dopants have been implanted into GaN at doses of 3-5x1014 cm-2 and annealed at temperatures up to 1450 *C. No redistribution of any of the elements is detectable by Secondary Ion Mass Spectrometry, except for Be, which displays an apparent damage-assisted diffusion at 900 "C. At higher temperatures there is no further movement of the Be, suggesting that the point defect flux that assists motion at lower temperatures has been annealed. Effective diffusivities are <2X 1013 cm2.sec-1 at 1450 `C for each of the dopants in GaN.

  19. Evidence of N substitution by Mn in GaN

    E-Print Network [OSTI]

    Pereira, LMC; Decoster, S; Correia, JG; da Silva, MR; Vantomme, A; Arajo, JP

    2012-01-01T23:59:59.000Z

    We report on the lattice location of Mn in wurtzite GaN using beta? emission channeling. In addition to the majority substituting for Ga, we locate up to 20% of the Mn atoms in N sites. We propose that the incorporation of Mn in N sites is enabled under sufficiently high concentrations of N vacancies, and stabilized by a highly charged state of the Mn cations. Since N substitution by Mn impurities in wurtzite GaN has never been observed experimentally or even considered theoretically before, it challenges the current paradigm of transition metal incorporation in wide-gap dilute magnetic semiconductors.

  20. Ferromagnetism in undoped One-dimensional GaN Nanowires

    SciTech Connect (OSTI)

    Jeganathan, K., E-mail: kjeganathan@yahoo.com, E-mail: jagan@physics.bdu.ac.in; Purushothaman, V. [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India)] [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India); Debnath, R. [Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4 (Canada)] [Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4 (Canada); Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620 024 (India)] [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620 024 (India)

    2014-05-15T23:59:59.000Z

    We report an intrinsic ferromagnetism in vertical aligned GaN nanowires (NW) fabricated by molecular beam epitaxy without any external catalyst. The magnetization saturates at ?0.75 emu/gm with the applied field of 3000 Oe for the NWs grown under the low-Gallium flux of 2.4 10{sup ?8} mbar. Despite a drop in saturation magnetization, narrow hysteresis loop remains intact regardless of Gallium flux. Magnetization in vertical standing GaN NWs is consistent with the spectral analysis of low-temperature photoluminescence pertaining to Ga-vacancies associated structural defects at the nanoscale.

  1. GaN for x-ray detection

    SciTech Connect (OSTI)

    Duboz, Jean-Yves; Lauegt, Marguerite; Schenk, David [CRHEA, CNRS, rue Bernard Gregory, Sophia Antipolis, F-06560 Valbonne (France); Beaumont, Bernard [Lumilog, 2720 chemin de saint Bernard, F-06220 Vallauris (France); Reverchon, Jean-Luc [THALES R and T, route departementale 128, F-91767 Palaiseau Cedex (France); Wieck, Andreas D.; Zimmerling, Tino [Fakultaet fuer Physik und Astronomie, D-44780 Bochum (Germany)

    2008-06-30T23:59:59.000Z

    The potential of GaN based materials for x-ray detection is investigated. The absorption coefficient in GaN is measured as a function of photon energy between 6 and 40 keV. Metal-semiconductor-metal photodetectors are fabricated and characterized. The response dependence on bias, the temporal dynamics, and the response dependence on detector geometry all together point toward a mixing of photovoltaic and photoconductive effects. Thanks to a large photoconductive gain, the detector has a decent responsivity at the expense of a large response time.

  2. Properties of H, O and C in GaN

    SciTech Connect (OSTI)

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

    1996-04-01T23:59:59.000Z

    The electrical properties of the light ion impurities H, O and C in GaN have been examined in both as-grown and implanted material. H is found to efficiently passivate acceptors such as Mg, Ca and C. Reactivation occurs at {ge} 450 C and is enhanced by minority carrier injection. The hydrogen does not leave the GaN crystal until > 800 C, and its diffusivity is relatively high ({approximately} 10{sup {minus}11} cm{sup 2}/s) even at low temperatures (< 200 C) during injection by wet etching, boiling in water or plasma exposure. Oxygen shows a low donor activation efficiency when implanted into GaN, with an ionization level of 30--40 meV. It is essentially immobile up to 1,100 C. Carbon can produce low p-type levels (3 {times} 10{sup 17} cm{sup {minus}3}) in GaN during MOMBE, although there is some evidence it may also create n-type conduction in other nitrides.

  3. Refractive index of erbium doped GaN thin films

    SciTech Connect (OSTI)

    Alajlouni, S.; Sun, Z. Y.; 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); Zavada, J. M. [Department of Electrical and Computer Engineering, Polytechnic Institute of New York University, Brooklyn, New York 11201 (United States)

    2014-08-25T23:59:59.000Z

    GaN is an excellent host for erbium (Er) to provide optical emission in the technologically important as well as eye-safe 1540?nm wavelength window. Er doped GaN (GaN:Er) epilayers were synthesized on c-plane sapphire substrates using metal organic chemical vapor deposition. By employing a pulsed growth scheme, the crystalline quality of GaN:Er epilayers was significantly improved over those obtained by conventional growth method of continuous flow of reaction precursors. X-ray diffraction rocking curve linewidths of less than 300?arc sec were achieved for the GaN (0002) diffraction peak, which is comparable to the typical results of undoped high quality GaN epilayers and represents a major improvement over previously reported results for GaN:Er. Spectroscopic ellipsometry was used to determine the refractive index of the GaN:Er epilayers in the 1540?nm wavelength window and a linear dependence on Er concentration was found. The observed refractive index increase with Er incorporation and the improved crystalline quality of the GaN:Er epilayers indicate that low loss GaN:Er optical waveguiding structures are feasible.

  4. Luminescence properties of defects in GaN

    SciTech Connect (OSTI)

    Reshchikov, Michael A.; Morkoc, Hadis [Department of Electrical Engineering and Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)

    2005-03-15T23:59:59.000Z

    Gallium nitride (GaN) and its allied binaries InN and AIN as well as their ternary compounds have gained an unprecedented attention due to their wide-ranging applications encompassing green, blue, violet, and ultraviolet (UV) emitters and detectors (in photon ranges inaccessible by other semiconductors) and high-power amplifiers. However, even the best of the three binaries, GaN, contains many structural and point defects caused to a large extent by lattice and stacking mismatch with substrates. These defects notably affect the electrical and optical properties of the host material and can seriously degrade the performance and reliability of devices made based on these nitride semiconductors. Even though GaN broke the long-standing paradigm that high density of dislocations precludes acceptable device performance, point defects have taken the center stage as they exacerbate efforts to increase the efficiency of emitters, increase laser operation lifetime, and lead to anomalies in electronic devices. The point defects include native isolated defects (vacancies, interstitial, and antisites), intentional or unintentional impurities, as well as complexes involving different combinations of the isolated defects. Further improvements in device performance and longevity hinge on an in-depth understanding of point defects and their reduction. In this review a comprehensive and critical analysis of point defects in GaN, particularly their manifestation in luminescence, is presented. In addition to a comprehensive analysis of native point defects, the signatures of intentionally and unintentionally introduced impurities are addressed. The review discusses in detail the characteristics and the origin of the major luminescence bands including the ultraviolet, blue, green, yellow, and red bands in undoped GaN. The effects of important group-II impurities, such as Zn and Mg on the photoluminescence of GaN, are treated in detail. Similarly, but to a lesser extent, the effects of other impurities, such as C, Si, H, O, Be, Mn, Cd, etc., on the luminescence properties of GaN are also reviewed. Further, atypical luminescence lines which are tentatively attributed to the surface and structural defects are discussed. The effect of surfaces and surface preparation, particularly wet and dry etching, exposure to UV light in vacuum or controlled gas ambient, annealing, and ion implantation on the characteristics of the defect-related emissions is described.

  5. Ga adsorbate on (0001) GaN: In situ characterization with quadrupole mass spectrometry and reflection high-energy electron diffraction

    E-Print Network [OSTI]

    Brown, J S; Koblmuller, G; Wu, F; Averbeck, R; Riechert, H; Speck, J S

    2006-01-01T23:59:59.000Z

    PA-MBE GaN growth conditions, with substrate temperatures ofthe GaN surface roughness evolution, substrate vicinality,vapor and substrate temperature could form the basis for GaN

  6. In situ characterization of GaN quantum dot growth with reflection high-energy electron diffraction and line-of-sight mass spectrometry

    E-Print Network [OSTI]

    Brown, J S; Koblmuller, G; Averbeck, R; Riechert, H; Speck, J S

    2006-01-01T23:59:59.000Z

    PA-MBE GaN growth conditions, with substrate temperatures ofthe GaN surface roughness evolution, substrate vicinality,vapor and substrate temperature could form the basis for GaN

  7. Fabrication and Characterization of Nano-porous GaN Template for Strain Relaxed GaN Growth

    E-Print Network [OSTI]

    Hartono, Haryono

    A simple and cost-effective Si-doped porous GaN is fabricated by UV-enhanced electrochemical etching. An optimum current density of 20 mA/cm applied for an hour in dilute NaOH solution produces a high density of uniform ...

  8. Growth and characterization of horizontal GaN wires on silicon

    SciTech Connect (OSTI)

    Zou, Xinbo; May Lau, Kei, E-mail: eekmlau@ust.hk [Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Kowloon (Hong Kong); HKUST Jockey Club Institute for Advanced Study, The Hong Kong University of Science and Technology, Kowloon (Hong Kong); Lu, Xing [Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Kowloon (Hong Kong); Lucas, Ryan [Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Kuech, Thomas F. [HKUST Jockey Club Institute for Advanced Study, The Hong Kong University of Science and Technology, Kowloon (Hong Kong); Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Choi, Jonathan W.; Gopalan, Padma [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2014-06-30T23:59:59.000Z

    We report the growth of in-plane GaN wires on silicon by metalorganic chemical vapor deposition. Triangular-shaped GaN microwires with semi-polar sidewalls are observed to grow on top of a GaN/Si template patterned with nano-porous SiO{sub 2}. With a length-to-thickness ratio ?200, the GaN wires are well aligned along the three equivalent ? 112{sup }0 ? directions. Micro-Raman measurements indicate negligible stress and a low defect density inside the wires. Stacking faults were found to be the only defect type in the GaN wire by cross-sectional transmission electron microscopy. The GaN wires exhibited high conductivity, and the resistivity was 2030 m? cm, regardless of the wire thickness. With proper heterostructure and doping design, these highly aligned GaN wires are promising for photonic and electronic applications monolithically integrated on silicon.

  9. Computational synthesis of single-layer GaN on refractory materials

    SciTech Connect (OSTI)

    Singh, Arunima K.; Hennig, Richard G., E-mail: rhennig@cornell.edu [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2014-08-04T23:59:59.000Z

    The synthesis of single-layer materials relies on suitable substrates. In this paper, we identify suitable substrates for the stabilization and growth of single-layer GaN and characterize the effect of the substrate on the electronic structure of single-layer GaN. We identify two classes of epitaxial substrates, refractory metal diborides and transition-metal dichalcogenides. We find that the refractory diborides provide epitaxial stabilization for the growth and functionalization of single layer GaN. We show that chemical interactions of single layer GaN with the diboride substrates result in n-type doping of the single-layer GaN. Transition-metal dichalcogenides, on the other hand, although epitaxially matched, cannot provide sufficient thermodynamic stabilization for the growth of single layer GaN. Nonetheless, energy band alignments of GaN/metal chalcogenides show that they make good candidates for heterostructures.

  10. INCOMING DOCUMENT CONTROL FORM DOCUMENT DESCRIPTION ORGANIZATIO

    Office of Legacy Management (LM)

    INCOMING DOCUMENT CONTROL FORM DOCUMENT DESCRIPTION ORGANIZATIO )ATE COMPLETED: ACTION NUMBER: I I I DOCUMENT CONTROL DATE INITIALS DATA BASE: ACTION LOG: FILED: To : Doug...

  11. Determination of Wurtzite GaN Lattice Polarity Based on Surface Reconstruction

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Determination of Wurtzite GaN Lattice Polarity Based on Surface Reconstruction A. R. Smith,1 R. M of reconstructions occurring on wurtzite GaN surfaces, the first associated with the N-face, (000 ), and the secondN. In the fabrication of most nitride-based devices, epitaxial growth occurs on the c-plane of wurtzite GaN. A key

  12. Cubic GaN on Nanopatterned 3C-SiC/Si (001) Substrates

    E-Print Network [OSTI]

    As, Donat Josef

    Chapter 15 Cubic GaN on Nanopatterned 3C-SiC/Si (001) Substrates Ricarda Maria Kemper, Donat Josef relaxed cubic GaN by plasma-assisted molecular beam epitaxy on prepat- terned 3C-SiC/Si (001) substrates) process. We analyze the influence of the substrate on the GaN growth and show that it is possible to grow

  13. GaN Nanowire Arrays for High-Output Nanogenerators Chi-Te Huang,,

    E-Print Network [OSTI]

    Wang, Zhong L.

    epitaxially grown on GaN/sapphire substrates. The GaN NW possesses a triangular cross section enclosed by (0001j), (21j1j2), and (2j112) planes, and the angle between the GaN NW and the substrate surface is 62 process. For the epitaxial growth of GaN NW arrays, the substrates play an important role in determining

  14. Structural defects in GaN revealed by Transmission Electron Microscopy

    SciTech Connect (OSTI)

    Liliental-Weber, Zuzanna

    2014-04-18T23:59:59.000Z

    This paper reviews the various types of structural defects observed by Transmission Electron Microscopy in GaN heteroepitaxial layers grown on foreign substrates and homoepitaxial layers grown on bulk GaN substrates. The structural perfection of these layers is compared to the platelet self-standing crystals grown by High Nitrogen Pressure Solution. Defects in undoped and Mg doped GaN are discussed. Some models explaining the formation of inversion domains in heavily Mg doped layers that are possible defects responsible for the difficulties of p-doping in GaN are also reviewed.

  15. More Documents

    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: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your1 SECTIONES2008-54174More Documents More Documents

  16. Creation Date: May 7, 2013 Version: 1 Edited by: SR Client Services ITS Managed Document

    E-Print Network [OSTI]

    Northern British Columbia, University of

    Creation Date: May 7, 2013 Version: 1 Edited by: SR Client Services ITS Managed Document VIEW Client Services ITS Managed Document VIEW CLIENT INSTALLATION - MAC Page 2 When prompted with the End Edited by: SR Client Services ITS Managed Document VIEW CLIENT INSTALLATION - MAC Page 3 In Launchpad

  17. Creation Date: Feb 2014 Version: 1 Edited by: LB Application Services ITS Managed Document

    E-Print Network [OSTI]

    Northern British Columbia, University of

    Creation Date: Feb 2014 Version: 1 Edited by: LB Application Services ITS Managed Document VIEW: LB Application Services ITS Managed Document VIEW CLIENT INSTALLATION - MICROSOFT FEB 2014 STUDENT Managed Document VIEW CLIENT INSTALLATION - MICROSOFT FEB 2014 STUDENT Page 3 Virtual Desktop Login

  18. Creation Date: Mar 2014 Version: 1 Edited by: LB Application Services ITS Managed Document

    E-Print Network [OSTI]

    Northern British Columbia, University of

    Creation Date: Mar 2014 Version: 1 Edited by: LB Application Services ITS Managed Document VIEW Date: Mar 2014 Version: 1 Edited by: LB Application Services ITS Managed Document VIEW CLIENT Date: Mar 2014 Version: 1 Edited by: LB Application Services ITS Managed Document VIEW CLIENT

  19. Ultra High Temperature Rapid Thermal Annealing of GaN

    SciTech Connect (OSTI)

    Cao, X.A.; Fu, M.; Han, J.; Pearton, S.J.; Rieger, D.J.; Sekhar, J.A.; Shul, R.J.; Singh, R.K.; Wilson, R.G.; Zolper, J.C.

    1998-11-20T23:59:59.000Z

    All of the major acceptor (Mg, C, Be) and donor (Si, S, Se and Te) dopants have been implanted into GaN films grown on A1203 substrates. Annealing was performed at 1100- 1500 C, using AIN encapsulation. Activation percentages of >90Y0 were obtained for Si+ implantation annealed at 1400 C, while higher temperatures led to a decrease in both carrier concentration and electron mobility. No measurable redistribution of any of the implanted dopants was observed at 1450 C.

  20. Honors Enrichment Contracts Faculty View Page 1 Honors Enrichment Contracts Faculty View

    E-Print Network [OSTI]

    Honors Enrichment Contracts Faculty View Page 1 Honors Enrichment Contracts Faculty View INITIAL APPROVAL #12;Honors Enrichment Contracts Faculty View Page 2 Summary This document contains information about how to make initial and final decisions on Honors Enrichment Contracts submitted by honors

  1. ARM - News from the Gan Island Deployment

    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: National5Sales for4,645 3,625govInstrumentstdmadap Documentation TDMADAP : XDCnarrowbandheat fluxChinaNews : AMF Deployment,Media

  2. Submitted to J. Appl. Phys., revised October, 1999 1 A Rate Equation Model for the Growth of GaN on GaN(0001) by Molecular Beam Epitaxy

    E-Print Network [OSTI]

    Cohen, Philip I.

    Submitted to J. Appl. Phys., revised October, 1999 1 A Rate Equation Model for the Growth of GaN on GaN(0001) by Molecular Beam Epitaxy R.Held, B.E. Ishaug, A. Parkhomovsky, A.M. Dabiran, and P (October 7, 1999) GaN(0001)filmsweregrownbymolecularbeamepitaxyusingammoniaandelemental

  3. A3.2 Raman and IR studies of GaN C. Wetzel and I. Akasaki

    E-Print Network [OSTI]

    Wetzel, Christian M.

    energies in wurtzite and in zincblende GaN (Table 1.) [1-10]. Phonon and coupled modes have been employed of optical phonons modes in are very similar in wurtzite and cubic GaN. Selection rules in wurtzite allow to values in bulk GaN (Table 1): Table 1. Phonon modes in wurtzite GaN Symmetry active in Experiment (cm-1

  4. Intrinsic degradation mechanism of nearly lattice-matched InAlN layers grown on GaN substrates

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    1 Intrinsic degradation mechanism of nearly lattice-matched InAlN layers grown on GaN substrates compared to GaN, In0.17Al0.83N layers lattice-matched to GaN are an attractive solution for applications-standing (0001) GaN substrates with a low density of threading dislocations, for In compositions of 13.5% (layers

  5. GaN1-xBix: Extremely mismatched semiconductor alloys A. X. Levander,1,2

    E-Print Network [OSTI]

    Wu, Junqiao

    GaN1-xBix: Extremely mismatched semiconductor alloys A. X. Levander,1,2 K. M. Yu,1,a S. V. Novikov epitaxy, we have grown GaN1-xBix alloys on sapphire substrates with x up to 0.11. The GaN1-xBix alloys are found to be amorphous with GaN crystals distributed throughout the film. A dramatic reduction

  6. Local vibrational modes of the MgH acceptor complex in GaN W. Gotz,a)

    E-Print Network [OSTI]

    McCluskey, Matthew

    Local vibrational modes of the MgH acceptor complex in GaN W. Gotz,a) N. M. Johnson,b) and D. P are reported for Mg-doped GaN grown by metalorganic chemical vapor deposition. Hetero-epitaxial layers of GaN complex. The new LVMs are assigned to the stretch modes of the MgH and MgD complexes in GaN

  7. Morphology and surface reconstructions of GaN(1 1 00) surfaces C. D. Lee and R. M. Feenstra

    E-Print Network [OSTI]

    Feenstra, Randall

    assisted molecular beam epitaxy on ZnO(1 1 00) substrates. Well-oriented (1 1 00) GaN surfaces are obtained, ZnO offers an attractive substrate for GaN heteroepitaxy. We obtain well oriented (1 1 00) GaN films this structure consists of 2 monolayers of Ga terminating the GaN surface. ZnO(1 1 00) substrates were obtained

  8. Red light emission by photoluminescence and electroluminescence from Pr-doped GaN on Si substrates

    E-Print Network [OSTI]

    Steckl, Andrew J.

    Red light emission by photoluminescence and electroluminescence from Pr-doped GaN on Si substrates to higher level Er3 transitions. In this letter, we report on Pr-doped GaN growth on Si 111 substrates from Pr-doped GaN thin films grown on Si 111 . The GaN was grown by molecular beam epitaxy using solid

  9. Green emission from Er-doped GaN grown by molecular beam epitaxy on Si substrates

    E-Print Network [OSTI]

    Steckl, Andrew J.

    Green emission from Er-doped GaN grown by molecular beam epitaxy on Si substrates R. Birkhahn and A grown by MBE on sapphire substrates. In this letter, we report on Er-doped GaN growth experiments on Si Er-doped -GaN thin films grown on Si 111 . The GaN was grown by molecular beam epitaxy using solid

  10. GaN(0001) Surface Structures Studied Using Scanning Tunneling Microscopy and First-Principles Total Energy Calculations

    E-Print Network [OSTI]

    occurring on the (0001) surface of wurtzite GaN are studied using scanning tunneling microscopy, electron and electronic properties of wurtzite GaN surfaces. Several prior studies have reported that these surfaces do reconstructions were identified, corresponding to the two inequivalent polar fac- es of wurtzite GaN, the (0001

  11. Wurtzite GaN surface structures studied by scanning tunneling microscopy and reflection high energy electron diffraction

    E-Print Network [OSTI]

    Wurtzite GaN surface structures studied by scanning tunneling microscopy and reflection high energy-face of wurtzite GaN films grown using molecular beam epitaxy. N-face reconstructions are primarily adatom numerous surface studies of wurtzite GaN have been performed, progress in determining the true surface

  12. Phonon deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent Raman measurements

    E-Print Network [OSTI]

    Nabben, Reinhard

    Phonon deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent deformation potentials in wurtzite GaN and ZnO determined by uniaxial pressure dependent Raman measurements G online 9 February 2011 We report the phonon deformation potentials of wurtzite GaN and ZnO for all zone

  13. Mn-and Fe-doped GaN for spintronic applications Enno Malguth1,2

    E-Print Network [OSTI]

    Nabben, Reinhard

    Resonant Raman scattering on free and bound excitons in GaN A. Kaschner,* A. Hoffmann, and C Raman scattering effect in GaN at low temperatures applying a frequency-doubled titan-sapphire laser to detect inelastic scattered light from small sample volumes, for instance, in buried Al- GaN structures7

  14. Terahertz studies of carrier dynamics and dielectric response of n-type, freestanding epitaxial GaN

    E-Print Network [OSTI]

    Terahertz studies of carrier dynamics and dielectric response of n-type, freestanding epitaxial GaN conductivity and dielectric function of GaN by terahertz time-domain spectroscopy. Transmission measurements are performed on an n-type, 180- m-thick, freestanding GaN crystal. Frequency dependent electron dynamics, power

  15. Physica B 376377 (2006) 486490 Preferential substitution of Fe on physically equivalent Ga sites in GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    2006-01-01T23:59:59.000Z

    in GaN W. Gehlhoff, D. Azamat1 , U. Haboeck, A. Hoffmann Institute for Solid State Physics, Technical freestanding hydride vapor phase grown GaN have been studied in the X- and Q-band. A complex resonance pattern with C3v symmetry in the wurtzite structure of GaN. Aside from the displacement of their magnetic axis

  16. Comment on ``Shallow donors in GaN studied by electronic Raman scattering in resonance with yellow luminescence transitions''

    E-Print Network [OSTI]

    Nabben, Reinhard

    Photoluminescence and Raman study of compensation effects in Mg-doped GaN epilayers L. Eckey, U for publication 17 July 1998 The compensation of Mg-doped GaN is systematically studied by low in semiconductor technology during the recent years was the realization of p conductivity in GaN, leading

  17. Selective growth of high quality GaN on Si,,111... substrates M. Seon, T. Prokofyeva, and M. Holtza)

    E-Print Network [OSTI]

    Holtz, Mark

    Selective growth of high quality GaN on Si,,111... substrates M. Seon, T. Prokofyeva, and M. Holtza September 1999; accepted for publication 4 February 2000 We demonstrate selective growth of high-quality GaN by gas-source molecular beam epitaxy on Si 111 wafers patterned with SiO2. GaN was grown on wafers having

  18. Temperature dependent photoluminescence of lateral polarity junctions of metal organic chemical vapor deposition grown GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    implantation of Cu, Li and Ag into silicon doped GaN films grown by Metalorganic Chemical Vapor Deposition temperature (700-900C) annealing. Low temperature (6K) photoluminescence (PL) for Cu-implanted GaN showed recovery of standard crystalline GaN features. Additional donor-acceptor pair features are observed below 3

  19. Cathodoluminescence of stacking fault bound excitons for local probing of the exciton diffusion length in single GaN nanowires

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    length in single GaN nanowires Gilles Nogues,1, 2, a) Thomas Auzelle,3 Martien Den Hertog,1, 2 Bruno correlated studies of individual GaN nanowires in scanning electron microscopy combined to low temperature that carrier diffusion length in InGaN and GaN bidimensional (2D) layers are rather small, in the range of 50

  20. Oxidized GaN(0001) Surfaces studied by Scanning Tunneling Microscopy and Spectroscopy and by First-Principles Theory

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Oxidized GaN(0001) Surfaces studied by Scanning Tunneling Microscopy and Spectroscopy Abstract Oxidized Ga-polar GaN surfaces have been studied both experimentally and theoretically. For in tunneling spectroscopy revealed a surface band gap with size close to that of GaN, indicating that any

  1. PHYSICAL REVIEW B 86, 104114 (2012) Molecular dynamics of irradiation-induced defect production in GaN nanowires

    E-Print Network [OSTI]

    Nordlund, Kai

    2012-01-01T23:59:59.000Z

    in GaN nanowires Wei Ren,* Antti Kuronen, and Kai Nordlund Department of Physics, University of Helsinki the defect production of small-cross-section GaN nanowires by Ar ion irradiation. We performed 200 random production in the nanowires was increased by a factor of 2 compared to bulk GaN. A simple model to estimate

  2. Strain relaxation in GaN grown on vicinal 4H-SiC(0001) J. Pernot and E. Bustarret

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    Strain relaxation in GaN grown on vicinal 4H-SiC(0001) substrates J. Pernot and E. Bustarret, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands Abstract The strain of GaN layers grown by Metal Organic, the GaN layer grown on on-axis substrate has a slight and homogeneous tensile in-plane stress due

  3. Catalyst-Free GaN Nanowire Nucleation: Correlation of Temperature-Dependent Nanowire Orientation and Growth Matrix Changes

    E-Print Network [OSTI]

    Ayres, Virginia

    Catalyst-Free GaN Nanowire Nucleation: Correlation of Temperature-Dependent Nanowire Orientation nitride (GaN) nanowires have been under extensive investigation in recent years due to their unique that the GaN nanowires had internal structures that continued along the entire length of the nanowires

  4. Individual GaN Nanowires Exhibit Strong Piezoelectricity in 3D Majid Minary-Jolandan, Rodrigo A. Bernal, Irma Kuljanishvili,

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Individual GaN Nanowires Exhibit Strong Piezoelectricity in 3D Majid Minary-Jolandan, Rodrigo A, Northwestern University, Evanston, Illinois 60208, United States ABSTRACT: Semiconductor GaN NWs are promising, the electromechanical coupling leads to a third rank tensor that for wurtzite crystals (GaN NWs) possesses three

  5. The adsorption of oxygen at GaN surfaces Tosja K. Zywietz, a) Jo rg Neugebauer, and Matthias Scheffler

    E-Print Network [OSTI]

    The adsorption of oxygen at GaN surfaces Tosja K. Zywietz, a) Jo ? rg Neugebauer, and Matthias based on GaN is the controlled doping and the incorporation of impurities like, e.g., oxygen. We have explored the adsorption of oxygen at the wurtzite ~0001! and (0001 ? ) GaN surfaces employing density

  6. Radiative recombination and ultralong exciton photoluminescence lifetime in GaN freestanding film via two-photon excitation

    E-Print Network [OSTI]

    Radiative recombination and ultralong exciton photoluminescence lifetime in GaN freestanding film of a freestanding GaN film using one-photon and two-photon excitations to demonstrate the dramatic difference at 295 K is observed from a GaN freestanding film using two-photon excitation, whereas less than 100 ps

  7. Defect reduction in (112_O) a-plane GaN by two-stage epitaxial lateral overgrowth

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    c-axis (b) 50 ?m GaN c-axis (c) substrate window Ga wing NN wing (b) GaN c-axis 20 ?m (c) 10 ?m substrate Figure 3: (GaN films were grown on (1 102) r-plane sapphire substrates (

  8. Wafer-scale selective area growth of GaN hexagonal prismatic nanostructures on c-sapphire substrate

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    ;2 ABSTRACT Selective area growth of GaN nanostructures has been performed on full 2" c-sapphire substrates on GaN layer template grown on c-sapphire substrate and usually result in pyramid-shaped nanostructures of homogeneity of the nucleation selectivity of SAG GaN nanostructures on c- sapphire substrate remains an issue

  9. Scanning Tunneling Microscopy Study of Cr-doped GaN Surface Grown by RF Plasma Molecular Beam Epitaxy

    E-Print Network [OSTI]

    on sapphire substrate [2]. Park et al. performed the growth of Cr doped GaN single crystal by sodium fluxScanning Tunneling Microscopy Study of Cr-doped GaN Surface Grown by RF Plasma Molecular Beam Orleans, New Orleans, LA 70148, USA Abstract: Cr doped GaN was grown by rf N-plasma molecular beam epitaxy

  10. Focused ion beam micromilling of GaN and related substrate materials ,,sapphire, SiC, and Si...

    E-Print Network [OSTI]

    Steckl, Andrew J.

    Focused ion beam micromilling of GaN and related substrate materials ,,sapphire, SiC, and Si... A. In addition, we report similar results for materials currently utilized as substrates for GaN growth. II-0030 Received 15 October 1998; accepted 18 December 1998 Micromilling of GaN films has been obtained using a Ga

  11. Growth of p-type and n-type m-plane GaN by molecular beam epitaxy

    E-Print Network [OSTI]

    McLaurin, M; Mates, T E; Wu, F; Speck, J S

    2006-01-01T23:59:59.000Z

    other more conventional substrates for GaN growth. As anbetween the GaN ?lm and the SiC substrate is considered. 19oriented GaN ?lms were grown on 6H m-plane SiC substrates

  12. A Comparison of Magnesium and Beryllium Acceptors in GaN Grown by rf-Plasma Assisted Molecular Beam Epitaxy

    E-Print Network [OSTI]

    Myers, Tom

    as a function of substrate temperature and dopant flux for Ga-polarity and N-polarity GaN. Incorporation GaN templates on (0001) sapphire substrates. The doped layers were grown at a rate of 0.25 mA Comparison of Magnesium and Beryllium Acceptors in GaN Grown by rf-Plasma Assisted Molecular Beam

  13. Plasma-assisted molecular beam epitaxy of GaN on porous SiC substrates with varying porosity

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Plasma-assisted molecular beam epitaxy of GaN on porous SiC substrates with varying porosity York, 12222 Abstract: We have grown GaN on porous SiC substrates and studied the effect of substrate show that the GaN film grown on porous substrates contains open tubes and a low dislocation density

  14. Documenting Spreadsheets

    E-Print Network [OSTI]

    Payette, Raymond

    2008-01-01T23:59:59.000Z

    This paper discusses spreadsheets documentation and new means to achieve this end by using Excel's built-in "Comment" function. By structuring comments, they can be used as an essential tool to fully explain spreadsheet. This will greatly facilitate spreadsheet change control, risk management and auditing. It will fill a crucial gap in corporate governance by adding essential information that can be managed in order to satisfy internal controls and accountability standards.

  15. Hexagonal Growth Spirals on GaN Grown by Molecular Beam Epitaxy: Kinetics vs Thermodynamics

    E-Print Network [OSTI]

    Cohen, Philip I.

    prepared, Ga-polar GaN(0001) templates. The surface morphology was studied using reflection high-energy-edge energy of 0.26 eV/?. They suggest that local conditions at step edges dominate the growth. 1 conducted ex situ using AFM. Desorption mass spectrometry (DMS) was used to measure the GaN growth rate. Our

  16. Unoccupied band structure of wurtzite GaN,,0001... T. Valla and P. D. Johnson

    E-Print Network [OSTI]

    Homes, Christopher C.

    Unoccupied band structure of wurtzite GaN,,0001... T. Valla and P. D. Johnson Department of Physics of the unoccupied states of thin-film n-type wurtzite GaN. For incident electron energies below 30 eV, free of electronic devices based on heteroepitaxially grown wurtzite films of these nitrides.1 Extensive investiga

  17. K.K. Gan Siena02 1 The Ohio State University

    E-Print Network [OSTI]

    Gan, K. K.

    .K. Gan Siena02 6 l Decode Bi-Phase Mark encoded (BPM) clock and command signals from PIN diode l Input Error Rate (BER): BPM #12;K.K. Gan Siena02 7 l Training period: ~25 ms of 20 MHz clock (BPM with no data) DORIC Logic ] Ready

  18. Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy

    E-Print Network [OSTI]

    Myers, Tom

    Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy A. J. Ptak, L. J-assisted molecular-beam epitaxy to study the dependence of oxygen incorporation on polarity and oxygen partial pressure. Oxygen incorporates at a rate ten times faster on nitrogen-polar GaN than on the Ga polarity

  19. Structural effects of field emission from GaN nanofilms on SiC substrates

    SciTech Connect (OSTI)

    Chen, Cheng-Cheng; Wang, Ru-Zhi, E-mail: wrz@bjut.edu.cn; Zhu, Man-Kang; Yan, Hui [College of Materials Science and Engineering, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124 (China); Liu, Peng [Department of Physics Tsinghua University, Tsinghua-Foxconn Nanotechnology Research Center, Beijing 100084 (China); Wang, Bi-Ben [College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China)

    2014-04-21T23:59:59.000Z

    GaN nanofilms (NFs) with different structures are grown on SiC substrates by pulsed laser deposition under different conditions. The synthesized GaN NFs are studied by X-ray diffraction, field-emission (FE) scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The GaN NFs are composed of diversified GaN nanoparticles with a diameter of 938?nm, thickness of 1050?nm, and roughness of 0.2213.03?nm. FE from the GaN NFs is structure dependent, which is explained by stress changing the band gap of the NFs. By structure modulation, the turn-on field of GaN NFs can be as low as 0.66?V/?m at a current density of 1??A/cm{sup 2}, with a current density of up to 1.1?mA/cm{sup 2} at a field of 4.18?V/?m. Fowler-Nordheim curves of some samples contain multiple straight lines, which originate from the structural change and diversification of GaN nanoparticles under an applied field. Overall, our results suggest that GaN NFs with excellent FE properties can be prepared on SiC substrates, which provides a new route to fabricate high-efficiency FE nanodevices.

  20. Preparation and characterization of one-dimensional GaN nanorods with Tb intermediate layer

    SciTech Connect (OSTI)

    Shi, Feng, E-mail: sf751106@sina.com.cn [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)] [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Xue, Chengshan [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)] [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)

    2012-12-15T23:59:59.000Z

    Graphical abstract: Display Omitted Highlights: ? GaN nanorods have been prepared on Si substrates by magnetron sputtering. ? GaN nanorods are single crystal with hexagonal wurtzite structure. ? GaN nanorods are high-quality crystalline after ammoniating at 950 C for 15 min. ? Ammoniating temperatures and times affect the growth of GaN nanorods significantly. -- Abstract: GaN nanorods have been successfully prepared on Si(1 1 1) substrates by magnetron sputtering through ammoniating Ga{sub 2}O{sub 3}/Tb thin films. X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), FT-IR spectrophotometer, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and photoluminescence (PL) spectroscopy were used to characterize the microstructures, morphologies compositions and optical properties of the GaN samples. The results demonstrate that the nanorods are single crystal GaN with hexagonal wurtzite structure and high-quality crystalline after ammoniating at 950 C for 15 min, which have the size of 100150 nm in diameter. Ammoniating temperatures and times affect the growth of GaN nanorods significantly. The growth procedure mainly follows the Tb catalyst-assisted VLS mechanism.

  1. GaN light-emitting diodes with Archimedean lattice photonic crystals Aurlien David,a

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    GaN light-emitting diodes with Archimedean lattice photonic crystals Aurlien David,a Tetsuo Fujii 2005; published online 16 February 2006 We study GaN-based light emitting diodes incorporating the semiconductor due to its index contrast with air.16 Recently, PhCs were used as out- coupling gratings in GaN

  2. Fermi Level Control of Point Defects During Growth of Mg-Doped GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    Fermi Level Control of Point Defects During Growth of Mg-Doped GaN ZACHARY BRYAN,1,4 MARC HOFFMANN defects during metalorganic chem- ical vapor deposition (MOCVD) of Mg-doped GaN has been demonstrated of magnitude lower resistivity values compared with typical unan- nealed GaN:Mg samples. The PL spectra

  3. Anti-phase domains in cubic GaN Ricarda Maria Kemper,1,a)

    E-Print Network [OSTI]

    As, Donat Josef

    ) substrate morphology is studied with emphasis on the anti-phase domains (APDs). The GaN nucleation are the substrate of choice. There are three types of basic defects in epitaxial c-GaN thin films grown on 3CAnti-phase domains in cubic GaN Ricarda Maria Kemper,1,a) Thorsten Schupp,1 Maik Haberlen,1 Thomas

  4. Polarization anisotropy in GaN films for different nonpolar orientations studied by polarized photoreflectance spectroscopy

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    lms grown on GaN substrates. 1113 To determine ? cr and ?respective substrate. For optical spectra of GaN layers, theGaN ?lm ?sample III? also grown by PAMBE on ? -LiAlO 2 ?100? substrates.

  5. Zone-boundary phonons in hexagonal and cubic GaN H. Siegle, G. Kaczmarczyk, L. Filippidis, A. P. Litvinchuk, A. Hoffmann, and C. Thomsen

    E-Print Network [OSTI]

    Nabben, Reinhard

    Zone-boundary phonons in hexagonal and cubic GaN H. Siegle, G. Kaczmarczyk, L. Filippidis, A. P results of second-order Raman-scattering experiments on hexagonal and cubic GaN covering the acoustic- boundary phonons in hexagonal GaN. S0163-1829 97 01812-2 I. INTRODUCTION The wide-band-gap semiconductor GaN

  6. Hydrogen sensing characteristics of semipolar (112{sup }2) GaN Schottky diodes

    SciTech Connect (OSTI)

    Hyeon Baik, Kwang [School of Materials Science and Engineering, Hongik University, Jochiwon, Sejong 339-701 (Korea, Republic of); Kim, Hyonwoong; Jang, Soohwan, E-mail: jangmountain@dankook.ac.kr [Department of Chemical Engineering, Dankook University, Yongin 448-701 (Korea, Republic of); Lee, Sung-Nam [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung, Gyeonggi 429-793 (Korea, Republic of); Lim, Eunju [Department of Applied Physics, Institute of Nanosensor and Biotechnology, Dankook University, Yongin 448-701 (Korea, Republic of); Pearton, S. J. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Ren, F. [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-02-17T23:59:59.000Z

    The hydrogen detection characteristics of semipolar (112{sup }2) plane GaN Schottky diodes were investigated and compared to c-plane Ga- and N-polar and nonpolar a-plane (112{sup }0) GaN diodes. The semipolar GaN diodes showed large current response to 4% hydrogen in nitrogen gas with an accompanying Schottky barrier reduction of 0.53?eV at 25?C, and the devices exhibited full recovery to the initial current level upon switching to a nitrogen ambient. The current-voltage characteristics of the semipolar devices remained rectifying after hydrogen exposure, in sharp contrast to the case of c-plane N-polar GaN. These results show that the surface atom configuration and polarity play a strong role in hydrogen sensing with GaN.

  7. Step-induced misorientation of GaN grown on r-plane sapphire

    SciTech Connect (OSTI)

    Smalc-Koziorowska, J.; Dimitrakopulos, G. P.; Sahonta, S.-L.; Komninou, Ph. [Physics Department, Aristotle University, GR 54124 Thessaloniki (Greece); Tsiakatouras, G.; Georgakilas, A. [Microelectronics Research Group, Department of Physics, University of Crete, P.O. Box 2208, GR 71003, and IESL, FORTH, P.O. Box 1527, GR 71110 Heraklion (Greece)

    2008-07-14T23:59:59.000Z

    In the growth of nonpolar (1120) a-plane GaN on r-plane (1102) sapphire by plasma-assisted molecular beam epitaxy, misoriented crystallites are observed close to the substrate. They have average diameter {approx}10 nm and are oriented with the (0001){sub GaN} plane approximately parallel to the (2113){sub sapph.} plane and [0110]{sub GaN} parallel [1101]{sub sapph.}. This semipolar orientation is promoted by a low misfit (2.4%) between (1011){sub GaN} and (1210){sub sapph.} planes. Its introduction, after nitridation treatment, is due to GaN nucleation on (2113){sub sapph.} step facets inclined at 26 deg. relative to the r-plane. Two variants are observed, leading to twinning when they abut inside the epilayer.

  8. Polarity of semipolar wurtzite crystals: X-ray photoelectron diffraction from GaN(101?1) and GaN(202?1) surfaces

    SciTech Connect (OSTI)

    Romanyuk, O., E-mail: romanyuk@fzu.cz; Ji??ek, P.; Barto, I. [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnick 10, 162 53 Prague (Czech Republic); Paskova, T. [Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27606 (United States)

    2014-09-14T23:59:59.000Z

    Polarity of semipolar GaN(101?1) (101?1?) and GaN(202?1) (202?1?) surfaces was determined with X-ray photoelectron diffraction (XPD) using a standard MgK? source. The photoelectron emission from N 1s core level measured in the a-plane of the crystals shows significant differences for the two crystal orientations within the polar angle range of 80100 from the (0001) normal. It was demonstrated that XPD polar plots recorded in the a-plane are similar for each polarity of the GaN(101?1) and GaN(202?1) crystals if referred to (0001) crystal axes. For polarity determinations of all important GaN(h0h?l) semipolar surfaces, the above given polar angle range is suitable.

  9. Surface morphology evolution of m-plane (1100) GaN during molecular beam epitaxy growth: Impact of Ga/N ratio, miscut direction, and growth temperature

    SciTech Connect (OSTI)

    Shao Jiayi; Tang Liang; Malis, Oana [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Edmunds, Colin [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Gardner, Geoff [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Manfra, Michael [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2013-07-14T23:59:59.000Z

    We present a systematic study of morphology evolution of [1100] m-plane GaN grown by plasma-assisted molecular beam epitaxy on free-standing m-plane substrates with small miscut angles towards the -c [0001] and +c [0001] directions under various gallium to nitrogen (Ga/N) ratios at substrate temperatures T = 720 Degree-Sign C and T = 740 Degree-Sign C. The miscut direction, Ga/N ratio, and growth temperature are all shown to have a dramatic impact on morphology. The observed dependence on miscut direction supports the notion of strong anisotropy in the gallium adatom diffusion barrier and growth kinetics. We demonstrate that precise control of Ga/N ratio and substrate temperature yields atomically smooth morphology on substrates oriented towards +c [0001] as well as the more commonly studied -c [0001] miscut substrates.

  10. Document13

    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: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisitingContract ManagementDiscovering How Muscles ReallyDDT DDTViewDoDocument

  11. Reference Documents

    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 PossibleRadiation Protection RadiationRecord-SettingHead ofReference-Documents Sign In About |

  12. Document Information

    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: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign:INEA : Papers69 Federal Register / Vol. 71, No.5 Document

  13. GaN directional couplers for integrated quantum photonics

    E-Print Network [OSTI]

    Yanfeng Zhang; Loyd McKnight; Erman Engin; Ian M. Watson; Martin J. Cryan; Erdan Gu; Mark G. Thompson; Stephane Calvez; Jeremy L. O'Brien; Martin D. Dawson

    2012-02-20T23:59:59.000Z

    Large cross-section GaN waveguides are proposed as a suitable architecture to achieve integrated quantum photonic circuits. Directional couplers with this geometry have been designed with aid of the beam propagation method and fabricated using inductively coupled plasma etching. Scanning electron microscopy inspection shows high quality facets for end coupling and a well defined gap between rib pairs in the coupling region. Optical characterization at 800 nm shows single-mode operation and coupling-length-dependent splitting ratios. Two photon interference of degenerate photon pairs has been observed in the directional coupler by measurement of the Hong-Ou-Mandel dip with 96% visibility.

  14. Synthesis, structure, and optical properties of colloidal GaN quantum dots

    SciTech Connect (OSTI)

    Micic, O.I.; Ahrenkiel, S.P.; Bertram, D.; Nozik, A.J. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    1999-07-01T23:59:59.000Z

    Colloidal chemistry was used to synthesize GaN quantum dots. A GaN precursor, polymeric gallium imide, {l_brace}Ga(NH){sub 3/2}{r_brace}{sub n}, which was prepared by the reaction of dimeric amidogallium with ammonia at room temperature, was heated in trioctylamine at 360&hthinsp;{degree}C for one day to produce GaN nanocrystals. The GaN particles were separated, purified, and partially dispersed in a nonpolar solvent to yield transparent colloidal solutions that consisted of individual GaN particles. The GaN nanocrystals have a spherical shape and mean diameter of about 30{plus_minus}12&hthinsp;{Angstrom}. The spectroscopic behavior of colloidal transparent dispersion has been investigated and shows that the band gap of the GaN nanocrystals shifts to slightly higher energy due to quantum confinement. The photoluminescence spectrum at 10 K (excited at 310 nm) shows band edge emission with several emission peaks in the range between 3.2 and 3.8 eV, while the photoluminescence excitation spectrum shows two excited-state transitions at higher energies. {copyright} {ital 1999 American Institute of Physics.}

  15. Growth of GaN on Ge(111) by molecular beam epitaxy

    SciTech Connect (OSTI)

    Lieten, R. R.; Degroote, S.; Cheng, K.; Leys, M.; Kuijk, M.; Borghs, G. [MCP/ART, IMEC, Kapeldreef 75, 3001 Leuven (Belgium) and ETRO, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); MCP/ART, IMEC, Kapeldreef 75, 3001 Leuven (Belgium); ETRO, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium); MCP/ART, IMEC, Kapeldreef 75, 3001 Leuven (Belgium)

    2006-12-18T23:59:59.000Z

    The epitaxial growth of GaN on Ge is reported. The authors found that direct growth of GaN performs exceptionally well on Ge(111) with plasma assisted molecular beam epitaxy. A streaky reflection high energy electron diffraction pattern is observed during growth. X-ray diffraction showed a rocking curve full width at half maximum of only 371 arc sec for a 38 nm GaN layer and indicates an abrupt interface between the GaN and Ge. Secondary ion mass spectrometry shows limited diffusion of Ga atoms into the Ge substrate and Ge atoms into the GaN layers. Current-voltage measurements show rectifying behavior for n-GaN on p-Ge. Their results indicate that GaN growth on Ge does not require intermediate layers, allowing the Ge substrate to be used as back contact in vertical devices. A p-n junction formed between GaN and Ge can be used in heterojunction devices.

  16. Plans, Updates, Regulatory Documents

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

    Stewardship Environmental Protection Obeying Environmental Laws Individual Permit Documents Individual Permit: Plans, Updates, Regulatory Documents1335769200000Plans...

  17. XML Document XML Document Types and Validation

    E-Print Network [OSTI]

    Weber, Gregory D.

    XML Document Types and Validation IIM-I340 Objectives XML Document Types and Validation IIM-I340 April, 2010 #12;XML Document Types and Validation IIM-I340 Objectives Learning Objectives Understand: The need for validation Two ways to specify validity: Document Type Definitions (DTDs) XML Schemas #12;XML

  18. Highly c-axis oriented growth of GaN film on sapphire (0001) by laser molecular beam epitaxy using HVPE grown GaN bulk target

    SciTech Connect (OSTI)

    Kushvaha, S. S.; Kumar, M. Senthil; Maurya, K. K.; Dalai, M. K.; Sharma, Nita D. [CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, India 110012 (India)] [CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, India 110012 (India)

    2013-09-15T23:59:59.000Z

    Growth temperature dependant surface morphology and crystalline properties of the epitaxial GaN layers grown on pre-nitridated sapphire (0001) substrates by laser molecular beam epitaxy (LMBE) were investigated in the range of 500750 C. The grown GaN films were characterized using high resolution x-ray diffraction, atomic force microscopy (AFM), micro-Raman spectroscopy, and secondary ion mass spectroscopy (SIMS). The x-ray rocking curve full width at a half maximum (FWHM) value for (0002) reflection dramatically decreased from 1582 arc sec to 153 arc sec when the growth temperature was increased from 500 C to 600 C and the value further decreased with increase of growth temperature up to 720 C. A highly c-axis oriented GaN epitaxial film was obtained at 720 C with a (0002) plane rocking curve FWHM value as low as 102 arc sec. From AFM studies, it is observed that the GaN grain size also increased with increasing growth temperature and flat, large lateral grains of size 200-300 nm was obtained for the film grown at 720 C. The micro-Raman spectroscopy studies also exhibited the high-quality wurtzite nature of GaN film grown on sapphire at 720 C. The SIMS measurements revealed a non-traceable amount of background oxygen impurity in the grown GaN films. The results show that the growth temperature strongly influences the surface morphology and crystalline quality of the epitaxial GaN films on sapphire grown by LMBE.

  19. X-Ray Studies of GaN Film Grown on Si Using Electrochemical Deposition Techniques

    SciTech Connect (OSTI)

    Al-Heuseen, K.; Hashim, M. R. [Nano-Optoelectronics Research and Technology Laboratory School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang (Malaysia)

    2011-03-30T23:59:59.000Z

    This paper reports on the X-ray studies of GaN thin films deposited on Si (111) substrate at different current density using electrochemical deposition technique. The structural properties of GaN films were studied by X-ray diffraction (XRD). XRD analysis showed that hexagonal wurtzite and cubic zinc blende GaN phases were both deposited on Si (111). The lattice constants, the average size of h-GaN crystals and the in-plane (along a-axis) and out of plane (along c-axis) strains were calculated from XRD analysis.

  20. Omega documentation

    SciTech Connect (OSTI)

    Howerton, R.J.; Dye, R.E.; Giles, P.C.; Kimlinger, J.R.; Perkins, S.T.; Plechaty, E.F.

    1983-08-01T23:59:59.000Z

    OMEGA is a CRAY I computer program that controls nine codes used by LLNL Physical Data Group for: 1) updating the libraries of evaluated data maintained by the group (UPDATE); 2) calculating average values of energy deposited in secondary particles and residual nuclei (ENDEP); 3) checking the libraries for internal consistency, especially for energy conservation (GAMCHK); 4) producing listings, indexes and plots of the library data (UTILITY); 5) producing calculational constants such as group averaged cross sections and transfer matrices for diffusion and Sn transport codes (CLYDE); 6) producing and updating standard files of the calculational constants used by LLNL Sn and diffusion transport codes (NDFL); 7) producing calculational constants for Monte Carlo transport codes that use group-averaged cross sections and continuous energy for particles (CTART); 8) producing and updating standard files used by the LLNL Monte Carlo transport codes (TRTL); and 9) producing standard files used by the LANL pointwise Monte Carlo transport code MCNP (MCPOINT). The first four of these functions and codes deal with the libraries of evaluated data and the last five with various aspects of producing calculational constants for use by transport codes. In 1970 a series, called PD memos, of internal and informal memoranda was begun. These were intended to be circulated among the group for comment and then to provide documentation for later reference whenever questions arose about the subject matter of the memos. They have served this purpose and now will be drawn upon as source material for this more comprehensive report that deals with most of the matters covered in those memos.

  1. Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1-xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    fabricated on freestanding GaN substrates T. Koyama and T.on freestanding m-plane GaN substrates. Although the ? inton the freestanding GaN substrate. cause the current was

  2. Millimeter-wave GaN high electron mobility transistors and their integration with silicon electronics

    E-Print Network [OSTI]

    Chung, Jinwook W. (Jinwook Will)

    2011-01-01T23:59:59.000Z

    In spite of the great progress in performance achieved during the last few years, GaN high electron mobility transistors (HEMTs) still have several important issues to be solved for millimeter-wave (30 ~ 300 GHz) applications. ...

  3. Light extraction in individual GaN nanowires on Si for LEDs

    E-Print Network [OSTI]

    Zhou, Xiang

    GaN-based nanowires hold great promise for solid state lighting applications because of their waveguiding properties and the ability to grow nonpolar GaN nanowire-based heterostructures, which could lead to increased light ...

  4. Chromatin Ionic Atmosphere Analyzed by a Mesoscale Electrostatic Hin Hark Gan

    E-Print Network [OSTI]

    Schlick, Tamar

    Chromatin Ionic Atmosphere Analyzed by a Mesoscale Electrostatic Approach Hin Hark Gan and Tamar an electrostatic model to handle multivalent ions and compute the ionic distribution around a mesoscale chromatin

  5. Thermal Conductivity and Large Isotope Effect in GaN from First Principles

    SciTech Connect (OSTI)

    Lindsay, L. [Naval Research Lab. (NRL), Washington, DC (United States); Broido, D. A. [Boston College, Chestnut Hill, MA (United States); Reinecke, T. L. [Naval Research Lab. (NRL), Washington, DC (United States)

    2012-08-01T23:59:59.000Z

    We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb. In GaN we find a large increase to the thermal conductivity with isotopic enrichment, ~65% at room temperature. We show that both the high thermal conductivity and its enhancement with isotopic enrichment in GaN arise from the weak coupling of heat-carrying acoustic phonons with optic phonons. This weak scattering results from stiff atomic bonds and the large Ga to N mass ratio, which give phonons high frequencies and also a pronounced energy gap between acoustic and optic phonons compared to other materials. Rigorous understanding of these features in GaN gives important insights into the interplay between intrinsic phonon-phonon scattering and isotopic scattering in a range of materials.

  6. Atomic-Level Study of Melting Behavior of GaN Nanotubes. | EMSL

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

    Behavior of GaN Nanotubes. Abstract: Molecular dynamics simulations with a Stillinger-Weber potential have been used to investigate the melting behavior of wurtzite-type single...

  7. RF Power Degradation of GaN High Electron Mobility Transistors

    E-Print Network [OSTI]

    Joh, Jungwoo

    We have developed a versatile methodology to systematically investigate the RF reliability of GaN High-Electron Mobility Transistors. Our technique utilizes RF and DC figures of merit to diagnose the degradation of RF ...

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

    E-Print Network [OSTI]

    Zhou, Xiang

    We report the nanoscale optical investigation of a single GaN p-n junction nanorod by cathodoluminescence (CL) in a scanning transmission electron microscope. CL emission characteristic of dopant-related transitions was ...

  9. Above room-temperature ferromagnetism of Mn delta-doped GaN nanorods

    SciTech Connect (OSTI)

    Lin, Y. T.; Wadekar, P. V.; Kao, H. S.; Chen, T. H.; Chen, Q. Y.; Tu, L. W., E-mail: lwtu@faculty.nsysu.edu.tw [Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Huang, H. C.; Ho, N. J. [Department of Materials and Optoelectronic Science and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

    2014-02-10T23:59:59.000Z

    One-dimensional nitride based diluted magnetic semiconductors were grown by plasma-assisted molecular beam epitaxy. Delta-doping technique was adopted to dope GaN nanorods with Mn. The structural and magnetic properties were investigated. The GaMnN nanorods with a single crystalline structure and with Ga sites substituted by Mn atoms were verified by high-resolution x-ray diffraction and Raman scattering, respectively. Secondary phases were not observed by high-resolution x-ray diffraction and high-resolution transmission electron microscopy. In addition, the magnetic hysteresis curves show that the Mn delta-doped GaN nanorods are ferromagnetic above room temperature. The magnetization with magnetic field perpendicular to GaN c-axis saturates easier than the one with field parallel to GaN c-axis.

  10. Reliability of GaN high electron mobility transistors on silicon substrates

    E-Print Network [OSTI]

    Demirtas, Sefa

    2009-01-01T23:59:59.000Z

    GaN High Electron Mobility Transistors are promising devices for high power and high frequency applications such as cellular base stations, radar and wireless network systems, due to the high bandgap and high breakdown ...

  11. Development of strain reduced GaN on Si (111) by substrate engineering

    SciTech Connect (OSTI)

    Jamil, M.; Grandusky, J.R.; Jindal, V.; Shahedipour-Sandvik, F.; Guha, S.; Arif, M. [College of Nanoscale Science and Engineering, University at Albany-State University of New York, 255 Fuller Rd, Albany, New York 12203 (United States); Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

    2005-08-22T23:59:59.000Z

    We report on a novel scheme of substrate engineering to obtain high-quality GaN layers on Si substrates. Ion implantation of an AlN/Si substrate is performed to create a defective layer that partially isolates the III-nitride layer and the Si substrate and helps to reduce the strain in the film. Raman spectroscopy shows a substantial decrease in in-plane strain in GaN films grown on nitrogen implanted substrates. This is confirmed by the enhancement of the E{sub 2} (TO) phonon frequency from 564 to 567 cm{sup -1} corresponding to 84% stress reduction and substantial decrease in crack density for a 2-{mu}m-thick GaN film. GaN films grown on implanted AlN/Si substrate have better optical properties and smoother surface morphology as compared to nonimplanted AlN/Si substrate.

  12. Radiative defects in GaN nanocolumns: Correlation with growth conditions and sample morphology

    SciTech Connect (OSTI)

    Lefebvre, P.; Fernandez-Garrido, S.; Grandal, J.; Ristic, J.; Sanchez-Garcia, M.-A.; Calleja, E. [Instituto de Sistemas Optoelectronicos y Microtecnologia, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2011-02-21T23:59:59.000Z

    Low-temperature photoluminescence is studied in detail in GaN nanocolumns (NCs) grown by plasma-assisted molecular beam epitaxy under various conditions (substrate temperature and impinging Ga/N flux ratio). The relative intensities of the different emission lines, in particular those related to structural defects, appear to be correlated with the growth conditions, and clearly linked to the NC sample morphology. We demonstrate, in particular, that all lines comprised between 3.10 and 3.42 eV rapidly lose intensity when the growth conditions are such that the NC coalescence is reduced. The well-known line around 3.45 eV, characteristic of GaN NC samples, shows, however, a behavior that is exactly the opposite of the other lines, namely, for growth conditions leading to reduced NC coalescence, this line tends to become more prominent, thus proving to be intrinsic to individual GaN NCs.

  13. Measurement of Channel Temperature in GaN High-Electron Mobility Transistors

    E-Print Network [OSTI]

    Joh, Jungwoo

    In this paper, a simple and reliable method to estimate the channel temperature of GaN high-electron mobility transistors (HEMTs) is proposed. The technique is based on electrical measurements of performance-related figures ...

  14. The study of in situ scanning tunnelling microscope characterization on GaN thin film grown by plasma assisted molecular beam epitaxy

    SciTech Connect (OSTI)

    Yang, R.; Krzyzewski, T.; Jones, T. [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom)] [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2013-03-18T23:59:59.000Z

    The epitaxial growth of GaN by Plasma Assisted Molecular Beam Epitaxy was investigated by Scanning Tunnelling Microscope (STM). The GaN film was grown on initial GaN (0001) and monitored by in situ Reflection High Energy Electron Diffraction and STM during the growth. The STM characterization was carried out on different sub-films with increased thickness. The growth of GaN was achieved in 3D mode, and the hexagonal edge of GaN layers and growth gradient were observed. The final GaN was of Ga polarity and kept as (0001) orientation, without excess Ga adlayers or droplets formed on the surface.

  15. Optical Properties of Mn-doped GaN O. Gelhausen1

    E-Print Network [OSTI]

    Nabben, Reinhard

    measurements. In the GaN:Mn, an intense absorption peak at 1.414 +/- 0.002 eV was observed. This peakOptical Properties of Mn-doped GaN O. Gelhausen1 , E. Malguth1,3 , M. R. Phillips1 , E. M. Goldys2, Germany ABSTRACT Molecular beam epitaxy-grown GaN with different Mn concentrations (5-23 x 1019 cm-3

  16. Low temperature thin film transistors with hollow cathode plasma-assisted atomic layer deposition based GaN channels

    SciTech Connect (OSTI)

    Bolat, S., E-mail: bolat@ee.bilkent.edu.tr, E-mail: aokyay@ee.bilkent.edu.tr; Tekcan, B. [Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800 (Turkey); UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Ozgit-Akgun, C.; Biyikli, N. [UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Okyay, A. K., E-mail: bolat@ee.bilkent.edu.tr, E-mail: aokyay@ee.bilkent.edu.tr [Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800 (Turkey); UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)

    2014-06-16T23:59:59.000Z

    We report GaN thin film transistors (TFT) with a thermal budget below 250?C. GaN thin films are grown at 200?C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3?nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (I{sub ON}/I{sub OFF}) of 10{sup 3} and sub-threshold swing of 3.3?V/decade. The entire TFT device fabrication process temperature is below 250?C, which is the lowest process temperature reported for GaN based transistors, so far.

  17. Behavior of aluminum adsorption and incorporation at GaN(0001) surface: First-principles study

    SciTech Connect (OSTI)

    Qin, Zhenzhen; Xiong, Zhihua, E-mail: xiong-zhihua@126.com; Wan, Qixin [Key Laboratory for Optoelectronics and Communication of Jiangxi Province, Jiangxi Science and Technology Normal University, Nanchang 330018 (China); Qin, Guangzhao [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, University of Chinese Academy of Sciences, Beijing 101408 (China)

    2013-11-21T23:59:59.000Z

    First-principles calculations are performed to study the energetics and atomic structures of aluminum adsorption and incorporation at clean and Ga-bilayer GaN(0001) surfaces. We find the favorable adsorption site changes from T4 to T1 as Al coverage increased to 1 monolayer on the clean GaN(0001) surface, and a two-dimensional hexagonal structure of Al overlayer appears. It is interesting the Al atoms both prefer to concentrate in one deeper Ga layer of clean and Ga-bilayer GaN(0001) surface, respectively, while different structures could be achieved in above surfaces. For the case of clean GaN(0001) surface, corresponding to N-rich and moderately Ga-rich conditions, a highly regular superlattice structure composed of wurtzite GaN and AlN becomes favorable. For the case of Ga-bilayer GaN(0001) surface, corresponding to extremely Ga-rich conditions, the Ga bilayer is found to be sustained stable in Al incorporating process, leading to an incommensurate structure directly. Furthermore, our calculations provide an explanation for the spontaneous formation of ordered structure and incommensurate structure observed in growing AlGaN films. The calculated results are attractive for further development of growth techniques and excellent AlGaN/GaN heterostructure electronic devices.

  18. Nondestructive characterization of GaN films grown at low and high temperatures

    SciTech Connect (OSTI)

    Yan, C.H.; Yao, H.W.; Hove, J.M. van; Wowchak, A.M.; Chow, P.P.; Han, J.; Zavada, J.M.

    2000-07-01T23:59:59.000Z

    GaN films grown on GaAs and sapphire substrates by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) at both low and high temperatures (LT and HT) were characterized by Raman scattering and variable angle spectroscopic ellipsometry (VASE). Optical phonon spectra of GaN films are obtained through back-scattering geometry. Crystal quality of these films was qualitatively examined using phonon line-width. Phonon spectra showed that the HT GaN has wurtzite crystal structure, while LT GaN and GaN/GaAs have cubic-like structures. Thickness nonuniformity and defect-related absorption can be characterized by pseudo dielectric functions directly. Surface roughness also can be determined by using an effective-medium approximation (EMA) over-layer in a VASE analysis. Anisotropic optical constants of GaN, both ordinary and extraordinary, were obtained in the spectral range of 0.75 to 6.5 eV with the consideration of surface roughness, through the small and large angles of incidence, respectively. The film thickness of the GaN was accurately determined via the analysis as well.

  19. Deposition of CVD diamond onto GaN P.W. May a,*, H.Y. Tsai b

    E-Print Network [OSTI]

    Bristol, University of

    of the polycrystalline diamond surface would prevent light from leaking out of the GaN layer and channel it to the endsDeposition of CVD diamond onto GaN P.W. May a,*, H.Y. Tsai b , W.N. Wang c , J.A. Smith a a School performed to deposit continuous layers of CVD diamond onto epitaxial GaN films. Such diamond coatings would

  20. Molecular Beam Epitaxial Growth of Zinc-Blende FeN(111) on Wurtzite GaN(0001)

    E-Print Network [OSTI]

    Molecular Beam Epitaxial Growth of Zinc-Blende FeN(111) on Wurtzite GaN(0001) Wenzhi Lin, Jeongihm], but not hexagonal (wurtzite) GaN, a fast-developing semiconductor material with important technological applicationsN on wurtzite GaN(0001), by employing e-beam evaporation in an ultra-high vacuum MBE cham- ber. The FeN films

  1. Calculated second-harmonic susceptibilities of BN, AlN, and GaN Jian Chen,a)

    E-Print Network [OSTI]

    Wilkins, John

    and the second-harmonic susceptibility d for BN, AlN, and GaN in both zincblende and wurtzite structures within the KohnSham local-density approximation. For wurtzite AlN and GaN, the computed dxxz (w) and dzzz (w) closely agree with experiment. For zincblende AlN and GaN as well as zincblende and wurtzite BN, we

  2. Doping of GaN12xAsx with high As content A. X. Levander,1,2

    E-Print Network [OSTI]

    Wu, Junqiao

    Doping of GaN12xAsx with high As content A. X. Levander,1,2 S. V. Novikov,3 Z. Liliental-Weber,1 R; published online 2 November 2011) Recent work has shown that GaN1xAsx can be grown across the entire report the bipolar doping of GaN1xAsx with high As content to conductivities above 4 S=cm at room

  3. Role of nitrogen vacancies in the luminescence of Mg-doped GaN Qimin Yan,1

    E-Print Network [OSTI]

    Role of nitrogen vacancies in the luminescence of Mg-doped GaN Qimin Yan,1 Anderson Janotti,1 or act as recombination centers in Mg- doped GaN is essential for improving the performance of group-vacancy complexes (MgGa-VN) on the electrical and optical properties of GaN. We find that MgGa-VN are compensating

  4. The adsorption of oxygen at GaN surfaces Tosja K. Zywietz, Jrg Neugebauer, and Matthias Scheffler

    E-Print Network [OSTI]

    The adsorption of oxygen at GaN surfaces Tosja K. Zywietz, Jörg Neugebauer, and Matthias Scheffler://apl.aip.org/about/rights_and_permissions #12;The adsorption of oxygen at GaN surfaces Tosja K. Zywietz,a) Jo¨rg Neugebauer, and Matthias based on GaN is the controlled doping and the incorporation of impurities like, e.g., oxygen. We have

  5. Low gap amorphous GaN1-xAsx alloys grown on glass substrate K. M. Yu,1,a

    E-Print Network [OSTI]

    Wu, Junqiao

    Low gap amorphous GaN1-xAsx alloys grown on glass substrate K. M. Yu,1,a S. V. Novikov,2 R September 2010 Amorphous GaN1-xAsx layers with As content in the range of x=0.1 to 0.6 were grown defined optical absorption edges. The measured band gap values for the crystalline and amorphous GaN1-x

  6. Comparison of strong coupling regimes in bulk GaAs, GaN and ZnO semiconductor microcavities

    E-Print Network [OSTI]

    Boyer, Edmond

    , transmission and absorption spectra of bulk GaAs, GaN and ZnO microcavities, in order to compareComparison of strong coupling regimes in bulk GaAs, GaN and ZnO semiconductor microcavities SAs and GaN microcavities. PACS numbers: 78.67.-n, 71.36.+c, 78.20.Ci, 78.55.Cr, 78.55.Et Keywords: polariton

  7. Thermal Stability of MOCVD and HVPE GaN Layers in H2, HCl, NH3 and N2

    E-Print Network [OSTI]

    Anderson, Timothy J.

    GaN, and the black is the sapphire substrate. At 900 C nearly 1/4 of the film has sublimated leavingThermal Stability of MOCVD and HVPE GaN Layers in H2, HCl, NH3 and N2 M. A. Mastro1 ) (a), O. M.60.Dv; 81.15.Gh; S7.14 This work represents a complete study of GaN annealed in H2, HCl, NH3 and N2

  8. Transition between wurtzite and zinc-blende GaN: An effect of deposition condition of molecular-beam epitaxy

    SciTech Connect (OSTI)

    Shi, B. M.; Xie, M. H.; Wu, H. S.; Wang, N.; Tong, S. Y. [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tang, Hong Kong (China)

    2006-10-09T23:59:59.000Z

    GaN exists in both wurtzite and zinc-blende phases and the growths of the two on its (0001) or (111) surfaces are achieved by choosing proper deposition conditions of molecular-beam epitaxy (MBE). At low substrate temperatures but high gallium fluxes, metastable zinc-blende GaN films are obtained, whereas at high temperatures and/or using high nitrogen fluxes, equilibrium wurtzite phase GaN epilayers resulted. This dependence of crystal structure on substrate temperature and source flux is not affected by deposition rate. Rather, the initial stage nucleation kinetics plays a primary role in determining the crystallographic structures of epitaxial GaN by MBE.

  9. Research Data Management - Documentation

    E-Print Network [OSTI]

    Collins, Anna

    2013-01-01T23:59:59.000Z

    This short (16 slide) presentation "Documentation" explains the need to create documentation using several clear examples of the benefits from good documentation (and what can happen if it is not good), making research reproducible...

  10. Sandia Energy - SCADA Documents

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

    Documents Home Stationary Power Grid Modernization Cyber Security for Electric Infrastructure National Supervisory Control and Data Acquisition (SCADA) SCADA Documents SCADA...

  11. Impact of substrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN grown by molecular beam epitaxy

    E-Print Network [OSTI]

    Armstrong, A; Poblenz, C; Green, D S; Mishra, U K; Speck, J S; Ringel, S A

    2006-01-01T23:59:59.000Z

    GaN grown by molecular beam epitaxy and codoped with carbon and silicon were investigated for substratesubstrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN

  12. 596 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 41, NO. 4, APRIL 2005 Nanoscale Spatial Phase Modulation of GaN on

    E-Print Network [OSTI]

    New Mexico, University of

    Modulation of GaN on a V-Grooved Si Substrate--Cubic Phase GaN on Si(001) for Monolithic Integration S. C Abstract--Nanoscale spatial phase modulation of GaN gorwn on a 355-nm period array of V-grooves fabricated in a Si(001) substrate is reported. Orientation-dependent selective nucleation of GaN in metal

  13. Energetics of H and NH2 on GaN,,1010... and implications for the origin of nanopipe defects John E. Northrup and R. Di Felice

    E-Print Network [OSTI]

    Energetics of H and NH2 on GaN,,101¯0... and implications for the origin of nanopipe defects John E-terminated GaN 101¯0 surfaces. The calculations indicate that H adsorption on GaN 101¯0 will proceed. The implications of these results for the origin of nanopipe defects in GaN are examined. S0163-1829 97 51832

  14. IPAP Conference Series 1: IWN2000, Nov., 2000 1 Morphology Dependent Growth Kinetics of Ga-polar GaN(0001)

    E-Print Network [OSTI]

    Cohen, Philip I.

    IPAP Conference Series 1: IWN2000, Nov., 2000 1 Morphology Dependent Growth Kinetics of Ga-polar GaN, cohen@ece.umn.edu GaN grown on Ga polar GaN templates prepared by metal-organic vapor deposition shows to equilibrium models of the growth. The results indicate that Ga-polar GaN(0001) has a step energy of the order

  15. Crystallographically tilted and partially strain relaxed GaN grown on inclined (111) facets etched on Si(100) substrate

    SciTech Connect (OSTI)

    Ansah Antwi, K. K. [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Institute of Materials Research and Engineering, 3 Research Link, 117602 Singapore (Singapore); Soh, C. B. [Singapore Institute of Technology, 10 Dover Drive, Singapore 138683 (Singapore); Wee, Q. [Singapore-MIT Alliance, National University of Singapore, Singapore 117576 (Singapore); Tan, Rayson J. N.; Tan, H. R. [Institute of Materials Research and Engineering, 3 Research Link, 117602 Singapore (Singapore); Yang, P. [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, 117603 Singapore (Singapore); Sun, L. F.; Shen, Z. X. [School of Physical and Mathematical Sciences, Nanyang Technological University, SPMS-03-01, 21 Nanyang Link (Singapore); Chua, S. J., E-mail: elecsj@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Institute of Materials Research and Engineering, 3 Research Link, 117602 Singapore (Singapore); Singapore-MIT Alliance, National University of Singapore, Singapore 117576 (Singapore)

    2013-12-28T23:59:59.000Z

    High resolution X-ray diffractometry (HR-XRD), Photoluminescence, Raman spectroscopy, and Transmission electron microscope measurements are reported for GaN deposited on a conventional Si(111) substrate and on the (111) facets etched on a Si(100) substrate. HR-XRD reciprocal space mappings showed that the GaN(0002) plane is tilted by about 0.63??0.02 away from the exposed Si(111) growth surface for GaN deposited on the patterned Si(100) substrate, while no observable tilt existed between the GaN(0002) and Si(111) planes for GaN deposited on the conventional Si(111) substrate. The ratio of integrated intensities of the yellow to near band edge (NBE) luminescence (I{sub YL}/I{sub NBE}) was determined to be about one order of magnitude lower in the case of GaN deposited on the patterned Si(100) substrate compared with GaN deposited on the conventional Si(111) substrate. The Raman E{sub 2}(high) optical phonon mode at 565.224??0.001?cm{sup ?1} with a narrow full width at half maximum of 1.526??0.002?cm{sup ?1} was measured, for GaN deposited on the patterned Si(100) indicating high material quality. GaN deposition within the trench etched on the Si(100) substrate occurred via diffusion and mass-transport limited mechanism. This resulted in a differential GaN layer thickness from the top (i.e., 1.8??m) of the trench to the bottom (i.e., 0.3??m) of the trench. Mixed-type dislocation constituted about 80% of the total dislocations in the GaN grown on the inclined Si(111) surface etched on Si(100)

  16. High-electron-mobility GaN grown on free-standing GaN templates by ammonia-based molecular beam epitaxy

    SciTech Connect (OSTI)

    Kyle, Erin C. H., E-mail: erinkyle@umail.ucsb.edu; Kaun, Stephen W.; Burke, Peter G.; Wu, Feng; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Wu, Yuh-Renn [Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, Taipei City 10617, Taiwan (China)

    2014-05-21T23:59:59.000Z

    The dependence of electron mobility on growth conditions and threading dislocation density (TDD) was studied for n{sup ?}-GaN layers grown by ammonia-based molecular beam epitaxy. Electron mobility was found to strongly depend on TDD, growth temperature, and Si-doping concentration. Temperature-dependent Hall data were fit to established transport and charge-balance equations. Dislocation scattering was analyzed over a wide range of TDDs (?2??10{sup 6}?cm{sup ?2} to ?2??10{sup 10}?cm{sup ?2}) on GaN films grown under similar conditions. A correlation between TDD and fitted acceptor states was observed, corresponding to an acceptor state for almost every c lattice translation along each threading dislocation. Optimized GaN growth on free-standing GaN templates with a low TDD (?2??10{sup 6}?cm{sup ?2}) resulted in electron mobilities of 1265 cm{sup 2}/Vs at 296?K and 3327 cm{sup 2}/Vs at 113?K.

  17. Micro-Raman and cathodoluminescence studies of epitaxial laterally overgrown GaN with tungsten masks: A method to map the free-carrier

    E-Print Network [OSTI]

    Nabben, Reinhard

    Micro-Raman and cathodoluminescence studies of epitaxial laterally overgrown GaN with tungsten properties of two epitaxial-laterally overgrown GaN structures with tungsten masks in 1100 and 1120 direction by tungsten masks3 to prevent the in-diffusion of silicon and oxygen atoms in the overgrown GaN, which

  18. GaN nanowire lasers with low lasing thresholds Silvija Gradecak, Fang Qian, Yat Li, Hong-Gyu Park, and Charles M. Liebera

    E-Print Network [OSTI]

    Li, Yat

    GaN nanowire lasers with low lasing thresholds Silvija Gradecak, Fang Qian, Yat Li, Hong-Gyu Park September 2005; published online 18 October 2005 We report optically pumped room-temperature lasing in GaN of 22 kW/cm2 that are substantially lower than other previously reported GaN nanowires. Key

  19. PHYSICAL REVIEW B VOLUME 52, NUMBER 23 15 DECEMBER 1995-I Properties of the yellow luminescence in undoped GaN epitaxial layers

    E-Print Network [OSTI]

    Nabben, Reinhard

    Micro-Raman and cathodoluminescence studies of epitaxial laterally overgrown GaN with tungsten masks: A method to map the free-carrier concentration of thick GaN samples A. Kaschner,a) A. Hoffmann properties of two epitaxial-laterally overgrown GaN structures with tungsten masks in 1100 and 1120 direction

  20. Impact of high-power stress on dynamic ON-resistance of high-voltage GaN HEMTs Donghyun Jin

    E-Print Network [OSTI]

    del Alamo, Jess A.

    Impact of high-power stress on dynamic ON-resistance of high-voltage GaN HEMTs Donghyun Jin-resistance (RON) in high- voltage GaN High-Electron-Mobility Transistors (HEMTs). We use a newly proposed dynamic. All rights reserved. 1. Introduction In the last decade, GaN Field-Effect Transistors have emerged

  1. GaN0.011P0.989GaP Double-Heterostructure Red Light-Emitting Diodes Directly Grown on GaP Substrates

    E-Print Network [OSTI]

    Tu, Charles W

    2000-01-01T23:59:59.000Z

    and C. W. Tu, GaN diodes on GaP substrates, 2000. [7] J. W.on a GaN directly grown on a GaP substrate was successfullyDH) directly a GaN grown on a (100) GaP substrate. Fig. 1(a)

  2. The influence of substrate surface preparation on LP MOVPE GaN epitaxy on differently oriented 4H-SiC substrates

    E-Print Network [OSTI]

    Ozbay, Ekmel

    The influence of substrate surface preparation on LP MOVPE GaN epitaxy on differently oriented 4H preparation and off-cut of 4H-SiC substrates on morphological and structural properties of GaN grown by low-SiC is most suitable for GaN epitaxy and that substrate etching improves the surface morphology of epilayer

  3. Growth of GaN on SiC(0001) by Molecular Beam Epitaxy C. D. LEE (a), ASHUTOSH SAGAR (a), R. M. FEENSTRA

    E-Print Network [OSTI]

    Feenstra, Randall

    years as a substrate for both molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy of GaN of the substrate preparation and growth technique. Experimental GaN films of typically 1 mm thickness are deposited1 Growth of GaN on SiC(0001) by Molecular Beam Epitaxy C. D. LEE (a), ASHUTOSH SAGAR (a), R. M

  4. Effect of dislocation scattering on the transport properties of InN grown on GaN substrates by molecular beam epitaxy

    E-Print Network [OSTI]

    Effect of dislocation scattering on the transport properties of InN grown on GaN substrates on GaN substrates by plasma-assisted molecular beam epitaxy. They have found a strong correlation, optical, and transport properties of InN on GaN substrates. In this work, we have studied the MBE growth

  5. Supporting Document Strategic Plan

    E-Print Network [OSTI]

    Auckland, University of

    1 Supporting Document Strategic Plan 20132020 #12;2 Supporting Document Strategic Plan 2013 more critical to the University's future than was the case in 2005. The purpose of this document are summarised via a SWOT analysis in Appendix 1. This document should therefore be read in conjunction

  6. 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.

  7. Optically active centers in Eu implanted, Eu in situ doped GaN, and Eu doped GaN quantum dots

    SciTech Connect (OSTI)

    Bodiou, L.; Braud, A.; Doualan, J.-L.; Moncorge, R. [Centre de Recherche sur les Ions, les Materiaux et la Photonique (CIMAP), CNRS-CEA-ENSICAEN, Universite de Caen, UMR 6252, 14050 Caen (France); Park, J. H.; Munasinghe, C.; Steckl, A. J. [University of Cincinnati, Cincinnati, Ohio 45221-0030 (United States); Lorenz, K.; Alves, E. [Instituto Tecnologico e Nuclear, Estrada Nacional 10, PT-2685-953 Sacavem (Portugal); Daudin, B. [INAC SP2M/PSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2009-02-15T23:59:59.000Z

    A comparison is presented between Eu implanted and Eu in situ doped GaN thin films showing that two predominant Eu sites are optically active around 620 nm in both types of samples with below and above bandgap excitation. One of these sites, identified as a Ga substitutional site, is common to both types of Eu doped GaN samples despite the difference in the GaN film growth method and in the doping technique. High-resolution photoluminescence (PL) spectra under resonant excitation reveal that in all samples these two host-sensitized sites are in small amount compared to the majority of Eu ions which occupy isolated Ga substitutional sites and thus cannot be excited through the GaN host. The relative concentrations of the two predominant host-sensitized Eu sites are strongly affected by the annealing temperature for Eu implanted samples and by the group III element time opening in the molecular beam epitaxy growth. Red luminescence decay characteristics for the two Eu sites reveal different excitation paths. PL dynamics under above bandgap excitation indicate that Eu ions occupying a Ga substitutional site are either excited directly into the {sup 5}D{sub 0} level or into higher excited levels such as {sup 5}D{sub 1}, while Eu ions sitting in the other site are only directly excited into the {sup 5}D{sub 0} level. These differences are discussed in terms of the spectral overlap between the emission band of a nearby bound exciton and the absorption bands of Eu ions. The study of Eu doped GaN quantum dots reveals the existence of only one type of Eu site under above bandgap excitation, with Eu PL dynamics features similar to Eu ions in Ga substitutional sites.

  8. Thermoelectric effects in wurtzite GaN and AlxGa1-xN alloys and Alexander A. Balandin

    E-Print Network [OSTI]

    with the active thermoelectric cooling implemented on the same material system can improve the device performance, for the pro- posed cooling system should also be based on GaN. To real- ize this, the high-efficiency Ga,6 Great progress has been achieved in GaN-based microwave technology. GaN transistors with very high

  9. First-principles studies of beryllium doping of GaN Chris G. Van de Walle* and Sukit Limpijumnong

    E-Print Network [OSTI]

    First-principles studies of beryllium doping of GaN Chris G. Van de Walle* and Sukit Limpijumnong Received 12 October 2000; published 8 June 2001 The structural and electronic properties of beryllium acceptors, and between hydrogen and substitutional beryllium. The results for wurtzite GaN are compared

  10. Reconstructions of GaN,,0001... and ,,0001... surfaces: Ga-rich metallic A. R. Smith and R. M. Feenstraa)

    E-Print Network [OSTI]

    wurtzite material.19 A common theme regarding the growth of these surfaces in the absence of hydrogen and elec- tronic properties of two reconstructions for wurtzite GaN: the 1 1 structure of the GaN 0001

  11. PHYSICAL REVIEW B 86, 075207 (2012) Optical signature of Mg-doped GaN: Transfer processes

    E-Print Network [OSTI]

    Nabben, Reinhard

    2012-01-01T23:59:59.000Z

    PHYSICAL REVIEW B 86, 075207 (2012) Optical signature of Mg-doped GaN: Transfer processes G; published 23 August 2012) Mg doping of high quality, metal organic chemical vapor deposition grown GaN films GaN:Mg grown on sapphire substrates and identify two Mg related acceptor states, one additional

  12. Belgirate, Italy, 28-30 September 2005 THERMAL MODELLING OF MULTI-FINGER ALGAN/GAN HEMT's

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    Belgium contact author: herman.oprins@imec.be ABSTRACT AlGaN/GaN high electron mobility transistors (HEMTs validation of the modelling, both structures are thermally optimized. 1. INTRODUCTION As GaN devices operate of delivering about 0.75W/mm. The rapid increase in power density since the beginning of the development of GaN

  13. Luminescence Efficiency of InGaN/GaN Quantum Wells on Bulk GaN Substrate M. Dworzak1

    E-Print Network [OSTI]

    Nabben, Reinhard

    Luminescence Efficiency of InGaN/GaN Quantum Wells on Bulk GaN Substrate M. Dworzak1 , T. Stempel1/37, 01-142 Warsaw, Poland ABSTRACT Time-integrated and time-resolved photoluminescence measurements on InGaN quantum wells grown by MOCVD on two different substrates (sapphire and GaN) show that the lumines- cence

  14. Effect of Trapping on the Critical Voltage for Degradation in GaN High Electron Mobility Transistors

    E-Print Network [OSTI]

    del Alamo, Jess A.

    power and high frequency applications. Si is an attractive substrate for GaN HEMTs because of its lower and thermal mismatch between GaN and Si as compared to the more commonly used substrate, SiC, results in more regardless of the characteristics of the substrate. II. EXPERIMENTAL We studied experimental AlxGa1xN/GaN

  15. The Effect of Periodic Silane Burst on the Properties of GaN on Si (111) Substrates

    E-Print Network [OSTI]

    Zang, Keyan

    The periodic silane burst technique was employed during metalorganic chemical vapor deposition of epitaxial GaN on AlN buffer layers grown on Si (111). Periodic silicon delta doping during growth of both the AlN and GaN ...

  16. Tuning linear and nonlinear optical properties of wurtzite GaN by c-axial stress

    E-Print Network [OSTI]

    Cai, Duanjun; 10.1088/0022-3727/42/18/185107

    2009-01-01T23:59:59.000Z

    We study the linear and nonlinear optical properties of wurtzite GaN under c-axial stress field, using density functional theory calculations. The fully structural optimization at each c-axial strain was performed. The calculated dielectric functions show that tensile c-axial strain effectively improves the linear optical efficiency, especially for the band-edge transitions, and significantly increase the mobility of electrons in the conduction band. Second-order nonlinear optical susceptibilities show that the tensile c-axial strain will enhance the zero- and low-frequency nonlinear responses of GaN. The enhancement of the nonlinear optical property is explained by the reduction of the polarization of wurtzite GaN under tensile c-axial strains. Based on these findings, we propose a method for improving the electrical and optical properties of the crystal through imposing appropriate stress on the high symmetry crystalline directions.

  17. Electrical characterization of ensemble of GaN nanowires grown by the molecular beam epitaxy technique

    SciTech Connect (OSTI)

    Kolkovsky, Vl. [Technische Universitt Dresden, 01062 Dresden (Germany)] [Technische Universitt Dresden, 01062 Dresden (Germany); Zytkiewicz, Z. R.; Sobanska, M.; Klosek, K. [Institute of Physics Polish Academy of Sciences, Al. Lotnikow 32-46, 02-668 Warsaw (Poland)] [Institute of Physics Polish Academy of Sciences, Al. Lotnikow 32-46, 02-668 Warsaw (Poland)

    2013-08-26T23:59:59.000Z

    High quality Schottky contacts are formed on GaN nanowires (NWs) structures grown by the molecular beam epitaxy technique on Si(111) substrate. The current-voltage characteristics show the rectification ratio of about 10{sup 3} and the leakage current of about 10{sup ?4} A/cm{sup 2} at room temperature. From the capacitance-voltage measurements the free carrier concentration in GaN NWs is determined as about 10{sup 16} cm{sup ?3}. Two deep levels (H200 and E280) are found in the structures containing GaN NWs. H200 is attributed to an extended defect located at the interface between the substrate and SiN{sub x} or near the sidewalls at the bottom of the NWs whereas E280 is tentatively assigned to a gallium-vacancy- or nitrogen interstitials-related defect.

  18. Synthesis, morphology and optical properties of GaN and AlGaN semiconductor nanostructures

    SciTech Connect (OSTI)

    Kuppulingam, B., E-mail: drbaskar2009@gmail.com; Singh, Shubra, E-mail: drbaskar2009@gmail.com; Baskar, K., E-mail: drbaskar2009@gmail.com [Crystal Growth Centre, Anna University, Chennai-600025 (India)

    2014-04-24T23:59:59.000Z

    Hexagonal Gallium Nitride (GaN) and Aluminum Gallium Nitride (AlGaN) nanoparticles were synthesized by sol-gel method using Ethylene Diamine Tetra Acetic acid (EDTA) complex route. Powder X-ray diffraction (PXRD) analysis confirms the hexagonal wurtzite structure of GaN and Al{sub 0.25}Ga{sub 0.75}N nanoparticles. Surface morphology and elemental analysis were carried out by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX). The room temperature Photoluminescence (PL) study shows the near band edge emission for GaN at 3.35 eV and at 3.59 eV for AlGaN nanoparticles. The Aluminum (Al) composition of 20% has been obtained from PL emission around 345 nm.

  19. Interaction of hydrogen with gallium vacancies in wurtzite GaN

    SciTech Connect (OSTI)

    Wright, A. F.

    2001-08-01T23:59:59.000Z

    First-principles techniques are used to investigate the interaction of hydrogen with gallium vacancies in wurtzite GaN. The calculations reveal that hydrogen can either compensate a vacancy by donating an electron to a vacancy acceptor level, or passivate the vacancy by forming a hydrogen-vacancy complex. A gallium vacancy can bind up to four hydrogen atoms, and hydrogen removal energies are computed as a function of the number of hydrogen atoms. Removal energies are found to depend strongly on Fermi level and complexes containing more than two hydrogen atoms are predicted to be unstable in n-type GaN. Hydrogen vibration frequencies are computed and compared with previously reported infrared absorption measurements for hydrogen-implanted GaN.

  20. Long-Lived, Coherent Acoustic Phonon Oscillations in GaN Single Crystals

    SciTech Connect (OSTI)

    Wu, S.; Geiser, P.; Jun, J.; Karpinski, J.; Park, J.-R.; Sobolewski, R.

    2006-01-31T23:59:59.000Z

    We report on coherent acoustic phonon (CAP) oscillations studied in high-quality bulk GaN single crystals with a two-color femtosecond optical pump-probe technique. Using a far-above-the-band gap ultraviolet excitation (~270 nm wavelength) and a near-infrared probe beam (~810 nm wavelength), the long-lived, CAP transients were observed within a 10 ns time-delay window between the pump and probe pulses, with a dispersionless (proportional to the probe-beam wave vector) frequency of ~45 GHz. The measured CAP attenuation corresponded directly to the absorption of the probe light in bulk GaN, indicating that the actual (intrinsic) phonon-wave attenuation in our crystals was significantly smaller than the measured 65.8 cm^-1 value. The velocity of the phonon propagation was equal to the velocity of sound in GaN.

  1. Effect of buffer layer growth temperature on epitaxial GaN films deposited by magnetron sputtering

    SciTech Connect (OSTI)

    Mohanta, P.; Singh, D.; Kumar, R.; Ganguli, T.; Srinivasa, R. S.; Major, S. S. [Center For Research in Nano-Technology and Science (India); Semiconductor Laser Section, RRCAT, Indore-452013 (India); Department of Metallurgical Engineering and Materials Science (India); Department of Physics, Indian Institute of Technology Bombay, Mumbai - 400076 (India)

    2012-06-05T23:59:59.000Z

    Epitaxial GaN films were deposited by reactive sputtering of a GaAs target in 100 % nitrogen at 700 deg. C on ZnO buffer layers grown at different substrate temperatures over sapphire substrates. High resolution X-ray diffraction measurements and the corresponding analysis show that the growth temperature of buffer layers significantly affects the micro-structural parameters of GaN epilayer, such as lateral coherence length, tilt and twist, while the vertical coherence length remains unaffected. The optimum substrate temperature for buffer layer growth has been found to be 300 deg. C. High epitaxial quality GaN film grown on such a buffer layer exhibited micro strain of 1.8x10{sup -4} along with screw and edge type dislocation densities of 7.87x10{sup 9} and 1.16x10{sup 11}, respectively.

  2. Evidence of satellite valley position in GaN by photoexcited field emission spectroscopy

    SciTech Connect (OSTI)

    Yilmazoglu, O.; Pavlidis, D.; Hartnagel, H. L. [Department of High Frequency Electronics, Technische Universitaet Darmstadt, 64283 Darmstadt (Germany); Evtukh, A.; Litovchenko, V.; Semenenko, N. [Institute of Semiconductor Physics, NASU, 03028 Kiev (Ukraine)

    2008-06-01T23:59:59.000Z

    GaN field emitter rods with nanometer diameter were fabricated by photoelectrochemical etching on a n{sup +}-GaN substrate. Their electron field emission properties were investigated under ultraviolet (UV) illumination. The Fowler-Nordheim plots of the emission current show different slopes for nonilluminated and UV illuminated devices. A model based on the electron emission from valleys having different specific electron affinities is proposed to explain the experimental results. In the absence of illumination, the GaN rods are almost fully depleted and emission takes place only from the lower valley. Upon UV illumination and presence of a high electric field at the emitter tip, the upper valley of the conduction band appears to be occupied by electrons generated at the valence band. The energy difference between the lower and upper valleys was determined to be 1.15 eV and is in good agreement with formerly published theoretical and measured values.

  3. Prarie View RDF

    Energy Savers [EERE]

    PRAIRIE VIEW RDF 2 Prairie View RDF Located at JAAP (approx. 40 miles southwest of Chicago), 223 acres on 455 Acre Parcel Will County Owner; Waste Management, Operator ...

  4. Design and Experimental Characterization of an Erbium Doped GaN Waveguide

    E-Print Network [OSTI]

    Wang, Qian

    2012-05-31T23:59:59.000Z

    temperatures as compared to other semiconductor host materials such as Si and GaAs. 1540nm optical emission in Er- doped waveguide has also been demonstrated using a 365nm light emitting diode as the optical pumping source. UV pumping above the GaN bandgap....9 eV In Table 2 - 1, GaN is the semiconductor material with the largest bandgap (SiO2 is not a semiconductor), which has proven to be an accomplished host of erbium, with reports of fabrication of light- emitting diodes operating in the visible...

  5. X-ray detectors based on GaN Schottky diodes

    SciTech Connect (OSTI)

    Duboz, Jean-Yves; Frayssinet, Eric; Chenot, Sebastien [CRHEA, CNRS, Rue Bernard Gregory, Sophia Antipolis, F-06560 Valbonne (France); Reverchon, Jean-Luc [THALES R and T, Campus Polytechnique, 1 avenue Augustin Fresnel, F-91767 Palaiseau Cedex (France); Idir, Mourad [Synchrotron SOLEIL L'Orme des Merisiers, Saint-Aubin-BP 48 91192, GIF-sur-Yvette Cedex (France)

    2010-10-18T23:59:59.000Z

    GaN Schottky diodes have been fabricated and tested as x-ray detectors in the range from 6 to 21 keV. The spectral response has been measured and is compared to its theoretical value. The study of the response and its temporal dynamics as a function of the bias allows to identify a photovoltaic behavior at low bias and a photoconductive one at larger reverse biases. The GaN diode turned out to be linear as a function of the incident power. The noise and detectivity are given and discussed.

  6. Characterization of GaN microstructures grown by plasma-assisted molecular beam epitaxy

    SciTech Connect (OSTI)

    Lo, Ikai; Pang, Wen-Yuan; Hsu, Yu-Chi; Hsieh, Chia-Ho; Shih, Cheng-Hung; Chou, Mitch M. C. [Department of Physics and Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Chen, Wen-Yen; Hsu, Tzu-Min [Department of Physics, National Central University, Jhong-li, Taoyuan 32001, Taiwan (China); Hsu, Gary Z. L. [United Crystal Corporation, No.243-3, Wenshan, 36061, Miaoli, Taiwan (China)

    2013-06-15T23:59:59.000Z

    The characterization of GaN microstructures grown by plasma-assisted molecular beam epitaxy on LiAlO{sub 2} substrate was studied by cathodoluminescence and photoluminescence measurements. We demonstrated that the cathodoluminescence from oblique semi-polar surfaces of mushroom-shaped GaN was much brighter than that from top polar surface due to the reduction of polarization field on the oblique semi-polar surfaces. It implies that the oblique semi-polar surface is superior for the light-emitting surface of wurtzite nano-devices.

  7. Ge doped GaN with controllable high carrier concentration for plasmonic applications

    SciTech Connect (OSTI)

    Kirste, Ronny; Hoffmann, Marc P.; Sachet, Edward; Bobea, Milena; Bryan, Zachary; Bryan, Isaac; Maria, Jon-Paul; Collazo, Ramn; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)] [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States); Nenstiel, Christian; Hoffmann, Axel [Institut f?r Festkrperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)] [Institut f?r Festkrperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2013-12-09T23:59:59.000Z

    Controllable Ge doping in GaN is demonstrated for carrier concentrations of up to 2.4??10{sup 20} cm{sup ?3}. Low temperature luminescence spectra from the highly doped samples reveal band gap renormalization and band filling (Burstein-Moss shift) in addition to a sharp transition. Infrared ellipsometry spectra demonstrate the existence of electron plasma with an energy around 3500?cm{sup ?1} and a surface plasma with an energy around 2000?cm{sup ?1}. These findings open possibilities for the application of highly doped GaN for plasmonic devices.

  8. Partially filled intermediate band of Cr-doped GaN films

    SciTech Connect (OSTI)

    Sonoda, S. [Department of Electronics, Kyoto Institute of Technology, Kyoto 606-8585 (Japan)

    2012-05-14T23:59:59.000Z

    We investigated the band structure of sputtered Cr-doped GaN (GaCrN) films using optical absorption, photoelectron yield spectroscopy, and charge transport measurements. It was found that an additional energy band is formed in the intrinsic band gap of GaN upon Cr doping, and that charge carriers in the material move in the inserted band. Prototype solar cells showed enhanced short circuit current and open circuit voltage in the n-GaN/GaCrN/p-GaN structure compared to the GaCrN/p-GaN structure, which validates the proposed concept of an intermediate-band solar cell.

  9. Extraction of absorption coefficients from GaN nanowires grown on opaque substrates

    E-Print Network [OSTI]

    Jayaprakash, Rahul; Germanis, Savvas; Androulidaki, Maria; Tsagaraki, Katerina; Georgakilas, Alexandros; Pelekanos, Nikos T

    2014-01-01T23:59:59.000Z

    We demonstrate a new method to measure absorption coefficients in any family of nanowires, provided they are grown on a substrate having considerable difference in permittivity with the nanowire-air matrix. In the case of high crystal quality, strain-free GaN nanowires, grown on Si (111) substrates with a density of ~1010 cm-2, the extracted absorption coefficients do not exhibit any enhancement compared to bulk GaN values, unlike relevant claims in the literature. This may be attributed to the relatively small diameters, short heights, and high densities of our nanowire arrays.

  10. Realization of compressively strained GaN films grown on Si(110) substrates by inserting a thin AlN/GaN superlattice interlayer

    SciTech Connect (OSTI)

    Shen, X. Q.; Takahashi, T.; Kawashima, H.; Ide, T.; Shimizu, M. [Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-1, Central 2, Tsukuba-shi, Ibaraki 305-8568 (Japan)

    2012-07-16T23:59:59.000Z

    We investigate the strain properties of GaN films grown by plasma-assisted molecular beam epitaxy on Si(110) substrates. It is found that the strain of the GaN film can be converted from a tensile to a compressive state simply by inserting a thin AlN/GaN superlattice structure (SLs) within the GaN film. The GaN layers seperated by the SLs can have different strain states, which indicates that the SLs plays a key role in the strain modulation during the growth and the cooling down processes. Using this simple technique, we grow a crack-free GaN film exceeding 2-{mu}m-thick. The realization of the compressively strained GaN film makes it possible to grow thick GaN films without crack generation on Si substrates for optic and electronic device applications.

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  18. Acceptable NSLS Safety Documentation

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  19. GTT Tranmission Workshop- Documents

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  20. Classification Documents and Publications

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  1. In this document: Freshmanadmissiondecisionoverview

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  3. Office Automation Document Preparation

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  5. Spectroscopic and magnetic properties of Mn doped GaN epitaxial films grown by plasma assisted molecular beam epitaxy

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    Vidyasagar, R., E-mail: dr.vidyasagar1979@gmail.com [Department of Physics and Centre for Nanoscience and Nanotechnology, National Sun-Yat Sen University, Kaohsiung 80424, Taiwan, ROC (China); Lin, Y.-T.; Tu, L.-W. [Department of Physics and Centre for Nanoscience and Nanotechnology, National Sun-Yat Sen University, Kaohsiung 80424, Taiwan, ROC (China)] [Department of Physics and Centre for Nanoscience and Nanotechnology, National Sun-Yat Sen University, Kaohsiung 80424, Taiwan, ROC (China)

    2012-12-15T23:59:59.000Z

    Graphical abstract: We report here that micro-Raman scattering spectrum for Mn doped GaN thin film has displayed a new peak manifested at 578 cm{sup ?1}, by which it is attributed to interior LVM originated by the incorporation of Mn ions in place of Ga sites. Mn doped GaN thin film also showed the typical negative magnetoresistance up to ?50 K, revealing that the film showed magnetic ordering of spins below 50 K. Display Omitted Highlights: ? GaN and Mn doped GaN single phase wurtzite structures grown by PAMBE. ? The phase purity of the epilayers investigated by HRXRD, HRSEM and EDX. ? The red shift in near band edge emission has been observed using micro-PL. ? A new peak related LVM at 578 cm{sup ?1} in micro-Raman scattering measurements confirmed Mn doped into GaN. ? Negative-magnetoresistance investigations have showed that the film has T{sub c} < 50 K. -- Abstract: Spectroscopic and magnetic properties of Mn doped GaN, and GaN epitaxial films have been investigated by employing micro-photoluminescence, micro-Raman, and temperature dependent magneto-resistance measurements. The HR-XRD profiles have shown that the epitaxial films are in hexagonal wurtzite structures. Morphology and composition of the films have been examined by field emission scanning electron microscopy, and energy-dispersive X-ray analysis. Micro-photoluminescence spectrum displayed a dominant near band edge emission at 362 nm, which is assigned to near band edge transition within the hexagonal structure of GaN. Raman scattering profiles showed a new vibrational mode at 578 cm{sup ?1}, which is attributed to the vacancy-related local vibrational mode of Mn occupying the Ga site. Temperature dependent negative magnetoresistance measurements provide a direct evidence of magnetic ordering below 50 K for the Mn doped GaN thin film.

  6. Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes

    SciTech Connect (OSTI)

    Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)] [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

    2013-01-28T23:59:59.000Z

    We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

  7. Low frequency noise in GaN metal semiconductor and metal oxide semiconductor field effect transistors

    E-Print Network [OSTI]

    Pala, Nezih

    , and Systems Engineering and Center for Integrated Electronics and Electronics Manufacturing, CII 9017, University of South Carolina, Columbia, South Carolina 29208 Received 22 January 2001; accepted American Institute of Physics. DOI: 10.1063/1.1372364 I. INTRODUCTION A recent report on GaN highly doped

  8. Performance degradation of GaN field-effect transistors due to thermal

    E-Print Network [OSTI]

    . We used the standard model for the band gap energy temperature dependence EG EG0 aT2 =(b material specific models for carrier drift-diffusion and thermal conductivity the authors deter- mine in GaN transis- tors is also discussed. Obtained results can be used for structure optimisation of Ga

  9. Atomic-scale studies on the growth of palladium and titanium on GaN(0001)

    E-Print Network [OSTI]

    Castell, Martin

    Atomic-scale studies on the growth of palladium and titanium on GaN(0001) C. Norenberg a,b,*, M nitride; Palladium; Titanium; Alloys; Epitaxy; Metalsemiconductor interfaces; Nanostructures; Scanning;Here, we have focused on atomic-scale studies of the ini- tial growth stages of palladium and titanium

  10. FOURIER COEFFICIENTS OF MODULAR FORMS ON G2 WEE TECK GAN, BENEDICT GROSS AND GORDAN SAVIN

    E-Print Network [OSTI]

    Gan, Wee Teck

    FOURIER COEFFICIENTS OF MODULAR FORMS ON G2 WEE TECK GAN, BENEDICT GROSS AND GORDAN SAVIN Abstract. We develop a theory of Fourier coefficients for modular forms on the split ex- ceptional group G2 on the group SL2(Z) is the wealth of information carried by the Fourier coefficients an(f), for n 0

  11. Lattice Protein Folding With Two and Four-Body Statistical Hin Hark Gan,1

    E-Print Network [OSTI]

    Schlick, Tamar

    Lattice Protein Folding With Two and Four-Body Statistical Potentials Hin Hark Gan,1 Alexander/sequence compatibility of proteins,5,6 homology modeling,7 and protein folding simulations.8 10 Currently, most structures. Multibody potentials may help improve our understanding of the cooperativity of protein folding

  12. High-Efficiency X-Band MMIC GaN Power Amplifiers Operating as Rectifiers

    E-Print Network [OSTI]

    Popovic, Zoya

    High-Efficiency X-Band MMIC GaN Power Amplifiers Operating as Rectifiers Michael Litchfield, Scott two 10 x 100j.Lm power combined devices. The MMICs exhibit 67% and 56% power added efficiency at VDD a RF-to-DC efficiency of 64%. The output powers of the two MMIC PAs are around 3.2W. In rectifier mode

  13. GaN Based Nanomaterials Fabrication with Anodic Aluminium Oxide by MOCVD

    E-Print Network [OSTI]

    Wang, Yadong

    A highly self-ordered hexagonal array of cylindrical pores has been fabricated by anodizing a thin film of Al on substrate and subsequent growth of GaN and InGaN in these nanoholes has been performed. This AAO template-based ...

  14. Lifetime estimation of intrinsic silicon nitride MIM capacitors in a gan MMIC process

    E-Print Network [OSTI]

    Demirtas, Sefa

    We have studied the reliability of intrinsic SiN MIM capacitors designed for 48 V and 125 [superscript 0]C operation and manufactured in a GaN process flow. It is shown that very small area capacitors (10um x 10um) with a ...

  15. Fine structure of the red luminescence band in undoped GaN

    SciTech Connect (OSTI)

    Reshchikov, M. A., E-mail: mreshchi@vcu.edu [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Usikov, A. [Nitride Crystals, Inc., 181E Industry Ct., Ste. B, Deer Park, New York 11729 (United States); Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49 Kronverkskiy Ave., 197101 Saint Petersburg (Russian Federation); Helava, H.; Makarov, Yu. [Nitride Crystals, Inc., 181E Industry Ct., Ste. B, Deer Park, New York 11729 (United States)

    2014-01-20T23:59:59.000Z

    Many point defects in GaN responsible for broad photoluminescence (PL) bands remain unidentified. Their presence in thick GaN layers grown by hydride vapor phase epitaxy (HVPE) detrimentally affects the material quality and may hinder the use of GaN in high-power electronic devices. One of the main PL bands in HVPE-grown GaN is the red luminescence (RL) band with a maximum at 1.8?eV. We observed the fine structure of this band with a zero-phonon line (ZPL) at 2.36?eV, which may help to identify the related defect. The shift of the ZPL with excitation intensity and the temperature-related transformation of the RL band fine structure indicate that the RL band is caused by transitions from a shallow donor (at low temperature) or from the conduction band (above 50?K) to an unknown deep acceptor having an energy level 1.130?eV above the valence band.

  16. Electron Beam-induced Light Emission and Transport in GaN Nanowires

    SciTech Connect (OSTI)

    Tringe, J W; MoberlyChan, W J; Stevens, C G; Davydov, A V; Motayed, A

    2006-05-10T23:59:59.000Z

    We report observations of electron beam-induced light from GaN nanowires grown by chemical vapor deposition. GaN nanowires were modified in-situ with deposited opaque platinum coatings to estimate the extent to which light is channeled to the ends of nanowires. Some evidence of light channeling was found, but wire microstructure and defects play an important role in light scattering and transport, limiting the extent to which light is confined. Optical interconnects are powerful components presently applied for high bandwidth communications among high-performance processors. Future circuits based on nanometer-scale components could similarly benefit from optical information transfer among processing blocks. Strong light channeling (and even lasing) has been observed in GaN nanowires, suggesting that these structures could be useful building blocks in a future networked electro-optical processor. However, the extent to which defects and microstructure control optical performance in nanowire waveguides has not been measured. In this study, we use electron microscopy and in-situ modification of individual nanowires to begin to correlate wire structure with light transport efficiency through GaN nanowires tens of microns long.

  17. Anomalous photoresponse of GaN x-ray Schottky detectors

    SciTech Connect (OSTI)

    Duboz, Jean-Yves [CRHEA, CNRS, rue Bernard Gregory, Sophia Antipolis, F-06560 Valbonne (France); Beaumont, Bernard [Lumilog Groupe Saint GOBAIN Crystals, 2720 Chemin de Saint Bernard, F-06220 Vallauris (France); Reverchon, Jean-Luc [THALES R and T, Campus Polytechnique, 1 Avenue Augustin Fresnel, F-91767 Palaiseau Cedex (France); Wieck, Andreas D. [Fakultaet fuer Physik und Astronomie, Lehrstuhl fuer Angewandte Festkoerperphysik, D-44780 Bochum (Germany)

    2009-06-01T23:59:59.000Z

    GaN based materials are believed to be very stable materials, in particular, under irradiation by high energy photons such as x rays. We have studied x-ray detectors based on GaN Schottky diodes. Vertical Schottky diodes were fabricated based on a 20 mum thick undoped GaN layer grown on a conductive GaN substrate. Their photoresponse to near UV light and to x rays was measured. While the response to near UV light was fast and linear as expected, anomalous behaviors were observed under x-ray illumination. The photocurrent increases as the third power of the incident x-ray flux. The photocurrent transient when the x rays is turned on are long and nonexponential (S shape) and strongly differs from the off transient which is fast and exponential. Also, a very strong quenching of the x-ray photoresponse is observed when the detector is simultaneously illuminated with visible light. All of these anomalous behaviors are explained in the frame of a complete model involving traps and tunnel currents. A reasonable quantitative agreement between the model and the experimental data is obtained.

  18. 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.

  19. Critical Voltage for Electrical Reliability of GaN High Electron Mobility Transistors on Si Substrate

    E-Print Network [OSTI]

    Demirtas, Sefa

    We have evaluated the electrical reliability of GaN HEMTs on Si by carrying out V[subscript DS] = 0 V step-stress experiments. We have found that these devices show a degradation pattern that is very similar to that of ...

  20. The Growth of GaN on Si by the Beam Flux Modulation

    SciTech Connect (OSTI)

    Roh, C. H.; Ha, M. W.; Song, H. J.; Choi, H. G.; Lee, J. H.; Ra, Y. W.; Hahn, C. K. [Compound Semiconductor Devices Research Center, Energy-Display R and D Division, Korea Electronics Technology Institute, Seongnam (Korea, Republic of)

    2011-12-23T23:59:59.000Z

    AlGaN/GaN HEMT structure was grown on Si (111) substrate by plasma-assisted molecular beam epitaxy (PA-MBE) using a beam flux modulation methods. In this result, it was verified that the propagation of treading dislocation (TD) due to N-rich GaN layer was effectively suppressed.

  1. High Efficiency m-plane LEDs on Low Defect Density Bulk GaN Substrates

    SciTech Connect (OSTI)

    David, Aurelien

    2012-10-15T23:59:59.000Z

    Solid-state lighting is a key technology for reduction of energy consumption in the US and worldwide. In principle, by replacing standard incandescent bulbs and other light sources with sources based on light-emitting diodes (LEDs), ultimate energy efficiency can be achieved. The efficiency of LEDs has improved tremendously over the past two decades, however further progress is required for solid- state lighting to reach its full potential. The ability of an LED at converting electricity to light is quantified by its internal quantum efficiency (IQE). The material of choice for visible LEDs is Gallium Nitride (GaN), which is at the basis of blue-emitting LEDs. A key factor limiting the performance of GaN LEDs is the so-called efficiency droop, whereby the IQE of the LED decreases significantly at high current density. Despite decades of research, efficiency droop remains a major issue. Since high-current operation is necessary for practical lighting applications, reducing droop is a major challenge for the scientific community and the LED industry. Our approach to solving the droop issue is the use of newly available low-defect-density bulk GaN non-polar substrates. In contrast to the standard foreign substrates (sapphire, silicon carbide, silicon) used in the industry, we have employed native bulk GaN substrates with very low defect density, thus ensuring exquisite material quality and high IQE. Whereas all commercial LEDs are grown along the c-plane crystal direction of GaN, we have used m-plane non-polar substrates; these drastically modify the physical properties of the LED and enable a reduction of droop. With this approach, we have demonstrated very high IQE performance and low droop. Our results focused on violet and blue LEDs. For these, we have demonstrated very high peak IQEs and current droops of 6% and 10% respectively (up to a high current density of 200A.cm-2). All these results were obtained under electrical operation. These high IQE and low droop values are in line with the programs milestones. They demonstrate that bulk non-polar GaN substrates represent a disruptive technology for LED performance. Application of this technology to real-world products is feasible, provided that the cost of GaN substrates is compatible with the markets requirement.

  2. Ultra High p-doping Material Research for GaN Based Light Emitters

    SciTech Connect (OSTI)

    Vladimir Dmitriev

    2007-06-30T23:59:59.000Z

    The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading in light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing better understanding of p-type GaN formation for Solid State Lighting community. Grown p-type GaN layers were used as substrates for blue and green InGaN-based LEDs made by HVPE technology at TDI. These results proved proposed technical approach and facilitate fabrication of highly conductive p-GaN materials by low-cost HVPE technology for solid state lighting applications. TDI has started the commercialization of p-GaN epitaxial materials.

  3. Ab initio density functional theory study of non-polar (101{sup }0),?(112{sup }0) and semipolar (202{sup }1) GaN surfaces

    SciTech Connect (OSTI)

    Mutombo, P.; Romanyuk, O., E-mail: romanyuk@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnick 10, 16200 Prague (Czech Republic)

    2014-05-28T23:59:59.000Z

    The atomic structures of non-polar GaN(101{sup }0),?(112{sup }0) and semipolar GaN(202{sup }1),?(202{sup }1{sup }) surfaces were studied using ab initio calculations within density functional theory. The bulk-like truncated (1??1) structure with buckled Ga-N or Ga-Ga dimers was found stable on the non-polar GaN(101{sup }0) surface in agreement with previous works. Ga-N heterodimers were found energetically stable on the GaN(112{sup }0)-(1??1) surface. The formation of vacancies and substitution site defects was found unfavorable for non-polar GaN surfaces. Semipolar GaN(202{sup }1)-(1??1) surface unit cells consist of non-polar (101{sup }0) and semipolar (101{sup }1) nano-facets. The (101{sup }1) nano-facets consist of two-fold coordinated atoms, which form N-N dimers within a (2??1) surface unit cell on a GaN(202{sup }1) surface. Dimers are not formed on the GaN(202{sup }1{sup }) surface. The stability of the surfaces with single (101{sup }0) or (101{sup }1) nano-facets was analyzed. A single non-polar (101{sup }0)-(1??1) nano-facet was found stable on the GaN(202{sup }1) surface, but unstable on the GaN(202{sup }1{sup }) surface. A single (101{sup }1) nano-facet was found unstable. Semipolar GaN surfaces with (202{sup }1) and (202{sup }1{sup }) polarity can be stabilized with a Ga overlayer at Ga-rich experimental conditions.

  4. Appendix 3 Document Scanning Guidelines Appendix 3 Document Scanning Guidelines

    E-Print Network [OSTI]

    Tsien, Roger Y.

    Appendix 3 Document Scanning Guidelines App.3-1 Appendix 3 Document Scanning Guidelines 1. Turn. Note: Whenever possible, it is best to convert a Word document into a PDF than to scan a document and convert it to a PDF. A Word document that has been converted is searchable; a scanned document is not. 2

  5. UNCLASSIFIHED DEFENSE DOCUMENTATION CENTER

    E-Print Network [OSTI]

    Block, Marco

    UNCLASSIFIHED AD 463473 DEFENSE DOCUMENTATION CENTER FOR SCIENTIFIC AND TECHNICAL INFORMATION .... John Barton Head OR Analysis Group R. H. Krolick Manager Applied Science Laboratory Prepared for the .J

  6. Geothermal: Hot Documents Search

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

    Hot Documents Search Geothermal Technologies Legacy Collection HelpFAQ | Site Map | Contact Us HomeBasic Search About Publications Advanced Search New Hot Docs News Related Links...

  7. RMOTC - Library - Environmental Documents

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

    Environmental Documents The U.S. Department of Energy National Environmental Policy Act (NEPA) requires careful consideration of the potential environmental consequences of all...

  8. Hazard Baseline Documentation

    Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]

    1995-12-04T23:59:59.000Z

    This standard establishes uniform Office of Environmental Management (EM) guidance on hazard baseline documents that identify and control radiological and non-radiological hazards for all EM facilities.

  9. Ultra-low resistance ohmic contacts to GaN with high Si doping concentrations grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Afroz Faria, Faiza; Guo Jia; Zhao Pei; Li Guowang; Kumar Kandaswamy, Prem; Wistey, Mark; Xing Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

    2012-07-16T23:59:59.000Z

    Ti/Al/Ni/Au ohmic contacts were formed on heavily doped n{sup +} metal-polar GaN samples with various Si doping concentrations grown by molecular beam epitaxy. The contact resistivity (R{sub C}) and sheet resistance (R{sub sh}) as a function of corresponding GaN free carrier concentration (n) were measured. Very low R{sub C} values (<0.09 {Omega} mm) were obtained, with a minimum R{sub C} of 0.035 {Omega} mm on a sample with a room temperature carrier concentration of {approx}5 Multiplication-Sign 10{sup 19} cm{sup -3}. Based on the systematic study, the role of R{sub C} and R{sub sh} is discussed in the context of regrown n{sup +} GaN ohmic contacts for GaN based high electron mobility transistors.

  10. Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN

    SciTech Connect (OSTI)

    Sintonen, Sakari, E-mail: sakari.sintonen@aalto.fi; Suihkonen, Sami; Jussila, Henri; Tuomi, Turkka O.; Lipsanen, Harri [Department of Micro- and Nanosciences, Aalto University School of Electrical Engineering, 02150 Espoo (Finland); Rudzi?ski, Mariusz [Epitaxy Department, Institute of Electronic Materials Technology, 01-919 Warsaw (Poland); Knetzger, Michael; Meissner, Elke [Fraunhofer Institute for Integrated Systems and Device Technology, 91058 Erlangen (Germany); Danilewsky, Andreas [Kristallographie Institut fr Geo- und Umweltnaturwissenschaften, Albert-Ludwigs-Universitt Freiburg, 79104 Freiburg (Germany)

    2014-08-28T23:59:59.000Z

    The crystal quality of bulk GaN crystals is continuously improving due to advances in GaN growth techniques. Defect characterization of the GaN substrates by conventional methods is impeded by the very low dislocation density and a large scale defect analysis method is needed. White beam synchrotron radiation x-ray topography (SR-XRT) is a rapid and non-destructive technique for dislocation analysis on a large scale. In this study, the defect structure of an ammonothermal c-plane GaN substrate was recorded using SR-XRT and the image contrast caused by the dislocation induced microstrain was simulated. The simulations and experimental observations agree excellently and the SR-XRT image contrasts of mixed and screw dislocations were determined. Apart from a few exceptions, defect selective etching measurements were shown to correspond one to one with the SR-XRT results.

  11. Step-flow growth mode instability of N-polar GaN under N-excess

    SciTech Connect (OSTI)

    Chze, C. [TopGaN Ltd., Soko?owska 29/37, 01142 Warszawa (Poland)] [TopGaN Ltd., Soko?owska 29/37, 01142 Warszawa (Poland); Sawicka, M.; Siekacz, M.; ?ucznik, B.; Bo?kowski, M.; Skierbiszewski, C. [TopGaN Ltd., Soko?owska 29/37, 01142 Warszawa (Poland) [TopGaN Ltd., Soko?owska 29/37, 01142 Warszawa (Poland); Institute of High Pressure Physics, PAS, Soko?owska 29/37, 01142 Warszawa (Poland); Turski, H.; Cywi?ski, G.; Smalc-Koziorowska, J.; Weyher, J. L.; Kry?ko, M. [Institute of High Pressure Physics, PAS, Soko?owska 29/37, 01142 Warszawa (Poland)] [Institute of High Pressure Physics, PAS, Soko?owska 29/37, 01142 Warszawa (Poland)

    2013-08-12T23:59:59.000Z

    GaN layers were grown on N-polar GaN substrates by plasma-assisted molecular beam epitaxy under different III/V ratios. Ga-rich conditions assure step-flow growth with atomically flat surface covered by doubly-bunched steps, as for Ga-polar GaN. Growth under N-excess however leads to an unstable step-flow morphology. Particularly, for substrates slightly miscut towards <1010>, interlacing fingers are covered by atomic steps pinned on both sides by small hexagonal pits. In contrast, a three-dimensional island morphology is observed on the Ga-polar equivalent sample. We attribute this result to lower diffusion barriers on N-polar compared to Ga-polar GaN under N-rich conditions.

  12. Band alignment between GaN and ZrO{sub 2} formed by atomic layer deposition

    SciTech Connect (OSTI)

    Ye, Gang; Wang, Hong, E-mail: ewanghong@ntu.edu.sg; Arulkumaran, Subramaniam; Ng, Geok Ing; Li, Yang; Ang, Kian Siong [Novitas, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Zhi Hong [Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore 138602 (Singapore)

    2014-07-14T23:59:59.000Z

    The band alignment between Ga-face GaN and atomic-layer-deposited ZrO{sub 2} was investigated using X-ray photoelectron spectroscopy (XPS). The dependence of Ga 3d and Zr 3d core-level positions on the take-off angles indicated upward band bending at GaN surface and potential gradient in ZrO{sub 2} layer. Based on angle-resolved XPS measurements combined with numerical calculations, valence band discontinuity ?E{sub V} of 1??0.2?eV and conduction band discontinuity ?E{sub C} of 1.2??0.2?eV at ZrO{sub 2}/GaN interface were determined by taking GaN surface band bending and potential gradient in ZrO{sub 2} layer into account.

  13. Substrate-dependent wetting layer formation during GaN growth: Impact on the morphology of the films

    SciTech Connect (OSTI)

    Sidorenko, A.; Peisert, H.; Neumann, H.; Chasse, T. [Universitaet Tuebingen, Institut fuer Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, D-72076 Tuebingen (Germany); Leibniz-Institut fuer Oberflaechenmodifizierung e.V. Permoserstrasse 15, D-04318 Leipzig (Germany); Universitaet Tuebingen, Institut fuer Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, D-72076 Tuebingen (Germany)

    2007-08-15T23:59:59.000Z

    We have compared epitaxial growth of GaN films on 6H-SiC(0001)-({radical}(3)x{radical}(3))R30 deg. -Ga and on (0001)-sapphire. Predeposited Ga layers were nitrided by ion beam assisted molecular beam epitaxy. Whereas on SiC the initially deposited Ga covers the substrate surface completely, on sapphire only Ga droplets are present. The different distribution of the predeposited Ga affects the morphology of GaN significantly. Scanning electron microscopy and atomic force microscopy analysis of the grown films show that the complete wetting of the SiC substrate with Ga enhances finally the size and the flatness of GaN terraces and thus the quality of the film. X-ray photoelectron spectroscopy measurements reveal that metallic Ga resides also on top of the GaN films during the growth.

  14. Photoluminescence study of the 1.047 eV emission in GaN K. Pressela)

    E-Print Network [OSTI]

    Nabben, Reinhard

    GaN/ AlGaN blue green light emitting diode, which has a much higher quantum efficiency than the SiC blue light emitting diode, became possible.2 Presently the wide bandgap semi- conductor GaN is intensively. Especially the 1.19 eV is very intense. Thus one can think of developing a light emitting diode in the near

  15. Comparative Study of the Electronic Band Structure of Strained C-plane and M-plane GaN Films

    E-Print Network [OSTI]

    Ghosh, Sandip

    to the unique c axis of wurtzite GaN, and the spectral features do not change with polarization rotation emitters [1]. The surface normal to an M-plane film is perpen- dicular (?) to the unique c axis of wurtzite (1100)M-plane y C-plane (0001) xc z||c Fig. 1. a) Wurtzite GaN unit cell showing the choice

  16. 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

  17. Growth and characterizations of GaN micro-rods on graphene films for flexible light emitting diodes

    SciTech Connect (OSTI)

    Chung, Kunook; Beak, Hyeonjun; Tchoe, Youngbin; Oh, Hongseok; Yi, Gyu-Chul, E-mail: gcyi@snu.ac.kr [Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Yoo, Hyobin; Kim, Miyoung [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2014-09-01T23:59:59.000Z

    We report the growth of GaN micro-rods and coaxial quantum-well heterostructures on graphene films, together with structural and optical characterization, for applications in flexible optical devices. Graphene films were grown on Cu foil by means of chemical vapor deposition, and used as the substrates for the growth of the GaN micro-rods, which were subsequently transferred onto SiO{sub 2}/Si substrates. Highly Si-doped, n-type GaN micro-rods were grown on the graphene films using metalorganic chemical vapor deposition. The growth and vertical alignment of the GaN micro-rods, which is a critical factor for the fabrication of high-performance light-emitting diodes (LEDs), were characterized using electron microscopy and X-ray diffraction. The GaN micro-rods exhibited promising photoluminescence characteristics for optoelectronic device applications, including room-temperature stimulated emission. To fabricate flexible LEDs, In{sub x}Ga{sub 1x}N/GaN multiple quantum wells and a p-type GaN layer were deposited coaxially on the GaN micro-rods, and transferred onto Ag-coated polymer substrates using lift-off. Ti/Au and Ni/Au metal layers were formed to provide electrical contacts to the n-type and p-type GaN regions, respectively. The micro-rod LEDs exhibited intense emission of visible light, even after transfer onto the flexible polymer substrate, and reliable operation was achieved following numerous cycles of mechanical deformation.

  18. Influence of growth temperature and temperature ramps on deep level defect incorporation in m-plane GaN

    SciTech Connect (OSTI)

    Armstrong, A. M., E-mail: aarmstr@sandia.gov [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Kelchner, K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)] [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Nakamura, S.; DenBaars, S. P. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States) [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Department, University of California, Santa Barbara, California 93106 (United States); Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)] [Materials Department, University of California, Santa Barbara, California 93106 (United States)

    2013-12-02T23:59:59.000Z

    The dependence of deep level defect incorporation in m-plane GaN films grown by metal-organic chemical vapor deposition on bulk m-plane GaN substrates as a function of growth temperature (T{sub g}) and T{sub g} ramping method was investigated using deep level optical spectroscopy. Understanding the influence of T{sub g} on GaN deep level incorporation is important for InGaN/GaN multi-quantum well (MQW) light emitting diodes (LEDs) and laser diodes (LDs) because GaN quantum barrier (QB) layers are grown much colder than thin film GaN to accommodate InGaN QW growth. Deep level spectra of low T{sub g} (800?C) GaN films grown under QB conditions were compared to deep level spectra of high T{sub g} (1150?C) GaN. Reducing T{sub g}, increased the defect density significantly (>50) through introduction of emergent deep level defects at 2.09?eV and 2.9?eV below the conduction band minimum. However, optimizing growth conditions during the temperature ramp when transitioning from high to low T{sub g} substantially reduced the density of these emergent deep levels by approximately 40%. The results suggest that it is important to consider the potential for non-radiative recombination in QBs of LED or LD active regions, and tailoring the transition from high T{sub g} GaN growth to active layer growth can mitigate such non-radiative channels.

  19. Lateral color integration on rare-earth-doped GaN electroluminescent D. S. Lee and A. J. Steckla)

    E-Print Network [OSTI]

    Steckl, Andrew J.

    and thermal robust- ness. GaN films were grown on p-type 111 Si substrate by molecular beam epitaxy MBE growth from solid sources. GaN:RE layers were typically grown for 1 h at either 100 or 400 C substrateLateral color integration on rare-earth-doped GaN electroluminescent thin films D. S. Lee and A. J

  20. Effect of growth temperature on defects in epitaxial GaN film grown by plasma assisted molecular beam epitaxy

    SciTech Connect (OSTI)

    Kushvaha, S. S., E-mail: kushvahas@nplindia.org; Pal, P.; Shukla, A. K.; Joshi, Amish G.; Gupta, Govind; Kumar, M.; Singh, S.; Gupta, Bipin K.; Haranath, D. [CSIR- National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, India 110012 (India)] [CSIR- National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, India 110012 (India)

    2014-02-15T23:59:59.000Z

    We report the effect of growth temperature on defect states of GaN epitaxial layers grown on 3.5 ?m thick GaN epi-layer on sapphire (0001) substrates using plasma assisted molecular beam epitaxy. The GaN samples grown at three different substrate temperatures at 730, 740 and 750 C were characterized using atomic force microscopy and photoluminescence spectroscopy. The atomic force microscopy images of these samples show the presence of small surface and large hexagonal pits on the GaN film surfaces. The surface defect density of high temperature grown sample is smaller (4.0 10{sup 8} cm{sup ?2} at 750 C) than that of the low temperature grown sample (1.1 10{sup 9} cm{sup ?2} at 730 C). A correlation between growth temperature and concentration of deep centre defect states from photoluminescence spectra is also presented. The GaN film grown at 750 C exhibits the lowest defect concentration which confirms that the growth temperature strongly influences the surface morphology and affects the optical properties of the GaN epitaxial films.

  1. Environmental Policy Document Ref

    E-Print Network [OSTI]

    Aickelin, Uwe

    Document Environmental Policy Document Ref EMS.POL.001 Last Revision March 2013 Revision No 5 Page 1 of 1 Environmental Policy Through teaching and research the University of the West of England should be managed so as to minimise environmental harm. This policy commits the University of the West

  2. IMPRESS CONNECT DOCUMENT ORDERING

    E-Print Network [OSTI]

    Asaithambi, Asai

    IMPRESS CONNECT DOCUMENT ORDERING USER GUIDE FOR UNF August 2010 #12;OFFICEMAX IMPRESS CONNECT USERMax (case sensitive) Click on "Create New Custom Print Order" under Print & Document Services #12;The first landing page. You will see 3 options across the top of the landing page: Order Jobs, Track Jobs, Manage

  3. IDC System Specification Document.

    SciTech Connect (OSTI)

    Clifford, David J.

    2014-12-01T23:59:59.000Z

    This document contains the system specifications derived to satisfy the system requirements found in the IDC System Requirements Document for the IDC Reengineering Phase 2 project. Revisions Version Date Author/Team Revision Description Authorized by V1.0 12/2014 IDC Reengineering Project Team Initial delivery M. Harris

  4. Presidential Documents Federal Register

    E-Print Network [OSTI]

    Presidential Documents 67249 Federal Register Vol. 65, No. 218 Thursday, November 9, 2000 Title 3 principles set forth in section 2, agencies shall adhere, to the extent permitted by law, to the following #12;67250 Federal Register / Vol. 65, No. 218 / Thursday, November 9, 2000 / Presidential Documents (a

  5. Calculation of linear and second-order optical response in wurtzite GaN and AlN James L. P. Hughes, Y. Wang, and J. E. Sipe

    E-Print Network [OSTI]

    Sipe,J. E.

    Calculation of linear and second-order optical response in wurtzite GaN and AlN James L. P. Hughes and nonlinear optical response of GaN and AlN in the wurtzite structure. The dielectric function ( ), the second there to the wurtzite mate- rials GaN and AlN. Our evaluation of optical response is based on a first principles

  6. Nucleation and Stoichiometry Dependence of rutile-TiO2(001)/GaN(0001) Thin Films Grown by Plasma-Assisted Molecular Beam Epitaxy

    E-Print Network [OSTI]

    Feenstra, Randall

    the initial nucleation and the stoichiometry of rutile- TiO2(001) grown on wurtzite GaN(0001) by radio explore the growth of rutile-TiO2(001) on wurtzite GaN(0001) by oxygen plasma-assisted molecular beam) was maintained constant at 400 W. The substrates were commercially available wurtzite Ga-polar GaN(0001) grown

  7. Nonparabolicity of the conduction band of wurtzite GaN S. Syed, J. B. Heroux, Y. J. Wang, M. J. Manfra, R. J. Molnar et al.

    E-Print Network [OSTI]

    Manfra, Michael J.

    Nonparabolicity of the conduction band of wurtzite GaN S. Syed, J. B. Heroux, Y. J. Wang, M. J://apl.aip.org/about/rights_and_permissions #12;Nonparabolicity of the conduction band of wurtzite GaN S. Syeda) Department of Applied Physics of the nonparabolicity NP of the con- duction band of wurtzite GaN currently remains controver- sial. NP of a band can

  8. 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

  9. Band gap and band parameters of InN and GaN from quasiparticle energy calculations based on exact-exchange density-functional theory

    E-Print Network [OSTI]

    Band gap and band parameters of InN and GaN from quasiparticle energy calculations based on exact; published online 20 October 2006 The authors have studied the electronic structure of InN and GaN employing. © 2006 American Institute of Physics. DOI: 10.1063/1.2364469 The group III-nitrides AlN, GaN, and In

  10. Shock-induced band-gap shift in GaN: Anisotropy of the deformation potentials H. Y. Peng, M. D. McCluskey,* and Y. M. Gupta

    E-Print Network [OSTI]

    McCluskey, Matthew

    Shock-induced band-gap shift in GaN: Anisotropy of the deformation potentials H. Y. Peng, M. D. Mc Alto, California 94304, USA Received 19 October 2004; published 24 March 2005 The band-gap shift of GaN=1.9 eV, and D4=-1.0 eV. These values indicate that the deformation potentials in wurtzite GaN

  11. Submitted to J. Vac. Sci. Technol., December 11, 1998 1 Growth of Hf and HfN on GaN by Molecular Beam Epitaxy

    E-Print Network [OSTI]

    Cohen, Philip I.

    Submitted to J. Vac. Sci. Technol., December 11, 1998 1 Growth of Hf and HfN on GaN by Molecular-type GaN(0001) by MBE using a custom built Hf electron beam source and an ammonia leak. The films were). It was found that epitaxial growth of Hf is possible even at room temperature. GaN films varying in thickness

  12. Room-temperature-grown rare-earth-doped GaN luminescent thin films D. S. Lee and A. J. Steckla)

    E-Print Network [OSTI]

    Steckl, Andrew J.

    efforts to achieve this goal with GaN growth on oxide films or on glass substrates36 being a main focus: 50100 C. GaN films were grown on p-type 111 Si substrate by MBE with a Ga elemental sourceRoom-temperature-grown rare-earth-doped GaN luminescent thin films D. S. Lee and A. J. Steckla

  13. Growth of cubic GaN on nano-patterned 3C-SiC/Si (0 0 1) substrates R.M. Kemper n

    E-Print Network [OSTI]

    As, Donat Josef

    Growth of cubic GaN on nano-patterned 3C-SiC/Si (0 0 1) substrates R.M. Kemper n , M. Weinl, C matched nano- patterned substrates. In hexagonal GaN inherent spontaneous and piezoelectric polarization conditions to achieve heteroepitaxial growth of cubic GaN [8]. The most ade- quate substrate is 3C-SiC (0 0 1

  14. Materials physics and device development for improved efficiency of GaN HEMT high power amplifiers.

    SciTech Connect (OSTI)

    Kurtz, Steven Ross; Follstaedt, David Martin; Wright, Alan Francis; Baca, Albert G.; Briggs, Ronald D.; Provencio, Paula Polyak; Missert, Nancy A.; Allerman, Andrew Alan; Marsh, Phil F.; Koleske, Daniel David; Lee, Stephen Roger; Shul, Randy John; Seager, Carleton Hoover; Tigges, Christopher P.

    2005-12-01T23:59:59.000Z

    GaN-based microwave power amplifiers have been identified as critical components in Sandia's next generation micro-Synthetic-Aperture-Radar (SAR) operating at X-band and Ku-band (10-18 GHz). To miniaturize SAR, GaN-based amplifiers are necessary to replace bulky traveling wave tubes. Specifically, for micro-SAR development, highly reliable GaN high electron mobility transistors (HEMTs), which have delivered a factor of 10 times improvement in power performance compared to GaAs, need to be developed. Despite the great promise of GaN HEMTs, problems associated with nitride materials growth currently limit gain, linearity, power-added-efficiency, reproducibility, and reliability. These material quality issues are primarily due to heteroepitaxial growth of GaN on lattice mismatched substrates. Because SiC provides the best lattice match and thermal conductivity, SiC is currently the substrate of choice for GaN-based microwave amplifiers. Obviously for GaN-based HEMTs to fully realize their tremendous promise, several challenges related to GaN heteroepitaxy on SiC must be solved. For this LDRD, we conducted a concerted effort to resolve materials issues through in-depth research on GaN/AlGaN growth on SiC. Repeatable growth processes were developed which enabled basic studies of these device layers as well as full fabrication of microwave amplifiers. Detailed studies of the GaN and AlGaN growth of SiC were conducted and techniques to measure the structural and electrical properties of the layers were developed. Problems that limit device performance were investigated, including electron traps, dislocations, the quality of semi-insulating GaN, the GaN/AlGaN interface roughness, and surface pinning of the AlGaN gate. Surface charge was reduced by developing silicon nitride passivation. Constant feedback between material properties, physical understanding, and device performance enabled rapid progress which eventually led to the successful fabrication of state of the art HEMT transistors and amplifiers.

  15. Probing temperature gradients within the GaN buffer layer of AlGaN/GaN high electron mobility transistors with Raman thermography

    SciTech Connect (OSTI)

    Hodges, C., E-mail: chris.hodges@bristol.ac.uk; Pomeroy, J.; Kuball, M. [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2014-02-14T23:59:59.000Z

    We demonstrate the ability of confocal Raman thermography using a spatial filter and azimuthal polarization to probe vertical temperature gradients within the GaN buffer layer of operating AlGaN/GaN high electron mobility transistors. Temperature gradients in the GaN layer are measured by using offset focal planes to minimize the contribution from different regions of the GaN buffer. The measured temperature gradient is in good agreement with a thermal simulation treating the GaN thermal conductivity as homogeneous throughout the layer and including a low thermal conductivity nucleation layer to model the heat flow between the buffer and substrate.

  16. Influence of vicinal sapphire substrate on the properties of N-polar GaN films grown by metal-organic chemical vapor deposition

    SciTech Connect (OSTI)

    Lin, Zhiyu; Zhang, Jincheng, E-mail: jchzhang@xidian.edu.cn; Xu, Shengrui; Chen, Zhibin; Yang, Shuangyong; Tian, Kun; Hao, Yue [Key Lab of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an, Shaanxi 710071 (China); Su, Xujun [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123 (China); Shi, Xuefang [School of Advanced Materials and Nanotechnology, Xidian University, Xi'an, Shaanxi 710071 (China)

    2014-08-25T23:59:59.000Z

    The influence of vicinal sapphire substrates on the growth of N-polar GaN films by metal-organic chemical vapor deposition is investigated. Smooth GaN films without hexagonal surface feature are obtained on vicinal substrate. Transmission electron microscope results reveal that basal-plane stacking faults are formed in GaN on vicinal substrate, leading to a reduction in threading dislocation density. Furthermore, it has been found that there is a weaker yellow luminescence in GaN on vicinal substrate than that on (0001) substrate, which might be explained by the different trends of the carbon impurity incorporation.

  17. Content-Based Document Image Retrieval in Complex Document Collections

    E-Print Network [OSTI]

    Content-Based Document Image Retrieval in Complex Document Collections G. Agama, S. Argamona, O address the problem of content-based image retrieval in the context of complex document images. Complex document are documents that typically start out on paper and are then electronically scanned. These docu

  18. View of software for HEP experiments

    SciTech Connect (OSTI)

    Johnstad, H.; Lebrun, P.; Lessner, E.S.; Montgomery, H.E.

    1986-05-01T23:59:59.000Z

    A view of the software structure typical of a High Energy Physics experiment is given and the availability of general software modules in most of the important regions is discussed. The aim is to provide a framework for discussion of capabilities and inadequecies and thereby define areas where effort should be assigned and perhaps also to serve as a useful source document for the newcomer to High Energy Physics. 74 refs.

  19. Spectroscopic study of semipolar (112{sup }2)-HVPE GaN exhibiting high oxygen incorporation

    SciTech Connect (OSTI)

    Schustek, Philipp, E-mail: philipp.schustek@gmail.com [Institute of Quantum Matter, Ulm University, 89081 Ulm (Germany); Research Unit, Parc Sanitari Sant Joan de Du and Foundation Sant Joan de Du, Esplugues de Llobregat, 08950, Barcelona (Spain); Hocker, Matthias; Thonke, Klaus [Institute of Quantum Matter, Ulm University, 89081 Ulm (Germany); Klein, Martin; Scholz, Ferdinand [Institute of Optoelectronics, Ulm University, 89081 Ulm (Germany); Simon, Ulrich [Scientific Computing Centre Ulm, Ulm University, 89081 Ulm (Germany)

    2014-10-28T23:59:59.000Z

    Spatially resolved luminescence and Raman spectroscopy investigations are applied to a series of (112{sup }2)-GaN samples grown by hydride vapor phase epitaxy (HVPE) grown over an initial layer deposited by metal organic vapor phase epitaxy on patterned sapphire substrates. Whereas these two differently grown GaN layers are crystallographically homogeneous, they differ largely in their doping level due to high unintentional oxygen uptake in the HVPE layer. This high doping shows up in luminescence spectra, which can be explained by a free-electron recombination band for which an analytical model considering the Burstein-Moss shift, conduction band tailing, and the bandgap renormalization is included. Secondary ion mass spectrometry, Raman spectroscopy, and Hall measurements concordantly determine the electron density to be above 10{sup 19?}cm{sup ?3}. In addition, the strain state is assessed by Raman spectroscopy and compared to a finite element analysis.

  20. Charge transfer in Fe-doped GaN: The role of the donor

    SciTech Connect (OSTI)

    Sunay, Ustun; Dashdorj, J.; Zvanut, M. E.; Harrison, J. G. [Department of Physics, University of Alabama at Birmingham, 1300 University Blvd., CH 310, Birmingham, Alabama 35294-1170 (United States); Leach, J. H.; Udwary, K. [Kyma Technologies, 8829 Midway West Rd., Raleigh, North Carolina 27617 (United States)

    2014-02-21T23:59:59.000Z

    Several nitride-based device structures would benefit from the availability of high quality, large-area, freestanding semi-insulating GaN substrates. Due to the intrinsic n-type nature of GaN, however, the incorporation of compensating centers such as Fe is necessary to achieve the high resistivity required. We are using electron paramagnetic resonance (EPR) to explore charge transfer in 450 um thick GaN:Fe plates to understand the basic mechanisms related to compensation so that the material may be optimized for device applications. The results suggest that the simple model based on one shallow donor and a single Fe level is insufficient to describe compensation. Rather, the observation of the neutral donor and Fe3+ indicates that either the two species are spatially segregated or additional compensating and donor defects must be present.

  1. Strong light-matter coupling in ultrathin double dielectric mirror GaN microcavities

    SciTech Connect (OSTI)

    Bejtka, K.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France); Reveret, F.; Vasson, A.; Leymarie, J. [LASMEA, UMR 6602 UBP/CNRS, 24 Avenue des Landais, F-63177 Aubiere Cedex (France); Edwards, P. R. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Sellers, I. R.; Duboz, J. Y.; Leroux, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France)

    2008-06-16T23:59:59.000Z

    Strong light-matter coupling is demonstrated at low temperature in an ultrathin GaN microcavity fabricated using two silica/zirconia Bragg mirrors, in addition to a three-period epitaxial (Al,Ga)N mirror serving as an etch stop and assuring good quality of the overgrown GaN. The {lambda}/2 cavity is grown by molecular beam epitaxy on a Si substrate. Analysis of angle-resolved data reveal key features of the strong coupling regime in both reflectivity and transmission spectra at 5 K: anticrossing with a normal mode splitting of 43{+-}2 meV and 56{+-}2 meV for reflectivity and transmission, respectively, and narrowing of the lower polariton linewidth near resonance.

  2. Document | Department of Energy

    Office of Environmental Management (EM)

    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 1,006 492 742 33 1112011AT&T,Office of Policy,Policy ActDetroit7471 Federal RegisterDocument DocumentDocument

  3. Document | Department of Energy

    Office of Environmental Management (EM)

    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 1,006 492 742 33 1112011AT&T,Office of Policy,Policy ActDetroit7471 Federal RegisterDocumentDocument Document

  4. Document | Department of Energy

    Energy Savers [EERE]

    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 onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed offOCHCO OverviewAttachments461-93Do-It-Yourself ProjectsDocument Document Extracted PagesDocument

  5. Europium doping of zincblende GaN by ion implantation K. Lorenz,1,2,a

    E-Print Network [OSTI]

    As, Donat Josef

    /channeling spectrometry. A low concentration 10% of wurtzite phase inclusions was observed by XRD analysis in as-lattice parameter of wurtzite GaN W-GaN . For ZB-GaN:Eu, a large fraction of Eu ions is found on a high symmetry-GaN:Eu. The implantation damage in ZB-GaN:Eu could partly be removed by thermal annealing, but an increase in the wurtzite

  6. K.K. Gan ATLAS Pixel Week 1 New Results on Opto-Electronics

    E-Print Network [OSTI]

    Gan, K. K.

    with lower thresholds with BPM/DRX ] opto-board design is compatible with BPM/DRX PIN Current Thresholds with BPM/DRX 0 5 10 15 20 25 30 35 link#1 link#2 link#3 link#4 link#5 link#6 link#7 Ipin(mA) Opto-Board on Test Board Opto-Board on Test Board with BPM/DRX #12;K.K. Gan ATLAS Pixel Week 8 l one irradiated VCSEL

  7. Structure and electronic properties of mixed (a?+?c) dislocation cores in GaN

    SciTech Connect (OSTI)

    Horton, M. K., E-mail: m.horton11@imperial.ac.uk [Department Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Rhode, S. L. [Department Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Moram, M. A. [Department Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-08-14T23:59:59.000Z

    Classical atomistic models and atomic-resolution scanning transmission electron microscopy studies of GaN films reveal that mixed (a?+?c)-type dislocations have multiple different core structures, including a dissociated structure consisting of a planar fault on one of the (12{sup }10) planes terminated by two different partial dislocations. Density functional theory calculations show that all cores introduce localized states into the band gap, which affects device performance.

  8. 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.

  9. Cr Atom Alignment in Cr-Delta-Doped GaN

    SciTech Connect (OSTI)

    Kimura, S.; Emura, S.; Zhou, Y. K.; Choi, S. W.; Yamauchi, Y.; Hasegawa, S.; Asahi, H. [Institute of Scientific and Industrial Research, Osaka University, 8-1, Mihogaoka, Osaka, 567-0047 (Japan); Ofuchi, H. [SPring-8 / Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198 (Japan); Nakata, Y. [College of Science and Engineering, Iwaki Meisei University, Iwaki, Fukushima 970-8551 (Japan)

    2007-02-02T23:59:59.000Z

    Structural properties and Cr atom alignments in Cr-delta doped GaN grown by molecular beam epitaxy are studied with transmission electron microscopy and X-ray absorption fine structure (XAFS) measurements. It is found that the environment around Cr atoms in delta-doped samples is dramatically changed under various growth conditions. The XAFS analysis of these synthesized layers suggests that new Cr-related complexes are grown.

  10. Optimization of ion-atomic beam source for deposition of GaN ultrathin films

    SciTech Connect (OSTI)

    Mach, Jind?ich, E-mail: mach@fme.vutbr.cz; Kolbal, Miroslav; Zlmal, Jakub; Voborny, Stanislav; Bartok, Miroslav; ikola, Tom [Institute of Physical Engineering, Brno University of Technology, Technick 2, 616 69 Brno (Czech Republic); CEITEC BUT, Brno University of Technology, Technick 10, 61669 Brno (Czech Republic); amo?il, Tom [Institute of Physical Engineering, Brno University of Technology, Technick 2, 616 69 Brno (Czech Republic)

    2014-08-15T23:59:59.000Z

    We describe the optimization and application of an ion-atomic beam source for ion-beam-assisted deposition of ultrathin films in ultrahigh vacuum. The device combines an effusion cell and electron-impact ion beam source to produce ultra-low energy (20200 eV) ion beams and thermal atomic beams simultaneously. The source was equipped with a focusing system of electrostatic electrodes increasing the maximum nitrogen ion current density in the beam of a diameter of ?15 mm by one order of magnitude (j ? 1000 nA/cm{sup 2}). Hence, a successful growth of GaN ultrathin films on Si(111) 7 7 substrate surfaces at reasonable times and temperatures significantly lower (RT, 300?C) than in conventional metalorganic chemical vapor deposition technologies (?1000?C) was achieved. The chemical composition of these films was characterized in situ by X-ray Photoelectron Spectroscopy and morphology ex situ using Scanning Electron Microscopy. It has been shown that the morphology of GaN layers strongly depends on the relative Ga-N bond concentration in the layers.

  11. Anisotropy of effective electron masses in highly doped nonpolar GaN

    SciTech Connect (OSTI)

    Feneberg, Martin, E-mail: martin.feneberg@ovgu.de; Lange, Karsten; Lidig, Christian; Wieneke, Matthias; Witte, Hartmut; Blsing, Jrgen; Dadgar, Armin; Krost, Alois; Goldhahn, Rdiger [Institut fr Experimentelle Physik, Otto-von-Guericke-Universitt Magdeburg, Universittsplatz 2, 39106 Magdeburg (Germany)] [Institut fr Experimentelle Physik, Otto-von-Guericke-Universitt Magdeburg, Universittsplatz 2, 39106 Magdeburg (Germany)

    2013-12-02T23:59:59.000Z

    The anisotropic effective electron masses in wurtzite GaN are determined by generalized infrared spectroscopic ellipsometry. Nonpolar (112{sup }0) oriented thin films allow accessing both effective masses, m{sub ?}{sup *} and m{sub ?}{sup *}, by determining the screened plasma frequencies. A n-type doping range up to 1.7??10{sup 20}?cm{sup ?3} is investigated. The effective mass ratio m{sub ?}{sup *}/m{sub ?}{sup *} is obtained with highest accuracy and is found to be 1.11 independent on electron concentration up to 1.2??10{sup 20}?cm{sup ?3}. For higher electron concentrations, the conduction band non-parabolicity is mirrored in changes. Absolute values for effective electron masses depend on additional input of carrier concentrations determined by Hall effect measurements. We obtain m{sub ?}{sup *}=(0.2390.004)m{sub 0} and m{sub ?}{sup *}=(0.2160.003)m{sub 0} for the parabolic range of the GaN conduction band. Our data are indication of a parabolic GaN conduction band up to an energy of approximately 400?meV above the conduction band minimum.

  12. Valence band hybridization in N-rich GaN1-xAsx alloys

    SciTech Connect (OSTI)

    Wu, J.; Walukiewicz, W.; Yu, K.M.; Denlinger, J.D.; Shan, W.; Ager III, J.W.; Kimura, A.; Tang, H.F.; Kuech, T.F.

    2004-05-04T23:59:59.000Z

    We have used photo-modulated transmission and optical absorption spectroscopies to measure the composition dependence of interband optical transitions in N-rich GaN{sub 1-x}As{sub x} alloys with x up to 0.06. The direct bandgap gradually decreases as x increases. In the dilute x limit, the observed band gap approaches 2.8 eV; this limiting value is attributed to a transition between the As localized level, which has been previously observed in As-doped GaN at 0.6 eV above the valence band maximum in As-doped GaN, and the conduction band minimum. The structure of the valence band of GaN{sub 1-x}As{sub x} is explained by the hybridization of the localized As states with the extended valence band states of GaN matrix. The hybridization is directly confirmed by soft x-ray emission experiments. To describe the electronic structure of the GaN{sub 1-x}As{sub x} alloys in the entire composition range a linear interpolation is used to combine the effects of valence band hybridization in N-rich alloys with conduction band anticrossing in As-rich alloys.

  13. UESC Enabling Documents

    Broader source: Energy.gov [DOE]

    Presentationgiven at the Spring 2009 Federal Utility Partnership Working Group (FUPWG) meetingdiscusses the enabling documents to help federal contract officers establish utility energy service contracts (UESCs).

  14. TUchem Documentation Introduction

    E-Print Network [OSTI]

    Wolfgang, Paul

    TUchem Documentation Introduction TUchem is an automated chemical inventory database system design, such as inventory import, report generation, location management, and a user-friendly look-and-feel. The motivation

  15. Presidential Documents Federal Register

    E-Print Network [OSTI]

    Presidential Documents 67249 Federal Register Vol. 65, No. 218 Thursday, November 9, 2000 Title 3 principles set forth in section 2, agencies shall adhere, to the extent permitted by law, to the following

  16. Document Type: Subject Terms

    E-Print Network [OSTI]

    Major, Arkady

    Title: Authors: Source: Document Type: Subject Terms: Abstract: Full Text Word Count: ISSN at creating team results. In fact, it's priceless. Managers in Western corporations have received a lifetime

  17. Heteroepitaxial VO{sub 2} thin films on GaN: Structure and metal-insulator transition characteristics

    SciTech Connect (OSTI)

    Zhou You; Ramanathan, Shriram [Harvard School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2012-10-01T23:59:59.000Z

    Monolithic integration of correlated oxide and nitride semiconductors may open up new opportunities in solid-state electronics and opto-electronics that combine desirable functional properties of both classes of materials. Here, we report on epitaxial growth and phase transition-related electrical properties of vanadium dioxide (VO{sub 2}) thin films on GaN epitaxial layers on c-sapphire. The epitaxial relation is determined to be (010){sub vo{sub 2}} parallel (0001){sub GaN} parallel (0001){sub A1{sub 2O{sub 3}}} and [100]{sub vo{sub 2}} parallel [1210]{sub GaN} parallel [0110]{sub A1{sub 2O{sub 3}}} from x-ray diffraction. VO{sub 2} heteroepitaxial growth and lattice mismatch are analyzed by comparing the GaN basal plane (0001) with the almost close packed corrugated oxygen plane in vanadium dioxide and an experimental stereographic projection describing the orientation relationship is established. X-ray photoelectron spectroscopy suggests a slightly oxygen rich composition at the surface, while Raman scattering measurements suggests that the quality of GaN layer is not significantly degraded by the high-temperature deposition of VO{sub 2}. Electrical characterization of VO{sub 2} films on GaN indicates that the resistance changes by about four orders of magnitude upon heating, similar to epitaxial VO{sub 2} films grown directly on c-sapphire. It is shown that the metal-insulator transition could also be voltage-triggered at room temperature and the transition threshold voltage scaling variation with temperature is analyzed in the framework of a current-driven Joule heating model. The ability to synthesize high quality correlated oxide films on GaN with sharp phase transition could enable new directions in semiconductor-photonic integrated devices.

  18. Investigation of MOVPE-grown GaN layers doped with As atoms A. F. Tsatsul'nikov, B. Ya. Ber, A. P. Kartashova, Yu. A. Kudryavtsev, N. N. Ledentsov,

    E-Print Network [OSTI]

    Nabben, Reinhard

    Investigation of MOVPE-grown GaN layers doped with As atoms A. F. Tsatsul'nikov, B. Ya. Ber, A. P vapor-phase epitaxy. It is shown that the deposition of GaAs on a GaN surface relieves stresses in the GaN layer. The high-temperature overgrowth of a thin GaAs layer by a GaN layer causes As atoms

  19. World Views From fragmentation

    E-Print Network [OSTI]

    .......................................................11 2. The Seven Components of a World View...................................................... 20 3. The Unity of the Seven Sub........................................... 25 5. The Purpose of the group `Worldviews

  20. Michigan Questionnaire Documentation System (MQDS)

    E-Print Network [OSTI]

    Cheung, Gina-Qian

    2013-04-03T23:59:59.000Z

    The Michigan Questionnaire Documentation System (MQDS) is a powerful tool used to help create questionnaire documentation, with or without summary statistics, and other documentation based on the Blaise data model for a study. MQDS works by: 1...

  1. PORTAL Aggregation Analysis and Documentation

    E-Print Network [OSTI]

    Bertini, Robert L.

    PORTAL Aggregation Analysis and Documentation Kristin A. Tufte Portland State University Introduction This document describes the aggregation procedures for PORTAL . Analysis of different aggregation system. Details on the status values and their descriptions can be found in the SWARM documentation

  2. Documentation Requirements for Sensory Impairments

    E-Print Network [OSTI]

    Documentation Requirements for Sensory Impairments Vision and Hearing Students, faculty, staff documentation requirements: 1. Requirements of the PRACTITIONER: A) Ophthalmologists and optometrists of interest. C) Documentation must be typed, dated and signed by the evaluator and submitted to ODR

  3. Published November, 1997 1997 Documentation

    E-Print Network [OSTI]

    Goldman, Steven A.

    Published November, 1997 1997 Documentation Guidelines for Evaluation and Management Services;2 1997 DOCUMENTATION GUIDELINES FOR EVALUATION AND MANAGEMENT SERVICES I. INTRODUCTION WHAT...............................................................................................................................2 What Is Documentation and Why Is it Important

  4. Growth of GaN films with controlled out-of-plane texture on Si wafers Jung-Il Hong , Yanling Chang, Yong Ding, Zhong Lin Wang , Robert L. Snyder

    E-Print Network [OSTI]

    Wang, Zhong L.

    Growth of GaN films with controlled out-of-plane texture on Si wafers Jung-Il Hong , Yanling Chang Interface structure GaN films were deposited on Si (400) wafers by a pulsed laser deposition technique, thereby achieving polar or nonpolar film surfaces as desired. The GaN film and Si substrate were found

  5. Total current collapse in High-Voltage GaN MIS-HEMTs induced by Zener trapping D. Jin, J. Joh*, S. Krishnan*, N. Tipirneni*, S. Pendharkar* and J. A. del Alamo

    E-Print Network [OSTI]

    del Alamo, Jess A.

    Total current collapse in High-Voltage GaN MIS-HEMTs induced by Zener trapping D. Jin, J. Joh*, S collapse in GaN MIS-HEMTs for >600 V operation. Extreme trapping leading to total current collapse has been trapping ("Zener trapping") inside the AlGaN barrier or the GaN channel layers. The trapping takes place

  6. Vacancies in GaN bulk and nanowires: effect of self-interaction corrections This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Vacancies in GaN bulk and nanowires: effect of self-interaction corrections This article has been 24 (2012) 255801 (8pp) doi:10.1088/0953-8984/24/25/255801 Vacancies in GaN bulk and nanowires: effect vacancies in gallium nitride (GaN) bulk and nanowires using self-interaction corrected pseudopotentials (SIC

  7. Document Imaging | Department of Energy

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

    Imaging Converting Paper Documents into Electronic Files Converting paper documents into electronic files helps us manage, store, access and archive the organizational information...

  8. Important Trinity / NERSC-8 Documents

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

    RFP Important Trinity NERSC-8 Documents Important Trinity NERSC-8 Documents Trinity NERSC-8 Use Case Scenarios for Burst Buffer and Power Management PDF Facility Limits...

  9. DOCUMENTATION SPECIFIC TASK TRAINING PROGRAM

    E-Print Network [OSTI]

    Illinois at Urbana-Champaign, University of

    DOCUMENTATION APPENDIX SPECIFIC TASK TRAINING PROGRAM Conducted by the ILLINOIS CENTER ............................................................. Coordination of Contract Documents Art.105.05 Appendix Page 14

  10. Low dislocation GaN via defect-filtering, self-assembled SiO2-sphere layers.

    SciTech Connect (OSTI)

    Wang, George T.; Li, Qiming

    2009-09-01T23:59:59.000Z

    The III-nitride (AlGaInN) materials system forms the foundation for white solid-state lighting, the adoption of which could significantly reduce U.S. energy needs. While the growth of GaN-based devices relies on heteroepitaxy on foreign substrates, the heteroepitaxial layers possess a high density of dislocations due to poor lattice and thermal expansion match. These high dislocation densities have been correlated with reduced internal quantum efficiency and lifetimes for GaN-based LEDs. Here, we demonstrate an inexpensive method for dislocation reduction in GaN grown on sapphire and silicon substrates. This technique, which requires no lithographic patterning, GaN is selectively grown through self-assembled layers of silica microspheres which act to filter out dislocations. Using this method, the threading dislocation density for GaN on sapphire was reduced from 3.3 x 10{sup 9} cm{sup -2} to 4.0 x 10{sup 7} cm{sup -2}, and from the 10{sup 10} cm{sup -2} range to {approx}6.0 x 10{sup 7} cm{sup -2} for GaN on Si(111). This large reduction in dislocation density is attributed to a dislocation blocking and bending by the unique interface between GaN and silica microspheres.

  11. Multicycle rapid thermal annealing optimization of Mg-implanted GaN: Evolution of surface, optical, and structural properties

    SciTech Connect (OSTI)

    Greenlee, Jordan D., E-mail: jordan.greenlee.ctr@nrl.navy.mil [National Research Council, 500 Fifth St. NW, Washington, DC 20001 (United States); Feigelson, Boris N.; Anderson, Travis J.; Hite, Jennifer K.; Mastro, Michael A.; Eddy, Charles R.; Hobart, Karl D.; Kub, Francis J. [Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (United States); Tadjer, Marko J. [American Society for Engineering Education, 1818 N St. NW, Washington, DC 20036 (United States)

    2014-08-14T23:59:59.000Z

    The first step of a multi-cycle rapid thermal annealing process was systematically studied. The surface, structure, and optical properties of Mg implanted GaN thin films annealed at temperatures ranging from 900 to 1200?C were investigated by Raman spectroscopy, photoluminescence, UV-visible spectroscopy, atomic force microscopy, and Nomarski microscopy. The GaN thin films are capped with two layers of in-situ metal organic chemical vapor deposition -grown AlN and annealed in 24 bar of N{sub 2} overpressure to avoid GaN decomposition. The crystal quality of the GaN improves with increasing annealing temperature as confirmed by UV-visible spectroscopy and the full widths at half maximums of the E{sub 2} and A{sub 1} (LO) Raman modes. The crystal quality of films annealed above 1100?C exceeds the quality of the as-grown films. At 1200?C, Mg is optically activated, which is determined by photoluminescence measurements. However, at 1200?C, the GaN begins to decompose as evidenced by pit formation on the surface of the samples. Therefore, it was determined that the optimal temperature for the first step in a multi-cycle rapid thermal anneal process should be conducted at 1150?C due to crystal quality and surface morphology considerations.

  12. Ga induced superstructures as templates for lattice matched hetroepitaxial growth of GaN on Si(111) substrate

    SciTech Connect (OSTI)

    Kumar, Praveen; Kuyyalil, Jithesh; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, 560 064 Bangalore (India)

    2010-11-29T23:59:59.000Z

    High quality GaN is grown by plasma assisted molecular beam epitaxy on Ga induced superstructural phases of Si(111)7x7. Three stable surface phases induced by Ga adsorption, viz., (1x1), (6.3x6.3), and ({radical}3x{radical}3)R30 deg., are employed as templates to grow epitaxial (0001) GaN thin films. GaN grown on Si({radical}3x{radical}3)R30 deg. -Ga is found to be highly crystalline with intense (0002) x-ray diffraction and photoluminescence peaks with low full width at half maximum, low surface roughness, and stoichiometric surface composition. The high quality of these GaN films formed at a low temperature of 400 deg. C is explained by the integral (x2) lattice matching between the unit cell of GaN and the ({radical}3x{radical}3) phase. The experiments demonstrate a plausible approach of adsorbate induced surface modifications as templates for III-V hetroepitaxy on Si surfaces.

  13. The effect of substrate on high-temperature annealing of GaN epilayers: Si versus sapphire

    SciTech Connect (OSTI)

    Pastor, D.; Cusco, R.; Artus, L.; Gonzalez-Diaz, G.; Iborra, E.; Jimenez, J.; Peiro, F.; Calleja, E. [Institut Jaume Almera, Consell Superior d'Investigacions Cientifiques (CSIC), Lluis Sole i Sabaris s.n., 08028 Barcelona (Spain); Departamento Fisica Aplicada III, Universidad Complutense, 28040 Madrid (Spain); Departamento Tecnologia Electronica, ETSIT, Universidad Politecnica, 28040 Madrid (Spain); Departamento Fisica de la Materia Condensada, ETSII, Universidad de Valladolid, 47011 Valladolid (Spain); Departamento Electronica, Universidad de Barcelona, 08028 Barcelona (Spain); ISOM, Universidad Politecnica, Ciudad Universitaria, 28040 Madrid, Spain and Departamento Ingenieria Electronica, ETSIT, Universidad Politecnica, Ciudad Universitaria, 28040 Madrid (Spain)

    2006-08-15T23:59:59.000Z

    We have studied the effects of rapid thermal annealing at 1300 deg.C on GaN epilayers grown on AlN buffered Si(111) and on sapphire substrates. After annealing, the epilayers grown on Si display visible alterations with craterlike morphology scattered over the surface. The annealed GaN/Si layers were characterized by a range of experimental techniques: scanning electron microscopy, optical confocal imaging, energy dispersive x-ray microanalysis, Raman scattering, and cathodoluminescence. A substantial Si migration to the GaN epilayer was observed in the crater regions, where decomposition of GaN and formation of Si{sub 3}N{sub 4} crystallites as well as metallic Ga droplets and Si nanocrystals have occurred. The average diameter of the Si nanocrystals was estimated from Raman scattering to be around 3 nm. Such annealing effects, which are not observed in GaN grown on sapphire, are a significant issue for applications of GaN grown on Si(111) substrates when subsequent high-temperature processing is required.

  14. NEWS & VIEWS Glass dynamics

    E-Print Network [OSTI]

    Weeks, Eric R.

    NEWS & VIEWS Glass dynamics Diverging views on glass transition Gregory B. mc.mckenna@ttu.edu T he glass transition is one of the most intriguing phenomena in the world of soft condensed matter. Despite decades of study, many aspects of the behaviour of glass-forming liquids remain elusive

  15. Formation of manganese -doped atomic layer in wurtzite GaN Meng Shi, Abhijit Chinchore, Kangkang Wang, Andrada-Oana Mandru, Yinghao Liu et al.

    E-Print Network [OSTI]

    Formation of manganese -doped atomic layer in wurtzite GaN Meng Shi, Abhijit Chinchore, Kangkang in wurtzite GaN Meng Shi, Abhijit Chinchore, Kangkang Wang, Andrada-Oana Mandru, Yinghao Liu, and Arthur R 2012) We describe the formation of a d-doped manganese layer embedded within c-plane wurtzite gallium

  16. Submitted to J. Appl. Phys. November 4, 1998; not for further distribution 1 Structure and Composition of GaN(0001) A and B Surfaces

    E-Print Network [OSTI]

    Cohen, Philip I.

    , Poland, 01-141 Both c-plane surfaces of bulk GaN crystals were examined using reflection high-energy, Sokololowska 29, Warsaw, Poland, 01-141 B.E. Ishaug, S.M. Seutter , A. Parkhomovsky , A.M. Dabiran, and P energy elec- tron diffraction (RHEED) observations of unipolar films grown on bulk GaN{0001} and compare

  17. High linearity GaN HEMT power amplifier with pre-linearization gate diode Shouxuan Xie, Vamsi Paidi, Sten Heikman, Alessandro Chini,

    E-Print Network [OSTI]

    Rodwell, Mark J. W.

    High linearity GaN HEMT power amplifier with pre-linearization gate diode Shouxuan Xie, Vamsi Paidi Santa Barbara, CA 93106, USA A high linearity MMIC RF power amplifier is reported in the AlGaN/GaN HEMT to compensate the non-linear effect caused by the nonlinear input capacitance Cgs of the GaN HEMT device

  18. High Power GaN Oscillators using Field-Plated HEMT Structure Hongtao Xu, Christopher Sanabria, Sten Heikman, Stacia Keller, Umesh K. Mishra, and Robert A.

    E-Print Network [OSTI]

    York, Robert A.

    High Power GaN Oscillators using Field-Plated HEMT Structure Hongtao Xu, Christopher Sanabria, Sten Engineering University of California, Santa Barbara, California 93106, USA Abstract -- 5 GHz MMIC GaN oscillators based on AlGaN/GaN HEMTs are presented. By using field-plated HEMT structures, both the output

  19. Intrafacet migration effects in InGaN/GaN structures grown on triangular GaN ridges studied by submicron beam x-ray diffraction

    E-Print Network [OSTI]

    Sirenko, Andrei

    Intrafacet migration effects in InGaN/GaN structures grown on triangular GaN ridges studied for x-ray diffraction and reciprocal space mapping of InGaN/GaN multiple-quantum-well MQW structures grown on the sidewalls of 10- m-wide triangular GaN ridges with 1-1.1 facets. Samples were produced

  20. Growth of single crystalline GaN thin films on Si,,111... substrates by high vacuum metalorganic chemical vapor deposition using a single

    E-Print Network [OSTI]

    Boo, Jin-Hyo

    Growth of single crystalline GaN thin films on Si,,111... substrates by high vacuum metalorganic; published 20 August 2004 Hexagonal GaN thin films were grown on Si 111 substrates using single molecular precursor of diethylazidogallium methylhydrazine adduct, (Et)2Ga N3)HzMe], with the objectives of reducing

  1. AlGaN/GaN HEMTs grown by Molecular Beam Epitaxy on sapphire, Sic, and HVPE GaN templates

    E-Print Network [OSTI]

    Manfra, Michael J.

    PS-4 AlGaN/GaN HEMTs grown by Molecular Beam Epitaxy on sapphire, Sic, and HVPE GaN templates Nils ABSTRACT Molecular Beam Epitaxy of GaN and related alloys is becoming a rival to the more established, and HVPE SI-GaN templates on sapphire. While sapphire and SI-Sic are established substrates for the growth

  2. Growth of cubic GaN on 3CSiC/Si (001) nanostructures R.M. Kemper a,n

    E-Print Network [OSTI]

    As, Donat Josef

    ) substrate. These anti-phase domains strongly influence the optimum growth of GaN layers in these regions are due to the lattice mismatch with the substrate. For c-GaN, 3CSiC is the preferred substrate of GaN on post shaped nanostructures and analyze the influence of substrate domains on the defect

  3. Phonons in sapphire Al2O3 substrate for ZnO and GaN H.W. Kunert a,, A.G.J. Machatine b

    E-Print Network [OSTI]

    Nabben, Reinhard

    Phonons in sapphire Al2O3 substrate for ZnO and GaN H.W. Kunert a,, A.G.J. Machatine b , A. Keywords: Phonons; Sapphire; Group theory; Time reversal; Zno; GaN 1. Introduction The lattice structure in semiconductor research enabled fabrication of GaN-based blued emitting diodes and laser devices[1,2]. Due

  4. 1282 IEEE ELECTRON DEVICE LETTERS, VOL. 33, NO. 9, SEPTEMBER 2012 Top-Gate GaN Thin-Film Transistors Based

    E-Print Network [OSTI]

    is to deposit high-quality GaN thin films using inexpensive substrate under low temper- ature. Recently1282 IEEE ELECTRON DEVICE LETTERS, VOL. 33, NO. 9, SEPTEMBER 2012 Top-Gate GaN Thin-Film Transistors Based on AlN/GaN Heterostructures Rongsheng Chen, Wei Zhou, Meng Zhang, and Hoi Sing Kwok Abstract

  5. Transmission Electron Microscopy Study of Nonpolar a-Plane GaN Grown by Pendeo-Epitaxy on (112_0) 4H-SiC

    E-Print Network [OSTI]

    Zakharov, D.N.; Liliental-Weber, Z.; Wagner, B.; Reitmeier, Z.J.; Preble, E.A.; Davis, R.F.

    2008-01-01T23:59:59.000Z

    pendeo-epitaxial GaN layer grown on (1120) 4H-SiC substrate.a-plane GaN layers grown on (1120) 4H-SiC substrate with AlNGaN layers grown by heteroepitaxial methods on different substrates

  6. ZrO2 gate dielectrics produced by ultraviolet ozone oxidation for GaN and AlGaN/GaN transistors

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    MOSCAP process ?ow: n-GaN substrate; Ohmic metallization andtion for a AlGaN/ GaN HEMT on a substrate which has a poorsapphire substrate, a well-passivated AlGaN/ GaN HEMT grown

  7. SHERPA Document SHERPA Document -Institutional Repositories: Staff and Skills Requirements

    E-Print Network [OSTI]

    Southampton, University of

    SHERPA Document SHERPA Document - Institutional Repositories: Staff and Skills Requirements Mary This document began in response to requests received by the core SHERPA team for examples of job descriptions and UKCORR members. This document will be revised annually (July/August) to reflect changing needs

  8. Madonne: Document Image Analysis Techniques for Cultural Heritage Documents

    E-Print Network [OSTI]

    Boyer, Edmond

    Madonne: Document Image Analysis Techniques for Cultural Heritage Documents Jean-Marc Ogier and Karl Tombre Abstract. This paper presents the Madonne project, a French initiative to use document image anal- ysis techniques for the purpose of preserving and exploiting heritage documents. 1

  9. Software documentation, Page 1, Printed 7/11/01 Documentation

    E-Print Network [OSTI]

    Sommerville, Ian

    Software documentation, Page 1, Printed 7/11/01 Software Documentation Ian Sommerville Lancaster University, UK #12;Software documentation, Page 2, Printed 7/11/01 Introduction All large software development projects, irrespective of application, generate a large amount of associated documentation

  10. SOFA 2 Documentation Table of contents

    E-Print Network [OSTI]

    SOFA 2 Documentation Table of contents 1 Overview...................................................................................................................... 2 2 Documentation............................................................................................................. 2 3 Other documentation and howtos

  11. Technology Innovation Program Guidelines and Documentation

    E-Print Network [OSTI]

    Magee, Joseph W.

    #12;Technology Innovation Program Guidelines and Documentation Requirements for Research Involving ............................................................................ 5 F. Required Documentation.............................................................................. 16 D. Required Documentation

  12. Selective area growth and characterization of GaN nanocolumns, with and without an InGaN insertion, on semi-polar (1122) 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); Zuiga-Perez, J.; Mierry, P. de [CRHEA-CNRS, 06560 Valbonne (France)] [CRHEA-CNRS, 06560 Valbonne (France); Trampert, A. [Paul-Drude-Institut fr Festkrperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)] [Paul-Drude-Institut fr Festkrperelektronik, 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 (1122) 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.

  13. Hazard baseline documentation

    SciTech Connect (OSTI)

    Not Available

    1994-08-01T23:59:59.000Z

    This DOE limited technical standard establishes uniform Office of Environmental Management (EM) guidance on hazards baseline documents that identify and control radiological and nonradiological hazards for all EM facilities. It provides a road map to the safety and health hazard identification and control requirements contained in the Department`s orders and provides EM guidance on the applicability and integration of these requirements. This includes a definition of four classes of facilities (nuclear, non-nuclear, radiological, and other industrial); the thresholds for facility hazard classification; and applicable safety and health hazard identification, controls, and documentation. The standard applies to the classification, development, review, and approval of hazard identification and control documentation for EM facilities.

  14. AlGaN/GaN field effect transistors for power electronicsEffect of finite GaN layer thickness on thermal characteristics

    SciTech Connect (OSTI)

    Hodges, C., E-mail: chris.hodges@bristol.ac.uk; Anaya Calvo, J.; Kuball, M. [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)] [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Stoffels, S.; Marcon, D. [IMEC, Kapeldreef 75, B3001 Leuven (Belgium)] [IMEC, Kapeldreef 75, B3001 Leuven (Belgium)

    2013-11-11T23:59:59.000Z

    AlGaN/GaN heterostructure field effect transistors with a 150?nm thick GaN channel within stacked Al{sub x}Ga{sub 1?x}N layers were investigated using Raman thermography. By fitting a thermal simulation to the measured temperatures, the thermal conductivity of the GaN channel was determined to be 60?W m{sup ?1} K{sup ?1}, over 50% less than typical GaN epilayers, causing an increased peak channel temperature. This agrees with a nanoscale model. A low thermal conductivity AlGaN buffer means the GaN spreads heat; its properties are important for device thermal characteristics. When designing power devices with thin GaN layers, as well as electrical considerations, the reduced channel thermal conductivity must be considered.

  15. Sandia Energy - SCADA Documents

    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: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol Home Distribution GridDocuments Home Stationary PowerResearchRiskRotorDocuments

  16. Document | Department of Energy

    Office of Environmental Management (EM)

    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 1,006 492 742 33 1112011AT&T,Office of Policy,Policy ActDetroit7471 Federal Register /Document Document

  17. Document | Department of Energy

    Office of Environmental Management (EM)

    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 1,006 492 742 33 1112011AT&T,Office of Policy,Policy ActDetroit7471 Federal Register /DocumentDocument

  18. Document | Department of Energy

    Office of Environmental Management (EM)

    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 1,006 492 742 33 1112011AT&T,Office of Policy,Policy ActDetroit7471 Federal Register /DocumentDocumentOHA

  19. Document | Department of Energy

    Office of Environmental Management (EM)

    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 1,006 492 742 33 1112011AT&T,Office of Policy,Policy ActDetroit7471 Federal RegisterDocument Document

  20. Document Control Program | The Ames Laboratory

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

    Training, Documents, & Records Document Control Program The Document Control (DC) Plan ensures that only approved, current versions of such documents are used in the workplace or...

  1. DOCUMENT MAPS FOR COMPETENCE MANAGEMENT

    E-Print Network [OSTI]

    Honkela, Timo

    DOCUMENT MAPS FOR COMPETENCE MANAGEMENT Timo Honkela Helsinki University of Technology Neural area of the document maps, i.e., competence management. The document map approach has approved The WEBSOM is a method for analyzing and visualizing large document col- lections. In the WEBSOM method

  2. Structural and energy characteristics of native vacancy-type defects in the biaxially stressed GaN lattice

    SciTech Connect (OSTI)

    Bez'yazychnaya, T. V.; Zelenkovskii, V. M.; Gurskii, A. L.; Ryabtsev, G. I. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)], E-mail: ryabtsev@dragon.bas-net.by

    2008-11-15T23:59:59.000Z

    For biaxially stressed GaN clusters, the structure, charges, and energies of the formation of intrinsic Ga and N vacancies are calculated by the quantum-chemical method in the SCF MO LCAO approximation taking into account relaxation of the crystalline surroundings. It is established that the use of substrates introducing compressive or tensile stresses into the epitaxial layer affects the concentrations of intrinsic vacancy-type point defects. This effect most clearly manifests itself in the nitrogen sublattice in the GaN crystal lattice, especially in the case of its tension, i.e., during the epitaxial grown of GaN on the Si substrate. Redistribution of the electron density in the defect region in the case of lattice compression or tension can be the cause of variation in the location of electronic levels of defects in the band gap of the crystal.

  3. CAPITAL ASSET DOCUMENT TRAINING

    E-Print Network [OSTI]

    KUALI CAPITAL ASSET MANAGEMENT DOCUMENT TRAINING Business and Financial Services, Property Management Presented by: Rachel Drenth #12;Sign On to the Training Site CSU CAP (Campus Administration://padroni.is.colostate.edu:7778/portal/page/portal/CAPQA (THEN CHOOSE QUAL 2) Non-production Applications: Training Kuali

  4. Virtual Gateway Network Documentation

    E-Print Network [OSTI]

    Segall, Adrian

    Virtual Gateway Network Documentation Composed By: Stiven Andre Nikolai Gukov #12;Table of contents.3) VGNET as a network manager 2) VGNET explained 2.1) One PC with multiple Internet access points. 2 both routers. 1.3) VGNET as a network manager Let's look at figure 3 again. The perfect scenario we may

  5. ENERGY REVIEW Consultation Document

    E-Print Network [OSTI]

    ENERGY REVIEW Consultation Document JANUARY 2006 Our Energy Challenge Securing clean, affordable energy for the long-term #12;Our Energy Challenge Securing clean, affordable energy for the long term #12;OUR ENERGY CHALLENGE SECURING CLEAN, AFFORDABLE ENERGY FOR THE LONG TERM ii Why is the government

  6. Computer-aided documentation

    SciTech Connect (OSTI)

    Rosenberg, S.

    1982-01-01T23:59:59.000Z

    Current standards for high-quality documentation of complex computer systems include many criteria, based on the application and user levels. Important points common to many systems are: targeting to specific user groups; being complete, concise, and structured; containing both tutorials and reference material; being field-tested; and being timely in appearance relative to the software delivery. To achieve these goals, uniform quality standards should be more vigorously applied, the documentation development cycle should be shortened, more documentation/software help should be available on line, and more user interaction should be solicited. For future computer systems, the proposal is made that the documentation be machine comprehensible. This should be phased in, with the immediate goal being to facilitate user querying for information, and with an ultimate goal of providing a database for programmer apprentice artificial-intelligence programs that assist software development. This new functionality will be the result of several trends, including the drastically reduced cost of read-only online random-access storage via video optical disks, the ongoing successes of artificial-intelligence programs when applied to limited application areas, and the ever increasing cost of software programmers. 3 references.

  7. Presidential Documents Federal Register

    E-Print Network [OSTI]

    Presidential Documents 3821 Federal Register Vol. 76, No. 14 Friday, January 21, 2011 Title 3, 1993. As stated in that Executive Order and to the extent permitted by law, each agency must, among, such as user fees or marketable permits, or providing information upon which choices can be made by the public

  8. Properties of radio-frequency-sputter-deposited GaN films in a nitrogen/hydrogen mixed gas

    SciTech Connect (OSTI)

    Miyazaki, Takayuki; Takada, Kouhei; Adachi, Sadao; Ohtsuka, Kohji [Department of Electronic Engineering, Faculty of Engineering, Gunma University, Kiryu-shi, Gunma 376-8515 (Japan); Research and Development Division, Sanken Electric Co., Ltd., Niiza-shi, Saitama 352-8666 (Japan)

    2005-05-01T23:59:59.000Z

    GaN films have been deposited by reactive sputtering in nitrogen gas at pressures from 0.08 to 2.70 Pa with and without the addition of hydrogen gas. X-ray diffraction (XRD), Fourier transform infrared (FTIR), optical absorption, and photoluminescence (PL) spectroscopy have been used to characterize the sputter-deposited GaN films. The XRD pattern reveals that the GaN films deposited in nitrogen gas at pressures lower than 0.53 Pa are polycrystals with the (0001) texture ({alpha}-GaN), while those deposited at or above 1.07 Pa display mixed crystalline orientations or an amorphous-like nature. The GaN:H films deposited in nitrogen/hydrogen mixed gas, on the other hand, show an amorphous or amorphous-like nature. The FTIR spectra indicate that the GaN:H films show peaks arising from hydrogen-related bonds at {approx}1000 and {approx}3200 cm{sup -1}, in addition to the GaN absorption band at {approx}555 cm{sup -1}. The optical absorption spectra at 300 K indicate the fundamental absorption edges at {approx}3.38 and {approx}3.7 eV for the highly oriented {alpha}-GaN and amorphous GaN:H films, respectively. PL emission has been observed from sputter-deposited {alpha}-GaN films at temperatures below 100 K. The GaN:H films also show strong band-edge and donor-acceptor pair emissions. The PL emission in the GaN:H film may arise from crystalline GaN particles embedded in the amorphous GaN matrix.

  9. Technical approach document

    SciTech Connect (OSTI)

    Not Available

    1989-12-01T23:59:59.000Z

    The Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978, Public Law 95-604 (PL95-604), grants the Secretary of Energy the authority and responsibility to perform such actions as are necessary to minimize radiation health hazards and other environmental hazards caused by inactive uranium mill sites. This Technical Approach Document (TAD) describes the general technical approaches and design criteria adopted by the US Department of Energy (DOE) in order to implement remedial action plans (RAPS) and final designs that comply with EPA standards. It does not address the technical approaches necessary for aquifer restoration at processing sites; a guidance document, currently in preparation, will describe aquifer restoration concerns and technical protocols. This document is a second revision to the original document issued in May 1986; the revision has been made in response to changes to the groundwater standards of 40 CFR 192, Subparts A--C, proposed by EPA as draft standards. New sections were added to define the design approaches and designs necessary to comply with the groundwater standards. These new sections are in addition to changes made throughout the document to reflect current procedures, especially in cover design, water resources protection, and alternate site selection; only minor revisions were made to some of the sections. Sections 3.0 is a new section defining the approach taken in the design of disposal cells; Section 4.0 has been revised to include design of vegetated covers; Section 8.0 discusses design approaches necessary for compliance with the groundwater standards; and Section 9.0 is a new section dealing with nonradiological hazardous constituents. 203 refs., 18 figs., 26 tabs.

  10. US Department of Energy (DOE)/Gosatomnadzor (GAN) of Russia project at the Petersburg Nuclear Physics Institute (PNPI)

    SciTech Connect (OSTI)

    Baranov, I.A.; Konoplev, K.A. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Hauser, G.C. [Sandia National Lab., Albuquerque, NM (United States)] [and others

    1997-08-01T23:59:59.000Z

    This paper presents a summary of work accomplished within the scope of the DOE-Gosatomnadzor (GAN) Agreement to reduce vulnerability to theft of direct-use nuclear materials in Russia. The DOE-GAN agreement concerns the Russian Academy of Science B.P. Konstantinov Petersburg Nuclear Physics Institute (PNPI), located 45 kilometers from St. Petersburg. The PNPI operates facilities to research basic nuclear physics. Current world conditions require particular attention to the issue of Material Protection, Control, and Accounting (MPC&A) of nuclear materials. The long-term plan to increase security at the facility is outlined, including training, physical protection upgrades, and material control and accountability. 4 figs.

  11. High temperature electron spin dynamics in bulk cubic GaN: Nanosecond spin lifetimes far above room-temperature

    SciTech Connect (OSTI)

    Bu, J. H.; Schaefer, A.; Hgele, D.; Rudolph, J. [Arbeitsgruppe Spektroskopie der kondensierten Materie, Ruhr-Universitt Bochum, Universittsstrae 150, D-44780 Bochum (Germany); Schupp, T.; As, D. J. [Department of Physics, University of Paderborn, Warburger Str. 100, D-33095 Paderborn (Germany)

    2014-11-03T23:59:59.000Z

    The electron spin dynamics in n-doped bulk cubic GaN is investigated for very high temperatures from 293?K up to 500?K by time-resolved Kerr-rotation spectroscopy. We find extraordinarily long spin lifetimes exceeding 1?ns at 500?K. The temperature dependence of the spin relaxation time is in qualitative agreement with predictions of Dyakonov-Perel theory, while the absolute experimental times are an order of magnitude shorter than predicted. Possible reasons for this discrepancy are discussed, including the role of phase mixtures of hexagonal and cubic GaN as well as the impact of localized carriers.

  12. Hydrogen effect on near-atmospheric nitrogen plasma assisted chemical vapor deposition of GaN film growth

    SciTech Connect (OSTI)

    Nagata, T.; Haemori, M.; Sakuma, Y.; Chikyow, T. [Advanced Electronic Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Anzai, J.; Uehara, T. [Sekisui Chemical Co., Ltd., Wadai, Tsukuba, Ibaraki 300-4292 (Japan)

    2009-03-15T23:59:59.000Z

    The effect of hydrogen on near-atmospheric nitrogen plasma and low temperature growth of GaN thin film was investigated. To investigate nitrogen plasma diluted with hydrogen, optical emission spectroscopy (OES) was employed. OES indicates that hydrogen enhances the generation of the nitrogen first positive system and first negative systems by providing an additional kinetic pathway. The plasma also decomposed triethylgallium and generated Ga ions even at room temperature. Using this plasma, GaN film grew on sapphire substrate epitaxially at growth temperatures of above 170 deg. C and crystallized at 55 deg. C.

  13. Nucleation of single GaN nanorods with diameters smaller than 35 nm by molecular beam epitaxy

    SciTech Connect (OSTI)

    Chen, Yen-Ting [Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan (China) [Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan (China); Department of Physics, Chemistry and Biology (IFM), Linkping University, S-58183 Linkping (Sweden); Araki, Tsutomu [Department of Electrical and Electronic Engineering, Ritsumeikan University, 525-8577 Shiga (Japan)] [Department of Electrical and Electronic Engineering, Ritsumeikan University, 525-8577 Shiga (Japan); Palisaitis, Justinas; Persson, Per O. .; Olof Holtz, Per; Birch, Jens [Department of Physics, Chemistry and Biology (IFM), Linkping University, S-58183 Linkping (Sweden)] [Department of Physics, Chemistry and Biology (IFM), Linkping University, S-58183 Linkping (Sweden); Chen, Li-Chyong [Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China)] [Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China); Chen, Kuei-Hsien [Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan (China) [Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan (China); Center for Condensed Matter Sciences, National Taiwan University, 10617 Taipei, Taiwan (China); Nanishi, Yasushi [Global Innovation Research Organization, Ritsumeikan University, 525-8577 Shiga (Japan)] [Global Innovation Research Organization, Ritsumeikan University, 525-8577 Shiga (Japan)

    2013-11-11T23:59:59.000Z

    Nucleation mechanism of catalyst-free GaN nanorod grown on Si(111) is investigated by the fabrication of uniform and narrow (<35 nm) nanorods without a pre-defined mask by molecular beam epitaxy. Direct evidences show that the nucleation of GaN nanorods stems from the sidewall of the underlying islands down to the Si(111) substrate, different from commonly reported ones on top of the island directly. Accordingly, the growth and density control of the nanorods is exploited by a narrow-pass approach that only narrow nanorod can be grown. The optimal size of surrounding non-nucleation area around single nanorod is estimated as 88 nm.

  14. NEWS AND VIEWS PERSPECTIVE

    E-Print Network [OSTI]

    Mahler, D. Luke

    NEWS AND VIEWS PERSPECTIVE Niche diversification follows key innovation in Antarctic fish radiation Oxford Street, Cambridge MA 02138, USA Antarctic notothenioid fishes provide a fascinating evolu- tionary diversification has occurred repeatedly and in parallel. Keywords: community ecology, fish, macroevolution, phylo

  15. Forward viewing OCT endomicroscopy

    E-Print Network [OSTI]

    Liang, Kaicheng

    2014-01-01T23:59:59.000Z

    A forward viewing fiber optic-based imaging probe device was designed and constructed for use with ultrahigh speed optical coherence tomography in the human gastrointestinal tract. The light source was a MEMS-VCSEL at 1300 ...

  16. Nanoscale size dependence parameters on lattice thermal conductivity of Wurtzite GaN nanowires

    SciTech Connect (OSTI)

    Mamand, S.M., E-mail: soran.mamand@univsul.net [Department of Physics, College of Science, University of Sulaimani, Sulaimanyah, Iraqi Kurdistan (Iraq); Omar, M.S. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)] [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Muhammad, A.J. [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq)] [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq)

    2012-05-15T23:59:59.000Z

    Graphical abstract: Temperature dependence of calculated lattice thermal conductivity of Wurtzite GaN nanowires. Highlights: Black-Right-Pointing-Pointer A modified Callaway model is used to calculate lattice thermal conductivity of Wurtzite GaN nanowires. Black-Right-Pointing-Pointer A direct method is used to calculate phonon group velocity for these nanowires. Black-Right-Pointing-Pointer 3-Gruneisen parameter, surface roughness, and dislocations are successfully investigated. Black-Right-Pointing-Pointer Dislocation densities are decreases with the decrease of wires diameter. -- Abstract: A detailed calculation of lattice thermal conductivity of freestanding Wurtzite GaN nanowires with diameter ranging from 97 to 160 nm in the temperature range 2-300 K, was performed using a modified Callaway model. Both longitudinal and transverse modes are taken into account explicitly in the model. A method is used to calculate the Debye and phonon group velocities for different nanowire diameters from their related melting points. Effect of Gruneisen parameter, surface roughness, and dislocations as structure dependent parameters are successfully used to correlate the calculated values of lattice thermal conductivity to that of the experimentally measured curves. It was observed that Gruneisen parameter will decrease with decreasing nanowire diameters. Scattering of phonons is assumed to be by nanowire boundaries, imperfections, dislocations, electrons, and other phonons via both normal and Umklapp processes. Phonon confinement and size effects as well as the role of dislocation in limiting thermal conductivity are investigated. At high temperatures and for dislocation densities greater than 10{sup 14} m{sup -2} the lattice thermal conductivity would be limited by dislocation density, but for dislocation densities less than 10{sup 14} m{sup -2}, lattice thermal conductivity would be independent of that.

  17. Lattice location of implanted $^{147}$Nd and $^{147*}$Pm in GaN using emission channeling

    E-Print Network [OSTI]

    De Vries, B; Vantomme, A; Correia, J G

    2003-01-01T23:59:59.000Z

    The lattice location of $^{147}$Nd and $^{147^{*}}$Pm in thin-film, single-crystalline hexagonal GaN was studied by means of the emission channeling technique. The angular emission yields of $\\beta^{-}$-particles and conversion electrons emitted by the radioactive isotopes $^{147}$Nd and $^{147^{*}}$Pm were measured using a position-sensitive detector following 60 keV room temperature implantation at a dose of 1 $\\times 10^{13}$ cm$^{-2}$ and annealing at 900C. The emission patterns around the [0001], [1102], [1101], and [2113] crystal axes give direct evidence that the majority (70%) of Nd and Pm atoms occupy substitutional Ga sites.

  18. Evaluation of GaN substrates grown in supercritical basic ammonia

    SciTech Connect (OSTI)

    Saito, Makoto; Yamada, Hisashi; Iso, Kenji; Sato, Hitoshi; Hirasawa, Hirohiko; Kamber, Derrick S.; Hashimoto, Tadao; Baars, Steven P. den; Speck, James S.; Nakamura, Shuji [Materials Department, University of California, Santa Barbara, California 93106 (United States)

    2009-02-02T23:59:59.000Z

    GaN crystals grown by the basic ammonothermal method were investigated for their use as substrates for device regrowth. X-ray diffraction analysis indicated that the substrates contained multiple grains while secondary ion mass spectroscopy (SIMS) revealed a high concentration of hydrogen, oxygen, and sodium. Despite these drawbacks, the emission from the light emitting diode structures grown by metal organic chemical vapor deposition on both the c-plane and m-plane epitaxial wafers was demonstrated. The SIMS depth profiles showed that the diffusion of the alkali metal from the substrate into the epitaxial film was small, especially in the m-direction.

  19. Metallicity of InN and GaN surfaces exposed to NH{sub 3}.

    SciTech Connect (OSTI)

    Walkosz, W.; Zapol, P.; Stephenson, G. B. (Materials Science Division)

    2012-01-01T23:59:59.000Z

    A systematic study of energies and structures of InN and GaN (0001) surfaces exposed to NH{sub 3} and its decomposition products was performed with first-principles methods. A phenomenological model including electron counting contributions is developed based on calculated DFT energies and is used to identify low-energy structures. These predictions are checked with additional DFT calculations. The equilibrium phase diagrams are found to contain structures that violate the electron counting rule. Densities of states for these structures indicate n-type conductivity, consistent with available experimental results.

  20. Time-resolved photoluminescence from defects in n-type GaN

    SciTech Connect (OSTI)

    Reshchikov, M. A., E-mail: mreshchi@vcu.edu [Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)

    2014-03-14T23:59:59.000Z

    Point defects in GaN were studied with time-resolved photoluminescence (PL). The effects of temperature and excitation intensity on defect-related PL have been investigated theoretically and experimentally. A phenomenological model, based on rate equations, explains the dependence of the PL intensity on excitation intensity, as well as the PL lifetime and its temperature dependence. We demonstrate that time-resolved PL measurements can be used to find the concentrations of free electrons and acceptors contributing to PL in n-type semiconductors.