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1

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

Science Conference Proceedings (OSTI)

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.

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

2

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

Science Conference Proceedings (OSTI)

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.

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

3

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

SciTech Connect

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

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

2012-07-15T23:59:59.000Z

4

Evolution of AlN buffer layers on Silicon and the effect on the property of the expitaxial GaN film  

E-Print Network (OSTI)

The morphology evolution of high-temperature grown AlN nucleation layers on (111) silicon has been studied using atomic force microscopy (AFM). The structure and morphology of subsequently grown GaN film were characterized ...

Zang, Keyan

5

Evaluation of GaN substrates grown in supercritical basic ammonia  

SciTech Connect

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.

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

6

Properties of In-Doped ZnO Films Grown by Metalorganic Chemical Vapor Deposition on GaN(0001) Templates  

E-Print Network (OSTI)

TCO is amor- phous indium tin oxide (ITO), most commonlythe properties of indium-doped zinc oxide layers grown byoxide, doping, n-type, MOCVD, metalorganic chemical vapor deposition, ZnO: In, indium

Ben-Yaacov, Tammy; Ive, Tommy; Walle, Chris G.; Mishra, Umesh K.; Speck, James S.; Denbaars, Steven P.

2010-01-01T23:59:59.000Z

7

As-grown deep-level defects in n-GaN grown by metal-organic chemical vapor deposition on freestanding GaN  

SciTech Connect

Traps of energy levels E{sub c}-0.26 and E{sub c}-0.61 eV have been identified as as-grown traps in n-GaN grown by metal-organic chemical vapor deposition by using deep level transient spectroscopy of the Schottky contacts fabricated by resistive evaporation. The additional traps of E{sub c}-0.13 and E{sub c}-0.65 eV have been observed in samples whose contacts are deposited by electron-beam evaporation. An increase in concentration of the E{sub c}-0.13 and E{sub c}-0.65 eV traps when approaching the interface between the contact and the GaN film supports our argument that these traps are induced by electron-beam irradiation. Conversely, the depth profiles of as-grown traps show different profiles between several samples with increased or uniform distribution in the near surface below 50 nm. Similar profiles are observed in GaN grown on a sapphire substrate. We conclude that the growth process causes these large concentrations of as-grown traps in the near-surface region. It is speculated that the finishing step in the growth process should be an essential issue in the investigation of the surface state of GaN.

Chen Shang; Ishikawa, Kenji; Hori, Masaru [Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Honda, Unhi; Shibata, Tatsunari; Matsumura, Toshiya; Tokuda, Yutaka [Aichi Institute of Technology, Yakusa, Toyota 470-0392 (Japan); Ueda, Hiroyuki; Uesugi, Tsutomu; Kachi, Tetsu [Toyota Central R and D Laboratories, Inc., Yokomichi, Nagakute 480-1192 (Japan)

2012-09-01T23:59:59.000Z

8

Impacts of anisotropic lattice relaxation on crystal mosaicity and luminescence spectra of m-plane Al{sub x}Ga{sub 1-x}N films grown on m-plane freestanding GaN substrates by NH{sub 3} source molecular beam epitaxy  

SciTech Connect

In-plane anisotropic lattice relaxation was correlated with the crystal mosaicity and luminescence spectra for m-plane Al{sub x}Ga{sub 1-x}N films grown on a freestanding GaN substrate by NH{sub 3}-source molecular beam epitaxy. The homoepitaxial GaN film exhibited A- and B-excitonic emissions at 8 K, which obeyed the polarization selection rules. For Al{sub x}Ga{sub 1-x}N overlayers, the m-plane tilt mosaic along c-axis was the same as the substrate as far as coherent growth was maintained (x{<=}0.25). However, it became more severe than along the a-axis for lattice-relaxed films (x{>=}0.52). The results are explained in terms of anisotropic lattice and thermal mismatches between the film and the substrate. Nonetheless, all the Al{sub x}Ga{sub 1-x}N films exhibited a near-band-edge emission peak and considerably weak deep emission at room temperature.

Hoshi, T.; Hazu, K.; Ohshita, K.; Kagaya, M.; Onuma, T.; Chichibu, S. F. [CANTech, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan); Fujito, K. [Optoelectronics Laboratory, Mitsubishi Chemical Corporation, 1000 Higashi-Mamiana, Ushiku 300-1295 (Japan); Namita, H. [Mitsubishi Chemical Group Science and Technology Research Center, Inc., 8-3-1 Chuo, Ami, Inashiki 300-0332 (Japan)

2009-02-16T23:59:59.000Z

9

Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy  

SciTech Connect

Low-temperature AlN buffer layers grown via plasma-assisted molecular beam epitaxy on Si (111) were found to significantly affect the subsequent growth morphology of GaN nanowires. The AlN buffer layers exhibited nanowire-like columnar protrusions, with their size, shape, and tilt determined by the AlN V/III flux ratio. GaN nanowires were frequently observed to adopt the structural characteristics of the underlying AlN columns, including the size and the degree of tilt. Piezoresponse force microscopy and polarity-sensitive etching indicate that the AlN films and the protruding columns have a mixed crystallographic polarity. Convergent beam electron diffraction indicates that GaN nanowires are Ga-polar, suggesting that Al-polar columns are nanowire nucleation sites for Ga-polar nanowires. GaN nanowires of low density could be grown on AlN buffers that were predominantly N-polar with isolated Al-polar columns, indicating a high growth rate for Ga-polar nanowires and suppressed growth of N-polar nanowires under typical growth conditions. AlN buffer layers grown under slightly N-rich conditions (V/III flux ratio = 1.0 to 1.3) were found to provide a favorable growth surface for low-density, coalescence-free nanowires.

Brubaker, Matt D. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); DARPA Center for Integrated Micro/Nano-Electromechanical Transducers (iMINT), University of Colorado, Boulder, Colorado 80309 (United States); Levin, Igor; Davydov, Albert V. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Rourke, Devin M.; Sanford, Norman A.; Bertness, Kris A. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Bright, Victor M. [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); DARPA Center for Integrated Micro/Nano-Electromechanical Transducers (iMINT), University of Colorado, Boulder, Colorado 80309 (United States)

2011-09-01T23:59:59.000Z

10

Characterization of Stress Relaxation, Dislocations and Crystallographic Tilt Via X-ray Microdiffraction in GaN (0001) Layers Grown by Maskless Pendeo-Epitaxy  

Science Conference Proceedings (OSTI)

Intrinsic stresses due to lattice mismatch and high densities of threading dislocations and extrinsic stresses resulting from the mismatch in the coefficients of thermal expansion are present in almost all III-Nitride heterostructures. Stress relaxation in the GaN layers occurs in conventional and in pendeo-epitaxial films via the formation of additional misfit dislocations, domain boundaries, elastic strain and wing tilt. Polychromatic X-ray microdiffraction, high resolution monochromatic X-ray diffraction and finite element simulations have been used to determine the distribution of strain, dislocations, sub-boundaries and crystallographic wing tilt in uncoalesced and coalesced GaN layers grown by maskless pendeo-epitaxy. An important parameter was the width-to-height ratio of the etched columns of GaN from which the lateral growth of the wings occurred. The strain and tilt across the stripes increased with the width-to-height ratio. Tilt boundaries formed in the uncoalesced GaN layers at the column/wing interfaces for samples with a large ratio. Sharper tilt boundaries were observed at the interfaces formed by the coalescence of two laterally growing wings. The wings tilted upward during cooling to room temperature for both the uncoalesced and the coalesced GaN layers. It was determined that finite element simulations that account for extrinsic stress relaxation can explain the experimental results for uncoalesced GaN layers. Relaxation of both extrinsic and intrinsic stress components in the coalesced GaN layers contribute to the observed wing tilt and the formation of sub-boundaries.

Barabash, R.I.; Ice, G.E.; Liu, W.; Einfeldt, S.; Hommel, D.; Roskowski, A.M.; Davis, R.F. (ORNL)

2010-06-25T23:59:59.000Z

11

Effects of growth temperature on Mg-doped GaN grown by ammonia molecular beam epitaxy  

SciTech Connect

The hole concentration p in Mg-doped GaN films grown by ammonia molecular beam epitaxy depends strongly on the growth temperature T{sub GR}. At T{sub GR}=760 Degree-Sign C, GaN:Mg films showed a hole concentration of p=1.2 Multiplication-Sign 10{sup 18} cm{sup -3} for [Mg]=4.5 Multiplication-Sign 10{sup 19} cm{sup -3}, while at T{sub GR}=840 Degree-Sign C, p=4.4 Multiplication-Sign 10{sup 16} cm{sup -3} for [Mg]=7 Multiplication-Sign 10{sup 19} cm{sup -3}. Post-growth annealing did not increase p. The sample grown at 760 Degree-Sign C exhibited a low resistivity of 0.7 {Omega}cm. The mobility for all the samples was around 3-7 cm{sup 2}/V s. Temperature-dependent Hall measurements and secondary ion mass spectroscopy suggest that the samples grown at T{sub GR}>760 Degree-Sign C are compensated by an intrinsic donor rather than hydrogen.

Hurni, Christophe A.; Lang, Jordan R.; Burke, Peter G.; Speck, James S. [Materials Department, University of California, Santa Barbara, 93106-5050 California (United States)

2012-09-03T23:59:59.000Z

12

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

Science Conference Proceedings (OSTI)

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 (electron mobility transistors.

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

13

High electron mobility through the edge states in random networks of c-axis oriented wedge-shaped GaN nanowalls grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Transport and optical properties of random networks of c-axis oriented wedge-shaped GaN nanowalls grown spontaneously on c-plane sapphire substrates through molecular beam epitaxy are investigated. Our study suggests a one dimensional confinement of carriers at the top edges of these connected nanowalls, which results in a blue shift of the band edge luminescence, a reduction of the exciton-phonon coupling, and an enhancement of the exciton binding energy. Not only that, the yellow luminescence in these samples is found to be completely suppressed even at room temperature. All these changes are highly desirable for the enhancement of the luminescence efficiency of the material. More interestingly, the electron mobility through the network is found to be significantly higher than that is typically observed for GaN epitaxial films. This dramatic improvement is attributed to the transport of electrons through the edge states formed at the top edges of the nanowalls.

Bhasker, H. P.; Dhar, S.; Sain, A. [Physics Department, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Kesaria, Manoj; Shivaprasad, S. M. [International Centre for Material Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

2012-09-24T23:59:59.000Z

14

Cubic GaN Light Emitting Diode Grown by Metalorganic Vapor-Phase Epitaxy  

E-Print Network (OSTI)

this paper, we report on the doping characteristics of Si and Mg in the growth of cubic GaN by metalorganic vapor-phase epitaxy (MOVPE). We also report the growth of a p-n diode structure made of cubic GaN, and its characterization by electron-beam-induced-current (EBIC) and current injection measurements.

Hidenao Tanaka Member; Vapor-phase Epitaxy; Atsushi Nakadaira

2000-01-01T23:59:59.000Z

15

Deep traps in nonpolar m-plane GaN grown by ammonia-based molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Deep level defects in nonpolar m-plane GaN grown by ammonia-based molecular beam epitaxy were characterized using deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) and compared with polar c-plane GaN that was grown simultaneously in the same growth run. Significant differences in both the levels present and their concentrations were observed upon comparison of both growth orientations. DLTS revealed electron traps with activation energies of 0.14 eV, 0.20 eV, and 0.66 eV in the m-plane material, with concentrations that were {approx}10-50 x higher than traps of similar activation energies in the c-plane material. Likewise, DLOS measurements showed {approx}20 x higher concentrations of both a C{sub N} acceptor-like state at E{sub C} - 3.26 eV, which correlates with a high background carbon concentration observed by secondary ion mass spectroscopy for the m-plane material [A. Armstrong, A. R. Arehart, B. Moran, S. P. DenBaars, U. K. Mishra, J. S. Speck, and S. A. Ringel, Appl. Phys. Lett. 84, 374 (2004)], and the V{sub Ga}-related state level at E{sub C} - 2.49 eV, which is consistent with an enhanced yellow luminescence observed by photoluminescence. The findings suggest a strong impact of growth dynamics on the incorporation of impurities and electrically active native point defects as a function of GaN growth plane polarity.

Zhang, Z.; Arehart, A. R. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Hurni, C. A.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106-5050 (United States); Yang, J. [Department of Materials Science and Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Myers, R. C.; Ringel, S. A. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, Ohio State University, Columbus, Ohio 43210 (United States)

2012-01-30T23:59:59.000Z

16

Structural and optical studies of GaN pn-junction with AlN buffer layer grown on Si (111) by RF plasma enhanced MBE  

Science Conference Proceedings (OSTI)

GaN pn-junction grown on silicon substrates have been the focus in a number of recent reports and further effort is still necessary to improve its crystalline quality for practical applications. GaN has the high n-type background carrier concentration resulting from native defects commonly thought to be nitrogen vacancies. In this work, we present the growth of pn-junction of GaN on Si (111) substrate using RF plasma-enhanced molecular beam epitaxy (MBE). Both of the layers show uniformity with an average thickness of 0.709 {mu}m and 0.095 {mu}m for GaN and AlN layers, respectively. The XRD spectra indicate that no sign of cubic phase of GaN are found, so it is confirmed that the sample possessed hexagonal structure. It was found that all the allowed Raman optical phonon modes of GaN, i.e. the E2 (low), E1 (high) and A1 (LO) are clearly visible.

Yusoff, Mohd Zaki Mohd; Hassan, Zainuriah; Woei, Chin Che; Hassan, Haslan Abu; Abdullah, Mat Johar [Nano-Optoelectronics Research and Technology Laboratory School of Physics, Universiti Sains Malaysia, 11800 Penang, Malaysia and Department of Applied Sciences Universiti Teknologi MARA (UiTM) 13500 Permatang Pauh, Penang (Malaysia); Department of Applied Sciences Universiti Teknologi MARA (UiTM) 13500 Permatang Pauh, Penang (Malaysia)

2012-06-29T23:59:59.000Z

17

Characterization of GaN nanowires grown on PSi, PZnO and PGaN on Si (111) substrates by thermal evaporation  

Science Conference Proceedings (OSTI)

In this research, we used an easy and inexpensive method to synthesize highly crystalline GaN nanowires (NWs); on different substrates such as porous silicon (PSi), porous zinc oxide (PZnO) and porous gallium nitride (PGaN) on Si (111) wafer by thermal evaporation using commercial GaN powder without any catalyst. Micro structural studies by scanning electron microscopy and transmission electron microscope measurements reveal the role of different substrates in the morphology, nucleation and alignment of the GaN nanowires. The degree of alignment of the synthesized nanowires does not depend on the lattice mismatch between wires and their substrates. Further structural and optical characterizations were performed using high resolution X-ray diffraction and energy-dispersive X-ray spectroscopy. Results indicate that the nanowires are of single-crystal hexagonal GaN. The quality and density of grown GaN nanowires for different substrates are highly dependent on the lattice mismatch between the nanowires and their substrates and also on the size of the porosity of the substrates. Nanowires grown on PGaN have the best quality and highest density as compared to nanowires on other substrates. By using three kinds of porous substrates, we are able to study the increase in the alignment and density of the nanowires.

Shekari, Leila; Hassan, Haslan Abu; Thahab, Sabah M.; Hassan, Zainuriah [Nano-Optoelectronics Research and Technology Laboratory School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Materials Engineering Department, College of Engineering, University of Kufa, Najaf (Iraq); Nano-Optoelectronics Research and Technology Laboratory School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia)

2012-06-20T23:59:59.000Z

18

Mg doping of GaN grown by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions  

SciTech Connect

Acceptor doping of GaN with Mg during plasma-assisted molecular beam epitaxy, under N-rich conditions and a relatively high growth temperature of 740 deg. C, was investigated. The p-doping level steadily increases with increasing Mg flux. The highest doping level achieved, determined from Hall measurements, is 2.1x10{sup 18} cm{sup -3}. The corresponding doping efficiency and hole mobility are approx4.9% and 3.7 cm{sup 2}/V s at room temperature. Cross-sectional transmission electron microscopy and photoluminescence measurements confirm good crystalline and optical quality of the Mg-doped layers. An InGaN/GaN quantum dot light emitting diode (lambda{sub peak}=529 nm) with p-GaN contact layers grown under N-rich condition exhibits a low series resistance of 9.8 OMEGA.

Zhang Meng; Bhattacharya, Pallab; Guo Wei; Banerjee, Animesh [Department of Electrical Engineering and Computer Science, Solid-State Electronics Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2010-03-29T23:59:59.000Z

19

Effect of gas feeding methods on optical properties of GaN grown by rapid thermal chemical vapor deposition reactor  

Science Conference Proceedings (OSTI)

Keywords: Ga vacancies, GaN growth, gas feeding method, optical property, rapid thermal chemical vapor deposition (RTCVD), yellow luminescence

Sun Jung Kim; Young Hun Seo; Kee Suk Nahm; Yun Bong Hahn; Hyun Wook Shim; Eun-Kyung Suh; Kee Young Lim; Hyung Jae Lee

1999-08-01T23:59:59.000Z

20

Synthesis and characterization of GaN thin films deposited on different substrates using a low-cost electrochemical deposition technique  

Science Conference Proceedings (OSTI)

Gallium nitride GaN thin films were deposited on three different substrates; Si (111), Si (100) and ITO coated glass using electrochemical deposition technique at 20 Degree-Sign C. A mixture of gallium nitrate, ammonium nitrate was used as electrolyte. The deposited films were investigated at room temperature by a series of material characterization techniques, namely; scanning electron microscopy (SEM), EDX and X-ray diffraction (XRD). SEM images and EDX results indicated that the growth of GaN films varies according to the substrates. XRD analyses showed the presence of hexagonal wurtzite and cubic zinc blende GaN phases with the crystallite size around 18-29 nm.

Al-Heuseen, K.; Hashim, M. R. [Al-Balqa Applied University, Ajloun University College (Jordan); School of Physics, Universiti Sains Malaysia, 11800-Penang (Malaysia)

2012-09-06T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Method of growing GaN films with a low density of structural defects using an interlayer  

DOE Patents (OSTI)

A dramatic reduction of the dislocation density in GaN was obtained by insertion of a single thin interlayer grown at an intermediate temperature (IT-IL) after the growth of an initial grown at high temperature. A description of the growth process is presented with characterization results aimed at understanding the mechanisms of reduction in dislocation density. A large percentage of the threading dislocations present in the first GaN epilayer are found to bend near the interlayer and do not propagate into the top layer which grows at higher temperature in a lateral growth mode. TEM studies show that the mechanisms of dislocation reduction are similar to those described for the epitaxial lateral overgrowth process, however a notable difference is the absence of coalescence boundaries.

Bourret-Courchesne, Edith D. (Richmond, CA)

2003-01-01T23:59:59.000Z

22

Polarized Emission from Single GaN Quantum Dots Grown by Molecular Beam Epitaxy  

Science Conference Proceedings (OSTI)

Polarization resolved microphotoluminescence measurements of single MBE-grown GaN/Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as dots, resulting in different built-in electric field. Moreover, a strongly linearly polarized emission is observed for the investigated dots with a degree of linear polarization of about 0.9, interpreted as the valence-band mixing induced by in-plane anisotropy due to strain and/or QD shape.

Amloy, S. [Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, S-58183 Linkoeping (Sweden); Department of Physics, Faculty of Science, Thaksin University, 93110 Phattalung (Thailand); Yu, K. H.; Karlsson, K. F.; Holtz, P. O. [Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, S-58183 Linkoeping (Sweden); Farivar, R.; Andersson, T. G. [Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-41296 Goeteborg (Sweden)

2011-12-23T23:59:59.000Z

23

Morphology in electrochemically grown conducting polymer films  

DOE Patents (OSTI)

A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol. 2 figs.

Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

1992-04-28T23:59:59.000Z

24

Photoconduction efficiencies and dynamics in GaN nanowires grown by chemical vapor deposition and molecular beam epitaxy: A comparison study  

Science Conference Proceedings (OSTI)

The normalized gains, which determines the intrinsic photoconduction (PC) efficiencies, have been defined and compared for the gallium nitride (GaN) nanowires (NWs) grown by chemical vapor deposition (CVD) and molecular beam epitaxy (MBE). By excluding the contributions of experimental parameters and under the same light intensity, the CVD-grown GaN NWs exhibit the normalized gain which is near two orders of magnitude higher than that of the MBE-ones. The temperature-dependent time-resolved photocurrent measurement further indicates that the higher photoconduction efficiency in the CVD-GaN NWs is originated from the longer carrier lifetime induced by the higher barrier height ({phi}{sub B} = 160 {+-} 30 mV) of surface band bending. In addition, the experimentally estimated barrier height at 20 {+-} 2 mV for the MBE-GaN NWs, which is much lower than the theoretical value, is inferred to be resulted from the lower density of charged surface states on the non-polar side walls.

Chen, R. S. [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Tsai, H. Y. [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Huang, Y. S. [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Chen, Y. T. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Chen, L. C. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China); Chen, K. H. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China)

2012-09-10T23:59:59.000Z

25

Influence of V/III growth flux ratio on trap states in m-plane GaN grown by ammonia-based molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) were utilized to investigate the behavior of deep states in m-plane, n-type GaN grown by ammonia-based molecular beam epitaxy (NH{sub 3}-MBE) as a function of systematically varied V/III growth flux ratios. Levels were detected at E{sub C} - 0.14 eV, E{sub C} - 0.21 eV, E{sub C} - 0.26 eV, E{sub C} - 0.62 eV, E{sub C} - 0.67 eV, E{sub C} - 2.65 eV, and E{sub C} - 3.31 eV, with the concentrations of several traps exhibiting systematic dependencies on V/III ratio. The DLTS spectra are dominated by traps at E{sub C} - 0.14 eV and E{sub C} - 0.67 eV, whose concentrations decreased monotonically with increasing V/III ratio and decreasing oxygen impurity concentration, and by a trap at E{sub C} - 0.21 eV that revealed no dependence of its concentration on growth conditions, suggestive of different physical origins. Higher concentrations of deeper trap states detected by DLOS with activation energies of E{sub C} - 2.65 eV and E{sub C} - 3.31 eV in each sample did not display measureable sensitivity to the intentionally varied V/III ratio, necessitating further study on reducing these deep traps through growth optimization for maximizing material quality of NH{sub 3}-MBE grown m-plane GaN.

Zhang, Z.; Arehart, A. R. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Hurni, C. A.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106-5050 (United States); Ringel, S. A. [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States); Institute for Materials Research, Ohio State University, Columbus, Ohio 43210 (United States)

2012-10-08T23:59:59.000Z

26

GaN Nanopore Arrays: Fabrication and Characterization  

E-Print Network (OSTI)

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 ...

Wang, Yadong

27

Relaxation and critical strain for maximum In incorporation in AlInGaN on GaN grown by metal organic vapour phase epitaxy  

Science Conference Proceedings (OSTI)

Quaternary AlInGaN layers were grown on conventional GaN buffer layers on sapphire by metal organic vapour phase epitaxy at different surface temperatures and different reactor pressures with constant precursor flow conditions. A wide range in compositions within 30-62% Al, 5-29% In, and 23-53% Ga was covered, which leads to different strain states from high tensile to high compressive. From high-resolution x-ray diffraction and Rutherford backscattering spectrometry, we determined the compositions, strain states, and crystal quality of the AlInGaN layers. Atomic force microscopy measurements were performed to characterize the surface morphology. A critical strain value for maximum In incorporation near the AlInGaN/GaN interface is presented. For compressively strained layers, In incorporation is limited at the interface as residual strain cannot exceed an empirical critical value of about 1.1%. Relaxation occurs at about 15 nm thickness accompanied by strong In pulling. Tensile strained layers can be grown pseudomorphically up to 70 nm at a strain state of 0.96%. A model for relaxation in compressively strained AlInGaN with virtual discrete sub-layers, which illustrates the gradually changing lattice constant during stress reduction is presented.

Reuters, Benjamin; Finken, M.; Wille, A.; Kalisch, H.; Vescan, A. [RWTH Aachen University, GaN Device Technology, Sommerfeldstrasse 24, 52074 Aachen (Germany); Juelich Aachen Research Alliance, JARA-FIT, Wilhelm-Johnen-Strasse, 52428 Juelich (Germany); Hollaender, B. [Juelich Aachen Research Alliance, JARA-FIT, Wilhelm-Johnen-Strasse, 52428 Juelich (Germany); Forschungszentrum Juelich GmbH, PGI9-IT, 52425 Juelich (Germany); Heuken, M. [RWTH Aachen University, GaN Device Technology, Sommerfeldstrasse 24, 52074 Aachen (Germany); AIXTRON SE, Kaiserstr. 98, 52134 Herzogenrath (Germany)

2012-11-01T23:59:59.000Z

28

Low energy electron beam induced vacancy activation in GaN  

Science Conference Proceedings (OSTI)

Experimental evidence on low energy electron beam induced point defect activation in GaN grown by metal-organic vapor phase epitaxy (MOVPE) is presented. The GaN samples are irradiated with a 5-20 keV electron beam of a scanning electron microscope and investigated by photoluminescence and positron annihilation spectroscopy measurements. The degradation of the band-to-band luminescence of the irradiated GaN films is associated with the activation of point defects. The activated defects were identified as in-grown Ga-vacancies. We propose that MOVPE-GaN contains a significant concentration of passive V{sub Ga}-H{sub n} complexes that can be activated by H removal during low energy electron irradiation.

Nykaenen, H.; Suihkonen, S.; Sopanen, M. [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland); Kilanski, L. [Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto (Finland); Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/56, 02-668 Warsaw (Poland); Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto (Finland)

2012-03-19T23:59:59.000Z

29

Thermal carrier emission and nonradiative recombinations in nonpolar (Al,Ga)N/GaN quantum wells grown on bulk GaN  

Science Conference Proceedings (OSTI)

We investigate, via time-resolved photoluminescence, the temperature-dependence of charge carrier recombination mechanisms in nonpolar (Al,Ga)N/GaN single quantum wells (QWs) grown via molecular beam epitaxy on the a-facet of bulk GaN crystals. We study the influence of both QW width and barrier Al content on the dynamics of excitons in the 10-320 K range. We first show that the effective lifetime of QW excitons {tau} increases with temperature, which is evidence that nonradiative mechanisms do not play any significant role in the low-temperature range. The temperature range for increasing {tau} depends on the QW width and Al content in the (Al,Ga)N barriers. For higher temperatures, we observe a reduction in the QW emission lifetime combined with an increase in the decay time for excitons in the barriers, until both exciton populations get fully thermalized. Based on analysis of the ratio between barrier and QW emission intensities, we demonstrate that the main mechanism limiting the radiative efficiency in our set of samples is related to nonradiative recombination in the (Al,Ga)N barriers of charge carriers that have been thermally emitted from the QWs.

Corfdir, P.; Dussaigne, A.; Giraud, E.; Ganiere, J.-D.; Grandjean, N.; Deveaud-Pledran, B. [Institute of Condensed Matter Physics, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Teisseyre, H. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Institute of High Pressure Physics, Polish Academy of Sciences, 01-142 Warsaw (Poland); Suski, T.; Grzegory, I. [Institute of High Pressure Physics, Polish Academy of Sciences, 01-142 Warsaw (Poland); Lefebvre, P. [Laboratoire Charles Coulomb - UMR5221 - CNRS - Universite Montpellier 2, 34095 Montpellier (France)

2012-02-01T23:59:59.000Z

30

Residual stress stability in fiber textured stoichiometric AlN film grown using rf magnetron sputtering  

Science Conference Proceedings (OSTI)

The authors report on the stability of mechanical stress with aging and thermal cycling for columnar structured stoichiometric and homogeneous aluminum nitride thin films grown using radio frequency magnetron sputtering technique. The set of deposition parameters were optimized for the best possible orientation of crystallites in the c axis of compositionally stoichiometric films. The as-grown stress in the slightly nitrogen-rich film does not change when exposed to the atmosphere following deposition, while that in the nitrogen-deficient film, it changes due to oxidation. Additionally, the magnitude of as-grown stress has been found to depend on the substrate material in addition to the deposition parameters. The stress in the film grown on a Si(001) substrate was more tensile than in the film grown on a semi-insulating (si) GaAs(001) substrate for a given set of deposition parameters. Furthermore, the stress in the film grown on Si decreased with temperature, while that on si GaAs increased, indicating the thermally induced stress component to be the major component in the residual stress. Upon subsequent cooling the stress changes in both substrates followed the same path as of heating, thus exhibiting no hysteresis with thermal cycles between room temperature and 400 deg. C.

Sah, R. E.; Kirste, L.; Baeumler, M.; Hiesinger, P.; Cimalla, V.; Lebedev, V.; Baumann, H.; Zschau, H.-E. [Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany); Institut fuer Kernphysik, J. Goethe Universitaet, Max-von-Lauer-Str. 1, 60438 Frankfurt/M (Germany); DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, 60486 Frankfurt/M (Germany)

2010-05-15T23:59:59.000Z

31

Mechanism of Charge Transport in Cobalt and Iron Phthalocyanine Thin Films Grown by Molecular Beam Epitaxy  

Science Conference Proceedings (OSTI)

Cobalt phthalocyanine (CoPc), iron phthalocyanine (FePc) and their composite (CoPc-FePc) films have been grown by molecular beam epitaxy (MBE). Grazing incidence X-ray diffraction (GIXRD) and scanning electron microscope (SEM) studies showed that composite films has better structural ordering compared to individual CoPc and FePc films. The temperature dependence of resistivity (in the temperature range 25 K- 100 K) showed that composite films are metallic, while individual CoPc and FePc films are in the critical regime of metal-to-insulator (M-I) transition The composite films show very high mobility of 110 cm{sup 2} V{sup -1} s{sup -1} at room temperature i.e. nearly two order of magnitude higher compared to pure CoPc and FePc films.

Kumar, Arvind; Samanta, Soumen; Singh, Ajay; Debnath, A. K.; Aswal, D. K.; Gupta, S. K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2011-12-12T23:59:59.000Z

32

Improved morphology in electrochemically grown conducting polymer films  

DOE Patents (OSTI)

A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

1990-12-31T23:59:59.000Z

33

Bi-Sr-Ca-Cu-O thin films grown by flash evaporation and pulsed laser deposition  

E-Print Network (OSTI)

Bismuth-Strontium-Calcium-Copper-Oxide (BSCCO) compounds are an important family of compounds that have one of the highest transition temperatures among all high-temperature superconductors. The compound is known to exist in three distinct phases, commonly referred to as the 2201, 2212 and 2223 phases. Of these three phases, the 2212 and 2223 phases are the most important, as their transition temperature is higher than the boiling point of liquid nitrogen. It is desirable to produce the compound in thin film form, as the bulk samples are normally polycrystalline. This thesis compares thin films produced by two techniques for depositing BSCCO in order to understand the effect of various processing parameters on the final quality of the thin films. Thin films were grown by flash evaporation at Texas A&M University, and by pulsed laser deposition (PLD) at the University of Wollongong, Australia. The latter of these techniques is widely used for growing thin films of various compounds. Single-phase 2212 films were grown on a MgO substrate using the pulsed laser deposition technique from commercially available 2212 powder. The effect of annealing on the thin films was also studied.

Ganapathy Subramanian, Santhana

2003-12-01T23:59:59.000Z

34

Step-flow anisotropy of the m-plane GaN (1100) grown under nitrogen-rich conditions by plasma-assisted molecular beam epitaxy  

Science Conference Proceedings (OSTI)

The homoepitaxial growth of m-plane (1100) GaN was investigated by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions. The surface morphologies as a function of sample miscut were studied, providing evidence for a strong growth anisotropy that is a consequence of the anisotropy of Ga adatom diffusion barriers on the m-plane surface recently calculated ab initio[Lymperakis and Neugebauer, Phys. Rev. B 79, 241308(R) (2009)]. We found that substrate miscut toward [0001] implies a step flow toward while substrate miscut toward [0001] causes formation of atomic steps either perpendicular or parallel to the [0001] direction, under N-rich conditions at 730 deg C. We describe the growth conditions for achieving atomically flat m-plane GaN layers with parallel atomic steps.

Sawicka, Marta; Siekacz, Marcin; Skierbiszewski, Czeslaw [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warszawa (Poland); TopGaN Ltd., Sokolowska 29/37, PL-01-142 Warszawa (Poland); Turski, Henryk; Krysko, Marcin; DziePcielewski, Igor; Grzegory, Izabella [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warszawa (Poland); Smalc-Koziorowska, Julita [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, PL-01-142 Warszawa (Poland); TopGaN Ltd., Sokolowska 29/37, PL-01-142 Warszawa (Poland); Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, PL-02-507 Warszawa (Poland)

2011-06-15T23:59:59.000Z

35

K8, HVPE Homoepitaxy of p-Type GaN on n-Type Catalyst Free ...  

Science Conference Proceedings (OSTI)

We present the growth of p-type HVPE GaN using catalyst free GaN nitride nanowires as a lattice matched substrate. The nanowires were grown using plasma ...

36

Intersubband Absorption at 1.55 ?M In Aln/Gan Multi Quantum Wells ...  

Science Conference Proceedings (OSTI)

Intersubband Absorption at 1.55 ?M In Aln/Gan Multi Quantum Wells Grown at 770 °C by Metal Organic Vapor Phase Epitaxy using Pulse Injection Method.

37

Fabrication and dielectric property of ferroelectric PLZT films grown on metal foils.  

SciTech Connect

We have grown ferroelectric Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) films on platinized silicon and LaNiO{sub 3}-buffered nickel substrates by chemical solution deposition using a sol-gel process based on acetic acid chemistry. The following measurements were obtained under zero-bias field: relative permittivity of {approx}960 and dielectric loss of {approx}0.04 on the PLZT film grown on Pt/Si substrates, and relative permittivity of {approx}820 and dielectric loss of {approx}0.06 on the PLZT film grown on LNO-buffered Ni substrates. In addition, a relative permittivity of 125 and dielectric loss of 0.02 were measured at room temperature under a high bias field of 1 x 10{sup 6} V/cm on PLZT deposited on LNO-buffered nickel substrate. Furthermore, a steady-state leakage current density of {approx}8.1 x 10{sup -9} A/cm{sup 2} and mean breakdown field strength of 1.7 x 10{sup 6} V/cm were measured at room temperature. Finally, remanent polarization (P{sub r}) of {approx} 2.0 x 10{sup -5} C/cm{sup 2}, coercive electric field (E{sub c}) of {approx}3.4 x 10{sup 4} V/cm, and energy density of {approx}45 J/cm{sup 3} were determined from room-temperature hysteresis loop measurements on PLZT/LNO/Ni film-on-foil capacitors with 250-{micro}m-diameter platinum top electrodes.

Ma, B.; Tong, S.; Narayanan, M.; Liu, S.; Chao, S.; Balachandran, U. (Energy Systems)

2011-07-01T23:59:59.000Z

38

Micro Raman Spectroscopy of Annealed Erbium Implanted GaN  

E-Print Network (OSTI)

Wurtzite GaN epilayers grown by metal organic chemical vapor deposition on sapphire substrates were subsequently ion implanted with Er to a dose of 5×10¹? cm?². The implanted samples were annealed in nitrogen atmosphere ...

Vajpeyi, Agam P.

39

Vertically aligned GaN nanotubes - Fabrication and current image analysis  

Science Conference Proceedings (OSTI)

In this work, we present a one step formation method of nanotubes on GaN film, and then map out local current of nanotubes. GaN nanotubes were formed by inductively coupled plasma (ICP) etching and found that tops of these nanotubes were hexagonal with ... Keywords: C-AFM, FESEM, GaN, ICP, Nanotubes

Shang-Chao Hung; Yan-Kuin Su; Shoou-Jinn Chang; Y. H. Chen

2006-11-01T23:59:59.000Z

40

Continuous spin reorientation transition in epitaxially grown antiferromagnetic NiO thin films  

SciTech Connect

Fe/NiO/MgO/Ag(001) films were grown epitaxially, and the Fe and NiO spin orientations were determined using x-ray magnetic dichroism. We find that the NiO spins are aligned perpendicularly to the in-plane Fe spins. Analyzing both the in-plane and out-of-plane spin components of the NiO layer, we demonstrate unambiguously that the antiferromagnetic NiO spins undergo a continuous spin reorientation transition from the in-plane to out-of-plane directions with increasing of the MgO thickness.

Li, J.; Arenholz, E.; Meng, Y.; Tan, A.; Park, J.; Jin, E.; Son, H.; Wu, J.; Jenkins, C. A.; Scholl, A.; Hwang, Chanyong; Qiu, Z. Q.

2011-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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41

Structural and magnetic properties of MBE grown GeMnN2 thin films  

Science Conference Proceedings (OSTI)

Epitaxial GeMnN{sub 2} thin films are synthesized by plasma-assisted molecular beam epitaxy. Transmission electron microscopy and x-ray diffraction measurements confirm that it is the orthorhombic variant, consistent with the predictions of first-principles calculations. The magnetic properties of the films are related to defects, with samples grown under Ge-rich conditions exhibiting a net magnetic moment above room temperature. These results are explained by first-principles calculations, indicating that the preferential substitution of one magnetic sublattice of GeMnN{sub 2} by impurities and/or intrinsic defects such as Ge antisites produces a net magnetic moment in an antiferromagnetic background, and also introduces spin-polarized carriers near the Fermi level.

Liu, Y [University of Wisconsin, Milwaukee; Lazarov, V. K. [University of Wisconsin, Milwaukee; Cheung, S.H. [University of Wisconsin, Milwaukee; Keavney, D.J. [Argonne National Laboratory (ANL); Gai, Zheng [ORNL; Gajdardziska-Josifovska, M [University of Wisconsin, Milwaukee; Weinert, M [University of Wisconsin, Milwaukee; Li, Lian [University of Wisconsin, Milwaukee

2012-01-01T23:59:59.000Z

42

Photoluminescence Characterization of ZnO Thin Films Grown by RF- Sputtering  

Science Conference Proceedings (OSTI)

This article presents photoluminescence (PL) characterization of ZnO thin films deposited by radio-frequency magnetron sputtering method on sapphire and n-type Si (100) substrates. PL measurements were carried out at room temperature to investigate the energy band gaps and optical quality of the ZnO thin films. In order to draw a specific picture of surface morphology of ZnO thin films, atomic force microscope images were taken. All the results were compared to the results obtained from the bulk ZnO sample. The results revealed that the energy band gap of ZnO thin films grown on n-type Si (100) is higher than ZnO on sapphire. However, energy band gap of bulk ZnO is higher compared to both ZnO on n-type Si (100) and sapphire (Al{sub 2}O{sub 3}). This is probably due to the crystalline quality because good crystallinity increases the radiation recombination and hence increase the intensity of the NBE emission.

Bakhori, S. K. Mohd; Ng, S. S.; Ahmad, M. A.; Ahmad, H.; Hassan, Z.; Hassan, H. Abu; Abdullah, M. J. [Nano-optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800, USM, Penang (Malaysia)

2011-03-30T23:59:59.000Z

43

Temperature dependence of mechanical stiffness and dissipation in ultrananocrystalline diamond films grown by the HFCVD techinque.  

SciTech Connect

We have characterized mechanical properties of ultrananocrystalline diamond (UNCD) thin films grown using the hot filament chemical vapor deposition (HFCVD) technique at 680 C, significantly lower than the conventional growth temperature of -800 C. The films have -4.3% sp{sup 2} content in the near-surface region as revealed by near edge x-ray absorption fine structure spectroscopy. The films, -1 {micro}m thick, exhibit a net residual compressive stress of 370 {+-} 1 MPa averaged over the entire 150 mm wafer. UNCD microcantilever resonator structures and overhanging ledges were fabricated using lithography, dry etching, and wet release techniques. Overhanging ledges of the films released from the substrate exhibited periodic undulations due to stress relaxation. This was used to determine a biaxial modulus of 838 {+-} 2 GPa. Resonant excitation and ring-down measurements in the kHz frequency range of the microcantilevers were conducted under ultrahigh vacuum (UHV) conditions in a customized UHV atomic force microscope system to determine Young's modulus as well as mechanical dissipation of cantilever structures at room temperature. Young's modulus is found to be 790 {+-} 30 GPa. Based on these measurements, Poisson's ratio is estimated to be 0.057 {+-} 0.038. The quality factors (Q) of these resonators ranged from 5000 to 16000. These Q values are lower than theoretically expected from the intrinsic properties of diamond. The results indicate that surface and bulk defects are the main contributors to the observed dissipation in UNCD resonators.

Adiga, V. P.; Sumant, A. V.; Suresh, S.; Gudeman, C.; Auciello, O.; Carlisle, J. A.; Carpick, R. W.; Materials Science Division; Univ. of Pennsylvania; Innovative Micro Tech.; Advanced Diamond Tech.

2009-06-01T23:59:59.000Z

44

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

E-Print Network (OSTI)

by Pendeo-Epitaxy on (1120) 4H-SiC. D.N. Zakharov 1 , Z.phase epitaxy on (1120) 4H-SiC substrates with AlN bufferPE layers were grown on 4H- SiC (1120) substrates previously

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

2008-01-01T23:59:59.000Z

45

High electron mobility in Ga(In)NAs films grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

We report the highest mobility values above 2000 cm{sup 2}/Vs in Si doped GaNAs film grown by molecular beam epitaxy. To understand the feature of the origin which limits the electron mobility in GaNAs, temperature dependences of mobility were measured for high mobility GaNAs and referential low mobility GaInNAs. Temperature dependent mobility for high mobility GaNAs is similar to the GaAs case, while that for low mobility GaInNAs shows large decrease in lower temperature region. The electron mobility of high quality GaNAs can be explained by intrinsic limiting factor of random alloy scattering and extrinsic factor of ionized impurity scattering.

Miyashita, Naoya; Ahsan, Nazmul; Monirul Islam, Muhammad; Okada, Yoshitaka [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Inagaki, Makoto [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Aichi (Japan); Yamaguchi, Masafumi [Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Aichi (Japan)

2012-11-26T23:59:59.000Z

46

Characterization of Epitaxial Film Silicon Solar Cells Grown on Seeded Display Glass: Preprint  

DOE Green Energy (OSTI)

We report characterizations of epitaxial film crystal silicon (c-Si) solar cells with open-circuit voltages (Voc) above 560 mV. The 2-um absorber cells are grown by low-temperature (<750 degrees C) hot-wire CVD (HWCVD) on Corning EAGLE XG display glass coated with a layer-transferred (LT) Si seed. The high Voc is a result of low-defect epitaxial Si (epi-Si) growth and effective hydrogen passivation of defects. The quality of HWCVD epitaxial growth on seeded glass substrates depends on the crystallographic quality of the seed and the morphology of the epitaxial growth surface. Heterojunction devices consist of glass/c-Si LT seed/ epi n+ Si:P/epi n- Si:P/intrinsic a-Si:H/p+ a-Si:H/ITO. Similar devices grown on electronically 'dead' n+ wafers have given Voc {approx}630 mV and {approx}8% efficiency with no light trapping features. Here we study the effects of the seed surface polish on epi-Si quality, how hydrogenation influences the device character, and the dominant junction transport physics.

Young, D. L.; Grover, S.; Teplin, C.; Stradins, P.; LaSalvia, V.; Chuang, T. K.; Couillard, J. G.; Branz, H. M.

2012-06-01T23:59:59.000Z

47

Characterization of Epitaxial Film Silicon Solar Cells Grown on Seeded Display Glass: Preprint  

Science Conference Proceedings (OSTI)

We report characterizations of epitaxial film crystal silicon (c-Si) solar cells with open-circuit voltages (Voc) above 560 mV. The 2-um absorber cells are grown by low-temperature (EAGLE XG display glass coated with a layer-transferred (LT) Si seed. The high Voc is a result of low-defect epitaxial Si (epi-Si) growth and effective hydrogen passivation of defects. The quality of HWCVD epitaxial growth on seeded glass substrates depends on the crystallographic quality of the seed and the morphology of the epitaxial growth surface. Heterojunction devices consist of glass/c-Si LT seed/ epi n+ Si:P/epi n- Si:P/intrinsic a-Si:H/p+ a-Si:H/ITO. Similar devices grown on electronically 'dead' n+ wafers have given Voc {approx}630 mV and {approx}8% efficiency with no light trapping features. Here we study the effects of the seed surface polish on epi-Si quality, how hydrogenation influences the device character, and the dominant junction transport physics.

Young, D. L.; Grover, S.; Teplin, C.; Stradins, P.; LaSalvia, V.; Chuang, T. K.; Couillard, J. G.; Branz, H. M.

2012-06-01T23:59:59.000Z

48

Epitaxial strontium titanate films grown by atomic layer deposition on SrTiO{sub 3}-buffered Si(001) substrates  

SciTech Connect

Epitaxial strontium titanate (STO) films have been grown by atomic layer deposition (ALD) on Si(001) substrates with a thin STO buffer layer grown by molecular beam epitaxy (MBE). Four unit cells of STO grown by MBE serve as the surface template for ALD growth. The STO films grown by ALD are crystalline as-deposited with minimal, if any, amorphous SiO{sub x} layer at the STO-Si interface. The growth of STO was achieved using bis(triisopropylcyclopentadienyl)-strontium, titanium tetraisopropoxide, and water as the coreactants at a substrate temperature of 250 Degree-Sign C. In situ x-ray photoelectron spectroscopy (XPS) analysis revealed that the ALD process did not induce additional Si-O bonding at the STO-Si interface. Postdeposition XPS analysis also revealed sporadic carbon incorporation in the as-deposited films. However, annealing at a temperature of 250 Degree-Sign C for 30 min in moderate to high vacuum (10{sup -6}-10{sup -9} Torr) removed the carbon species. Higher annealing temperatures (>275 Degree-Sign C) gave rise to a small increase in Si-O bonding, as indicated by XPS, but no reduced Ti species were observed. X-ray diffraction revealed that the as-deposited STO films were c-axis oriented and fully crystalline. A rocking curve around the STO(002) reflection gave a full width at half maximum of 0.30 Degree-Sign {+-} 0.06 Degree-Sign for film thicknesses ranging from 5 to 25 nm. Cross-sectional transmission electron microscopy revealed that the STO films were continuous with conformal growth to the substrate and smooth interfaces between the ALD- and MBE-grown STO. Overall, the results indicate that thick, crystalline STO can be grown on Si(001) substrates by ALD with minimal formation of an amorphous SiO{sub x} layer using a four-unit-cell STO buffer layer grown by MBE to serve as the surface template.

McDaniel, Martin D.; Posadas, Agham; Ngo, Thong Q.; Dhamdhere, Ajit; Smith, David J.; Demkov, Alexander A.; Ekerdt, John G. [Department of Chemical Engineering, University of Texas at Austin, 1 University Station C0400, Austin, Texas 78712 (United States); Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, Texas 78712 (United States); Department of Chemical Engineering, University of Texas at Austin, 1 University Station C0400, Austin, Texas 78712 (United States); Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, Texas 78712 (United States); Department of Chemical Engineering, University of Texas at Austin, 1 University Station C0400, Austin, Texas 78712 (United States)

2013-01-15T23:59:59.000Z

49

Structural Properties Studies of Zinc Oxide Thin Film Grown on Silicon Carbide by Means of X-ray Diffraction Technique  

Science Conference Proceedings (OSTI)

In this work, the structural properties of the zinc oxide (ZnO) thin film on silicon carbide (6H-SiC) grown by radio frequency sputtering technique are investigated thoroughly by means of X-ray diffraction (XRD) technique. Both conventional XRD phase analysis and rocking curve measurements are carried out in order to determine the crystalline structure and the crystalline quality of the ZnO sample. From the phase analysis, intense peaks correspond to ZnO(002), iC(006) and their multiple reflections, i.e. ZnO(004) and SiC(0012) are observed. This result suggests that the ZnO thin film is in wurzite structure. Through the simulation of XRD rocking curve of the ZnO(002) peak, the lattice mismatch of 5.49% is obtained.

Ching, C. G.; Ng, S. S.; Hassan, Z.; Hassan, H. Abu; Al-Hardan, N. H.; Abdullah, M. J. [Nano-optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800, Penang (Malaysia)

2011-03-30T23:59:59.000Z

50

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

E-Print Network (OSTI)

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 ...

Zang, Keyan

51

Low-temperature grown graphene films by using molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Complete graphene film is prepared by depositing carbon atoms directly on Cu foils in a molecular beam epitaxy chamber at 300 Degree-Sign C. The Raman spectrum of the film has indicated that high-quality few-layer graphene is obtained. With back-gated transistor architecture, the characteristic current modulation of graphene transistors is observed. Following the similar growth procedure, graphitization is observed at room temperature, which is consistent with the molecular dynamics simulations of graphene growth.

Lin, Meng-Yu [Institute of Electronics, National Taiwan University, Taipei, Taiwan (China); Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Guo, Wei-Ching; Wang, Pro-Yao [Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, Taiwan (China); Wu, Meng-Hsun [College of Photonics, National Chiao-Tung University, Tainan, Taiwan (China); Liu, Te-Huan; Chang, Chien-Cheng [Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan (China); Pao, Chun-Wei; Lin, Shih-Yen [Research Center for Applied Sciences, Academia Sinica, Nankang, Taipei, Taiwan (China); Lee, Si-Chen [Institute of Electronics, National Taiwan University, Taipei, Taiwan (China)

2012-11-26T23:59:59.000Z

52

Influence of nitrogen background pressure on structure of niobium nitride films grown by pulsed laser deposition  

SciTech Connect

Depositions of niobium nitride thin films on Nb using pulsed laser deposition (PLD) with different nitrogen background pressures (10.7 to 66.7 Pa) have been performed. The effect of nitrogen pressure on NbN formation in this process was examined. The deposited films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), and energy dispersive X-ray (EDX) analysis. Hexagonal {beta}-Nb{sub 2}N and cubic {delta}-NbN phases resulted when growth was performed in low nitrogen background pressures. With an increase in nitrogen pressure, NbN films grew in single hexagonal {beta}-Nb{sub 2}N phase. The formation of the hexagonal texture during the film growth was studied. The c/a ratio of the hexagonal {beta}-Nb{sub 2}N unit cell parameter increases with increasing nitrogen pressure. Furthermore, the N:Nb ratio has a strong influence on the lattice parameter of the {delta}-NbN, where the highest value was achieved for this ratio was 1.19. It was found that increasing nitrogen background pressure leads to change in the phase structure of the NbN film. With increasing nitrogen pressure, the film structure changes from hexagonal to a mixed phase and then back to a hexagonal phase.

Ashraf H. Farha, Ali O. Er, Yüksel Ufuktepe, Ganapati Myneni, Hani E. Elsayed-Ali

2011-12-01T23:59:59.000Z

53

GaN: Defect and Device Issues  

SciTech Connect

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.

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

1998-11-09T23:59:59.000Z

54

High-T{sub c} and high-J{sub c} SmFeAs(O,F) films on fluoride substrates grown by molecular beam epitaxy  

SciTech Connect

Superconducting thin films of SmFeAs(O,F) were prepared by molecular beam epitaxy on fluoride substrates. In our process, F-free SmFeAsO films were grown first, and F was subsequently introduced to the films by diffusion from an overlayer of SmF{sub 3}. By this simple process, record high T{sub c}, namely, T{sub c}{sup on} (T{sub c}{sup end}) = 57.8 K (56.4 K) was obtained in a film on CaF{sub 2}. Furthermore, the films on CaF{sub 2} showed high critical current density over 1 MA/cm{sup 2} in the self-field at 5 K. The correlation between superconductivity and epitaxial strain in SmFeAs(O,F) films is discussed.

Ueda, Shinya; Takeda, Soichiro; Takano, Shiro; Naito, Michio [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); TRIP, Japan Science and Technology Agency (JST), Chiyoda, Tokyo 102-0075 (Japan); Yamamoto, Akiyasu [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2011-12-05T23:59:59.000Z

55

Photoluminescence associated with basal stacking faults in c-plane ZnO epitaxial film grown by atomic layer deposition  

Science Conference Proceedings (OSTI)

Basal plane stacking faults (BSFs) with density of {approx}1 x 10{sup 6} cm{sup -1} are identified as the dominant defect in the annealed ZnO thin films grown on c-plane sapphire by atomic layer deposition. The dominant peak centered at 3.321 eV in low-temperature photoluminescence measurements is attributed to the emission from the BSFs. The emission mechanism is considered to be the confined indirect excitons in the region of quantum-well-like structure formed by the BSFs. The observed energy shift of 19 meV with respect to the BSF-bounded exciton at low temperature may be caused by the localization effect associated with the coupling between BSF quantum wells.

Yang, S.; Kuo, C. C.; Hsieh, W. F. [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Liu, W.-R. [Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Lin, B. H. [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Hsu, H.-C. [Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Hsu, C.-H. [Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

2012-03-05T23:59:59.000Z

56

Unusual defects in silicon carbide thin films grown by multiple or interrupted growth technique  

Science Conference Proceedings (OSTI)

This paper discusses the growth and characterization of 3C-SiC films on Si (100) and (111) substrates using hexamethyldisilane (HMDS) as the source material in a resistance-heated furnace as well as the formation and microstructure of various types of ... Keywords: 3C-SiC, 3C-SiC nanowires, CVD, Defects, HMDS, Interrupted growth, Voids

A. Gupta; C. Jacob

2006-01-01T23:59:59.000Z

57

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 15, NO. 2, JUNE 2005 3321 Carbon-Doped MgB2 Thin Films Grown by Hybrid  

E-Print Network (OSTI)

Thin Films Grown by Hybrid Physical-Chemical Vapor Deposition A. V. Pogrebnyakov, J. M. Redwing, J. E-00-1-0294 and by the National Science Foundation (NSF) under Grant DMR-0306746 and Grant DMR-0103354. The work of J. M. Redwing. Redwing, V. Vaithyanathan, D. G. Schlom, and A. Soukiassian are with the Department of Materials Science

Eom, Chang Beom

58

Grain size dependent mechanical properties of nanocrystalline diamond films grown by hot-filament CVD  

DOE Green Energy (OSTI)

Nanocrystalline diamond (NCD) films with a thickness of {approx}6 {micro}m and with average grain sizes ranging from 60 to 9 nm were deposited on silicon wafers using a hot-filament chemical vapor deposition (HFCVD) process. These samples were then characterized with the goal to identify correlations between grain size, chemical composition and mechanical properties. The characterization reveals that our films are phase pure and exhibit a relatively smooth surface morphology. The levels of sp{sup 2}-bonded carbon and hydrogen impurities are low, and showed a systematic variation with the grain size. The hydrogen content increases with decreasing grain size, whereas the sp{sup 2} carbon content decreases with decreasing grain size. The material is weaker than single crystalline diamond, and both stiffness and hardness decrease with decreasing grain size. These trends suggest gradual changes of the nature of the grain boundaries, from graphitic in the case of the 60 nm grain size material to hydrogen terminated sp{sup 3} carbon for the 9 nm grain size material. The films exhibit low levels of internal stress and freestanding structures with a length of several centimeters could be fabricated without noticeable bending.

Wiora, M; Bruehne, K; Floeter, A; Gluche, P; Willey, T M; Kucheyev, S O; Van Buuren, A W; Hamza, A V; Biener, J; Fecht, H

2008-08-01T23:59:59.000Z

59

Stress-induced VO{sub 2} films with M2 monoclinic phase stable at room temperature grown by inductively coupled plasma-assisted reactive sputtering  

SciTech Connect

We report on growth of VO{sub 2} films with M2 monoclinic phase stable at room temperature under atmospheric pressure. The films were grown on quartz glass and Si substrates by using an inductively coupled plasma-assisted reactive sputtering method. XRD-sin{sup 2}{Psi} measurements revealed that the films with M2 phase are under compressive stress in contrast to tensile stress of films with M1 phase. Scanning electron microscopy observations revealed characteristic crystal grain aspects with formation of periodical twin structure of M2 phase. Structural phase transition from M2 to tetragonal phases, accompanied by a resistance change, was confirmed to occur as the temperature rises. Growth of VO{sub 2} films composed of M2 phase crystalline is of strong interest for clarifying nature of Mott transition of strongly correlated materials.

Okimura, Kunio; Watanabe, Tomo [School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Sakai, Joe [GREMAN, UMR 7347 CNRS, Universite Francois Rabelais de Tours, Parc de Grandmont 37200 Tours (France)

2012-04-01T23:59:59.000Z

60

Molecular beam epitaxy of InAlN lattice-matched to GaN with homogeneous composition using ammonia as nitrogen source  

Science Conference Proceedings (OSTI)

InAlN lattice-matched to GaN was grown by molecular beam epitaxy (MBE) using ammonia as the nitrogen source. The alloy composition, growth conditions, and strain coherence of the InAlN were verified by high resolution x-ray diffraction {omega}-2{theta} scans and reciprocal space maps. Scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy of the InAlN revealed the absence of lateral composition modulation that was observed in the films grown by plasma-assisted MBE. InAlN/AlN/GaN high electron mobility transistors with smooth surfaces were fabricated with electron mobilities exceeding 1600 cm{sup 2}/Vs and sheet resistances below 244 {Omega}/sq.

Wong, Man Hoi; Wu Feng; Hurni, Christophe A.; Choi, Soojeong; Speck, James S.; Mishra, Umesh K. [Department of Electrical and Computer Engineering and Materials Department, University of California, Santa Barbara, California 93106 (United States)

2012-02-13T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

p-Type ZnO Thin Films Grown by MOCVD  

DOE Green Energy (OSTI)

ZnO has demonstrated a possibility to be doped as a p-type by using nitrogen and other group-V elements. A high nitrogen doping concentration by metalorganic chemical vapor deposition (MOCVD) with nitric oxide (NO) gas has been achieved. However, the processing window for obtaining the p-type ZnO:N film is very narrow, and the hole concentration is typically low. Possible compensation and passivation effects have been studied. Hydrogen and carbon elements are detected by secondary-ion mass spectroscopy (SIMS). Considering the other experimental and modeling results, we believe that the impurities inadvertently incorporated with the zinc precursor could be compensating or passivating the nitrogen acceptor and result in the low hole concentration.

Li, X.; Asher, S. E.; Keyes, B. M.; Moutinho, H. R.; Luther, J.; Coutts, T. J.

2005-02-01T23:59:59.000Z

62

LaMnO3 thin films grown by using pulsed laser deposition and their simple recovery to a stoichiometric phase by annealing  

Science Conference Proceedings (OSTI)

We systematically investigated various physical properties of epitaxial LaMnO{sub 3} thin films fabricated on SrTiO{sub 3} substrate by using pulsed laser deposition. In particular, we observed drastic changes in their properties when the as-grown films were annealed in a reduced-oxygen atmosphere. Whereas the as-grown LaMnO{sub 3} film showed ferromagnetic and semiconducting properties with a small optical band gap, the LaMnO{sub 3} films annealed at temperature higher than 700 C showed antiferromagnetic and insulating properties with an enlarged band gap. The optical features also changed drastically, in that the optical transition peak shifted to a higher energy with additional fine structures. Such changes were made in a direction such that the LaMnO{sub 3} films were more stoichiometric, indicating that the stoichiometric phase could be recovered by simple annealing of the pulsed-laser-deposited films. Finally, possibilities of the polar catastrophe scenario at the interface between LaMnO{sub 3} and SrTiO{sub 3} are briefly discussed.

Choi, W. S. [Seoul National University; Jeong, D. W. [Seoul National University; Jang, S. Y. [Seoul National University; Marton, Zsolt [ORNL; Seo, Sung Seok A [ORNL; Lee, Ho Nyung [ORNL; Lee, Y. S. [Soongsil University, Korea

2011-01-01T23:59:59.000Z

63

Critical thickness of high structural quality SrTiO3 films grown on orthorhombic (101) DyScO3  

Science Conference Proceedings (OSTI)

Strained epitaxial SrTiO{sub 3} films were grown on orthorhombic (101) DyScO{sub 3} substrates by reactive molecular-beam epitaxy. The epitaxy of this substrate/film combination is cube on cube with a pseudocubic out-of-plane (001) orientation. The strain state and structural perfection of films with thicknesses ranging from 50 to 1000 {angstrom} were examined using x-ray scattering. The critical thickness at which misfit dislocations was introduced was between 350 and 500 {angstrom}. These films have the narrowest rocking curves (full width at half maximum) ever reported for any heteroepitaxial oxide film (0.0018{sup o}). Only a modest amount of relaxation is seen in films exceeding the critical thicknesses even after postdeposition annealing at 700{sup o}C in 1 atm of oxygen. The dependence of strain relaxation on crystallographic direction is attributed to the anisotropy of the substrate. These SrTiO{sub 3} films show structural quality more typical of semiconductors such as GaAs and silicon than perovskite materials; their structural relaxation behavior also shows similarity to that of compound semiconductor films.

Hawley, Marilyn E [Los Alamos National Laboratory; Biegalski, Michael D [ORNL; Schlom, Darrell G [CORNELL U.

2008-01-01T23:59:59.000Z

64

In situ studies of the effect of silicon on GaN growth modes.  

SciTech Connect

We present real-time X-ray scattering studies of the influence of silicon on the homoepitaxial growth mode of GaN grown by metal-organic vapor-phase epitaxy. Both annealing of Si-doped GaN and surface dosing of GaN with disilane are shown to change the mode of subsequent growth from step-flow to layer-by-layer. By comparing the growth behavior induced by doped layers which have been annealed to that induced by surface dosing, we extract an approximate diffusion coefficient for Si in GaN of 3.5 x 10{sup -18} cm{sup 2}/s at 810{sup o}C.

Munkholm, A.; Stephenson, G. B.; Eastman, J. A.; Auciello, O.; Murty, M. V. R.; Thompson, C.; Fini, P.; Speck, J. S.; DenBaars, S. P.; Northern Illinois Univ.; Univ. of California at Santa Barbara

2000-12-01T23:59:59.000Z

65

Properties of H, O and C in GaN  

DOE Green Energy (OSTI)

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.

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

1996-04-01T23:59:59.000Z

66

Effects of the oxygen precursor on the electrical and structural properties of HfO{sub 2} films grown by atomic layer deposition on Ge  

SciTech Connect

We report on the growth by atomic layer deposition of HfO{sub 2} films on HF-last treated Ge(001) substrates using HfCl{sub 4} as a Hf source and either O{sub 3} or H{sub 2}O as oxygen sources. The choice of the oxygen precursor strongly influences the structural, chemical, and electrical properties of the HfO{sub 2} films: Those grown using H{sub 2}O exhibit local epitaxial growth, a large amount of contaminants such as chlorine and carbon, and a large frequency dispersion of the capacitance-voltage (C-V) characteristics. Films grown using O{sub 3} are good insulators and exhibit well-shaped C-V curves with a minimum frequency dispersion of the accumulation capacitance. Moreover, they are smoother, less crystallized, and with a lower contaminant content than those grown using H{sub 2}O. However, the use of O{sub 3} leads to the formation of a 2 nm thick layer, possibly GeO{sub x}, at the HfO{sub 2}/Ge interface.

Spiga, S.; Wiemer, C.; Tallarida, G.; Scarel, G.; Ferrari, S.; Seguini, G.; Fanciulli, M. [Laboratorio Nazionale MDM-INFM, Via C. Olivetti 2, 20041 Agrate Brianza, MI (Italy)

2005-09-12T23:59:59.000Z

67

Growth, microstructure and electrical properties of sputter-deposited hafnium oxide (HfO2) thin films grown using HfO2 ceramic target  

Science Conference Proceedings (OSTI)

Hafnium oxide (HfO?) thin films have been made by radio-frequency (rf) magnetron-sputtering onto Si(100) substrates under varying growth temperature (Ts). HfO? ceramic target has been employed for sputtering while varying the Ts from room temperature to 500?C during deposition. The effect of Ts on the growth and microstructure of deposited HfO? films has been studied using grazing incidence x-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HR-SEM) coupled with energy dispersive x-ray spectrometry (EDS). The results indicate that the effect of Ts is significant on the growth, surface and interface structure, morphology and chemical composition of the HfO? films. Structural characterization indicates that the HfO? films grown at Ts200 ?C are nanocrystalline. An amorphous-to-crystalline transition occurs at Ts=200 ?C. Nanocrystalline HfO? films crystallized in a monoclinic structure with a (-111) orientation. XPS measurements indicated the high surface-chemical quality and stoichiometric nature of the grown HfO? films. An interface layer (IL) formation occurs due to reaction at the HfO?-Si interface for HfO? films deposited at Ts>200 ?C. The thickness of IL increases with increasing Ts. XPS and EDS at the HfO?-Si cross-section indicate the IL is a (Hf, Si)-O compound. The electrical characterization using capacitance-voltage measurements indicate that the dielectric constant decreases from 25 to 16 with increasing Ts.

Aguirre, B.; Vemuri, R. S.; Zubia, David; Engelhard, Mark H.; Shutthanandan, V.; Kamala Bharathi, K.; Ramana, Chintalapalle V.

2011-01-01T23:59:59.000Z

68

Influence of growth rate on the epitaxial orientation and crystalline quality of CeO2 thin films grown on Al2O3(0001)  

SciTech Connect

Growth rate-induced epitaxial orientations and crystalline quality of CeO2 thin films grown on Al2O3(0001) by oxygen plasma-assisted molecular beam epitaxy were studied using in-situ and ex-situ characterization techniques. CeO2 grows as three-dimensional (3-D) islands and two-dimensional (2-D) layers at growth rates of 1-7 Å/min, and ?9 Å/min, respectively. The formation of epitaxial CeO2(100) and CeO2(111) thin films occurs at growth rates of 1 Å/min and ? 9 Å/min, respectively. Glancing incidence x-ray diffraction (GIXRD) measurements have shown that the films grown at intermediate growth rates (2-7 Å/min) consist of polycrystalline CeO2 along with CeO2(100). The thin film grown at 1 Å/min exhibits six in-plane domains, characteristic of well-aligned CeO2(100) crystallites. The content of the poorly-aligned CeO2(100) crystallites increases with increasing growth rate from 2 Å/min to 7 Å/min, and three out of six in-plane domains gradually decrease and eventually disappear, as confirmed by XRD pole figures. At growth rates ?9 Å/min, CeO2(111) film with single in-plane domain was identified. The formation of CeO2(100) 3-D islands at growth rates of 1-7 Å/min is a kinetically driven process unlike at growth rates ?9 Å/min which result in an energetically and thermodynamically more stable CeO2(111) surface.

Nandasiri, Manjula I.; Nachimuthu, Ponnusamy; Varga, Tamas; Shutthanandan, V.; Jiang, Weilin; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai; Seal, Sudipta; Kayani, Asghar N.

2011-01-14T23:59:59.000Z

69

Structural TEM study of nonpolar a-plane gallium nitride grown on (112_0) 4H-SiC by organometallic vapor phase epitaxy  

E-Print Network (OSTI)

nitride grown on (1120) 4H-SiC by organometallic vapor phasea-plane GaN grown on a 4H-SiC substrate with an AlN buffergrown on (0001) Al 2 O 3 , 6H-SiC or free- standing GaN

Zakharov, Dmitri N.; Liliental-Weber, Zuzanna; Wagner, Brian; Reitmeier, Zachary J.; Preble, Edward A.; Davis, Robert F.

2005-01-01T23:59:59.000Z

70

Properties of molecular beam epitaxy grown Eu{sub x}(transition metal){sub y} films (transition metals: Mn, Cr)  

Science Conference Proceedings (OSTI)

The electronic and crystallographic structures, as well as the magnetic properties, of Eu{sub x}(transition metal){sub y} (transition metals: Mn, Cr) thin films grown by molecular beam epitaxy were studied. Relative changes of the Eu/Mn and Eu/Cr ratios derived from the XPS lines, as well as x-ray reflectivity, indicate mixing of the Eu/Mn and Eu/Cr layers. Valency transitions from Eu{sup 2+} to Eu{sup 3+} were observed in both systems for most studied stoichiometries. A transition to a magnetically ordered phase was observed at 15 K, 40 K, and 62 K for selected films in the Eu-Mn system, and at 50 K for the film with a Eu/Cr ratio of 0.5.

Balin, K. [A. Chelkowski Institute of Physics, University of Silesia, Katowice, 40-007 (Poland); Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 (United States); Nowak, A. [A. Chelkowski Institute of Physics, University of Silesia, Katowice, 40-007 (Poland); Laboratoire de Physique de l'Etat Condense, University du Maine, Le Mans Cedex, 72085 (France); Gibaud, A. [Laboratoire de Physique de l'Etat Condense, University du Maine, Le Mans Cedex, 72085 (France); Szade, J. [A. Chelkowski Institute of Physics, University of Silesia, Katowice, 40-007 (Poland); Celinski, Z. [Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, Colorado Springs, Colorado 80918 (United States)

2011-04-01T23:59:59.000Z

71

Atomic-layer-deposited Al2O3 and HfO2 on GaN: A comparative study on interfaces and electrical characteristics  

Science Conference Proceedings (OSTI)

Al"2O"3, HfO"2, and composite HfO"2/Al"2O"3 films were deposited on n-type GaN using atomic layer deposition (ALD). The interfacial layer of GaON and HfON was observed between HfO"2 and GaN, whereas the absence of an interfacial layer at Al"2O"3/GaN ... Keywords: Al2O3, Atomic-layer-deposition (ALD), GaN, HfO2, High k dielectric, MOS

Y. C. Chang; M. L. Huang; Y. H. Chang; Y. J. Lee; H. C. Chiu; J. Kwo; M. Hong

2011-07-01T23:59:59.000Z

72

LATE NEWS: KK3, Non-Catalytic Synthesis of GaN Nanostructures ...  

Science Conference Proceedings (OSTI)

We have observed the synthesis of gallium nitride (GaN) nanopowders on boron ... as 400°C. The synthesis process is based on the reaction between gallium atoms from the decomposition of gallium acetylacetonate and ammonia gas molecules. ... the crystal structure and growth mechanism of the grown nanostructures.

73

Linear surface smoothening of (Ti{sub 0.48}Al{sub 0.52})N thin films grown on rough substrates  

SciTech Connect

The evolution of surface roughness during the growth of sputter-deposited solid solution (Ti{sub 0.48}Al{sub 0.52})N films on rough high-speed-steel (HSS) substrates has been studied by atomic force microscopy. It has been revealed that the growing (Ti{sub 0.48}Al{sub 0.52})N/HSS film experiences a continuous surface smoothening. Scaling analyses along with surface power spectra calculation of the (Ti{sub 0.48}Al{sub 0.52})N films grown on smooth Si(100) substrates under the same deposition conditions indicate that this surface smoothening is linear and can be explained by a simple linear equation with surface diffusion as the smoothening mechanism and shot noise as the roughening effect. The observed linear surface smoothening in (Ti{sub 0.48}Al{sub 0.52})N/HSS films has also been confirmed by our numerical simulations of the film growth using real HSS and Si(100) substrates as their initial growth conditions and can be understood in terms of the competition between the surface-diffusion-induced decrease in substrate roughness contribution and the noise-driven roughening effect.

Liu, Z.-J.; Shum, P.W.; Shen, Y.G. [Department of Manufacturing Engineering and Engineering Management (MEEM), City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2005-06-20T23:59:59.000Z

74

An analysis of the x-ray linear dichroism spectrum for NiO thin films grown on vicinal Ag(001)  

SciTech Connect

Antiferromagnetic (AFM) NiO thin films are grown epitaxially on vicinal Ag(118) substrate and investigated by x-ray linear dichroism (XLD). We find that the NiO AFM spin exhibits an in-plane spin reorientation transition from parallel to perpendicular to the step edges with increasing the NiO film thickness. In addition to the conventional L{sub 2} adsorption edge, x-ray linear dichroism (XLD) effect at the Ni L{sub 3} adsorption edge is also measured and analyzed. The result identifies a small energy shift of the L{sub 3} peak. Temperature-dependent measurement confirms that the observed XLD effect in this system at the normal incidence of the x-rays originates entirely from the NiO magnetic ordering.

Wu, Y.Z.; Zhao, Y.; Arenholz, E.; Young, A.T.; Sinkovic, B.; Qiu, Z.Q.

2008-05-10T23:59:59.000Z

75

Lattice location of deuterium in plasma and gas charged Mg doped GaN  

SciTech Connect

The authors have used ion channeling to examine the lattice configuration of deuterium in Mg doped GaN grown by MOCVD. The deuterium is introduced both by exposure to deuterium gas and to ECR plasmas. A density functional approach including lattice relaxation, was used to calculate total energies for various locations and charge states of hydrogen in the wurtzite Mg doped GaN lattice. Computer simulations of channeling yields were used to compare results of channeling measurements with calculated yields for various predicted deuterium lattice configurations.

Wampler, W.R.; Barbour, J.C.; Seager, C.H.; Myers, S.M. Jr.; Wright, A.F.; Han, J.

1999-12-02T23:59:59.000Z

76

Structure of cadmium selen-telluride alloy films grown by the thermal-screen method under highly nonequilibrium conditions  

SciTech Connect

The results of technological experiments and structural investigations of films of CdSe{sub x}Te{sub 1-x} alloys synthesized by the thermal-screen method on heated and cooled substrates (under highly nonequilibrium conditions) are presented. It is shown that the synthesis of the entire range of compositions of alloy films with the structure from epitaxial to amorphous is possible from the mechanical mixture of CdSe and CdTe powders of the same composition under highly nonequilibrium conditions. The electron diffraction patterns and the microphotographs of film surfaces are reported.

Belyaev, A. P., E-mail: Belyaev@lti-gti.ru; Rubets, V. P.; Antipov, V. V.; Toshkhodzhaev, Kh. A. [St. Petersburg State Technological Institute (Technical University) (Russian Federation)

2009-06-15T23:59:59.000Z

77

Structural controlled magnetic anisotropy in Heusler L1{sub 0}-MnGa epitaxial thin films  

Science Conference Proceedings (OSTI)

Ferromagnetic L1{sub 0}-MnGa thin films have been epitaxially grown on GaN, sapphire, and MgO substrates using molecular beam epitaxy. Using diffraction techniques, the epitaxial relationships are determined. It is found that the crystalline orientation of the films differ due to the influence of the substrate. By comparing the magnetic anisotropy to the structural properties, a clear correlation could be established indicating that the in-plane and out-of-plane anisotropy is directly determined by the crystal orientation of the film and could be controlled via selection of the substrates. This result could be helpful in tailoring magnetic anisotropy in thin films for spintronic applications.

Wang Kangkang; Lu Erdong; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Knepper, Jacob W.; Yang Fengyuan [Department of Physics, Ohio State University, 191 Woodruff Ave., Columbus, Ohio 43210 (United States)

2011-04-18T23:59:59.000Z

78

Sb[subscript 2]Te[subscript 3] and Bi[subscript 2]Te[subscript 3] Thin Films Grown by Room-Temperature MBE  

Science Conference Proceedings (OSTI)

Sb{sub 2}Te3 and Bi{sub 2}Te3 thin films were grown on SiO{sub 2} and BaF{sub 2} substrates at room temperature using molecular beam epitaxy. Metallic layers with thicknesses of 0.2 nm were alternately deposited at room temperature, and the films were subsequently annealed at 250 C for 2 h. x-Ray diffraction and energy-filtered transmission electron microscopy (TEM) combined with high-accuracy energy-dispersive x-ray spectrometry revealed stoichiometric films, grain sizes of less than 500 nm, and a texture. High-quality in-plane thermoelectric properties were obtained for Sb{sub 2}Te3 films at room temperature, i.e., low charge carrier density (2.6 x 10{sup 19} cm{sup -3}, large thermopower (130 {micro}V K{sup -1}), large charge carrier mobility (402 cm{sup 2} V{sup -1} s{sup -1}), and resulting large power factor (29 {micro}W cm{sup -1} K{sup -2}). Bi{sub 2}Te3 films also showed low charge carrier density (2.7 x 10{sup 19} cm{sup -3}), moderate thermopower (-153 {micro}V K{sup -1}), but very low charge carrier mobility (80 cm{sup 2} V{sup -1} s{sup -1}), yielding low power factor (8 {micro}W cm{sup -1} K{sup -2}). The low mobilities were attributed to Bi-rich grain boundary phases identified by analytical energy-filtered TEM.

Aabdin, Z.; Peranio, N.; Winkler, M.; Bessas, D.; König, J.; Hermann, R.P.; Böttner, H.; Eibl, O. (Julich); (Tubingen); (Fraunhofer)

2012-10-23T23:59:59.000Z

79

Electron scattering mechanisms in GZO films grown on a-sapphire substrates by plasma-enhanced molecular beam epitaxy  

Science Conference Proceedings (OSTI)

We report on the mechanisms governing electron transport using a comprehensive set of ZnO layers heavily doped with Ga (GZO) grown by plasma-enhanced molecular-beam epitaxy on a-plane sapphire substrates with varying oxygen-to-metal ratios and Ga fluxes. The analyses were conducted by temperature dependent Hall measurements which were supported by microstructural investigations as well. Highly degenerate GZO layers with n > 5 x 10{sup 20} cm{sup -3} grown under metal-rich conditions (reactive oxygen-to-metal ratio mobility in the temperature range from 15 to 330 K and the grain-boundary scattering governed by quantum-mechanical tunnelling is negligible. However, due to the polar nature of ZnO having high crystalline quality, polar optical phonon scattering cannot be neglected for temperatures above 150 K, because it further reduces mobility although its effect is still substantially weaker than the ionized impurity scattering even at room temperature (RT). Analysis of transport measurements and sample microstructures by x-ray diffraction and transmission electron microscopy led to a correlation between the grain sizes in these layers and mobility even for samples with a carrier concentration in the upper 10{sup 20} cm{sup -3} range. In contrast, electron transport in GZO layers grown under oxygen-rich conditions (reactive oxygen-to-metal ratio >1), which have inclined grain boundaries and relatively smaller grain sizes of 10-20 nm by x-ray diffraction, is mainly limited by compensation caused by acceptor-type point-defect complexes, presumably (Ga{sub Zn}-V{sub Zn}), and scattering on grain boundaries. The GZO layers with n mobility but with much higher RT mobility values compared to the samples grown under oxygen-rich conditions [34 vs. 7.5 cm{sup 2}/V{center_dot}s]. Properties of GZO layers grown under different conditions clearly indicate that to achieve highly conductive GZO, metal-rich conditions instead of oxygen-rich conditions have to be used.

Liu, H. Y.; Avrutin, V.; Izyumskaya, N.; Oezguer, Ue.; Morkoc, H. [Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Yankovich, A. B.; Kvit, A. V.; Voyles, P. M. [Department of Materials Science and Engineering, University Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-05-15T23:59:59.000Z

80

Orthodox etching of HVPE-grown GaN  

E-Print Network (OSTI)

orthodox etching in molten salts (KOH [9], eutectic alloy ofnot only to etching in molten salts (KOH, KOH+NaOH eutectic)important for etching in molten salts of morphologically

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Dielectrics for GaN based MIS-diodes  

SciTech Connect

GaN MIS diodes were demonstrated utilizing AlN and Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) as insulators. A 345 {angstrom} of AlN was grown on the MOCVD grown n-GaN in a MOMBE system using trimethylamine alane as Al precursor and nitrogen generated from a wavemat ECR N2 plasma. For the Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) growth, a multi MBE chamber was used and a 195 {angstrom} oxide is E-beam evaporated from a single crystal source of Ga{sub 5}Gd{sub 3}O{sub 12}. The forward breakdown voltage of AlN and Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) diodes are 5V and 6V, respectively, which are significantly improved from {approximately} 1.2 V of schottky contact. From the C-V measurements, both kinds of diodes showed good charge modulation from accumulation to depletion at different frequencies. The insulator GaN interface roughness and the thickness of the insulator were measured with x-ray reflectivity.

Ren, F.; Abernathy, C.R.; MacKenzie, J.D. [Univ. of Florida, Gainesville, FL (United States)] [and others

1998-02-01T23:59:59.000Z

82

GaN High Power Devices  

SciTech Connect

A brief review is given of recent progress in fabrication of high voltage GaN and AlGaN rectifiers, GaN/AlGaN heterojunction bipolar transistors, GaN heterostructure and metal-oxide semiconductor field effect transistors. Improvements in epitaxial layer quality and in fabrication techniques have led to significant advances in device performance.

PEARTON,S.J.; REN,F.; ZHANG,A.P.; DANG,G.; CAO,X.A.; LEE,K.P.; CHO,H.; GILA,B.P.; JOHNSON,J.W.; MONIER,C.; ABERNATHY,C.R.; HAN,JUNG; BACA,ALBERT G.; CHYI,J.-I.; LEE,C.-M.; NEE,T.-E.; CHUO,C.-C.; CHI,G.C.; CHU,S.N.G.

2000-07-17T23:59:59.000Z

83

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

Science Conference Proceedings (OSTI)

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.

Vladimir Dmitriev

2007-06-30T23:59:59.000Z

84

Molecular beam epitaxy-grown wurtzite MgS thin films for solar-blind ultra-violet detection  

SciTech Connect

Molecular beam epitaxy grown MgS on GaAs(111)B substrate was resulted in wurtzite phase, as demonstrated by detailed structural characterizations. Phenomenological arguments were used to account for why wurtzite phase is preferred over zincblende phase or its most stable rocksalt phase. Results of photoresponse and reflectance measurements performed on wurtzite MgS photodiodes suggest a direct bandgap at around 5.1 eV. Their response peaks at 245 nm with quantum efficiency of 9.9% and enjoys rejection of more than three orders at 320 nm and close to five orders at longer wavelengths, proving the photodiodes highly competitive in solar-blind ultraviolet detection.

Lai, Y. H.; He, Q. L. [Nano Science and Nano Technology Program, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China) [Nano Science and Nano Technology Program, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China); Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China); Cheung, W. Y.; Lok, S. K.; Wong, K. S.; Sou, I. K. [Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China)] [Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, HKSAR, People's Republic of China (China); Ho, S. K. [Faculty of Science and Technology, University of Macau, Macau, People's Republic of China (China)] [Faculty of Science and Technology, University of Macau, Macau, People's Republic of China (China); Tam, K. W. [Department of Electrical and Electronics Engineering, University of Macau, Macau, People's Republic of China (China)] [Department of Electrical and Electronics Engineering, University of Macau, Macau, People's Republic of China (China)

2013-04-29T23:59:59.000Z

85

Electron Beam-induced Light Emission and Transport in GaN Nanowires  

SciTech Connect

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.

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

2006-05-10T23:59:59.000Z

86

Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes  

SciTech Connect

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.

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

87

Growth of cubic GaN quantum dots  

SciTech Connect

Zinc-blende GaN quantum dots were grown on 3C-AlN(001) by two different methods in a molecular beam epitaxy system. The quantum dots in method A were fabricated by the Stranski-Krastanov growth process. The quantum dots in method B were fabricated by droplet epitaxy, a vapor-liquid-solid process. The density of the quantum dots was controllable in a range of 10{sup 8} cm{sup -2} to 10{sup 12} cm{sup -2}. Reflection high energy electron diffraction analysis confirmed the zinc-blende crystal structure of the QDs. Photoluminescence spectroscopy revealed the optical activity of the QDs, the emission energy was in agreement with the exciton ground state transition energy of theoretical calculations.

Schupp, T.; Lischka, K.; As, D. J. [Universitaet Paderborn, Department Physik, Warburger Str.100, 33095 Paderborn (Germany); Meisch, T.; Neuschl, B.; Feneberg, M.; Thonke, K. [Institut fuer Quantenmaterie, Universitaet Ulm, 89069 Ulm (Germany)

2010-11-01T23:59:59.000Z

88

The Effect of Hydrogen Carrier Gas on the Morphological Evolution and Material Properties of GaN on Sapphire  

DOE Green Energy (OSTI)

In-situ optical reflectance is used to monitor the morphological evolution of the two-step GaN growth on sapphire. The amount of H{sub 2} carrier gas used in the growth is observed to strongly influence the morphological evolution of the low temperature buffer layer and the subsequent high temperature nucleation behavior, which in turn affects the structural and electrical properties of the GaN epitaxial films. The optical reflectance transients correlate with the sizes and distributions of nuclei as observed by AFM.

Ng, T.B.; Han, J.; Biefeld, R.M.; Zolper, J.C.; Crawford, M.H.; Follstaell, D.M.

1998-01-01T23:59:59.000Z

89

N8, Design Principles for Light-Trapping in Thin Silicon Films with ...  

Science Conference Proceedings (OSTI)

Unfortunately, photon absorption in the near-infrared spectrum is very weak in .... on Polar, Nonpolar, and Semipolar GaN Orientations Grown by Ammonia MBE ..... Photoelectrode for Water Oxidation and in Photoelectrochemical Solar Cells.

90

Study of high quality indium nitride films grown on Si(100) substrate by RF-MOMBE with GZO and AlN buffer layers  

Science Conference Proceedings (OSTI)

Wurtzite structure InN films were prepared on Si(100) substrates using radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE) system. Ga-doped ZnO (GZO) and Amorphous AlN (a-AlN) film were used as buffer layers for InN films growth. Structural, ...

Wei-Chun Chen, Shou-Yi Kuo

2012-01-01T23:59:59.000Z

91

Giant magnetocaloric effect of Mn{sub 0.92}Ba{sub 0.08}As thin film grown on Al{sub 2}O{sub 3}(0001) substrate  

SciTech Connect

The epitaxial Mn{sub 0.92}Ba{sub 0.08}As thin film was grown on Al{sub 2}O{sub 3}(0001) substrate by molecular beam epitaxy. The Curie temperature (T{sub C}) around 350 K was enhanced with the addition of Ba, compared to that of bulk MnAs (T{sub C} {approx} 318 K). We have observed the linear resistivity versus the square of temperature and high negative magnetoresistance near Curie temperature. Moreover, the giant magnetocaloric effect was found with maximum magnetic entropy change, 65 J/kgK, around room temperature at 5 T.

Dang Duc Dung [Department of Physics, University of Ulsan, Ulsan 690-749 (Korea, Republic of); Department of General Physics, School of Engineering, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); Duong Anh Tuan; Duong Van Thiet; Shin, Yooleemi; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 690-749 (Korea, Republic of)

2012-04-01T23:59:59.000Z

92

Anomalous Chemical Expansion Behavior of Pr[subscript 0.2]Ce[subscript 0.8]O[subscript 2-?] Thin Films Grown by Pulsed Laser Deposition  

E-Print Network (OSTI)

The chemomechanical and electrical properties of (Pr,Ce)O[subscript 2-?] thin films were studied between 30 and 875°C in air by in situ X-ray diffraction and complex impedance spectroscopy measurements. Reduction/oxidation ...

Kuru, Y.

93

Photoluminescence properties of SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+} thin phosphor films grown by pulsed laser deposition  

SciTech Connect

Thin films of SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+} phosphor were deposited on silicon [Si (100)] substrates using a 248 nm KrF pulsed laser. Deposition parameters, such as substrate temperature, pulse repetition rate, number of laser pulses, and base pressure, were varied during the film deposition process. Based on the x-ray diffraction data, all the films were amorphous but were emitting visible light when excited by a monochromatic xenon lamp. The chemical composition and the stoichiometry of the films determined by the Rutherford backscattering spectroscopy were consistent with the commercial SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+} powder used to prepare the films. Photoluminescence (PL) emission spectra of the films were characterized by major green emission with a maximum at {approx}520 nm and minor red emission with a maximum at 630 nm. The green and red photoluminescence at 520 and 630 nm are associated with the 4f{sup 6}5d{yields}4f{sup 7}({sup 8}S{sub 7/2}) and {sup 5}D{sub 0}-{sup 7}F{sub 2} transitions of Eu{sup 2+} and residual Eu{sup 3+} ions, respectively. Brighter films were shown to have relatively higher values of the root mean square surface roughness, which were determined from the atomic force microscopy data. The effects of processing parameters on the PL intensity are discussed.

Ntwaeaborwa, O. M.; Nsimama, P. D.; Pitale, Shreyas; Nagpure, I. M.; Kumar, Vinay; Coetsee, E.; Terblans, J. J.; Swart, H. C.; Sechogela, P. T. [Department of Physics, University of the Free State, Bloemfontein ZA 9300 (South Africa); Materials Research Department, Ithemba Labs, Somerset West ZA7130 (South Africa)

2010-07-15T23:59:59.000Z

94

Deposition of stress free c-axis oriented LiNbO{sub 3} thin film grown on (002) ZnO coated Si substrate  

Science Conference Proceedings (OSTI)

C-axis oriented lithium niobate thin films have been deposited on Si substrate using RF sputtering technique. A thin buffer layer of c-axis (002) oriented ZnO on Si substrate has been used as a nucleating layer to promote the growth of (006) oriented LiNbO{sub 3} film. The processing gas composition and pressure are found to be very critical in obtaining stress free LiNbO{sub 3} film having desired (006) orientation. The LiNbO{sub 3} films deposited under unique combination of sputtering pressure (10 mTorr) and argon percentage (80%) in reactive gas (Ar + O{sub 2}) composition become almost stress free having lattice parameter (1.3867 A) close to the bulk value. The observed variation in the structural properties and optical phonon modes observed by Raman spectroscopic studies of the oriented LiNbO{sub 3} thin film with stress has been correlated with growth kinetics.

Shandilya, Swati; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Tomar, Monika [Miranda House, University of Delhi, Delhi 110007 (India)

2012-05-15T23:59:59.000Z

95

Tuning of the surface plasmon resonance in TiO{sub 2}/Au thin films grown by magnetron sputtering: The effect of thermal annealing  

Science Conference Proceedings (OSTI)

Nanocomposites consisting of a dielectric matrix, such as TiO{sub 2}, with embedded noble metal nanoparticles (NPs) possess specific optical properties due to the surface plasmon resonance (SPR) effect, interesting for several applications. The aim of this work is to demonstrate that these properties are sensitive to the nanostructure of magnetron-sputtered TiO{sub 2}/Au thin films, which can be tuned by annealing. We study the role of the shape and size distribution of the NPs, as well as the influence of the crystallinity and phase composition of the host matrix on the optical response of the films. All these characteristics can be modified by vacuum annealing treatments of the deposited films. A theoretical interpretation and modeling of the experimental results obtained is presented. The model involves a modified Maxwell-Garnett approach for the effective dielectric function of the composite (describing the SPR effect) and the transfer matrix formalism for multilayer optics. Input data are based on the experimental information obtained from the detailed structural characterization of the films. It is shown that the annealing treatments can be used for controlling the optical properties of the composite films, making them attractive for decorative coatings.

Torrell, M.; Kabir, R.; Cunha, L.; Vasilevskiy, M. I.; Vaz, F. [Centro de Fisica, Universidade do Minho, 4710-057 Braga (Portugal); Cavaleiro, A. [Departamento de Engenharia Mecanica, SEC-CEMUC, Universidade de Coimbra, Polo II, 3030-788 Coimbra (Portugal); Alves, E.; Barradas, N. P. [Instituto Tecnologico e Nuclear, Departamento de Fisica, 2686-953 Sacavem (Portugal)

2011-04-01T23:59:59.000Z

96

Two-dimensional weak anti-localization in Bi{sub 2}Te{sub 3} thin film grown on Si(111)-(7 Multiplication-Sign 7) surface by molecular beam epitaxy  

SciTech Connect

We report on low temperature transport studies of Bi{sub 2}Te{sub 3} topological insulator thin films grown on Si(111)-(7 Multiplication-Sign 7) surface by molecular beam epitaxy. A sharp increase in the magnetoresistance with magnetic field at low temperature indicates the existence of weak anti-localization. The measured weak anti-localization effect agrees well with the Hikami-Larkin-Nagaoka model, and the extracted phase coherence length shows a power-law dependence with temperature indicating the existence of a two-dimensional system. An insulating ground state has also been observed at low temperature showing a logarithmic divergence of the resistance that appears to be the influence of electron-electron interaction in a two-dimensional system.

Roy, Anupam; Guchhait, Samaresh; Sonde, Sushant; Dey, Rik; Pramanik, Tanmoy; Rai, Amritesh; Movva, Hema C. P.; Banerjee, Sanjay K. [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States)] [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States); Colombo, Luigi [Texas Instruments, 12500 TI Boulevard, Dallas, Texas 75266 (United States)] [Texas Instruments, 12500 TI Boulevard, Dallas, Texas 75266 (United States)

2013-04-22T23:59:59.000Z

97

Effects of laser energy fluence on the onset and growth of the Rayleigh-Taylor instabilities and its influence on the topography of the Fe thin film grown in pulsed laser deposition facility  

SciTech Connect

The effect of laser energy fluence on the onset and growth of Rayleigh-Taylor (RT) instabilities in laser induced Fe plasma is investigated using time-resolved fast gated imaging. The snow plow and shock wave models are fitted to the experimental results and used to estimate the ablation parameters and the density of gas atoms that interact with the ablated species. It is observed that RT instability develops during the interface deceleration stage and grows for a considerable time for higher laser energy fluence. The effects of RT instabilities formation on the surface topography of the Fe thin films grown in pulsed laser deposition system are investigated (i) using different laser energy fluences for the same wavelength of laser radiation and (ii) using different laser wavelengths keeping the energy fluence fixed. It is concluded that the deposition achieved under turbulent condition leads to less smooth deposition surfaces with bigger sized particle agglomerates or network.

Mahmood, S. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Department of Physics, University of Karachi, Karachi 75270 (Pakistan); Rawat, R. S.; Wang, Y.; Lee, S.; Tan, T. L.; Springham, S. V.; Lee, P. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Zakaullah, M. [Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)

2012-10-15T23:59:59.000Z

98

Impact of defects on the electrical transport, optical properties and failure mechanisms of GaN nanowires.  

SciTech Connect

We present the results of a three year LDRD project that focused on understanding the impact of defects on the electrical, optical and thermal properties of GaN-based nanowires (NWs). We describe the development and application of a host of experimental techniques to quantify and understand the physics of defects and thermal transport in GaN NWs. We also present the development of analytical models and computational studies of thermal conductivity in GaN NWs. Finally, we present an atomistic model for GaN NW electrical breakdown supported with experimental evidence. GaN-based nanowires are attractive for applications requiring compact, high-current density devices such as ultraviolet laser arrays. Understanding GaN nanowire failure at high-current density is crucial to developing nanowire (NW) devices. Nanowire device failure is likely more complex than thin film due to the prominence of surface effects and enhanced interaction among point defects. Understanding the impact of surfaces and point defects on nanowire thermal and electrical transport is the first step toward rational control and mitigation of device failure mechanisms. However, investigating defects in GaN NWs is extremely challenging because conventional defect spectroscopy techniques are unsuitable for wide-bandgap nanostructures. To understand NW breakdown, the influence of pre-existing and emergent defects during high current stress on NW properties will be investigated. Acute sensitivity of NW thermal conductivity to point-defect density is expected due to the lack of threading dislocation (TD) gettering sites, and enhanced phonon-surface scattering further inhibits thermal transport. Excess defect creation during Joule heating could further degrade thermal conductivity, producing a viscous cycle culminating in catastrophic breakdown. To investigate these issues, a unique combination of electron microscopy, scanning luminescence and photoconductivity implemented at the nanoscale will be used in concert with sophisticated molecular-dynamics calculations of surface and defect-mediated NW thermal transport. This proposal seeks to elucidate long standing material science questions for GaN while addressing issues critical to realizing reliable GaN NW devices.

Armstrong, Andrew M.; Aubry, Sylvie; Shaner, Eric Arthur; Siegal, Michael P.; Li, Qiming; Jones, Reese E.; Westover, Tyler; Wang, George T.; Zhou, Xiao Wang; Talin, Albert Alec; Bogart, Katherine Huderle Andersen; Harris, C. Thomas; Huang, Jian Yu

2010-09-01T23:59:59.000Z

99

Fabrication and characterization of GaN junction field effect transistors  

SciTech Connect

Junction field effect transistors (JFET) were fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition. The DC and microwave characteristics, as well as the high temperature performance of the devices were studied. These devices exhibited excellent pinch-off and a breakdown voltage that agreed with theoretical predictions. An extrinsic transconductance (g{sub m}) of 48 mS/mm was obtained with a maximum drain current (I{sub D}) of 270 mA/mm. The microwave measurement showed an f{sub T} of 6 GHz and an f{sub max} of 12 GHz. Both the I{sub D} and the g{sub m} were found to decrease with increasing temperature, possibly due to lower electron mobility at elevated temperatures. These JFETs exhibited a significant current reduction after a high drain bias was applied, which was attributed to a partially depleted channel caused by trapped electrons in the semi-insulating GaN buffer layer.

Zhang, L.; Lester, L.F.; Baca, A.G.; Shul, R.J.; Chang, P.C.; Willison, C.L.; Mishra, U.K.; Denbaars, S.P.; Zolper, J.C.

2000-01-11T23:59:59.000Z

100

Cathodoluminescence Microanalysis of Suspended GaN Nano ...  

Science Conference Proceedings (OSTI)

CL from bulk GaN is dominated by the ~3.4 eV near-band-edge emission. In contrast, the suspended nano-membranes emit a broad defect associated emission ...

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Monolithic single GaN nanowire laser with photonic crystal microcavity on silicon  

SciTech Connect

Optically pumped lasing at room temperature in a silicon based monolithic single GaN nanowire with a two-dimensional photonic crystal microcavity is demonstrated. Catalyst-free nanowires with low density ({approx}10{sup 8} cm{sup -2}) are grown on Si by plasma-assisted molecular beam epitaxy. High resolution transmission electron microscopy images reveal that the nanowires are of wurtzite structure and they have no observable defects. A single nanowire laser fabricated on Si is characterized by a lasing transition at {lambda}=371.3 nm with a linewidth of 0.55 nm. The threshold is observed at a pump power density of {approx}120 kW/cm{sup 2} and the spontaneous emission factor {beta} is estimated to be 0.08.

Heo, Junseok; Guo Wei; Bhattacharya, Pallab [Center for Nanoscale Photonics and Spintronics, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2011-01-10T23:59:59.000Z

102

Magnetically active vacancy related defects in irradiated GaN layers  

Science Conference Proceedings (OSTI)

We present the studies of magnetic properties of 2 MeV {sup 4}He{sup +}-irraadiated GaN grown by metal-organic chemical-vapor deposition. Particle irradiation allowed controllable introduction of Ga-vacancy in the samples. The magnetic moments with concentrations changing between 4.3 and 8.3 Multiplication-Sign 10{sup 17}cm{sup -3} showing superparamagnetic blocking at room temperature are observed. The appearance of clear hysteresis curve at T=5K with coercive field of about H{sub C} Almost-Equal-To 270 Oe suggests that the formation of more complex Ga vacancy related defects is promoted with increasing Ga vacancy content. The small concentration of the observed magnetically active defects with respect to the total Ga-vacancy concentration suggests that the presence of the oxygen/hydrogen-related vacancy complexes is the source of the observed magnetic moments.

Kilanski, L.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto Espoo (Finland); Szymczak, R. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Kruszka, R. [Institute of Electron Technology, Al. Lotnikow 46, 02-668 Warsaw (Poland)

2012-08-13T23:59:59.000Z

103

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

Science Conference Proceedings (OSTI)

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.

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

104

Atom probe tomography characterisation of a laser diode structure grown by molecular beam epitaxy  

E-Print Network (OSTI)

by the two techniques. 7 2. Experiment The LD structure wafer was grown using a Veeco V80 MBE system, on a commercially available ultra-low TD density template consisting of ~10 µm of GaN grown by MOVPE on a sapphire substrate (Lumilog ULD template... of Europe to growth of the sample. SEB also thanks the Institute of Physics for the award of the annual Roy prize for a doctoral thesis on condensed matter and material physics, and the 20 Centre for Advanced Structural Ceramics for the award...

Bennett, Samantha; Smeeton, Tim; Saxey, David; Smith, George; Hooper, Stewart; Heffernan, Jonathan; Humphreys, Colin; Oliver, Rachel

2012-03-06T23:59:59.000Z

105

High Voltage GaN Schottky Rectifiers  

SciTech Connect

Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and {ge}15 for the 2kV diodes. Reverse recovery times were <0.2{micro}sec for devices switched from a forward current density of {approx}500A{center_dot}cm{sup -2} to a reverse bias of 100V.

CAO,X.A.; CHO,H.; CHU,S.N.G.; CHUO,C.-C.; CHYI,J.-I.; DANG,G.T.; HAN,JUNG; LEE,C.-M.; PEARTON,S.J.; REN,F.; WILSON,R.G.; ZHANG,A.P.

1999-10-25T23:59:59.000Z

106

Polarity inversion of N-face GaN using an aluminum oxide interlayer  

Science Conference Proceedings (OSTI)

The polarity of GaN grown by plasma-assisted molecular beam epitaxy was inverted from N-face to Ga-face by inserting a composite AlN/aluminum oxide (AlO{sub x}) interlayer structure at the inversion interface. The change in polarity was verified in situ by reflection high energy electron diffraction via intensity transients and postgrowth surface reconstructions, and ex situ by convergent beam electron diffraction and etch studies in an aqueous potassium hydroxide solution. The inverted materials showed smooth surfaces and good electrical properties. AlGaN/GaN high electron mobility transistors fabricated on the inverted epilayers showed good dc and high frequency performance. A current-gain cutoff frequency (f{sub T}) of 21 GHz and maximum oscillation frequency (f{sub max}) of 61 GHz were measured in devices with a gate length of 0.7 {mu}m. These data compare favorably to those of Ga-face AlGaN/GaN devices with a similar structure grown on Si-face SiC substrates.

Wong, Man Hoi; Mishra, Umesh K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560 (United States); Wu, Feng; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

2010-12-15T23:59:59.000Z

107

Reliability of GaN HEMTs: Electrical and Radiation-induced Failure ...  

Science Conference Proceedings (OSTI)

Symposium, Advanced Materials for Power Electronics, Power Conditioning, and Power Conversion II. Presentation Title, Reliability of GaN HEMTs: Electrical ...

108

Structural Properties of Eu-Doped GaN Investigated by Raman Spectroscopy  

DOE Green Energy (OSTI)

Rare-earth (RE) impurities doped GaN are highly promising candidates for light emitting device applications due to their efficient electroluminescence properties at room temperature. Among those, Eu doped GaN has been identified as an excellent material for the red spectral region due to its strong emission at 620 nm. As a transition internal to the Eu doping atom (4f-4f), light emission originates in a much smaller complex than the more flexibly controllable quantum structures of wells, wires, and dots. This is thought to make the center less susceptible to structural defects and in particular radiation damage in the lattice host. Nevertheless, the lattice host is crucial for providing the excitation in from of free electrons and holes. In this respect, the actual lattice site Eu occupies in the host lattice, i.e. in GaN, is important. A large fraction of Eu atoms are typically inactive which must be attributed to their lattice site and local environment. GaN films implanted with Eu to concentrations of {approx}10{sup 18} cm{sup -3} were subjected to a highly directed beam of 500 keV He{sup +} at a dose of 5 x 10{sup 14} cm{sup -2}. By means of a shadow mask, irradiated and unexposed regions lie very close to each other on the same sample. We used optical and structural analysis to identify the exerted radiation damage. At the full radiation dose, photoluminescence intensity has decayed to {approx}0.01 of its initial value. From the dose dependence of the radiation decay we previously concluded, that this decay is in part due to the destruction of radiative Eu sites [J.W. Tringe, unpublished (2006)]. Along the transition from virgin to irradiated material we analyze the accumulated damage in terms of surface morphology (atomic force microscopy), crystallinity (x-ray diffraction), and phonon dispersion using micro-Raman spectroscopy. In addition to the well-studied E{sub 2}(high) mode, two new vibrational modes at 659 cm{sup -1} and 201 cm{sup -1} were observed in the Eu implanted and annealed sample, prior to He{sup +} irradiation. These modes are either remnants of the implantation damage or related to the Eu impurity. As such they can be indicative of the actual lattice site the Eu atom resides on. After irradiation, broad Raman modes at 300 cm-1 are being observed. This band indicates disorder activated Raman scattering (DARS) due to the radiation damage. An additional narrow mode appears at 672 cm{sup -1}, which can possibly be due to a nitrogen vacancy related vibrational mode. The continuous transition from irradiated to un-irradiated sample allows the direct evolution of radiation damage and its coordinated effects in structural, optical and vibrational properties. By its systematic correlation we anticipate to be able to elucidate the Eu lattice interaction and the processes of radiation damage.

Senawiratne, J; Xia, Y; Detchprohm, T; Tringe, J W; Stevens, C G; Wetzel, C

2006-06-20T23:59:59.000Z

109

Dynamic Model of Hydrogen in GaN  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic Model of Hydrogen in GaN by S. M. Myers and A. F. Wright Motivation-Hydrogen is incorporated into p-type GaN during MOCVD growth, producing highly stable passivation of the Mg acceptors. Complete acceptor activation by thermal H release requires temperatures that threaten material integrity, prompting compromises in device processing. At lower temperatures, forward bias of p-n junctions or electron-beam irradiation produces a metastable, reversible activation without H release. To understand and control such effects, we are developing a mathematical model of H behavior wherein state energies from density-functional theory are employed in diffusion-reaction equations. Previously, we used the greatly simplifying assumptions of local equilibrium among states

110

UV-Photoassisted Etching of GaN in KOH  

SciTech Connect

The etch rate of GaN under W-assisted photoelectrochemical conditions in KOH solutions is found to be a strong function of illumination intensity, solution molarity, sample bias and material doping level. At low e-h pair generation rates, grain boundaries are selectively etched, while at higher illumination intensities etch rates for unintentionally doped (n - 3x 10^12Gcm-3) GaN are 2 1000 .min-l. The etching is diffusion limited under our conditions with an activation energy of - 0.8kCal.mol-1. The etched surfaces are rough, but retain their stoichiometry. PEC etching is found to selectively reveal grain boundaries in GaN under low light illumination conditions. At high lamp powers the rates increase with sample temperature and the application of bias to the PEC cell, while they go through a maximum with KOH solution molarity. The etching is diffusion-limited, producing rough surface morphologies that are suitable in a limited number of device fabrication steps. The surfaces however appear to remain relatively close to their stoichiometric composition.

Abernathy, C.R.; Auh, K.H.; Cho, H.; Donovan, S.M.; Han, J.; Lambers, E.S.; Pearton, S.J.; Ren F.; Shul, R.J.

1998-11-12T23:59:59.000Z

111

Lighting Enhancement of GaN LEDs by Applying p-Type Ni(P):SnO2 ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Multifunctional Oxides. Presentation Title, Lighting Enhancement of GaN LEDs ...

112

Quantized states in homogenous polarized GaInN GaN quantum wells  

E-Print Network (OSTI)

Quantized states in homogenous polarized GaInN GaN quantum wells C. Wetzel1, S. Kamiyama1, H. Amano wells is calculated in a single particle model. The act- ing electric eld in the wells and the band gap-dimensional well layers our approach is based on induction from results obtained at the binary GaN barri- ers

Wetzel, Christian M.

113

GaN membrane-supported UV photodetectors manufactured using nanolithographic processes  

Science Conference Proceedings (OSTI)

Membrane GaN metal-semiconductor-metal (MSM) photodetector structures using nanolithographic techniques have been manufactured for the first time. Very low dark currents and unexpected high values for the responsivity have been obtained. It seems that ... Keywords: GaN, Membrane, Nanolithography, Responsivity, SEM

A. Müller; G. Konstantinidis; M. Dragoman; D. Neculoiu; A. Dinescu; M. Androulidaki; M. Kayambaki; A. Stavrinidis; D. Vasilache; C. Buiculescu; I. Petrini; A. Kostopoulos; D. Dascalu

2009-02-01T23:59:59.000Z

114

Analyzing the growth of In{sub x}Ga{sub 1-x}N/GaN superlattices in self-induced GaN nanowires by x-ray diffraction  

Science Conference Proceedings (OSTI)

Self-induced GaN nanowires are grown by plasma-assisted molecular beam epitaxy, with In{sub x}Ga{sub 1-x}N quantum wells inserted to form an axial superlattice. From the {omega}-2{theta} scans of a laboratory x-ray diffraction experiment, we obtain the superlattice period, the thickness of the quantum wells, and the In content in this layer. The axial growth rate of the In{sub x}Ga{sub 1-x}N quantum wells is significantly enhanced, which we attribute to increased Ga diffusion along the nanowire sidewalls in the presence of In.

Woelz, M.; Kaganer, V. M.; Brandt, O.; Geelhaar, L.; Riechert, H.

2011-06-27T23:59:59.000Z

115

Comparative study of GaN growth process by MOVPE  

SciTech Connect

A comparative study of two different MOVPE reactors used for GaN growth is presented. Computational fluid dynamics (CFD) was used to determine common gas phase and fluid flow behaviors within these reactors. This paper focuses on the common thermal fluid features of these two MOVPE reactors with different geometries and operating pressures that can grow device-quality GaN-based materials. The study clearly shows that several growth conditions must be achieved in order to grow high quality GaN materials. The high-temperature gas flow zone must be limited to a very thin flow sheet above the susceptor, while the bulk gas phase temperature must be very low to prevent extensive pre-deposition reactions. These conditions lead to higher growth rates and improved material quality. A certain range of gas flow velocity inside the high-temperature gas flow zone is also required in order to minimize the residence time and improve the growth uniformity. These conditions can be achieved by the use of either a novel reactor structure such as a two-flow approach or by specific flow conditions. The quantitative ranges of flow velocities, gas phase temperature, and residence time required in these reactors to achieve high quality material and uniform growth are given.

Sun, J.; Redwing, J.M.; Kuech, T.F.

1999-07-01T23:59:59.000Z

116

Epitaxial growth of Dy2O3 thin films on epitaxial Dy-germanide films on Ge(001) substrates  

Science Conference Proceedings (OSTI)

Ultra-thin films of Dy are grown on Ge(001) substrates by molecular beam deposition near room temperature and immediately annealed for solid phase epitaxy at higher temperatures, leading to the formation of DyGe"x films. Thin films of Dy"2O"3 are grown ... Keywords: Dy2O3 film, Ge(001) substrate, High-? oxide, Molecular beam epitaxy (MBE), Structural characterization, Transmission electron microscopy (TEM)

Md. Nurul Kabir Bhuiyan; Mariela Menghini; Jin Won Seo; Jean-Pierre Locquet

2011-04-01T23:59:59.000Z

117

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

E-Print Network (OSTI)

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 ...

Zhou, Xiang

118

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

E-Print Network (OSTI)

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. ...

Chung, Jinwook W. (Jinwook Will)

2011-01-01T23:59:59.000Z

119

RF Power Degradation of GaN High Electron Mobility Transistors  

E-Print Network (OSTI)

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 ...

Joh, Jungwoo

120

Light extraction in individual GaN nanowires on Si for LEDs  

E-Print Network (OSTI)

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 ...

Zhou, Xiang

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

X-ray magnetic circular dichroism of ferromagnetic Co{sub 4}N epitaxial films on SrTiO{sub 3}(001) substrates grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

5-nm thick Co{sub 4}N layers capped with 3-nm thick Au layers were grown epitaxially on SrTiO{sub 3}(001) substrates by molecular beam epitaxy using solid Co and a radio-frequency NH{sub 3} plasma. Spin and orbital magnetic moments of the Co{sub 4}N layers were estimated using x-ray magnetic circular dichroism (XMCD) measurements at 300 K. The site-averaged Co 3d spin magnetic moment is evaluated to be about 1.4 {mu}{sub B}, which is smaller than that predicted theoretically (1.58 {mu}{sub B}). The element-specific XMCD intensities for the Co L{sub 3} edge and N K edge show that the magnetic moment is induced at the N atoms.

Ito, Keita; Harada, Kazunori; Toko, Kaoru; Suemasu, Takashi [Institute of Applied Physics, University of Tsukuba, Ibaraki 305-8573 (Japan); Ye, Mao; Kimura, Akio [Graduate School of Science, Hiroshima University, Hiroshima 739-8526 (Japan); Takeda, Yukiharu; Saitoh, Yuji [Japan Atomic Energy Agency (JAEA), SPring-8, Hyogo 679-5198 (Japan); Akinaga, Hiro [National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki 305-8569 (Japan)

2011-12-19T23:59:59.000Z

122

Geomagnetic observatory GAN Jakub Velimsky K. Chandra Shakar Rao Lars W. Pedersen Ahmed Muslim  

E-Print Network (OSTI)

Geomagnetic observatory GAN Jakub Vel´imsk´y K. Chandra Shakar Rao Lars W. Pedersen Ahmed Muslim´imsk´y et al. (ETH,UK,DTU,NGRI,GMO) Geomagnetic observatory GAN 27.4.2011/KG MFF UK 1 / 16 #12;Participating, Univ. Stuttgart) John Riddick (BGS, retired) Vel´imsk´y et al. (ETH,UK,DTU,NGRI,GMO) Geomagnetic

Cerveny, Vlastislav

123

GaN Metal Oxide Semiconductor Field Effect Transistors  

SciTech Connect

A GaN based depletion mode metal oxide semiconductor field effect transistor (MOSFET) was demonstrated using Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) as the gate dielectric. The MOS gate reverse breakdown voltage was > 35V which was significantly improved from 17V of Pt Schottky gate on the same material. A maximum extrinsic transconductance of 15 mS/mm was obtained at V{sub ds} = 30 V and device performance was limited by the contact resistance. A unity current gain cut-off frequency, f{sub {tau}}, and maximum frequency of oscillation, f{sub max} of 3.1 and 10.3 GHz, respectively, were measured at V{sub ds} = 25 V and V{sub gs} = {minus}20 V.

Ren, F.; Pearton, S.J.; Abernathy, C.R.; Baca, A.; Cheng, P.; Shul, R.J.; Chu, S.N.G.; Hong, M.; Lothian, J.R.; Schurman, M.J.

1999-03-02T23:59:59.000Z

124

GaN directional couplers for integrated quantum photonics  

SciTech Connect

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 [C. K. Hong, et al., Phys. Rev. Lett. 59, 2044 (1987)] with 96% visibility.

Zhang Yanfeng; McKnight, Loyd; Watson, Ian M.; Gu, Erdan; Calvez, Stephane; Dawson, Martin D. [Institute of Photonics, SUPA, University of Strathclyde, Glasgow G4 0NW (United Kingdom); Engin, Erman; Cryan, Martin J.; Thompson, Mark G.; O'Brien, Jeremy L. [Centre for Quantum Photonics, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol BS8 1UB (United Kingdom)

2011-10-17T23:59:59.000Z

125

P2.13 Characterization of a-Plane GaN Layers Grown on Patterned r ...  

Science Conference Proceedings (OSTI)

... attracted significant attention for optoelectronic device applications covering .... Growth of Ingaas on Si(111) with Reduced Size of Selective Growth Window.

126

Fe-doped InN layers grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Iron(Fe)-doped InN (InN:Fe) layers have been grown by molecular beam epitaxy. It is found that Fe-doping leads to drastic increase of residual electron concentration, which is different from the semi-insulating property of Fe-doped GaN. However, this heavy n-type doping cannot be fully explained by doped Fe-concentration ([Fe]). Further analysis shows that more unintentionally doped impurities such as hydrogen and oxygen are incorporated with increasing [Fe] and the surface is degraded with high density pits, which probably are the main reasons for electron generation and mobility reduction. Photoluminescence of InN is gradually quenched by Fe-doping. This work shows that Fe-doping is one of good choices to control electron density in InN.

Wang Xinqiang; Liu Shitao; Ma Dingyu; Zheng Xiantong; Chen Guang; Xu Fujun; Tang Ning; Shen Bo [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Zhang Peng; Cao Xingzhong; Wang Baoyi [State Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Huang Sen; Chen, Kevin J. [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology (Hong Kong); Zhou Shengqiang [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01314 Dresden (Germany); Yoshikawa, Akihiko [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

2012-10-22T23:59:59.000Z

127

Characterization of LiNi?.?Mn?.?O? Thin Film Cathode Prepared by Pulsed Laser Deposition  

E-Print Network (OSTI)

LiNi?.?Mn?.?O? thin films have been grown by pulsed laser deposition (PLD) on stainless steel (SS) substrates. The crystallinity and structure of thin films were investigated by X-ray diffraction (XRD). Microstructure and ...

Xia, Hui

128

Charge Separation of Wurtzite/Zinc-blende Heterojunction GaN Nanowires  

DOE Green Energy (OSTI)

The electronic properties of wurtzite/zinc-blende (WZ/ZB) heterostructure GaN are investigated using first-principles methods. A small component of ZB stacking formed along the growth direction in the WZ GaN nanowires does not show a significant effect on the electronic property, whereas a charge separation of electrons and holes occurs along the directions perpendicular to the growth direction in the ZB stacking. The later case provides an efficient way to separate the charge through controlling crystal structure. These results should have significant implications for most state of the art excitonic solar cells and the tuning region in tunable laser diodes.

Wang, Zhiguo; Li, Jingbo; Gao, Fei; Weber, William J.

2010-08-27T23:59:59.000Z

129

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

E-Print Network (OSTI)

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 ...

Demirtas, Sefa

130

GaN CVD Reactions: Hydrogen and Ammonia Decomposition and the Desorption of Gallium  

DOE Green Energy (OSTI)

Isotopic labeling experiments have revealed correlations between hydrogen reactions, Ga desorption, and ammonia decomposition in GaN CVD. Low energy electron diffraction (LEED) and temperature programmed desorption (TPD) were used to demonstrate that hydrogen atoms are available on the surface for reaction after exposing GaN(0001) to deuterium at elevated temperatures. Hydrogen reactions also lowered the temperature for Ga desorption significantly. Ammonia did not decompose on the surface before hydrogen exposure. However, after hydrogen reactions altered the surface, N15H3 did undergo both reversible and irreversible decomposition. This also resulted in the desorption of N2 of mixed isotopes below the onset of GaN sublimation, This suggests that the driving force of the high nitrogen-nitrogen bond strength (226 kcal/mol) can lead to the removal of nitrogen from the substrate when the surface is nitrogen rich. Overall, these findings indicate that hydrogen can influence G-aN CVD significantly, being a common factor in the reactivity of the surface, the desorption of Ga, and the decomposition of ammonia.

Bartram, Michael E.; Creighton, J. Randall

1999-05-26T23:59:59.000Z

131

Photonic-crystal GaN light-emitting diodes with tailored guided modes distribution  

E-Print Network (OSTI)

Photonic-crystal GaN light-emitting diodes with tailored guided modes distribution Aurélien David of photonic crystal PhC -assisted gallium nitride light-emitting diodes LEDs to the existence of unextracted a promising but challenging solution towards efficient solid-state lighting. Conventional GaN-based light-emitting

Recanati, Catherine

132

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

E-Print Network (OSTI)

GaN light-emitting diodes with Archimedean lattice photonic crystals Aurélien David,a Tetsuo Fujii 2005; published online 16 February 2006 We study GaN-based light emitting diodes incorporating light- emitting diodes LEDs , as they could extract the emitted light otherwise trapped inside

Recanati, Catherine

133

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

E-Print Network (OSTI)

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 ...

Demirtas, Sefa

134

Pulsed laser deposition of ITO thin films and their characteristics  

SciTech Connect

The indium tin oxide (ITO) thin films are grown on quartz glass substrates by the pulsed laser deposition method. The structural, electrical, and optical properties of ITO films are studied as a function of the substrate temperature, the oxygen pressure in the vacuum chamber, and the Sn concentration in the target. The transmittance of grown ITO films in the visible spectral region exceeds 85%. The minimum value of resistivity 1.79 Multiplication-Sign 10{sup -4} {Omega} cm has been achieved in the ITO films with content of Sn 5 at %.

Zuev, D. A., E-mail: zuewda@yandex.ru; Lotin, A. A.; Novodvorsky, O. A.; Lebedev, F. V.; Khramova, O. D. [Russian Academy of Sciences, Institute on Laser and Information Technologies (Russian Federation); Petuhov, I. A.; Putilin, Ph. N.; Shatohin, A. N.; Rumyanzeva, M. N.; Gaskov, A. M. [Moscow State University, Faculty of Chemistry (Russian Federation)

2012-03-15T23:59:59.000Z

135

In-situ post-deposition thermal annealing of co-evaporated Cu(InGa)Se2 thin films deposited at low temperatures  

DOE Green Energy (OSTI)

equivalent to devices made from films grown at 550°C. Films originally deposited at 300°C yielded devices after post-deposition annealing with VOC close to that of devices made from films grown at 550°C, despite smaller grain size.

Wilson, James D.; McCandless, Brian E.; Birkmire, Robert W.; Shafarman, William N.

2009-06-09T23:59:59.000Z

136

A model for the critical voltage for electrical degradation of GaN high electron mobility transistors  

E-Print Network (OSTI)

We have found that there is a critical drain-to-gate voltage beyond which GaN high-electron mobility transistors start to degrade in electrical-stress experiments. The critical voltage depends on the detailed voltage biasing ...

Joh, Jungwoo

137

Electron Scattering Mechanism of FTO Films Grown by Spray ...  

Science Conference Proceedings (OSTI)

Accelerated Light Induced Degradation, ALID, for Monitoring of Defects in PV Silicon ... Silicon Solar Cells Evaluated by LBIC and Equivalent Circuit Model.

138

Microstructural Evolution of SnS Thin Films Grown by ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, 2012 TMS Annual Meeting & Exhibition. Symposium , Energy Nanomaterials. Presentation Title, Microstructural Evolution of SnS ...

139

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

E-Print Network (OSTI)

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

Nabben, Reinhard

140

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

SciTech Connect

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.

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

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Superlattice-like stacking fault array in ion-irradiated GaN  

SciTech Connect

Controlling defects in crystalline solids is of technological importance for realizing desirable materials properties. Irradiation with energetic particles is useful for designing the spatial distribution and concentration of defects in materials. Here, we performed ion irradiation into hexagonal GaN with the wurtzite structure and demonstrated the spontaneous formation of superlattice-like stacking fault arrays. It was found that the modulation period can be controlled by irradiation conditions and post-irradiation heat treatments.

Ishimaru, Dr. Manabu [Osaka University; Usov, Igor Olegovich [ORNL; Zhang, Yanwen [ORNL; Weber, William J [ORNL

2012-01-01T23:59:59.000Z

142

Ohmic contacts to Si-implanted and un-implanted n-type GaN  

SciTech Connect

We report on ohmic contacts to Si-implanted and un-implanted n-type GaN on sapphire. A ring shaped contact design avoids the need to isolate the contact structures by additional implantation or etching. Metal layers of Al and Ti/Al were investigated. On un-implanted GaN, post metalization annealing was performed in an RTA for 30 seconds in N{sub 2} at 700, 800, and 900 C. A minimum specific contact resistance (r{sub c}) of 1.4{times}10{sup -5} {Omega}{minus}cm{sup 2} was measured for Ti/Al at an annealing temperature of 800 C. Although these values are reasonably low, variations of 95% in specific contact resistance were measured within a 500 {mu}m distance on the wafer. These results are most likely caused by the presence of compensating hydrogen. Specific contact resistance variation was reduced from 95 to 10% by annealing at 900 C prior to metalization. On Si-implanted GaN, un-annealed ohmic contacts were formed with Ti/Al metalization. The implant activation anneal of 1120 C generates nitrogen vacancies that leave the surface heavily n-type, which makes un-annealed ohmic contacts with low contact resistivity possible.

Brown, J; Ramer, J.; Zheng, L.F.; Hersee, S.D. [New Mexico Univ., Albuquerque, NM (United States). Center for High Technology Materials; Zolper, J. [Sandia National Labs., Albuquerque, NM (United States)

1996-02-01T23:59:59.000Z

143

Formation of manganese {delta}-doped atomic layer in wurtzite GaN  

Science Conference Proceedings (OSTI)

We describe the formation of a {delta}-doped manganese layer embedded within c-plane wurtzite gallium nitride using a special molecular beam epitaxy growth process. Manganese is first deposited on the gallium-poor GaN (0001) surface, forming a {radical}(3) Multiplication-Sign {radical}(3)-R30 Degree-Sign reconstructed phase. This well-defined surface reconstruction is then nitrided using plasma nitridation, and gallium nitride is overgrown. The manganese content of the {radical}(3) Multiplication-Sign {radical}(3)-R30 Degree-Sign phase, namely one Mn per each {radical}(3) Multiplication-Sign {radical}(3)-R30 Degree-Sign unit cell, implies that the MnGaN alloy layer has a Mn concentration of up to 33%. The structure and chemical content of the surface are monitored beginning from the initial growth stage up through the overgrowth of 20 additional monolayers (MLs) of GaN. An exponential-like drop-off of the Mn signal with increasing GaN monolayers, as measured by Auger electron spectroscopy, indicates that the highly concentrated Mn layer remains at the {delta}-doped interface. A model of the resultant {delta}-doped structure is formulated based on the experimental data, and implications for possible spintronic applications are discussed.

Shi Meng; Chinchore, Abhijit; Wang Kangkang; Mandru, Andrada-Oana; Liu Yinghao; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States)

2012-09-01T23:59:59.000Z

144

Studies on the properties of sputter-deposited Ag-doped ZnO films  

Science Conference Proceedings (OSTI)

Ag-doped ZnO films were prepared by simultaneous rf magnetron sputtering of ZnO and dc magnetron sputtering of Ag on glass substrate. The influences of dopant content and substrate temperature on the properties of the as-grown films were investigated. ... Keywords: Ag, Electrical and optical properties, Thin films, ZnO

D. R. Sahu

2007-12-01T23:59:59.000Z

145

Highly Conductive Textured Molybdenum Doped Indium Oxide Thin Films  

DOE Green Energy (OSTI)

We report on the pulsed laser deposition (PLD) of Mo-doped indium oxide (IMO) films with mobilities of up to 125 cm2/Vsec. Films have been grown from targets with 1-4 wt.% molybdenum. The optimum electrical and optical properties were obtained with the 2% target and yielded a maximum conductivity of 3717 S/cm with mobilities of 99 cm2/V-sec on (100) yttria stabilized zirconia (YSZ) single crystal substrates. Films also exhibit greater than 90% transparency in the visible range. Compared to commercial indium tin oxide (ITO) films, these PLD-grown IMO films have similar conductivity but since they have substantially higher mobility they have a correspondingly lower carrier concentration. The lower carrier concentration should extend the infrared window of the transparency for films of the same conductivity. This may lead to improved performance in a number of applications requiring improved performance TCOs.

Warmsingh, C.; Yoshida, Y.; Readey, D.; Perkins, J.; Parilla, P.; Teplin, C.; Kaydanova, T.; Alleman, J.; Gedvilas, L.; Keyes, B.; Gessert, T.; Coutts, T.; Ginley, D.

2003-05-01T23:59:59.000Z

146

Physical Properties of HWCVD Microcrystalline Silicon Thin Films: Preprint  

DOE Green Energy (OSTI)

This conference paper describes Microcrystalline silicon films were grown with different thicknesses and different hydrogen dilution ratios on glass and Si substrates. Some films were deposited with a seed layer, whereas others were deposited directly on the substrate. We used atomic force microscopy, scanning electron microscopy, and X-ray diffraction to study the morphology and crystalline structure of the samples. We did not find a significant influence of the different substrates on the morphology or crystalline structure. The presence of the seed layer enhanced the crystallization process, decreasing the amount of amorphous layer present in the films. The microstructure of most films was formed by grains, with a subgrain structure. Films grown with low values of dilution ratio had (220) texture and elongated grains, whereas films deposited with high values of dilution ratio were randomly oriented and had an irregular shape.

Moutinho, H. R.; Romero, M. J.; Jiang, C. S.; Xu, Y.; Nelson, B. P.; Jones, K. M.; Mahan, A. H.; Al-Jassim, M. M.

2002-05-01T23:59:59.000Z

147

Thermoplastic Composite with Vapor Grown Carbon Fiber.  

E-Print Network (OSTI)

??Vapor grown carbon fiber (VGCF) is a new class of highly graphitic carbon nanofiber and offers advantages of economy and simpler processing over continuous-fiber composites.… (more)

Lee, Jaewoo

2005-01-01T23:59:59.000Z

148

Ab initio study on noncompensated CrO codoping of GaN for enhanced solar energy conversion  

SciTech Connect

We describe a novel photocatalyst obtained by codoping GaN with CrO, according to a new "noncompensated" codoping concept based on first-principles calculations. The approach enables controllable narrowing of the GaN band gap with significantly enhanced carrier mobility and photocatalytic activity in the visible light region and thus offers immense potential for application in solar energy conversion, water splitting, and a variety of solar-assisted photocatalysis. Our calculations indicate that the formation energy for the cation doping is greatly reduced by noncompensated codoping with an anion. Although Cr doping alone can split the band gap with the formation of an intermediate band, the mobility is low due to carrier trapping by the localized states. The first-principles calculations also demonstrate that CrO codoping of GaN shifts the Fermi level into the conduction band resulting in high carrier density and mobility.

Pan, Hui [ORNL; Gu, Baohua [ORNL; Eres, Gyula [ORNL; Zhang, Zhenyu [ORNL

2010-03-01T23:59:59.000Z

149

Development of a Bulk GaN Growth Technique for Low Defect Density, Large-Area Native Substrates  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

the Electrochemical Solution the Electrochemical Solution Growth (ESG) Technique for Native GaN Substrates DOE Energy Storage & Power Electronics Research Program 30 September 2008 PI: Karen Waldrip Advanced Power Sources R&D, Dept 2546 PM: Stan Atcitty, John Boyes Sandia National Laboratories, Albuquerque, NM, 87185 Sponsor: Gil Bindewald, DOE Power Electronics & Energy Storage Program Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. Outline * Motivation * Existing GaN Growth Technique - Epitaxial Lateral Overgrowth - Methods for Growing Bulk GaN * Development of the Electrochemical Solution Growth Technique

150

Nanocomposite films  

DOE Patents (OSTI)

A thin-film composition of nanocrystal molybdenum in an amorphous metallic matrix may be formed by co-sputtering Mo with aluminum or nickel. NEMS cantilevers may be formed from the film. The films exhibit high nanoindentation hardness and a reduction in roughness and intrinsic stress, while maintaining resistivity in the metallic range.

Mitlin, David (Edmonton, CA); , Ophus, Colin (Edmonton, CA); Evoy, Stephane (Edmonton, CA); Radmilovic, Velimir (Piedmont, CA); Mohammadi, Reza (Edmonton, CA); Westra, Ken (Edmonton, CA); Nelson-Fitzpatrick, Nathaniel (Edmonton, CA); Lee, Zonghoon (Albany, CA)

2010-07-20T23:59:59.000Z

151

Argonne CNM News: STM of individual grains in CVD-grown graphene  

NLE Websites -- All DOE Office Websites (Extended Search)

STM of individual grains in CVD-grown graphene STM of individual grains in CVD-grown graphene SEM of 3d supercrystals The first scanning tunneling microscopy (STM) images of graphene synthesized on copper foil. (b-d) show atomic-resolution images at various locations of the large graphene domain shown in (a). NMAT June 2011 Users from Purdue University, working collaboratively with staff in the Electronic & Magnetic Materials & Devices Group, studied CVD-grown graphene on polycrystalline copper foil for the first time at the atomic-scale. The ultrahigh vacuum scanning tunneling microscopy (UHV-STM) findings performed at the Center for Nanoscale Materials (CNM) will help to guide the optimization of synthesis towards defect-free graphene. The focus of this study was to investigate the quality of the films and

152

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

Science Conference Proceedings (OSTI)

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.

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

2012-01-01T23:59:59.000Z

153

W and WSi(x) Ohmic Contacts on p- And n-Type GaN  

SciTech Connect

W and WSi ohmic contacts on both p- and n-type GaN have been annealed at temperatures from 300-1000 *C. There is minimal reaction (< 100 ~ broadening of the metal/GaN interface) even at 1000 *C. Specific contact resistances in the 10-5 f2-cm2 range are obtained for WSiX on Si-implanted GaN with a peak doping concentration of- 5 x 1020 cm-3, after annealing at 950 `C. On p-GaN, leaky Schottky diode behavior is observed for W, WSiX and Ni/Au contacts at room temperature, but true ohmic characteristics are obtained at 250 - 300 *C, where the specific contact resistances are typically in the 10-2 K2-cm2 range. The best contacts for W and WSiX are obtained after 700 *C annealing for periods of 30- 120 sees. The formation of &WzN interracial phases appear to be important in determining the contact quality.

Abernathy, C.R.; Cao, X.A.; Eizenberg, M.; Han, J.; Lothian, J.R.; Pearton, S.J.; Ren, F.; Shul, R.J.; Zeitouny, A.; Zolper, J.C.

1998-10-13T23:59:59.000Z

154

Atomistic simulation of damage production by atomic and molecular ion irradiation in GaN  

Science Conference Proceedings (OSTI)

We have studied defect production during single atomic and molecular ion irradiation having an energy of 50 eV/amu in GaN by molecular dynamics simulations. Enhanced defect recombination is found in GaN, in accordance with experimental data. Instantaneous damage shows non-linearity with different molecular projectile and increasing molecular mass. Number of instantaneous defects produced by the PF{sub 4} molecule close to target surface is four times higher than that for PF{sub 2} molecule and three times higher than that calculated as a sum of the damage produced by one P and four F ion irradiation (P+4 Multiplication-Sign F). We explain this non-linearity by energy spike due to molecular effects. On the contrary, final damage created by PF{sub 4} and PF{sub 2} shows a linear pattern when the sample cools down. Total numbers of defects produced by Ag and PF{sub 4} having similar atomic masses are comparable. However, defect-depth distributions produced by these species are quite different, also indicating molecular effect.

Ullah, M. W.; Kuronen, A.; Nordlund, K.; Djurabekova, F. [Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki (Finland); Karaseov, P. A.; Titov, A. I. [St. Petersburg State Polytechnic University, 195251 St. Petersburg (Russian Federation)

2012-08-15T23:59:59.000Z

155

High external quantum efficiency and fill-factor InGaN/GaN heterojunction solar cells grown by NH{sub 3}-based molecular beam epitaxy  

SciTech Connect

High external quantum efficiency (EQE) p-i-n heterojunction solar cells grown by NH{sub 3}-based molecular beam epitaxy are presented. EQE values including optical losses are greater than 50% with fill-factors over 72% when illuminated with a 1 sun AM0 spectrum. Optical absorption measurements in conjunction with EQE measurements indicate an internal quantum efficiency greater than 90% for the InGaN absorbing layer. By adjusting the thickness of the top p-type GaN window contact layer, it is shown that the short-wavelength (<365 nm) quantum efficiency is limited by the minority carrier diffusion length in highly Mg-doped p-GaN.

Lang, J. R.; Hurni, C. A.; Cruz, S. C.; Matioli, E.; Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Neufeld, C. J.; Mishra, U. K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

2011-03-28T23:59:59.000Z

156

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

E-Print Network (OSTI)

cm ?3 corresponding to p-type ?lm conductivi- ties as highOF APPLIED PHYSICS 100, 063707 ?2006? Growth of p-type andn-type m-plane GaN by molecular beam epitaxy M. McLaurin, a?

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

2006-01-01T23:59:59.000Z

157

Ferromagnetism in Mn-Implanted Epitaxially Grown Ge on Si(100)  

SciTech Connect

We have studied ferromagnetism of Mn-implanted epitaxial Ge films on silicon. The Ge films were grown by ultrahigh vacuum chemical vapor deposition using a mixture of germane (GeH{sub 4}) and methylgermane (CH{sub 3}GeH{sub 3}) gases with a carbon concentration of less than 1 at. %, and observed surface rms roughness of 0.5 nm, as measured by atomic force microscopy. Manganese ions were implanted in epitaxial Ge films grown on Si (100) wafers to an effective concentration of 16, 12, 6, and 2 at. %. Superconducting quantum interference device measurements showed that only the three highest Mn concentration samples are ferromagnetic, while the fourth sample, with [Mn] = 2 at. %, is paramagnetic. X-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements indicate that localized Mn moments are ferromagnetically coupled below the Curie temperature. Isothermal annealing of Mn-implanted Ge films with [Mn] = 16 at. % at 300 C for up to 1200 s decreases the magnetization but does not change the Curie temperature, suggesting that the amount of the magnetic phase slowly decreases with time at this anneal temperature. Furthermore, transmission electron microscopy and synchrotron grazing incidence x-ray diffraction experiments show that the Mn-implanted region is amorphous, and we believe that it is this phase that is responsible for the ferromagnetism. This is supported by our observation that high-temperature annealing leads to recrystallization and transformation of the material into a paramagnetic phase.

Guchhait, S.; Jamil, M.; Ohldag, H.; Mehta, A.; Arenholz, E.; Lian, G.; Li Fatou, A.; Ferrer, D. A.; Markert, J. T.; Colombo, L.; Banerjee, S. K.

2011-01-05T23:59:59.000Z

158

Anodic films  

DOE Green Energy (OSTI)

Surface layers are formed on many metals by anodic reaction. Such layers include the products of charge and discharge in many storage batteries, dielectric films used in electronic and optical circuits and display devices, layers responsible for passivity and corrosion protection, and films generated in metal shaping and finishing operations such as anodization, coloring, electropolishing, electrochemical machining and deburring. Anodic films are formed by solid-solid transformations or by dissolution-precipitation processes. Film properties and mechanisms of formation can be determined in situ by a number of optical techniques which have recently become available.

Muller, R.H.

1983-08-01T23:59:59.000Z

159

Ammothermal Growth of Gan Substrates For Leds: High-Pressure Ammonothermal Process for Bulk Gallium Nitride Crystal Growth for Energy Efficient Commercially Competitive Lighting  

Science Conference Proceedings (OSTI)

Broad Funding Opportunity Announcement Project: The new GaN crystal growth method is adapted from that used to grow quartz crystals, which are very inexpensive and represent the second-largest market for single crystals for electronic applications (after silicon). More extreme conditions are required to grow GaN crystals and therefore a new type of chemical growth chamber was invented that is suitable for large-scale manufacturing. A new process was developed that grows GaN crystals at a rate that is more than double that of current processes. The new technology will enable GaN substrates with best-in-world quality at lowest-in-world prices, which in turn will enable new generations of white LEDs, lasers for full-color displays, and high-performance power electronics.

None

2011-01-01T23:59:59.000Z

160

Temperature-Dependence of Exciton Radiative Recombination in (Al,Ga)N/GaN Quantum Wells Grown on a-Plane GaN Substrates  

E-Print Network (OSTI)

5221, 34095 Montpellier, France E-mail: pmc53@cam.ac.uk Received October 12, 2012; accepted November 22, 2012; published online May 20, 2013 This article presents the dynamics of excitons in a-plane (Al,Ga)N/GaN single quantum wells of various...

Corfdir, Pierre; Dussaigne, Amélie; Teisseyre, Henryk; Suski, Tadeusz; Grzegory, Izabella; Lefebvre, Pierre; Giraud, Etienne; Shahmohammadi, Mehran; Phillips, Richard; Ganière, Jean-Daniel; Grandjean, Nicolas; Deveaud, Benoît

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Accelerated Publication: Drain current enhancement and negligible current collapse in GaN MOSFETs with atomic-layer-deposited HfO2 as a gate dielectric  

Science Conference Proceedings (OSTI)

Accumulation-type GaN metal-oxide-semiconductor field-effect-transistors (MOSFET's) with atomic-layer-deposited HfO"2 gate dielectrics have been fabricated; a 4@mm gate-length device with a gate dielectric of 14.8nm in thickness (an equivalent SiO"2 ... Keywords: Atomic layer deposition (ALD), Current collapse, GaN, HfO2, Metal-oxide-semiconductor field-effect-transistor (MOSFET)

Y. C. Chang; W. H. Chang; Y. H. Chang; J. Kwo; Y. S. Lin; S. H. Hsu; J. M. Hong; C. C. Tsai; M. Hong

2010-11-01T23:59:59.000Z

162

Influence of the adatom diffusion on selective growth of GaN nanowire regular arrays  

Science Conference Proceedings (OSTI)

Molecular beam epitaxy (MBE) on patterned Si/AlN/Si(111) substrates was used to obtain regular arrays of uniform-size GaN nanowires (NWs). The silicon top layer has been patterned with e-beam lithography, resulting in uniform arrays of holes with different diameters (d{sub h}) and periods (P). While the NW length is almost insensitive to the array parameters, the diameter increases significantly with d{sub h} and P till it saturates at P values higher than 800 nm. A diffusion induced model was used to explain the experimental results with an effective diffusion length of the adatoms on the Si, estimated to be about 400 nm.

Gotschke, T.; Schumann, T.; Limbach, F.; Calarco, R. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Juelich GmbH and JARA-Fundamentals of Future Information Technology (FIT), 52425 Juelich (Germany); Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Stoica, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Juelich GmbH and JARA-Fundamentals of Future Information Technology (FIT), 52425 Juelich (Germany)

2011-03-07T23:59:59.000Z

163

Ultrashort pulse laser deposition of thin films  

DOE Patents (OSTI)

Short pulse PLD is a viable technique of producing high quality films with properties very close to that of crystalline diamond. The plasma generated using femtosecond lasers is composed of single atom ions with no clusters producing films with high Sp.sup.3 /Sp.sup.2 ratios. Using a high average power femtosecond laser system, the present invention dramatically increases deposition rates to up to 25 .mu.m/hr (which exceeds many CVD processes) while growing particulate-free films. In the present invention, deposition rates is a function of laser wavelength, laser fluence, laser spot size, and target/substrate separation. The relevant laser parameters are shown to ensure particulate-free growth, and characterizations of the films grown are made using several diagnostic techniques including electron energy loss spectroscopy (EELS) and Raman spectroscopy.

Perry, Michael D. (Livermore, CA); Banks, Paul S. (Livermore, CA); Stuart, Brent C. (Fremont, CA)

2002-01-01T23:59:59.000Z

164

Growth and Characterization of LiCoO? Thin Films for Microbatteries  

E-Print Network (OSTI)

LiCoO?thin films have been grown by pulsed laser deposition on stainless steel and SiO?/Si substrates. The film deposited at 600°C in an oxygen partial pressure of 100mTorr shows an excellent crystallinity, stoichiometry ...

Hui, Xia

165

Analysis of defects at the interface between high-k thin films and (100) silicon  

Science Conference Proceedings (OSTI)

Paramagnetic defects in atomic layer deposition grown aluminium oxide thin films have been studied using electron paramagnetic resonance. Initial spectra indicate the presence of Si-db, P"b"0 and P"b"1 defects, previously observed in Si/SiO"2 structures. ... Keywords: Aluminium oxide, Defects, EPR, High-k, Interfaces, Thin films

B. J. Jones; R. C. Barklie

2005-06-01T23:59:59.000Z

166

Phase transition on CdSe thin films by changing the volume concentration of Se  

Science Conference Proceedings (OSTI)

In this work CdSe thin films were grown by chemical bath deposition (CBD)6 onto glass substrate with approximately 2000 Å thickness. The samples have been prepared by changing the volume concentration of the solution in the range of 5-45 ... Keywords: CdSe, thin films, chemical bath, phase transitions, semiconductors

M. Rubín; J. I. Cortez; H. Juárez; E. Rosendo; T. Díaz; G. García Salgado; I. Villaverde; R. Lozada-Morales; O. Portillo-Moreno; O. Zelaya-Ngel

2007-07-01T23:59:59.000Z

167

Efficient Switches for Solar Power Conversion: Four Quadrant GaN Switch Enabled Three Phase Grid-Tied Microinverters  

Science Conference Proceedings (OSTI)

Solar ADEPT Project: Transphorm is developing power switches for new types of inverters that improve the efficiency and reliability of converting energy from solar panels into useable electricity for the grid. Transistors act as fast switches and control the electrical energy that flows in an electrical circuit. Turning a transistor off opens the circuit and stops the flow of electrical current; turning it on closes the circuit and allows electrical current to flow. In this way a transistor can be used to convert DC from a solar panel into AC for use in a home. Transphorm’s transistors will enable a single semiconductor device to switch electrical currents at high-voltage in both directions—making the inverter more compact and reliable. Transphorm is using Gallium Nitride (GaN) as a semiconductor material in its transistors instead of silicon, which is used in most conventional transistors, because GaN transistors have lower losses at higher voltages and switching frequencies.

None

2012-02-13T23:59:59.000Z

168

Transport studies on CVD-grown graphene  

E-Print Network (OSTI)

In this thesis, we report transport studies performed on CVD-grown graphene. We perform resistivity and hall measurements on a large-area sample at 4' K. We measure the carrier mobility of the sample and find it to be on ...

Huntley, Miriam Hanna

2009-01-01T23:59:59.000Z

169

Polymer films  

DOE Patents (OSTI)

A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

Granick, Steve (Champaign, IL); Sukhishvili, Svetlana A. (Maplewood, NJ)

2008-12-30T23:59:59.000Z

170

Photonic crystal laser lift-off GaN light-emitting diodes Aurlien David,a  

E-Print Network (OSTI)

Photonic crystal laser lift-off GaN light-emitting diodes Aurélien David,a Tetsuo Fujii,b Brendan March 2006 We report on the fabrication and study of laser lift-off GaN-based light-emitting diodes-state lighting. However, as is the case for any light-emitting diode LED , light tends to be trapped in the high

Recanati, Catherine

171

Symmetry Breaking in Few Layer Graphene Films  

SciTech Connect

Recently, it was demonstrated that the quasiparticledynamics, the layer-dependent charge and potential, and the c-axisscreening coefficient could be extracted from measurements of thespectral function of few layer graphene films grown epitaxially on SiCusing angle-resolved photoemission spectroscopy (ARPES). In this articlewe review these findings, and present detailed methodology for extractingsuch parameters from ARPES. We also present detailed arguments againstthe possibility of an energy gap at the Dirac crossing ED.

Bostwick, A.; Ohta, T.; McChesney, J.L.; Emtsev, K.; Seyller,Th.; Horn, K.; Rotenberg, E.

2007-05-25T23:59:59.000Z

172

Epitaxial Thin Film Silicon Solar Cells Fabricated by Hot Wire Chemical Vapor Deposition Below 750 ..deg..C: Preprint  

Science Conference Proceedings (OSTI)

We report on fabricating film c-Si solar cells on Si wafer templates by hot-wire chemical vapor deposition. These devices, grown at glass-compatible temperatures 500 mV and efficiencies > 5%.

Alberi, K.; Martin, I. T.; Shub, M.; Teplin, C. W.; Iwaniczko, E.; Xu, Y.; duda, A.; Stradin, P.; Johnston, S. W.; Romero, M. J.; Branz, H. M.; Young, D. L.

2009-06-01T23:59:59.000Z

173

Transistors for Electric Motor Drives: High-Performance GaN HEMT Modules for Agile Power Electronics  

SciTech Connect

ADEPT Project: Transphorm is developing transistors with gallium nitride (GaN) semiconductors that could be used to make cost-effective, high-performance power converters for a variety of applications, including electric motor drives which transmit power to a motor. A transistor acts like a switch, controlling the electrical energy that flows around an electrical circuit. Most transistors today use low-cost silicon semiconductors to conduct electrical energy, but silicon transistors don’t operate efficiently at high speeds and voltage levels. Transphorm is using GaN as a semiconductor material in its transistors because GaN performs better at higher voltages and frequencies, and it is more energy efficient than straight silicon. However, Transphorm is using inexpensive silicon as a base to help keep costs low. The company is also packaging its transistors with other electrical components that can operate quickly and efficiently at high power levels—increasing the overall efficiency of both the transistor and the entire motor drive.

None

2010-09-01T23:59:59.000Z

174

Growth of gadolinium oxide films for advanced MOS structure  

Science Conference Proceedings (OSTI)

We have investigated properties of insulating gadolinium oxide (Gd"2O"3) films in connection with the replacement of silicon oxide (SiO"2) gate dielectrics in new generation of CMOS devices. The Gd"2O"3 layers were grown using metal organic chemical ... Keywords: Gadolinium oxide, High-? dielectric, MOCVD, MOS structure

R. Lupták; K. Fröhlich; A. Rosová; K. Hušeková; M. apajna; D. Machajd?k; M. Jergel; J. P. Espinós; C. Mansilla

2005-06-01T23:59:59.000Z

175

Boron arsenide thin film solar cell development. Quarterly report No. 1  

DOE Green Energy (OSTI)

A large portion of the effort expended in the first quarter was devoted to the design, assembly, and testing of the film growth apparatus. The reactor has been completed and tested by depositing boron from diborane gas onto heated quartz substrates. The objective of this effort was to achieve film growth, which has been accomplished. Within the last month, attempts to grow boron arsenide films have been made by introducing both diborane and arsine into the reactor. Thin films have been grown on quartz and sapphire (alumina) substrates. Variations in film thickness, composition, degree of crystallinity, and conductivity have been observed as a result of variation of the deposition parameters, such as type and flow rate of carrier gases, substrate temperature, and substrate materials. X-ray analysis of several samples indicates that films containing boron and arsenic have been grown. No crystalline films have been produced to date. Electrical and optical measurements indicate some correlation between at least one of the films grown and the results achieved by Chu, et al. on BAs. Thus far, the electrical conductivity, film topography, optical absorption, index of refraction, impurity type, and photo-conductivity have been investigated on one sample. This material appears to be B/sub x/As/sub y/ and could be BAs. Further investigations will be required to be conclusive.

Boone, J.L.; Van Doren, T.P.

1979-07-01T23:59:59.000Z

176

Oxygen off-stoichiometry and phase separation in EuO thin films  

Science Conference Proceedings (OSTI)

We report on our study on the influence of the growth conditions on the europium/oxygen stoichiometry, morphology, magnetic properties, and electrical conductivity of EuO thin films. SQUID magnetometry and x-ray photoelectron spectroscopy were utilized as complementary techniques to determine the oxygen content of EuO{sub 1{+-}x} thin films grown by molecular beam epitaxy with and without the employment of the so-called Eu distillation process. We found indications for phase separation to occur in Eu-rich as well as in over-oxidized EuO for films grown at substrate temperatures below the Eu distillation temperature. Only a fraction of the excess Eu contributes to the metal-insulator transition in Eu-rich films grown under these conditions. We also observed that the surfaces of these films were ill defined and may even contain more Eu excess than the film average. Only EuO films grown under distillation conditions are guaranteed to have the same magnetic and electrical properties as stoichiometric bulk EuO, and to have surfaces with the proper Eu/O stoichiometry and electronic structure.

Altendorf, S. G.; Efimenko, A.; Oliana, V. [II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, DE-50937 Koeln (Germany); Max Planck Institute for Chemical Physics of Solids, Noethnitzerstr. 40, DE-01187 Dresden (Germany); Kierspel, H. [II. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, DE-50937 Koeln (Germany); Rata, A. D.; Tjeng, L. H. [Max Planck Institute for Chemical Physics of Solids, Noethnitzerstr. 40, DE-01187 Dresden (Germany)

2011-10-15T23:59:59.000Z

177

Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)  

SciTech Connect

Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel [National Institute of Physics, University of the Philippines Diliman, Quezon City 1101 (Philippines); Que, Christopher T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila 1004 (Philippines); Yamamoto, Kohji; Tani, Masahiko [Research Center for Development of Far-Infrared Region, University of Fukui, Fukui 910-8507 (Japan)

2012-12-15T23:59:59.000Z

178

Pulsed laser processing of high temperature superconducting thin films  

SciTech Connect

Systematic studies of the effects of pulsed laser deposition processing parameters on plume dynamics and resultant film properties have been performed. Plume angular distributions, cos{sup m}({theta}), were observed to be variable between 1 > m > 10 depending on laser energy density and spot size. Under optimized conditions, epitaxial, superconducting thin films could be grown in-situ on a variety of single-crystal substrates. High quality, 200 nm thick films were obtained at deposition rates approaching 15 nm/sec. Additionally, the patterning of YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films has been achieved by a process which combines thermal oxygen diffusion and laser annealing. This process is performed under relatively mild conditions which allows the structural integrity of the films to be preserved. 9 refs., 6 figs.

Muenchausen, R.E.; Dye, R.C.; Estler, R.C.; Foltyn, S.; Garcia, A.R.; Hubbard, K.M.; Nogar, N.S.; Wu, X.D. (Los Alamos National Lab., NM (USA)); Carim, A.; Mukherjee, A.; Brueck, S.R.J. (New Mexico Univ., Albuquerque, NM (USA))

1990-01-01T23:59:59.000Z

179

Spectroscopic Analysis of Impurity Precipitates in CdS Films  

DOE Green Energy (OSTI)

Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR), Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

Webb, J. D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D. S.; Noufi, R.

1999-10-31T23:59:59.000Z

180

Ohmic contacts to single-crystalline 3C-SiC films for extreme-environment MEMS applications  

Science Conference Proceedings (OSTI)

This paper describes the ohmic contacts to single-crystalline 3C-SiC thin films heteroepitaxially grown on Si (001) wafers. In this work, a TiW (titanium-tungsten) film was deposited as a contact material by RF magnetron sputter and annealed through ... Keywords: Contact resistivity, Ohmic contact, Single-crystalline 3C-SiC, TiW

Gwiy-Sang Chung; Kyu-Hyung Yoon

2008-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Ga{sub 1-x}Mn{sub x}N epitaxial films with high magnetization  

Science Conference Proceedings (OSTI)

We report on the fabrication of pseudomorphic wurtzite Ga{sub 1-x}Mn{sub x}N grown on GaN with Mn concentrations up to 10% using molecular beam epitaxy. According to Rutherford backscattering, the Mn ions are mainly at the Ga-substitutional positions, and they are homogeneously distributed according to depth-resolved Auger-electron spectroscopy and secondary-ion mass-spectroscopy measurements. A random Mn distribution is indicated by transmission electron microscopy, and no Mn-rich clusters are present for optimized growth conditions. A linear increase of the c-lattice parameter with increasing Mn concentration is found using x-ray diffraction. The ferromagnetic behavior is confirmed by superconducting quantum-interference measurements showing saturation magnetizations of up to 150 emu/cm{sup 3}.

Kunert, G.; Kruse, C.; Figge, S.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, D-28359 Bremen (Germany); Dobkowska, S.; Jakiela, R.; Stefanowicz, W.; Sawicki, M. [Institute of Physics, Polish Academy of Science, PL-02-668 Warszawa (Poland); Li, Tian; Bonanni, A. [Institute for Semiconductor and Solid State Physics, Johannes Kepler University Linz, A 4040 Linz (Austria); Reuther, H.; Grenzer, J.; Borany, J. von [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden (Germany); Dietl, T. [Institute of Physics, Polish Academy of Science, PL-02-668 Warszawa (Poland); Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, PL-00-681 Warszawa (Poland)

2012-07-09T23:59:59.000Z

182

Growth mechanisms and characterization of hydrogenated amorphous- silicon-alloy films  

Science Conference Proceedings (OSTI)

This report describes an apparatus, constructed and tested, that allows measurement of the surface morphology of as-grown hydrogenated amorphous silicon films with atomic resolution using a scanning tunneling microscope. Surface topologies of 100-[degree][Lambda]-thick intrinsic films, deposited on atomically flat, crystalline Si and GaAs, are reported. These films surfaces are relatively flat on the atomic scale, indicating fairly homogeneous, compact initial film growth. The effect of probe-tip size on the observed topology and the development of atomically sharp probes is discussed. 17 refs, 9 figs.

Gallagher, A.; Ostrom, R.: Stutzin, G.; Tanenbaum, D. (National Inst. of Standards and Technology, Gaithersburg, MD (United States))

1993-02-01T23:59:59.000Z

183

Effects of Different Precursor's Concentration on the Properties of Zinc Oxide Thin Films  

Science Conference Proceedings (OSTI)

Zinc oxide (ZnO) thin films were successfully grown on silicon substrate with different molarities, by a sol-gel method. In the process, the molarities were varied from 0.2-1.0 M and it was found that increasing in molarities had affected the structure of ZnO thin films. The properties of the thin films were characterized and studied by ultraviolet-visible spectroscopy (UV-Vis) and photoluminescence spectrometer (PL). It was found that the molarities affect the optical properties of the resultant ZnO thin films.

Malek, M. F.; Zakaria, N.; Sahdan, M. Z.; Mamat, M. H. [Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z. [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Rusop, M. [Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

2010-07-07T23:59:59.000Z

184

Reentrant Insulating State in Ultrathin Manganite Films  

SciTech Connect

The transport and magnetic properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin-films grown by pulsed laser deposition on (LaAlO{sub 3}){sub 0.3}(SrAl{sub 0.5}Ta{sub 0.5}O{sub 3}){sub 0.7} single crystal substrates have been investigated. A systematic series with various thicknesses of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} was used to establish a phase diagram - which showed a clear difference compared to films grown on SrTiO{sub 3} substrates, highlighting the importance of film thickness and substrate strain. At 8 unit cells, the boundary between the metallic and insulating ground states, a second abrupt metal-insulator transition was observed at low temperatures, which could be tuned with by magnetic field, and is interpreted as a signature of electronic phase separation.

Bell, Christopher

2011-08-11T23:59:59.000Z

185

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

DOE Green Energy (OSTI)

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

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

1996-04-01T23:59:59.000Z

186

Superstructure of self-aligned hexagonal GaN nanorods formed on nitrided Si(111) surface  

SciTech Connect

We present here the spontaneous formation of catalyst-free, self-aligned crystalline (wurtzite) nanorods on Si(111) surfaces modified by surface nitridation. Nanorods grown by molecular beam epitaxy on bare Si(111) and non-stoichiometric silicon nitride interface are found to be single crystalline but disoriented. Those grown on single crystalline Si{sub 3}N{sub 4} intermediate layer are highly dense c-oriented hexagonal shaped nanorods. The morphology and the self-assembly of the nanorods shows an ordered epitaxial hexagonal superstructure, suggesting that they are nucleated at screw dislocations at the interface and grow spirally in the c-direction. The aligned nanorod assembly shows high-quality structural and optical emission properties.

Kumar, Praveen; Tuteja, Mohit; Kesaria, Manoj; Waghmare, U. V.; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064 (India)

2012-09-24T23:59:59.000Z

187

CARS of Thin Films  

Science Conference Proceedings (OSTI)

... as a thin film diagnostic. Surface enhanced Raman scattering, SERS, has been used to probe the interfacial region of thin polymer films on metal ...

2012-10-02T23:59:59.000Z

188

Thin Films at Interfaces  

Science Conference Proceedings (OSTI)

... internal structure of these films was probed ... provided important information on film composition and ... The PEO polymers form thin adsorbed layers ...

189

Czochralski Grown Ce,Gd:YAG Single Crystals  

Science Conference Proceedings (OSTI)

In this work we propose a new concept of white LED, based on the single crystal phosphor plates (SCPPs) of Czochralski grown Ce,Gd:YAG single crystal.

190

High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films  

Science Conference Proceedings (OSTI)

A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

R. Farrell; V. R. Pagan; A. Kabulski; Sridhar Kuchibhatl; J. Harman; K. R. Kasarla; L. E. Rodak; P. Famouri; J. Peter Hensel; D. Korakakis

2008-05-01T23:59:59.000Z

191

High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films  

Science Conference Proceedings (OSTI)

A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE-grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

Farrell, R.; Pagan, V.R.; Kabulski, A.; Kuchibhatla, S.; Harman, J.; Kasarla, K.R.; Rodak, L.E.; Hensel, J.P.; Famouri, P.; Korakakis, D.

2008-01-01T23:59:59.000Z

192

DD10, Characterization of L2 1  

Science Conference Proceedings (OSTI)

E3, A Compensation Mechanism for Flexible and Electrically Stable ... EE2, Following Charge-Trapping Chemical Reactions in Pentacene Films by Selective Chemical .... on Polar, Nonpolar, and Semipolar GaN Orientations Grown by Ammonia MBE ... JJ5, The Electrical Nature of Structural Defects in InSb Synthesized by ...

193

High efficiency cadmium and zinc telluride-based thin film solar cells  

DOE Green Energy (OSTI)

Polycrystalline Cd{sub 1-x}Zn{sub x}Te and Cd{sub 1-x}Mn{sub x}Te films with a band gap of 1.7 eV were successfully grown on glass/SnO{sub 2}/CdS substrates by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD), respectively. Polycrystalline Cd{sub 1-x}Zn{sub x}Te films grown by MBE resulted in uniform composition and sharp interfaces. However, polycrystalline Cd{sub 1-x}Mn{sub x}Te films grown by MOCVD showed nonuniform compositions and evidence of manganese accumulation at the Cd{sub 1-x}Mn{sub x}Te/CdS interface. We found that manganese interdiffuses and replaces cadmium in the CdS film. By improving the CdTe/CdS interface and, thus, reducing the collection function effects, the efficiency of the MOCVD CdTe cell can be improved to about 13.5%. MBE-grown CdTe cells also produced 8%--9% efficiencies. The standard CdTe process was not optimum for ternary films and resulted in a decrease in the band gap. Recent results indicate that CdCl{sub 2} + ZnCl{sub 2} chemical treatment may prevent the band-gap reduction, and that chromate etch (rather than bromine etch) may provide the solution to contact resistance in the ternary cells.

Rohatgi, A.; Summers, C.J.; Erbil, A.; Sudharsanan, R.; Ringel, S. (Georgia Inst. of Tech., Atlanta, GA (USA). School of Electrical Engineering)

1990-10-01T23:59:59.000Z

194

Structure determination of thin CoFe films by anomalous x-ray diffraction  

Science Conference Proceedings (OSTI)

This work reports on the investigation of structure-property relationships in thin CoFe films grown on MgO. Because of the very similar scattering factors of Fe and Co, it is not possible to distinguish the random A2 (W-type) structure from the ordered B2 (CsCl-type) structure with commonly used x-ray sources. Synchrotron radiation based anomalous x-ray diffraction overcomes this problem. It is shown that as grown thin films and 300 K post annealed films exhibit the A2 structure with a random distribution of Co and Fe. In contrast, films annealed at 400 K adopt the ordered B2 structure.

Gloskovskii, Andrei; Stryganyuk, Gregory; Ouardi, Siham [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Fecher, Gerhard H.; Felser, Claudia [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden (Germany); Hamrle, Jaroslav; Pistora, Jaromir [Department of Physics and Nanotechnology Centre, VSB-Technical University of Ostrava, 70833 Ostrava (Czech Republic); Bosu, Subrojati; Saito, Kesami; Sakuraba, Yuya; Takanashi, Koki [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan)

2012-10-01T23:59:59.000Z

195

Process for forming silicon carbide films and microcomponents  

DOE Patents (OSTI)

Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C{sub 60} precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C{sub 60} with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C{sub 60} on silicon dioxide at surface temperatures less than 1250 K. 5 figs.

Hamza, A.V.; Balooch, M.; Moalem, M.

1999-01-19T23:59:59.000Z

196

Process for forming silicon carbide films and microcomponents  

DOE Patents (OSTI)

Silicon carbide films and microcomponents are grown on silicon substrates at surface temperatures between 900 K and 1700 K via C.sub.60 precursors in a hydrogen-free environment. Selective crystalline silicon carbide growth can be achieved on patterned silicon-silicon oxide samples. Patterned SiC films are produced by making use of the high reaction probability of C.sub.60 with silicon at surface temperatures greater than 900 K and the negligible reaction probability for C.sub.60 on silicon dioxide at surface temperatures less than 1250 K.

Hamza, Alex V. (Livermore, CA); Balooch, Mehdi (Berkeley, CA); Moalem, Mehran (Berkeley, CA)

1999-01-01T23:59:59.000Z

197

Annealing effect on the giant magnetoresistance of La-Ca-Mn-O thin films  

SciTech Connect

Thin films of perovskite-like (La,Ca)MnO{sub {delta}} with (001) orientation were grown epitaxially on (100) MgO substrates by a simple facing-target sputtering technique. The as-deposited films already possess a significant low field giant magnetoresistance. Further post-annealing experiments on these samples indicate that the high electrical resistivity is not a prerequisite of the giant magnetoresistance effect.

Zeng, X.T.; Wong, H.K. [Chinese Univ. of Hong Kong, Chatin (Hong Kong). Physics Dept.

1995-11-01T23:59:59.000Z

198

Dramatic Role of Critical Current Anisotropy on Flux Avalanches in MgB2 Films J. Albrecht and A. T. Matveev*  

E-Print Network (OSTI)

Dramatic Role of Critical Current Anisotropy on Flux Avalanches in MgB2 Films J. Albrecht and A. T.25.Qt, 74.78.ÿw Above the lower critical field Hc1 magnetic flux pene- trates type-II superconductors) Anisotropic penetration of magnetic flux in MgB2 films grown on vicinal sapphire substrates is investigated

Johansen, Tom Henning

199

Solar Control Thin Films Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

Sputtering equipment Solar Control Thin Films Laboratory The Solar Control Thin Films lab develops novel thin film coatings, deposition technologies, and device systems for...

200

In-situ spectro-microscopy on organic films: Mn-Phthalocyanine on Ag(100)  

SciTech Connect

Metal phthalocyanines are attracting significant attention, owing to their potential for applications in chemical sensors, solar cells and organic magnets. As the electronic properties of molecular films are determined by their crystallinity and molecular packing, the optimization of film quality is important for improving the performance of organic devices. Here, we present the results of in situ low-energy electron microscopy / photoemission electron microscopy (LEEM/PEEM) studies of incorporation-limited growth [1] of manganese-phthalocyanine (MnPc) on Ag(100) surfaces. MnPc thin films were grown on both, bulk Ag(100) surface and thin Ag(100)/Fe(100) films, where substrate spin-polarized electronic states can be modified through tuning the thickness of the Ag film [2]. We also discuss the electronic structure and magnetic ordering in MnPc thin films, investigated by angle- and spin-resolved photoemission spectroscopy.

Al-Mahboob A.; Vescovo, E.; Sadowski, J.T.

2013-08-18T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

A large polarization in Ce-modified bismuth ferrite thin films  

Science Conference Proceedings (OSTI)

Bi{sub 0.95}Ce{sub 0.05}FeO{sub 3} (BCFO) thin films were grown on SrRuO{sub 3}/TiO{sub 2}/SiO{sub 2}/Si(100) substrates via radio frequency sputtering. The BCFO thin film has a (111) orientation with a high phase purity. Improved dielectric behavior is observed for the BCFO thin film as compared with that of pure bismuth ferrite thin film. A large remanent polarization of 2P{sub r} {approx} 183.9 {mu}C/cm{sup 2} is induced in the BCFO thin film, owing to the (111) orientation and the introduction of Ce. The local phase decomposition induced by larger depolarization fields and the oxygen vacancies dominates the fatigue resistance of the BCFO thin film.

Wang Yuanyu [College of Materials Science and Metallurgy Engineering, Guizhou University, Guiyang 550003 (China)

2011-06-15T23:59:59.000Z

202

Solvent-assisted growth of metal phthalocyanine thin films on Au(111)  

Science Conference Proceedings (OSTI)

Thin films of metal phthalocyanine (MPc) are grown on an Au(111) support with a newly developed aerosol molecular beam deposition source and characterized in situ via ultrahigh vacuum scanning tunneling microscopy. MPcs are delivered to Au(111) in a series of N{sub 2}-entrained microsized solvent droplets of variable surface residence time. Phthalocyanine film registration to the herringbone reconstruction of the Au(111) surface, indicative of thermodynamically favored structure, is observed at submonolayer coverages for aromatic solvents with long residence times. Aerosol-deposited monolayer film structures are noncrystalline with tilted MPc orientations and vacancy nanocavities. Upon annealing, MPc molecules adopt flat-lying orientations with respect to the substrate and vacancies are eliminated. Film morphologies indicate solvation-mediated film nucleation and growth, with less long-range ordering that in vapor-generated films.

Tskipuri, Levan; Shao Qian; Reutt-Robey, Janice [Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-4454 (United States)

2012-05-15T23:59:59.000Z

203

ZnO light-emitting diode grown by plasma-assisted metal organic chemical vapor deposition  

SciTech Connect

We report a breakthrough in fabricating ZnO homojunction light-emitting diode by metal organic chemical vapor deposition. Using NO plasma, we are able to grow p-type ZnO thin films on n-type bulk ZnO substrates. The as-grown films on glass substrates show hole concentration of 10{sup 16}-10{sup 17} cm{sup -3} and mobility of 1-10 cm{sup 2} V{sup -1} s{sup -1}. Room-temperature photoluminescence spectra reveal nitrogen-related emissions. A typical ZnO homojunction shows rectifying behavior with a turn-on voltage of about 2.3 V. Electroluminescence at room temperature has been demonstrated with band-to-band emission at I=40 mA and defect-related emissions in the blue-yellow spectrum range.

Xu, W.Z.; Ye, Z.Z.; Zeng, Y.J.; Zhu, L.P.; Zhao, B.H.; Jiang, L.; Lu, J.G.; He, H.P.; Zhang, S.B. [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

2006-04-24T23:59:59.000Z

204

Superlubricity and wearless sliding in diamondlike carbon films.  

DOE Green Energy (OSTI)

Diamondlike carbon (DLC) films have attracted great interest in recent years mainly because of their unusual optical, electrical, mechanical, and tribological properties. Such properties are currently being exploited for a wide range of engineering applications including magnetic hard disks, gears, sliding and roller bearings, scratch resistant glasses, biomedical implants, etc. Systematic studies on carbon-based materials in our laboratory have led to the development of a new class of amorphous DLC films that provide extremely low friction and wear coefficients of 0.001 to 0.005 and 10{sup -11} to 10{sup -10} mm{sup 3} /N.m, respectively, when tested in inert-gas or high-vacuum environments. These films were produced in highly hydrogenated gas discharge plasmas by a plasma enhanced chemical vapor deposition process at room temperature. The carbon source gases used in the deposition of these films included methane, acetylene, and ethylene. Tribological studies in our laboratory have established a very close correlation between the composition of the plasmas and the friction and wear coefficients of the resultant DLC films. Specifically, the friction and wear coefficients of DLC films grown in plasmas with higher hydrogen-to-carbon ratios were much lower than films derived from source gases with lower hydrogen-to-carbon ratios. Fundamental tribological and surface analytical studies have led us to conclude that hydrogen (within the film, as well as on the sliding surfaces) is extremely important for the superlubricity and wearless sliding behavior of these films. Based on these studies, a mechanistic model is proposed to explain the superlow friction and wear properties of the new DLC films.

Erdemir, A.

2001-12-13T23:59:59.000Z

205

Ultralow nonalloyed Ohmic contact resistance to self aligned N-polar GaN high electron mobility transistors by In(Ga)N regrowth  

Science Conference Proceedings (OSTI)

Ultralow Ohmic contact resistance and a self-aligned device structure are necessary to reduce the effect of parasitic elements and obtain higher f{sub t} and f{sub max} in high electron mobility transistors (HEMTs). N-polar (0001) GaN HEMTs, offer a natural advantage over Ga-polar HEMTs, in terms of contact resistance since the contact is not made through a high band gap material [Al(Ga)N]. In this work, we extend the advantage by making use of polarization induced three-dimensional electron-gas through regrowth of graded InGaN and thin InN cap in the contact regions by plasma (molecular beam epitaxy), to obtain an ultralow Ohmic contact resistance of 27 OMEGA mum to a GaN 2DEG.

Dasgupta, Sansaptak; Nidhi,; Brown, David F.; Wu, Feng; Keller, Stacia; Speck, James S.; Mishra, Umesh K. [Department of ECE, University of California, Santa Barbara, California 93106 (United States) and Department of Materials, University of California, Santa Barbara, California 93106 (United States)

2010-04-05T23:59:59.000Z

206

RESONANT MAGNETIC X-RAY SCATTERING FROM IN SITU GROWN HOLMIUM-METAL FILMS  

E-Print Network (OSTI)

by a turbomolecular pump backed by an oil-free turbo/diaphragm pump combination. Together with a Ce sublimatio and outgoing photons, two UHV-compatible Be windows of about 0.5 mm thickness were used. The chamber was pumped

Grigoriev, Alexei

207

The Properties of the ZnINSe Thin Film Grown by SILAR Method  

Science Conference Proceedings (OSTI)

Nanothermites: Unconventional Nanomaterials with High Energy Output · Nitriding Surface Treatments to Improve Water Droplet Erosion Resistance.

208

ZnO Nanowires Grown on ZnO Thin Film Deposited by Atomic Layer ...  

Science Conference Proceedings (OSTI)

In this work the atomic layer deposition (ALD) technique was used to deposit the seeding ... 3D Multiwall Carbon Nanotubes (MWCNTs) for Li-Ion Battery Anode.

209

Molecular-Beam Epitaxially Grown MgB2 Thin Films and Superconducting Tunnel Junctions  

E-Print Network (OSTI)

Since the discovery of its superconducting properties in 2001, magnesium diboride has generated terrific scientific and engineering research interest around the world. With a 𝑇

Laloe, Jean-Baptiste

210

Minirhizotron imaging reveals that nodulation of field-grown...  

NLE Websites -- All DOE Office Websites (Extended Search)

Minirhizotron imaging reveals that nodulation of field-grown soybean is enhanced by free-air CO 2 enrichment only when combined with drought stress Sharon B. Gray A , Reid S....

211

Growth temperature dependence of epitaxial Gd2O3 films on Si(111)  

Science Conference Proceedings (OSTI)

This article reports on the epitaxy of crystalline high @k oxide Gd"2O"3 layers on Si(111) for CMOS gate application. Epitaxial Gd"2O"3 thin films have been grown by Molecular Beam Epitaxy (MBE) on Si(111) substrates between 650 and 750^oC. The structural ... Keywords: Crystalline high ? oxide, Electrical properties, Gd2O3, Molecular beam epitaxy

G. Niu; B. Vilquin; N. Baboux; C. Plossu; L. Becerra; G. Saint-Grions; G. Hollinger

2009-07-01T23:59:59.000Z

212

Effect of charged dislocation walls on mobility in GaN epitaxial layers  

Science Conference Proceedings (OSTI)

A theoretical model in the context of a conventional representation on traditional notion concerning Read cylinders for interpretation of mobility collapse as a function of the concentration of free carriers in GaN-based films is suggested. Along with phonon and impurity scattering mechanisms, electron scattering due to charged dislocations embedded into the walls is taken into account in the model. An expression is obtained for the height of the drift barrier depending on the concentration of free carriers. Based on the derived equations, the dependence of the location of the mobility minimum on the dislocation structure is interpreted.

Krasavin, S. E., E-mail: krasavin@theor.jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

2012-05-15T23:59:59.000Z

213

Epitaxial Crystal Silicon Absorber Layers and Solar Cells Grown at 1.8 Microns per Minute: Preprint  

DOE Green Energy (OSTI)

We have grown device-quality epitaxial silicon thin films at growth rates up to 1.8 ?m/min, using hot-wire chemical vapor deposition from silane at substrate temperatures below 750 degrees C. At these rates, which are more than 30 times faster than those used by the amorphous and nanocrystalline Si industry, capital costs for large-scale solar cell production would be dramatically reduced, even for cell absorber layers up to 10 ?m thick. We achieved high growth rates by optimizing the three key parameters: silane flow, depletion, and filament geometry, based on our model developed earlier. Hydrogen coverage of the filament surface likely limits silane decomposition and growth rate at high system pressures. No considerable deterioration in PV device performance is observed when grown at high rate, provided that the epitaxial growth is initiated at low rate. A simple mesa device structure (wafer/epi Si/a-Si(i)/a-Si:H(p)/ITO) with a 2.3 um epitaxial silicon absorber layer was grown at 700 nm/min. The finished device had an open-circuit voltage of 0.424 V without hydrogenation treatment.

Bobela, D. C.; Teplin, C. W.; Young, D. L.; Branz, H. M.; Stradins, P.

2011-07-01T23:59:59.000Z

214

Synthesis of superlow friction carbon films from highly hydrogenated methane plasmas.  

DOE Green Energy (OSTI)

In this study, we investigated the friction and wear performance of diamondlike carbon films (DLC) derived from increasingly hydrogenated methane plasmas. The films were deposited on steel substrates by a plasma-enhanced chemical vapor deposition process at room temperature and the tribological tests were performed in dry nitrogen. Tests results revealed a close correlation between the hydrogen in source gas plasma and the friction and wear coefficients of the DLC films. Specifically, films grown in plasmas with higher hydrogen-to-carbon ratios had much lower friction coefficients and wear rates than did films derived from source gases with lower hydrogen-to-carbon ratios. The lowest friction coefficient (0.003) was achieved with a film derived from 25% methane--75% hydrogen, while a coefficient of 0.015 was found for films derived from pure methane. Similar correlations were observed for wear rates. Films derived from hydrogen-rich plasmas had the least wear, while films derived from pure methane suffered the highest wear. We used a combination of surface analytical methods to characterize the structure and chemistry of the DLC films and worn surfaces.

Erdemir, A.; Eryilmaz, O. L.; Nilufer, I. B.; Fenske, G. R.

2000-10-13T23:59:59.000Z

215

Correlation between surface chemistry, density and band gap in nanocrystalline WO3 thin films  

Science Conference Proceedings (OSTI)

Nanocrystalline WO3 thin films were produced by sputter-deposition by varying the ratio of argon to oxygen in the reactive gas mixture during deposition. The surface chemistry, physical characteristics, and optical properties of nanocrystalline WO3 films were evaluated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray reflectivity (XRR), and spectrophotometric measurements. The effect of ultra-microstructure was significant on the optical properties of WO3 films. The XPS analyses indicate the formation of stoichiometric WO3 with tungsten existing in fully oxidized valence state (W6+). However, WO3 films grown at high oxygen concentration (>60%) in the sputtering gas mixture were over stoichiometric with excess oxygen. XRR simulations, which are based on isotropic WO3 film - SiO2 interface - Si substrate model, indicate that the density of WO3 films is sensitive to the oxygen content in the sputtering gas. The spectral transmission of the films increased with the increasing oxygen. The band gap of these films increases from 2.78 eV to 3.25 eV with increasing oxygen. A direct correlation between the film-density and band gap in nanocrystalline WO3 films is established based on the observed results.

Vemuri, Venkata Rama Ses; Engelhard, Mark H.; Ramana, C.V.

2012-03-01T23:59:59.000Z

216

Characterization of Thin Films by XAFS: Application to Spintronics Materials  

SciTech Connect

X-ray absorption fine structure (XAFS) has proven very valuable in characterizing thin films. This is illustrated with some examples from the area of diluted magnetic semiconductor (DMS) materials for spintronics applications. A promising route to DMS materials is doping of oxides such as TiO2 and ZnO with magnetic atoms such as Co. These can be grown as epitaxial thin films on various substrates. XAFS is especially valuable for characterizing the dopant atoms. The near edge region is sensitive to the symmetry of the bonding and valence of the dopants, and the extended XAFS can determine the details of the lattice site. XAFS is also valuable for detecting metallic nanoparticles. These can be difficult to detect by other methods, and can give a spurious magnetic signal. The power of XAFS is illustrated by examples from studies on Co doped ZnO films.

Heald, Steve M.; Kaspar, Tiffany C.; Droubay, Timothy; Chambers, Scott A.

2009-10-25T23:59:59.000Z

217

Interface and Electronic Characterization of Thin Epitaxial Co3O4 Films  

Science Conference Proceedings (OSTI)

The interface and electronic structure of thin ({approx} 20-74 nm) Co{sub 3}O{sub 4}(1 1 0) epitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl{sub 2}O{sub 4}(1 1 0) single crystal substrates have been investigated by means of real and reciprocal space techniques. As-grown film surfaces are found to be relatively disordered and exhibit an oblique low energy electron diffraction (LEED) pattern associated with the O-rich CoO{sub 2} bulk termination of the (1 1 0) surface. Interface and bulk film structure are found to improve significantly with post-growth annealing at 820 K in air and display sharp rectangular LEED patterns, suggesting a surface stoichiometry of the alternative Co{sub 2}O{sub 2} bulk termination of the (1 1 0) surface. Non-contact atomic force microscopy demonstrates the presence of wide terraces separated by atomic steps in the annealed films that are not present in the as-grown structures; the step height of {approx}2.7 {angstrom} corresponds to two atomic layers and confirms a single termination for the annealed films, consistent with the LEED results. A model of the (1 x 1) surfaces that allows for compensation of the polar surfaces is presented.

Vaz, C.A.; Zhu, Y.; Wang, H.-Q.; Ahn, C.H.; Henrich, V.E.; Baykara, M.Z.; Schwendemann, T.C.; Pilet, N.; Albers, B.J.; Schwarz, U.D.; Zhang, L.H,; Wang, J.; Altman, E.I.

2009-01-15T23:59:59.000Z

218

Graphene layer growth on silicon substrates with nickel film by pulse arc plasma deposition  

Science Conference Proceedings (OSTI)

Carbon layer has been grown on a Ni/SiO{sub 2}/Si(111) substrate under high vacuum pressure by pulse arc plasma deposition. From the results of Raman spectroscopy for the sample, it is found that graphene was formed by ex-situ annealing of sample grown at room temperature. Furthermore, for the sample grown at high temperature, graphene formation was shown and optimum temperature was around 1000 Degree-Sign C. Transmission electron microscopy observation of the sample suggests that the graphene was grown from step site caused by grain of Ni film. The results show that the pulse arc plasma technique has the possibility for acquiring homogenous graphene layer with controlled layer thickness.

Fujita, K.; Banno, K.; Aryal, H. R.; Egawa, T. [Research Center for Nano-Device and System, Nagoya Institute of Technology, Gokiso-cho, Showa-Ku, Nagoya 466-8555 (Japan)

2012-10-15T23:59:59.000Z

219

XMCD experimental station optimized for ultrathin magnetic films at HiSOR-BL14  

Science Conference Proceedings (OSTI)

We have constructed a system for in situ X-ray magnetic circular dichroism (XMCD) measurements of ultrathin magnetic films at the soft X-ray beamline HiSOR-BL14 at Hiroshima Synchrotron Radiation Center. The XMCD experimental station is directly connected to the beamline, and equipped with a sample fabrication chamber where various types of ultrathin magnetic films can be grown with monatomic layer control. XMCD spectra of the as-grown samples can be measured with adequate precision for the analysis of magnetic moments, under proper control of the light polarization in the beamline optics. This system has enabled the investigation of natural magnetic states in the ultrathin magnetic films without the influence of surface oxidation or any cap-layers.

Sawada, Masahiro; Namatame, Hirofumi [Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hirohisma, Hiroshima 739-0046 (Japan); Ueno, Tetsuro; Tagashira, Tetsuro [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 (Japan); Taniguchi, Masaki [Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hirohisma, Hiroshima 739-0046 (Japan); Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046 (Japan)

2010-06-23T23:59:59.000Z

220

Laser-assisted sol-gel growth and characteristics of ZnO thin films  

SciTech Connect

ZnO thin films were grown on Si(100) substrates by a sol-gel method assisted by laser beam irradiation with a 325 nm He-Cd laser. In contrast to conventional sol-gel ZnO thin films, the surface morphology of the laser-assisted sol-gel thin films was much smoother, and the residual stress in the films was relaxed by laser irradiation. The luminescent properties of the films were also enhanced by laser irradiation, especially, by irradiation during the deposition and post-heat treatment stages. The incident laser beam is thought to play several roles, such as annihilating defects by accelerating crystallization during heat treatment, enhancing the surface migration of atoms and molecules, and relaxing the ZnO matrix structure during crystallization.

Kim, Min Su; Kim, Soaram [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae 621-749 (Korea, Republic of); Leem, Jae-Young [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Gimhae 621-749 (Korea, Republic of); Department of Nano Engineering, Inje University, Gimhae 621-749 (Korea, Republic of)

2012-06-18T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Improved electrical transport properties in p-type ZnO film by Rapid Dark thermal annealing process  

SciTech Connect

A rapid dark thermal annealing process at 800 deg. C of radio frequency sputtered P doped ZnO thin films have resulted in improved electrical transport properties with hole concentration of 1 x 1018 cm-3, mobility 4.37 cm2/Vs and resistivity 1.4 {Omega}-cm. X-ray photoelectron spectroscopy shows the presence of inactivated P in as-grown ZnO films.

Ghosh, Tushar; Basak, Durga [Department of Solid State Physics, Indian Association for the Cultivation of science, Jadavpur, Kolkata-700032 (India)

2012-06-05T23:59:59.000Z

222

Chloroform cometabolism by butane-grown CF8, Pseudomonas butanovora, and Mycobacterium vaccae JOB5 and methane-grown Methylosinus trichosporium  

E-Print Network (OSTI)

Chloroform cometabolism by butane-grown CF8, Pseudomonas butanovora, and Mycobacterium vaccae JOB5 AND ENVIRONMENTAL MICROBIOLOGY 63 (9): 3607-3613 SEP 1997 Abstract: Chloroform (CF) degradation by a butane-grown enrichment culture, CF8, was compared to that by butane-grown Pseudomonas butanovora and Mycobacterium vaccae

Semprini, Lewis

223

Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis  

SciTech Connect

The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

Nelson, Andrew T. [Los Alamos National Laboratory

2012-08-30T23:59:59.000Z

224

Room-temperature diluted magnetic semiconductors p-(Ga,Ni)N  

SciTech Connect

High concentration (5 at. %) Ni was incorporated into a chemical vapor deposition-grown GaN film by using a thin protecting Ni layer on top of the GaN film during ion implantation. After etching off the protecting layer, subsequent annealing up to 800 deg. C under flowing N{sub 2} resulted in a p-type GaN with apparent ferromagnetic behavior up to {approx}320 K. In addition, the ferromagnetic behavior became more manifest with increasing annealing temperature that increases hole concentration. No presence of any other second phases nor clusters in the Ni-implanted region was identifiable, at least to the 0.2 nm point-to-point resolution of high resolution transmission electron microscopy. This novel indirect implantation process that being easy to implement appears promising for attaining room-temperature diluted magnetic semiconductors which are applicable to magnetotransport, magneto-optical and spintronics devices, among others.

Huang, R.-T.; Hsu, C.-F.; Kai, J.-J.; Chen, F.-R.; Chin, T.-S. [Department of Engineering and System Science, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan (China)

2005-11-14T23:59:59.000Z

225

Are Films Ferroelectric?  

NLE Websites -- All DOE Office Websites (Extended Search)

as one unit cell. In these thin films, the ferroelectric phase forms in nanometerscale stripes of alternating polarity, which produce characteristic signals, satellite peaks, in...

226

ThinFilms  

NLE Websites -- All DOE Office Websites (Extended Search)

Thin Films Thin Films Manufacturing Technologies The Thin Film laboratory provides a variety of vapor deposition processes and facilities for cooperative research and development. Available capabilities include electron beam evaporation, sputter deposition, reactive deposi- tion processes, atomic layer deposition (ALD) and specialized techniques such as focused ion beam induced chemical vapor deposition. Equipment can be reconfigured for prototyping, or it can be dedicated to long-term research, development and manufacturing. Most sputter and evaporative deposition systems are capable of depositing multiple materials. Deposition capabilities and expertise * Deposition of a large variety of thin film mate- rials * Multiple sputter deposition systems - Capable of depositing four materials in a

227

Superhydrophobic Thin Film Coatings  

Exploiting its expertise with thin films and superhydrophobic materials, ORNL has developed a simple, inexpensive way to apply and reliably bond ...

228

Applications of Sputtered Films  

Science Conference Proceedings (OSTI)

...circuits Thin-film lasers Memory devices High-temperature superconductors A variety of sputtering techniques can be used in most applications,

229

Growth mechanisms and characterization of hydrogenated amorphous- silicon-alloy films. Annual subcontract report, 14 February 1991--13 February 1992  

SciTech Connect

This report describes an apparatus, constructed and tested, that allows measurement of the surface morphology of as-grown hydrogenated amorphous silicon films with atomic resolution using a scanning tunneling microscope. Surface topologies of 100-{degree}{Lambda}-thick intrinsic films, deposited on atomically flat, crystalline Si and GaAs, are reported. These films surfaces are relatively flat on the atomic scale, indicating fairly homogeneous, compact initial film growth. The effect of probe-tip size on the observed topology and the development of atomically sharp probes is discussed. 17 refs, 9 figs.

Gallagher, A.; Ostrom, R.: Stutzin, G.; Tanenbaum, D. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1993-02-01T23:59:59.000Z

230

The Diagnostic Process All plants grown indoors in containers  

E-Print Network (OSTI)

existing light. Bulbs of different light Caring for Plants in the Home Lynn Ellen Doxon, former Extension temperatures more closely resemble the tropics than local outdoor temperatures. Light Needs Even among plants that naturally grow in the shade, light needs vary. There are four basic light categories for indoor plants grown

Castillo, Steven P.

231

Microstructure of Ice Accretions Grown on Aluminum Conductors  

Science Conference Proceedings (OSTI)

In order to study the microstructure of glaze and rime deposits formed on the conductors of power lines, ice accretions are grown on a slowly rotating aluminum cylinder placed in the working section of a wind tunnel. The growth conditions cover ...

Jean-Louis Laforte; Luan C. Phan; Béatrice Felin

1983-07-01T23:59:59.000Z

232

Enhanced Semiconductor Nanocrystal Conductance via Solution Grown Contacts  

E-Print Network (OSTI)

in films of colloidal CdSe nanocrystals. Phys. Rev. B 2002,Nanojunctions in Gold CdSe Nanodumbbells. Phys. Rev. Lett.above displaying Au-tipped CdSe nanorods (left) and control

Sheldon, Matthew T.

2010-01-01T23:59:59.000Z

233

Flexible indium zinc oxide/Ag/indium zinc oxide multilayer electrode grown on polyethersulfone substrate by cost-efficient roll-to-roll sputtering for flexible organic photovoltaics  

Science Conference Proceedings (OSTI)

The authors describe the preparation and characteristics of flexible indium zinc oxide (IZO)-Ag-IZO multilayer electrodes grown on flexible polyethersulfone (PES) substrates using a roll-to-roll sputtering system for use in flexible organic photovoltaics. By the continuous roll-to-roll sputtering of the bottom IZO, Ag, and top IZO layers at room temperature, they were able to fabricate a high quality IZO-Ag-IZO multilayer electrode with a sheet resistance of 6.15 {epsilon}/square, optical transmittance of 87.4%, and figure of merit value of 42.03x10{sup -3} {Omega}{sup -1} on the PES substrate. In addition, the IZO-Ag-IZO multilayer electrode exhibited superior flexibility to the roll-to-roll sputter grown single ITO electrode due to the existence of a ductile Ag layer between the IZO layers and stable amorphous structure of the IZO film. Furthermore, the flexible organic solar cells (OSCs) fabricated on the roll-to-roll sputter grown IZO-Ag-IZO electrode showed higher power efficiency (3.51%) than the OSCs fabricated on the roll-to-roll sputter grown single ITO electrode (2.67%).

Park, Yong-Seok; Kim, Han-Ki [Department of Display Materials Engineering, Kyung Hee University, 1 Seochoen-dong, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2010-01-15T23:59:59.000Z

234

Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition (Remote PECVD)  

DOE Green Energy (OSTI)

We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of [mu]c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si,C:H and [mu]c-Si,C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si,C:H, [mu]c-Si and [mu]c-Si,C films. We studied the properties of doped a-Si:H and [mu]c-Si in MOS capacitors using [approximately]10 [Omega]-cm p-type crystalline substrates and thermally grown Si0[sub 2] dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si,O:H and doped a-Si:H films.

Lucovsky, G.; Nemanich, R.J.; Bernholc, J.; Whitten, J.; Wang, C.; Davidson, B.; Williams, M.; Lee, D.; Bjorkman, C.; Jing, Z. (North Carolina State Univ., Raleigh, NC (United States))

1993-01-01T23:59:59.000Z

235

Dissolution and electrochemical impedance spectroscopy studies of thin copper oxide films on copper in semi-aqueous fluoride solutions  

Science Conference Proceedings (OSTI)

The selective dissolution of thin copper oxide films grown on copper in semi-aqueous formulations containing dimethyl sulfoxide (DMSO), ammonium fluoride (NH"4F) and water was studied. Optimization of the formulations was carried out by systematic evaluation ... Keywords: BEOL cleaning, Copper oxide removal, Electrochemical impedance spectroscopy, SAF chemical system

N. Venkataraman; S. Raghavan

2010-11-01T23:59:59.000Z

236

Modeling and optimization of the growth rate for ZnO thin films using neural networks and genetic algorithms  

Science Conference Proceedings (OSTI)

The process modeling for the growth rate in pulsed laser deposition (PLD)-grown ZnO thin films was investigated using neural networks (NNets) based on the back-propagation (BP) algorithm and the process recipes was optimized via genetic algorithms (GAs). ... Keywords: Genetic algorithms, Neural networks, PLD, Process modeling, ZnO

Young-Don Ko; Pyung Moon; Chang Eun Kim; Moon-Ho Ham; Jae-Min Myoung; Ilgu Yun

2009-03-01T23:59:59.000Z

237

Epitaxial Thin Film Silicon Solar Cells Fabricated by Hot Wire Chemical Vapor Deposition Below 750 ..deg..C: Preprint  

SciTech Connect

We report on fabricating film c-Si solar cells on Si wafer templates by hot-wire chemical vapor deposition. These devices, grown at glass-compatible temperatures < 750..deg..C, demonstrate open-circuit voltages > 500 mV and efficiencies > 5%.

Alberi, K.; Martin, I. T.; Shub, M.; Teplin, C. W.; Iwaniczko, E.; Xu, Y.; duda, A.; Stradin, P.; Johnston, S. W.; Romero, M. J.; Branz, H. M.; Young, D. L.

2009-06-01T23:59:59.000Z

238

Adsorption of iso-/n-butane on an Anatase Thin Film: A Molecular Beam Scattering and TDS Study  

SciTech Connect

Binding energies and adsorption probabilities have been determined for n/iso-butane adsorption on an anatase thin film grown on SrTiO3(001) by means of thermal desorption spectroscopy (TDS) and molecular beam scattering. The sample has been characterized by x-ray diffraction (XRD) and Auger electrons spectroscopy (AES).

Goering, J.; Kadossov, E.; Burghaus, Uwe; Yu, Zhongqing; Thevuthasan, Suntharampillai; Saraf, Laxmikant V.

2007-07-01T23:59:59.000Z

239

Deposition of hetero-epitaxial In{sub 2}O{sub 3} thin films by molecular beam epitaxy  

SciTech Connect

Highly oriented thin film In{sub 2}O{sub 3} was heteroepitaxially grown on optically polished (100) plane of single crystalline yttria stabilized zirconia (YSZ) substrate using Molecular Beam Epitaxy (MBE). Full-width at half-maximum (FWHM) of X-ray rocking-curve showed 0.08{degree} for In{sub 2}O{sub 3} 200 nm thick layers indicating that excellent uniformity orientation compared with the heteroepitaxially-grown In{sub 2}O{sub 3} epitaxially deposited by the conventional methods such as electron-beam (e-beam) evaporation or sputtering method. The minimum yield ({chi}{sub min}) of the MBE grown in In{sub 2}O{sub 3} film of Rutherford Backscattering Spectrometry (RBS) was also extremely small value 3.1%, implying the very high crystallinity.

Taga, N.; Maekawa, M. [Asahi Glass Co., Ltd., Yokohama (Japan). Research Center; Shigesato, Y.; Yasui, I. [Univ. of Tokyo (Japan). Inst. of Industrial Science; Haynes, T.E. [Oak Ridge National Lab., TN (United States). Solid State Div.

1996-05-01T23:59:59.000Z

240

Growth and structure of epitaxial Pb{sub 1-x}Mn{sub x}Se(Ga) films  

Science Conference Proceedings (OSTI)

The growth and structure of Pb{sub 1-x}Mn{sub x}Se (Ga) (N{sub Ga} = 0.8 at %) films with thicknesses of 0.3-0.5 {mu}m, grown on single-crystal PbSe{sub 1-x}S{sub x} (100) substrates by molecular-beam epitaxy, have been studied. It is established that films grow in a face-centered cubic lattice with the (100) orientation, reproducing the substrate orientation. The optimal conditions for obtaining photosensitive epitaxial films with perfect crystal structure are determined (W{sub 1/2} = 70-80'').

Nuriyev, I. R., E-mail: mhagiyev@yahoo.com; Gadzhiyev, M. B.; Sadigov, R. M. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

2009-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Nanostructure of Fluorocarbon Films Deposited on Polystyrene from Hyperthermal C3F5 + Ions  

E-Print Network (OSTI)

Fluorocarbon films were grown on polystyrene in vacuum from 25- to 100-eV mass-selected C3F5 + ion beams. The films were analyzed by X-ray photoelectron spectroscopy, atomic force microscopy, and X-ray reflectivity after exposure to the atmosphere for 4-8 weeks. The X-ray reflectivity indicates films that range from ?30 to 60-Å thick. The thinner films form at lower ion energies, where the ion penetration depth and efficiency of film formation are lowest. X-ray reflectivity estimates air-fluorocarbon film roughness values of ?6 Å for 25- and 50-eV films but ?20 Å for the 100-eV films. The fluorocarbon-polystyrene-buried interface displays similar roughness and trends with ion energy. The AFM roughness trends are similar, but the absolute AFM roughnesses are only ? 1 /4 of the X-ray reflectivity values. This discrepancy is attributed to tip effects and the method of determining roughness by AFM. The AFM images and power spectral densities of the 100-eV films displayed quasi-periodic cones spaced 300-700 Å apart. Such features are either absent or of much lower amplitude in the 25- and 50-eV films. Classical molecular dynamics simulations of C3F5 + deposition on polystyrene at energies of 50 and 100 eV/ion reveal that etching at the higher energy is largely responsible for the dissimilar film structures obtained experimentally. These results demonstrate that deposition of the fluorocarbon polyatomic ion C3F5 + allows control of film nanostructure at the surface and buried interface. I.

F. Ahu Akin; Inkook Jang; Mark L. Schlossman; Susan B. Sinnott; Gerry Zajac; Erick R. Fuoco; Muthu B. J. Wijesundara; O Ming Li; Aleksey Tikhonov; Sai Venkatesh Pingali; A T. Wroble; Luke Hanley

2003-01-01T23:59:59.000Z

242

Thick film hydrogen sensor  

DOE Green Energy (OSTI)

A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

Hoffheins, Barbara S. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1995-01-01T23:59:59.000Z

243

Stabilized chromium oxide film  

DOE Patents (OSTI)

Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

Garwin, Edward L. (Los Altos, CA); Nyaiesh, Ali R. (Palo Alto, CA)

1988-01-01T23:59:59.000Z

244

Stabilized chromium oxide film  

DOE Patents (OSTI)

Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

Nyaiesh, A.R.; Garwin, E.L.

1986-08-04T23:59:59.000Z

245

Thin-film forces in pseudoemulsion films  

SciTech Connect

Use of foam for enhanced oil recovery (EOR) has shown recent success in steam-flooding field applications. Foam can also provide an effective barrier against gas coning in thin oil zones. Both of these applications stem from the unique mobility-control properties a stable foam possesses when it exists in porous media. Unfortunately, oil has a major destabilizing effect on foam. Therefore, it is important for EOR applications to understand how oil destroys foam. Studies all indicate that stabilization of the pseudoemulsion film is critical to maintain foam stability in the presence of oil. Hence, to aid in design of surfactant formulations for foam insensitivity to oil the authors pursue direct measurement of the thin-film or disjoining forces that stabilize pseudoemulsion films. Experimental procedures and preliminary results are described.

Bergeron, V.; Radke, C.J. [California Univ., Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley Lab., CA (United States)

1991-06-01T23:59:59.000Z

246

Nitrogen-incorporation induced changes in the microstructure of nanocrystalline WO3 thin films  

SciTech Connect

Nitrogen doped tungsten oxide (WO3) films were grown by reactive magnetron sputter-deposition by varying the nitrogen content in the reactive gas mixture keeping the deposition temperature fixed at 400 C. The crystal structure, surface morphology, chemical composition, and electrical resistivity of nitrogen doped WO3 films were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrical conductivity measurements. The results indicate that the nitrogen-doping induced changes in the microstructure and electrical properties of WO3 films are significant. XRD measurements coupled with SEM analysis indicates that the increasing nitrogen content decreases the grain size and crystal quality. The nitrogen concentration increases from 0 at.% to 1.35 at.% with increasing nitrogen flow rate from 0 to 20 sccm. The corresponding dc electrical conductivity of the films had shown a decreasing trend with increasing nitrogen content.

Vemuri, Venkata Rama Sesha R.; Noor-A-Alam, M.; Gullapalli, Satya K.; Engelhard, Mark H.; Ramana, C.V.

2011-12-30T23:59:59.000Z

247

Realization of low resistive p-ZnO thin film by Al-As codoping  

Science Conference Proceedings (OSTI)

Al-As codoping into ZnO has been proposed to realize low resistive and stable p-ZnO thin film by RF magnetron sputtering. Al-As codoping has been achieved by As back diffusion from GaAs substrate and sputtering Al doped ZnO target. Hall measurements showed that the hole concentration increases with the increase of Al concentration from 10{sup 15} to 10{sup 20} cm{sup -3}. Among the grown films, 1 at% Al doped ZnO: As showed low resistivity (3.5x10{sup -2}{Omega}cm) with high hole concentration. X-ray diffraction shows that all the films are crystallized in wurtzite structure with (002) preferential orientation. The diffusion of As atoms from the substrate and the presence of dopants in the film have been confirmed by Rutherford ford back scattering and energy dispersive spectroscopy analysis, respectively.

Balakrishnan, L.; Gowrishankar, S.; Gopalakrishnan, N. [Thin Film Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli 620015 (India)

2012-06-05T23:59:59.000Z

248

Strong room-temperature ferromagnetism of high-quality lightly Mn-doped ZnO grown by molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO grown by molecular beam epitaxy. With a low Mn concentration of 2 Multiplication-Sign 10{sup 19} cm{sup -3}, Mn-doped ZnO films exhibited room-temperature ferromagnetism with a coercivity field larger than 200 Oe, a large saturation moment of 6 {mu}{sub B}/ion, and a large residue moment that is {approx}70% of the saturation magnetization. Isolated ions with long range carrier mediated spin-spin coupling may be responsible for the intrinsic ferromagnetism.

Zuo Zheng; Zhou Huimei; Olmedo, Mario J.; Kong Jieying; Liu Jianlin [Quantum Structures Laboratory, Department of Electrical Engineering, University of California - Riverside, Riverside, California 92521 (United States); Beyermann, Ward P. [Department of Physics and Astronomy, University of California - Riverside, Riverside, California 92521 (United States); Zheng Jianguo [Laboratory for Electron and X-ray Instrumentation, California Institute for Telecommunications and Information Technology, University of California - Irvine, Irvine, California 92697 (United States); Xin Yan [NHMFL, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, Florida 32310-3706 (United States)

2012-09-01T23:59:59.000Z

249

Epitaxial EuO thin films on GaAs  

SciTech Connect

We demonstrate the epitaxial growth of EuO on GaAs by reactive molecular beam epitaxy. Thin films are grown in an adsorption-controlled regime with the aid of an MgO diffusion barrier. Despite the large lattice mismatch, it is shown that EuO grows well on MgO(001) with excellent magnetic properties. Epitaxy on GaAs is cube-on-cube and longitudinal magneto-optic Kerr effect measurements demonstrate a large Kerr rotation of 0.57 deg., a significant remanent magnetization, and a Curie temperature of 69 K.

Swartz, A. G.; Ciraldo, J.; Wong, J. J. I.; Li Yan; Han Wei; Lin Tao; Shi, J.; Kawakami, R. K. [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Mack, S.; Awschalom, D. D. [Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106 (United States)

2010-09-13T23:59:59.000Z

250

Scanning tunneling microscopy studies of the surfaces of a-Si:H and a-SiGe:H films  

SciTech Connect

The report contains a detailed description of the experimental complexities encountered in developing scanning tunneling microscope (STM) probing of atomic structure on the surface of freshly-grown hydrogenated-amorphous semiconductors. It also contains a speculative microscopic film-growth model that explains differences between the disorder in CVD grown a-Ge:H versus a-Si:H films. This model is derived from prior results obtained in the chemical analysis of GeH{sub 4} plasmas, combined with surface reaction and thermodynamic considerations. The neutral radical fragments of silane, disilane and germane dissociation in discharges, which dominate the vapor and film-growth reactions, have been deduced from detailed analysis of prior data and are reported. 4 refs., 7 figs.

Gallagher, A.; Ostrom, R.; Tannenbaum, D. (National Inst. of Standards and Technology, Boulder, CO (USA))

1991-06-01T23:59:59.000Z

251

Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates  

DOE Patents (OSTI)

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoconduit material coupled to a surface of the substrate. The substrate defines an aperture and the nanoconduit material defines a nanoconduit that is i) contiguous with the aperture and ii) aligned substantially non-parallel to a plane defined by the surface of the substrate.

Melechko, Anatoli V. (Oak Ridge, TN); McKnight, Timothy E. (Greenback, TN); Guillorn, Michael A. (Ithaca, NY); Ilic, Bojan (Ithaca, NY); Merkulov, Vladimir I. (Knoxville, TX); Doktycz, Mitchel J. (Knoxville, TN); Lowndes, Douglas H. (Knoxville, TN); Simpson, Michael L. (Knoxville, TN)

2012-03-27T23:59:59.000Z

252

Evolution of temperature dependent properties of oriented YBaCo{sub 4}O{sub 7} thin films  

SciTech Connect

Bulk YBaCo{sub 4}O{sub 7} was synthesized using a ceramic route in air. Thin films of this compound were grown on (100) oriented LaAlO{sub 3} substrate using a Pulsed Laser Deposition technique. X-ray diffraction results of thin film indicate that the film has (110) orientation. Electrical resistivity measurements, in 300K to 100K temperature range showed that the film is insulating, similar to that of the bulk. Spectroscopic ellipsometric measurements on thin films in the energy range 1.5 to 5 eV and at temperatures from 300 K to 400 K showed that the direct band gap s 2.45 eV at ambient temperature while its value increases with increase in temperature. The increase in band gap with temperature is attributed to the Moss-Burstein effect.

Nithya, R.; Sundari, S. Tripura; Kumary, T. Geetha; Chandra, Sharat; Mani, Awadhesh; Dash, S.; Sastry, V. Sankara [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102, TN (India)

2012-06-05T23:59:59.000Z

253

Thin film hydrogen sensor  

DOE Patents (OSTI)

A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

Cheng, Yang-Tse (Rochester Hills, MI); Poli, Andrea A. (Livonia, MI); Meltser, Mark Alexander (Pittsford, NY)

1999-01-01T23:59:59.000Z

254

Growth Diagram and Magnetic Properties of Hexagonal LuFe2O4 Thin Films  

Science Conference Proceedings (OSTI)

A growth diagram of Lu-Fe-O compounds on an MgO (111) substrate using pulsed laser deposition is constructed according to the experimental data. The LuFe2O4 phase can only be grown in a small range of temperature and O2 pressure conditions. Fundamental understanding of the growth mechanism of Lu-Fe-O compound films are gained in terms of the thermal chemistry at the surface. Superparamagnetism is observed in a film of LuFe2O4 clusters separated by the hexagonal LuFeO3 phase and structural defects.

Wang, Wenbin [ORNL; Gai, Zheng [ORNL; Chi, Miaofang [ORNL; Fowlkes, Jason Davidson [ORNL; Yi, Jieyu [ORNL; Zhu, Leyi [Argonne National Laboratory (ANL); Cheng, Xuemei [Bryn Mawr College; Keavney, David [Argonne National Laboratory (ANL); Snijders, Paul C [ORNL; Ward, Thomas Z [ORNL; Shen, Jian [ORNL; Xu, Xiaoshan [ORNL

2012-01-01T23:59:59.000Z

255

Group I-III-VI.sub.2 semiconductor films for solar cell application  

SciTech Connect

This invention relates to an improved thin film solar cell with excellent electrical and mechanical integrity. The device comprises a substrate, a Group I-III-VI.sub.2 semiconductor absorber layer and a transparent window layer. The mechanical bond between the substrate and the Group I-III-VI.sub.2 semiconductor layer is enhanced by an intermediate layer between the substrate and the Group I-III-VI.sub.2 semiconductor film being grown. The intermediate layer contains tellurium or substitutes therefor, such as Se, Sn, or Pb. The intermediate layer improves the morphology and electrical characteristics of the Group I-III-VI.sub.2 semiconductor layer.

Basol, Bulent M. (Redondo Beach, CA); Kapur, Vijay K. (Northridge, CA)

1991-01-01T23:59:59.000Z

256

Relaxation of photoinduced spins and carriers in ferromagnetic InMnSb films  

SciTech Connect

The authors report time resolved measurements and control of photoinduced spin and carrier relaxations in InMnSb ferromagnetic films with 2% Mn content (grown by low-temperature molecular beam epitaxy) using femtosecond laser pulses, and compare them to analogous measurements on InBeSb and InSb films. In this work, magneto-optical Kerr effect and standard pump-probe techniques provided a direct measure of the photoexcited spin and carrier lifetimes, respectively. They observe decrease in relaxations times in the high laser fluence regime and an absence of temperature dependence of the relaxation times.

Nontapot, K.; Kini, R. N.; Gifford, A.; Merritt, T. R.; Khodaparast, G. A.; Wojtowicz, T.; Liu, X.; Furdyna, J. K. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2007-04-02T23:59:59.000Z

257

Proposed Route to Thin Film Crystal Si Using Biaxially Textured Foreign Template Layers  

DOE Green Energy (OSTI)

We have developed a new approach to growing photovoltaic-quality crystal silicon (c-Si) films on glass. Other approaches to film c-Si focus on increasing grain size in order to reduce the deleterious effects of grain boundaries. Instead, we have developed an approach to align the silicon grains biaxially (both in and out of plane) so that 1) grain boundaries are "low-angle" and have less effect on the electronic properties of the material and 2) subsequent epitaxial thickening is simplified. They key to our approach is the use of a foreign template layer that can be grown with biaxial texture directly on glass.

Teplin, C. W.; Ginley, D. S.; van Hest, M.F.A.M.; Perkins, J. D.; Young, D. L.; Stradins, P.; Wang, Q.; Al-Jassim, M.; Iwaniczko, E.; Leenheer, A.; Jones, K. M.; Branz, H. M.

2005-11-01T23:59:59.000Z

258

Characterization of Ultrathin Films of -Al2O3 and the Chemistry of 1,3-Butadiene on NiAl(001) and -Al2O3  

E-Print Network (OSTI)

Characterization of Ultrathin Films of -Al2O3 and the Chemistry of 1,3-Butadiene on NiAl(001) and -Al2O3 Michelle M. Ivey, Kathryn A. Layman, Armen Avoyan, Heather C. Allen, and John C. HemmingerVine, California 92697 ReceiVed: October 3, 2002; In Final Form: March 27, 2003 Ultrathin films of -Al2O3 grown

259

TAMPERPROOF FILM BADGE  

DOE Patents (OSTI)

A persornel dosimeter film badge made of plastic, with provision for a picture of the wearer and an internal slide containing photographic film that is sensitive to various radiations, is described. Four windows made of differing material selectively attenuate alpha, beta, gamma rays, and neutrons so as to distinguish the particular type of radiation the wearer was subjected to. In addition, a lead shield has the identification number of the wearer perforated thereon so as to identify the film after processing. An internal magnetically actuated latch securely locks the slide within the body, and may be withdrawn only upon the external application of two strong magnetic forces in order to insure that the wearer or other curious persons will not accidentally expose the film to visual light.

Kocher, L.F.

1958-10-01T23:59:59.000Z

260

Thin film tritium dosimetry  

DOE Patents (OSTI)

The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

Moran, Paul R. (Madison, WI)

1976-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Ga-doped ZnO grown by pulsed laser deposition in H2: the roles of Ga and H  

DOE Green Energy (OSTI)

Highly conductive thin films of ZnO doped with Ga were grown by pulsed-laser deposition (PLD) with 10 mTorr of H2 in the growth chamber. Compared with a more conventional method of producing conductive films of ZnO, i.e., growth in O2 followed by annealing in forming gas (5% H2 in Ar), the H2 method requires no post-growth anneal and also produces higher carrier concentrations and lower resistivities with better depth uniformity. As an example, a 65-nm-thick sample had a room-temperature mobility of 32 cm2/V-s, a concentration of 6.8 x 1020 cm-3, and a resistivity of 2.9 x 10^-4 ohm-cm. From a scattering model, the donor and acceptor concentrations were calculated as 8.9 x 1020 and 2.1 x 10^20 cm-3, respectively, as compared to the Ga and H concentrations of 11 x 10^20 and 1 x 10^20 cm-3. Thus, H does not play a significant role as a donor in this type of ZnO

Look, David; Droubay, Timothy; McCloy, John S.; Zhu, Zihua; Chambers, Scott A.

2011-01-11T23:59:59.000Z

262

Microstructural evolution of thin film vanadium oxide prepared by pulsed-direct current magnetron sputtering  

Science Conference Proceedings (OSTI)

Vanadium oxide (VO{sub x}) thin films have been deposited by pulsed-DC magnetron sputtering using a metallic vanadium target in a reactive argon and oxygen environment. While the process parameters (power, total pressure, oxygen-to-argon ratio) remained constant, the deposition time was varied to produce films between 75 {+-} 6 and 2901 {+-} 30 A thick, which were then optically and electrically characterized. The complex dielectric function spectra ({epsilon} = {epsilon}{sub 1} + i{epsilon}{sub 2}) of the films from 0.75 to 5.15 eV were extracted by ex situ, multiple-angle spectroscopic ellipsometry (SE) measurements for the series of varied thickness VO{sub x} samples. Significant changes in {epsilon} and resistivity occur as a function of thickness, indicating the correlations exist between the electrical and the optical properties over this spectral range. In addition, in situ measurements via real time SE (RTSE) were made on the film grown to the largest thickness to track optical property and structural variations during growth. RTSE was also used to characterize changes in the film occurring after growth was completed, namely during post sputtering in the presence of argon and oxygen while the sample is shielded, and atmospheric exposure. RTSE indicates that the exposure of the film to the argon and oxygen environment, regardless of the shutter isolating the target, causes up to 200 A of the top surface of the deposited film to become more electrically resistive as evidenced by variations in {epsilon}. Exposure of the VO{sub x} thin film to atmospheric conditions introduces a similar change in {epsilon}, but this change occurs throughout the bulk of the film. A combination of these observations with RTSE results indicates that thinner, less ordered VO{sub x} films are more susceptible to drastic changes due to atmospheric exposure and that microstructural variations in this material ultimately control its environmental stability.

Motyka, M. A.; Horn, M. W. [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Gauntt, B. D. [Sandia National Laboratories, P.O. Box 5800-1411, Albuquerque, New Mexico 87185-1411 (United States); Dickey, E. C. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27606 (United States); Podraza, N. J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States)

2012-11-01T23:59:59.000Z

263

Thin Film Nanocomposites for Thermoelectric Applications  

Science Conference Proceedings (OSTI)

Presentation Title, Thin Film Nanocomposites for Thermoelectric Applications ... Abstract Scope, Thin film nanocomposites comprised of refractory metals and ...

264

Preferential orientation of Te precipitates in melt-grown CZT  

Science Conference Proceedings (OSTI)

Cadmium zinc telluride (Cd1-xZnxTe or CZT) has proved to be a useful material for semiconductor gamma-ray spectrometers and other electro-optic devices. It is often grown Te-rich to optimize its electrical characteristics, but this off-stoichiometric growth leads to the formation of semimetallic Te precipitates in the semiconducting host crystal. These precipitates can impair device performance and their formation needs to be inhibited, if possible, during growth. Characterization of melt-grown CZT has shown that Te precipitates are often faceted. In this study, characterization of several particles of different shapes revealed that most of the Te precipitates were preferentially oriented with the {101}CZT||{-12-10}Te . A secondary orientation relationship was also observed as {11-1}CZT||{01-11}Te for one of the {111}CZT family of planes. One of the particles exhibited {110}CZT||{01-10}Te and {001}CZT||{0001}Te . Precipitates were often found on {111}CZT twin boundaries and, in these cases, it was possible to assign specific orientations with respect to the twin plane. The expected orientation of the {0001}-plane of Te aligned with the {111}-plane of CZT was not observed even though a good lattice match is predicted in ab initio models. Observations of strained and polycrystalline Te precipitates are also discussed with relevance to the ab initio model and to impacts on electronic properties.

Henager, Charles H.; Edwards, Danny J.; Schemer-Kohrn, Alan L.; Bliss, Mary; Jaffe, John E.

2009-05-18T23:59:59.000Z

265

Light-trapped, interconnected, silicon-film {trademark} modules. Annual subcontract report, 18 November 1994--18 November 1995  

SciTech Connect

This report describes the first year of work performed by AstroPower, Inc., of Newark, Delaware, under the Thin-Film PV Partnership Program. The work led to the development of a new barrier-coated substrate that has enabled high-quality thin-layer polycrystalline silicon to be grown on a low-cost substrate. High diffusion lengths were measured after external phosphorous gettering. This led to a confirmed efficiency for a 0.57cm{sup 2}, thin-layer solar cell grown on a low-cost substrate.

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

1996-03-01T23:59:59.000Z

266

Ceramic Films Using Cathodic Electrodeposition  

Science Conference Proceedings (OSTI)

Electrodeposition is evolving as an important method in ceramic processing. Two processes for forming ceramic films by cathodic electrodeposition are ...

267

NMR characterization of thin films  

SciTech Connect

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

Gerald, II, Rex E. (Brookfield, IL); Klingler, Robert J. (Glenview, IL); Rathke, Jerome W. (Homer Glen, IL); Diaz, Rocio (Chicago, IL); Vukovic, Lela (Westchester, IL)

2008-11-25T23:59:59.000Z

268

Automated Electron Microscopy Film Scanner  

Renewable Energy; Environmental Technologies. ... film meets high performance specifications at higher electron energies while digital cameras do not; ...

269

Homobuffer thickness effect on the background electron carrier concentration of epitaxial ZnO thin films  

Science Conference Proceedings (OSTI)

Epitaxial ZnO thin films were grown on r-plane sapphire substrates using plasma-assisted molecular-beam epitaxy. ZnO homobuffer layers grown at a lower temperature were introduced to improve the crystallinity of the top ZnO thin films. Thicker homobuffer layers lead to better crystallinity of the subsequent epitaxial ZnO thin films due to the strain relaxation effect. Residual background electron carrier concentration in these undoped ZnO thin films first decreases, then increases as the buffer layer thickness increases from {approx}1 to 30 nm, with a minimum electron concentration of {approx}1x10{sup 17} cm{sup -3} occurring in ZnO homobuffer of {approx}5 nm. These results demonstrate that the optimized ZnO homobuffer thickness to achieve both good ZnO crystallinity and low residual electron concentration is determined by the relative electron carrier concentration ratios and mobility ratios between the buffer and epi-ZnO layers.

Yang, Z.; Zhou, H. M.; Li, L.; Zhao, J. Z.; Liu, J. L. [Department of Electrical Engineering, Quantum Structures Laboratory, University of California, Riverside, California 92521 (United States); Chen, W. V.; Yu, P. K. L. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2010-09-15T23:59:59.000Z

270

Thin film photovoltaic device  

DOE Patents (OSTI)

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Catalano, A.W.; Bhushan, M.

1982-08-03T23:59:59.000Z

271

Thin film photovoltaic device  

DOE Patents (OSTI)

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

Catalano, Anthony W. (Wilmington, DE); Bhushan, Manjul (Wilmington, DE)

1982-01-01T23:59:59.000Z

272

High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition  

Science Conference Proceedings (OSTI)

Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200?C, have resistivities in the low to mid 10-4 Omega cm range with a transmittance better than 85percent in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.

Anders, Andre; Lim, Sunnie H.N.; Yu, Kin Man; Andersson, Joakim; Rosen, Johanna; McFarland, Mike; Brown, Jeff

2009-04-24T23:59:59.000Z

273

Carbon nanotubes grown on bulk materials and methods for fabrication  

DOE Patents (OSTI)

Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

Menchhofer, Paul A. (Clinton, TN); Montgomery, Frederick C. (Oak Ridge, TN); Baker, Frederick S. (Oak Ridge, TN)

2011-11-08T23:59:59.000Z

274

Conflicting Views of Homosexuality Among the Mainstream Films and Gay "Pink" Films of Japan.  

E-Print Network (OSTI)

??This thesis will examine the representation of homosexuality in Japanese films through analyzing gay "pink" films, which are soft-core porn films exhibited in specialized theaters,… (more)

Ogawa, Sho

2008-01-01T23:59:59.000Z

275

Thin film photovoltaic cell  

DOE Patents (OSTI)

A thin film photovoltaic cell having a transparent electrical contact and an opaque electrical contact with a pair of semiconductors therebetween includes utilizing one of the electrical contacts as a substrate and wherein the inner surface thereof is modified by microroughening while being macro-planar.

Meakin, John D. (Newark, DE); Bragagnolo, Julio (Newark, DE)

1982-01-01T23:59:59.000Z

276

Thin-film optical initiator  

DOE Patents (OSTI)

A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

Erickson, Kenneth L. (Albuquerque, NM)

2001-01-01T23:59:59.000Z

277

Pulsed ion beam methods for in situ characterization of diamond film deposition processes  

DOE Green Energy (OSTI)

Diamond and diamond-like carbon (DLC) have properties which in principle make them ideally suited to a wide variety of thin-film applications. Their widespread use as thin films, however, has been limited for a number of reasons related largely to the lack of understanding and control of the nucleation and growth processes. Real-time, in situ studies of the surface of the growing diamond film are experimentally difficult because these films are normally grown under a relatively high pressure of hydrogen, and conventional surface analytical methods require an ultrahigh vacuum environment. It is believed, however, that the presence of hydrogen during growth is necessary to stabilize the corrugated diamond surface structure and thereby prevent the formation of the graphitic phase. Pulsed ion beam-based analytical methods with differentially pumped ion sources and particle detectors are able to characterize the uppermost atomic layer of a film during, growth at ambient pressures 5-7 orders of magnitude higher than other surface-specific analytical methods. We describe here a system which has been developed for the purpose of determining the hydrogen concentration and bonding sites on diamond surfaces as a function of sample temperature and ambient hydrogen pressure under hot filament CVD growth conditions. It is demonstrated that as the hydrogen partial pressure increases, the saturation hydrogen coverage of the surface of a CVD diamond film increases, but that the saturation level depends on the atomic hydrogen concentration and substrate temperature.

Krauss, A.R.; Smentkowski, V.S.; Zuiker, C.D.; Gruen, D.M. [Argonne National Lab., IL (United States); Im, J. [Argonne National Lab., IL (United States)]|[Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Schultz, J.A.; Waters, K. [Ionwerks Corp., Houston, TX (United States); Chang, R.P.H. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering

1995-06-01T23:59:59.000Z

278

Transparent conductive indium zinc oxide films prepared by pulsed plasma deposition  

Science Conference Proceedings (OSTI)

Transparent conductive indium zinc oxide films were prepared by pulsed plasma deposition from a ceramic target (90 wt. % In{sub 2}O{sub 3} and 10 wt. % ZnO). The dependences of film properties upon the substrate temperature was investigated using characterization methods including x-ray diffraction, atomic force microscope, Hall measurement, ultraviolet-visible spectroscopy, and x-ray photoelectron spectroscopy. The films grown at room temperature had a rather smooth surface due to the amorphous structure, with a root mean square roughness of less than 1 nm. The atomic ratio of Zn/(Zn + In) in these films is 15.3 at. %, which is close to that in the target, and the chemical states of indium and zinc atoms were In{sup 3+} and Zn{sup 2+}, respectively. The films deposited on a substrate with a temperature of 200 Degree-Sign C exhibited polycrystalline structure and a preferred growth orientation along the (222) plane. Here the electrical properties were improved due to the better crystallinity, with the films exhibiting a minimum resistivity value of 4.2 Multiplication-Sign 10{sup -4}{Omega} cm, a maximum carrier mobility of 45 cm{sup 2} V{sup -1} s{sup -1}, and an optical transmittance over 80% in the visible region.

Wan Runlai; Yang Ming; Zhou Qianfei; Zhang Qun [Department of Materials Science, Fudan University, Shanghai 200433 (China)

2012-11-15T23:59:59.000Z

279

Origin of stress in radio frequency magnetron sputtered zinc oxide thin films  

SciTech Connect

Highly c-axis oriented ZnO thin films have been deposited on silicon substrates by planar rf magnetron sputtering under varying pressure (10-50 mTorr) and oxygen percentage (50-100%) in the reactive gas (Ar + O{sub 2}) mixture. The as-grown films were found to be stressed over a wide range from -1 x 10{sup 11} to -2 x 10{sup 8} dyne/cm{sup 2} that in turn depends strongly on the processing conditions, and the film becomes stress free at a unique combination of sputtering pressure and reactive gas composition. Raman spectroscopy and photoluminescence (PL) analyses identified the origin of stress as lattice distortion due to defects introduced in the ZnO thin film. FTIR study reveals that Zn-O bond becomes stronger with the increase in oxygen fraction in the reactive gas mixture. The lattice distortion or stress depends on the type of defects introduced during deposition. PL spectra show the formation of a shoulder in band emission with an increase in the processing pressure and are related to the presence of stress. The ratio of band emission to defect emission decreases with the increase in oxygen percentage from 50 to 100%. The studies show a correlation of stress with the structural, vibrational, and photoluminescence properties of the ZnO thin film. The systematic study of the stress will help in the fabrication of efficient devices based on ZnO film.

Menon, Rashmi; Gupta, Vinay; Sreenivas, K. [Electronic Material and Devices Laboratory, Department of Physics and Astrophysics, University of Delhi, Delhi 11007 (India); Tan, H. H.; Jagadish, C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)

2011-03-15T23:59:59.000Z

280

NFRC Procedures for Applied Films  

NLE Websites -- All DOE Office Websites (Extended Search)

Applied Films Applied Films Last update: 12/10/2013 07:29 PM NFRC now has a procedure for adding applied films to substrates in Optics5 and importing those applied film constructions into WINDOW5 to be used in a whole product calculation. The information presented below is provided to help simulators with this process. Feel free to contact us at WINDOWHelp@lbl.gov with questions or comments. NFRC Applied Film Procedure Applied Film Procedures (approved by NFRC) (PDF file) Approved Applied Film List (IGDB 33.0) (PDF file) NFRC Laminate Procedure Training Powerpoint with Examples (This Powerpoint presentation was used in the NFRC web based training sessions in December 2006 and January 2007) PowerPoint Presentation (PPT file) PowerPoint Presentation (PDF file) Help and Troubleshooting

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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281

Method for making carbon films  

DOE Patents (OSTI)

A method for treating an organic polymer material, preferably a vinylidene chloride/vinyl chloride copolymer (Saran) to produce a flat sheet of carbon film material having a high surface area ([approx equal]1000 m[sup 2] /g) suitable as an electrode material for super capacitor applications. The method comprises heating a vinylidene chloride/vinyl chloride copolymer film disposed between two spaced apart graphite or ceramic plates to a first temperature of about 160 C for about 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, thereafter heating the stabilized film to a second temperature of about 750 C in an inert atmosphere for about one hour to form a carbon film; and finally activating the carbon film to increase the surface area by heating the carbon film in an oxidizing atmosphere to a temperature of at least 750--850 C for between 1--6 hours. 2 figs.

Tan, M.X.

1999-07-29T23:59:59.000Z

282

Method for making carbon films  

DOE Patents (OSTI)

A method for treating an organic polymer material, preferably a vinylidene chloride/vinyl chloride copolymer (Saran) to produce a flat sheet of carbon film material having a high surface area (.apprxeq.1000 m.sup.2 /g) suitable as an electrode material for super capacitor applications. The method comprises heating a vinylidene chloride/vinyl chloride copolymer film disposed between two spaced apart graphite or ceramic plates to a first temperature of about 160.degree. C. for about 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, thereafter heating the stabilized film to a second temperature of about 750.degree. C. in an inert atmosphere for about one hour to form a carbon film; and finally activating the carbon film to increase the surface area by heating the carbon film in an oxidizing atmosphere to a temperature of at least 750-850.degree. C. for between 1-6 hours.

Tan, Ming X. (Livermore, CA)

1999-01-01T23:59:59.000Z

283

Thin film superconductor magnetic bearings  

DOE Patents (OSTI)

A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

Weinberger, Bernard R. (Avon, CT)

1995-12-26T23:59:59.000Z

284

Structure and features of the surface morphology of A{sup 4}B{sup 6} chalcogenide epitaxial films  

Science Conference Proceedings (OSTI)

The structure and features of the surface morphology of Pb{sub 1-x}Mn{sub x}Se (x = 0.03) epitaxial films grown on freshly cleaved BaF{sub 2}(111) faces and PbSe{sub 1-x}S{sub x}(100) (x = 0.12) single-crystal wafers were investigated by molecular beam condensation and the hot-wall method. It is shown that the epitaxial films, in accordance with the data in the literature for other chalcogenides, grow in the (111) and (100) planes, repeating the substrate orientation. Black aggregates are observed on the film surface of the films grown. The results obtained are compared with the data in the literature and generalized for other chalcogenides: A{sup 4}B{sup 6}:Pb (S, Se, Te); Pb{sub 1-x}Sn{sub x} (S, Se, Te); and Pb{sub 1-x}Mn (Se, Te). It is established that the formation of black aggregates, which are second-phase inclusions on the surface of epitaxial films obtained by vacuum thermal deposition, is characteristic of narrow-gap A{sup 4}B{sup 6} chalcogenides.

Nuriyev, I. R., E-mail: afinnazarov@yahoo.com [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan)

2009-12-15T23:59:59.000Z

285

Effect of in-situ oxygen on the electronic properties of graphene grown by carbon molecular beam epitaxy grown  

Science Conference Proceedings (OSTI)

We report that graphene grown by molecular beam epitaxy from solid carbon (CMBE) on (0001) SiC in the presence of unintentional oxygen exhibits a small bandgap on the order of tens of meV. The presence of bandgaps is confirmed by temperature dependent Hall effect and resistivity measurements. X-ray photoelectron spectroscopy (XPS) measurements suggest that oxygen incorporates into the SiC substrate in the form of O-Si-C and not into the graphene as graphene oxide or some other species. The effect is independent of the carrier type of the graphene. Temperature dependent transport measurements show the presence of hopping conduction in the resistivity and a concurrent disappearance of the Hall voltage. Interactions between the graphene layers and the oxidized substrate are believed to be responsible for the bandgap.

Park, Jeongho; Mitchel, W. C.; Back, Tyson C. [Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXPS), Wright-Patterson AFB, Ohio 45433-7707 (United States); Elhamri, Said [Department of Physics, University of Dayton, Dayton, Ohio 45469 (United States)

2012-03-26T23:59:59.000Z

286

HfO2 Gate Dielectric on (NH4)2S Passivated (100) GaAs Grown by Atomic Layer Deposition  

Science Conference Proceedings (OSTI)

The interface between hafnium oxide grown by atomic layer deposition and (100) GaAs treated with HCl cleaning and (NH{sub 4}){sub 2}S passivation has been characterized. Synchrotron radiation photoemission core level spectra indicated successful removal of the native oxides and formation of passivating sulfides on the GaAs surface. Layer-by-layer removal of the hafnia film revealed a small amount of As{sub 2}O{sub 3} formed at the interface during the dielectric deposition. Traces of arsenic and sulfur out-diffusion into the hafnia film were observed after a 450 C post-deposition anneal, and may be the origins for the electrically active defects. Transmission electron microscopy cross section images showed thicker HfO{sub 2} films for a given precursor exposure on S-treated GaAs versus the non-treated sample. In addition, the valence-band and the conduction-band offsets at the HfO{sub 2}/GaAs interface were deduced to be 3.18 eV and a range of 0.87-0.97 eV, respectively. It appears that HCl+(NH{sub 4})2{sub S} treatments provide a superior chemical passivation for GaAs and initial surface for ALD deposition.

Chen, P.T.; /Stanford U., Materials Sci. Dept.; Sun, Y.; /SLAC, SSRL; Kim, E.; McIntyre, P.C.; /Stanford U., Materials Sci. Dept.; Tsai, W.; Garner, M.; /Intel, Santa Clara; Pianetta, P.; /SLAC, SSRL; Nishi, Y.; /Stanford U., Elect. Eng. Dept.; Chui, C.O.; /UCLA

2007-09-28T23:59:59.000Z

287

Photoluminescence study of GaAs films on Si(100) grown by atomic hydrogen-assisted molecular beam epitaxy  

Science Conference Proceedings (OSTI)

Keywords: atomic hydrogen-mediated epitaxy, lattice-mismatched heteroepitaxy, minority carrier lifetime, molecular beam epitaxy, photoluminescence decay, solar cells

Yoshitaka Okada; Shigeru Ohta; Akio Kawabata; Hirofumi Shimomura; Mitsuo Kawabe

1994-03-01T23:59:59.000Z

288

Ellipsometry of anodic film growth  

DOE Green Energy (OSTI)

An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

Smith, C.G.

1978-08-01T23:59:59.000Z

289

Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition (Remote PECVD). Annual subcontract report, 1 September 1990--31 August 1991  

DOE Green Energy (OSTI)

We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of {mu}c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si,C:H and {mu}c-Si,C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si,C:H, {mu}c-Si and {mu}c-Si,C films. We studied the properties of doped a-Si:H and {mu}c-Si in MOS capacitors using {approximately}10 {Omega}-cm p-type crystalline substrates and thermally grown Si0{sub 2} dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si,O:H and doped a-Si:H films.

Lucovsky, G.; Nemanich, R.J.; Bernholc, J.; Whitten, J.; Wang, C.; Davidson, B.; Williams, M.; Lee, D.; Bjorkman, C.; Jing, Z. [North Carolina State Univ., Raleigh, NC (United States)

1993-01-01T23:59:59.000Z

290

934 / JOURNAL OF ENVIRONMENTAL ENGINEERING / OCTOBER 2000 CHLORINATED SOLVENT COMETABOLISM BY BUTANE-GROWN  

E-Print Network (OSTI)

BY BUTANE-GROWN MIXED CULTURE By Young Kim,1 Daniel J. Arp,2 and Lewis Semprini3 ABSTRACT: A survey of aerobic cometabolism of chlorinated aliphatic hydrocarbons by a butane-grown mixed culture was performed and was inhibited by butane and inactivated by acetylene, indicating that a monooxygenase enzyme was likely involved

Semprini, Lewis

291

Falling film evaporator  

DOE Patents (OSTI)

A falling film evaporator including a vertically oriented pipe heated exteriorly by a steam jacket and interiorly by a finned steam tube, all heating surfaces of the pipe and steam tube being formed of a material wet by water such as stainless steel, and packing within the pipe consisting of Raschig rings formed of a material that is not wet by water such as polyvinylidene fluoride.

Bruns, Lester E. (Kennewick, WA)

1976-01-01T23:59:59.000Z

292

Vertically Aligned Nanocomposite Thin Films  

E-Print Network (OSTI)

Vertically aligned nanocomposite (VAN) thin films have recently stimulated significant research interest to achieve better material functionality or multifunctionalities. In VAN thin films, both phases grow epitaxially in parallel on given substrates and form a unique nano-checkerboard structure. Multiple strains, including the vertical strain which along the vertical interface and the substrate induced strain which along the film and substrate interface, exist in VAN thin films. The competition of these strains gives a promise to tune the material lattice structure and future more the nanocomposite film physical properties. Those two phases in the VAN thin films are selected based on their growth kinetics, thermodynamic stability and epitaxial growth ability on given substrates. In the present work, we investigated unique epitaxial two-phase VAN (BiFeO3)x:(Sm2O3)1-x and (La0.7Sr0.3MnO3)x:(Mn3O4)1-x thin film systems by pulsed laser deposition. These VAN thin films exhibit a highly ordered vertical columnar structure with good epitaxial quality. The strain of the two phases can be tuned by deposition parameters, e.g. deposition frequency and film composition. Their strain tunability is found to be related directly to the systematic variation of the column widths and domain structures. Their physical properties, such as dielectric loss and ferromagnetisms can be tuned systematically by this variation. The growth morphology, microstructure and material functionalities of VAN thin films can be varied by modifying the phase ratio, substrate orientation or deposition conditions. Systematic study has been done on growing (SrTiO3)0.5:(MgO)0.5 VAN thin films on SrTiO3 and MgO substrates, respectively. The variation of column width demonstrates the substrate induced strain plays another important role in the VAN thin film growth. The VAN thin films also hold promise in achieving porous thin films with ordered nanopores by thermal treatment. We selected (BiFeO3)0.5:(Sm2O3)0.5 VAN thin films as a template and get uniformly distributed bi-layered nanopores. Controllable porosity can be achieved by adjusting the microstructure of VAN (BiFeO3):(Sm2O3) thin films and the annealing parameters. In situ heating experiments within a transmission electron microscope column provide direct observations into the phases transformation, evaporation and structure reconstruction during the annealing. Systematic study in this dissertation demonstrate that the vertically aligned nanocomposite microstructure is a brand new architecture in thin films and an exciting approach that promises tunable material functionalities as well as novel nanostructures.

Bi, Zhenxing

2011-05-01T23:59:59.000Z

293

Understanding the defect structure of solution grown zinc oxide  

Science Conference Proceedings (OSTI)

Zinc oxide (ZnO) is a wide bandgap semiconducting oxide with many potential applications in various optoelectronic devices such as light emitting diodes (LEDs) and field effect transistors (FETs). Much effort has been made to understand the ZnO structure and its defects. However, one major issue in determining whether it is Zn or O deficiency that provides ZnO its unique properties remains. X-ray absorption spectroscopy (XAS) is an ideal, atom specific characterization technique that is able to probe defect structure in many materials, including ZnO. In this paper, comparative studies of bulk and aqueous solution grown ({lighting and other optoelectronic device applications. - Graphical abstract: Highlights: Black-Right-Pointing-Pointer ZnO powders have been synthesized through an aqueous solution method. Black-Right-Pointing-Pointer Defect structure studied using XAS and XPDF. Black-Right-Pointing-Pointer Zn-Zn correlations are less in the ZnO powders synthesized in solution than bulk. Black-Right-Pointing-Pointer Zn vacancies are present in the powders synthesized. Black-Right-Pointing-Pointer EXAFS and XPDF, when used complementary, are useful characterization techniques.

Liew, Laura-Lynn [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Sankar, Gopinathan, E-mail: g.sankar@ucl.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Handoko, Albertus D. [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); Goh, Gregory K.L., E-mail: g-goh@imre.a-star.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Block N4.1 Nanyang Avenue, Singapore 639798 (Singapore); Kohara, Shinji [Japan Synchrotron Radiation Research Institute (JASRI), Mikazuki, Sayo, Hyogo 679-5198 (Japan)

2012-05-15T23:59:59.000Z

294

APIVT-Grown Silicon Thin Layers and PV Devices: Preprint  

DOE Green Energy (OSTI)

Large-grained (5-20 ..mu..m) polycrystalline silicon layers have been grown at intermediate temperatures of 750-950C directly on foreign substrates without a seeding layer by iodine vapor transport at atmospheric pressure with rates as high as 3 mm/min. A model is constructed to explain the atypical temperature dependence of growth rate. We have also used this technique to grow high-quality epitaxial layers on heavily doped CZ-Si and on upgraded MG-Si substrates. Possible solar cell structures of thin-layer polycrystalline silicon on foreign substrates with light trapping have been examined, compared, and optimized by two-dimensional device simulations. The effects of grain boundary re-combination on device performance are presented for two grain sizes of 2 and 20 mm. We found that 104 cm/s recombination velocity is adequate for 20-m m grain-sized thin silicon, whereas a very low recombination velocity of 103 cm/s must be accomplished in order to achieve reasonable performance for a 2- mm grain-sized polycrystalline silicon device.

Wang, T. H.; Ciszek, T. F.; Page, M. R.; Bauer, R. E.; Wang, Q.; Landry, M. D.

2002-05-01T23:59:59.000Z

295

Gradual localization of Ni 3d states in LaNiO3 ultrathin films induced by dimensional crossover  

Science Conference Proceedings (OSTI)

In situ photoemission spectroscopy and x-ray absorption spectroscopy (XAS) have been performed on LaNiO3 (LNO) ultrathin films grown on LaAlO3 substrates to investigate the origin of the thickness-dependent metalinsulator transition (MIT). With decreasing film thickness, the progressive weakening of a quasiparticle peak at the Fermi level (EF ) occurs below 10 monolayer (ML), and the further depletion of spectral weight at EF leads to pseudogap behavior at 3 6 ML. The pseudogap finally evolves into a full gap, indicating that the thickness-dependent MIT takes place at a critical film thickness of 2 3 ML. The observed spectral behavior is in line with the transport properties of LNO ultrathin films. The thickness dependence of the spectral intensity is compared with realistic multiorbital dynamical mean-field theory. The experimental spectral function was found to depend on the film thickness more strongly than the theoretical one for thinner systems, indicating that the thickness-dependent MIT in LNO is caused by the crossover from three to two dimensions, during which the spatial correlations are progressively enhanced. The XAS results suggest that a charge disproportionate state is strongly suppressed in LNO ultrathin films plausibly as a result of epitaxial strain from the substrates. These results strongly suggest that a novel insulating state is realized in LNO films at a thin limit.

Sakai, E. [University of Tokyo, Tokyo, Japan; Tamamitsu, M. [University of Tokyo, Tokyo, Japan; Yoshimatsu, K [University of Tokyo, Tokyo, Japan; Okamoto, Satoshi [ORNL; Horiba, K. [University of Tokyo, Tokyo, Japan; Oshima, M [University of Tokyo, Tokyo, Japan; Kumigashira, H [University of Tokyo, Tokyo, Japan

2013-01-01T23:59:59.000Z

296

Hall effect in superconducting films  

E-Print Network (OSTI)

Near the superconducting phase transition, fluctuations significantly modify the electronic transport properties. Here we study the fluctuation corrections to the Hall conductivity in disordered films, extending previous ...

Michaeli, Karen

297

Thin Films and Interfaces Committee  

Science Conference Proceedings (OSTI)

The Thin Films and Interfaces Committee is part of the Electronic, Magnetic, and Photonic Materials Division;. Our Mission: Promotes knowledge of the science ...

298

Simulated Space Environmental Testing on Thin Films  

Science Conference Proceedings (OSTI)

An exploratory program has been conducted, to irradiate some mature commercial and some experimental polymer films with radiation simulating certain Earth orbits, and to obtain data about the response of each test film''s reflective and tensile properties. ...

Russell Dennis A.; Fogdall Larry B.; Bohnhoff Gail

2000-04-01T23:59:59.000Z

299

Growth dynamics of pentacene thin films: Real-time synchrotron x-ray scattering study  

Science Conference Proceedings (OSTI)

Real-time synchrotron x-ray scattering in the anti-Bragg configuration was used to monitor the dynamics of pentacene film growth on inert substrates. A distributed-growth model, according to which pentacene molecules adsorbed on the nth layer can either nucleate and contribute to the growth of the (n+1)th layer or transfer downward and contribute to the growth of the nth layer, gave a good description of the data. For molecules adsorbed on the first and second layers, the probability of downward transfer was found to be dependent on the substrate, and independent of temperature within the range from 25 to 60 deg. C. For films grown on SiO{sub 2}, an Ehrlich-Schwoebel barrier of the order of 70 meV dominated downward transfer of pentacene molecules in layers away from the substrate. For films grown on an alkylated self-assembled monolayer, significant desorption of pentacene molecules from the substrate at elevated temperatures forced the growth mode toward the three-dimensional limit.

Mayer, Alex C.; Ruiz, Ricardo; Malliaras, George G. [Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Zhou, Hua; Headrick, Randall L. [Department of Physics, University of Vermont, Burlington, Vermont 05405 (United States); Kazimirov, Alexander [Cornell High Energy Synchrotron Source, Ithaca, New York 14853 (United States)

2006-05-15T23:59:59.000Z

300

Fine structure of AlN/AlGaN superlattice grown by pulsed atomic-layer epitaxy for dislocation filtering  

SciTech Connect

We report the detailed structure analysis of our AlN/AlGaN superlattice (SL) grown by pulsed atomic-layer epitaxy (PALE) for dislocation filtering. Due to the nature of PALE, the AlGaN well material itself in the SL was found to be composed actually of an Al{sub x}Ga{sub 1-x}N/Al{sub y}Ga{sub 1-y}N short-period superlattice (SPSL), with the periodicity of 15.5 A ({approx_equal}6 monolayer), determined consistently from high-resolution x-ray diffraction and high-resolution transmission electron microscopy measurements. The SPSL nature of the AlGaN layers is believed to benefit from the AlN/AlGaN SL's coherent growth, which is important in exerting compressive strain for the thick upper n-AlGaN film, which serves to eliminate cracks. Direct evidence is presented which indicates that this SL can dramatically reduce the screw-type threading dislocation density.

Sun, W.H.; Zhang, J.P.; Yang, J.W.; Maruska, H.P.; Khan, M. Asif; Liu, R.; Ponce, F.A. [Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States); Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85287 (United States)

2005-11-21T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Atomic-resolution study of polarity reversal in GaSb grown on Si by scanning transmission electron microscopy  

SciTech Connect

The atomic-resolved reversal of the polarity across an antiphase boundary (APB) was observed in GaSb films grown on Si by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The investigation of the interface structure at the origin of the APB reveals that coalescence of two domains with Ga-prelayer and Sb-prelayer causes the sublattice reversal. The local strain and lattice rotation distributions of the APB, attributed to the discordant bonding length at the APB with the surrounding GaSb lattice, were further studied using the geometric phase analysis technique. The crystallographic characteristics of the APBs and their interaction with other planar defects were observed with HAADF-STEM. The quantitative agreement between experimental and simulated images confirms the observed polarities in the acquired HAADF-STEM data. The self-annihilation mechanism of the APBs is addressed based on the rotation induced by anti-site bonds and APBs' faceting.

Hosseini Vajargah, S.; Woo, S. Y.; Botton, G. A. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Brockhouse Institute for Material Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Ghanad-Tavakoli, S. [Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Kleiman, R. N.; Preston, J. S. [Brockhouse Institute for Material Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)

2012-11-01T23:59:59.000Z

302

Formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy  

SciTech Connect

We report the phase formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy. We find the alloy with low- and high-Be contents could be obtained by alloying BeO into ZnO films. X-ray diffraction measurements shows the c lattice constant value shrinks, and room temperature absorption shows the energy band-gap widens after Be incorporated. However, the alloy with intermediate Be composition are unstable and segregated into low- and high-Be contents BeZnO alloys. We demonstrate the phase segregation of Be{sub x}Zn{sub 1-x}O alloys with intermediate Be composition resulted from large internal strain induced by large lattice mismatch between BeO and ZnO.

Chen, Mingming; Zhu, Yuan; Su, Longxing; Zhang, Quanlin; Chen, Anqi; Ji, Xu; Xiang, Rong; Gui, Xuchun; Wu, Tianzhun [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Pan, Bicai [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang, Zikang [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China) [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

2013-05-20T23:59:59.000Z

303

Thin film growth and characterization of Potassium-Tantalate-Niobate room temperature ferroelectric  

E-Print Network (OSTI)

The primary objective in fabricating ferroelectric thin films is to duplicate the polar properties and characteristics of the corresponding bulk material. Potassium Tantalate-Niobate (KTN), KTa(,-,)Nb,03-, is a continuous solid solution between the perovskite compounds KNbO3 and KTaO3. The Curie temperature of KTN can be varied by a4justing x i.e.., the composition of niobium. In the vicinity of the ferroto-paraelectric phase transition, high dielectric permittivities, large pyroelectric as well as electro-optical and nonlinear optical coefficients can be observed. Bulk KTN single crystals synthesized from high temperature melts have limited device utility due to the occurence of lamellar growth, twins, etc. For these reasons thin films of KTN find enormous applications in spatial light modulators., pyroelectric devices, holographic storage., parametric oscillators and variable delay lines. The research undertaken involved the growth of KTN thin films on lattice matched substrates. The preferential groath directions, optimum growth conditions, ideal charge composition, and ideal regime in phase diagram were established. Liquidphase epitaxy (LPE) was the technique employed for the growth of thin films. The as grown films were optically and electrically characterized.

Muntha, Nageswara Rao Venkat

1995-01-01T23:59:59.000Z

304

Epitaxial growth of metal fluoride thin films by pulsed-laser deposition  

SciTech Connect

We have studied growth of GdLiF4 thin films for optical waveguide applications. Epitaxial, c-axis oriented GdLiF4 films wer grown from undoped GdLiF4 targets in an on-axis Pulsed-laser deposition geometry on (100) CaF2. These films exhibit a high density of particulates on the surface which are ejected from the target in the ablation process. Growth from Nd-doped polycrystalline GdLiF4 ablation targets results in smooth films with lower particulate densities, as Nd doping increases the optical absorption of GdLiF4 at the ablation laser wavelength 193 nm and permits efficient pulsed-laser deposition. Optical emission spectra of the ablation pume reveals the presence of atomic F, Gd, and Li, indicating the dissociation of the metal-fluorine bonds in the ablation process. In addition, we find that the residual background oxygen pressure must be reduced to avoid formation of Gd4O3F6 as an impurity oxyfluoride phase in the films.

Norton, D.P.; Budal, J.D.; Chakoumakos, B.C.; Geohegan, D.B. [Oak Ridge National Lab., TN (United States); Puretzky, A. [AN SSSR, Troitsk (Russian Federation). Inst. Spektroskopii

1995-12-01T23:59:59.000Z

305

Transition between the 1 x 1 and ({radical}3 x 2{radical}3)R30{degree} surface structures of GaN in the vapor-phase environment  

SciTech Connect

Out-of-plane structures of the GaN(0001) surface in the metal-organic chemical vapor deposition (MOCVD) environment have been determined using in situ grazing-incidence X-ray scattering. The authors measured 11{bar 2}{ell} crystal truncation rod intensities at a variety of temperatures and ammonia partial pressures on both sides of the 1 x 1 to ({radical}3 x 2{radical}3)R30{degree} surface phase transition. The out-of-plane structure of the ({radical}3 x 2{radical}3)R30{degree} phase appears to be nearly independent of temperature below the transition, while the structure of the 1 x 1 phase changes increase rapidly as the phase transition is approached from above. A model for the structure of the 1 x 1 phase with a partially-occupied top Ga layer agrees well with the data. The observed temperature dependence is consistent with a simple model of the equilibrium between the vapor phase and the surface coverage of Ga and N. In addition, the authors present results on the kinetics of reconstruction domain coarsening following a quench into the ({radical}3 x 2{radical}3)R30{degree} phase field.

Munkholm, A.; Thompson, C.; Stephenson, G. B.; Eastman, J. A.; Auciello, O.; Fini, P.; Speck, J. S.; DenBaars, S. P.

2000-01-12T23:59:59.000Z

306

Fabricating Dielecric Ceramic Films on Copper Foils  

Industries Electronics Fabricating Dielectric Ceramic Films on Copper Foils (IN-09-006) Ceramic film capacitors built on a copper foil being tested on ...

307

NIST Hydrogen Storage in Thin Films  

Science Conference Proceedings (OSTI)

Hydrogen Storage Optimization in Thin Film Combinatorial Alloys. ... Magnesium Thin Films," International Journal of Hydrogen Energy, doi:10.1016/j ...

2013-04-01T23:59:59.000Z

308

Thin Film and Nanostructure Processing Group Homepage  

Science Conference Proceedings (OSTI)

... The Thin Film and Nanostructure Processing Group is one of seven ... Deposition of thin films Electrodeposition of metals and alloys Evaporation of ...

2012-10-15T23:59:59.000Z

309

Metals Thin-Films Information at NIST  

Science Conference Proceedings (OSTI)

NIST Home > Metals Thin-Films Information at NIST. Metals Thin-Films Information at NIST. (the links below are a compilation ...

2010-05-24T23:59:59.000Z

310

Optical Characterization of Advanced Thin Films  

Science Conference Proceedings (OSTI)

... Recently, thin films of spun-cast poly(2,5-bis(3-alkylthiophen ... been demonstrated to exhibit exceptional hole mobilities in thin film transistors (TFTs ...

2012-10-02T23:59:59.000Z

311

Surface Sensitive Scattering from Thin Films  

Science Conference Proceedings (OSTI)

... Thin films of few tenths of angstroms are becoming the staple of the electronic ... a powerful tool for the basic understanding of the film microstructure. ...

312

Thin Film Solar Technologies | Open Energy Information  

Open Energy Info (EERE)

Login | Sign Up Search Page Edit with form History Facebook icon Twitter icon Thin Film Solar Technologies Jump to: navigation, search Name Thin Film Solar Technologies...

313

Interfaces in Nanostructured Functional Oxide Thin Films  

Science Conference Proceedings (OSTI)

The thin film systems include high temperature superconductors (HTS), thin film solid oxide fuel cells (SOFC), and other functional oxide systems. Detailed ...

314

Electrical initiation of an energetic nanolaminate film  

DOE Patents (OSTI)

A heating apparatus comprising an energetic nanolaminate film that produces heat when initiated, a power source that provides an electric current, and a control that initiates the energetic nanolaminate film by directing the electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature. Also a method of heating comprising providing an energetic nanolaminate film that produces heat when initiated, and initiating the energetic nanolaminate film by directing an electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature.

Tringe, Joseph W. (Walnut Creek, CA); Gash, Alexander E. (Brentwood, CA); Barbee, Jr., Troy W. (Palo Alto, CA)

2010-03-30T23:59:59.000Z

315

Strictly Bollywood? : story, camera and movement in Hindi film dance  

E-Print Network (OSTI)

Film dances, or filmed dance sequences accompanying film songs, are an important part of popular Indian cinema. Over the years, Hindi film dance has evolved from a cinematically simplistic, filmed documentation of performance ...

Shresthova, Sangita.

2003-01-01T23:59:59.000Z

316

Thin film hydrogen sensor  

DOE Green Energy (OSTI)

A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed.

Lauf, Robert J. (Oak Ridge, TN); Hoffheins, Barbara S. (Knoxville, TN); Fleming, Pamela H. (Oak Ridge, TN)

1994-01-01T23:59:59.000Z

317

Carbonaceous film coating  

DOE Patents (OSTI)

A method of making a carbonaceous film comprising heating tris(1,3,2-benzodiazaborolo)borazine or dodecahydro tris(1,3,2)diazaborine(1,2-a:1'2'-c:1''2''-e)borazine in an inert atmosphere in the presence of a substrate to a temperature at which the borazine compound decomposes, and the decomposition products deposit onto the substrate to form a thin, tenacious, highly reflective conductive coating having a narrow band gap which is susceptible of modification and a relatively low coefficient of friction.

Maya, L.

1988-04-27T23:59:59.000Z

318

System for measuring film thickness  

DOE Patents (OSTI)

A system for determining the thicknesses of thin films of materials exhibiting fluorescence in response to exposure to excitation energy from a suitable source of such energy. A section of film is illuminated with a fixed level of excitation energy from a source such as an argon ion laser emitting blue-green light. The amount of fluorescent light produced by the film over a limited area within the section so illuminated is then measured using a detector such as a photomultiplier tube. Since the amount of fluorescent light produced is a function of the thicknesses of thin films, the thickness of a specific film can be determined by comparing the intensity of fluorescent light produced by this film with the intensity of light produced by similar films of known thicknesses in response to the same amount of excitation energy. The preferred embodiment of the invention uses fiber optic probes in measuring the thicknesses of oil films on the operational components of machinery which are ordinarily obscured from view.

Batishko, Charles R. (West Richland, WA); Kirihara, Leslie J. (Richland, WA); Peters, Timothy J. (Richland, WA); Rasmussen, Donald E. (Richland, WA)

1990-01-01T23:59:59.000Z

319

Thin film ion conducting coating  

DOE Patents (OSTI)

Durable thin film ion conducting coatings are formed on a transparent glass substrate by the controlled deposition of the mixed oxides of lithium:tantalum or lithium:niobium. The coatings provide durable ion transport sources for thin film solid state storage batteries and electrochromic energy conservation devices.

Goldner, Ronald B. (Lexington, MA); Haas, Terry (Sudbury, MA); Wong, Kwok-Keung (Watertown, MA); Seward, George (Arlington, MA)

1989-01-01T23:59:59.000Z

320

Thin films: Past, present, future  

DOE Green Energy (OSTI)

This report describes the characteristics of the thin film photovoltaic modules necessary for an acceptable rate of return for rural areas and underdeveloped countries. The topics of the paper include a development of goals of cost and performance for an acceptable PV system, a review of current technologies for meeting these goals, issues and opportunities in thin film technologies.

Zweibel, K.

1995-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Structure of droplet-epitaxy-grown InAs/GaAs quantum dots  

Science Conference Proceedings (OSTI)

We have used a direct x-ray phasing method, coherent Bragg rod analysis, to obtain sub-angstrom resolution electron density maps of the InAs/GaAs dot system. The dots were grown by the droplet heteroepitaxy (DHE) technique and their structural and compositional properties are compared with those of dots grown by the strain-driven Stranski-Krastanov method. Our results show that the Ga diffusion into the DHE-grown dots is somewhat larger; however, other characteristics such as the composition of the dots uppermost layers, the interlayer spacing, and the bowing of the atomic layers are similar.

Cohen, Eyal; Yochelis, Shira; Westreich, Ohad; Shusterman, Sergey; Kumah, Divine P.; Clarke, Roy; Yacoby, Yizhak; Paltiel, Yossi (Michigan); (Hebrew); (Soreq NRC, Israel)

2011-09-06T23:59:59.000Z

322

Anode film formation and control  

DOE Patents (OSTI)

A protective film is created about the anode within a cryolite-based electrolyte during electrolytic production of aluminum from alumina. The film functions to minimize corrosion of the anode by the cryolitic electrolyte and thereby extend the life of the anode. Various operating parameters of the electrolytic process are controlled to maintain the protective film about the anode in a protective state throughout the electrolytic reduction of alumina. Such parameters include electrolyte temperature, electrolyte ratio, current density, and Al[sub 2]O[sub 3] concentration. An apparatus is also disclosed to enable identification of the onset of anode corrosion due to disruption of the film to provide real time information regarding the state of the film. 3 figs.

Koski, O.; Marschman, S.C.

1990-05-01T23:59:59.000Z

323

Microstructure evolution in TiN films reactively sputter deposited on multiphase substrates  

SciTech Connect

Cross-sectional transmission electron microscopy (X-TEM) has been used to investigate the microstructure of TiN films deposited by reactive magnetron sputtering onto ASP 30 high speed steel (HSS) substrates. ASP 30 is a multiphase material consisting of a martensitic matrix with MC and M/sub 6/C transition--metal particles embedded in it. The TiN films were approx.4 ..mu..m thick and were grown at substrate temperatures T/sub s/ between 200 and 550/sup 0/C. The X-TEM results showed that the film microstructure was very nonhomogeneous. A dense columnar morphology was observed above both the martensitic and M/sub 6/C substrate phases. The average column diameter ranged from 15 nm (T/sub s/ = 200/sup 0/C) to 50 nm (T/sub s/ = 550/sup 0/C) near the film/substrate interface over the martensitic phase and was in a factor of 2 less in the film regions adjacent to the M/sub 6/C phase. increased in both regions to 100 nm (T/sub s/ = 200/sup 0/C) to 150 nm (T/sub s/ = 550/sup 0/C) near the surface of the films. TiN grew epitaxially on MC particles but contained a high dislocation density which (except at 550/sup 0/C where some of the epitaxial grains extended throughout the entire film thickness) eventually coalesced to form low-angle grain boundaries and, finally, high-angle boundaries.

Helmersson, U.; Sundgren, J.; Greene, J.E.

1986-05-01T23:59:59.000Z

324

Growth and structure of photosensitive Pb{sub 1-x}Mn{sub x}Te(Ga) epitaxial films  

Science Conference Proceedings (OSTI)

The growth and structure of (1-1.5)-{mu}m-thick Pb{sub 1-x}Mn{sub x}Te(Ga)(x = 0.06) films with 0.4-0.9 at % of gallium, grown on BaF{sub 2}(111) and Pb{sub 1-x}Sn{sub x}Te (x = 0.2) (100) substrates by molecular beam epitaxy, have been investigated. It is established that the films are crystallized into an fcc structure, and their growth planes are (111) and (100), according to the substrate orientation. The optimal conditions for obtaining high-resistivity photosensitive p-and n-type films with a perfect crystal structure (W{sub 1/2} = 80''-100'') have been determined.

Nuriev, I. R.; Sadygov, R. M.; Nazarov, A. M., E-mail: afinnazarov@yahoo.com [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan)

2008-05-15T23:59:59.000Z

325

Effect of stoichiometry on the dielectric properties and soft mode behavior of strained epitaxial SrTiO3 thin films on DyScO3 substrates  

Science Conference Proceedings (OSTI)

The effect of stoichiometry on the dielectric properties and soft mode behavior of strained epitaxial Sr1-xTiO3 films grown on DyScO3 substrates is reported. Direct comparisons between nominally stoichiometric and non-stoichiometric films have been performed through measurements of lattice parameters, temperature-dependent permittivities, second harmonic generation, and terahertz dielectric spectra. The nominally stoichiometric film shows dispersion-free low-frequency permittivity with a 23 sharp maximum and pronounced soft mode behavior. Our results suggest that strained perfectlystoichiometric SrTiO3 films should not show relaxor behavior and that relaxor behavior emergesfrom defect dipoles that arise from non-stoichiometry in the highly polarizable strained SrTiO3 matrix

Lee, Che-Hui [Pennsylvania State University, University Park, PA; Skoromets, Volodymyr [Institute of Physics, Czech Republic; Biegalski, Michael D [ORNL; Lei, Shiming [Pennsylvania State University, University Park, PA; Haislmaier, Ryan [Pennsylvania State University, University Park, PA; Uecker, Reinhard [Leibniz Institute for Crystal Growth (IKZ); Bernhagen, Margitta [Leibniz Institute for Crystal Growth (IKZ); Xi, Xiaoxing [Temple University; Gopalan, Venkatraman [Pennsylvania State University, University Park, PA; Marti, Xavier [Institute of Physics, Czech Republic; Kamba, Stanislav [Institute of Physics, Czech Republic; Kuzel, Petr [Institute of Physics, Czech Republic; Schlom, Darrell [Cornell University

2013-01-01T23:59:59.000Z

326

Recent progress in nanostructured multiferroic Bi{sub 2}FeCrO{sub 6} thin films  

Science Conference Proceedings (OSTI)

We report the latest progress on the growth and characterization of Bi{sub 2}FeCrO{sub 6} (BFCO), a recently discovered multiferroic system. BFCO thin films and nanostructures exhibit exceptional multiferroic properties at room temperature. The growth of pure BFCO thin films on STO substrates is possible only in a narrow window of deposition parameters (i.e., Oxygen pressure pO{sub 2}=1.2 Multiplication-Sign 10{sup -2} mbar and around a substrate temperature T{sub S}=680 Degree-Sign C). The epitaxial growth stabilizes the metastable single phase of this material and promotes the Fe/Cr cation ordering in both thin films and nanostructures. This cationic ordering which is responsible for good magnetic properties of BFCO is also at the origin of pronounced photovoltaic (PV) properties observed in the epitaxial films grown on STO substrates. The results indicate that the ferroelectric polarization plays a dominant role in the observed PV effect. - Graphical abstract: (Top) Crystal structure of BFCO thin films deposited on (1 1 1)-oriented SrTiO3:Nb substrates and direct evidence of the presence of cationic ordering Fe/Cr in the films. (Bottom) Control of the crystal orientation and the shape of the epitaxial nanostructures by the orientation of the niobium-doped STO substrates. Highlights: Black-Right-Pointing-Pointer Growth optimization of Bi{sub 2}FeCrO{sub 6} (BFCO) thin films and nanostructures by pulsed laser deposition. Black-Right-Pointing-Pointer Ordered BFCO single phase have been stabilized by epitaxial strain. Black-Right-Pointing-Pointer Arbitrary patterns of heteroepitaxial multiferroic BFCO nanostructures have been fabricated by PLD combined with nanostenciling. Black-Right-Pointing-Pointer Experimental characterizations revealed the excellent multiferroic character of BFCO thin films and nanostructures. Black-Right-Pointing-Pointer Unprecedentedly high power conversion efficiency for ferroelectrics was observed in 125 nm-thick highly ordered BFCO films.Graphical abstract legend.

Nechache, Riad, E-mail: Nechache@emt.inrs.ca [NAST Center and Department of Chemical Science and Technology, University of Rome Tor Vergata Via della Ricerca Sceintifica 1, 00133 Rome Italy (Italy); Centre Energie, Materiaux et Telecommunications, INRS, 1650, boulevard Lionel-Boulet, Varennes, Quebec J3x 1S2 (Canada); Rosei, Federico, E-mail: rosei@emt.inrs.ca [Centre Energie, Materiaux et Telecommunications, INRS, 1650, boulevard Lionel-Boulet, Varennes, Quebec J3x 1S2 (Canada)

2012-05-15T23:59:59.000Z

327

Magnetism and transport properties of epitaxial Fe-Ga thin films on GaAs(001)  

SciTech Connect

Epitaxial Fe-Ga thin films in disordered bcc {alpha}-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (M{sub S}) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.

Duong Anh Tuan; Shin, Yooleemi; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Dang Duc Dung [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Department of General Physics, School of Engineering Physics, Ha Noi University of Science and Technology, 1 Dai Co Viet road, Ha Noi (Viet Nam); Vo Thanh Son [Centers for Nanobioenineering and Spintronics, Chungnam National University, Daejon 350-746 (Korea, Republic of)

2012-04-01T23:59:59.000Z

328

Silicate-free growth of high-quality ultrathin cerium oxide films on Si(111)  

Science Conference Proceedings (OSTI)

Ultrathin Ce{sub 2}O{sub 3} layers have been grown on Si(111) by reactive metal deposition in an oxygen background and characterized by x-ray standing waves, x-ray diffraction, x-ray photoelectron spectroscopy, and low-energy electron diffraction to elucidate and quantify both atomic structure and chemical composition. It is demonstrated that highly ordered, mostly B-oriented, epitaxial ceria films can be achieved by preadsorption of a monolayer of atomic chlorine, effectively passivating the substrate and thereby suppressing cerium silicate and silicon oxide formation at the interface.

Flege, Jan Ingo; Kaemena, Bjoern; Wilkens, Torsten; Schmidt, Thomas; Falta, Jens [Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, D-28359 Bremen (Germany); Gevers, Sebastian; Bruns, Daniel; Wollschlaeger, Joachim [Department of Physics, University of Osnabrueck, Barbarastrasse 7, D-49069 Osnabrueck (Germany); Bertram, Florian; Baetjer, Jan [Hamburger Synchrotronstrahlungslabor am Deutschen Elektronensynchrotron, Notkestrasse 85, D-22607 Hamburg (Germany)

2011-12-15T23:59:59.000Z

329

Faraday rotation and sensitivity of (100) bismuth-substituted ferrite garnet films  

E-Print Network (OSTI)

We have investigated the Faraday rotation of in-plane magnetized bismuth-substituted ferrite garnet films grown by liquid phase epitaxy on (100) oriented gadolinium gallium garnet substrates. The Faraday spectra were measured for photon energies between 1.7- 2.6 eV. To interprete the spectra, we use a model based on two electric dipole transitions, one tetrahedral and one octahedral. Furthermore, the Faraday rotation sensitivity was measured at 2.3 eV, and found to be in good agreement with the theoretical predicitions. In particular, we find that the sensitivity increases linearly with the bismuth content and nonlinearly with the gallium content. 1 I.

L. E. Helseth; A. G. Solovyev; R. W. Hansen

2002-01-01T23:59:59.000Z

330

AlGaAsSb/GaSb Distributed Bragg Reflectors Grown by Organometallic Vapor Phase Epitaxy  

SciTech Connect

The first AlGaAsSb/GaSb quarter-wave distributed Bragg reflectors grown by metallic vapor phase epitaxy are reported. The peak reflectance is 96% for a 10-period structure.

C.A. Wang; C.J. Vineis; D.R. Calawa

2002-02-13T23:59:59.000Z

331

Origami-inspired nanofabrication utilizing physical and magnetic properties of in situ grown carbon nanotubes  

E-Print Network (OSTI)

Carbon nanotubes (CNTs), in particular the vertically-aligned variety grown through a plasma enhanced chemical vapor deposition (PECVD)-based process, are highly versatile nanostructures that can be used in a variety of ...

In, Hyun Jin

2010-01-01T23:59:59.000Z

332

Epitaxial VN,,001... Grown and Analyzed In situ by XPS and UPS. II. Analysis of Ar  

E-Print Network (OSTI)

Epitaxial VN,,001... Grown and Analyzed In situ by XPS and UPS. II. Analysis of Ar¿ Sputter Etched-welded to a Mo substrate heater. In Situ Preparation: The epitaxial VN 001 layers were grown in a multichamber that has been shown Ref. 1 to produce sharp 1 1 RHEED patterns. The target, a 5-cm-diam water-cooled V disk

Gall, Daniel

333

Thin Film and nanostructure Processing Staff  

Science Conference Proceedings (OSTI)

Thin Film Nanostructure Staff Directory. John Bonevich, Group Leader. Shari Beauchamp, Office Assistant. STAFF & NRC POSTDOCS. ...

2013-06-11T23:59:59.000Z

334

High quality ultrathin Bi{sub 2}Se{sub 3} films on CaF{sub 2} and CaF{sub 2}/Si by molecular beam epitaxy with a radio frequency cracker cell  

Science Conference Proceedings (OSTI)

We report a method to fabricate high quality Bi{sub 2}Se{sub 3} thin films using molecular beam epitaxy with a radio frequency cracker cell as an atomic selenium source. With Se-to-Bi ratios close to exact stoichiometry, optimal layer-by-layer growth of high quality Bi{sub 2}Se{sub 3} thin films with smooth surfaces has been achieved on CaF{sub 2}(111) substrates and Si(111) substrates with a thin epitaxial CaF{sub 2} buffer layer (CaF{sub 2}/Si). Transport measurements show a characteristic weak-antilocalization magnetoresistance in all the films, with the emergence of a weak-localization contribution in the ultrathin film limit. Quantum oscillations, attributed to the topological surface states have been observed, including in films grown on CaF{sub 2}/Si.

Zhang Li; Dolev, Merav [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Hammond, Robert [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Liu Min [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Palevski, Alexander [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Kapitulnik, Aharon [Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States)

2012-10-08T23:59:59.000Z

335

Utility of reactively sputtered CuN{sub x} films in spintronics devices  

SciTech Connect

We have studied nitrified copper (CuN{sub x}) thin films grown by reactive sputtering in the context of spintronic devices. The Ar-to-N{sub 2} flow ratio enables tunability of the electrical resistivity and surface roughness of the CuN{sub x} films, with the former increasing to nearly 20 times that of Cu, and the latter reduced to the atomic scale. Incorporating this into a Ta/CuN{sub x}/Ta seed stack for spin valves improves the current-in-plane (CIP) magnetoresistance; maximum magnetoresistance results with CuN{sub x} seed layer and Cu interlayer. Finally, finite element modeling results are presented that suggest the use of CuN{sub x} in nanocontact spin torque oscillators can enhance current densities by limiting the current spread through the device. This may positively impact threshold currents, power requirements, and device reliability.

Fang Yeyu [Physics Department, Goeteborg University, 412 96 Goeteborg (Sweden); Persson, J. [Physics Department, Goeteborg University, 412 96 Goeteborg (Sweden); NanOsc AB, Electrum 205, 164 40 Kista (Sweden); Zha, C. [Materials Physics Department, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Willman, J.; Miller, Casey W. [Department of Physics, Center for Integrated Functional Materials, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620 (United States); Aakerman, Johan [Physics Department, Goeteborg University, 412 96 Goeteborg (Sweden); NanOsc AB, Electrum 205, 164 40 Kista (Sweden); Materials Physics Department, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden)

2012-04-01T23:59:59.000Z

336

Waveguiding-assisted random lasing in epitaxial ZnO thin film  

E-Print Network (OSTI)

Zinc Oxide thin films were grown on c-sapphire substrates using pulsed laser deposition. Pump power dependence of surface emission spectra, acquired using a quadrupled 266 nm laser, revealed room temperature stimulated emission (threshold of 900 kW/cm2). Time dependent spectral analysis plus gain measurements of single-shot, side-emission, spectra pumped with a nitrogen laser revealed random lasing indicative of the presence of self-forming laser cavities. It is suggested that random lasing in an epitaxial system rather than a 3-dimensional configuration of disordered scattering elements, was due to waveguiding in the film. Waveguiding causes light to be amplified within randomly-formed closed-loops acting as lasing cavities.

Dupont, P -H; Rogers, D J; Téhérani, F Hosseini; Lérondel, G

2013-01-01T23:59:59.000Z

337

CFN | Thin Films Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Materials Synthesis and Characterization Facility Materials Synthesis and Characterization Facility Thin-Film Processing Facility Online Manager (FOM) website FOM manual ESR for lab 1L32 (High-Resolution SEM and x-ray microanalysis) CFN Operations Safety Awareness (COSA) form for 1L32 (ESR #1) Technical article on LABE detector (Analytical SEM) Request form for off-hours access (.doc, First time only, renewals done via email) Lab Tool capabilities Primary contact Training schedule Backup contact Booking calendar Booking rules SOP 1L32 Analytical SEM Camino Thurs 10-12 PM Stein FOM yes yes Hitachi S-4800 SEM Stein Tues 1-3 PM Black FOM no yes booking calendar: yes = need to reserve tool time in calendar before using tool booking rules: yes = specific rules exist for reserving tool time SOP = standard operating procedure (basic instructions)

338

Liquid-film electron stripper  

DOE Patents (OSTI)

A thin freestanding oil film is produced in vacuum by directing an oil stream radially inward to the hollow-ground sharp outer edge of a rotating disc. The sides of the edge are roughened somewhat to aid in dispersing oil from the disc. Oil is removed from the surface of disc to prevent formation of oil droplets which might spin off the disc and disrupt the oil film. An ion beam is directed through the thin oil film so that electrons are stripped from the ions to increase their charge.

Leemann, B.T.; Yourd, R.B.

1982-03-09T23:59:59.000Z

339

Liquid-film electron stripper  

DOE Patents (OSTI)

A thin freestanding oil film is produced in vacuum by directing an oil stream radially inward to the hollow-ground sharp outer edge of a rotating disc. The sides of the edge are roughened somewhat to aid in dispersing oil from the disc. Oil is removed from the surface of disc to prevent formation of oil droplets which might spin off the disc and disrupt the oil film. An ion beam is directed through the thin oil film so that electrons are stripped from the ions to increase their charge.

Leemann, Beat T. (Walnut Creek, CA); Yourd, Roland B. (Kensington, CA)

1984-01-01T23:59:59.000Z

340

Process for forming planarized films  

DOE Patents (OSTI)

A planarization process and apparatus which employs plasma-enhanced chemical vapor deposition (PECVD) to form plarnarization films of dielectric or conductive carbonaceous material on step-like substrates.

Pang, Stella W. (Arlington, MA); Horn, Mark W. (North Chelmsford, MA)

1991-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Film holder for radiographing tubing  

DOE Patents (OSTI)

A film cassette is provided which may be easily placed about tubing or piping and readily held in place while radiographic inspection is performed. A pair of precurved light-impervious semi-rigid plastic sheets, hinged at one edge, enclose sheet film together with any metallic foils or screens. Other edges are made light-tight with removable caps, and the entire unit is held securely about the object to be radiographed with a releasable fastener such as a strip of Velcro.

Davis, Earl V. (Oak Ridge, TN); Foster, Billy E. (Oak Ridge, TN)

1976-01-01T23:59:59.000Z

342

Issues associated with the metalorganic chemical vapor deposition of ScGaN and YGaN alloys.  

SciTech Connect

The most energy efficient solid state white light source will likely be a combination of individually efficient red, green, and blue LED. For any multi-color approach to be successful the efficiency of deep green LEDs must be significantly improved. While traditional approaches to improve InGaN materials have yielded incremental success, we proposed a novel approach using group IIIA and IIIB nitride semiconductors to produce efficient green and high wavelength LEDs. To obtain longer wavelength LEDs in the nitrides, we attempted to combine scandium (Sc) and yttrium (Y) with gallium (Ga) to produce ScGaN and YGaN for the quantum well (QW) active regions. Based on linear extrapolation of the proposed bandgaps of ScN (2.15 eV), YN (0.8 eV) and GaN (3.4 eV), we expected that LEDs could be fabricated from the UV (410 nm) to the IR (1600 nm), and therefore cover all visible wavelengths. The growth of these novel alloys potentially provided several advantages over the more traditional InGaN QW regions including: higher growth temperatures more compatible with GaN growth, closer lattice matching to GaN, and reduced phase separation than is commonly observed in InGaN growth. One drawback to using ScGaN and YGaN films as the active regions in LEDs is that little research has been conducted on their growth, specifically, are there metalorganic precursors that are suitable for growth, are the bandgaps direct or indirect, can the materials be grown directly on GaN with a minimal defect formation, as well as other issues related to growth. The major impediment to the growth of ScGaN and YGaN alloys was the low volatility of metalorganic precursors. Despite this impediment some progress was made in incorporation of Sc and Y into GaN which is detailed in this report. Primarily, we were able to incorporate up to 5 x 10{sup 18} cm{sup -3} Y atoms into a GaN film, which are far below the alloy concentrations needed to evaluate the YGaN optical properties. After a no-cost extension was granted on this program, an additional more 'liquid-like' Sc precursor was evaluated and the nitridation of Sc metals on GaN were investigated. Using the Sc precursor, dopant level quantities of Sc were incorporated into GaN, thereby concluding the growth of ScGaN and YGaN films. Our remaining time during the no-cost extension was focused on pulsed laser deposition of Sc metal films on GaN, followed by nitridation in the MOCVD reactor to form ScN. Finally, GaN films were deposited on the ScN thin films in order to study possible GaN dislocation reduction.

Koleske, Daniel David; Knapp, James Arthur; Lee, Stephen Roger; Crawford, Mary Hagerott; Creighton, James Randall; Cross, Karen Charlene; Thaler, Gerald

2009-07-01T23:59:59.000Z

343

Variable temperature semiconductor film deposition  

DOE Patents (OSTI)

A method of depositing a semiconductor material on a substrate is disclosed. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

Li, X.; Sheldon, P.

1998-01-27T23:59:59.000Z

344

Microstructure and dielectric properties of piezoelectric magnetron sputtered w-ScxAl1-xN thin films  

Science Conference Proceedings (OSTI)

Piezoelectric wurtzite ScxAl1 xN (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x 0.2 when substrate temperature is increased from 400 to 800 C. The piezoelectric response of epitaxial ScxAl1 xN films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.

Zukauskaite, Agne [Linkoping University; Wingqvist, Gunilla [Linkoping University; Palisaitis, Justinas [Linkoping University; Jensen, Jens [Linkoping University; Persson, Per [Linkoping University; Matloub, Ramin [Ecole Polytechnique Federale de Lausanne, Switzerland; Muralt, Paul [Ecole Polytechnique Federale de Lausanne, Switzerland; Kim, Yunseok [ORNL; Birch, Jens [Linkoping University; Hultman, Lars [Linkoping University

2012-01-01T23:59:59.000Z

345

Fullerene Film as a Coating Material for Silicon Thick Film Anodes ...  

Science Conference Proceedings (OSTI)

Presentation Title, Fullerene Film as a Coating Material for Silicon Thick Film Anodes for Lithium Ion Batteries. Author(s), Arenst Andreas Arie. On-Site Speaker

346

Large-area low-temperature ultrananocrystaline diamond (UNCD) films and integration with CMOS devices for monolithically integrated diamond MEMD/NEMS-CMOS systems.  

SciTech Connect

Because of exceptional mechanical, chemical, and tribological properties, diamond has a great potential to be used as a material for the development of high-performance MEMS and NEMS such as resonators and switches compatible with harsh environments, which involve mechanical motion and intermittent contact. Integration of such MEMS/NEMS devices with complementary metal oxide semiconductor (CMOS) microelectronics will provide a unique platform for CMOS-driven commercial MEMS/NEMS. The main hurdle to achieve diamond-CMOS integration is the relatively high substrate temperatures (600-800 C) required for depositing conventional diamond thin films, which are well above the CMOS operating thermal budget (400 C). Additionally, a materials integration strategy has to be developed to enable diamond-CMOS integration. Ultrananocrystalline diamond (UNCD), a novel material developed in thin film form at Argonne, is currently the only microwave plasma chemical vapor deposition (MPCVD) grown diamond film that can be grown at 400 C, and still retain exceptional mechanical, chemical, and tribological properties comparable to that of single crystal diamond. We have developed a process based on MPCVD to synthesize UNCD films on up to 200 mm in diameter CMOS wafers, which will open new avenues for the fabrication of monolithically integrated CMOS-driven MEMS/NEMS based on UNCD. UNCD films were grown successfully on individual Si-based CMOS chips and on 200 mm CMOS wafers at 400 C in a MPCVD system, using Ar-rich/CH4 gas mixture. The CMOS devices on the wafers were characterized before and after UNCD deposition. All devices were performing to specifications with very small degradation after UNCD deposition and processing. A threshold voltage degradation in the range of 0.08-0.44V and transconductance degradation in the range of 1.5-9% were observed.

Sumant, A.V.; Auciello, O.; Yuan, H.-C; Ma, Z.; Carpick, R. W.; Mancini, D. C.; Univ. of Wisconsin; Univ. of Pennsylvania

2009-05-01T23:59:59.000Z

347

“How Could She?”: The “Inappropriate” Woman in Contemporary Appropriation Films  

E-Print Network (OSTI)

Parrell took a number of porn films that she realized wereintended purposes. Within a porn film, people having sex into most people watching a porn film. Parrell’s film situates

Baron, Jaimie

2010-01-01T23:59:59.000Z

348

Billion-Ton Update: Home-Grown Energy Resources Across the Nation |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Billion-Ton Update: Home-Grown Energy Resources Across the Nation Billion-Ton Update: Home-Grown Energy Resources Across the Nation Billion-Ton Update: Home-Grown Energy Resources Across the Nation August 11, 2011 - 3:59pm Addthis Total potential biomass resources by county in the contiguous U.S. from the baseline scenario of the Update (Figure 6.4, page 159) | Map from Billion-Ton Update Total potential biomass resources by county in the contiguous U.S. from the baseline scenario of the Update (Figure 6.4, page 159) | Map from Billion-Ton Update Paul Bryan Biomass Program Manager, Office of Energy Efficiency & Renewable Energy What does this mean for me? With continued developments in biorefinery capacity and technology, the feedstock resources identified in the report could produce about 85 billion gallons of biofuels -- enough to replace approximately 30 percent

349

Mill study of the quality yield, and mechanical properties of plywood produced from fast-grown loblolly pine  

SciTech Connect

Veneers were cut from 37 fast-grown pines 20-25 year old and from 27 trees with average growth rates in East Texas. After drying, the veneer was used to make plywood panels with a variety of assembly criteria. The yield and grade of veneer were substantially less from the fast-grown trees with a large core of juvenile wood, than from the slower-grown trees of similar size. The greatest reduction was in veneer grade, with fast-grown trees yielding less than 1% of input volume as grade C or better, while control trees exceeded 20%. Plywood made from fast-grown trees had mechanical properties that were marginal for the species, especially in stiffness and MOE. Bending strength was reduced, but less so. It is concluded that use of fast-grown, short-rotation trees will preclude the production of higher grade panels.

MacPeak, M.D.; Burkhart, L.F.; Weldon, D.

1987-01-01T23:59:59.000Z

350

Silicon-Germanium Films Deposited by Low Frequency PE CVD: Effect of H2 and Ar Dilution  

DOE Green Energy (OSTI)

We have studied structure and electrical properties of Si{sub 1-Y}Ge{sub Y}:H films deposited by low frequency PE CVD over the entire composition range from Y=0 to Y=1. The deposition rate of the films and their structural and electrical properties were measured for various ratios of the germane/silane feed gases and with and without dilution by Ar and by H{sub 2}. Structure and composition was studied by Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS) and Fourier transform infrared (FTIR) spectroscopy. Surface morphology was characterized by atomic force microscopy (AFM). We found: (1) The deposition rate increased with Y maximizing at Y=1 without dilution. (2) The relative rate of Ge and Si incorporation is affected by dilution. (3) Hydrogen preferentially bonds to silicon. (4) Hydrogen content decreases for increasing Y. In addition, optical measurements showed that as Y goes for 0 to 1, the Fermi level moves from mid gap to the conduction band edge, i.e. the films become more n-type. No correlation was found between the pre-exponential and the activation energy of conductivity. The behavior of the conductivity {gamma}-factor suggests a local minimum in the density of states at E {approx} 0.33 eV for the films grown with or without H-dilution and E {approx} 0.25 eV for the films with Ar dilution.

Kosarev, A; Torres, A; Hernandez, Y; Ambrosio, R; Zuniga, C; Felter, T E; Asomoza, R R; Kudriavtsev, Y; Silva-Gonzalez, R; Gomez-Barojas, E; Ilinski, A; Abramov, A S

2005-09-22T23:59:59.000Z

351

Monolithically interconnected Silicon-Film{trademark} module technology: Annual technical report, 25 November 1997--24 November 1998  

DOE Green Energy (OSTI)

AstroPower continued its development of an advanced thin-silicon-based photovoltaic module product. This module combines the performance advantages of thin, light-trapped silicon layers with the capability of integration into a low-cost, monolithically interconnected array. This report summarizes the work carried out over the first year of a three-year, cost-shared contract, which has yielded the following results: Development of a low-cost, insulating, ceramic substrate that provides mechanical support at silicon growth temperatures, is matched to the thermal expansion of silicon, provides the optical properties required for light trapping through random texturing, and can be formed in large areas on a continuous basis. Different deposition techniques have been investigated, and AstroPower has developed deposition processes for the back conductive layer, the p-type silicon layer, and the mechanical/chemical barrier layer. Polycrystalline films of silicon have been grown on ceramics using AstroPower's Silicon-Film{trademark} process. These films are from 50 to 75 {micro}m thick, with columnar grains extending through the thickness of the film. Aspect ratios from 5:1 to 20:1 have been observed in these films.

Hall, R.B.; Ford, D.H.; Rand, J.A.; Ingram, A.E.

1999-11-11T23:59:59.000Z

352

Electrical and gas-sensitive properties of nanostructured SnO{sub 2}:ZrO{sub 2} semiconductor films  

Science Conference Proceedings (OSTI)

The results of a study of the effect of atomic composition of metal-oxide semiconductor composites SnO{sub 2}:ZrO{sub 2} on the surface morphology, polycrystal grain size, resistivity, concentration, free-carrier mobility, and gas-sensitive properties of thin films (0.5-2.5 {mu}m) are presented. Films SnO{sub 2} with ZrO{sub 2} additives (the Zr content was varied from 0.5 to 4.6 at %) are grown by reactive ion-beam sputtering of metal targets of different compositions in a controlled Ar + O{sub 2} atmosphere. Using transmission electron microscopy, atomic-force microscopy, and high-resolution transmission electron microscopy, it is experimentally shown that, as the Zr content increases in the SnO{sub 2}:ZrO{sub 2} film composition, the polycrystal grain size decreases from 45 to 10 nm, the free-carrier concentration decreases almost by four orders of magnitude and the mobility increases by approximately nine times. As the Zr content increases in the SnO{sub 2}:ZrO{sub 2} film from 0.5 to 4.6 at %, the temperature of maximum gas sensitivity of films to such gases as ethanol, isopropyl alcohol, and acetone decreases by 100-190 Degree-Sign C.

Rembeza, S. I., E-mail: rembeza@yandex.ru; Kosheleva, N. N.; Rembeza, E. S.; Svistova, T. V.; Shmatova, Yu. V. [Voronezh State Technical University (Russian Federation); Xu Gang [Tsinghua University (China)

2011-05-15T23:59:59.000Z

353

Applications of Passive Thin Films  

DOE Green Energy (OSTI)

The physical properties of thin films affect the performance and durability of nearly every solar energy conversion device. Familiar examples of thin films for solar applications are optical materials and protective coatings. Optimized optical properties are key to cost-effective photothermal conversion where individual components must have high absorptance, reflectance, or transmittance. The protection of sensitive substrates from corrosion and/or erosion is essential to ensure adequate component and system lifetime. Such substrates range from photovoltaic materials operating near room temperature to turbine blade structural alloys in hostile environments at very high temperatures (>1,000 degrees C). Although much has been written on particular categories of thin-film materials for solar energy (for example, absorbers for receiver surfaces), to date no one has provided an overview of the spectrum of applications for passive thin films in solar energy. This work is such an overview and also reviews the material state of the art as described in the current literature. Active thin film devices such as photovoltaics and thermoeleetrics are not discussed.

Call, P. J.

1979-05-01T23:59:59.000Z

354

Semiconductor-nanocrystal/conjugated polymer thin films  

DOE Patents (OSTI)

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Alivisatos, A. Paul (Oakland, CA); Dittmer, Janke J. (Munich, DE); Huynh, Wendy U. (Munich, DE); Milliron, Delia (Berkeley, CA)

2010-08-17T23:59:59.000Z

355

Biaxially Oriented Film on Flexible Polymeric Substrate  

LANL’s Aligned-Crystalline Silicon (ACSi) technology provides highly crystalline silicon films on inexpensive substrates, such as metal sheets and glass plates.  ACSi films exhibit good electrical and optical properties and have the potential to make ...

356

Thin film-coated polymer webs  

DOE Patents (OSTI)

The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

Wenz, Robert P. (Cottage Grove, MN); Weber, Michael F. (Shoreview, MN); Arudi, Ravindra L. (Woodbury, MN)

1992-02-04T23:59:59.000Z

357

Addressing PQ Issues at a Film Manufacturer  

Science Conference Proceedings (OSTI)

This case study contains the details of an on-site power quality audit of a film manufacturer which was experiencing voltage sags that led to the shutdown of film processing.

2007-12-31T23:59:59.000Z

358

Laser tracks in rainbow films on water  

Science Conference Proceedings (OSTI)

It is found that narrow non-diverging laser tracks, earlier studied in free soap films, can also arise in thin rainbow films, e.g., of petrol, on water. (laser applications and other topics in quantum electronics)

Startsev, Aleksandr V; Stoilov, Yurii Yu [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2012-08-31T23:59:59.000Z

359

Thin Film Deposition Method for Sensor Manufacturing  

Scientists at Los Alamos National Laboratory (LANL) have developed an innovative method for gas sensor manufacturing using a thin film deposition. The thin film requires very little material and can be applied in high throughput applications.

360

Thin Film Photovoltaics - Programmaster.org  

Science Conference Proceedings (OSTI)

Thin Film Structures for Energy Efficient Systems: Thin Film Photovoltaics ... Full- inorganic Heterojunction Ink-printed Solar Cells: Seigo Ito1; 1University of Hyogo ... electrochemical impedance spectroscopy (EIS) measurements were used for ...

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Electrostatic thin film chemical and biological sensor  

DOE Patents (OSTI)

A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includes providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.

Prelas, Mark A. (Columbia, MO); Ghosh, Tushar K. (Columbia, MO); Tompson, Jr., Robert V. (Columbia, MO); Viswanath, Dabir (Columbia, MO); Loyalka, Sudarshan K. (Columbia, MO)

2010-01-19T23:59:59.000Z

362

Corner Flows in Free Liquid Films  

E-Print Network (OSTI)

A lubrication-flow model for a free film in a corner is presented. The model, written in the hyperbolic coordinate system ? = x² – y², η = 2xy, applies to films that are thin in the η direction. The lubrication approximation ...

Stocker, Roman

2004-08-24T23:59:59.000Z

363

Thin-film Lithium Batteries  

NLE Websites -- All DOE Office Websites (Extended Search)

Thin-Film Battery with Lithium Anode Courtesy of Oak Ridge National Laboratory, Materials Science and Technology Division Thin-Film Lithium Batteries Resources with Additional Information The Department of Energy's 'Oak Ridge National Laboratory (ORNL) has developed high-performance thin-film lithium batteries for a variety of technological applications. These batteries have high energy densities, can be recharged thousands of times, and are only 10 microns thick. They can be made in essentially any size and shape. Recently, Teledyne licensed this technology from ORNL to make batteries for medical devices including electrocardiographs. In addition, new "textured" cathodes have been developed which have greatly increased the peak current capability of the batteries. This greatly expands the potential medical uses of the batteries, including transdermal applications for heart regulation.'

364

Magnetoelectric Multiferroic Thin Films and Multilayers  

Science Conference Proceedings (OSTI)

Scope, The symposium will cover thin films, single crystals, normal/relaxor ferroelectrics, piezoelectric ceramics, magnetoelectric composites, multiferroic ...

365

Magnetic behaviour of europium epitaxial thin films  

Science Conference Proceedings (OSTI)

... Magnetic behaviour of europium epitaxial thin films. Philippe Mangin, University of Nancy and NCNR. We present the magnetic ...

366

MST: Organizations: Thin Film, Vacuum, and Packaging  

NLE Websites -- All DOE Office Websites (Extended Search)

Processes & Services Electronic Fabrication Manufacturing Process Science & Technology Thin Film, Vacuum, & Packaging Organic Materials Ceramic & Glass Meso Manufacturing &...

367

Epitaxial Fe{sub 3-x}Ti{sub x}O{sub 4} films from magnetite to ulvöspinel by pulsed laser deposition  

SciTech Connect

Epitaxial films along the Fe{sub 3-x}Ti{sub x}O{sub 4} (titanomagnetite) compositional series from pure end-members magnetite (Fe{sub 3}O{sub 4}) to ulvöspinel (Fe{sub 2}TiO{sub 4}) were successfully grown by pulsed laser deposition on MgO(100) substrates. Spectroscopic characterization including high resolution x-ray diffraction, x-ray photoelectron spectroscopy, and synchrotron-based x-ray absorption and magnetic circular dichroism consistently shows that Ti(IV) substitutes for Fe(III) in the inverse spinel lattice with a proportional increase in lattice Fe(II) concentration. No evidence of Ti interstitials, spinodal decomposition, or secondary phases was found in the bulk of the grown films. At the uppermost few nanometers of the Ti-bearing film surfaces, evidence suggests that Fe(II) is susceptible to facile oxidation, and that an associated lower Fe/Ti ratio in this region is consistent with surface compositional incompleteness or alteration to a titanomaghemite-like composition and structure. The surface of these films nonetheless appear to remain highly ordered and commensurate with the underlying structure despite facile oxidation, a surface condition that is found to be reversible to some extent by heating in low oxygen environments.

Droubay, T.C.; Pearce, C.I.; Ilton, E.S.; Engelhard, M.H.; Engelhard, M.H.; Heald, S.M.; Arenholz, E.; Rosso, K.M.

2011-07-21T23:59:59.000Z

368

Thin film buried anode battery  

DOE Patents (OSTI)

A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

Lee, Se-Hee (Lakewood, CO); Tracy, C. Edwin (Golden, CO); Liu, Ping (Denver, CO)

2009-12-15T23:59:59.000Z

369

Film informing design for contemplative gameplay  

Science Conference Proceedings (OSTI)

Borrowing from film and filmmaking styles, techniques and devices that manipulate spectators' attention and experience, this paper proposes an approach to inform design of games and gameplay to manipulate player's focus of attention and encourage contemplation ... Keywords: Asian film, French New Wave, continuity style, engagement, experience, film theory, filmmaking, game design, interruption, machinima, mixed reality, reflection, serious games

Tim Marsh; Michael Nitsche; Wei Liu; Peichi Chung; Jay D. Bolter; Adrian D. Cheok

2008-08-01T23:59:59.000Z

370

Method of producing thin cellulose nitrate film  

DOE Patents (OSTI)

An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent.

Lupica, S.B.

1975-12-23T23:59:59.000Z

371

Solution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes  

E-Print Network (OSTI)

that lower- ing the price of batteries is a major goal, the cost of the processing and fabricationSolution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes Candace K. Chan, Reken N. Patel interest in using nanomaterials for advanced lithium-ion battery electrodes, par- ticularly for increasing

Cui, Yi

372

Layer Number Determination and Thickness-Dependent Properties of Graphene Grown on SiC  

Science Conference Proceedings (OSTI)

The electronic properties of few-layer graphene grown on the carbon face of silicon carbide (SiC) are found to be strongly dependent on the number of layers. The carrier mobility is larger in thicker graphene because substrate-related scattering is reduced ...

Wenjuan Zhu; Christos Dimitrakopoulos; Marcus Freitag; Phaedon Avouris

2011-09-01T23:59:59.000Z

373

Direct Evidence for the Suppression of Charge Stripes in Epitaxial {La1.67Sr0.33NiO4} Films  

Science Conference Proceedings (OSTI)

We have successfully grown epitaxial La1.67Sr0.33NiO4 films with a small crystalline mosaic using pulsed laser deposition. With synchrotron radiation, the x-ray-diffraction peaks associated with charge stripes have been successfully observed for relatively thick films. Anomalies due to the charge-ordering transition have been examined using four-point probe resistivity measurements. X-ray scattering provides direct evidence for suppression of the stripe phase in thinner samples; the phase disappears for film thicknesses 2600 Angstroms. The suppression appears to be a result of shrinking the stripe phase domains. This may reflect the stripe phase progressing from nematic to isotropic.

Xie,C.; Budnick, J.; Hines, W.; Wells, B.; He, F.; Moodenbaugh, A.

2008-01-01T23:59:59.000Z

374

Strain relaxation in GaN/Al{sub x}Ga{sub 1-x}N superlattices grown by plasma-assisted molecular-beam epitaxy  

SciTech Connect

We have investigated the misfit relaxation process in GaN/Al{sub x}Ga{sub 1-x}N (x = 0.1, 0.3, 0.44) superlattices (SL) deposited by plasma-assisted molecular beam epitaxy. The SLs under consideration were designed to achieve intersubband absorption in the mid-infrared spectral range. We have considered the case of growth on GaN (tensile stress) and on AlGaN (compressive stress) buffer layers, both deposited on GaN-on-sapphire templates. Using GaN buffer layers, the SL remains almost pseudomorphic for x = 0.1, 0.3, with edge-type threading dislocation densities below 9 x 10{sup 8} cm{sup -2} to 2 x 10{sup 9} cm{sup -2}. Increasing the Al mole fraction to 0.44, we observe an enhancement of misfit relaxation resulting in dislocation densities above 10{sup 10} cm{sup -2}. In the case of growth on AlGaN, strain relaxation is systematically stronger, with the corresponding increase in the dislocation density. In addition to the average relaxation trend of the SL, in situ measurements indicate a periodic fluctuation of the in-plane lattice parameter, which is explained by the different elastic response of the GaN and AlGaN surfaces to the Ga excess at the growth front. The results are compared with GaN/AlN SLs designed for near-infrared intersubband absorption.

Kotsar, Y.; Bellet-Amalric, E.; Das, A.; Monroy, E. [CEA-Grenoble, INAC/SP2M/NPSC, 17 Rue des Martyrs, 38054 Grenoble cedex 9 (France); Doisneau, B. [SIMaP, Grenoble INP, Domaine Universitaire, BP 75, 38402 Saint Martin d'Heres (France); Sarigiannidou, E. [LMGP, Grenoble INP, 3 Parvis Louis Neel, BP 257, 38016 Grenoble cedex 1 (France)

2011-08-01T23:59:59.000Z

375

Thermoplastic film prevents proppant flowback  

Science Conference Proceedings (OSTI)

Thermoplastic film added to proppants is effective and economical for preventing proppant flowback after an hydraulic fracturing treatment. Most other methods, such as resin-coated proppant and fiber, for controlling proppant flowback have drawbacks that added to treatment costs by requiring long downtime, costly additives, or frequent equipment replacement. Thermoplastic film does not react chemically with fracturing fluids. After the proppant is placed in the fracture, the film strips intertwine with the proppant grains or at higher temperatures, the strips become adhesive and shrink forming consolidated clusters that hold open the newly created fractures and prevent proppant from flowing back. The low cost of the film means that the strips can be used throughout the fracturing job or in selected stages. The strips are compatible with fracturing fluid chemistry, including breakers and crosslinkers, and can be used in wells with a wide range of bottom hole temperatures. The end result is a well that can be brought back on-line in a short time with little proppant flowback. This paper reviews the cost benefits and performance of these proppants.

Nguyen, P.D.; Weaver, J.D.; Parker, M.A.; King, D.G. [Halliburton Energy Services, Duncan, OK (United States)

1996-02-05T23:59:59.000Z

376

Methane production by attached film  

DOE Patents (OSTI)

A method for purifying wastewater of biodegradable organics by converting the organics to methane and carbon dioxide gases is disclosed, characterized by the use of an anaerobic attached film expanded bed reactor for the reaction process. Dilute organic waste material is initially seeded with a heterogeneous anaerobic bacteria population including a methane-producing bacteria. The seeded organic waste material is introduced into the bottom of the expanded bed reactor which includes a particulate support media coated with a polysaccharide film. A low-velocity upward flow of the organic waste material is established through the bed during which the attached bacterial film reacts with the organic material to produce methane and carbon dioxide gases, purified water, and a small amount of residual effluent material. The residual effluent material is filtered by the film as it flows upwardly through the reactor bed. In a preferred embodiment, partially treated effluent material is recycled from the top of the bed to the bottom of the bed for further treatment. The methane and carbon dioxide gases are then separated from the residual effluent material and purified water.

Jewell, William J. (202 Eastwood Ave., Ithaca, NY 14850)

1981-01-01T23:59:59.000Z

377

Causes of Paint Film Defects  

Science Conference Proceedings (OSTI)

Table 9   Common causes of paint film defects...Dip, flow, roller, spray Improper applicator/metering roll speeds Roller Undesirable pattern Swelling of roll Roller Roll improperly ground Roller Foreign material on roll Roller Poor spray gun technique Spray Runs (curtains, sags) Too much solvent Dip, flow, spray Paint surface or drying atmosphere...

378

Carbon film electrodes for super capacitor applications  

DOE Patents (OSTI)

A microporous carbon film for use as electrodes in energy strorage devices is disclosed, which is made by the process comprising the steps of: (1) heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and (2) activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm.sup.2 and 1 g/cm.sup.2 and a gravimetric capacitance of about between 120 F/g and 315 F/g.

Tan, Ming X. (Livermore, CA)

1999-01-01T23:59:59.000Z

379

Carbon Film Electrodes For Super Capacitor Applications  

DOE Patents (OSTI)

A method for treating an organic polymer material, preferably a vinylidene chloride/vinyl chloride copolymer (Saran) to produce a flat sheet of carbon film material having a high surface area (.apprxeq.1000 m.sup.2 /g) suitable as an electrode material for super capacitor applications. The method comprises heating a vinylidene chloride/vinyl chloride copolymer film disposed between two spaced apart graphite or ceramic plates to a first temperature of about 160.degree. C. for about 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, thereafter heating the stabilized film to a second temperature of about 750.degree. C. in an inert atmosphere for about one hour to form a carbon film; and finally activating the carbon film to increase the surface area by heating the carbon film in an oxidizing atmosphere to a temperature of at least 750-850.degree. C. for between 1-6 hours.

Tan, Ming X. (Livermore, CA)

1999-07-20T23:59:59.000Z

380

Biaxially-Textured Photovoltaic Film Crystal Silicon on Ion Beam Assisted Deposition CaF2 Seed Layers on Glass  

SciTech Connect

We grow biaxially textured heteroepitaxial crystal silicon (c-Si) films on display glass as a low-cost photovoltaic material. We first fabricate textured CaF{sub 2} seed layers using ion-beam assisted deposition, then coat the CaF{sub 2} with a thin, evaporated epitaxial Ge buffer and finally deposit heteroepitaxial silicon on the Ge. The silicon is grown by hot-wire chemical vapor deposition, a high-rate, scalable epitaxy technology. Electron and X-ray diffraction confirm the biaxial texture of the CaF{sub 2} and epitaxial growth of the subsequent layers. Transmission electron microscopy reveals columnar silicon grains about 500 nm across. We fabricate a proof-of-concept epitaxial film c-Si solar cell with an open circuit voltage of 375 mV that is limited by minority carrier lifetime.

Groves, J. R.; Li, J. B.; Clemens, B. M.; LaSalvia, V.; Hasoon, F.; Branz, H. M.; Teplin, C. W.

2012-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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381

Surfactant-Assisted Growth of CdS Thin Films for Photovoltaic Applications  

SciTech Connect

A common non-ionic surfactant, Triton X-100, was used to modify the chemical bath deposition (CBD) of CdS "buffer" layers on Cu(In,Ga)Se2 (CIGS) thin films. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) data demonstrate that films produced with the surfactant have about the same levels of impurities as films grown without it. For thin, ~130 ..ANG.. CdS layers and relative to devices made without the surfactant, average absolute cell efficiencies were increased from 10.5% to 14.8%, or by a relative 41%. Visual inspection of the CdS depositions reveals one possible mechanism of the surfactant's effects: bubbles that form and adhere to the CIGS surface during the CBD reaction are almost completely eliminated with the addition of the TX-100. Thus, pinholes and thin areas in the CdS layers caused by poor wetting of the substrate surface are sharply reduced, leading to large increases in the open circuit voltage in devices produced with the surfactant.

Perkins, C. L.; Hasoon, F. S.

2005-11-01T23:59:59.000Z

382

Surfactant-Assisted Growth of CdS Thin Films for Photovoltaic Applications  

DOE Green Energy (OSTI)

A common non-ionic surfactant, Triton X-100, was used to modify the chemical bath deposition (CBD) of CdS "buffer" layers on Cu(In,Ga)Se2 (CIGS) thin films. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) data demonstrate that films produced with the surfactant have about the same levels of impurities as films grown without it. For thin, ~130 ..ANG.. CdS layers and relative to devices made without the surfactant, average absolute cell efficiencies were increased from 10.5% to 14.8%, or by a relative 41%. Visual inspection of the CdS depositions reveals one possible mechanism of the surfactant's effects: bubbles that form and adhere to the CIGS surface during the CBD reaction are almost completely eliminated with the addition of the TX-100. Thus, pinholes and thin areas in the CdS layers caused by poor wetting of the substrate surface are sharply reduced, leading to large increases in the open circuit voltage in devices produced with the surfactant.

Perkins, C. L.; Hasoon, F. S.

2005-11-01T23:59:59.000Z

383

Processing and Characterization of P-Type Doped Zinc Oxide Thin Films  

E-Print Network (OSTI)

Applications of zinc oxide (ZnO) for optoelectronic devices, including light emitting diodes, semiconductor lasers, and solar cells have not yet been realized due to the lack of high-quality p-type ZnO. In the research presented herein, pulsed laser deposition is employed to grow Ag-doped ZnO thin films, which are characterized in an attempt to understand the ability of Ag to act as a p-type dopant. By correlating the effects of the substrate temperature, oxygen pressure, and laser energy on the electrical and microstructural properties of Ag-doped ZnO films grown on c-cut sapphire substrates, p-type conductivity is achieved under elevated substrate temperatures. Characteristic stacking fault features have been continuously observed by transmission electron microscopy in all of the p-type films. Photoluminescence studies on n-type and p-type Ag-doped ZnO thin films demonstrate the role of stacking faults in determining the conductivity of the films. Exciton emission attributed to basal plane stacking faults suggests that the acceptor impurities are localized nearby the stacking faults in the n-type films. The photoluminescence investigation provides a correlation between microstructural characteristics and electrical properties of Ag- doped ZnO thin films; a link that enables further understanding of the doping nature of Ag impurities in ZnO. Under optimized deposition conditions, various substrates are investigated as potential candidates for ZnO thin film growth, including r -cut sapphire, quartz, and amorphous glass. Electrical results indicated that despite narrow conditions for obtaining p-type conductivity at a given substrate temperature, flexibility in substrate choice enables improved electrical properties. In parallel, N+-ion implantation at elevated temperatures is explored as an alternative approach to achieve p-type ZnO. The ion implantation fluence and temperature have been optimized to achieve p-type conductivity. Transmission electron microscopy reveals that characteristic stacking fault features are present throughout the p-type films, however in n-type N-doped films high-density defect clusters are observed. These results suggest that the temperature under which ion implantation is performed plays a critical role in determining the amount of dynamic defect re- combination that can take place, as well as defect cluster formation processes. Ion implantation at elevated temperatures is shown to be an effective method to introduce increased concentrations of p-type N dopants while reducing the amount of stable post-implantation disorder. Finally, the fabrication and properties of p-type Ag-doped ZnO/n-type ZnO and p-type N-doped ZnO/n-type ZnO thin film junctions were reported. For the N-doped sample, a rectifying behavior was observed in the I-V curve, consistent with N-doped ZnO being p-type and forming a p-n junction. The turn-on voltage of the device was ?2.3 V under forward bias. The Ag-doped samples did not result in rectifying behavior as a result of conversion of the p-type layer to n-type behavior under the n- type layer deposition conditions. The systematic studies in this dissertation provide possible routes to grow p-type Ag-doped ZnO films and in-situ thermal activation of N-implanted dopant ions, to overcome the growth temperature limits, and to push one step closer to the future integration of ZnO-based devices.

Myers, Michelle Anne

2013-05-01T23:59:59.000Z

384

Transparent Conductors and Barrier Layers for Thin Film Solar Cells:  

DOE Green Energy (OSTI)

This report describes the research undertaken to increase the efficiency of thin-film solar cells based on amorphous silicon in the so-called''superstrate structure'' (glass front surface/transparent electrically conductive oxide (TCO)/pin amorphous silicon/metal back electrode). The TCO layer must meet many requirements: high optical transparency in the wavelength region from about 350 to 900 nm, low electrical sheet resistance, stability during handling and deposition of the subsequent layers and during use, a textured (rough) surface to enhance optical absorption of red and near-infrared light, and low-resistance electrical contact to the amorphous silicon p-layer. Fluorine-doped tin oxide has been the TCO used in most commercial superstrate amorphous silicon cells. Fluorine-doped zinc oxide (ZnO:F) was later shown to be even more transparent than fluorine-doped tin oxide, as well as being more resistant to the strongly reducing conditions encountered during the deposition of amorphous silicon. Solar cells based on ZnO:F showed the expected higher currents, but the fill factors were lower than standard cells grown on tin oxide, resulting in no consistent improvement in efficiency. This problem was recently mitigated by using a new proprietary p/buffer layer combination developed at BP Solar.

Gordon, R. G.; Broomhall-Dillard, R.; Liu, X.; Pang, D.; Barton, J.

2001-12-01T23:59:59.000Z

385

Comparison of electronic structure of as grown and solar grade silicon samples  

Science Conference Proceedings (OSTI)

A comparison of the electronic structure of two different types of silicon materials viz., (i) as grown silicon and (ii) solar silicon has been carried out utilizing maximum entropy method and pair distribution function using powder X-ray data sets. The precise electron density maps have been elucidated for the two samples. The covalent nature of the bonding between atoms in both the samples is found to be well pronounced and clearly seen from the electron density maps. The electron densities at the middle of the Si-Si bond are found to be 0.47 and 0.45 e/A{sup 3} for as grown silicon and solar silicon respectively. In this work, the local structural information has also been obtained by analyzing the atomic pair distribution functions of these two samples.

Saravanan, R., E-mail: saragow@dataone.in; Sheeba, R. A. J. R. [Madura College, Research Centre and PG Department of Physics (India)

2012-04-15T23:59:59.000Z

386

Vapor deposition of thin-film Y-doped ZrO{sub 2} for electrochemical device applications  

DOE Green Energy (OSTI)

Solid oxide electrolytes based on yttria-stabilized zirconia (YSZ) are widely used in applications such as oxygen sensors, solid oxide fuel cells, oxygen pumps, electrocatalytic reactors, and electrochemically driven oxygen separation membranes. However, bulk YSZ is used in these applications. This requires high operating temperatures in order to minimize ohmic loss. One alternative of overcoming this problem is to use a thin film of the electrolyte. In the work, the authors have grown polycrystalline thin films of fully stabilized Y-ZrO{sub 2} on thick porous Al{sub 2}O{sub 3} substrates in multilayer La{sub 1{minus}x}Sr{sub x}MEO{sub 3}YSZ/La{sub 1{minus}x}Sr{sub x}MEO{sub 3} (ME = Mn, Co) configurations using a combination of single-target RF magnetron sputtering and electron beam physical vapor deposition techniques. The structure and morphology of these films have been studied using X-ray diffraction, and Scanning Electron Microscopy techniques. The ionic conductivity of the thin films has been measured using AC impedance analysis.

Chung, B.W.; Brosha, E.L.; Brown, D.R.; Garzon, F.H.

1994-12-01T23:59:59.000Z

387

Microstructure and dielectric properties of piezoelectric magnetron sputtered w-Sc{sub x}Al{sub 1-x}N thin films  

Science Conference Proceedings (OSTI)

Piezoelectric wurtzite Sc{sub x}Al{sub 1-x}N (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al{sub 2}O{sub 3}(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 deg. C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 deg. C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x {>=} 0.2 when substrate temperature is increased from 400 to 800 deg. C. The piezoelectric response of epitaxial Sc{sub x}Al{sub 1-x}N films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.

Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas; Jensen, Jens; Persson, Per O. A.; Birch, Jens; Hultman, Lars [Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping (Sweden); Matloub, Ramin; Muralt, Paul [Ceramics Laboratory, Ecole Polytechnique Federale de Lausanne EPFL, Lausanne (Switzerland); Kim, Yunseok [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2012-05-01T23:59:59.000Z

388

Atomic layer deposition of Al2O3 on V2O5 xerogel film for enhanced lithium-ion intercalation stability  

SciTech Connect

V2O5 xerogel films were fabricated by casting V2O5 sols onto fluorine-doped tin oxide glass substrates at room temperature. Five, ten and twenty atomic layers of Al2O3 were grown onto as-fabricated films respectively. The bare film and Al2O3-deposited films all exhibited hydrous V2O5 phase only. Electrochemical impedance spectroscopy study revealed increased surface charge-transfer resistance of V2O5 films as more Al2O3 atomic layers were deposited. Lithium-ion intercalation tests at 600 mAg_1 showed that bare V2O5 xerogel film possessed high initial discharge capacity of 219 mAhg_1 but suffered from severe capacity degradation, i.e., having only 136 mAhg_1 after 50 cycles. After deposition of ten atomic layers of Al2O3, the initial discharge capacity was 195 mAhg_1 but increased over cycles before stabilizing; after 50 cycles, the discharge capacity was as high as 225 mAhg_1. The noticeably improved cyclic stability of Al2O3-deposited V2O5 xerogel film could be attributed to the improved surface chemistry and enhanced mechanical strength. During repeated lithium-ion intercalation/de-intercalation, atomic layers of Al2O3 which were coated onto V2O5 surface could prevent V2O5 electrode dissolution into electrolyte by reducing direct contact between active electrode and electrolyte while at the same time acting as binder to maintain good mechanical contact between nanoparticles inside the film. VC 2012 American Vacuum Society.

Liu, Dawei; Liu, Yanyi; Candelaria, Stephanie L.; Cao, Guozhong; Liu, Jun; Jeong, Yoon-Ha

2012-01-29T23:59:59.000Z

389

Biaxially Oriented Film on Flexible Polymeric Substrate  

NLE Websites -- All DOE Office Websites (Extended Search)

Biaxially Oriented Film on Flexible Polymeric Substrate Biaxially Oriented Film on Flexible Polymeric Substrate Biaxially Oriented Film on Flexible Polymeric Substrate A semiconducting structure having a glass substrate. Available for thumbnail of Feynman Center (505) 665-9090 Email Biaxially Oriented Film on Flexible Polymeric Substrate LANL's Aligned-Crystalline Silicon (ACSi) technology provides highly crystalline silicon films on inexpensive substrates, such as metal sheets and glass plates. ACSi films exhibit good electrical and optical properties and have the potential to make an impact on the solar cell industry. The current ACSi prototype, designed under subpar tooling conditions in a non-optimal environment, already demonstrates 2% conversion efficiency. U.S. Patent No.: 7,601.430 (DOE S-104,959) Patent Application Filing Date: January 31, 2006

390

Thin-film rechargeable lithium batteries  

SciTech Connect

Small thin-film rechargeable cells have been fabricated with a lithium phosphorus oxyniuide electrolyte, Li metal anode, and Li{sub 1-x}Mn{sub 2}O{sub 4} as the cathode film. The cathode films were fabricated by several different techniques resulting in both crystalline and amorphous films. These were compared by observing the cell discharge behavior. Estimates have been made for the scale-up of such a thin-film battery to meet the specifications for the electric vehicle application. The specific energy, energy density, and cycle life are expected to meet the USABC mid-term criteria. However, the areas of the thin-films needed to fabricate such a cell are very large. The required areas could be greatly reduced by operating the battery at temperatures near 100{degrees}C or by enhancing the lithium ion transport rate in the cathode material.

Dudney, N.J.; Bates, J.B.; Lubben, D.

1994-11-01T23:59:59.000Z

391

Ambient-pressure silica aerogel films  

SciTech Connect

Very highly porous (aerogel) silica films with refractive index in the range 1.006--1.05 (equivalent porosity 98.5--88%) were prepared by an ambient-pressure process. It was shown earlier using in situ ellipsometric imaging that the high porosity of these films was mainly attributable to the dilation or `springback` of the film during the final stage of drying. This finding was irrefutably reconfirmed by visually observing a `springback` of >500% using environmental scanning electron microscopy (ESEM). Ellipsometry and ESEM also established the near cent per cent reversibility of aerogel film deformation during solvent intake and drying. Film thickness profile measurements (near the drying line) for the aerogel, xerogel and pure solvent cases are presented from imaging ellipsometry. The thickness of these films (crack-free) were controlled in the range 0.1-3.5 {mu}m independent of refractive index.

Prakash, S.S. [New Mexico Univ., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States); Hurd, A.J. [Sandia National Labs., Albuquerque, NM (United States)

1994-12-31T23:59:59.000Z

392

Dry lubricant films for aluminum forming.  

DOE Green Energy (OSTI)

During metal forming process, lubricants are crucial to prevent direct contact, adhesion, transfer and scuffing of workpiece materials and tools. Boric acid films can be firmly adhered to the clean aluminum surfaces by spraying their methanol solutions and provide extremely low friction coefficient (about 0.04). The cohesion strengths of the bonded films vary with the types of aluminum alloys (6061, 6111 and 5754). The sheet metal forming tests indicate that boric acid films and the combined films of boric acid and mineral oil can create larger strains than the commercial liquid and solid lubricants, showing that they possess excellent lubricities for aluminum forming. SEM analyses indicate that boric acid dry films separate the workpiece and die materials, and prevent their direct contact and preserve their surface qualities. Since boric acid is non-toxic and easily removed by water, it can be expected that boric acid films are environmentally friendly, cost effective and very efficient lubricants for sheet aluminum cold forming.

Wei, J.; Erdemir, A.; Fenske, G. R.

1999-03-30T23:59:59.000Z

393

Exploding conducting film laser pumping apparatus  

DOE Patents (OSTI)

The 342-nm molecular iodine and the 1.315-..mu..m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.

Ware, K.D.; Jones, C.R.

1984-04-27T23:59:59.000Z

394

Process for fabrication of metal oxide films  

DOE Patents (OSTI)

This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

Tracy, C.E.; Benson, D.; Svensson, S.

1990-07-17T23:59:59.000Z

395

Electrochemical photovoltaic cell having ternary alloy film  

DOE Patents (OSTI)

A thin film compound semiconductor electrode comprising CdSe.sub.1-x Te.sub.x (0.ltoreq.x.ltoreq.1) is deposited on a transparent conductive substrate. An electrolyte contacts the film to form a photoactive site. The semiconductor material has a narrow energy bandgap permitting high efficiency for light conversion. The film may be fabricated by: (1) co-evaporation of two II-VI group compounds with a common cation, or (2) evaporation of three elements, concurrenty.

Russak, Michael A. (Farmingdale, NY)

1984-01-01T23:59:59.000Z

396

Method of producing amorphous thin films  

DOE Patents (OSTI)

Disclosed is a method of producing thin films by sintering which comprises: a. coating a substrate with a thin film of an inorganic glass forming parulate material possessing the capability of being sintered, and b. irridiating said thin film of said particulate material with a laser beam of sufficient power to cause sintering of said material below the temperature of liquidus thereof. Also disclosed is the article produced by the method claimed.

Brusasco, Raymond M. (Livermore, CA)

1992-01-01T23:59:59.000Z

397

Novel wide band gap materials for highly efficient thin film tandem solar cells  

SciTech Connect

Tandem solar cells (TSCs), which use two or more materials to absorb sunlight, have achieved power conversion efficiencies of >25% versus 11-20% for commercialized single junction solar cell modules. The key to widespread commercialization of TSCs is to develop the wide-band, top solar cell that is both cheap to fabricate and has a high open-circuit voltage (i.e. >1V). Previous work in TSCs has generally focused on using expensive processing techniques with slow growth rates resulting in costs that are two orders of magnitude too expensive to be used in conventional solar cell modules. The objective of the PLANT PV proposal was to investigate the feasibility of using Ag(In,Ga)Se2 (AIGS) as the wide-bandgap absorber in the top cell of a thin film tandem solar cell (TSC). Despite being studied by very few in the solar community, AIGS solar cells have achieved one of the highest open-circuit voltages within the chalcogenide material family with a Voc of 949mV when grown with an expensive processing technique (i.e. Molecular Beam Epitaxy). PLANT PV�s goal in Phase I of the DOE SBIR was to 1) develop the chemistry to grow AIGS thin films via solution processing techniques to reduce costs and 2) fabricate new device architectures with high open-circuit voltage to produce full tandem solar cells in Phase II. PLANT PV attempted to translate solution processing chemistries that were successful in producing >12% efficient Cu(In,Ga)Se2 solar cells by replacing copper compounds with silver. The main thrust of the research was to determine if it was possible to make high quality AIGS thin films using solution processing and to fully characterize the materials properties. PLANT PV developed several different types of silver compounds in an attempt to fabricate high quality thin films from solution. We found that silver compounds that were similar to the copper based system did not result in high quality thin films. PLANT PV was able to deposit AIGS thin films using a mixture of solution and physical vapor deposition processing, but these films lacked the p-type doping levels that are required to make decent solar cells. Over the course of the project PLANT PV was able to fabricate efficient CIGS solar cells (8.7%) but could not achieve equivalent performance using AIGS. During the nine-month grant PLANT PV set up a variety of thin film characterization tools (e.g. drive-level capacitance profiling) at the Molecular Foundry, a Department of Energy User Facility, that are now available to both industrial and academic researchers via the grant process. PLANT PV was also able to develop the back end processing of thin film solar cells at Lawrence Berkeley National Labs to achieve 8.7% efficient CIGS solar cells. This processing development will be applied to other types of thin film PV cells at the Lawrence Berkeley National Labs. While PLANT PV was able to study AIGS film growth and optoelectronic properties we concluded that AIGS produced using these methods would have a limited efficiency and would not be commercially feasible. PLANT PV did not apply for the Phase II of this grant.

Brian E. Hardin, Stephen T. Connor, Craig H. Peters

2012-06-11T23:59:59.000Z

398

Conductive layer for biaxially oriented semiconductor film ...  

... a photovoltaic cell, or a light emitting diode (LED) that includes a crystallographically oriented semiconducting film disposed on the conductive layer.

399

Characterization of Micro-, Nano-, and Thin Films  

Science Conference Proceedings (OSTI)

Feb 18, 2010... CdS:In Thin Films Prepared by the Spray-Pyrolysis Technique: Shadia Ikhmayies1; Riyad Ahmad-Bitar1; 1University of Jordan

400

Hierarchically Ordered Porous Carbon Films for Commercial ...  

Technology Marketing Summary Porous carbon films that can be optimized and assembled as electrodes in a device to desalinate water have been ...

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Enhanced Thin Film Organic Photovoltaic Devices  

A novel structure design for thin film organic photovoltaic (OPV) devices provides a system for increasing the optical absorption in the active layer. ...

402

Method of producing amorphous thin films  

DOE Patents (OSTI)

This invention dicloses a method for sintering particulate material (such as silica) with a laser beam to produce amorphous optical thin films on substrates.

Brusasco, R.M.

1991-12-31T23:59:59.000Z

403

Infrared Analysis of Advanced Thin Film Materials  

Science Conference Proceedings (OSTI)

The goals of timely and cost effective integration of these new materials into ... most widely accepted method for production monitoring of transparent thin films.

404

Available Technologies: Indium Phosphide Polycrystalline Films on ...  

Hot Electron Photovoltaics Using Low Cost Materials and Simple Design, IB-2195. Thinner Film Silicon Solar Cells, IB-2564. REFERENCE NUMBER: IB-3173, IB-3238.

405

Quick, Efficient Film Deposition for Nanomaterials - Energy ...  

Electricity Transmission; Energy Analysis; ... • Films can be deposited uniformly in a one-step deposition of nanoparticles with optimized drop distri ...

406

Hierarchically Ordered Porous Carbon Films for Commercial ...  

for kinetic adsorption. The ORNL invention offers both a method for making new, hierarchically ordered porous carbon films and describes a capacitive deionization

407

SPUTTERED THIN FILM PHOTOVOLTAICS - Home - Energy ...  

for photovoltaic (PV) applications .These processes result in films with better unif ormity over ... ultimately resulting in a more efficient solar ce ...

408

Magnetoresistance of alloy films and multilayers  

Science Conference Proceedings (OSTI)

The anisotropic magnetoresistance effect of alloy films and so-called giant magnetoresistance of superlattice multilayer films are reviewed. The usefulness for phenomenological explanation of both the anisotropic magnetoresistance and giant magnetoresistance of the two-current model, suggested first by Motto and subsequently extended by several researchers, is stressed. The relationship between the magnetoresistance and the magnetic anisotropy field is demonstrated for films exhibiting either anisotropic magnetoresistance or giant magnetoresistance. The magnetoresistances of multilayer films both with and without magnetic interaction between adjacent layers are compared. The dependence of the magnetoresistance on temperature is briefly discussed.

Miyazaki, T. (Tohoku Univ., Sendai (Japan))

1993-05-01T23:59:59.000Z

409

Understanding Protective Film Formation by Magnesium Alloys  

Science Conference Proceedings (OSTI)

Abstract Scope, Magnesium-based alloys are the lightest structural metals, and thus ... The present work aims to understand the mechanism(s) of protective film ...

410

and electrical properties of zinc oxide films  

E-Print Network (OSTI)

Undoped and indium-doped ZnO films have been deposited onto glass substrates by the spray pyrolysis method. The effect of indium incorporation on structural and electrical properties of ZnO films has been investigated. Zinc acetate dihydrate, indium chloride were used as a starting material and a dopant source, respectively. X-ray diffraction pattern of the films showed hexagonal wurtzite type polycrystalline structure. The results show that indium incorporation leads to substantial changes in the structural characteristics of ZnO films. The grain size was found to be in the range 15-50 nm, depending on indium content. In addition, the surface morphology features of the films, as a function of the indium content, are shown. For all the films, a linear dependence typical of ohmic behavior was observed. The electrical conductivity of ZnO films was improved by indium incorporation. The most important changes were observed for 1 at. % In-doped ZnO film which exhibit a resistivity of 3.2x10-1 ?cm. At certain constant voltage, from Arrhenius plots of In-doped ZnO films, activation energy values have been calculated from 17 meV to 89 meV.

unknown authors

2006-01-01T23:59:59.000Z

411

Polycrystalline Thin Film Solar Cell Technologies: Preprint  

DOE Green Energy (OSTI)

Rapid progress is being made by CdTe and CIGS-based thin-film PV technologies in entering commercial markets.

Ullal, H. S.

2008-12-01T23:59:59.000Z

412

Metal Current Collector Protected by Oxide Film  

For Industry; For Researchers; Success Stories; About Us; ... metal felt made substantially of inexpensive ferritic steel coated with a thin oxide film, ...

413

NIST Scientists Address 'Wrinkles' in Transparent Film ...  

Science Conference Proceedings (OSTI)

NIST Scientists Address 'Wrinkles' in Transparent Film Development. ... High on the wish list of the solar power industry is a cheap, flexible ...

2012-10-02T23:59:59.000Z

414

Mechanical Properties of Thin Film Metallic Glass  

Science Conference Proceedings (OSTI)

Because of these and other properties, thin film metallic-glasses (TFMGs) are a promising structural material for fabricating the next generation of micro- and ...

415

Textured Ultrafine Grained Al Thin Films  

Science Conference Proceedings (OSTI)

Symposium, Fatigue and Fracture of Thin Films and Nanomaterials. Presentation Title, In-Situ ACOM-TEM Nanomechanical Testing of Textured Ultrafine ...

416

Applied Films Corporation | Open Energy Information  

Open Energy Info (EERE)

Corporation Place Longmont, Colorado Zip 80504 Sector Services, Solar Product Provider of thin film deposition equipment and services, particularly to the solar industry....

417

Available Technologies: Thinner Film Silicon Solar Cells  

Berkeley Lab scientists have designed a new approach to create highly efficient thin film silicon solar cells. This technology promises to lower solar cell material ...

418

Thin Film Structures for Energy Efficient Systems  

Science Conference Proceedings (OSTI)

Thin film based energy generation and storage devices - Small scale ... Dye- sensitized Solar Cells with Anodized Aluminum Alloy-based Counter-electrodes.

419

Influence of copper to indium atomic ratio on the properties of Cu-In-Te based thin-film solar cells prepared by low-temperature co-evaporation  

SciTech Connect

The influence of copper to indium atomic ratio (Cu/In) on the properties of Cu-In-Te based thin films and solar cells was investigated. The films (Cu/In = 0.38-1.17) were grown on both bare and Mo-coated soda-lime glass substrates at 250 Degree-Sign C by single-step co-evaporation using a molecular beam epitaxy system. Highly (112)-oriented CuInTe{sub 2} films were obtained at Cu/In ratios of 0.84-0.99. However, stoichiometric and Cu-rich films showed a poor film structure with high surface roughness. The films consist of polyhedron-shaped grains, which are related to the coexistence of a Cu{sub 2-x}Te phase, and significant evidence for the coexistence of the Cu{sub 2-x}Te phase in the stoichiometric and Cu-rich films is presented. KCN treatment was performed for the films in order to remove the Cu{sub 2-x}Te phase. The stoichiometric CuInTe{sub 2} thin films exhibited a high mobility above 50 cm{sup 2}/V s at room temperature after the KCN treatment. A preliminary solar cell fabricated using a 1.4-{mu}m-thick Cu-poor CuInTe{sub 2} thin film (Cu/In = 0.84, E{sub g} = 0.988 eV) yielded a total-area efficiency of 2.10%. The photovoltaic performance of the cell was improved after long-term ambient aging in dark conditions.

Mise, Takahiro; Nakada, Tokio [Department of Electrical Engineering and Electronics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5258 (Japan)

2012-09-15T23:59:59.000Z

420

High-Tc Superconducting Thin- and Thick-Film-Based Coated Conductors for Energy Applications  

Science Conference Proceedings (OSTI)

Although the first epitaxial films of YBCO with high Tc were grown nearly 20 years ago, the understanding and control of the nanostructures responsible for the dissipation-free electrical current transport in high temperature superconductors (HTS) is quite recent. In the last six to seven years, major advances have occurred in the fundamental investigation of low angle grain boundaries, flux-pinning phenomena, growth mode, and atomic-level defect structures of HTS epitaxial films. As a consequence, it has been possible to map and even engineer to some extent the performance of HTS coatings in large regions of the operating H, T, J phase space. With such progress, the future of high temperature superconducting wires looks increasingly promising despite the tremendous challenges offered by these brittle and anisotropic materials. Nevertheless, further performance improvements are necessary for the superconducting technology to become cost-competitive against copper wires and ultimately succeed in revolutionizing the transmission of electricity. This can be achieved by further diminishing the gap between theoretical and experimental values of the critical current density Jc, and/or increasing the thickness of the superconductive layer as much as possible without degrading performance. In addition, further progress in controlling extrinsic and/or intrinsic nano-sized defects within the films is necessary to significantly reduce the anisotropic response of HTS and obtain a nearly constant dependence of the critical current on the magnetic field orientation, which is considered crucial for power applications. This chapter is a review of the challenges still present in the area of superconducting film processing for HTS wires and the approaches currently employed to address them.

Cantoni, Claudia [ORNL; Goyal, Amit [ORNL

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Dimethyl methylphosphonate Decomposition on fully Oxidized and Partially Reduced ceria Thin Films  

DOE Green Energy (OSTI)

The thermal decomposition of dimethyl methylphosphonate (DMMP) on crystalline ceria thin films grown on Ru(0 0 0 1) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and infrared absorption reflection spectroscopy (IRAS). TPD experiments show that methanol and formaldehyde desorb as the two main products at 575 K, while water, formaldehyde and CO are produced above 800 K. IRAS studies demonstrate that DMMP adsorbs via the phosphoryl oxygen at 200 K, but the P{double_bond}O bond converts to a bridging O{single_bond}P{single_bond}O species at 300 K. DMMP decomposition initially occurs via P{_}OCH{sub 3} bond scission to form methyl methylphosphonate (MMP) and methyl phosphonate (MP) between 300 and 500 K; XPS and IRAS data are consistent with a methoxy intermediate on the surface at these temperatures. The more stable P{_}CH{sub 3} bonds remain intact up to 700 K, and the only surface intermediate at higher temperatures is believed to be PO{sub x}. Although the presence of PO{sub x} decreases activity for DMMP decomposition, some activity on the ceria surface remains even after 7 cycles of adsorption and reaction. The ceria films become reduced by multiple DMMP adsorption-reaction cycles, with the Ce{sup +4} content dropping to 30% after seven cycles. Investigations of DMMP reaction on reduced ceria surfaces show that CO and H{sub 2} are produced in addition to methanol and formaldehyde. Furthermore, DMMP decomposition activity on the reduced ceria films is almost completely inhibited after only 3 adsorption-reaction cycles. Similarities between DMMP and methanol chemistry on the ceria films suggest that methoxy is a key surface intermediate in both reactions.

Chen, D.; Ratliff, J; Hu, X; Gordon, W; Senanayake, S; Mullins, D

2010-01-01T23:59:59.000Z

422

Thin-film optical initiator - Energy Innovation Portal  

A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film.

423

21L.011 The Film Experience, Fall 2006  

E-Print Network (OSTI)

An introduction to narrative film, emphasizing the unique properties of the movie house and the motion-picture camera, the historical evolution of the film medium, and the intrinsic artistic qualities of individual films. ...

Thorburn, David

424

Research on high-efficiency, single-junction, monolithic, thin-film amorphous silicon solar cells: Phase II annual subcontract report, 1 January 1985--31 January 1986  

DOE Green Energy (OSTI)

This report presents results of the second phase of research on high-efficiency, single-junction, monolithic, thin-film a-Si solar cells. Five glow-discharge deposition systems, including a new in-line, multichamber system, were used to grow both doped and undoped a-Si:H. A large number of silane and disilane gas cylinders were analyzed with a gas chromatography/mass spectroscopy system. Strong correlations were found between the breakdown voltage, the deposition rate, the diffusion length, and the conversion efficiency for varying cathode-anode separations in a DC glow-discharge deposition mode. Tin oxide films were grown by chemical vapor deposition with either tetramethyl tin (TMT) or tin tetrachloride (TTC). The best were grown with TMT, but TTC films had a more controlled texture for light trapping and provided a better contact to the p-layer. The best results were obtained with 7059 glass substrates. Efficiencies as high as 10.86% were obtained in p-i-n cells with superlattice p-layers and as high as 10.74% in cells with both superlattice p- and n-layers. Measurements showed that the boron-doping level in the p-layer can strongly affect transport in the i-layer, which can be minimized by reactive flushing before i-layer deposition. Stability of a-Si:H cells is improved by light doping. 51 refs., 64 figs., 21 tabs.

Carlson, D.E.; Ayra, R.R.; Bennett, M.S.; Catalano, A.; D'Aiello, R.V.; Dickson, C.R.; McVeigh, J.; Newton, J.; O'Dowd, J.; Oswald, R.S.; Rajan, K.

1988-09-01T23:59:59.000Z

425

Time resolved magneto-optical studies of ferromagnetic InMnSb films  

SciTech Connect

We report time resolved magneto-optical measurements in InMnSb ferromagnetic films with 2% and 2.8% Mn contents grown by low temperature molecular beam epitaxy. In order to probe a possible interaction between the spins of photoexcited carriers and the Mn ions, we measured spin dynamics before and after aligning the Mn ions by applying an external magnetic field at temperatures above and below the samples' Curie temperatures. We observed no significant temperature or magnetic field dependence in the relaxation times and attribute the observed dynamics entirely to the relaxation of photoexcited electrons in the conduction band where the s-d coupling with the localized Mn ions is significantly weaker compared to the p-d exchange coupling. We observed several differences in the optical response of our InMnSb samples which could have been influenced mainly by the samples' growth conditions.

Frazier, M.; Kini, R. N.; Nontapot, K.; Khodaparast, G. A. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Wojtowicz, T. [Institute of Physics, Polish Academy of Sciences 02-668 Warsaw (Poland); Liu, X.; Furdyna, J. K. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2008-02-11T23:59:59.000Z

426

The green manure value of seven clover species grown as annual crops on low and high fertility temperate soils.  

DOE Green Energy (OSTI)

Annual and perennial clover species may differ in green manure value. Seven clover (Trifolium) species were grown as annual crops on low fertility (Breton) and high fertility 15 (Edmonton) soils in Alberta

Ross, Shirley M.; King, Jane R.; Izaurralde, Roberto C.; O'Donovan, John T.

2009-05-01T23:59:59.000Z

427

Relation between crystallinity and chemical nature of surface on wettability: A study on pulsed laser deposited TiO{sub 2} thin films  

SciTech Connect

Pure titania (TiO{sub 2}) polycrystalline thin films in rutile, anatase and mixed phase have been grown on amorphous glass substrates by pulsed laser deposition method at various oxygen gas pressure. Wettability investigations have been carried out on these films. Consistent with our previous report [J. Phys. D: Appl. Phys. 41, 155308 (2008)] it has been observed that for nearly same surface roughness large contact angle or superhydrophobicity is present when sample has a pure single phase and lower contact angle or hydrophobicity when mixed phases were present. Structural characterizations suggest that in addition to roughness, pure phase film surface associated with hydrophobic sites and mixed phase film surface show association of both hydrophobic and hydrophilic sites, which might be inducing specific wetting character. UV treatment induces superhydrophilicity in the films. It was observed that UV irradiation causes nonequilibrium state on the TiO{sub 2} surface, leading to changes in the electron density, which in turn produces decrement in the crystallinity and lattice expansion. Reversible changes in the wetting state on the pure phase surfaces were observed to be faster than those on the mixed phase surfaces. We tried to establish the possible relation between crystalline phases, chemical nature of surface on reversible wettability besides the main governing parameter viz. surface roughness.

Shirolkar, Mandar M. [DST Unit on Nanoscience, Indian Institute of Science Education and Research, Pune, 411021 (India); Department of Physics, University of Pune, 411007 (India); Phase, Deodatta; Sathe, Vasant; Choudhary, Ram Janay [UGC-DAE Consortium for Scientific Research Indore Centre, Indore, 452017 (India); Rodriguez-Carvajal, J. [Laboratoire Leon Brillouin (CEA-CNRS), CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France); Kulkarni, Sulabha K. [DST Unit on Nanoscience, Indian Institute of Science Education and Research, Pune, 411021 India (India); Banasthali University, Banasthali, 304022 Rajasthan (India)

2011-06-15T23:59:59.000Z

428

Carbon Films Produced from Ionic Liquid Carbon Precursors ...  

The invention is directed to a method for producing a film of porous carbon, the method comprising carbonizing a film of an ionic liquid, wherein the ...

429

Institute of Photo Electronic Thin Film Devices and Technology...  

Open Energy Info (EERE)

Place Tianjin Municipality, China Zip 300071 Sector Solar Product A thin-film solar cell research institute in China. References Institute of Photo-Electronic Thin Film Devices...

430

Filming the crew at a meal in Japan  

E-Print Network (OSTI)

At the end of the filming in Japan, the team of film-makers and others have a celebration meal in a Japanese restaurant....

Macfarlane, Alan

2004-07-30T23:59:59.000Z

431

NREL: Photovoltaics Research - Polycrystalline Thin-Film Materials...  

NLE Websites -- All DOE Office Websites (Extended Search)

in the area of polycrystalline thin-film materials and devices. Printable Version Photovoltaics Research Home Silicon Polycrystalline Thin Films Multijunctions New Materials,...

432

Tungsten-doped thin film materials - Energy Innovation Portal  

A dielectric thin film material for high frequency use, including use as a capacitor, and having a low dielectric loss factor is provided, the film comprising a ...

433

Free film screening at Bradbury Science Museum September 7  

NLE Websites -- All DOE Office Websites (Extended Search)

Free Film Screening At Bradbury Science Museum Community Connections: Our link to Northern New Mexico Communities Latest Issue:Dec. 2013 - Jan. 2014 All Issues submit Free film...

434

Daylighting control performance of a thin-film ceramic electrochromic...  

NLE Websites -- All DOE Office Websites (Extended Search)

Daylighting control performance of a thin-film ceramic electrochromic window: Field study results Title Daylighting control performance of a thin-film ceramic electrochromic...

435

Breakthroughs in Thin-Film Magnetic Devices Earn NIST ...  

Science Conference Proceedings (OSTI)

... thin films to control magnetism as a foundation for developing better sensors and memory devices. Computer hard drives that use magnetic thin-film ...

2012-12-13T23:59:59.000Z

436

Amorphous and nanocrystalline Mg2Si thin-film electrodes  

NLE Websites -- All DOE Office Websites (Extended Search)

Contact Us Department Contacts Media Contacts Amorphous and nanocrystalline Mg2Si thin-film electrodes Title Amorphous and nanocrystalline Mg2Si thin-film electrodes...

437

Chemistry Chemical Analysis Thin-Films Information at NIST  

Science Conference Proceedings (OSTI)

... Method Can Affect the Use of Block Copolymer Thin Films (10/18 ... NIST Scientists Address 'Wrinkles' in Transparent Film Development (10/02/2012). ...

2010-09-24T23:59:59.000Z

438

Thin-Film/Low-K Dielectric Constant Measurement  

Science Conference Proceedings (OSTI)

... to pursue a very different approach to dielectric thin-film characterization at ... at NIST; DOW will simply deposit and pattern the thin films on pretested ...

2010-10-05T23:59:59.000Z

439

NIST Testing Method Quickly Tells Whether Thin Films Are ...  

Science Conference Proceedings (OSTI)

... and emerging technology areas that rely on thin-film advances for ... For films less than 1 micrometer thick, mechanical-property measurements made ...

2013-01-03T23:59:59.000Z

440

Thermoelectric effect in very thin film Pt/Au thermocouples  

E-Print Network (OSTI)

thin films, the electrical resistivity ratio ? F /? B is BStudies of the electrical resistivity of metallic films [23,calculate the electrical resistivity and the thermoelectric

Salvadori, M.C.; Vaz, A.R.; Teixeira, F.S.; Cattani, M.; Brown, I.G.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Improvement of Electrical Resistivity by Inserting the Graphene Film ...  

Science Conference Proceedings (OSTI)

Presentation Title, Improvement of Electrical Resistivity by Inserting the Graphene Film between Al doped ZnO Thin Films. Author(s), Jeong Do Yang, Dong-Hee ...

442

High-efficiency cadmium and zinc-telluride-based thin-film solar cells  

DOE Green Energy (OSTI)

This report describes research into polycrystalline CdTe solar cells grown by metal-organic chemical vapor deposition. Efficiencies of {approximately}10% were achieved using both p-i-n and p-n structures. A pre-heat treatment of CdS/SnO{sub 2}/glass substrates at 450{degrees}C in hydrogen atmosphere prior to the CdTe growth was found to be essential for high performance because this heat treatment reduces oxygen-related defects from the CdS surface. However, this treatment also resulted in a Cd-deficient CdS surface, which may in part limit the CdTe cell efficiency to 10% due to Cd vacancy-related interface defects. Preliminary model calculations suggest that removing these states can increase the cell efficiency from 10% to 13.5%. Photon absorption in the CdS film also limits the cell performance, and eliminating this loss mechanism can result in CdTe efficiencies in excess of 18%. Polycrystalline, 1.7-e, CdZnTe films were also grown for tandem-cell applications. CdZnTe/CdS cells processed using the standard CdTe cell fabrication procedure resulted in 4.4% efficiency, high series resistance, and a band-gap shift to 1.55 eV. The formation of Zn-O at and near the CdZnTe surface is the source of high contact resistance. A saturated dichromate each prior to contact deposition was found to solve the contact resistance problem. The CdCl{sub 2} treatment was identified as the cause of the observed band-gap shift due to the preferred formation of ZnCl{sub 2}. 59 refs.

Rohatgi, A.; Sudharsanan, R.; Ringel, S. (Georgia Inst. of Tech., Atlanta, GA (United States))

1992-02-01T23:59:59.000Z

443

Thin-Film Photovoltaic Industry  

Science Conference Proceedings (OSTI)

This report presents an overview of the thin-film (TF) photovoltaic (PV) industry as of the third quarter of 2012, a time in the midst of very rapid changes.  The TFPV industry has seen significantly greater investment in the past 5 to 10 years than in any previous time and up until recently it seemed that this investment was on track to make TFPV a much larger player in the overall PV market.  However, market dynamics have conspired to dim TFPV’s near-term prospects and ...

2012-11-30T23:59:59.000Z

444

Thin film solar energy collector  

DOE Patents (OSTI)

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

Aykan, Kamran (Monmouth Beach, NJ); Farrauto, Robert J. (Westfield, NJ); Jefferson, Clinton F. (Millburn, NJ); Lanam, Richard D. (Westfield, NJ)

1983-11-22T23:59:59.000Z

445

Meteorological Twin–Hot-Film Anemometry  

Science Conference Proceedings (OSTI)

A dual-sensor, twin–hot-film anemometer is applied to meteorological measurement of wind velocity in fair and rainy weather. Two sensors, each with a pair of hot-films mounted side by side, were operated in constant-temperature mode and ...

Brian E. Thompson; Robert C. Hassman Jr.

2001-04-01T23:59:59.000Z

446

Measuring droplet impact with piezoelectric film  

E-Print Network (OSTI)

The objective of this research was to develop a measurement system for determining droplet impact in the field with piezoelectric film. The piezoelectric film generates an output signal when it is deformed. The signals are analyzed with a data acquisition system (a computer with two high speed boards). Eight piezoelectric films were calibrated in the laboratory. Each film was calibrated by releasing various water droplet sizes from different heights. The signal output of film was then related to the kinetic energy of the droplet. The maximum droplet diameter generated was 5.6 mm, and the maximum height used was 4.59 m. To simulate a kinetic energy for larger droplets and higher elevations, a solid particle with 9.9 mm diameter and 0.5 gram mass was used. The results show that, in general, the output of piezoelectfic film responds linearly to kinetic energy. However, due to the size of the film used and deformation of large droplets upon impact, the output become non-linear and may be represented by Y=ax1 +bx2 +cx1cx2+dx12x2+ex13x2 + where, y = sensor output a, b, c, d, e = constants which depend on the characteristics of the film X1 = the kinetic energy X2 = I for the solid particle X2= 0 for water drops The measurement system was tested in the field. The results showed that this system could be used to measure droplet impact force at different places on plants.

Basahi, Jalal M. Al-Badry M.

1993-01-01T23:59:59.000Z

447

A replaceable reflective film for solar concentrators  

DOE Green Energy (OSTI)

The 3M Company manufactures a silvered acrylic film called ECP-305 that is regarded as the preferred reflective film for use on stretched-membrane heliostats. However, ECP-305 will degrade in time, due to both corrosion of the silver layer and delamination at the film's silver-to-acrylic interface, and will eventually need to be replaced. 3M uses a very aggressive adhesive on this film, and once it is laminated, replacement is very difficult. The purpose of this investigation was the development of a replaceable reflector, a reflective film that can be easily removed and replaced. A replaceable reflector was successfully configured by laminating ECP-305 to the top surface of a smooth, dimensionally stable polymer film, with a removable adhesive applied to the underside of the polymer film. Several stages of screening and testing led to the selection of a 0.010-inch thick polycarbonate (GE 8030) as the best polymer film and a medium tack tape (3M Y-9425) was selected as the best removable adhesive. To demonstrate the feasibility of the replaceable reflector concept and to provide a real-time field test, the chosen construction was successfully applied to the 50-m{sup 2} SKI heliostat at the Central Receiver Test Facility at Sandia National Laboratories in Albuquerque. 4 refs., 13 figs., 7 tabs.

Not Available

1991-09-01T23:59:59.000Z

448

Thin films of mixed metal compounds  

DOE Patents (OSTI)

A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.

Mickelsen, Reid A. (Bellevue, WA); Chen, Wen S. (Seattle, WA)

1985-01-01T23:59:59.000Z

449

Organic conductive films for semiconductor electrodes  

DOE Patents (OSTI)

According to the present invention, improved electrodes overcoated with conductive polymer films and preselected catalysts are provided. The electrodes typically comprise an inorganic semiconductor overcoated with a charge conductive polymer film comprising a charge conductive polymer in or on which is a catalyst or charge-relaying agent.

Frank, Arthur J. (Lakewood, CO)

1984-01-01T23:59:59.000Z

450

Preparation of a semiconductor thin film  

SciTech Connect

A process for the preparation of a semiconductor film. The process comprises depositing nanoparticles of a semiconductor material onto a substrate whose surface temperature during nanoparticle deposition thereon is sufficient to cause substantially simultaneous fusion of the nanoparticles to thereby coalesce with each other and effectuate film growth.

Pehnt, Martin (TuBingen, DE); Schulz, Douglas L. (Denver, CO); Curtis, Calvin J. (Lakewood, CO); Ginley, David S. (Evergreen, CO)

1998-01-01T23:59:59.000Z

451

Characterization of photoluminescent (Y{sub 1{minus}x}Eu{sub x}){sub 2}O{sub 3} thin-films prepared by metallorganic chemical vapor deposition  

SciTech Connect

Europium doped yttrium oxide, (Y{sub 1{minus}x}Eu{sub x}){sub 2}O{sub 3}, thin-films were deposited on silicon and sapphire substrates by metallorganic chemical vapor deposition (MOCVD). The films were grown in a MOCVD chamber reacting yttrium and europium tris(2,2,6,6-tetramethyl-3,5,-heptanedionates) precursors in an oxygen atmosphere at low pressures (5 Torr) and low substrate temperatures (500--700 C). The films deposited at 500 C were flat and composed of nanocrystalline regions of cubic Y{sub 2}O{sub 3}, grown in a textured [100] or [110] orientation to the substrate surface. Films deposited at 600 C developed from the flat, nanocrystalline morphology into a plate-like growth morphology oriented in the [111] with increasing deposition time. Monoclinic Y{sub 2}O{sub 3}:Eu{sup 3+} was observed in x-ray diffraction for deposition temperatures {ge}600 C on both (111) Si and (001) sapphire substrates. This was also confirmed by the photoluminescent emission spectra.

McKittrick, J.; Bacalski, C.F.; Hirata, G.A. [Univ. of California, San Diego, La Jolla, CA (United States); Hubbard, K.M.; Pattillo, S.G.; Salazar, K.V.; Trkula, M. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

1998-12-01T23:59:59.000Z

452

Site-controlled Ag nanocrystals grown by molecular beam epitaxy-Towards plasmonic integration technology  

Science Conference Proceedings (OSTI)

We demonstrate site-controlled growth of epitaxial Ag nanocrystals on patterned GaAs substrates by molecular beam epitaxy with high degree of long-range uniformity. The alignment is based on lithographically defined holes in which position controlled InAs quantum dots are grown. The Ag nanocrystals self-align preferentially on top of the InAs quantum dots. No such ordering is observed in the absence of InAs quantum dots, proving that the ordering is strain-driven. The presented technique facilitates the placement of active plasmonic nanostructures at arbitrarily defined positions enabling their integration into complex devices and plasmonic circuits.

Urbanczyk, Adam [COBRA Research Institute on Communication Technology, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Noetzel, Richard [Institute for Systems based on Optoelectronics and Microtechnology (ISOM), ETSI Telecommunication, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2012-12-15T23:59:59.000Z

453

Blue Emission Peak of GeO{sub 2} Particles Grown Using Thermal Evaporation  

Science Conference Proceedings (OSTI)

In this paper we report a simple thermal evaporation technique (horizontal tube furnace) to grow large quantities of GeO{sub 2} particles with diameters ranging from tens of nanometer to 500 nm on n-type (100) Si substrate free of catalyst. The particles were grown at temperature about 1000 degree sign C for 2 hrs and characterized by scanning electron microscopy (SEM), X-Ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and photoluminescence (PL) spectroscopy. The photoluminescence spectrum reveals several emission peaks around 400 nm at room temperature. Raman measurement also measured at room temperature for this GeO{sub 2} particles.

Sulieman, Kamal Mahir [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang (Malaysia); Physics Department, Alzaiem Alazhary University, 1432-Khartoum (Sudan); Jumidali, M. M. [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang (Malaysia); Faculty of Applied Science, Universiti Teknologi MARA, 13500 Penang (Malaysia); Hashim, M. R. [School of Physics, Universiti Sains Malaysia (USM), 11800 Minden, Penang (Malaysia)

2010-07-07T23:59:59.000Z

454

Confinement in PbSe wires grown by rf magnetron sputtering  

SciTech Connect

Lead selenide (PbSe) nanowires were grown by magnetron sputtering on silicon with silicon dioxide (SiO{sub 2}/Si) substrates, and characterized by scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence, and x-ray photoelectron spectroscopy. Closely packed PbSe nanowires of approximately 100 nm diameter grew in the <111> rock-salt cubic structure orientation. These large wires showed a large blueshift in the luminescence and absorption compared to the bulk crystal, demonstrating quantum confinement. This is attributed to a strong built-in field due to surface states, band bending, and a depletion layer which confines the carrier states.

Jung, Hyeson; Kuljic, Rade [Department of Electrical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Stroscio, Michael A. [Department of Electrical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Dutta, Mitra [Department of Electrical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States)

2010-04-12T23:59:59.000Z

455

Human Radiation Experiments: Multimedia: Film Clips  

NLE Websites -- All DOE Office Websites (Extended Search)

Film Clips Multimedia Film Clips Multimedia Home Roadmap What's New Multimedia Related Sites Feedback Sound Bytes Film Clips Historical Photographs Films require: Get Real Player 5.0 to view the films on this page. The Atom and You Second in the series The Atom and You, Paramount News, March 25, 1953, shows tests conducted at Hanford, Washington, on effects of exposure of sheep and salmon to radiation; testing of radioactive dust at UCLA laboratory; the use of radioisotopes and tracer materials for detecting cancer in patients at Oak Ridge, Tennessee; the use of rays from the cobalt source at N.Y. cityÂ’s Moncure Hospital, to treat cancer of the brain. (Time: 5 min 9 secs) Real Media Download Versions 28.8 kbps version (782k) 56.0 kbps version (1.3mb) T1 version (7.5mb) Iodine 131

456

Selective Plasmonic Gas Sensing: H2, NO2, and CO Discrimination by a Single Au-CeO2 Nanocomposite Film  

Science Conference Proceedings (OSTI)

A Au-CeO2 nanocomposite film has been investigated as a potential sensing element for high-temperature plasmonic sensing of H2, CO, and NO2 in an oxygen containing environment. The CeO2 thin film was deposited by molecular beam epitaxy (MBE) and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. The Au-CeO2 nanocomposite film was characterized by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H2, CO, and NO2 were performed at a temperature of 500 C in oxygen backgrounds of 5.0, 10, and {approx}21% O2. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation-reduction processes that fill or create oxygen vacancies in the CeO2. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles or by changes in the dielectric constant surrounding the particles. Multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. From principal component analysis (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant analysis (LDA) was also used and showed separation between analytes as well as trends in gas concentration. Results indicate that the Au-CeO2 thin film is selective to O2, H2, CO, and NO2 in separate exposures. Combined with the observed stability over long exposure periods, the Au-CeO2 film shows good potential as an optical sensing element for harsh environmental conditions.

Joy, N.; Nandasiri, Manjula I.; Rogers, Phillip H.; Jiang, Weilin; Varga, Tamas; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai; Carpenter, Michael A.

2012-06-05T23:59:59.000Z

457