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1

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

SciTech Connect (OSTI)

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

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

2012-06-05T23:59:59.000Z

2

Observation of photoluminescence from Al1 xInxN heteroepitaxial films grown by metalorganic vapor phase epitaxy  

E-Print Network [OSTI]

Observation of photoluminescence from Al1 xInxN heteroepitaxial films grown by metalorganic vapor have observed photoluminescence of Al1 xInxN films. The films were grown on GaN by atmospheric pressure-temperature deposited AlN buffer layer. Photoluminescence, absorption, and x-ray diffraction measurements have shown

Wetzel, Christian M.

3

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

SciTech Connect (OSTI)

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

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

2007-08-15T23:59:59.000Z

4

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

SciTech Connect (OSTI)

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

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

2014-09-01T23:59:59.000Z

5

Selective etching of dislocations in GaN grown by low-pressure solution growth  

Science Journals Connector (OSTI)

This work presents an experimental study on the identification and quantification of different types of dislocations in GaN grown by low-pressure solution growth. A reliable defect selective etching procedure in a NaOH-KOH melt is developed and validated using transmission electron microscopy that permits to define groups of etch pits that belong each to dislocations with a specific Burgers vector. This way a comparably fast method is provided for determining the total, the specific dislocation densities and the type of dislocation in a statistically representative way. The results for the solution grown samples are compared to those obtained for MOCVD GaN.

I.Y. Knoke; P. Berwian; E. Meissner; J. Friedrich; H.P. Strunk; G. Müller

2010-01-01T23:59:59.000Z

6

Journal of Crystal Growth 293 (2006) 273277 A study of semi-insulating GaN grown on AlN buffer/sapphire  

E-Print Network [OSTI]

-temperature GaN interlayer. In comparison with the normal GaN grown on sapphire, the crystal quality measurement results of GaN grown directly on an AlN buffer indicated that the as-grown-undoped Ga, or high density of edge-type dislocations [6­10]. However, Fe and other heavy metals tend to have reactor

Ozbay, Ekmel

7

Green light emitting diode grown on thick strain-reduced GaN template  

Science Journals Connector (OSTI)

Abstract We report a green light-emitting diode (LED) grown on thick strain-reduced GaN template. As the injection current changes from 20 mA to 120 mA, blue-shift of EL peak wavelength reduces from 9.3 nm for the LED on sapphire substrate to 6.8 nm for the LED grown on thick strain-reduced GaN template. Furthermore, the light output power and external quantum efficiency of the LED on thick strain-reduced GaN template are respectively 1.48 mW and 2.5% at the forward current of 20 mA, which is twice as much as the LED on sapphire substrate. In contrast, the reverse current is 2 ?A lower than that of the LED on the sapphire at ?8 V.

Jiankun Yang; Tongbo Wei; Qiang Hu; Ziqiang Huo; Baojuan Sun; Ruifei Duan; Junxi Wang

2015-01-01T23:59:59.000Z

8

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

SciTech Connect (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 (<0.09 {Omega} mm) were obtained, with a minimum R{sub C} of 0.035 {Omega} mm on a sample with a room temperature carrier concentration of {approx}5 Multiplication-Sign 10{sup 19} cm{sup -3}. Based on the systematic study, the role of R{sub C} and R{sub sh} is discussed in the context of regrown n{sup +} GaN ohmic contacts for GaN based high electron mobility transistors.

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

9

Conductivity of Oriented Samaria-Doped Ceria Thin Films Grown...  

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

Conductivity of Oriented Samaria-Doped Ceria Thin Films Grown by Oxygen-plasma-assisted Molecular Beam Epitaxy. Conductivity of Oriented Samaria-Doped Ceria Thin Films Grown by...

10

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

E-Print Network [OSTI]

A Comparison of Magnesium and Beryllium Acceptors in GaN Grown by rf-Plasma Assisted Molecular Beam Evans and Associates, Sunnyvale, CA 94086 ABSTRACT Step-doped structures of both magnesium and beryllium activation energy of approximately 100 meV. INTRODUCTION While magnesium is currently the most

Myers, Tom

11

Thermal annealing characteristics of Si and Mg-implanted GaN thin films  

SciTech Connect (OSTI)

In this letter, we report the results of ion implantation of GaN using {sup 28}Si and {sup 24}Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 40 keV 10{sup 14} cm{sup {minus}2} Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690{degree}C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties. {copyright} {ital 1996 American Institute of Physics.}

Chan, J.S.; Cheung, N.W. [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)] [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Schloss, L.; Jones, E.; Wong, W.S.; Newman, N.; Liu, X.; Weber, E.R. [Department of Material Science and Mineral Engineering, University of California, Berkeley, California 64720 (United States)] [Department of Material Science and Mineral Engineering, University of California, Berkeley, California 64720 (United States); Gassman, A.; Rubin, M.D. [Lawrence Berkeley Laboratory, 1 Cyclotron Road, University of California, Berkeley, California 64720 (United States)] [Lawrence Berkeley Laboratory, 1 Cyclotron Road, University of California, Berkeley, California 64720 (United States)

1996-05-01T23:59:59.000Z

12

Hydrothermally grown nanostructured WO films and their electrochromic characteristics  

E-Print Network [OSTI]

Hydrothermally grown nanostructured WO 3 films and their electrochromic characteristics.1088/0022-3727/43/28/285501 Hydrothermally grown nanostructured WO3 films and their electrochromic characteristics Zhihui Jiao1 , Xiao Wei and their electrochromic characteristics. Plate-like monoclinic WO3 nanostructures were grown directly on fluorine

Demir, Hilmi Volkan

13

Group III-nitride thin films grown using MBE and bismuth  

DOE Patents [OSTI]

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

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

2000-01-01T23:59:59.000Z

14

Group III-nitride thin films grown using MBE and bismuth  

DOE Patents [OSTI]

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

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

2002-01-01T23:59:59.000Z

15

Partially filled intermediate band of Cr-doped GaN films  

SciTech Connect (OSTI)

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

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

2012-05-14T23:59:59.000Z

16

GaN nanorod light emitting diodes with suspended graphene transparent electrodes grown by rapid chemical vapor deposition  

SciTech Connect (OSTI)

Ordered and dense GaN light emitting nanorods are studied with polycrystalline graphene grown by rapid chemical vapor deposition as suspended transparent electrodes. As the substitute of indium tin oxide, the graphene avoids complex processing to fill up the gaps between nanorods and subsequent surface flattening and offers high conductivity to improve the carrier injection. The as-fabricated devices have 32% improvement in light output power compared to conventional planar GaN-graphene diodes. The suspended graphene remains electrically stable up to 300?°C in air. The graphene can be obtained at low cost and high efficiency, indicating its high potential in future applications.

Xu, Kun; Xu, Chen, E-mail: xuchen58@bjut.edu.cn; Deng, Jun; Zhu, Yanxu; Guo, Weiling; Mao, Mingming; Xun, Meng; Chen, Maoxing; Zheng, Lei [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China)] [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China); Xie, Yiyang [State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductor, Chinese Academy of Sciences, Beijing 100083 (China)] [State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductor, Chinese Academy of Sciences, Beijing 100083 (China); Sun, Jie, E-mail: jie.sun@chalmers.se [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China) [Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Ministry of Education, Beijing 100124 (China); Mikroteknologi och Nanovetenskap, Chalmers Tekniska Högskola AB, Göteborg 41296 (Sweden)

2013-11-25T23:59:59.000Z

17

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

SciTech Connect (OSTI)

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

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

2013-10-14T23:59:59.000Z

18

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

SciTech Connect (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

19

X-ray determination of threading dislocation densities in GaN/Al{sub 2}O{sub 3}(0001) films grown by metalorganic vapor phase epitaxy  

SciTech Connect (OSTI)

Densities of a- and a+c-type threading dislocations for a series of GaN films grown in different modes by metalorganic vapor phase epitaxy are determined from the x-ray diffraction profiles in skew geometry. The reciprocal space maps are also studied. Theory of x-ray scattering from crystals with dislocations is extended in order to take into account contribution from both threading and misfit dislocations. The broadening of the reciprocal space maps along the surface normal and the rotation of the intensity distribution ellipse is attributed to misfit dislocations at the interface. We find that the presence of a sharp AlN/GaN interface leads to an ordering of misfit dislocations and reduces strain inhomogeneity in GaN films.

Kopp, Viktor S., E-mail: victor.kopp@pdi-berlin.de; Kaganer, Vladimir M. [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Baidakova, Marina V.; Lundin, Wsevolod V.; Nikolaev, Andrey E.; Verkhovtceva, Elena V.; Yagovkina, Maria A. [Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Politekhnicheskaya 26, 194021 St.-Petersburg (Russian Federation); Cherkashin, Nikolay [CEMES-CNRS and Université de Toulouse, 29 rue J. Marvig, 31055 Toulouse (France)

2014-02-21T23:59:59.000Z

20

Annealing of the radiation damage in Mg-implanted GaN thin films: Temperature development of lattice parameters and stresses  

Science Journals Connector (OSTI)

Heteroepitaxial GaN thin films implanted with Mg ions with a concentration of 1.3 × 1019 cm?3 are analyzed using in-situ X-ray diffraction in the temperature range of 20–700 °C. The temperature dependence of unstressed lattice parameters and stresses in the implanted films is evaluated and compared with the results from a virgin GaN thin film. The measurements indicate that the annealing of the radiation damage in the implanted GaN is accompanied by a unique temperature hysteresis of the GaN structural characteristics and the main part of the radiation damage is removed during heating in the temperature range of 100–300 °C. The temperature of 1620 °C is extrapolated as an important annealing limit in order to significantly decrease implantation-induced disorder in the films.

J. Keckes; A. Wenzel; J.W. Gerlach; B. Rauschenbach

2003-01-01T23:59:59.000Z

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.


21

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

E-Print Network [OSTI]

results in the task of bipolar doping of intermediate and wide band-gap materials like CdS,1­3 ZnSe,4 ZnPHYSICAL REVIEW B 86, 075207 (2012) Optical signature of Mg-doped GaN: Transfer processes G; published 23 August 2012) Mg doping of high quality, metal organic chemical vapor deposition grown GaN films

Nabben, Reinhard

22

Thin crystalline silicon solar cells based on epitaxial films grown at 165C by RF PECVD  

E-Print Network [OSTI]

1 Thin crystalline silicon solar cells based on epitaxial films grown at 165°C by RF PECVD Romain temperatures. Keywords : Low temperature, epitaxy, PECVD, Si thin film, Solar cell hal-00749873,version1-25Nov shortage until 2010. Research on epitaxial growth for thin film crystalline silicon solar cells has gained

23

Dependence of the Mg-related acceptor ionization energy with the acceptor concentration in p-type GaN layers grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Hall effect and capacitance-voltage C(V) measurements were performed on p-type GaN:Mg layers grown on GaN templates by molecular beam epitaxy with a high range of Mg-doping concentrations. The free hole density and the effective dopant concentration N{sub A}-N{sub D} as a function of magnesium incorporation measured by secondary ion mass spectroscopy clearly reveal both a magnesium doping efficiency up to 90% and a strong dependence of the acceptor ionization energy Ea with the acceptor concentration N{sub A}. These experimental observations highlight an isolated acceptor binding energy of 245{+-}25 meV compatible, at high acceptor concentration, with the achievement of p-type GaN:Mg layers with a hole concentration at room temperature close to 10{sup 19} cm{sup -3}.

Brochen, Stephane; Brault, Julien; Chenot, Sebastien; Dussaigne, Amelie; Leroux, Mathieu; Damilano, Benjamin [CNRS-CRHEA, Rue Bernard Gregory, F-06560 Valbonne (France)

2013-07-15T23:59:59.000Z

24

Piezo-Phototronic Effect on Electroluminescence Properties of p-Type GaN Thin Films  

E-Print Network [OSTI]

significance on the practical applications of GaN in optoelectronic devices under a working environment where,9 Recent studies have shown its applications in improving the performance of optoelectronic devices based result in great influence for this most popular III-V semiconductor used in optoelectronic devices

Wang, Zhong L.

25

Optimization of High Tunability Barium Strontium Titanate Thin Films Grown by RF Magnetron  

E-Print Network [OSTI]

Optimization of High Tunability Barium Strontium Titanate Thin Films Grown by RF Magnetron Abstract-- Barium strontium titanate is a solid solution perovskite with a field-dependent permittivity.7 MV/cm. I. INTRODUCTION In recent years there has been much interest in thin-film barium strontium

York, Robert A.

26

Thin crystalline silicon solar cells based on epitaxial films grown at 165C by RF PECVD  

E-Print Network [OSTI]

1 Thin crystalline silicon solar cells based on epitaxial films grown at 165°C by RF PECVD Romain temperatures. Keywords : Low temperature, epitaxy, PECVD, Si thin film, Solar cell #12;2 1. Introduction: martin.labrune@polytechnique.edu ABSTRACT We report on heterojunction solar cells whose thin intrinsic

27

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

E-Print Network [OSTI]

. 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...

Ganapathy Subramanian, Santhana

2004-09-30T23:59:59.000Z

28

Magnesium outdiffusion through magnetite films grown on magnesium oxide (001) (abstract)  

E-Print Network [OSTI]

Magnesium outdiffusion through magnetite films grown on magnesium oxide (001) (abstract) K. A. Shaw of magnesium in the uppermost layers of the film, and indicate a concentration gradient, with the highest concentrations of magnesium in the surface layer. X-ray fluorescence in scanning electron microscopy

Diebold, Ulrike

29

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

SciTech Connect (OSTI)

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

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

2013-12-02T23:59:59.000Z

30

Do CVD grown graphene films have antibacterial activity on metallic substrates?  

E-Print Network [OSTI]

Accurate assessment of the antibacterial activity of graphene requires consideration of both the graphene fabrication method and, for supported films, the properties of the substrate. Large-area graphene films produced by chemical vapor deposition were grown directly on copper substrates or transferred on a gold substrate and their effect on the viability and proliferation of the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli were assessed. The viability and the proliferation of both bacterial species were not affected when they were grown on a graphene film entirely covering the gold substrate, indicating that conductivity plays no role on bacterial viability and graphene has no antibacterial activity against S. aureus and E. coli. On the other hand, antibacterial activity was observed when graphene coated the copper substrates, resulting from the release of bactericidal cupric ions in inverse proportion to the graphene surface coverage.

Dellieu, Louis; Reckinger, Nicolas; Didembourg, Christian; Letesson, Jean-Jacques; Sarrazin, Michael; Deparis, Olivier; Matroule, Jean-Yves; Colomer, Jean-François

2014-01-01T23:59:59.000Z

31

Non-destructive characterization of films grown on Zircaloy-2 by annealing in air  

Science Journals Connector (OSTI)

Zircaloy-2 is often used in engineering applications because of its corrosion resistance; a property attributable to a protective oxide film that grows on its surface. Variable angle infrared (IR) reflection spectroscopy and atomic force microscopy are used to determine the thickness and roughness of such films grown thermally on Zircaloy-2 surfaces in air. We find cubic growth kinetics in the temperature range 500-600°C with an apparent activation energy of 227 kJ mol-1. We also demonstrate how an increase in microscopic surface roughness at higher temperatures correlates with a loss of oxide homogeneity as sampled by the IR method.

J S McNatt; M J Shepard; N Farkas; J M Morgan; R D Ramsier

2002-01-01T23:59:59.000Z

32

Elastic properties of B-C-N films grown by N{sub 2}-reactive sputtering from boron carbide targets  

SciTech Connect (OSTI)

Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B{sub 4}C target and N{sub 2} as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions.

Salas, E.; Jiménez Riobóo, R. J.; Jiménez-Villacorta, F.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain)] [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain); Sánchez-Marcos, J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain) [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid (Spain); Dept. Química-Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Muñoz-Martín, A.; Prieto, J. E.; Joco, V. [Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)] [Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

2013-12-07T23:59:59.000Z

33

Interference effects in photoreflectance and contactless electroreflectance spectra of CdTe films grown on Si substrate  

E-Print Network [OSTI]

Interference effects in photoreflectance and contactless electroreflectance spectra of CdTe films and contactless electroreflectance CER spectra of CdTe films grown on Si substrate, at energies below the band gap of CdTe. The simultaneous observation of OF in the reflectance (R) spectrum having the same period

Ghosh, Sandip

34

Unexpected behaviour of one Pb monolayer deposited on aluminum oxide thin film grown on Ag(111)  

SciTech Connect (OSTI)

Using scanning tunneling microscopy (STM), Auger electron spectroscopy, and low energy electron diffraction, we have observed a surprising complete dissolution at room temperature of one lead monolayer deposited by evaporation on an aluminum oxide thin film (?0.8?nm thick) previously grown on Ag (111). We have observed the quasi-instantaneous diffusion of the lead deposit through the oxide layer to the silver/oxide interface. After the diffusion process, lead atoms form a Moiré superstructure, which is characterized by STM through the oxide layer. This unexpected behavior puts in light the very weak interaction between the aluminum oxide and the silver substrate.

Vizzini, Sébastien, E-mail: sebastien.vizzini@im2np.fr; Bertoglio, M. [IM2NP CNRS, Aix Marseille Université, F-13397 Marseille (France)] [IM2NP CNRS, Aix Marseille Université, F-13397 Marseille (France); Oughaddou, Hamid [Institut des Sciences Moléculaires d'Orsay, ISMO CNRS, Université de Paris, F-91405 Orsay, France and Deptartamento de Physique, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise (France)] [Institut des Sciences Moléculaires d'Orsay, ISMO CNRS, Université de Paris, F-91405 Orsay, France and Deptartamento de Physique, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise (France); Hoarau, J. Y.; Biberian, J. P.; Aufray, B. [CINaM CNRS, Aix Marseille Université, F-13288 Marseille (France)] [CINaM CNRS, Aix Marseille Université, F-13288 Marseille (France)

2013-12-23T23:59:59.000Z

35

Photoluminescence from GaN layers at high temperatures as a candidate for in situ monitoring in MOVPE  

Science Journals Connector (OSTI)

Abstract Efficient photoluminescence (PL) spectra from GaN and InGaN layers at temperatures up to 1100 K are observed with low noise floor and high dynamic resolution. A number of detailed spectral features in the PL can be directly linked to physical properties of the epitaxial grown layer. The method is suggested as an in situ monitoring tool during epitaxy of nitride LED and laser structures. Layer properties like thickness, band gap or film temperature distribution are feasible.

C. Prall; M. Ruebesam; C. Weber; M. Reufer; D. Rueter

2014-01-01T23:59:59.000Z

36

Resistance of Thin Metal Films Grown under a Longitudinal Electric Field  

Science Journals Connector (OSTI)

Thin?film samples of platinum silver and gold were prepared in pairs on glass substrates by evaporation in a vacuum of 10?6?10?7 Torr one sample of the pair under an electric field (usually 40 V/cm either dc or 500?Hz square wave) applied along the substrate surface and the other sample under no field. Sample resistances were measured in the vacuum at temperatures ranging from roughly 0 °C to 4 °K. The resistances of the samples deposited under a field were almost invariably lower sometimes by orders of magnitude than those of the corresponding samples grown under no field. Electron micrographs show that the former samples had elongated and interconnected grains while the latter samples had roundish and more islolated grains. The data are discussed in terms of a simple model based on the notion that the film particles polarize stretch and even coalesce under the applied electric field before they solidify.

E. Ahilea; A. A. Hirsch

1971-01-01T23:59:59.000Z

37

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

SciTech Connect (OSTI)

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

38

Induced polarized state in intentionally grown oxygen deficient KTaO{sub 3} thin films  

SciTech Connect (OSTI)

Deliberately oxygen deficient potassium tantalate thin films were grown by RF magnetron sputtering on Si/SiO{sub 2}/Ti/Pt substrates. Once they were structurally characterized, the effect of oxygen vacancies on their electric properties was addressed by measuring leakage currents, dielectric constant, electric polarization, and thermally stimulated depolarization currents. By using K{sub 2}O rich KTaO{sub 3} targets and specific deposition conditions, KTaO{sub 3-{delta}} oxygen deficient thin films with a K/Ta = 1 ratio were obtained. Room temperature X-ray diffraction patterns show that KTaO{sub 3-{delta}} thin films are under a compressive strain of 2.3% relative to KTaO{sub 3} crystals. Leakage current results reveal the presence of a conductive mechanism, following the Poole-Frenkel formalism. Furthermore, dielectric, polarization, and depolarization current measurements yield the existence of a polarized state below T{sub pol} {approx} 367 Degree-Sign C. A Cole-Cole dipolar relaxation was also ascertained apparently due to oxygen vacancies induced dipoles. After thermal annealing the films in an oxygen atmosphere at a temperature above T{sub pol}, the aforementioned polarized state is suppressed, associated with a drastic oxygen vacancies reduction emerging from annealing process.

Mota, D. A.; Romaguera-Barcelay, Y.; Tkach, A.; Agostinho Moreira, J.; Almeida, A. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science of University of Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Perez de la Cruz, J. [INESC TEC, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Vilarinho, P. M. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Tavares, P. B. [Centro de Quimica, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal)

2013-07-21T23:59:59.000Z

39

Nanostructural engineering of nitride nucleation layers for GaN substrate dislocation reduction.  

SciTech Connect (OSTI)

With no lattice matched substrate available, sapphire continues as the substrate of choice for GaN growth, because of its reasonable cost and the extensive prior experience using it as a substrate for GaN. Surprisingly, the high dislocation density does not appear to limit UV and blue LED light intensity. However, dislocations may limit green LED light intensity and LED lifetime, especially as LEDs are pushed to higher current density for high end solid state lighting sources. To improve the performance for these higher current density LEDs, simple growth-enabled reductions in dislocation density would be highly prized. GaN nucleation layers (NLs) are not commonly thought of as an application of nano-structural engineering; yet, these layers evolve during the growth process to produce self-assembled, nanometer-scale structures. Continued growth on these nuclei ultimately leads to a fully coalesced film, and we show in this research program that their initial density is correlated to the GaN dislocation density. In this 18 month program, we developed MOCVD growth methods to reduce GaN dislocation densities on sapphire from 5 x 10{sup 8} cm{sup -2} using our standard delay recovery growth technique to 1 x 10{sup 8} cm{sup -2} using an ultra-low nucleation density technique. For this research, we firmly established a correlation between the GaN nucleation thickness, the resulting nucleation density after annealing, and dislocation density of full GaN films grown on these nucleation layers. We developed methods to reduce the nuclei density while still maintaining the ability to fully coalesce the GaN films. Ways were sought to improve the GaN nuclei orientation by improving the sapphire surface smoothness by annealing prior to the NL growth. Methods to eliminate the formation of additional nuclei once the majority of GaN nuclei were developed using a silicon nitride treatment prior to the deposition of the nucleation layer. Nucleation layer thickness was determined using optical reflectance and the nucleation density was determined using atomic force microscopy (AFM) and Nomarski microscopy. Dislocation density was measured using X-ray diffraction and AFM after coating the surface with silicon nitride to delineate all dislocation types. The program milestone of producing GaN films with dislocation densities of 1 x 10{sup 8} cm{sup -2} was met by silicon nitride treatment of annealed sapphire followed by the multiple deposition of a low density of GaN nuclei followed by high temperature GaN growth. Details of this growth process and the underlying science are presented in this final report along with problems encountered in this research and recommendations for future work.

Koleske, Daniel David; Lee, Stephen Roger; Lemp, Thomas Kerr; Coltrin, Michael Elliott; Cross, Karen Charlene; Thaler, Gerald

2009-07-01T23:59:59.000Z

40

Time-resolved photoluminescence, positron annihilation, and Al0.23Ga0.77N/GaN heterostructure growth studies on low defect density polar and nonpolar freestanding GaN substrates grown by hydride vapor phase epitaxy  

Science Journals Connector (OSTI)

Time-resolved photoluminescence(TRPL) and positron annihilation measurements as well as Al0.23Ga0.77N/GaN heterostructuregrowth by metalorganic vapor phase epitaxy were carried out on very low defect density polar c-plane and nonpolar m-plane freestanding GaN (FS-GaN) substrates grown by hydride vapor phase epitaxy. Room-temperature photoluminescence(PL) lifetime for the near-band-edge (NBE) excitonic emission of the FS-GaN substrates increases with increasing positron diffusion length (L +); i.e. decreasing gross concentration of charged and neutral point defects and complexes. The best undoped c-plane FS-GaN exhibits record-long L + being 116?nm. The fast component of the PL lifetime for its NBE emission increases with temperature rise up to 100?K and levels off at approximately 1.1?ns. The result implies a saturation in thermal activation of nonradiative recombination centers. The surface and interface roughnesses for a Si-doped Al0.23Ga0.77N/GaN/Al0.18Ga0.82N/GaN heterostructure are improved by the use of FS-GaN substrates in comparison with the structure fabricated on a standard GaN template. The emission signals related to the recombination of a two-dimensional electron gas and excited holes are recognized for an Al0.23Ga0.77N/GaN single heterostructuregrown on the c-plane FS-GaN substrate.

S. F. Chichibu; K. Hazu; Y. Ishikawa; M. Tashiro; H. Namita; S. Nagao; K. Fujito; A. Uedono

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
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41

Composition and Bonding in Amorphous Carbon Films Grown by Ion Beam Assisted Deposition: Influence of the Assistance Voltage  

SciTech Connect (OSTI)

Amorphous carbon films have been grown by evaporation of graphite with concurrent Ar+ ions bombardment assistance. The ion energy has been varied between 0-800 V while keeping a constant ion to carbon atom arrival ratio. Film composition and density were determined by ion scattering techniques (RBS and ERDA), indicating a negligible hydrogen content and a density dependence with the assistance voltage. The bonding structure of the films has been studied by Raman and X-ray Absorption Near-Edge (XANES) spectroscopy. Different qualitative effects have been found depending on the ion energy range. For ion energies below 300 eV, there is a densification of the carbon layer due to the increase in the sp3 content. For ion energies above 300 eV sputtering phenomena dominate over densification, and thinner films are found with increasing assistance voltage until no film is grown over 600 V. The films with the highest SP3 content are grown with intermediate energies between 200-300 V.

Albella, J.M.; Banks, J.C.; Climent-Font, A.; Doyle, B.L.; Gago, R.; Jimenez, I.; Terminello, L.J.

1998-11-12T23:59:59.000Z

42

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

SciTech Connect (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

43

Characterization of gallium-doped CdS thin films grown by chemical bath Hani Khallaf a  

E-Print Network [OSTI]

Characterization of gallium-doped CdS thin films grown by chemical bath deposition Hani Khallaf In-situ doping with group III elements has been widely used to decrease the dark resistivity of CdS technique for aluminum in-situ doping of CdS. We have also shown that due to extremely low solubility

Chow, Lee

44

Topological insulator Bi 2 Se 3 thin films grown on double-layer graphene by molecular beam epitaxy  

Science Journals Connector (OSTI)

Atomically flat thin films of topological insulator Bi 2 Se 3 have been grown on double-layer graphene formed on 6H–SiC(0001) substrate by molecular beam epitaxy. By a combined study of reflection high energy electron diffraction and scanning tunneling microscopy we identified the Se-rich condition and temperature criterion for layer-by-layer growth of epitaxial Bi 2 Se 3 films. The as-grown films without doping exhibit a low defect density of 1.0 ± 0.2 × 10 11 / cm 2 and become a bulk insulator at a thickness of ten quintuple layers as revealed by in situ angle resolved photoemission spectroscopy measurement.

Can-Li Song; Yi-Lin Wang; Ye-Ping Jiang; Yi Zhang; Cui-Zu Chang; Lili Wang; Ke He; Xi Chen; Jin-Feng Jia; Yayu Wang; Zhong Fang; Xi Dai; Xin-Cheng Xie; Xiao-Liang Qi; Shou-Cheng Zhang; Qi-Kun Xue; Xucun Ma

2010-01-01T23:59:59.000Z

45

Homogeneous AlGaN/GaN superlattices grown on free-standing (1100) GaN substrates by plasma-assisted molecular beam epitaxy  

SciTech Connect (OSTI)

Two-dimensional and homogeneous growth of m-plane AlGaN by plasma-assisted molecular beam epitaxy has been realized on free-standing (1100) GaN substrates by implementing high metal-to-nitrogen (III/N) flux ratio. AlN island nucleation, often reported for m-plane AlGaN under nitrogen-rich growth conditions, is suppressed at high III/N flux ratio, highlighting the important role of growth kinetics for adatom incorporation. The homogeneity and microstructure of m-plane AlGaN/GaN superlattices are assessed via a combination of scanning transmission electron microscopy and high resolution transmission electron microscopy (TEM). The predominant defects identified in dark field TEM characterization are short basal plane stacking faults (SFs) bounded by either Frank-Shockley or Frank partial dislocations. In particular, the linear density of SFs is approximately 5 × 10{sup ?5} cm{sup ?1}, and the length of SFs is less than 15 nm.

Shao, Jiayi; Malis, Oana [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States) [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Zakharov, Dmitri N. [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States)] [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States); Edmunds, Colin [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States)] [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Manfra, Michael J. [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States) [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 49707 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 49707 (United States)

2013-12-02T23:59:59.000Z

46

Structural defects in GaN revealed by Transmission Electron Microscopy  

SciTech Connect (OSTI)

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

Liliental-Weber, Zuzanna

2014-04-18T23:59:59.000Z

47

Growth mechanism and composition of ultrasmooth a-C:H:Si films grown from energetic ions for superlubricity  

SciTech Connect (OSTI)

Growth mechanism and ion energy dependence of composition of ultrasmooth a-C:H:Si films grown from ionization of tetramethylsilane (TMS) and toluene mixture at a fixed gas ratio have been investigated by varying the applied bias voltage. The dynamic scaling theory is employed to evaluate the roughness evolution of a-C:H:Si films, and to extract roughness and growth exponents of ????0.51 and ????0, respectively. The atomically smooth surface of a-C:H:Si films with Ra???0.1?nm is thermally activated by the energetic ion-impact induced subsurface “polishing” process for ion dominated deposition. The ion energy (bias voltage) plays a paramount role in determining the hydrogen incorporation, bonding structure and final stoichiometry of a-C:H:Si films. The hydrogen content in the films measured by ERDA gradually decreases from 36.7 to 17.3 at. % with increasing the bias voltage from 0.25 to 3.5?kV, while the carbon content in the films increases correspondingly from 52.5 to 70.1 at. %. The Si content is kept almost constant at ?9–10 at. %. Depending on the ion-surface interactions, the bonding structure of a-C:H:Si films grown in different ion energy regions evolves from chain-developed polymer-like to cross-linked diamond-like to sp{sup 2}-bonded a–C as revealed by XPS, Raman, and FTIR analysis. Such a structural evolution is reflected in their measured nanomechanical properties such as hardness, modulus, and compressive stress. An enhanced viscoplastic behavior (i.e., viscoplastic exponent of ?0.06) is observed for polymeric a-C:H:Si films. A hydrogen content threshold (H?>?20 at. %) exists for the as-grown a-C:H:Si films to exhibit superlow friction in dry N{sub 2} atmosphere. An extremely low friction coefficient of ?0.001 can be obtained for polymer-like a-C:H:Si film. These near-frictionless a-C:H:Si films are strongly promising for applications in industrial lubricating systems.

Chen, Xinchun, E-mail: chenxc1213@gmail.com; Kato, Takahisa [Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656 (Japan)

2014-01-28T23:59:59.000Z

48

Electrical properties of scandium nitride epitaxial films grown on (100) magnesium oxide substrates by molecular beam epitaxy  

SciTech Connect (OSTI)

Scandium nitride (ScN) films were grown on (100) MgO single crystals by a molecular beam epitaxy method. The effects of growth conditions, including [Sc]/[N] ratio, growth temperature, and nitrogen radical state, on the electrical properties of the ScN films were studied. The ScN films comprised many small columnar grains. Hall coefficient measurements confirmed that the ScN films were highly degenerate n-type semiconductors and that the carrier concentration of the ScN films was sensitive to the growth temperature and the nitrogen radical states during the film growth. The carrier concentrations of the ScN films ranged from 10{sup 19}–10{sup 21} cm{sup ?3} while the Hall mobilities ranged from 50–130 cm{sup 2}·V{sup ?1}·s{sup ?1} for undoped films. The temperature-dependent Hall coefficient measurements showed that the carrier concentration is nearly independent of temperature, indicating that the change in resistivity with temperature is explained by a change in the Hall mobility. The temperature-dependence of the Hall mobility was strongly affected by the growth conditions.

Ohgaki, Takeshi; Watanabe, Ken; Adachi, Yutaka; Sakaguchi, Isao; Hishita, Shunichi; Ohashi, Naoki; Haneda, Hajime [Environment and Energy Materials Research Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [Environment and Energy Materials Research Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2013-09-07T23:59:59.000Z

49

Surface structural analysis of LiF(100) thin films grown on Pt(111)  

SciTech Connect (OSTI)

The surface structure of a multilayer LiF(100) thin film grown on Pt(111) from the vapor has been determined by the automated tensor low energy electron diffraction (LEED) method. The final structure, which refined to a Pendry R-factor (RP) of 0.24, had a surface corrugation (D1) of 0.24+-0.04 Angstrom due to the Li+ being displaced towards the bulk, leaving the initially coplanar F - unshifted. A similar intralayer corrugation due to the movement of the Li+ was also observed in the layer immediately under the surface layer, although to a lesser degree: D2=0.07+-0.04 Angstrom. This asymmetric relaxation resulted in the reduction of the first interlayer spacing, d(F2-Li1), to 1.77+-0.0 6 Angstrom from the ideal value of 2.01 Angstrom. The second interlayer spacing, d(Li3-F2), was within error bars of the bulk value, 2.01 Angstrom.

Roberts, J.G.; Van Hove, M.A.; Somorjai, G.A.

2002-08-29T23:59:59.000Z

50

Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction  

SciTech Connect (OSTI)

The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

Roberts, J.G.

2000-05-01T23:59:59.000Z

51

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique  

Science Journals Connector (OSTI)

An ultraviolet (UV) laser lift-off (LLO) technique was presented to form a roughened surface morphology on GaN membrane grown by...

Ting Wang; Xia Guo; Yuan Fang; GuangDi Shen

2007-04-01T23:59:59.000Z

52

P-type doping of GaN  

SciTech Connect (OSTI)

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

Wong, R.K.

2000-04-10T23:59:59.000Z

53

A novel integrated structure of thin film GaN LED with ultra-low thermal resistance  

Science Journals Connector (OSTI)

This study proposes a novel packaging structure for vertical thin-GaN LED applications by integration of LED chip and silicon-based packaging process. The vertical thin film LED is...

Wen, Shih-Yi; Hu, Hung-Lieh; Tsai, Yao-Jun; Hsu, Chen-Peng; Lin, Re-Ching; Horng, Ray Hua

2014-01-01T23:59:59.000Z

54

Stoichiometric, nonstoichiometric, and locally nonstoichiometric SrTiO{sub 3} films grown by molecular beam epitaxy  

SciTech Connect (OSTI)

SrTiO{sub 3} films were grown by reactive molecular beam epitaxy to have varying degrees of both global and local cationic nonstoichiometries (with stoichiometry defined as a 1:1 ratio of Sr:Ti). Slight global excesses of Sr and Ti resulted in two-fold reconstructions in the reflection high-energy electron diffraction patterns along the [110] and [100] azimuths, respectively. Larger global nonstoichiometries (2:1 and 1:2 ratios) were also accommodated into the film's crystalline structure and affected the long-range crystalline order as observed in the x-ray diffraction patterns, both of which were related to the parent perovskite pattern. Local nonstoichiometries were introduced by depositing multiple monolayers (MLs) (from 2 to 33) of SrO and TiO{sub 2} in an alternating fashion, while maintaining the global SrTiO{sub 3} stoichiometry. These layered structures of SrO and TiO{sub 2} blocks inter-reacted during growth to form highly crystalline epitaxial SrTiO{sub 3}. Films grown in this manner with blocks thicker than 8 MLs were fully relaxed and, when the block thicknesses ranged between 8 and 10 MLs, the full widths at half maxima of 2{theta} peaks were narrower than the standard SrTiO{sub 3} films having blocks 1 ML thick.

Fisher, P.; Du, H.; Skowronski, M.; Salvador, P. A. [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Maksimov, O. [Electro-Optics Center, Pennsylvania State University, Freeport, Pennsylvania 16229 (United States); Weng, X. [Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2008-01-01T23:59:59.000Z

55

Effects of nitrogen on the growth and optical properties of ZnO thin films grown by pulsed laser deposition  

Science Journals Connector (OSTI)

ZnO thin films were grown using pulsed laser deposition by ablating a Zn target in various mixtures of O2 and N2. The presence of N2 during deposition was found to affect the growth of the ZnO thin films and their optical properties. Small N2 concentrations during growth led to strong acceptor-related photoluminescence (PL), while larger concentrations affected both the intensity and temperature dependence of the emission peaks. In addition, the PL properties of the annealed ZnO thin films are associated with the N2 concentration during their growth. The possible role of nitrogen in ZnO growth and annealing is discussed.

J B Cui; M A Thomas; Y C Soo; H Kandel; T P Chen

2009-01-01T23:59:59.000Z

56

Thermal treatment induced change of diluted oxygen doped ZnTe films grown by metal-organic chemical vapor deposition  

Science Journals Connector (OSTI)

In this paper the authors report the growth of diluted oxygen doped ZnTe films (ZnTe:O) by metal-organic chemical vapor deposition (MOCVD). The effect of a post thermal annealing on the properties of the highly mismatched films has been investigated. It is found that the in-situ doping leads to an effective incorporation of oxygen into ZnTe films with different occupation configurations either on Zn or on Te site. The subsequent annealing process in a vacuum ambient leads to an enhancement of the oxygen incorporation into the ZnTe:O films due to the diffusion of the residual oxygen while the annealing with the same as-grown sample covered on top of the surface (denoted as “face-to-face” annealing in the text) is beneficial to the improvement of the film quality with manifest intermediate band emission at around 1.9?eV as revealed by the low-temperature photoluminescence. This study indicates that the mass-productive MOCVD technique may be suitable for the growth of highly mismatched ZnTe:O films for the application of the intermediate band solar cell.

2014-01-01T23:59:59.000Z

57

Structure disorder degree of polysilicon thin films grown by different processing: Constant C from Raman spectroscopy  

SciTech Connect (OSTI)

Flat, low-stress, boron-doped polysilicon thin films were prepared on single crystalline silicon substrates by low pressure chemical vapor deposition. It was found that the polysilicon films with different deposition processing have different microstructure properties. The confinement effect, tensile stresses, defects, and the Fano effect all have a great influence on the line shape of Raman scattering peak. But the effect results are different. The microstructure and the surface layer are two important mechanisms dominating the internal stress in three types of polysilicon thin films. For low-stress polysilicon thin film, the tensile stresses are mainly due to the change of microstructure after thermal annealing. But the tensile stresses in flat polysilicon thin film are induced by the silicon carbide layer at surface. After the thin film doped with boron atoms, the phenomenon of the tensile stresses increasing can be explained by the change of microstructure and the increase in the content of silicon carbide. We also investigated the disorder degree states for three polysilicon thin films by analyzing a constant C. It was found that the disorder degree of low-stress polysilicon thin film larger than that of flat and boron-doped polysilicon thin films due to the phase transformation after annealing. After the flat polysilicon thin film doped with boron atoms, there is no obvious change in the disorder degree and the disorder degree in some regions even decreases.

Wang, Quan, E-mail: wangq@mail.ujs.edu.cn [School of mechanical engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhang, Yanmin; Hu, Ran; Ren, Naifei [School of mechanical engineering, Jiangsu University, Zhenjiang 212013 (China); Ge, Daohan [School of mechanical engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-11-14T23:59:59.000Z

58

YBCO Films and YSZ Buffer Layers Grown in Situ on Silicon by Pulsed Laser Deposition  

Science Journals Connector (OSTI)

Attempts to grow high quality YBCO (Y1Ba2Cu3O7??...) films on bare silicon substrates have been hindered by substrate-film reactions, which are substantial even at growth temperatures as low as 550 C (Fenner et a...

D. K. Fork; G. A. N. Connell; D. B. Fenner…

1990-01-01T23:59:59.000Z

59

ECR Nb Films Grown on Amorphous and Crystalline Cu Substrates: Influence of Ion Energy  

SciTech Connect (OSTI)

In the pursuit of niobium (Nb) films with similar performance with the commonly used bulk Nb surfaces for Superconducting RF (SRF) applications, significant progress has been made with the development of energetic condensation deposition techniques. Using energetic condensation of ions extracted from plasma generated by Electron Cyclotron Resonance, it has been demonstrated that Nb films with good structural properties and RRR comparable to bulk values can be produced on metallic substrates. The controlled incoming ion energy enables a number of processes such as desorption of adsorbed species, enhanced mobility of surface atoms and sub-implantation of impinging ions, thus producing improved film structures at lower process temperatures. Particular attention is given to the nucleation conditions to create a favourable template for growing the final surface exposed to SRF fields. The influence of the deposition energy on film growth on copper substrates is investigated with the characterization of the film surface, structure, superconducting properties and RF performance.

Valente, Anne-Marie [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Eremeev, Grigory V. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Spradlin, Joshua K. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Phillips, H. Lawrence [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Cao, C. [Illinois Inst. of Technology, Chicago, IL (United States); Proslier, Thomas [Argonne National Laboratory, Argonne, IL (United States); Tao, T. [Univ. of Illinois at Chicago, Chicago, IL (United States)

2014-02-01T23:59:59.000Z

60

Nanoporous Ptn+?CeOx catalyst films grown on carbon substrates  

Science Journals Connector (OSTI)

Deposition of the Pt doped cerium oxide catalyst layers on carbon nanotubes and flat carbon substrates by magnetron sputtering leads to growth of solid solution films composed of nanorods oriented perpendicularly to the substrate surface forming fractal like highly porous structure. The films contain only cationic Pt2+ and Pt4+. Cerium oxide is partially reduced. The catalyst films reveal high catalytic activity as anode catalyst in proton exchange membrane fuel cells. Preparation of nanoporous structures by sputtering shows that this technique is suitable for preparation of catalyst for micro fuel cell systems made by planar technology.

V. Matolín; R. Fiala; I. Khalakhan; J. Lavková; M. Václavů M. Vorokhta

2012-01-01T23:59:59.000Z

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61

Field emission from bias-grown diamond thin films in a microwave plasma  

DOE Patents [OSTI]

A method of producing diamond or diamond like films in which a negative bias is established on a substrate with an electrically conductive surface in a microwave plasma chemical vapor deposition system. The atmosphere that is subjected to microwave energy includes a source of carbon, nitrogen and hydrogen. The negative bias is maintained on the substrate through both the nucleation and growth phase of the film until the film is continuous. Biases between -100V and -200 are preferred. Carbon sources may be one or more of CH.sub.4, C.sub.2 H.sub.2 other hydrocarbons and fullerenes.

Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (Naperville, IL); Ding, Ming Q. (Beijing, CN); Auciello, Orlando (Bolinbrook, IL)

2002-01-01T23:59:59.000Z

62

Transparent and conducting ZnO films grown by spray pyrolysis  

Science Journals Connector (OSTI)

ZnO films were prepared using the simple, flexible and cost-effective spray pyrolysis technique at different substrate temperatures and precursor molarity values. The films' structural, optical and electrical properties were investigated by x-ray diffraction, UV–VIS transmittance spectroscopy, profilometry and voltage–current–temperature (VIT) measurements. The films prepared at substrate temperatures above 400 °C appear better crystallized with (0?0?2) preferred orientation and exhibit higher visible transmittance (65–80%), higher electrical n-type semiconductor conductivity (10–50 (? cm)?1), lower activation energy (

Lazhar Hadjeris; Labidi Herissi; M Badreddine Assouar; Thomas Easwarakhanthan; Jamal Bougdira; Nadhir Attaf; M Salah Aida

2009-01-01T23:59:59.000Z

63

p-type conduction from Sb-doped ZnO thin films grown by dual ion beam sputtering in the absence of oxygen ambient  

SciTech Connect (OSTI)

Sb-doped ZnO (SZO) thin films were deposited on c-plane sapphire substrates by dual ion beam sputtering deposition system in the absence of oxygen ambient. The electrical, structural, morphological, and elemental properties of SZO thin films were studied for films grown at different substrate temperatures ranging from 200 °C to 600 °C and then annealed in situ at 800 °C under vacuum (pressure ?5 × 10{sup ?8} mbar). Films grown for temperature range of 200–500 °C showed p-type conduction with hole concentration of 1.374 × 10{sup 16} to 5.538 × 10{sup 16} cm{sup ?3}, resistivity of 66.733–12.758 ? cm, and carrier mobility of 4.964–8.846 cm{sup 2} V{sup ?1} s{sup ?1} at room temperature. However, the film grown at 600 °C showed n-type behavior. Additionally, current-voltage (I–V) characteristic of p-ZnO/n-Si heterojunction showed a diode-like behavior, and that further confirmed the p-type conduction in ZnO by Sb doping. X-ray diffraction measurements showed that all SZO films had (002) preferred crystal orientation. X-ray photoelectron spectroscopy analysis confirmed the formation of Sb{sub Zn}–2V{sub Zn} complex caused acceptor-like behavior in SZO films.

Kumar Pandey, Sushil; Kumar Pandey, Saurabh; Awasthi, Vishnu; Kumar, Ashish; Mukherjee, Shaibal [Hybrid Nanodevice Research Group, Discipline of Electrical Engineering, Indian Institute of Technology, Indore 453441 (India)] [Hybrid Nanodevice Research Group, Discipline of Electrical Engineering, Indian Institute of Technology, Indore 453441 (India); Deshpande, Uday P.; Gupta, Mukul [University Grants Commission Department of Atomic Energy (UGC DAE) Consortium for Scientific Research, Indore (India)] [University Grants Commission Department of Atomic Energy (UGC DAE) Consortium for Scientific Research, Indore (India)

2013-10-28T23:59:59.000Z

64

Low-temperature grown graphene films by using molecular beam epitaxy  

SciTech Connect (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

65

Identification of Defect Sites on SiO2 Thin Films Grown on Y. D. Kim, T. Wei, and D. W. Goodman*  

E-Print Network [OSTI]

Identification of Defect Sites on SiO2 Thin Films Grown on Mo(112) Y. D. Kim, T. Wei, and D. W properties of SiO2 thin films with a thickness of 0.7-0.8 nm are identical to those of bulk SiO2 properties of the corre- sponding bulk single crystals.1-4 In recent studies SiO2 single-crystalline thin

Goodman, Wayne

66

Top-gate thin-film transistors based on GaN channel layer Rongsheng Chen, Wei Zhou, and Hoi Sing Kwok  

E-Print Network [OSTI]

liquid gallium target. The GaN TFTs exhibit good electrical performance such as field effect mobility of 1 cm2 /Vs, threshold voltage of Ã?0.4 V, on/off current ratio of 105 , and subthreshold swing of 0 electrical sta- bility of ZnO-based TFTs is still a main issue preventing from commercialization.9 Bottom

67

ZnO film with ultra-low background electron concentration grown by plasma-assisted MBE using Mg film as the buffer layer  

SciTech Connect (OSTI)

Highlights: ? High quality ZnO film with ultra-low background electron concentration is grown by plasma-assisted molecular beam epitaxy using Mg film as a buffer layer. ? High resolution X-ray diffraction and photoluminescence (PL) spectroscopy indicate a high degree of crystallization. ? Hall measurement shows a carrier concentration as low as ?10{sup 14} cm{sup ?3}. ? The mechanism of the improved crystallinity is discussed in detail. -- Abstract: High quality ZnO epilayer with background electron concentration as low as 2.6 × 10{sup 14} cm{sup ?3} was obtained by plasma-assisted MBE on c-sapphire using a thin Mg film as the buffer layer. High-resolution XRD measurement shows a sharp (0 0 2) peak with full width at half maximum (FWHM) of only 0.029°. Photoluminescence spectroscopy presents a weak defect-related near-edge emission. A metal–semiconductor–metal (MSM) typed photodetector based on the material demonstrates a response of ?43 A/W under the bias of 1 V and an ON/OFF ratio of 10{sup 4}. This un-doped ZnO with ultra-low background electron concentration could be a promising starting material for p-type doping.

Chen, Mingming; Zhang, Quanlin; Su, Longxing; Su, Yuquan; Cao, Jiashi; Zhu, Yuan; Wu, Tianzhun; Gui, Xuchun [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China)] [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China); Yang, Chunlei [Center for Photovoltaics and Solar Energy, Shen Zhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shen Zhen (China)] [Center for Photovoltaics and Solar Energy, Shen Zhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shen Zhen (China); Xiang, Rong, E-mail: xiangr2@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China)] [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China); Tang, Zikang, E-mail: phzktang@ust.hk [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China) [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

2012-09-15T23:59:59.000Z

68

Optical, structural, and electrical properties of Mg{sub 2}NiH{sub 4} thin films in situ grown by activated reactive evaporation  

SciTech Connect (OSTI)

Mg{sub 2}NiH{sub 4} thin films have been prepared by activated reactive evaporation in a molecular beam epitaxy system equipped with an atomic hydrogen source. The optical reflection spectra and the resistivity of the films are measured in situ during deposition. In situ grown Mg{sub 2}NiH{sub 4} appears to be stable in vacuum due to the fact that the dehydrogenation of the Mg{sub 2}NiH{sub 4} phase is kinetically blocked. Hydrogen desorption only takes place when a Pd cap layer is added. The optical band gap of the in situ deposited Mg{sub 2}NiH{sub 4} hydride, 1.75 eV, is in good agreement with that of Mg{sub 2}NiH{sub 4} which has been formed ex situ by hydrogenation of metallic Pd capped Mg{sub 2}Ni films. The microstructure of these in situ grown films is characterized by a homogeneous layer with very small grain sizes. This microstructure suppresses the preferred hydride nucleation at the film/substrate interface which was found in as-grown Mg{sub 2}Ni thin films that are hydrogenated after deposition.

Westerwaal, R. J.; Slaman, M.; Broedersz, C. P.; Borsa, D. M.; Dam, B.; Griessen, R.; Borgschulte, A.; Lohstroh, W.; Kooi, B.; Brink, G. ten; Tschersich, K. G.; Fleischhauer, H. P. [Faculty of Sciences, Department of Physics and Astronomy, Condensed Matter Physics, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); GKSS-Research Center Geesthacht GmbH, WTP, Building 59 Max-Planck-Strasse 1, 21502 Geesthacht (Germany); Institut fuer Nanotechnologie, Forschungszentrum Karlsruhe GmbH, Postfach 36 40 76021 Karlsruhe (Germany); Department of Applied Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Institut fuer Schichten und Grenzflaechen, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany)

2006-09-15T23:59:59.000Z

69

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

SciTech Connect (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 Ts<200 ?C are amorphous while films grown at Ts>200 ?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

70

Structural properties of SrO thin films grown by molecular beam epitaxy on LaAlO{sub 3} substrates  

SciTech Connect (OSTI)

SrO films were grown on LaAlO{sub 3} substrates by molecular beam epitaxy and characterized using reflection high-energy electron diffraction (RHEED) and x-ray diffraction (XRD). The evolution of the RHEED pattern is discussed as a function of film thickness. 500 A thick SrO films were relaxed and exhibited RHEED patterns indicative of an atomically smooth surface having uniform terrace heights. Films had the epitaxial relationship (001){sub SrO}(parallel sign)(001){sub LaAlO{sub 3}}; [010]{sub SrO}(parallel sign)[110]{sub LaAlO{sub 3}}. This 45 deg. in-plane rotation minimizes mismatch and leads to films of high crystalline quality, as verified by Kikuchi lines in the RHEED patterns and narrow rocking curves of the (002) XRD peak.

Maksimov, O.; Heydemann, V. D.; Fisher, P.; Skowronski, M.; Salvador, P. A. [Electro-Optics Center, Pennsylvania State University, Freeport, Pennsylvania 16229 (United States); Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2006-12-25T23:59:59.000Z

71

Reactor design for uniform chemical vapor deposition-grown films without substrate rotation  

DOE Patents [OSTI]

A quartz reactor vessel for growth of uniform semiconductor films includes a vertical, cylindrical reaction chamber in which a substrate-supporting pedestal provides a horizontal substrate-supporting surface spaced on its perimeter from the chamber wall. A cylindrical confinement chamber of smaller diameter is disposed coaxially above the reaction chamber and receives reaction gas injected at a tangent to the inside chamber wall, forming a helical gas stream that descends into the reaction chamber. In the reaction chamber, the edge of the substrate-supporting pedestal is a separation point for the helical flow, diverting part of the flow over the horizontal surface of the substrate in an inwardly spiraling vortex.

Wanlass, Mark (Golden, CO)

1987-01-01T23:59:59.000Z

72

Reactor design for uniform chemical vapor deposition-grown films without substrate rotation  

DOE Patents [OSTI]

A quartz reactor vessel for growth of uniform semiconductor films includes a vertical, cylindrical reaction chamber in which a substrate-supporting pedestal provides a horizontal substrate-supporting surface spaced on its perimeter from the chamber wall. A cylindrical confinement chamber of smaller diameter is disposed coaxially above the reaction chamber and receives reaction gas injected at a tangent to the inside chamber wall, forming a helical gas stream that descends into the reaction chamber. In the reaction chamber, the edge of the substrate-supporting pedestal is a separation point for the helical flow, diverting part of the flow over the horizontal surface of the substrate in an inwardly spiraling vortex.

Wanlass, M.

1985-02-19T23:59:59.000Z

73

Reactor design for uniform chemical vapor deposition-grown films without substrate rotation  

SciTech Connect (OSTI)

A reactor vessel is described for chemical vapor deposition of a uniform semiconductor film on a substrate, comprising: a generally cylindrical reaction chamber for receiving a substrate and a flow of reaction gas capable of depositing a film on the substrate under the conditions of the chamber, the chamber having upper and lower portion and being oriented about a vertical axis; a supporting means having a substrate support surface generally perpendicular to the vertical axis for carrying the substrate within the lower portion of the reaction chamber in a predetermined relative position with respect to the upper portion of the reaction chamber, the upper portion including a cylindrically shaped confinement chamber. The confinement chamber has a smaller diameter than the lower portion of the reaction chamber and is positioned above the substrate support surface; and a means for introducing a reaction gas into the confinement chamber in a nonaxial direction so as to direct the reaction gas into the lower portion of the reaction chamber with a non-axial flow having a rotational component with respect to the vertical axis. In this way the reaction gas defines an inward vortex flow pattern with respect to the substrate surface.

Wanlass, M.

1987-03-17T23:59:59.000Z

74

Electrical transport and structural study of CuCr1 ? xMgxO2 delafossite thin films grown by pulsed laser deposition  

Science Journals Connector (OSTI)

The growth and properties of delafossites CuCr1 ? xMgxO2 thin films are examined. These films are grown by pulsed laser deposition. As a class of materials delafossites have received recent interest since some members show p-type behavior. While not considered true wide-bandgap materials due to a narrow indirect bandgap that fails to adsorb light due to a forbidden same parity transition, optical transparencies greater than 40% in the visible can be observed. In order to be useful for transparent device applications, CuCr1 ? xMgxO2 films are needed with low resistivity and high optical transparency. Epitaxial films of CuCr1 ? xMgxO2 were grown on c-sapphire, examining the effects of oxygen pressure and growth temperature on film properties. Films were realized with resistivity of ~ 0.02 ?-cm and optical transparency of 40% in the visible. The formation of a problematic secondary minority spinel phase of (Cu,Mg)Cr2O4 is discussed. While conductivity increases substantially with Mg doping, the incidence of the spinel phase increases as well.

P.W. Sadik; M. Ivill; V. Craciun; D.P. Norton

2009-01-01T23:59:59.000Z

75

Fabricating superconducting interfaces between artificially grown LaAlO{sub 3} and SrTiO{sub 3} thin films  

SciTech Connect (OSTI)

Realization of a fully metallic two-dimensional electron gas (2DEG) at the interface between artificially grown LaAlO{sub 3} and SrTiO{sub 3} thin films has been an exciting challenge. Here we present for the first time the successful realization of a superconducting 2DEG at interfaces between artificially grown LaAlO{sub 3} and SrTiO{sub 3} thin films. Our results highlight the importance of two factors—the growth temperature and the SrTiO{sub 3} termination. We use local friction force microscopy and transport measurements to determine that in normal growth conditions the absence of a robust metallic state at low temperature in the artificially grown LaAlO{sub 3}/SrTiO{sub 3} interface is due to the nanoscale SrO segregation occurring on the SrTiO{sub 3} film surface during the growth and the associated defects in the SrTiO{sub 3} film. By adopting an extremely high SrTiO{sub 3} growth temperature, we demonstrate a way to realize metallic, down to the lowest temperature, and superconducting 2DEG at interfaces between LaAlO{sub 3} layers and artificially grown SrTiO{sub 3} thin films. This study paves the way to the realization of functional LaAlO{sub 3}/SrTiO{sub 3} superlattices and/or artificial LaAlO{sub 3}/SrTiO{sub 3} interfaces on other substrates.

Li, Danfeng, E-mail: Danfeng.Li@unige.ch; Gariglio, Stefano; Cancellieri, Claudia; Fête, Alexandre; Stornaiuolo, Daniela; Triscone, Jean-Marc [DPMC, University of Geneva, 24 Quai Ernest Ansermet, 1211 Geneva (Switzerland)

2014-01-01T23:59:59.000Z

76

Si in GaN -- On the nature of the background donor  

SciTech Connect (OSTI)

A characterization of the Si impurity in GaN is performed by Raman spectroscopy. Applying hydrostatic pressure up to 25 GPa the authors study the behavior of the LO phonon-plasmon mode in a series of high mobility Si doped GaN films. In contrast to earlier results on unintentionally doped bulk GaN crystals no freeze out of the free carriers could be observed in Si doped samples. The authors find that Si is a shallow hydrogenic donor throughout the pressure range studied. This result positively excludes Si incorporation as a dominant source of free electrons in previously studied bulk GaN samples.

Wetzel, C.; Chen, A.L.; Suski, T.; Ager, J.W. III; Walukiewicz, W. [Lawrence Berkeley National Lab., CA (United States). Materials Science Div.

1996-08-01T23:59:59.000Z

77

Large area supersonic jet epitaxy of AlN, GaN, and SiC on silicon  

SciTech Connect (OSTI)

AlN, GaN, and SiC thin films were grown on 100 mm diameter Si(111) and Si(100) substrates using Supersonic Jet Epitaxy (SJE). Precursor gases were seeded in lighter mass carrier gases and free jets were formed using novel slit-jet apertures. The jet design, combined with substrate rotation, allowed for a uniform flux distribution over a large area of a 100 mm wafer at growth pressures of 1--20 mTorr. Triethylaluminum, triethylgallium, and ammonia were used for nitride growth, while disilane, acetylene, and methylsilane were used for SiC growth. The films were characterized by in situ optical reflectivity, x-ray diffraction (XRD), atomic force microscopy (AFM), and spectroscopic ellipsometry (SE).

Lauhon, L.J.; Ustin, S.A.; Ho, W. [Cornell Univ., Ithaca, NY (United States). Dept. of Physics

1997-12-31T23:59:59.000Z

78

Microcrystalline Si films grown at low temperatures (90-220 deg. C) with high rates in atmospheric-pressure VHF plasma  

SciTech Connect (OSTI)

This work deals with the structural properties of microcrystalline silicon (muc-Si:H) films grown at low temperatures (90-220 deg. C) with high rates in atmospheric-pressure He/H{sub 2}/SiH{sub 4} plasma, which is excited by a 150 MHz very high frequency power using a porous carbon electrode. This plasma permits to enhance the chemical reactions both in gas phase and on the film-growing surface, while suppressing ion impingement upon the surface. Raman crystalline volume fractions of the muc-Si:H films are studied in detail as functions of film thickness and substrate temperature (T{sub sub}). The results show that the muc-Si:H film deposited with 50 (SCCM) (SCCM denotes standard cubic centimeters per minute at STP) SiH{sub 4} has no amorphous transition layers at the film/substrate interface in spite of the high deposition rate of 6.4 nm/s, which is verified by the cross sectional observations with a transmission electron microscope. In addition, the T{sub sub} dependence of Raman crystallinity of the muc-Si:H films indicates that a highly crystallized muc-Si:H film grows even when T{sub sub} is reduced to 90 deg. C. Further systematic studies are needed for both device applications and deposition on thermally sensitive plastic materials.

Kakiuchi, Hiroaki; Ohmi, Hiromasa; Ouchi, Kentaro; Tabuchi, Keita; Yasutake, Kiyoshi [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2009-07-01T23:59:59.000Z

79

Investigation of epitaxial arrangement and electronic structure of a La@C82 film grown on an MoS2 surface  

Science Journals Connector (OSTI)

Molecular arrangement and electronic structure of a La@C82 film epitaxially grown on an MoS2 surface have been studied using reflection high-energy electron diffraction and electron energy-loss spectroscopy (EELS). It was revealed that La@C82 molecules form a close-packed hexagonal lattice on a cleaved face of MoS2 with the intermolecular distance of 1.13±0.03 nm. EELS of the La@C82 film in the valence excitation region indicated seven peaks coming from ???* transitions together with the ?-plasmon excitation. The absence of a distinct band gap means that the La@C82 epitaxial film is not semiconducting, but metallic or semimetallic. From the EELS result, we propose an electronic structure diagram of the La@C82 epitaxial film.

K. Iizumi, Y. Uchino, K. Ueno, A. Koma, K. Saiki, Y. Inada, K. Nagai, Y. Iwasa, and T. Mitani

2000-09-15T23:59:59.000Z

80

Thermal stability of Al- and Zr-doped HfO{sub 2} thin films grown by direct current magnetron sputtering  

SciTech Connect (OSTI)

Ultrathin HfO{sub 2} dielectric films doped with Al and Zr were grown on p-type Si(100) substrates by dc magnetron sputtering, and their microstructural and electrical properties were examined. Compositions and chemical states of the dielectric films were analyzed by Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy. The HfO{sub 2} films doped with Zr were crystallized even from the as-deposited state, however, the crystallization temperature of the HfO{sub 2} film doped with 16% Al{sub 2}O{sub 3} was delayed up to 900 deg. C. As the annealing temperature increases, high-resolution transmission electron microscopy analyses of all doped HfO{sub 2} films showed an increase of the interfacial layer thickness due to the diffusion of small partial pressure of oxygen in annealing ambient. Our results also showed that the addition of Al{sub 2}O{sub 3} to 14% is not useful for blocking the oxygen diffusion through the (HfO{sub 2}){sub 0.86}(Al{sub 2}O{sub 3}){sub 0.14} film. From the capacitance-voltage measurements, the dielectric constants of the Al- and Zr-doped HfO{sub 2} thin films were measured to be 18.7 and 7.6, respectively.

Hong, Yeong-Eui; Kim, Yong-Seok; Do, Kihoon; Lee, Dongwon; Ko, Dae-Hong; Ku, Ja-Hum; Kim, Hyoungsub [Department of Ceramic Engineering, Yonsei University, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul 120-749 (Korea, Republic of); Semiconductor R and D Division, Samsung Electronics Co, Ltd., San no. 24, Nongseo-Ri, Kiheung-Eup, Yongin-City, Kyunggi-Do 449-711 (Korea, Republic of); Department of Advanced Materials Engineering, Sungkyunkwan University, 300 Chunchun-Dong, Jangan-Ku, Suwon 440-746 (Korea, Republic of)

2005-09-15T23:59:59.000Z

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.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Study of stable p-type conductivity in bismuth-doped ZnO films grown by pulsed-laser deposition  

Science Journals Connector (OSTI)

Bismuth-doped p-type ZnO films were grown on sapphire (0001) substrates by pulsed-laser deposition at 600?°C in 1?mT oxygen pressure. The photoluminescence (PL) property of the as-grown and post-annealed Bi-doped p-type ZnO films at 10–300?K has been investigated. A well-resolved PL spectrum was obtained with acceptor bound exciton emission and conduction band to acceptor transition giving direct evidence for the creation of acceptors. The acceptor energy level of the bismuth dopant is found to be 0.13?eV above valance band. The binding energy between the acceptor and the exciton measured as a function of temperature was found to be 14?meV. A hole concentration of 5.36?1018cm?3 and a mobility of 8.9?cm2/Vs was obtained for 3% bismuth-doped and annealed ZnO thin films. This study suggests that bismuth is an excellent dopant to obtain stable and reproducible p-type conductivity in ZnO for the application in optoelectronic devices.

J. W. Lee; N. G. Subramaniam; J. C. Lee; S. Kumar S; T. W. Kang

2011-01-01T23:59:59.000Z

82

Structural and magnetic properties of Ge{sub 1-x}Mn{sub x} thin films grown on Ge (001) substrates  

SciTech Connect (OSTI)

We investigate the structural and magneto-optical properties of Mn-doped Ge (Ge{sub 1-x}Mn{sub x}) films with self-organized nanocolumns, grown on Ge (001) substrates by molecular beam epitaxy (MBE), in which the substrate temperature (T{sub S}) and growth rate (R{sub G}) are varied. Transmission electron microscopy (TEM) observations and magnetic circular dichroism (MCD) measurements reveal that Mn-rich nanocolumnar precipitation is formed in the Ge{sub 1-x}Mn{sub x} films grown at T{sub S} {<=} 100 deg. C, with keeping the size and spacing. At higher T{sub S} ({>=}150 deg. C), ferromagnetic Mn{sub 5}Ge{sub 3} clusters are formed. It is also found that the Mn distribution in the Ge{sub 1-x}Mn{sub x} films can be controlled: By lowering T{sub S} or increasing R{sub G}, the Mn content x{sub nc} in the nanocolumns decreases and Mn atoms are more distributed into the Ge matrix, and eventually the magnetic properties are changed. The formation of the nanocolumns is explained by the spinodal decomposition in the layer-by-layer growth mode. We analyzed the periodicity and Mn content x{sub nc} of nanocolumns by using the Cahn-Hilliard equation.

Yada, Shinsuke; Nam Hai, Pham; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Sugahara, Satoshi [Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259-G2-14 Nagatsuta, Yokohama, Kanagawa 226-8502 (Japan)

2011-10-01T23:59:59.000Z

83

Shallow acceptor and hydrogen impurity in p-type arsenic-doped ZnMgO films grown by radio frequency magnetron sputtering  

Science Journals Connector (OSTI)

Arsenic-doped ZnMgO films were fabricated on SiO2 by the radio frequency magnetron sputtering technique at different substrate temperatures during growth. The yielded films were characterized by room temperature Hall measurement, x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, secondary ion mass spectroscopy, nuclear reaction analysis and low-temperature photoluminescence. As-doped samples grown at low substrate temperature (350 °C) were n-type conducting (n ~ 1018 cm?3), with evidence showing that the hydrogen impurity was an important shallow donor associated with the observed n-type conduction. Conversion of n-type to p-type conduction being observed at the substrate temperature of ~400 °C was associated with the formation of the AsZn(VZn)2 shallow acceptor complex and the drastic reduction of the hydrogen content.

J C Fan; G W Ding; S Fung; Z Xie; Y C Zhong; K S Wong; G Brauer; W Anwand; D Grambole; C C Ling

2010-01-01T23:59:59.000Z

84

Colossal Electroresistive Properties Of CSD Grown Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3} Films For Nonvolatile Memory Applications  

SciTech Connect (OSTI)

Colossal electroresistance effects upon application of electric field in perovskite oxide Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3}(PCMO) thin films, which is a promising candidate for resistance random access memory (RRAM) device have been investigated. Nanocrystalline PCMO films were grown on SiO{sub 2} substrates by chemical solution deposition and crystallized at 700 deg. C under different gas atmospheres. Four terminal current voltage characteristics of Ag/PCMO/Ag planar geometry exhibited a sharp transition from a low resistance state (LRS) to a high resistance state (HRS) with a resistance switching ratio of as high as 1100% at room temperature. Nonvolatility and high retention was confirmed by electric pulse induced resistive switching measurements. The resistance switching ratios were found to depend on the annealing conditions, suggesting an interaction between the nonlattice oxygen and oxygen vacancies and/or the cationic vacancy.

Bhavsar, K. H.; Joshi, U. S. [Department of Physics, University School of Sciences, Gujarat University, Ahmedabad-380 009 (India)

2010-12-01T23:59:59.000Z

85

Control of morphology for enhanced electronic transport in PECVD-grown a-Si : H Thin Films  

E-Print Network [OSTI]

Solar cells have become an increasingly viable alternative to traditional, pollution causing power generation methods. Although crystalline silicon (c-Si) modules make up most of the market, thin films such as hydrogenated ...

Castro Galnares, Sebastián

2010-01-01T23:59:59.000Z

86

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

SciTech Connect (OSTI)

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

87

Residual Stress in CVD-grown 3C-SiC Films on Si Substrates Alex A. Volinsky1  

E-Print Network [OSTI]

on 50 mm (100) and (111) Si substrates in a hot-wall CVD reactor. The film tensile residual stress was non-uniform, having a linear profile along the growth direction. This presented a challenge of using to deposit SiC on Si wafers due to their high quality and low cost, in comparison to SiC substrates. However

Volinsky, Alex A.

88

High spin polarization at room temperature in Ge-substituted Fe{sub 3}O{sub 4} epitaxial thin film grown under high oxygen pressure  

SciTech Connect (OSTI)

Epitaxial thin films of room-temperature ferrimagnetic (Fe,Ge){sub 3}O{sub 4} were fabricated using pulsed laser deposition. Films with a single-phase spinel structure were grown under high oxygen pressures (0.01–0.6?Pa). The carrier transport across (Fe,Ge){sub 3}O{sub 4}/Nb:SrTiO{sub 3} interface was studied to estimate the spin polarization of (Fe, Ge){sub 3}O{sub 4}. Current–voltage curves of Fe{sub 2.8}Ge{sub 0.2}O{sub 4}/Nb:SrTiO{sub 3} junction showed rectifying behavior even at 300?K whereas Fe{sub 3}O{sub 4}/Nb:SrTiO{sub 3} junction showed ohmic behavior. Calculations based on a model for a Schottky contact with a ferromagnetic component yielded a spin polarization of 0.50 at 300?K for Fe{sub 2.8}Ge{sub 0.2}O{sub 4}, indicating its potential as a promising spin injector.

Seki, Munetoshi, E-mail: m-seki@ee.t.u-tokyo.ac.jp; Takahashi, Masanao; Ohshima, Toshiyuki; Yamahara, Hiroyasu; Tabata, Hitoshi [Department of Electrical Engineering and Information Systems, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)] [Department of Electrical Engineering and Information Systems, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2013-11-18T23:59:59.000Z

89

Electronic structures and magnetic moments of Co{sub 3}FeN thin films grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We evaluated electronic structures and magnetic moments in Co{sub 3}FeN epitaxial films on SrTiO{sub 3}(001). The experimentally obtained hard x-ray photoemission spectra of the Co{sub 3}FeN film have a good agreement with those calculated. Site averaged spin magnetic moments deduced by x-ray magnetic circular dichroism were 1.52 ?{sub B} per Co atom and 2.08 ?{sub B} per Fe atom at 100 K. They are close to those of Co{sub 4}N and Fe{sub 4}N, respectively, implying that the Co and Fe atoms randomly occupy the corner and face-centered sites in the Co{sub 3}FeN unit cell.

Ito, Keita; Sanai, Tatsunori; Yasutomi, Yoko; Toko, Kaoru; Honda, Syuta; Suemasu, Takashi [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)] [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Zhu, Siyuan; Kimura, Akio [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)] [Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ueda, Shigenori [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan)] [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan); Takeda, Yukiharu; Saitoh, Yuji [Condensed Matter Science Division, Japan Atomic Energy Agency (JAEA), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan)] [Condensed Matter Science Division, Japan Atomic Energy Agency (JAEA), 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan); Imai, Yoji [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan) [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

2013-12-02T23:59:59.000Z

90

Bipolar resistive switching characteristics of low temperature grown ZnO thin films by plasma-enhanced atomic layer deposition  

SciTech Connect (OSTI)

ZnO films deposited by plasma-enhanced atomic layer deposition (PEALD) have been used to investigate resistive memory behavior. The bipolar resistance switching properties were observed in the Al/PEALD-ZnO/Pt devices. The resistance ratio for the high and low resistance states (HRS/LRS) is more than 10{sup 3}, better than ZnO devices deposited by other methods. The dominant conduction mechanisms of HRS and LRS are trap-controlled space charge limited current and Ohmic behavior, respectively. The resistive switching behavior is induced upon the formation/disruption of conducting filaments. This study demonstrated that the PEALD-ZnO films have better properties for the application in 3D resistance random access memory.

Zhang Jian; Yang Hui; Zhang Qilong [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)] [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Dong Shurong [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China)] [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China); Luo, J. K. [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China) [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027 (China); Institute of Material Research and Innovation, Bolton University, Deane Road, Bolton BL3 5AB (United Kingdom)

2013-01-07T23:59:59.000Z

91

Precise calibration of Mg concentration in Mg{sub x}Zn{sub 1-x}O thin films grown on ZnO substrates  

SciTech Connect (OSTI)

The growth techniques for Mg{sub x}Zn{sub 1-x}O thin films have advanced at a rapid pace in recent years, enabling the application of this material to a wide range of optical and electrical applications. In designing structures and optimizing device performances, it is crucial that the Mg content of the alloy be controllable and precisely determined. In this study, we have established laboratory-based methods to determine the Mg content of Mg{sub x}Zn{sub 1-x}O thin films grown on ZnO substrates, ranging from the solubility limit of x {approx} 0.4 to the dilute limit of x < 0.01. For the absolute determination of Mg content, Rutherford backscattering spectroscopy is used for the high Mg region above x = 0.14, while secondary ion mass spectroscopy is employed to quantify low Mg content. As a lab-based method to determine the Mg content, c-axis length is measured by x-ray diffraction and is well associated with Mg content. The interpolation enables the determination of Mg content to x = 0.023, where the peak from the ZnO substrate overlaps the Mg{sub x}Zn{sub 1-x}O peak in standard laboratory equipment, and thus limits quantitative determination. At dilute Mg contents below x = 0.023, the localized exciton peak energy of the Mg{sub x}Zn{sub 1-x}O films as measured by photoluminescence is found to show a linear Mg content dependence, which is well resolved from the free exciton peak of ZnO substrate down to x = 0.0043. Our results demonstrate that x-ray diffraction and photoluminescence in combination are appropriate methods to determine Mg content in a wide Mg range from x = 0.004 to 0.40 in a laboratory environment.

Kozuka, Y.; Falson, J.; Tsukazaki, A. [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Segawa, Y.; Makino, T. [Cross-Correlated Materials Research Group (CMRG) and Correlated Electron Research Group (CERG), RIKEN-Advanced Science Institute, Wako 351-0198 (Japan); Kawasaki, M. [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Cross-Correlated Materials Research Group (CMRG) and Correlated Electron Research Group (CERG), RIKEN-Advanced Science Institute, Wako 351-0198 (Japan)

2012-08-15T23:59:59.000Z

92

Nucleation and Growth of GaN on GaAs (001) Substrates  

SciTech Connect (OSTI)

The nucleation of GaN thin films on GaAs is investigated for growth at 620 "C. An rf plasma cell is used to generate chemically active nitrogen from N2. An arsenic flux is used in the first eight monolayer of nitride growth to enhance nucleation of the cubic phase. Subsequent growth does not require an As flux to preserve the cubic phase. The nucleation of smooth interfaces and GaN films with low stacking fault densities is dependent upon relative concentrations of active nitrogen species in the plasma and on the nitrogen to gallium flux ratio.

Drummond, Timothy J.; Hafich, Michael J.; Heller, Edwin J.; Lee, Stephen R.; Liliental-Weber, Zuzanna; Ruvimov, Sergei; Sullivan, John P.

1999-05-03T23:59:59.000Z

93

Effect of substrate temperature on microstructure of epitaxial ZnO films grown on sapphire by sputtering  

SciTech Connect (OSTI)

The microstructure of epitaxial ZnO films on (0001) sapphire substrates deposited by reactive sputtering in substrate temperature (T{sub s}) range of 100 - 500 deg. C were investigated by High-resolution X-ray diffraction. The studies show the presence of a strained 2D layer along with 3D crystallites at low T{sub s}, whereas 3D growth is dominant at higher T{sub s}, resulting in formation of mosaic structure with lesser point and line defects.

Singh, D.; Kumar, R.; Ganguli, Tapas; Srinivasa, R. S.; Major, S. S. [Center for Research in Nano-Technology and Science (India); TRRCAT, Indore-452013 (India); Department of Metallurgical Engineering and Materials, Science (India); Department of Physics, Indian Institute of Technology Bombay, Mumbai - 400076 (India)

2012-06-05T23:59:59.000Z

94

Quantitative LEED analysis of the surface structure of a MgCl2thin film grown on Pd(111)  

SciTech Connect (OSTI)

An epitaxial, ultrathin single-crystal film (12 Angstrom) of MgCl[2] was deposited molecularly onto a Pd single crystal of (111) orientation at a crystal temperature of {approx}650 K. A detailed surface structure determination of this insulating film was performed by low-energy electron diffraction (LEED). A low incident LEED beam current (0.36 mu A) was employed to minimize the electron-stimulated desorption (ESD) of Cl. The best-fit model for the observed hexagonal MgCl[2](1 x 1) pattern corresponds to the unreconstructed (0001) Cl-terminated plane of alpha-MgCl[2], whose stacking sequence is Cl-Mg-Cl-Cl-Mg-Cl..., with a Pendry R-factor of 0.317. Small relaxations of the surface were found as 0.03 +- 0.03, 0,003 +-0.04 and 0.04 +- 0.08 Angstrom expansions of the first three Mg-Cl interlayer spacings, respectively, and a 0.10 +- 0.06 A contraction of the first Cl-Cl interlayer spacing. These small deviations were probably driven by the loss of the van der Waals interaction at the termination plane, since surface structure data for transition-metal dichalcogenides, which have different intralayer bonding, but the same intertrilayer bonding, report a similar magnitude of interlayer spacing deviations as seen in MgCl[2].

Roberts, J.G.; Gierer, M.; Fairbrother, D.H.; Van Hove, M.A.; Somorjai, G.A.

1997-08-01T23:59:59.000Z

95

Effects of H2 ambient annealing in fully 0 0 2-textured ZnO:Ga thin films grown on glass substrates using RF magnetron co-sputter deposition  

Science Journals Connector (OSTI)

Gallium doped zinc oxide (ZnO:Ga) thin films were grown on glass substrates using RF magnetron co-sputtering, followed by H2 ambient annealing at 623 K to explore a possibility of steady and low-cost process for fabricating transparent electrodes. While it was observed that the ZnO:Ga thin films were densely packed c-axis oriented self-textured structures, in the as-deposited state, the films contained Ga2O3 and ZnGa2O4 which had adverse effect on the electrical properties. On the other hand, post-annealing in H2 ambient improved the electrical properties significantly via reduction of Ga2O3 and ZnGa2O4 to release elemental Ga which subsequently acted as substitutional dopant increasing the carrier concentration by two orders of magnitude. Transmittance of the ZnO:Ga thin films were all over 90% that of glass while the optical band gap varied in accordance with the carrier concentrations due to changes in Fermi level. Experimental observation in this study suggests that transparent conductive oxide (TCO) films based on Ga doped ZnO with good electrical and optical properties can be realized via simple low-cost process.

Sungyeon Kim; Jungmok Seo; Hyeon Woo Jang; Jungsik Bang; Woong Lee; Taeyoon Lee; Jae-Min Myoung

2009-01-01T23:59:59.000Z

96

GaN High Power Devices  

SciTech Connect (OSTI)

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

97

Neutron-transmuted carbon-14 in neutron-irradiated GaN: Compensation of DX-like center  

SciTech Connect (OSTI)

The transmuted-C related luminescence and net carrier concentration are studied by combining photoluminescence, liquid scintillation, and Raman scattering. GaN single crystal films grown by metalorganic-vapor-phase epitaxy are irradiated with fast and thermal neutrons at fluxes of 3.9 × 10{sup 13} cm{sup ?2}s{sup ?1} and 8.15 × 10{sup 13} cm{sup ?2}s{sup ?1}, respectively. Irradiation time is 48 hours. The calculated {sup 72}Ge and {sup 14}C concentrations are 1.24 × 10{sup 18} cm{sup ?3} and 1.13 × 10{sup 18} cm{sup ?3}, respectively. The transmuted {sup 14}C is detected by the liquid scintillation method to survey ?-rays emitted in the process of {sup 14}C decays from {sup 14}N. Tritium ({sup 3}H) is also emitted by a (n,t) reaction of {sup 14}N due to the neutron irradiation above 4.5 MeV. Photoluminescence relating to C, DX-like center of Ge and yellow luminescence band are observed in 1000 °C annealed NTD-GaN. The free electron concentration estimated from Raman scattering is 4.97 × 10{sup 17} cm{sup ?3}. This value is lower than that from the transmuted Ge concentration, suggesting the compensation due to the transmuted {sup 14}C acceptors.

Ida, T.; Oga, T.; Kuriyama, K. [College of Engineering and Research Center of Ion Beam Technology, Hosei University Koganei, Tokyo 184-8584 (Japan); Kushida, K. [Departments of Arts and Sciences, Osaka Kyoiku University Kashiwara, Osaka 582-8582 (Japan); Xu, Q.; Fukutani, S. [Research Reactor Institute, Kyoto University Kumatori, Osaka 590-0494 (Japan)

2013-12-04T23:59:59.000Z

98

Electronic and crystalline structures of zero band-gap LuPdBi thin films grown epitaxially on MgO(100)  

SciTech Connect (OSTI)

Thin films of the proposed topological insulator LuPdBi-a Heusler compound with the C1{sub b} structure-were prepared on Ta-Mo-buffered MgO(100) substrates by co-sputtering from PdBi{sub 2} and Lu targets. Epitaxial growth of LuPdBi films was confirmed by X-ray diffraction and reflection high-energy electron diffraction. The root-mean-square roughness of the films was as low as 1.45 nm, even though the films were deposited at high temperature. The film composition is close to the ideal stoichiometric ratio. The valence band spectra of the LuPdBi films, observed by hard X-ray photoelectron spectroscopy, correspond very well with the ab initio-calculated density of states.

Shan, Rong [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany) [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); IBM Almaden Research Center, San Jose, California 95120 (United States); Ouardi, Siham; Fecher, Gerhard H.; ViolBarbosa, Carlos E.; Felser, Claudia [Max Planck Institute for Chemical Physics of Solids, 01187 Dresden (Germany)] [Max Planck Institute for Chemical Physics of Solids, 01187 Dresden (Germany); Gao, Li; Kellock, Andrew; Roche, Kevin P.; Samant, Mahesh G.; Parkin, Stuart S. P. [IBM Almaden Research Center, San Jose, California 95120 (United States)] [IBM Almaden Research Center, San Jose, California 95120 (United States); Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo 679-5198 (Japan)] [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo 679-5198 (Japan)

2013-04-29T23:59:59.000Z

99

Effects of air annealing on CdS quantum dots thin film grown at room temperature by CBD technique intended for photosensor applications  

SciTech Connect (OSTI)

Graphical abstract: The effect of different intensities (40, 60 100 and 200 W) of light on CdS quantum dots thin film annealed at 350 °C indicating enhancement in (a) photo-current and (b) photosensitivity. Highlights: ? The preparation of CdS nanodot thin film at room temperature by M-CBD technique. ? Study of air annealing on prepared CdS nanodots thin film. ? The optimized annealing temperature for CdS nanodot thin film is 350 °C. ? Modified CdS thin films can be used in photosensor application. -- Abstract: CdS quantum dots thin-films have been deposited onto the glass substrate at room temperature using modified chemical bath deposition technique. The prepared thin films were further annealed in air atmosphere at 150, 250 and 350 °C for 1 h and subsequently characterized by scanning electron microscopy, ultraviolet–visible spectroscopy, electrical resistivity and I–V system. The modifications observed in morphology and opto-electrical properties of the thin films are presented.

Shaikh, Shaheed U.; Desale, Dipalee J.; Siddiqui, Farha Y.; Ghosh, Arindam; Birajadar, Ravikiran B. [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, M.S. (India)] [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, M.S. (India); Ghule, Anil V. [Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, M.S. (India)] [Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, M.S. (India); Sharma, Ramphal, E-mail: ramphalsharma@yahoo.com [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, M.S. (India)] [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, M.S. (India)

2012-11-15T23:59:59.000Z

100

Dielectric properties of c-axis oriented Zn{sub 1-x}Mg{sub x}O thin films grown by multimagnetron sputtering  

SciTech Connect (OSTI)

Zn{sub 1-x}Mg{sub x}O (x=0.3) thin films have been fabricated on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates using multimagnetron sputtering technique. The films with wurtzite structure showed a (002) preferred orientation. Ferroelectricity in Zn{sub 1-x}Mg{sub x}O films was established from the temperature dependent dielectric constant and the polarization hysteresis loop. The temperature dependent study of dielectric constant at different frequencies exhibited a dielectric anomaly at 110 deg. C. The resistivity versus temperature characteristics showed an anomalous increase in the vicinity of the dielectric transition temperature. The Zn{sub 1-x}Mg{sub x}O thin films exhibit well-defined polarization hysteresis loop, with a remanent polarization of 0.2 {mu}C/cm{sup 2} and coercive field of 8 kV/cm at room temperature.

Dhananjay,; Krupanidhi, S. B. [Department of Instrumentation, Indian Institute of Science, Bangalore 560012 (India); Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

2006-08-21T23:59:59.000Z

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101

Epitaxial Ba{sub 2}IrO{sub 4} thin-films grown on SrTiO{sub 3} substrates by pulsed laser deposition  

SciTech Connect (OSTI)

We have synthesized epitaxial Ba{sub 2}IrO{sub 4} (BIO) thin-films on SrTiO{sub 3} (001) substrates by pulsed laser deposition and studied their electronic structure by dc-transport and optical spectroscopic experiments. We have observed that BIO thin-films are insulating but close to the metal-insulator transition boundary with significantly smaller transport and optical gap energies than its sister compound, Sr{sub 2}IrO{sub 4}. Moreover, BIO thin-films have both an enhanced electronic bandwidth and electronic-correlation energy. Our results suggest that BIO thin-films have great potential for realizing the interesting physical properties predicted in layered iridates.

Nichols, J., E-mail: john.nichols@uky.edu; Korneta, O. B.; Terzic, J.; Cao, G.; Brill, J. W.; Seo, S. S. A. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)

2014-03-24T23:59:59.000Z

102

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.

103

Structure and magnetism in strained Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy  

SciTech Connect (OSTI)

In this letter, we study the structural and magnetic properties of Ge{sub 1-x-y}Sn{sub x}Mn{sub y} films grown on Ge(001) by low temperature molecular beam epitaxy using X-ray diffraction, high resolution transmission electron microscopy, and superconducting quantum interference device. Like in Mn doped Ge films, Mn atoms diffuse during the growth and aggregate into vertically aligned Mn-rich nanocolumns of a few nanometers in diameter. Transmission electron microscopy observations in plane view clearly indicate that the Sn incorporation is not uniform with concentration in Mn rich vertical nanocolumns lower than the detection limit of electron energy loss spectroscopy. The matrix exhibits a GeSn solid solution while there is a Sn-rich GeSn shell around GeMn nanocolumns. The magnetization in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} layers is higher than in Ge{sub 1-x}Mn{sub x} films. This magnetic moment enhancement in Ge{sub 1-x-y}Sn{sub x}Mn{sub y} is probably related to the modification of the electronic structure of Mn atoms in the nanocolumns by the Sn-rich shell, which is formed around the nanocolumns.

Prestat, E. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Karlsruher Institut fuer Technologie (KIT), Laboratorium fuer Elektronenmikroskopie, D-76128 Karlsruhe (Germany); Barski, A.; Bellet-Amalric, E.; Morel, R.; Tainoff, D.; Jain, A.; Porret, C.; Bayle-Guillemaud, P.; Jamet, M. [INAC, SP2M, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Jacquot, J.-F. [INAC, SCIB, CEA and Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

2013-07-01T23:59:59.000Z

104

Deposition and characterization of Cd{sub 1?x}Mg{sub x}Te thin films grown by a novel cosublimation method  

SciTech Connect (OSTI)

Photovoltaic cells utilizing the CdS/CdTe structure have improved substantially in the past few years. Despite the recent advances, the efficiency of CdS/CdTe cells is still significantly below their Shockley–Queisser limit. CdTe based ternary alloy thin films, such as Cd{sub 1?x}Mg{sub x}Te (CMT), could be used to improve efficiency of CdS/CdTe photovoltaic cells. Higher band gap Cd{sub 1?x}Mg{sub x}Te films can be the absorber in top cells of a tandem structure or an electron reflector layer in CdS/CdTe cells. A novel cosublimation method to deposit CMT thin films has been developed. This method can deposit CMT films of band gaps ranging from 1.5 to 2.3?eV. The cosublimation method is fast, repeatable, and scalable for large areas, making it suitable for implementing into large-scale manufacturing. Characterization of as-deposited CMT films, with x varying from 0 to 0.35, reveals a linear relationship between Mg content measured by energy dispersive x-ray spectroscopy and the optical band gap. Glancing angle x-ray diffraction (GAXRD) measurements of Cd{sub 1?x}Mg{sub x}Te films show a zinc-blende structure similar to CdTe. Furthermore, increasing Mg content decreases the lattice parameter and the grain size. GAXRD shows the films are under mild tension after deposition.

Kobyakov, Pavel S., E-mail: pskobyak@rams.colostate.edu; Swanson, Drew E.; Sampath, Walajabad S. [Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, Colorado 80523 (United States); Moore, Andrew; Raguse, John M. [Department of Physics, Colorado State University, 1875 Campus Delivery, Fort Collins, Colorado 80523 (United States)

2014-03-15T23:59:59.000Z

105

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

SciTech Connect (OSTI)

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

David, Aurelien

2012-10-15T23:59:59.000Z

106

Phase Transitions and High-Voltage Electrochemical Behavior of LiCoO2 Thin Films Grown by Pulsed Laser Deposition  

E-Print Network [OSTI]

Laser Deposition H. Xia,a L. Lu,b,z Y. S. Meng,c and G. Cederc, * a Advanced Materials for Micro behavior of LiCoO2 thin-film cathodes prepared by pulsed laser deposition are studied for charging voltages- discharge curves. Ex situ X-ray diffraction measurements confirm structural changes and a phase transition

Ceder, Gerbrand

107

Film properties of low temperature HfO{sub 2} grown with H{sub 2}O, O{sub 3}, or remote O{sub 2}-plasma  

SciTech Connect (OSTI)

A reduction of the deposition temperature is necessary for atomic layer deposition (ALD) on organic devices. HfO{sub 2} films were deposited by ALD on silicon substrates in a wide temperature range from 80 to 300?°C with tetrakis[ethylmethylamino]hafnium as metal precursor and H{sub 2}O, O{sub 3}, or an remote O{sub 2}-plasma as oxygen source. Growth rate and density were correlated to electrical properties like dielectric constant and leakage current of simple capacitor structures to evaluate the impact of different process conditions. Process optimizations were performed to reduce film imperfections visible at lower deposition temperatures. Additionally, the influence of postdeposition annealing on the structural and electrical properties was studied.

Richter, Claudia, E-mail: Claudia.Richter@namlab.com; Schenk, Tony; Schroeder, Uwe [NaMLab gGmbH, Noethnitzerstr. 64, 01187 Dresden (Germany); Mikolajick, Thomas [NaMLab gGmbH, Noethnitzerstr. 64, 01187 Dresden, Germany and Institut für Halbleiter und Mikrosystemtechnik, TU Dresden, Noethnitzerstr. 64, 01187 Dresden (Germany)

2014-01-15T23:59:59.000Z

108

Doping and isolation of GaN, InGaN and InAlN using ion implantation  

SciTech Connect (OSTI)

Both n- and p-type doping have been achieved in GaN using Si{sup +} or Mg{sup +}/P{sup +} implantation, respectively, followed annealing at {ge} 1050{degrees}C. Using proximity rapid thermal annealing (10sec) the GaN surface retains both smooth morphology and its original stoichiometry. Variable temperature Hall measurements reveal approximate energy levels of 62meV for the implanted Si and 171meV for the Mg, which are similar to their values in epitaxially grown GaN. Implant isolation of both n- and p-type GaN, and n-type In{sub 0.75}Al{sub 0.25}N with multiple energy inert species (e.g. N{sup +} or F{sup +}) produces high resistivity ({ge}10{sup 8}{omega}/{open_square}) after subsequent annealing in the range 600-700{degrees}C. Smaller increases in sheet resistance are observed for In{sub x}Ga{sup 1-x}N (x=0.33-0.75) under the same conditions due to the smaller energy bandgaps and the shallower energy levels of the damage-related states controlling the resistivity.

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

1995-08-01T23:59:59.000Z

109

Polarity determination for MOCVD growth of GaN on Si(111) by convergent beam electron diffraction[Metal Organic Chemical Vapor Deposition  

SciTech Connect (OSTI)

The polarity of laterally epitaxially overgrown (LEO) GaN on Si(111) with an AlN buffer layer grown by MOCVD has been studied by convergent beam electron diffraction (CBED). The LEO GaN was studied by cross-section and plan-view transmission electron microscopy (TEM). The threading dislocation density is less than 10{sup 8} cm{sup {minus}2} and no inversion domains were observed. CBED patterns were obtained at 200 kV for the <1 {bar 1} 00> zone. Simulation was done by many-beam solution with 33 zero-order beams. The comparison of experimental CBED patterns and simulated patterns indicates that the polarity of GaN on Si(111) is Ga face.

Zhao, L.; Marchand, H.; Fini, P.; Denbaars, S.P.; Mishra, U.K.; Speck, J.S.

2000-07-01T23:59:59.000Z

110

Effect of the nitrogen ion energy on the MBE growth of thin gallium nitride films  

Science Journals Connector (OSTI)

The influence of the energy of bombarding nitrogen ions on the growth of thin gallium nitride (GaN) films under molecular beam epitaxy (MBE) conditions has been simulated using the method of balance kinetic eq...

D. V. Kulikov; Yu. V. Trushin; V. S. Kharlamov

2010-03-01T23:59:59.000Z

111

Second harmonic generation from Ge doped SiO{sub 2} (Ge{sub x}(SiO{sub 2}){sub 1?x}) thin films grown by sputtering  

SciTech Connect (OSTI)

Second-order nonlinear optical properties of sputter-deposited Ge-doped SiO{sub 2} thin films were investigated. It was shown that the second-order nonlinearity of SiO{sub 2}, which vanishes in the electric-dipole approximation due to the centrosymmetric structure, can be significantly enhanced by Ge doping. The observed maximum value of d{sub 33} was 8.2 pm/V, which is 4 times larger than d{sub 22} of ?-BaB{sub 2}O{sub 4} crystal. Strong correlation was observed between the d{sub eff} values and the electron spin resonance signals arising from GeP{sub b} centers, suggesting that GeP{sub b} centers are the most probable origin of the large second-order nonlinearity.

Kawamura, Ibuki; Imakita, Kenji; Fujii, Minoru; Hayashi, Shinji [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan)] [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan)

2013-11-11T23:59:59.000Z

112

Use of reflectance spectroscopy for in-situ monitoring of InP/InGaAsP films grown by MOVPE  

SciTech Connect (OSTI)

The authors report the first use of in-situ reflectance spectroscopy for real-time monitoring of the epitaxial growth of InP/InGaAsP films. Optical monitoring of this materials system has been limited by the strong absorption of InP/InGaAsP in the spectral range of commonly available Si-based array detectors ({lambda}{approximately}400--1,100 nm). In this work a Si/PbS dual detector arrangement, with a wavelength range 400--2,500 nm, and a grating spectrometer were used to acquire spectral data beyond the absorption regions of InP and InGaAsP. The quartz MOVPE reactor was modified with a simple optical viewport for acquisition of normal incidence reflectance spectra. Data were obtained on InP/InGaAs heterostructures, 1.55 {micro}m InP/InGaAsP Bragg stacks, and 1.3 {micro}m InGaAsP MQW laser structures.

Lum, R.M.; McDonald, M.L.; Bean, J.C.; Vandenberg, J.; Pernell, T.L.; Chu, S.N.G. [Bell Labs., Murray Hill, NJ (United States); Robertson, A.; Karp, A. [Bell Labs., Princeton, NJ (United States). Engineering Research Center

1996-12-31T23:59:59.000Z

113

Anisotropy of effective electron masses in highly doped nonpolar GaN  

SciTech Connect (OSTI)

The anisotropic effective electron masses in wurtzite GaN are determined by generalized infrared spectroscopic ellipsometry. Nonpolar (112{sup ¯}0) oriented thin films allow accessing both effective masses, m{sub ?}{sup *} and m{sub ?}{sup *}, by determining the screened plasma frequencies. A n-type doping range up to 1.7?×?10{sup 20}?cm{sup ?3} is investigated. The effective mass ratio m{sub ?}{sup *}/m{sub ?}{sup *} is obtained with highest accuracy and is found to be 1.11 independent on electron concentration up to 1.2?×?10{sup 20}?cm{sup ?3}. For higher electron concentrations, the conduction band non-parabolicity is mirrored in changes. Absolute values for effective electron masses depend on additional input of carrier concentrations determined by Hall effect measurements. We obtain m{sub ?}{sup *}=(0.239±0.004)m{sub 0} and m{sub ?}{sup *}=(0.216±0.003)m{sub 0} for the parabolic range of the GaN conduction band. Our data are indication of a parabolic GaN conduction band up to an energy of approximately 400?meV above the conduction band minimum.

Feneberg, Martin, E-mail: martin.feneberg@ovgu.de; Lange, Karsten; Lidig, Christian; Wieneke, Matthias; Witte, Hartmut; Bläsing, Jürgen; Dadgar, Armin; Krost, Alois; Goldhahn, Rüdiger [Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg (Germany)] [Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg (Germany)

2013-12-02T23:59:59.000Z

114

Structural and optical properties of InGaN–GaN nanowire heterostructures grown by molecular beam epitaxy  

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

InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaN to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, ?-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.

Limbach, F. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Gotschke, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Stoica, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Calarco, R. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Sutter, E. [Brookhaven National Lab., Upton, NY (United States); Ciston, J. [Brookhaven National Lab., Upton, NY (United States); Cusco, R. [Consell Superior d'Investigacions Cientifiques (CSIC), Barcelona (Spain); Artus, L. [Consell Superior d'Investigacions Cientifiques (CSIC), Barcelona (Spain); Kremling, S. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Hofling, S. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Worschech, L. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Grutzmacher, D. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany)

2011-01-07T23:59:59.000Z

115

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

E-Print Network [OSTI]

73, 1691 (1998). 11. H. Marchand, J.P. Ibbetson, P.T. Fini,1999). 17. P. Fini, H. Marchand, J.P. Ibbetson, B. Moran, L.

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

2006-01-01T23:59:59.000Z

116

GaN quantum dot superlattices grown by molecular beam epitaxy at high temperature  

E-Print Network [OSTI]

P-based optoelectronic devices with Si microelectronic devices. This method uses a Au-Ge eutectic alloy as the bonding. The realization of integrafion of GaAs- and InP-based optoelectronic devices with Si microelectronic components

117

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

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

Melting Behavior of GaN Nanotubes. Atomic-Level Study of Melting Behavior of GaN Nanotubes. Abstract: Molecular dynamics simulations with a Stillinger-Weber potential have been...

118

E-Print Network 3.0 - aln gan inn Sample Search Results  

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

Summary: size. Introduction GaN and its alloys with InN and AlN have been used for optoelectronic devices... region. The formation of self-assembled GaN nanostructures on aluminum...

119

Investigations of chemical vapor deposition of GaN using synchrotron radiation  

SciTech Connect (OSTI)

The authors apply synchrotron x-ray analysis techniques to probe the surface structure of GaN films during synthesis by metal-organic chemical vapor deposition (MOCVD). Their approach is to observe the evolution of surface structure and morphology in real time using grazing incidence x-ray scattering (GIXS). This technique combines the ability of x-rays to penetrate the chemical vapor deposition environment for in situ measurements, with the sensitivity of GIXS to atomic scale structure. In this paper they present examples from some of their studies of growth modes and surface evolution as a function of process conditions that illustrate the capabilities of synchrotron x-ray analysis during MOCVD growth. They focus on studies of the homoepitaxial growth mode, island coarsening dynamics, and effects of impurities.

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

2000-05-25T23:59:59.000Z

120

K.K. Gan EPS 2001 1 New Results on Charm  

E-Print Network [OSTI]

K.K. Gan EPS 2001 1 New Results on Charm Semileptonic Decays and Lifetime K.K. Gan The Ohio State University July 14, 2001 Representing CLEO Collaboration #12;K.K. Gan EPS 2001 2 l measurement of l first+ B(D+ K* 0 l+ l ) (D*+ ) c + #12;K.K. Gan EPS 2001 3 l P measurement of form factors helps to guide

Gan, K. K.

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121

Joint ATLAS/CMS SLHC Opto WG 1 K.K. Gan Lesson Learned from  

E-Print Network [OSTI]

Joint ATLAS/CMS SLHC Opto WG 1 K.K. Gan Lesson Learned from ATLAS Pixel Optical Link #12;Joint ATLAS/CMS SLHC Opto WG 2 Outline Introduction VCSEL/PIN monitoring Analysis of opto-board/VCSEL/PIN failures Summary K.K. Gan #12;K.K. Gan Joint ATLAS/CMS SLHC Opto WG 3 Introduction Architecture

Gan, K. K.

122

K.K. Gan ATLAS Tracker Upgrade Workshop 1 Progress Report on Joint ATLAS/CMS  

E-Print Network [OSTI]

K.K. Gan ATLAS Tracker Upgrade Workshop 1 Progress Report on Joint ATLAS/CMS SLHC Opto ATLAS Tracker Upgrade Workshop 2 Outline Introduction Subgroups activities Summary #12;K.K. Gan ATLAS System #12;K.K. Gan ATLAS Tracker Upgrade Workshop 4 Group A: Lesson Learned and to be Learned from LHC

Gan, K. K.

123

Counting molecular-beam grown graphene layers  

SciTech Connect (OSTI)

We have used the ratio of the integrated intensity of graphene's Raman G peak to that of the silicon substrate's first-order optical phonon peak, accurately to determine the number of graphene layers across our molecular-beam (MB) grown graphene films. We find that these results agree well both, with those from our own exfoliated single and few-layer graphene flakes, and with the results of Koh et al.[ACS Nano 5, 269 (2011)]. We hence distinguish regions of single-, bi-, tri-, four-layer, etc., graphene, consecutively, as we scan coarsely across our MB-grown graphene. This is the first, but crucial, step to being able to grow, by such molecular-beam-techniques, a specified number of large-area graphene layers, to order.

Plaut, Annette S. [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom)] [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Wurstbauer, Ulrich [Department of Physics, Columbia University, New York, New York 10027 (United States)] [Department of Physics, Columbia University, New York, New York 10027 (United States); Pinczuk, Aron [Department of Physics, Columbia University, New York, New York 10027 (United States) [Department of Physics, Columbia University, New York, New York 10027 (United States); Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Garcia, Jorge M. [MBE Lab, IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Madrid, E-28760 (Spain)] [MBE Lab, IMM-Instituto de Microelectronica de Madrid (CNM-CSIC), Madrid, E-28760 (Spain); Pfeiffer, Loren N. [Electrical Engineering Department, Princeton University, New Jersey 08544 (United States)] [Electrical Engineering Department, Princeton University, New Jersey 08544 (United States)

2013-06-17T23:59:59.000Z

124

Low temperature grown polycrystalline La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films on amorphous SiO{sub 2} substrates by rf magnetron sputtering  

SciTech Connect (OSTI)

The La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films have been prepared on amorphous SiO{sub 2} substrates by a rf magnetron sputtering technique under various oxygen flow rates and rf powers at a relatively low substrate temperature of 350 deg. C. The effects of oxygen flow rate and rf power on their physical properties were systematically investigated. X-ray diffraction results show that the growth orientation and crystallinity of the films were affected by rf power and oxygen flow rate. The electrical resistivity of the films was reduced with increasing oxygen flow rate and rf power due to enhanced {l_brace}100{r_brace} growth plane orientation and enlarged grain size of the films. In addition, a relatively high temperature coefficient of resistance value of -2.4% was obtained in the present investigation even with low deposition temperature.

Choi, Sun Gyu; Sivasankar Reddy, A.; Park, Hyung-Ho; Yang, Woo Seok; Ryu, Hojun; Yu, Byoung-Gon [Department of Materials Science and Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-ku, Seoul 120-749 (Korea, Republic of); Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of)

2009-07-15T23:59:59.000Z

125

Maskless lateral epitaxial overgrowth of GaN on sapphire  

SciTech Connect (OSTI)

The authors demonstrate a technique of lateral epitaxial overgrowth (LEO) of GaN, termed maskless LEO, in which no mask is deposited prior to LEO regrowth. Instead, a bulk (> 2 {micro}m) GaN layer on sapphire is selectively dry etched, leaving {approximately} 5 {micro}m-wide stripe mesas oriented in the <10{bar 1}0>{sub GaN} direction, with a 20 {micro}m period. These stripes serve as seeds for LEO GaN growth, which proceeds from the tops of the stripes and expands laterally, resulting in a T, or overhang, morphology. As for LEO over an SiO{sub 2} mask, significant defect reduction (from {approximately} 10{sup 9} cm{sup {minus}2} to {approximately} 10{sup 6} cm{sup {minus}2}) is observed in cross-sectional transmission electron microscopy (TEM). Atomic force microscopy of the top surface of the LEO GaN reveals that no threading dislocations with screw component terminate at the surfaces of laterally overgrown regions. X-ray diffraction measurements reveal that the wings exhibit a crystallographic tilt away from the seed regions in an azimuth perpendicular to the stripe direction; the tilt angle ({approximately} 0.4--0.5{degree}) is relatively independent of growth temperature and wing aspect ratio.

Fini, P.; Marchand, H.; Ibbetson, J.P.; Moran, B.; Zhao, L.; Denbaars, S.P.; Speck, J.S.; Mishra, U.K.

1999-07-01T23:59:59.000Z

126

Ion beam sputter etching of galliumnitride grown by chloride transport LP–CVD  

Science Journals Connector (OSTI)

Galliumnitrid (GaN) layers, grown by chloride transport LP–CVD, were etched by ion beam sputtering with carbon dioxide (CO2). Before etching all samples were masked by electron beam evaporated titanium. We report on the dependence of the etch rate on the angle of incidence of the ion beam. Furthermore we present structural examinations of the surface before and after ion etching as well as an analysis of masking effects. Surface roughening and structural defects were investigated by optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Michael Topf; Fehmi Cavas; Bruno K Meyer; Bertilo Kempf; Walter Betz; Peter Veit

1999-01-01T23:59:59.000Z

127

Determination of crystallographic orientation of lead-free piezoelectric (K,Na)NbO{sub 3} epitaxial thin films grown on SrTiO{sub 3} (100) surfaces  

SciTech Connect (OSTI)

Crystallographic structure of sol-gel-processed lead-free (K,Na)NbO{sub 3} (KNN) epitaxial films on [100]-cut SrTiO{sub 3} single-crystalline substrates was investigated for a deeper understanding of its piezoelectric response. Lattice parameter measurement by high-resolution X-ray diffraction and transmission electron microscopy revealed that the orthorhombic KNN films on SrTiO{sub 3} (100) surfaces are [010] oriented (b-axis-oriented) rather than commonly identified c-axis orientation. Based on the crystallographic orientation and corresponding ferroelectric domain structure investigated by piezoresponse force microscopy, the superior piezoelectric property along b-axis of epitaxial KNN films than other orientations can be explained.

Yu, Qi; Zhu, Fang-Yuan; Cheng, Li-Qian; Wang, Ke; Li, Jing-Feng, E-mail: jingfeng@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084 Beijing (China)] [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084 Beijing (China)

2014-03-10T23:59:59.000Z

128

Strain relief and AlSb buffer layer morphology in GaSb heteroepitaxial films grown on Si as revealed by high-angle annular dark-field scanning transmission electron microscopy  

SciTech Connect (OSTI)

The interfacial misfit (IMF) dislocation array of an epitaxial GaSb film on a Si substrate has been imaged with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The mismatch strain accommodation through dislocation formation has been investigated using geometric phase analysis (GPA) on HAADF-STEM images with atomic resolution to probe the defects' local strain distribution. These measurements indicate that the lattice parameter of the epitaxial film recovers its bulk value within three unit cells from the interface due to the relaxation through IMF dislocations. The atomic number contrast of the HAADF-STEM images and energy dispersive x-ray spectrometry illustrate the formation of islands of AlSb buffer layer along the interface. The role of the AlSb buffer layer in facilitating the GaSb film growth on Si is further elucidated by investigating the strain field of the islands with the GPA.

Vajargah, S. Hosseini; Couillard, M.; Cui, K. [Department of Material Science and Engineering, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4M1 (Canada); Tavakoli, S. Ghanad; Robinson, B.; Kleiman, R. N.; Preston, J. S. [Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Botton, G. A. [Department of Material Science and Engineering, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4M1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

2011-02-21T23:59:59.000Z

129

Highly mismatched crystalline and amorphous GaN(1-x)As(x) alloys in the whole composition range  

SciTech Connect (OSTI)

Alloying is a commonly accepted method to tailor properties of semiconductor materials for specific applications. Only a limited number of semiconductor alloys can be easily synthesized in the full composition range. Such alloys are, in general, formed of component elements that are well matched in terms of ionicity, atom size, and electronegativity. In contrast there is a broad class of potential semiconductor alloys formed of component materials with distinctly different properties. In most instances these mismatched alloys are immiscible under standard growth conditions. Here we report on the properties of GaN1-xAsx, a highly mismatched, immiscible alloy system that was successfully synthesized in the whole composition range using a nonequilibrium low temperature molecular beam epitaxy technique. The alloys are amorphous in the composition range of 0.17films have smooth morphology, homogeneous composition, and sharp, well defined optical absorption edges. The band gap energy varies in a broad energy range from ~;;3.4 eV in GaN to ~;;0.8 eV at x~;;0.85. The reduction in the band gap can be attributed primarily to the downward movement of the conduction band for alloys with x>0.2, and to the upward movement of the valence band for alloys with x<0.2. The unique features of the band structure offer an opportunity of using GaN1-xAsx alloys for various types of solar power conversion devices.

Yu, K. M.; Novikov, S. V.; Broesler, R.; Demchenko, I. N.; Denlinger, J. D.; Liliental-Weber, Z.; Luckert, F.; Martin, R. W.; Walukiewicz, W.; Foxon, C. T.

2009-08-29T23:59:59.000Z

130

Scanned probe characterization of semiconductor nanostructures  

E-Print Network [OSTI]

of the window and wing region of the a–plane GaN film,? m thick GaN film was then grown through the windows in thewindow regions, lateral overgrowth over the dielectric mask, and coalescence of the film

Law, James Jeremy MacDonald

2009-01-01T23:59:59.000Z

131

Strong circular photogalvanic effect in ZnO epitaxial films  

SciTech Connect (OSTI)

A strong circular photogalvanic effect (CPGE) in ZnO epitaxial films was reported under interband excitation. It was observed that CPGE current is as large as 100 nA/W in ZnO, which is about one order in magnitude higher than that in InN film while the CPGE currents in GaN films are not detectable. The possible reasons for the above observations are the strong spin orbit coupling in ZnO or the inversed valence band structure of ZnO.

Zhang, Q.; Wang, X. Q.; Yin, C. M.; Shen, B. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Chen, Y. H.; Chang, K. [Laboratory of Semiconductor Materials Science, Institute of Semiconductors, CAS, Beijing 100083 (China); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)

2011-12-23T23:59:59.000Z

132

Structural Properties of Eu-Doped GaN Investigated by Raman Spectroscopy  

SciTech Connect (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

133

Synthesis and Structure of Sr3GaN3 and Sr6GaN5:? Strontium Gallium Nitrides with Isolated Planar [GaN3]6- Anions  

Science Journals Connector (OSTI)

Synthesis and Structure of Sr3GaN3 and Sr6GaN5:? Strontium Gallium Nitrides with Isolated Planar [GaN3]6- Anions ... 9-19 In most cases, an alkaline earth metal is introduced into a Na melt to enhance the solubility of nitrogen, and is incorporated in the nitride product. ... The container was sealed by welding its open end in an argon atmosphere with active water-cooling so that NaN3 did not decompose due to heating during the welding. ...

Dong Gon Park; Zoltán A. Gál; Francis J. DiSalvo

2003-02-13T23:59:59.000Z

134

Dynamic Model of Hydrogen in GaN  

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

135

Excitation mechanism and thermal emission quenching of Tb ions in silicon rich silicon oxide thin films grown by plasma-enhanced chemical vapour deposition—Do we need silicon nanoclusters?  

SciTech Connect (OSTI)

In this work, we will discuss the excitation and emission properties of Tb ions in a Silicon Rich Silicon Oxide (SRSO) matrix obtained at different technological conditions. By means of electron cyclotron resonance plasma-enhanced chemical vapour deposition, undoped and doped SRSO films have been obtained with different Si content (33, 35, 39, 50 at. %) and were annealed at different temperatures (600, 900, 1100?°C). The samples were characterized optically and structurally using photoluminescence (PL), PL excitation, time resolved PL, absorption, cathodoluminescence, temperature dependent PL, Rutherford backscattering spectrometry, Fourier transform infrared spectroscopy and positron annihilation lifetime spectroscopy. Based on the obtained results, we discuss how the matrix modifications influence excitation and emission properties of Tb ions.

Podhorodecki, A., E-mail: artur.p.podhorodecki@pwr.wroc.pl; Golacki, L. W.; Zatryb, G.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Wang, J.; Jadwisienczak, W. [School of EECS, Ohio University, Stocker Center 363, Athens, Ohio 45701 (United States); Fedus, K. [Institute of Physics, Nicholas Copernicus University, Grudziadzka 5/7, 87-100 Torun (Poland); Wojcik, J.; Wilson, P. R. J.; Mascher, P. [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, 1280 Main St. W, Hamilton, Ontario L8S4L7 (Canada)

2014-04-14T23:59:59.000Z

136

Metal contacts on ZnSe and GaN  

SciTech Connect (OSTI)

Recently, considerable interest has been focused on the development of blue light emitting materials and devices. The focus has been on GaN and ZnSe, direct band gap semiconductors with bands gaps of 3.4 and 2.6 eV, respectively. To have efficient, reliable devices it is necessary to have thermally and electrically stable Ohmic contacts. This requires knowledge of the metal-semiconductor reaction behavior. To date few studies have investigated this behavior. Much information has accumulated over the years on the behavior of metals on Si and GaAs. This thesis provides new knowledge for the more ionic wide band gap semiconductors. The initial reaction temperatures, first phases formed, and phase stability of Pt, Pd, and Ni on both semiconductors were investigated. The reactions of these metals on ZnSe and GaN are discussed in detail and correlated with predicted behavior. In addition, comparisons are made between these highly ionic semiconductors and Si and GaAs. The trends observed here should also be applicable to other II-VI and III-Nitride semiconductor systems, while the information on phase formation and stability should be useful in the development of contacts for ZnSe and GaN devices.

Duxstad, K.J. [Univ. of California, Berkeley, CA (United States). Materials Science and Mineral Engineering; [Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

1997-05-01T23:59:59.000Z

137

E-Print Network 3.0 - anti-reflective thin film Sample Search...  

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

Inc., Woburn, MA 01801 High quality polycrystalline diamond films grown Source: Massachusetts at Lowell, University of - Submillimeter-Wave Technology Laboratory...

138

K.K. Gan Siena02 1 The Ohio State University  

E-Print Network [OSTI]

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

Gan, K. K.

139

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

E-Print Network [OSTI]

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

Myers, Tom

140

Ceramic Thin Films: Fabrication and Applications  

Science Journals Connector (OSTI)

...SPRAYED CERAMIC COATING, JOURNAL...PB1-XCAXTIO3 THIN-FILM GROWN BY...ELECTRICAL, OPTICAL, AND ELECTRO-OPTIC...fabrication and applications. | Ceramics...controlled optical switches...Ceramic coatings ofalumina...modified by the application of mechanical...material as a thin film cannot only...successive coatings. Although...respect to CVD that the...purposes. Applications of Thin Film Ceramics...

M. Sayer; K. Sreenivas

1990-03-02T23:59:59.000Z

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

Nitrogen doped zinc oxide thin film  

SciTech Connect (OSTI)

To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, 0.3 atomic % nitrogen was found to exist in the form of N{sub 2}O and N{sub 2}. Upon annealing, N{sub 2}O decomposes into N{sub 2} and O{sub 2}. In furnace-annealed samples N{sub 2} redistributes diffusively and forms gaseous N{sub 2} bubbles in the films. Unintentionally doped ZnO films were grown at different oxygen partial pressures. Zni was found to form even at oxygen-rich condition and led to n-type conductivity. N{sup +} implantation into unintentionally doped ZnO film deteriorates the crystallinity and optical properties and leads to higher electron concentration. The free electrons in the implanted films are attributed to the defects introduced by implantation and formation of (N{sub 2}){sub O} and Zni. Although today there is still no reliable means to produce good quality, stable p-type ZnO material, ZnO remains an attractive material with potential for high performance short wavelength optoelectronic devices. One may argue that gallium nitride was in a similar situation a decade ago. Although we did not obtain any p-type conductivity, we hope our research will provide a valuable reference to the literature.

Li, Sonny X.

2003-12-15T23:59:59.000Z

142

Metalorganic chemical vapor deposition of GaN on Si(111): Stress control and application to field-effect transistors  

SciTech Connect (OSTI)

Two schemes of nucleation and growth of gallium nitride on Si(111) substrates are investigated and the structural and electrical properties of the resulting films are reported. Gallium nitride films grown using a 10{endash}500 nm-thick AlN buffer layer deposited at high temperature ({similar_to}1050{degree}C) are found to be under 260{endash}530 MPa of tensile stress and exhibit cracking, the origin of which is discussed. The threading dislocation density in these films increases with increasing AlN thickness, covering a range of 1.1 to {gt}5.8{times}10{sup 9}cm{sup {minus}2}. Films grown using a thick, AlN-to-GaN graded buffer layer are found to be under compressive stress and are completely crack free. Heterojunction field effect transistors fabricated on such films result in well-defined saturation and pinch-off behavior with a saturated current of {similar_to}525 mA/mm and a transconductance of {similar_to}100 mS/mm in dc operation. {copyright} 2001 American Institute of Physics.

Marchand, H.; Zhao, L.; Zhang, N.; Moran, B.; Coffie, R.; Mishra, U. K.; Speck, J. S.; DenBaars, S. P.; Freitas, J. A.

2001-06-15T23:59:59.000Z

143

Optical resonance modes in GaN pyramid microcavities  

SciTech Connect (OSTI)

An array of GaN hexagonal pyramids with a side length of 8.0 {mu}m was fabricated by selective epitaxial overgrowth. These microsized pyramids are highly efficient microcavities. Three types of optical resonance modes with mode spacings of 10, 5.0, and 6.0 {Angstrom} were observed when a single pyramid was pumped optically by an intense ultraviolet laser beam. An optical ray tracing method has been developed for calculating the optical resonance modes inside the pyramid microcavities. It was shown that a single pyramidal cavity can support several different types of optical resonance modes. The calculated mode spacing agrees very well with the observations. The uniqueness and advantages of this class of hexagonal pyramidal microcavities over the other microcavities are discussed. The implications of our finding on the future GaN microcavity light emitters including micro-light-emitting diodes, microcavity lasers, and vertical-cavity-surface emitting lasers are also discussed. {copyright} {ital 1999 American Institute of Physics.}

Jiang, H.X.; Lin, J.Y.; Zeng, K.C. [Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601 (United States)] [Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601 (United States); Yang, W. [Honeywell Technology Center, Plymouth, Minnesota 55441 (United States)] [Honeywell Technology Center, Plymouth, Minnesota 55441 (United States)

1999-08-01T23:59:59.000Z

144

Magnetic Skyrmion Phase in MnSi Thin Films.  

E-Print Network [OSTI]

??Detailed magnetometry and polarized neutron reflectometry studies were conducted on MnSi thin films grown epitaxially on Si(111) substrates. It is demonstrated that with an in-plane… (more)

Wilson, Murray

2013-01-01T23:59:59.000Z

145

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

E-Print Network [OSTI]

Vision, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, Uni and experimentally demonstrated that congruent sublimation of GaN is possible, which yields diatomic or polymeric

Yang, Peidong

146

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

147

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

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

and small crystalline zones that are randomly oriented. Citation: Jiang W, WJ Weber, LM Wang, and K Sun.2004."Amorphization Processes in Au Ion Irradiated GaN at 150 - 300...

148

In-situ ellipsometry: Identification of surface terminations during GaN growth , T. Schmidtling1  

E-Print Network [OSTI]

1 In-situ ellipsometry: Identification of surface terminations during GaN growth C. Cobet1 , T SE, one is not limited to any special bulk or surface symmetry for optical characterisation. In PAMBE

Feenstra, Randall

149

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

E-Print Network [OSTI]

University #12;K.K. Gan ATLAS Pixel Week 2 Outline l VDC-I5 l VDC/DORIC-I5e l QA l BeO Opto-board l Summary reset from active high to low for ease of implementation by DCS ] slightly better performance at ±3s: Engineering Run #12;K.K. Gan ATLAS Pixel Week 9 l circuit boards: designed/built/tested l LabView programs

Gan, K. K.

150

Electrical properties of MOS capacitors formed by PEALD grown Al2O3 on silicon  

Science Journals Connector (OSTI)

In the present work, we have grown 2.83 nm thin Al2O3 films directly on pre-cleaned p-Si (100) substrate using precursor Trimethyl Aluminium (TMA) with substrate temperature of 300°C in a Plasma Enhanced Atomic L...

A. M. Mahajan; A. G. Khairnar; B. J. Thibeault

2014-04-01T23:59:59.000Z

151

Characterization of metal oxide layers grown on CVD graphene  

SciTech Connect (OSTI)

Growth of a fully oxidized aluminum oxide layer with low surface roughness on graphene grown by chemical vapor deposition is demonstrated. This is accomplished by the deposition of a 0.2 nm thick titanium seed layer on the graphene prior to the deposition of the aluminum under ultra high vacuum conditions, which was subsequently oxidized. The stoichiometry and surface roughness of the oxide layers were measured for a range of titanium and aluminum depositions utilizing ex situ x-ray photoelectron spectrometry and atomic force microscopy. These fully oxidized films are expected to produce good dielectric layers for use in graphene based electronic devices.

Matsubayashi, Akitomo; Abel, Joseph; Prasad Sinha, Dhiraj; Lee, Ji Ung; LaBella, Vincent P. [College of Nanoscale Science and Engineering, University at Albany, SUNY, Albany, New York 12203 (United States)

2013-03-15T23:59:59.000Z

152

Characterization of Nanoporous WO3 Films Grown via Ballistic...  

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

different conditions on polished polycrystalline Ta and Pt(111) substrates via direct sublimation of monodispersed gas phase of cyclic (WO3)3 clusters. Scanning Electron...

153

Microstructure and properties of copper thin films on silicon substrates  

E-Print Network [OSTI]

copper thin films but on an expense of conductivity. This study proposes a technique to deposit high strength and high conductivity copper thin films on different silicon substrates at room temperature. Single crystal Cu (100) and Cu (111) have been grown...

Jain, Vibhor Vinodkumar

2009-05-15T23:59:59.000Z

154

Growth-front roughening in amorphous silicon films by sputtering T. Karabacak,* Y.-P. Zhao, G.-C. Wang, and T.-M. Lu  

E-Print Network [OSTI]

Growth-front roughening in amorphous silicon films by sputtering T. Karabacak,* Y.-P. Zhao, G industry and is a material of special interest. The dy- namic roughening of silicon thin films grown

Wang, Gwo-Ching

155

Transport properties, specific heat and thermal conductivity of GaN nanocrystalline ceramic  

SciTech Connect (OSTI)

The structural and transport properties (resistivity, thermopower and Hall effect), specific heat and thermal conductivity have been measured for GaN nanocrystalline ceramic prepared by hot pressing. It was found that the temperature dependence of resistivity in temperature range 10-300 K shows the very low activation energy, which is ascribed to the shallow donor doping originating in amorphous phase of sample. The major charge carriers are electrons, what is indicated by negative sign of Hall constant and Seebeck coefficient. The thermopower attains large values (-58 {mu}V/K at 300 K) and was characterized by linear temperature dependence which suggests the diffusion as a major contribution to Seebeck effect. The high electron concentration of 1.3x10{sup 19} cm{sup -3} and high electronic specific heat coefficient determined to be 2.4 mJ/molK{sup 2} allow to conclude that GaN ceramic demonstrates the semimetallic-like behavior accompanied by very small mobility of electrons ({approx}0.1 cm{sup 2}/V s) which is responsible for its high resistivity. A low heat conductivity of GaN ceramics is associated with partial amorphous phase of GaN grains due to high pressure sintering. - Graphical Abstract: Thermal resistivity and thermopower measurements indicates the high phonon scattering and lack of phonon-drag contribution to thermopower in GaN nanoceramics pressed under 4 GPa at 800 {sup o}C.

Sulkowski, Czeslaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); ChuchmaLa, Andrzej, E-mail: andrzej.chuchmala@pwr.wroc.p [Wroclaw University of Technology, Institute of Electrical Engineering Fundamentals (I7), Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Zaleski, Andrzej J.; Matusiak, Marcin; Mucha, Jan; GLuchowski, PaweL; Strek, WiesLaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)

2010-10-15T23:59:59.000Z

156

Direct measurement of curvature dependent ion etching of GaN Bentao Cui and P.I. Cohen  

E-Print Network [OSTI]

Direct measurement of curvature dependent ion etching of GaN Bentao Cui and P.I. Cohen Department of Electrical and Computer Engineering and Department of Chemical Engineering and Materials Science, University of nanoscale pores or dimples during ion etching of GaN was used to measure the magnitude of the curvature

Cohen, Philip I.

157

Lithium manganese oxide films fabricated by electron beam directed vapor deposition  

E-Print Network [OSTI]

material for high energy den- sity battery applications.7,8 Lithium­transition metal oxide films can.2. After annealing in air at 700 °C, thin films grown with a low jet speed had a cubic spinel structure Li/Li-ion batteries. © 2008 American Vacuum Society. DOI: 10.1116/1.2823488 I. INTRODUCTION Thin film

Wadley, Haydn

158

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

SciTech Connect (OSTI)

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

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

2014-04-24T23:59:59.000Z

159

Physical Properties of GaN Nanotubes as Revealed by Computer Simulation  

SciTech Connect (OSTI)

Single-crystalline wurtzite GaN nanotubes have been synthesized recently with proposed applications in nanoscale electronics, optoelectronics and the biochemical-sensing field. Molecular dynamics methods with a Stillinger-Weber potential are used to investigate the melting behavior, thermal conductivity and mechanical properties of these wurtzite-type single crystalline GaN nanotubes. Four major topical areas are summarized in this chapter. (1) The melting temperature of the GaN nanotubes increases with the thickness of the nanotubes to a saturation value, which is close to the melting temperature of bulk GaN. The simulations result reveal that the nanotubes begin to melt at the surface, and then the melting rapidly extends to the interior of the nanotubes as the temperature increases. (2) The thermal conductivity of nanotubes is smaller than that of the bulk GaN single crystal. The thermal conductivity is also found to decrease with temperature and increase with increasing wall thickness of the nanotubes. The change of phonon spectrum and surface inelastic scattering may account for the reduction of thermal conductivity in the nanotubes, while thermal softening and high frequency phonon interactions at high temperatures may provide an explanation for its decrease with increasing temperature. (3) At low temperatures, the simulation results show that the nanotubes exhibit brittle properties; whereas at high temperatures, they behave as ductile materials. The brittle to ductile transition temperature generally increases with increasing wall thickness of the nanotubes and increasing strain rate. (4) The simulation temperature, tube length and strain rate affect the buckling behavior of GaN nanotubes. The critical stress decreases with the increase of simulation temperature and tube length. The dependence of buckling on tube length is consistent with the analysis of equivalent continuum structures using Euler buckling theory.

Wang, Zhiguo; Gao, Fei; Zu, Xiaotao; Weber, William J.

2008-07-25T23:59:59.000Z

160

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

SciTech Connect (OSTI)

Atom probe tomography (APT) has been used to achieve three-dimensional characterization of a III-nitride laser diode (LD) structure grown by molecular beam epitaxy (MBE). Four APT data sets have been obtained, with fields of view up to 400 nm in depth and 120 nm in diameter. These data sets contain material from the InGaN quantum well (QW) active region, as well as the surrounding p- and n-doped waveguide and cladding layers, enabling comprehensive study of the structure and composition of the LD structure. Two regions of the same sample, with different average indium contents (18% and 16%) in the QW region, were studied. The APT data are shown to provide easy access to the p-type dopant levels, and the composition of a thin AlGaN barrier layer. Next, the distribution of indium within the InGaN QW was analyzed, to assess any possible inhomogeneity of the distribution of indium (''indium clustering''). No evidence for a statistically significant deviation from a random distribution was found, indicating that these MBE-grown InGaN QWs do not require indium clusters for carrier localization. However, the APT data show steps in the QW interfaces, leading to well-width fluctuations, which may act to localize carriers. Additionally, the unexpected presence of a small amount (x = 0.005) of indium in a layer grown intentionally as GaN was revealed. Finally, the same statistical method applied to the QW was used to show that the indium distribution within a thick InGaN waveguide layer in the n-doped region did not show any deviation from randomness.

Bennett, Samantha E.; Humphreys, Colin J.; Oliver, Rachel A. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Smeeton, Tim M.; Hooper, Stewart E.; Heffernan, Jonathan [Sharp Laboratories of Europe Limited, Edmund Halley Road, Oxford Science Park, Oxford, OX4 4GB (United Kingdom); Saxey, David W.; Smith, George D. W. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom)

2012-03-01T23:59:59.000Z

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.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Lattice dynamics of GaN: Effects of 3d electrons  

Science Journals Connector (OSTI)

We perform first-principles calculations of structural, dielectric, and lattice-dynamical properties of cubic GaN. The equilibrium structure is obtained using the plane-wave pseudopotential approach within the density-functional theory and local-density approximation. The dielectric and vibrational properties are computed within the density-functional perturbation theory. The effect of the Ga 3d electrons is treated by taking into account the nonlinear core corrections for the exchange and correlation energy. The importance of 3d electrons for the bonding strength is determined, and their influence on the dielectric and dynamical properties of GaN is analyzed and discussed.

K. Karch; F. Bechstedt; T. Pletl

1997-08-15T23:59:59.000Z

162

K.K. Gan ATLAS Tracker Upgrade Workshop 1 Nov 5, 2008  

E-Print Network [OSTI]

channel Preliminary #12;K.K. Gan ATLAS Tracker Upgrade Workshop 8 Radiation-Hardness of GaAs PIN AOC.03 AOC 5.0 0.60 0.04 Optowell 3.125 0.60 0.10 Hamamatsu G8921 2.5 0.50 0.20 Si Taiwan 1.0 0.55 0 irradiation with SLHC dose: AOC(5 & 10 G) have good power #12;K.K. Gan ATLAS Tracker Upgrade Workshop 12

Gan, K. K.

163

Ge doped GaN with controllable high carrier concentration for plasmonic applications  

SciTech Connect (OSTI)

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

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

2013-12-09T23:59:59.000Z

164

Growth of CdTe Films on Amorphous Substrates Using CaF2 Nanorods as a Buffer Layer  

E-Print Network [OSTI]

Growth of CdTe Films on Amorphous Substrates Using CaF2 Nanorods as a Buffer Layer NICHOLAS LICAUSI biaxially textured CdTe films were grown on biaxial CaF2 buffer layers. The CaF2 nanorods were grown by oblique angle vapor deposition and possessed a {111}h121i biaxial texture. The CdTe film was deposited

Wang, Gwo-Ching

165

Oxidation of In2S3 films to synthetize In2S3(1-x)O3x thin films as a buffer layer in solar cells  

E-Print Network [OSTI]

Oxidation of In2S3 films to synthetize In2S3(1-x)O3x thin films as a buffer layer in solar cells S layers for solar cells. PACS : 68.55.ag Semiconductors, 68.55.J Morphology of films , 68.55.Nq the oxidation occurs is strongly dependent on the texture of deposited films. As-grown films deposited

Boyer, Edmond

166

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

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

167

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

168

Journal of Crystal Growth 241 (2002) 4550 Boron doping of silicon layers grown by liquid phase epitaxy  

E-Print Network [OSTI]

advantage. One disadvantage of tin is that layers grown using a tin melt may *Corresponding author. Tel Energy Systems, Department of Engineering, Australian National University, Acton, 0200, Australia film solar cell applications as it allows the growth of a back surface field and a lightly doped bulk

169

Crystalline phases of II-VI compound semiconductors grown by pulsed laser deposition  

E-Print Network [OSTI]

-VI compound semiconductors, ZnS, ZnSe, CdS, CdSe, and CdTe, were grown epitaxially on 111 and 100 InP and Ga and mirror-like surface morphology. It was found that, on 111 -oriented substrates, CdS and CdSe films were, which is the main source of the troublesome native doping in II-VI compounds. High energy atoms and ions

Kwok, Hoi S.

170

TEM studies of Ge nanocrystal formation in PECVD grown  

Science Journals Connector (OSTI)

We investigate the effect of annealing on the Ge nanocrystal formation in multilayered germanosilicate–oxide films grown on Si substrates by plasma enhanced chemical vapour deposition (PECVD). The multilayered samples were annealed at temperatures ranging from 750 to 900?°C for 5 min under nitrogen atmosphere. The onset of formation of Ge nanocrystals, at 750?°C, can be observed via high resolution TEM micrographs. The diameters of Ge nanocrystals were observed to be between 5 and 14 nm. As the annealing temperature is raised to 850?°C, a second layer of Ge nanocrystals forms next to the original precipitation band, positioning itself closer to the substrate SiO2 interface. High resolution cross section TEM images, electron diffraction and electron energy-loss spectroscopy as well as energy-dispersive x-ray analysis (EDAX) data all indicate that Ge nanocrystals are present in each layer.

S A?an; A Dana; A Aydinli

2006-01-01T23:59:59.000Z

171

K.K. Gan Group B Meeting 1 VCSEL/PIN irradiation in pre-qualification  

E-Print Network [OSTI]

/vendor VCSEL: AOC 10 Gb/s, AOC 5 Gb/s, Optowell (2.5 Gb/s) GaAs PIN: try to order 12-channel Hamamatsu bare "need custom alignment Control Sample of PIN #12;K.K. Gan Group B Meeting 4 AOC 10 Gb/s? 12

Gan, K. K.

172

K.K. Gan RD07 1 Radiation-Hard Optical Link for SLHC  

E-Print Network [OSTI]

arrays have very good optical power Optowell AOC ULM 10GULM 5G Pre-irrad #12;K.K. Gan RD07 12 Optowell 71 to SLHC dosage more VCSELs might survive with more annealing during irradiation SLHC AOC 71 MRad 0.0 0

Gan, K. K.

173

Optimal Decentralized Protocol for Electric Vehicle Charging Lingwen Gan Ufuk Topcu Steven Low  

E-Print Network [OSTI]

Abstract-- Motivated by the power-grid-side challenges in the integration of electric vehicles, we proposeOptimal Decentralized Protocol for Electric Vehicle Charging Lingwen Gan Ufuk Topcu Steven Low a decentralized protocol for negotiating day-ahead charging schedules for electric vehicles. The overall goal

Low, Steven H.

174

Reverse-bias leakage current reduction in GaN Schottky diodes by electrochemical surface treatment  

E-Print Network [OSTI]

Reverse-bias leakage current reduction in GaN Schottky diodes by electrochemical surface treatment Received 15 July 2002; accepted 27 December 2002 An electrochemical surface treatment has been developed to the large power consumption and noise levels that can be present in circuits that incorporate such devices.1

Yu, Edward T.

175

VISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN  

E-Print Network [OSTI]

. At the same time novel work is being conducted using rare earth elements as sources of light emission. Results. III-V semiconductors doped with rare-earth elements have also been used10VISIBLE AND INFRARED RARE-EARTH ACTIVATED ELECTROLUMINESCENCE FROM ERBIUM DOPED GaN M. Garter*, R

Steckl, Andrew J.

176

An Effective Subdivision Algorithm for Diffuse Scattering of Ray Tracing Mingming Gan1  

E-Print Network [OSTI]

Department of Electrical and Information Technology, Lund University, Lund, Sweden Contact: gan@ftw.at Abstract Accurate modeling of electromagnetic wave propagation by means of ray tracing (RT) includes by evaluating the power delay profile (PDP), delay spread and angular spread. 1 Introduction Diffuse scattering

Zemen, Thomas

177

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

E-Print Network [OSTI]

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

Schlick, Tamar

178

Metalorganic Chemical Vapor Deposition Route to GaN Nanowires with Triangular  

E-Print Network [OSTI]

Metalorganic Chemical Vapor Deposition Route to GaN Nanowires with Triangular Cross Sections Tevye widths of 15-200 nm. Transmission electron microscopy confirmed that the wires were single as a carrier gas, was percolated through the TMG precursor and coupled with a second nitrogen line to give

Yang, Peidong

179

Growth of Hydrogenated Amorphous Silicon Films by ArF Excimer Laser Photodissociation of Disilane  

Science Journals Connector (OSTI)

Hydrogenated amorphous silicon films have been grown on glass substrates by photodissociation of disilane using a pulsed ArF excimer laser foe the first time. Electrical and optical properties of the films have been examined. It was found that the magnitude of the gap energy of laser CVD films is rather large as compared to that of films obtained by a conventional plasma CVD. Preliminary examinations to control the conductivity by impurity doping have also been performed.

Akihiko Yoshikawa; Shigeki Yamaga

1984-01-01T23:59:59.000Z

180

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

SciTech Connect (OSTI)

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

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

2014-05-28T23:59:59.000Z

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
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181

Structure, magnetic properties and magnetoelastic anisotropy in epitaxial Sr(Ti???Co?)O? films  

E-Print Network [OSTI]

We report the structure, magnetic properties and magnetoelastic anisotropy of epitaxial Sr(Ti???Co?)O? films grown on LaAlO? (001) and SrTiO? (001) substrates by pulsed laser deposition. Room temperature ferromagnetism was ...

Bi, Lei

182

Structural and Magnetic Properties of Epitaxial MnSi(111) Thin Films.  

E-Print Network [OSTI]

??MnSi(111) films were grown on Si(111) substrates by solid phase epitaxy (SPE) and molecular beam epitaxy (MBE) to determine their magnetic structures. A lattice mismatch… (more)

Karhu, Eric

2012-01-01T23:59:59.000Z

183

Microstructure and magnetoelectric properties in Pb,,ZrxTi1-x...O3Ni composite ferroic films  

E-Print Network [OSTI]

Microstructure and magnetoelectric properties in Pb,,ZrxTi1-x...O3­Ni composite ferroic films 15213 Presented on 31 October 2005; published online 19 April 2006 Ferroic composite thin films composite films grown on SiO2/Si substrates at 650 °C, a perovskite structure was obtained when the Ni

Laughlin, David E.

184

K.K. Gan Joint SLHC Opto Working Group 1 Results of Opto-Link R&D  

E-Print Network [OSTI]

Joint SLHC Opto Working Group 11 K.K. Gan 11 VCSEL Power vs Dosage AOC (5 & 10 Gb/s) survive to SLHC instead of 5,000 fb-1 PIN: Si: TrueLight, Hamamatsu GaAs: AOC, ULM, Optowell VCSEL: AOC, Optowell, ULM? August 08 with 24 GeV/c p (CERN) #12;K.K. Gan Joint SLHC Opto Working Group

Gan, K. K.

185

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

SciTech Connect (OSTI)

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

186

Interface magnetism of iron grown on sulfur and hydrogen passivated GaAs(001)  

SciTech Connect (OSTI)

Sulfur (S) and hydrogen (H) atom passivated GaAs(001) templates were used for deposition of ultrathin crystalline Fe films using molecular beam epitaxy, where the Fe thickness ranged from 10 to 45 atomic layers. Reflection high-energy electron diffraction patterns showed that the S- and H-passivated surfaces had no and very weak (1 x 2) superlattice reconstructions, respectively. This indicates that these GaAs(001) templates have a square-like symmetry. Magnetic anisotropies were investigated using the in-plane angular dependence of ferromagnetic resonance at 36 GHz. The in-plane cubic and uniaxial anisotropies and perpendicular uniaxial field were described by bulk and interface contributions, indicating that the Fe films have a high lattice coherence. The magnetic properties of the Fe films were compared to those grown on more commonly used GaAs(001) templates having a (4 x 6) reconstruction with an As-rich in-plane uniaxial symmetry. The Fe films grown on S-passivated templates exhibited unique magnetic properties caused by a decreased lattice spacing compared to the bulk Fe.

Kardasz, B.; Watkins, S. P.; Montoya, E. A.; Burrowes, C.; Girt, E.; Heinrich, B.

2012-04-01T23:59:59.000Z

187

Impact of structural imperfections on the energy-level alignment in organic films  

Science Journals Connector (OSTI)

This paper reports that structural imperfection in an organic thin film modulates the electronic structure to result in a serious band bending and change in the energy-level alignment (ELA) at the organic-conductor interface. Ultraviolet photoelectron spectroscopy (UPS) and metastable atom electron spectroscopy (MAES) were adopted to investigate thickness dependences of the electronic structure of polar phthalocyanine (chlorogallium phthalocyanine) thin films grown on graphite with respect to the film structure. We observed a large band-bending–like shift of occupied molecular-orbital bands toward the Fermi level and a continuous increase in the vacuum level for the as-grown film, whereas these phenomena were considerably suppressed by annealing the film. Both the as-grown and annealed films were characterized as essentially the same stacked bilayer film structure; however, high-resolution UPS and MAES measurements evidenced that there are structural defects in the as-grown film but not clearly in the annealed film, indicating that the defects are the origin of the modulation of the ELA and the band bending. Controlling the structural imperfections is a key issue for the desired ELA in organic devices.

T. Hosokai; H. Machida; A. Gerlach; S. Kera; F. Schreiber; N. Ueno

2011-05-09T23:59:59.000Z

188

Anodic films  

SciTech Connect (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

189

Near-field microwave microscopy of high-? oxides grown on graphene with an organic seeding layer  

SciTech Connect (OSTI)

Near-field scanning microwave microscopy (SMM) is used for non-destructive nanoscale characterization of Al{sub 2}O{sub 3} and HfO{sub 2} films grown on epitaxial graphene on SiC by atomic layer deposition using a self-assembled perylene-3,4,9,10-tetracarboxylic dianhydride seeding layer. SMM allows imaging of buried inhomogeneities in the dielectric layer with a spatial resolution close to 100?nm. The results indicate that, while topographic features on the substrate surface cannot be eliminated as possible sites of defect nucleation, the use of a vertically heterogeneous Al{sub 2}O{sub 3}/HfO{sub 2} stack suppresses formation of large outgrowth defects in the oxide film, ultimately improving lateral uniformity of the dielectric film.

Tselev, Alexander, E-mail: tseleva@ornl.gov; Kalinin, Sergei V. [Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, Tennessee 37831 (United States)] [Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, Tennessee 37831 (United States); Sangwan, Vinod K.; Jariwala, Deep; Lauhon, Lincoln J. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)] [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Marks, Tobin J.; Hersam, Mark C. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States) [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States)

2013-12-09T23:59:59.000Z

190

Design and Simulation of Novel Enhancement Mode 5–20 kV GaN Vertical Superjunction High Electron Mobility Transistors for Smart Grid Applications  

Science Journals Connector (OSTI)

We report on the design, simulations and optimization of a novel enhancement mode 5–20 kV GaN vertical superjunction (SJ) high electron mobility transistor (HEMT). We optimize the space charge in GaN pillars using GaN SJ p–n diode for the best trade-off between breakdown voltage (BV) and specific on-resistance (Ronsp), by varying the pillar dosage, length and width. The resulting GaN SJ field effect transistor (FET) structure is projected to have, for example, Ronsp of 4.2 m? cm2 with BV of 12.4 kV.

Zhongda Li; T. Paul Chow

2013-01-01T23:59:59.000Z

191

Tunneling spectroscopy of superconducting MoN and NbTiN grown by atomic layer deposition  

SciTech Connect (OSTI)

A tunneling spectroscopy study is presented of superconducting MoN and Nb{sub 0.8}Ti{sub 0.2}N thin films grown by atomic layer deposition (ALD). The films exhibited a superconducting gap of 2?meV and 2.4?meV, respectively, with a corresponding critical temperature of 11.5?K and 13.4?K, among the highest reported T{sub c} values achieved by the ALD technique. Tunnel junctions were obtained using a mechanical contact method with a Au tip. While the native oxides of these films provided poor tunnel barriers, high quality tunnel junctions with low zero bias conductance (below ?10%) were obtained using an artificial tunnel barrier of Al{sub 2}O{sub 3} on the film's surface grown ex situ by ALD. We find a large critical current density on the order of 4?×?10{sup 6}?A/cm{sup 2} at T?=?0.8T{sub c} for a 60?nm MoN film and demonstrate conformal coating capabilities of ALD onto high aspect ratio geometries. These results suggest that the ALD technique offers significant promise for thin film superconducting device applications.

Groll, Nickolas R., E-mail: ngroll@anl.gov; Klug, Jeffrey A.; Claus, Helmut; Pellin, Michael J.; Proslier, Thomas, E-mail: proslier@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Cao, Chaoyue; Becker, Nicholas G.; Zasadzinski, John F. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Altin, Serdar [Fen Edebiyat Fakultesi, Fizik Bolumu, Inonu Universitesi, 44280 Malatya (Turkey)

2014-03-03T23:59:59.000Z

192

Identification of the gallium vacancy-oxygen pair defect in GaN  

SciTech Connect (OSTI)

Cation vacancies like V{sub Ga}, V{sub Al} and their complexes with oxygen are predicted to be abundant in III-nitrides and to play an important role in nonradiative recombination. Appearing in triple or double negatively charged states, they are not paramagnetic and have not so far been detected by magnetic resonance even under illumination. In this Brief Report, we demonstrate an efficient way to make cation vacancy defects in GaN detectable by electron paramagnetic resonance and present our identification of the V{sub Ga}O{sub N} pair in GaN which is the model material for the III-nitrides and their alloys.

Son, N. T.; Hemmingsson, C. G.; Janzen, E. [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Paskova, T.; Evans, K. R. [Kyma Technologies Inc., 8829 Midway West Road, Raleigh, North Carolina 27617 (United States); Usui, A. [R and D Division, Furukawa Co., Ltd., Tsukuba, Ibaraki 305-0856 (Japan); Morishita, N.; Ohshima, T. [Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Isoya, J. [Graduate School of Library, Information and Media Studies, University of Tsukuba, Tsukuba, Ibaraki 305-8550 (Japan); Monemar, B. [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Nanometer Structure Consortium, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)

2009-10-15T23:59:59.000Z

193

Subpicosecond time-resolved Raman studies of nonequilibrium excitations in wurtzite GaN  

SciTech Connect (OSTI)

Non-equilibrium electron distributions as well as phonon dynamics in wurtzite GaN have been measured by subpicosecond time-resolved Raman spectroscopy. The experimental results have demonstrated that for electron densities n {ge} 5 {times} 10{sup 17} cm{sup {minus}3}, the non-equilibrium electron distributions in wurtzite GaN can be very well described by Fermi-Dirac distribution functions with the temperature of electrons substantially higher than that of the lattice. The population relaxation time of longitudinal optical phonons was directly measured to be {tau} {approx_equal} 5 {+-} 1 ps at T = 25 K. The experimental results on the temperature dependence of the lifetime of longitudinal optical phonons suggest that the primary decay channels for these phonons are the decay into (1) one transverse optical phonon and one high energy, longitudinal or transverse acoustical phonons; and (2) one transverse optical phonon and one E{sub 2} phonon.

Tsen, K.T.; Ferry, D.K. [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics and Astronomy; Joshi, R.P. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Electrical Engineering; Botchkarev, A.; Sverdlov, B.; Salvador, A.; Morkoc, H. [Univ. of Illinois, Urbana, IL (United States). Coordinated Science Lab.

1997-12-31T23:59:59.000Z

194

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

SciTech Connect (OSTI)

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

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

2014-02-21T23:59:59.000Z

195

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

E-Print Network [OSTI]

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

Gan, K. K.

196

Theoretical and experimental study of dynamics of photoexcited carriers in GaN  

SciTech Connect (OSTI)

We present a theoretical and experimental study of the sub-picosecond dynamics of photo-excited carriers in GaN. In the theoretical model, interaction with an external ultrafast laser pulse is treated coherently and to account for the scattering mechanisms and dephasing processes, a generalized Monte-Carlo simulation is used. The scattering mechanisms included are carrier interactions with polar optical phonons and acoustic phonons, and carrier-carrier Coulomb interactions. We study the effect of different scattering mechanisms on the carrier densities. In the case that the excitation energy satisfies the threshold for polar optical scattering, phonon contribution is the dominant process in relaxing the system, otherwise, carrier-carrier mechanism is dominant. Furthermore, we present the temperature and pulse power dependent normalized luminescence intensity. The results are presented over a range of temperatures, electric field, and excitation energy of the laser pulse. For comparison, we also report the experimental time-resolved photoluminescence studies on GaN samples. There is a good agreement between the simulation and experiment in normalized luminescence intensity results. Therefore, we show that we can explain the dynamics of the photo-excited carriers in GaN by including only carrier-carrier and carrier-phonon interactions and a relatively simple two-band electronic structure model.

Shishehchi, Sara; Bellotti, Enrico, E-mail: bellotti@bu.edu [ECE Department, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215 (United States); Rudin, Sergey; Garrett, Gregory A.; Wraback, Michael [Sensors and Electron Devices Directorate, US Army Research Laboratory, 2800 Powder Mill Rd, Adelphi, Maryland 20783 (United States)

2013-12-21T23:59:59.000Z

197

Red light emitting solid state hybrid quantum dot–near-UV GaN LED devices  

Science Journals Connector (OSTI)

We produced core–shell (CdSe)ZnSe quantum dots by direct colloidal chemical synthesis and the surface-passivation method—an overcoating of the core CdSe with a larger-bandgap material ZnSe. The (CdSe)ZnSe quantum dots(QDs) play the role of a colour conversion centre. We call these quantum dots nanophosphors. We fabricated red light emitting hybrid devices of (CdSe)ZnSe QDs and a near-UV GaN LED by combining red light emitting (CdSe)ZnSe quantum dots (as a colour conversion centre) with a near-UV(NUV) GaN LED chip (as an excitation source). A few good red phosphors have been known for UV excitation wavelengths, and red phosphors for UV excitation have been sought for a long time. Here we tested the possibility of using (CdSe)ZnSe QDs as red nanophosphors for UV excitation. The fabricated red light emitting hybrid device of (CdSe)ZnSe and a NUV GaN LED chip showed a good luminance. We demonstrated that the (CdSe)ZnSe quantum dots were promising red nanophosphors for NUV excitation and that a red LED made of QDs and a NUV excitation source was a highly efficient hybrid device.

Hongjoo Song; Seonghoon Lee

2007-01-01T23:59:59.000Z

198

Room temperature in-plane ?100? magnetic easy axis for Fe{sub 3}O{sub 4}/SrTiO{sub 3}(001):Nb grown by infrared pulsed laser deposition  

SciTech Connect (OSTI)

We examine the magnetic easy-axis directions of stoichiometric magnetite films grown on SrTiO{sub 3}:Nb by infrared pulsed-laser deposition. Spin-polarized low-energy electron microscopy reveals that the individual magnetic domains are magnetized along the in-plane ?100? film directions. Magneto-optical Kerr effect measurements show that the maxima of the remanence and coercivity are also along in-plane ?100? film directions. This easy-axis orientation differs from bulk magnetite and films prepared by other techniques, establishing that the magnetic anisotropy can be tuned by film growth.

Monti, Matteo; Sanz, Mikel; Oujja, Mohamed; Rebollar, Esther; Castillejo, Marta; Marco, José F.; Figuera, Juan de la, E-mail: juan.delafiguera@iqfr.csic.es [Instituto de Química Física “Rocasolano,” CSIC, Madrid E-28006 (Spain); Pedrosa, Francisco J.; Bollero, Alberto [IMDEA Nanociencia, Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid E-28049 (Spain); Camarero, Julio; Cuñado, Jose Luis F. [IMDEA Nanociencia, Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid E-28049 (Spain); Dpto. de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049 (Spain); Nemes, Norbert M. [Dpto. de Física Aplicada III, Universidad Complutense de Madrid, Madrid E-28040 (Spain); Mompean, Federico J.; Garcia-Hernández, Mar [Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid E-28049 (Spain); Nie, Shu; McCarty, Kevin F. [Sandia National Laboratories, Livermore, California 94550 (United States); N'Diaye, Alpha T.; Chen, Gong; Schmid, Andreas K. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2013-12-14T23:59:59.000Z

199

The growth characteristics of microcrystalline Si thin film deposited by atmospheric pressure plasma-enhanced chemical vapor deposition  

Science Journals Connector (OSTI)

Microcrystalline silicon thin film was grown by atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) ... with a cylindrical rotary electrode supplied with 150 MHz very-high-frequency power. T...

Jung-Dae Kwon

2013-11-01T23:59:59.000Z

200

Characterization of chemical bath deposited CdS thin films doped with methylene blue and Er3+  

Science Journals Connector (OSTI)

The optical, electrical, and structural properties of CdS thin films grown by chemical bath deposition and simultaneously doped with methylene blue (MB) and Er3+ were studied. Doping was achieved by adding a c...

S. A. Tomás; R. Lozada-Morales; O. Portillo…

2008-01-01T23:59:59.000Z

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.


201

Microstructure and electrical properties of p-type phosphorus-doped ZnO films  

Science Journals Connector (OSTI)

The microscopic defects and their effects on the electrical properties of phosphorus-doped ZnO films epitaxially grown on (0?0?0?1) sapphire and ZnO substrates by pulsed laser deposition are studied. While threading dislocations were observed only in heteroepitaxial films, a high density of partial dislocations associated with interstitial dislocation loops was observed in films grown on both substrates. These dislocations provide sinks to quench native donors and favour the injection of zinc vacancies to form acceptor-complex defects, thus leading to p-type conductivity.

A Allenic; W Guo; Y B Chen; Y Che; Z D Hu; B Liu; X Q Pan

2008-01-01T23:59:59.000Z

202

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

203

Tailoring the index of refraction of nanocrystalline hafnium oxide thin films  

SciTech Connect (OSTI)

Hafnium oxide (HfO{sub 2}) films were grown by sputter-deposition by varying the growth temperature (T{sub s}?=?25–700?°C). HfO{sub 2} films grown at T{sub s}?grown at T{sub s}???200?°C were monoclinic, nanocrystalline with (1{sup ¯}11) texturing. X-ray reflectivity (XRR) analyses indicate that the film-density (?) increases with increasing T{sub s}. The index of refraction (n) profiles derived from spectroscopic ellipsometry analyses follow the Cauchy dispersion relation. Lorentz-Lorenz analysis (n{sub (?)}?=?550?nm) and optical-model adopted agree well with the XRR data/analyses. A direct T{sub s}-?-n relationship suggests that tailoring the optical quality is possible by tuning T{sub s} and the microstructure of HfO{sub 2} films.

Vargas, Mirella [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)] [Department of Metallurgical and Materials Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States); Murphy, N. R. [Materials and Manufacturing Directorate (RX), 3005 Hobson Way, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio 45433 (United States)] [Materials and Manufacturing Directorate (RX), 3005 Hobson Way, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio 45433 (United States); Ramana, C. V., E-mail: rvchintalapalle@utep.edu [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)

2014-03-10T23:59:59.000Z

204

Subeutectic Growth of Single-Crystal Silicon Nanowires Grown on and Wrapped with Graphene Nanosheets: High-Performance Anode Material for Lithium-Ion Battery  

Science Journals Connector (OSTI)

Subeutectic Growth of Single-Crystal Silicon Nanowires Grown on and Wrapped with Graphene Nanosheets: High-Performance Anode Material for Lithium-Ion Battery ... Yu, A.; Park, H. W.; Davies, A.; Higgins, D.; Chen, Z.; Xaio, X.Free-Standing Layer-by-Layer Hybrid Thin Film of Graphene-MnO2 Nanotube as Anode for Lithium Ion Batteries J. Phys. ...

Fathy M Hassan; Abdel Rahman Elsayed; Victor Chabot; Rasim Batmaz; Xingcheng Xiao; Zhongwei Chen

2014-07-31T23:59:59.000Z

205

Scanning tunneling microscopy on unpinned GaN(11¯00) surfaces: Invisibility of valence-band states  

Science Journals Connector (OSTI)

We investigated the origins of the tunnel current in scanning tunneling microscopy (STM) and spectroscopy experiments on GaN(11¯00) surfaces. By calculating the tunnel currents in the presence of a tip-induced band bending for unpinned n-type GaN(11¯00) surfaces, we demonstrate that only conduction-band states are observed at positive and negative voltage polarities independent of the doping concentration. Valence-band states remain undetectable because tunneling out of the electron-accumulation zone in conduction-band states dominates by four orders of magnitude. As a result band-gap sizes cannot be determined by STM on unpinned GaN(11¯00) surfaces. Appropriate band-edge positions and gap sizes can be determined on pinned surfaces.

Ph. Ebert, L. Ivanova, and H. Eisele

2009-08-24T23:59:59.000Z

206

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

SciTech Connect (OSTI)

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

207

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

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

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

208

Oxygen off-stoichiometry and phase separation in EuO thin films  

SciTech Connect (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

209

Control of magnetization reversal in oriented strontium ferrite thin films  

SciTech Connect (OSTI)

Oriented Strontium Ferrite films with the c axis orientation were deposited with varying oxygen partial pressure on Al{sub 2}O{sub 3}(0001) substrate using Pulsed Laser Deposition technique. The angle dependent magnetic hysteresis, remanent coercivity, and temperature dependent coercivity had been employed to understand the magnetization reversal of these films. It was found that the Strontium Ferrite thin film grown at lower (higher) oxygen partial pressure shows Stoner-Wohlfarth type (Kondorsky like) reversal. The relative importance of pinning and nucleation processes during magnetization reversal is used to explain the type of the magnetization reversal with different oxygen partial pressure during growth.

Roy, Debangsu, E-mail: debangsu@physics.iisc.ernet.in; Anil Kumar, P. S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

2014-02-21T23:59:59.000Z

210

Perpendicular ferrimagnetism in strained Mn{sub 2}As film  

SciTech Connect (OSTI)

Ferrimagnetic Mn{sub 2}As thin films with perpendicular magnetic anisotropy were successfully grown on Si(100) by molecular-beam epitaxy. From the reflection high-energy electron diffraction and X-ray diffraction patterns, the orientation of the Mn{sub 2}As film on Si was along the c-axis in the tetragonal crystal structure. Mn{sub 2}As film exhibited ferrimagnetic ordering at temperatures greater than 300 K, which differs from antiferromagnetic or paramagnetic behaviors in the bulk form. The magnetic moment of Mn{sub 2}As determined by saturated magnetization was 0.51 {mu}{sub B} per unit cell.

Hwang, Younghun; Choi, Jeongyong; Duc Dung, Dang; Shin, Yooleemi; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

2011-03-15T23:59:59.000Z

211

Vibrational spectra of CO adsorbed on oxide thin films: A tool to probe the surface defects and phase changes of oxide thin films  

SciTech Connect (OSTI)

Thin films of iron oxide were grown on Pt(111) single crystals using cycles of physical vapor deposition of iron followed by oxidative annealing in an ultrahigh vacuum apparatus. Two procedures were utilized for film growth of ?15–30 ML thick films, where both procedures involved sequential deposition+oxidation cycles. In procedure 1, the iron oxide film was fully grown via sequential deposition+oxidation cycles, and then the fully grown film was exposed to a CO flux equivalent to 8 × 10{sup ?7} millibars, and a vibrational spectrum of adsorbed CO was obtained using infrared reflection-absorption spectroscopy. The vibrational spectra of adsorbed CO from multiple preparations using procedure 1 show changes in the film termination structure and/or chemical nature of the surface defects—some of which are correlated with another phase that forms (“phase B”), even before enough of phase B has formed to be easily detected using low energy electron diffraction (LEED). During procedure 2, CO vibrational spectra were obtained between deposition+oxidation cycles, and these spectra show that the film termination structure and/or chemical nature of the surface defects changed as a function of sequential deposition+oxidation cycles. The authors conclude that measurement of vibrational spectra of adsorbed CO on oxide thin films provides a sensitive tool to probe chemical changes of defects on the surface and can thus complement LEED techniques by probing changes not visible by LEED. Increased use of vibrational spectra of adsorbed CO on thin films would enable better comparisons between films grown with different procedures and by different groups.

Savara, Aditya, E-mail: savaraa@ornl.gov [Chemical Sciences Division, Oak Ridge National Lab, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831 (United States)

2014-03-15T23:59:59.000Z

212

Functional blueprints: an approach to modularity in grown systems  

Science Journals Connector (OSTI)

The engineering of grown systems poses fundamentally different system integration challenges than ordinary engineering of static designs. On the one hand, a grown system must be capable of surviving not only in its final form, but at every intermediate ...

Jacob Beal

2010-09-01T23:59:59.000Z

213

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

SciTech Connect (OSTI)

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

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

1997-08-01T23:59:59.000Z

214

The impact of nanoperforation on persistent photoconductivity and optical quenching effects in suspended GaN nanomembranes  

SciTech Connect (OSTI)

We report on fabrication of suspended ?15?nm thick GaN membranes nanoperforated in an ordered fashion using direct writing of negative charges by focused ion beam and subsequent photoelectrochemical etching of GaN epilayers. Both continuous and nanoperforated membranes exhibit persistent photoconductivity (PPC), which can be optically quenched under excitation by 546?nm radiation. Optical quenching of PPC occurs also under relatively intense intrinsic excitation of nanoperforated membranes by 355?nm radiation at T?

Volciuc, Olesea, E-mail: olesea.volciuc@gmail.com [Institute of Solid State Physics, University of Bremen, Bremen 28334 (Germany) [Institute of Solid State Physics, University of Bremen, Bremen 28334 (Germany); National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova, Republic of); Braniste, Tudor [National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova, Republic of)] [National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova, Republic of); Tiginyanu, Ion, E-mail: tiginyanu@asm.md [National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova, Republic of) [National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova, Republic of); Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of); Stevens-Kalceff, Marion A. [School of Physics, University of New South Wales, Sydney NSW 2052 (Australia)] [School of Physics, University of New South Wales, Sydney NSW 2052 (Australia); Ebeling, Jakob; Aschenbrenner, Timo; Hommel, Detlef; Gutowski, Jürgen [Institute of Solid State Physics, University of Bremen, Bremen 28334 (Germany)] [Institute of Solid State Physics, University of Bremen, Bremen 28334 (Germany); Ursaki, Veaceslav [Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of)] [Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of)

2013-12-09T23:59:59.000Z

215

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

SciTech Connect (OSTI)

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

216

Surface diffusion coefficient of Au atoms on single layer graphene grown on Cu  

SciTech Connect (OSTI)

A 5?nm thick Au film was deposited on single layer graphene sheets grown on Cu. By thermal processes, the dewetting phenomenon of the Au film on the graphene was induced so to form Au nanoparticles. The mean radius, surface-to-surface distance, and surface density evolution of the nanoparticles on the graphene sheets as a function of the annealing temperature were quantified by scanning electron microscopy analyses. These quantitative data were analyzed within the classical mean-field nucleation theory so to obtain the temperature-dependent Au atoms surface diffusion coefficient on graphene: D{sub S}(T)=[(8.2±0.6)×10{sup ?8}]exp[?(0.31±0.02(eV)/(at) )/kT]?cm{sup 2}/s.

Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Cacciato, G.; Grimaldi, M. G. [Dipartimento di Fisica ed Astronomia-Universitá di Catania, via S. Sofia 64, 95123 Catania, Italy and MATIS IMM-CNR, via S. Sofia 64, 95123 Catania (Italy)

2014-02-28T23:59:59.000Z

217

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

SciTech Connect (OSTI)

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

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

2012-05-15T23:59:59.000Z

218

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

E-Print Network [OSTI]

B 22, 1145 ?2004?. A. Armstrong, A. R. Arehart, D. Green, U.San Diego, 1992?. A. Armstrong, A. R. Arehart, and S. A.molecular beam epitaxy A. Armstrong Department of Electrical

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

2006-01-01T23:59:59.000Z

219

Doping of MBE grown cubic GaN on 3C-SiC (001) by CBr4 ,E. Tschumak1  

E-Print Network [OSTI]

source. The CBr4 beam equivalent pressure was established by a needle valve and was varied between 2x10 has a very low diffusion coefficient [3]. It is also known from p-doping in (Al)GaAs that carbon4 beam equivalent pressure (BEP) was established by a needle valve and was varied between 2x10

As, Donat Josef

220

K.K. Gan TWEPP08 1 Results on Opto-Link R&D  

E-Print Network [OSTI]

-Hardness of GaAs PIN AOC ULM irradiate PIN with 24 GeV protons at CERN SLHC dosage: 2.6 x 1015 p/cm2 (8.2 x.25 0.50 0.13 AOC 2.5 0.60 0.19 Optowell 3.125 0.60 0.25 Hamamatsu G8921 2.5 0.50 0.32 Si Taiwan 1.0 0 channels 2008 irradiation with SLHC dosage: AOC(5 & 10 G) have good power #12;K.K. Gan TWEPP08 8

Gan, K. K.

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

K.K. Gan Siena08 1 Results on Opto-Link R&D  

E-Print Network [OSTI]

-Hardness of GaAs PIN AOC ULM irradiate PIN with 24 GeV protons at CERN SLHC dosage: 2.6 x 1015 p/cm2 (8.2 x.25 0.50 0.13 AOC 2.5 0.60 0.19 Optowell 3.125 0.60 0.25 Hamamatsu G8921 2.5 0.50 0.32 Si Taiwan 1.0 0 channels 2008 irradiation with SLHC dosage: AOC(5 & 10 G) have good power #12;K.K. Gan Siena08 9

Gan, K. K.

222

Self-Assembled Monolayers of Alkylphosphonic Acid on GaN Substrates  

Science Journals Connector (OSTI)

In addition to their applications for short-wavelength optoelectronic and high-power electronics, group III nitrides (AlN, GaN, and InN) have been employed as components of chemical and biological sensors for gas and solution samples. ... (27) In the basic solution, ?water decreased quickly to reach a smaller plateau value, probably reflecting the electrostatic repulsion between the deprotonated ODPA and negatively charged gallium oxide surface(46) in addition to the higher solubility of deprotonated ODPA in more basic solution. ... Gallium nitride is a wide band gap semiconductor that demonstrates a unique set of optical and electrical properties as well as aqueous stability and biocompatibility. ...

Takashi Ito; Sarah M. Forman; Chundi Cao; Feng Li; Charles R. Eddy, Jr.; Michael A. Mastro; Ronald T. Holm; Richard L. Henry; Keith L. Hohn; J. H. Edgar

2008-06-04T23:59:59.000Z

223

Spectroscopic Analysis of Impurity Precipitates in CdS Films  

SciTech Connect (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

224

STRUCTURAL AND CHEMICAL STUDIES ON CdTe/CdS THIN FILM SOLAR CELLS WITH ANALYTICAL TRANSMISSION ELECTRON MICROSCOPY  

E-Print Network [OSTI]

STRUCTURAL AND CHEMICAL STUDIES ON CdTe/CdS THIN FILM SOLAR CELLS WITH ANALYTICAL TRANSMISSION, A. N. Tiwari Thin Film Physics Group, Laboratory for Solid State Physics, Technopark ETH-Building, Technoparkstr. 1, CH-8005 Zurich, Switzerland ABSTRACT: CdTe/CdS thin £lm solar cells have been grown by closed

Romeo, Alessandro

225

Growth and ferromagnetic resonance of yttrium iron garnet thin films on Yiyan Sun, Young-Yeal Song, and Mingzhong Wu  

E-Print Network [OSTI]

doped TbMnO3 thin films grown by pulsed laser deposition J. Appl. Phys. 112, 033914 (2012) Structural. Phys. Lett. 101, 033910 (2012) Ge2Sb2Te5 phase-change films on polyimide substrates by pulsed laser and two thin cladding layers. The cladding layers were high entropy alloy nitrides (HEAN) and served

226

Tungsten oxide (WO{sub 3}) thin films for application in advanced energy systems  

SciTech Connect (OSTI)

Inherent processes in coal gasification plants produce hazardous hydrogen sulfide (H{sub 2}S), which must be continuously and efficiently detected and removed before the fuel is used for power generation. An attempt has been made in this work to fabricate tungsten oxide (WO{sub 3}) thin films by radio-frequency reactive magnetron-sputter deposition. The impetus being the use of WO{sub 3} films for H{sub 2}S sensors in coal gasification plants. The effect of growth temperature, which is varied in the range of 30-500 deg. C, on the growth and microstructure of WO{sub 3} thin films is investigated. Characterizations made using scanning electron microscopy (SEM) and x-ray diffraction (XRD) indicate that the effect of temperature is significant on the microstructure of WO{sub 3} films. XRD and SEM results indicate that the WO{sub 3} films grown at room temperature are amorphous, whereas films grown at higher temperatures are nanocrystalline. The average grain-size increases with increasing temperature. WO{sub 3} films exhibit smooth morphology at growth temperatures {<=}300 deg. C while relatively rough at >300 deg. C. The analyses indicate that the nanocrystalline WO{sub 3} films grown at 100-300 deg. C could be the potential candidates for H{sub 2}S sensor development for application in coal gasification systems.

Gullapalli, S. K.; Vemuri, R. S.; Manciu, F. S.; Enriquez, J. L.; Ramana, C. V. [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States); Department of Physics, University of Texas at El Paso, El Paso, Texas 79968 (United States); Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)

2010-07-15T23:59:59.000Z

227

Epitaxial strain effect on the Jeff = 1/2 moment orientation in Sr2IrO4 thin films  

Science Journals Connector (OSTI)

We have grown Sr2IrO4 (SIO) epitaxial thin films on SrTiO3 (STO) and NdGaO3 (NGO) substrates by a pulsed laser deposition method and characterized their structures and magnetic properties. We find that SIO films grown on STO substrates display tetragonal structure with a tensile strain of 0.13%, while SIO films grown on NGO substrates exhibit slightly orthorhombic structure with anisotropic biaxial tensile strains of 0.39% and 0.51% along the in-plane crystallographic axes. Although both films display insulating properties as bulk SIO does, their magnetic properties are distinct from that of bulk SIO. The ferromagnetic (FM) component of the Jeff = 1/2 canted antiferromagnetic order, which emerges below ?240 K in bulk SIO, is significantly weakened in both films, with a greater weakening appearing in the SIO/NGO film. From structural and magnetoresistance anisotropy analyses for both films, we reveal that the weak FM component in SIO films is dependent on the epitaxial strain. The greater tensile strain leads to a smaller octahedral rotation: The rotation angle is ?9.7(1)° for the SIO/NGO film and ?10.7(2)° for the SIO/STO film. These findings indicate that the Jeff = 1/2 moment orientation in SIO follows the IrO6 octahedral rotation due to strong spin-orbit interaction.

Ludi Miao; Hong Xu; Z. Q. Mao

2014-01-08T23:59:59.000Z

228

Direct Measurement of Ion Beam Induced, Nanoscale Roughening of GaN Bentao Cui and P. I. Cohen  

E-Print Network [OSTI]

Direct Measurement of Ion Beam Induced, Nanoscale Roughening of GaN Bentao Cui and P. I. Cohen of a surface roughening term due to curvature-dependent sputtering or asymmetric attachment of vacancies change using atomic force microscopy, we show a method to measure the ion-roughening coefficient. Using

Cohen, Philip I.

229

K.K. Gan US ATLAS Pixel R&D Meeting 1 Results of Opto-Link R&D  

E-Print Network [OSTI]

&D Meeting 11 K.K. Gan 11 VCSEL Power vs Dosage AOC (5 & 10 Gb/s) survive to SLHC dosage 2007: Two arraysLight, Hamamatsu (new) GaAs: AOC, ULM, Optowell, Hamamatsu (new) VCSEL: AOC, Optowell, ULM

Gan, K. K.

230

Sensors and Actuators B 105 (2005) 329333 Remote sensing system for hydrogen using GaN Schottky diodes  

E-Print Network [OSTI]

including detection of combustion gases, for fuel leak detection in spacecraft, automobiles and aircraft satellites require thermal radiators to dissipate heat generated by the spacecraft elec- tronics hydrogen and hydrocarbons [1,7,24,25]. Gas sensors based on GaN could be integrated with high

Florida, University of

231

Role of Embedded Clustering in Dilute Magnetic Semiconductors: Cr Doped GaN X. Y. Cui,1  

E-Print Network [OSTI]

, typically 5 (20­30) times smaller for Cr-based (Mn-based) III-V DMS than the value expected, 3 B= Cr4 BRole of Embedded Clustering in Dilute Magnetic Semiconductors: Cr Doped GaN X. Y. Cui,1 J. E configurations coexist and the statistical distribution and associated magnetism will depend sensitively

Medvedeva, Julia E.

232

First-principles calculations of the structural and electronic properties of clean GaN(0001) surfaces  

Science Journals Connector (OSTI)

We employ density-functional theory (DFT) within the local-density approximation (LDA) and generalized-gradient approximation (GGA) to study structural and electronic properties of clean GaN(0001) surfaces. The pseudopotential method is used to investigate surfaces with (1×1), (2×2), and (3×3)R30° reconstructions. We also report calculations for the N2 molecule and for the bulk phases of Ga and GaN. We find that GGA give better results than LDA for the cohesive energies, but not for the structural properties. Bulk band structures are found to be very similar for both exchange-correlation potentials. Examining the clean GaN(0001) surfaces we conclude that both potentials give very similar relaxations and an almost identical dispersion for the surface states. We also report results for ionization energies, electron affinities, and work function for the GaN(0001) surfaces. As a general trend the ionization energy decreases monotonically with the increasing of the Ga-coverage.

A. L. Rosa and J. Neugebauer

2006-05-25T23:59:59.000Z

233

Substrate effects on the formation of flat Ag films on (110) surfaces of III-V compound semiconductors  

Science Journals Connector (OSTI)

Ag films grown at 135 K on (110) surfaces of III-V compound semiconductors and annealed at room temperature are investigated by scanning tunneling microscopy and low-energy electron diffraction. Ag films on Ga-V semiconductors are well ordered, atomically flat, and exhibit a specific critical thickness, which is a function of the substrate material. Films grown on In-V semiconductors are still rather flat, but significantly more disordered. The (111) oriented Ag films on III-arsenides and III-phosphides exhibit a clear twofold superstructure. Films on III-antimonides exhibit threefold low-energy electron diffraction images. The morphology of the Ag films can be explained on the basis of the electronic growth mechanism.

K.-J. Chao, Zhenyu Zhang, Ph. Ebert, and C. K. Shih

1999-08-15T23:59:59.000Z

234

Magnetization dynamics of cobalt grown on graphene  

SciTech Connect (OSTI)

Ferromagnetic resonance (FMR) spin pumping is a rapidly growing field which has demonstrated promising results in a variety of material systems. This technique utilizes the resonant precession of magnetization in a ferromagnet to inject spin into an adjacent non-magnetic material. Spin pumping into graphene is attractive on account of its exceptional spin transport properties. This article reports on FMR characterization of cobalt grown on chemical vapor deposition graphene and examines the validity of linewidth broadening as an indicator of spin pumping. In comparison to cobalt samples without graphene, direct contact cobalt-on-graphene exhibits increased FMR linewidth—an often used signature of spin pumping. Similar results are obtained in Co/MgO/graphene structures, where a 1?nm MgO layer acts as a tunnel barrier. However, magnetometry, magnetic force microscopy, and Kerr microscopy measurements demonstrate increased magnetic disorder in cobalt grown on graphene, perhaps due to changes in the growth process and an increase in defects. This magnetic disorder may account for the observed linewidth enhancement due to effects such as two-magnon scattering or mosaicity. As such, it is not possible to conclude successful spin injection into graphene from FMR linewidth measurements alone.

Berger, A. J.; White, S. P.; Adur, R.; Pu, Y.; Hammel, P. C., E-mail: hammel@physics.osu.edu [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Amamou, W. [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Kawakami, R. K. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States)

2014-05-07T23:59:59.000Z

235

Investigation of the optical properties of MoS{sub 2} thin films using spectroscopic ellipsometry  

SciTech Connect (OSTI)

Spectroscopic ellipsometry (SE) characterization of layered transition metal dichalcogenide (TMD) thin films grown by vapor phase sulfurization is reported. By developing an optical dispersion model, the extinction coefficient and refractive index, as well as the thickness of molybdenum disulfide (MoS{sub 2}) films, were extracted. In addition, the optical band gap was obtained from SE and showed a clear dependence on the MoS{sub 2} film thickness, with thinner films having a larger band gap energy. These results are consistent with theory and observations made on MoS{sub 2} flakes prepared by exfoliation, showing the viability of vapor phase derived TMDs for optical applications.

Yim, Chanyoung; O'Brien, Maria; Winters, Sinéad [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); McEvoy, Niall [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Mirza, Inam; Lunney, James G. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Duesberg, Georg S., E-mail: duesberg@tcd.ie [School of Chemistry, Trinity College Dublin, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Advanced Materials and BioEngineering Research (AMBER) Centre, Trinity College Dublin, Dublin 2 (Ireland)

2014-03-10T23:59:59.000Z

236

Growth, structure and electrical properties of epitaxial thulium silicide thin films on silicon  

SciTech Connect (OSTI)

Thulium silicide thin films were grown on (100) and (111) Si by evaporation of Tm metal and Si layers and annealing in a vacuum. Electron microscopy and x-ray diffraction results showed that the TmSi{sub 2{minus}x} layers are of high crystalline quality grown epitaxially on Si. Electrical resistivity measurements showed that TmSi{sub 2{minus}x} layers are metallic exhibiting magnetic ordering below 3 K. {copyright} {ital 1997 American Institute of Physics.}

Travlos, A.; Salamouras, N.; Boukos, N. [Institute of Materials Science, National Centre for Scientific Research Demokritos, Athens, (Greece) 15310] [Institute of Materials Science, National Centre for Scientific Research Demokritos, Athens, (Greece) 15310

1997-02-01T23:59:59.000Z

237

Effects of surface treatment using aqua regia solution on the change of surface band bending of p-type GaN  

Science Journals Connector (OSTI)

Effects of surface treatment on the change of band bending at the surface of p-type GaN were studied using ... interpret the reduction of contact resistivity by the surface treatment. The contact resistivity on p...

Jong Kyu Kim; Ki-Jeong Kim; Bongsoo Kim; Jae Nam Kim…

2001-01-01T23:59:59.000Z

238

Optical polarization anisotrop in nonpolar GaN thin films due to crystal symmetry and anisotropic strain.  

E-Print Network [OSTI]

??Diese Arbeit befasst sich mit den optischen Eigenschaften von dünnen GaN-Schichten gewachsen in verschiedenen Orientierungen. Hierbei werden die optischen Eigenschaften von verspannten M- und A-plane… (more)

Misra, Pranob

2006-01-01T23:59:59.000Z

239

Growth of Epitaxial gamma-Al2O3 Films on Rigid Single-Crystal Ceramic Substrates and Flexible, Single-Crystal-Like Metallic Substrates by Pulsed Laser Deposition  

SciTech Connect (OSTI)

Epitaxial -Al2O3 thin films were grown on diverse substrates using pulsed laser deposition. The high quality of epitaxial growth and cubic structure of -Al2O3 films was confirmed by x-ray diffraction. SrTiO3 and MgO single crystal substrates were used to optimize the growth conditions for epitaxial -Al2O3 film. Under the optimized conditions, epitaxial -Al2O3 thin films were grown on flexible, single-crystal-like, metallic templates. These included untextured Hastelloy substrates with a biaxially textured MgO layer deposited using ion-beam-assisted-deposition and biaxially textured Ni-W metallic tapes with epitaxially grown and a biaxially textured, MgO buffer layer. These biaxially textured, -Al2O3 films on flexible, single-crystal-like substrates are promising for subsequent epitaxial growth of various complex oxide films used for electrical, magnetic and electronic device applications.

Shin, Junsoo [ORNL; Goyal, Amit [ORNL; Wee, Sung Hun [ORNL

2009-01-01T23:59:59.000Z

240

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

SciTech Connect (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

Note: This page contains sample records for the topic "gan films grown" from the National Library of EnergyBeta (NLEBeta).
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241

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

SciTech Connect (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

242

Thermal Conductivity in Nanocrystalline Ceria Thin Films  

SciTech Connect (OSTI)

The thermal conductivity of nanocrystalline ceria films grown by unbalanced magnetron sputtering is determined as a function of temperature using laser-based modulated thermoreflectance. The films exhibit significantly reduced conductivity compared with stoichiometric bulk CeO2. A variety of microstructure imaging techniques including X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron analysis, and electron energy loss spectroscopy indicate that the thermal conductivity is influenced by grain boundaries, dislocations, and oxygen vacancies. The temperature dependence of the thermal conductivity is analyzed using an analytical solution of the Boltzmann transport equation. The conclusion of this study is that oxygen vacancies pose a smaller impediment to thermal transport when they segregate along grain boundaries.

Marat Khafizov; In-Wook Park; Aleksandr Chernatynskiy; Lingfeng He; Jianliang Lin; John J. Moore; David Swank; Thomas Lillo; Simon R. Phillpot; Anter El-Azab; David H. Hurley

2014-02-01T23:59:59.000Z

243

Thin-film tin oxideâ??ethanol sensor  

Science Journals Connector (OSTI)

Tin Oxide (SnO2) thin films grown on glass substrate at 648 K using direct evaporation method with two gold pads deposited on the top for electrical contacts were exposed to ethanol vapours (200-1000 ppm). The operating temperature of the sensor was optimised. The sensitivity variation of films having different thicknesses was studied. To improve the sensitivity and selectivity further, a thin layer of metal oxide was deposited on the sensor surface to work as a catalytic layer and its effect on the performance of the sensor was studied. The response and recovery times of the sensor were determined.

H.J. Pandya

2009-01-01T23:59:59.000Z

244

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

245

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

246

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

SciTech Connect (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

247

Effect of copper doping on structural, optical and electrical properties of Cd0·8Zn0·2S films prepared by chemical bath deposition  

Science Journals Connector (OSTI)

Cd 0·8Zn 0·2S:Cu films of 1 ·3–6 ·1 mole percentage of copper have been grown on mica substrate by using chemical bath deposition technique. The films have been characterized by using XRD, SEM and UV spectrophoto...

K HADASA; G YELLAIAH; M NAGABHUSHANAM

2014-02-01T23:59:59.000Z

248

Investigation of the evolution of single domain ,,111...B CdTe films by molecular beam epitaxy on miscut ,,001...Si substrate  

E-Print Network [OSTI]

Investigation of the evolution of single domain ,,111...B CdTe films by molecular beam epitaxy; accepted for publication 22 July 1998 A comprehensive view of the microstructure of 111 B CdTe films grown and scanning transmission electron microscopy. It is found that in the initial growth stage, CdTe nucleates

Pennycook, Steve

249

Correlation Between Optical Properties And Chemical Composition Of Sputter-deposited Germanium Cxide (GeOx) Films  

SciTech Connect (OSTI)

Germanium oxide (GeOx) films were grown on (1 0 0) Si substrates by reactive Direct-Current (DC) magnetron sputter-deposition using an elemental Ge target. The effects of oxygen gas fraction, ? = O2/(Ar + O2), on the deposition rate, structure, chemical composition and optical properties of GeOx films have been investigated. The chemistry of the films exhibits an evolution from pure Ge to mixed Ge + GeO + GeO2 and then finally to GeO2 upon increasing ? from 0.00 to 1.00. Grazing incidence X-ray analysis indicates that the GeOx films grown were amorphous. The optical properties probed by spectroscopic ellipsometry indicate that the effect of ? is significant on the optical constants of the GeOx films. The measured index of refraction (n) at a wavelength (?) of 550 nm is 4.67 for films grown without any oxygen, indicating behavior characteristic of semiconducting Ge. The transition from germanium to mixed Ge + GeO + GeO2 composition is associated with a characteristic decrease in n (? = 550 nm) to 2.62 and occurs at ? = 0.25. Finally n drops to 1.60 for ? = 0.50–1.00, where the films become GeO2. A detailed correlation between ?, n, k and stoichiometry in DC sputtered GeOx films is presented and discussed.

Murphy, Neil R.; Grant, J. T.; Sun, L.; Jones, J. G.; Jakubiak, R.; Shutthanandan, V.; Ramana, Chintalapalle V.

2014-03-18T23:59:59.000Z

250

Study of gain and photoresponse characteristics for back-illuminated separate absorption and multiplication GaN avalanche photodiodes  

SciTech Connect (OSTI)

The gain and photoresponse characteristics have been numerically studied for back-illuminated separate absorption and multiplication (SAM) GaN avalanche photodiodes (APDs). The parameters of fundamental models are calibrated by simultaneously comparing the simulated dark and light current characteristics with the experimental results. Effects of environmental temperatures and device dimensions on gain characteristics have been investigated, and a method to achieve the optimum thickness of charge layer is obtained. The dependence of gain characteristics and breakdown voltage on the doping concentration of the charge layer is also studied in detail to get the optimal charge layer. The bias-dependent spectral responsivity and quantum efficiency are then presented to study the photoresponse mechanisms inside SAM GaN APDs. It is found the responsivity peak red-shifts at first due to the Franz-Keldysh effect and then blue-shifts due to the reach-through effect of the absorption layer. Finally, a new SAM GaN/AlGaN heterojunction APD structure is proposed for optimizing SAM GaN APDs.

Wang, Xiaodong; Pan, Ming; Hou, Liwei; Xie, Wei [No. 50 Research Institute of China Electronics Technology Group Corporation, 200331 Shanghai (China); Hu, Weida, E-mail: wdhu@mail.sitp.ac.cn; Xu, Jintong; Li, Xiangyang; Chen, Xiaoshuang, E-mail: xschen@mail.sitp.ac.cn; Lu, Wei [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 200083 Shanghai (China)

2014-01-07T23:59:59.000Z

251

Photonic Crystal Cavities in Cubic Polytype Silicon Carbide Films  

E-Print Network [OSTI]

We present the design, fabrication, and characterization of high quality factor and small mode volume planar photonic crystal cavities from cubic (3C) thin films (thickness ~ 200 nm) of silicon carbide (SiC) grown epitaxially on a silicon substrate. We demonstrate cavity resonances across the telecommunications band, with wavelengths from 1250 - 1600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

Radulaski, Marina; Buckley, Sonia; Rundquist, Armand; Provine, J; Alassaad, Kassem; Ferro, Gabriel; Vu?kovi?, Jelena

2013-01-01T23:59:59.000Z

252

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

SciTech Connect (OSTI)

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

253

Peculiarly strong room-temperature ferromagnetism from low Mn-doping in ZnO grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO thin films grown by molecular beam epitaxy. Very low Mn doping concentration is investigated, and the measured magnetic moment is much larger than what is expected for an isolated ion based on Hund's rules. The ferromagnetic behavior evolves with Mn concentration. Both magnetic anisotropy and anomalous Hall effect confirm the intrinsic nature of ferromagnetism. While the Mn dopant plays a crucial role, another entity in the system is needed to explain the observed large magnetic moments.

Zuo Zheng; Morshed, Muhammad; Liu Jianlin [Quantum Structures Laboratory, Department of Electrical Engineering, University of California at Riverside, Riverside, California 92521 (United States); Beyermann, W. P. [Department of Physics and Astronomy, University of California at 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, FL 32310-3706 (United States)

2013-03-15T23:59:59.000Z

254

Physical properties and band structure of reactive molecular beam epitaxy grown oxygen engineered HfO{sub 2{+-}x}  

SciTech Connect (OSTI)

We have conducted a detailed thin film growth structure of oxygen engineered monoclinic HfO{sub 2{+-}x} grown by reactive molecular beam epitaxy. The oxidation conditions induce a switching between (111) and (002) texture of hafnium oxide. The band gap of oxygen deficient hafnia decreases with increasing amount of oxygen vacancies by more than 1 eV. For high oxygen vacancy concentrations, defect bands form inside the band gap that induce optical transitions and p-type conductivity. The resistivity changes by several orders of magnitude as a function of oxidation conditions. Oxygen vacancies do not give rise to ferromagnetic behavior.

Hildebrandt, Erwin; Kurian, Jose; Alff, Lambert [Institute of Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany)

2012-12-01T23:59:59.000Z

255

GaNAsP: An intermediate band semiconductor grown by gas-source molecular beam epitaxy  

SciTech Connect (OSTI)

Dilute nitride GaNAsP thin films were grown via a GaAsP metamorphic buffer on GaP(100) substrate with gas-source molecular beam epitaxy. The compositions of this III-V-V-V compound were determined by channeling Rutherford backscattering spectroscopy and nuclear reaction analysis. Photoreflectance shows two distinctive transitions from the valence band to the split conduction bands due to N incorporation. Photoluminescence and optical absorption show the fundamental bandgap of Ga(N)AsP is largely tailored by the small amount of N. The observed multiband characteristics and the bandgap tunability of GaNAsP are two merits that fit into the intermediate-band solar cell roadmap, and GaNAsP of high crystal quality provides a strong candidate for intermediate band solar cell materials.

Kuang, Y. J. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Yu, K. M.; Walukiewicz, W. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kudrawiec, R. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Institute of Physics, Wroclaw University of Technology, Wybrzeze, Wyspianskiego 27, 50-370 Wroclaw (Poland); Luce, A. V. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Ting, M. [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Tu, C. W. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2013-03-18T23:59:59.000Z

256

Effect of substrate temperature on crystal orientation and residual stress in radio frequency sputtered gallium–nitride films  

Science Journals Connector (OSTI)

The crystal orientation and residual stress in gallium nitride(GaN)filmsdeposited on a single-crystal (0001) sapphire substrate using a sputtering system are examined through x-ray diffraction measurements as part of a study of low-temperaturesputtering techniques for GaN. The rf sputtering system has an isolated deposition chamber to prevent contamination with impurities and is expected to produce high-purity nitride films.GaNfilms are deposited at various substrate temperatures and constant gas pressure and input power. This system is found to produce GaNfilms with good crystal orientation with the c axes of GaN crystals oriented normal to the substrate surface. The crystal size of filmsdeposited at high temperature is larger than that deposited at low T s . All films except that deposited at 973 K exhibit compressive residual stress and this residual stress is found to decrease with increasing temperature. Finally the filmdeposited at 973 K was tinged with white and the surface contained numerous microcracks.

Kazuya Kusaka; Takao Hanabusa; Kikuo Tominaga; Noriyoshi Yamauchi

2004-01-01T23:59:59.000Z

257

Modification of epitaxial oxide films with ion implantation  

SciTech Connect (OSTI)

Ion implantation is used to modify the properties of oxide (YBCO and YSZ) thin films. Both superconducting and dielectric epitaxial oxide films, grown by laser ablation, are studied. The properties of the implanted oxide films are characterized by SIMS, XPS, DC resistivity and AC susceptibility measurements. By introducing reactive ions into superconducting oxide films, the conductivity of the material is inhibited possibly due to the interaction of the implanted ions with oxygen originally bound to the copper atoms. Al, Si, Ag and Ca ions are implanted into epitaxial YBCO films with injection energies ranging from 50--100 KeV and doses ranging from 1 {times} 10{sup 15}--1 {times} 10{sup 16}/cm{sup 2}. XPS analysis shows that the implanted Si ions form SiO{sub x}. The inhibition method has been applied to the fabrication of superconducting electronic devices, such as SQUIDs. Dielectric oxide films are doped by the implantation of conductive and nonconductive ions. YSZ films are doped with Ag and Si ions and the ions are found to increase the conductivity.

Hong, S.H.; Miller, J.R.; Ma, Q.Y.; Yang, E.S. [Columbia Univ., New York, NY (United States). Dept. of Electrical Engineering; Fenner, D.B. [AFR Inc., East Hartford, CT (United States); Yang, C.Y. [Santa Clara Univ., CA (United States). Microelectronics Lab.; Budnick, J.I. [Univ. of Connecticut, Storrs, CT (United States). Dept. of Physics

1996-11-01T23:59:59.000Z

258

Microstructure of highly strained BiFeO{sub 3} thin films: Transmission electron microscopy and electron-energy loss spectroscopy studies  

SciTech Connect (OSTI)

Microstructure and electronic structure of highly strained bismuth ferrite (BiFeO{sub 3}) thin films grown on lanthanum aluminate substrates are studied using high-resolution transmission and scanning transmission electron microscopies and electron energy loss spectroscopy (EELS). Monoclinic and tetragonal phases were observed in films grown at different temperatures, and a mix of both phases was detected in a film grown at intermediate temperature. In this film, a smooth transition of the microstructure was found between the monoclinic and the tetragonal phases. A considerable increase in the c-axis parameters was observed in both phases compared with the rhombohedral bulk phase. The off-center displacement of iron (Fe) ions was increased in the monoclinic phase as compared with the tetragonal phase. EEL spectra show different electronic structures in the monoclinic and the tetragonal phases. These experimental observations are well consistent with the results of theoretical first-principle calculations performed.

Heon Kim, Young, E-mail: young.h.kim@kriss.re.kr [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); Korea Research Institute of Standards and Science (KRISS), Daejeon 305-340 (Korea, Republic of); Bhatnagar, Akash; Pippel, Eckhard; Hesse, Dietrich [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); Alexe, Marin [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); University of Warwick, Coventry CV4 7AL, West Midlands (United Kingdom)

2014-01-28T23:59:59.000Z

259

In situ growth of p and n-type graphene thin films and diodes by pulsed laser deposition  

SciTech Connect (OSTI)

We report the in situ growth of p and n-type graphene thin films by ultraviolet pulsed laser deposition in the presence of argon and nitrogen, respectively. Electron microscopy and Raman studies confirmed the growth, while temperature dependent electrical conductivity and Seebeck coefficient studies confirmed the polarity type of graphene films. Nitrogen doping at different sites of the honeycomb structure, responsible for n-type conduction, is identified using X-ray photoelectron spectroscopy, for films grown in nitrogen. A diode-like rectifying behavior is exhibited by p-n junction diodes fabricated using the graphene films.

Sarath Kumar, S. R.; Nayak, Pradipta K.; Hedhili, M. N.; Khan, M. A.; Alshareef, H. N., E-mail: husam.alshareef@kaust.edu.sa [Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia)

2013-11-04T23:59:59.000Z

260

Polar Kerr-effect observation of perpendicular surface anisotropy for ultrathin ferromagnetic films: Fcc Fe/Cu(100)  

SciTech Connect (OSTI)

The theoretically predicted perpendicular surface anisotropy of ultrathin ferromagnetic Fe films has been confirmed using the magneto-optical Kerr effect. Polar and longitudinal Kerr-effect measurements have been performed in-situ on the same fcc Fe/Cu(100) films to study the dependence of the magnetic properties on film thickness and growth temperature conditions. Auxiliary LEED and Auger studies are used to characterize the structure and growth of the films. For films 1.2--5.9 monolayers (ML) thick grown at /approximately/100 K, for instance, square hysteresis-loop behavior in the polar Kerr effect confirmed the dominance of the perpendicular surface anisotropy. Examples are presented to document how the polar and longitudinal Kerr-effect signals evolve for films thicker than 6 ML due to the easy axis reorienting into the film plane. 14 refs., 4 figs.

Liu, C.; Moog, E.R.; Bader, S.D.

1988-05-01T23:59:59.000Z

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

Epitaxial graphene prepared by chemical vapor deposition on single crystal thin iridium films on sapphire  

E-Print Network [OSTI]

Epitaxial graphene prepared by chemical vapor deposition on single crystal thin iridium films Cedex 9, France (Dated: 15 March 2011) Uniform single layer graphene was grown on single-crystal Ir. These graphene layers have a single crystallographic orientation and a very low density of defects, as shown

Boyer, Edmond

262

Spatial distribution and magnetism in poly-Cr-doped GaN from first principles X. Y. Cui,1 J. E. Medvedeva,2 B. Delley,3 A. J. Freeman,4 and C. Stampfl1  

E-Print Network [OSTI]

Spatial distribution and magnetism in poly-Cr-doped GaN from first principles X. Y. Cui,1 J. E the spatial distribution and magnetic coupling of Cr-doped GaN, in which exhaustive structural and magnetic direct evidence that the distribution of the doped magnetic ions is neither homogeneous nor random

Medvedeva, Julia E.

263

Growth of CdTe thin films on graphene by close-spaced sublimation method  

SciTech Connect (OSTI)

CdTe thin films grown on bi-layer graphene were demonstrated by using the close-spaced sublimation method, where CdTe was selectively grown on the graphene. The density of the CdTe domains was increased with increasing the number of the defective sites in the graphene, which was controlled by the duration of UV exposure. The CdTe growth rate on the bi-layer graphene electrodes was 400?nm/min with a bandgap energy of 1.45–1.49?eV. Scanning electron microscopy, micro-Raman spectroscopy, micro-photoluminescence, and X-ray diffraction technique were used to confirm the high quality of the CdTe thin films grown on the graphene electrodes.

Jung, Younghun; Yang, Gwangseok; Kim, Jihyun, E-mail: hyunhyun7@korea.ac.kr [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Chemical and Biological Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Chun, Seungju; Kim, Donghwan [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)] [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

2013-12-02T23:59:59.000Z

264

Characterization of high quality InN grown on production-style plasma assisted molecular beam epitaxy system  

SciTech Connect (OSTI)

In this work, the authors report step-flow growth mode of InN on [0001] oriented GaN templates, using a production-style molecular beam epitaxy system, Veeco GEN200 registered , equipped with a plasma source. Using adaptive growth conditions, they have obtained a surface morphology that exhibits the step-flow features. The root mean squared roughness over an area of 5x5 {mu}m{sup 2} is 1.4 nm with monolayer height terrace steps (0.281 nm), based on atomic force microscopy. It has been found that the presence of In droplets leads to defective surface morphology. From x-ray diffraction, they estimate edge and screw dislocation densities. The former is dominant over the latter. Micro-Raman spectra reveal narrow E{sub 2}{sup 2} phonon lines consistent with excellent crystalline quality of the epitaxial layers. The Hall mobility of 1 {mu}m thick InN layers, grown in step-flow mode, is slightly higher than 1400 cm{sup 2}/V s, while for other growth conditions yielding a smooth surface with no well-defined steps, mobility as high as 1904 cm{sup 2}/V s at room temperature has been measured. The samples exhibit high intensity photoluminescence (PL) with a corresponding band edge that shifts with free carrier concentration. For the lowest carrier concentration of 5.6x10{sup 17} cm{sup -3}, they observe PL emission at {approx}0.64 eV.

Gherasoiu, I.; O'Steen, M.; Bird, T.; Gotthold, D.; Chandolu, A.; Song, D. Y.; Xu, S. X.; Holtz, M.; Nikishin, S. A.; Schaff, W. J. [Veeco Instruments Inc., MBE Operations, 4900 Constellation Drive, St. Paul, Minnesota 55127 (United States); Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14583 (United States)

2008-05-15T23:59:59.000Z

265

Electrochemical Performance of rf Magnetron Sputtered LiCoO{sub 2} Thin Film Positive Electrodes  

SciTech Connect (OSTI)

Thin films of LiCoO{sub 2} were grown by rf magnetron sputtering technique and studied the influence of In situ annealing treatment on microstructural and electrochemical properties of the films. Annealing treatment in presence of O{sub 2} ambient develops characteristic (104) plan in relative to (003) plane texture indicating that the films have HT-layered structure with R3-bar m symmetry. The effect is discussed in terms of grain size, cycling stability, reversibility and the specific discharge capacity.

Kumar, P. Jeevan; Babu, K. Jayanth; Hussain, O. M. [Thin Film Laboratory, Department of Physics, Sri Venkateswara University, TIRUPATI-517 502 (India)

2010-12-01T23:59:59.000Z

266

Serial crystallography on in vivo grown microcrystals using synchrotron radiation  

Science Journals Connector (OSTI)

The structure solution of T. brucei cathepsin B from 80 in vivo grown crystals with an average volume of 9 ?m3 obtained by serial synchrotron crystallography at a microfocus beamline is reported.

Gati, C.

2014-02-10T23:59:59.000Z

267

Self-doping effects in epitaxially grown graphene  

E-Print Network [OSTI]

The electronic properties of graphene, Rev. Mod. Phys. (inE?ects in Epitaxially-Grown Graphene D.A. Siegel, 1, 2 S.Y.2009) Abstract Self-doping in graphene has been studied by

Siegel, David A.

2009-01-01T23:59:59.000Z

268

Boron Deficiency in Cotton Grown on Calcareous Soils of Pakistan  

Science Journals Connector (OSTI)

Cotton (Gossypium hirsutum L.) in Pakistan is grown in irrigated cotton-wheat system on ~3 Mha alkaline-calcareous, alluvial soils. Despite enhanced use of nitrogen and phosphorus fertilisers, however, cotton pro...

E. Rafique; A. Rashid; A. U. Bhatti; G. Rasool…

2002-01-01T23:59:59.000Z

269

Temperature dependence of photoconductivity in Zn-doped GaN  

SciTech Connect (OSTI)

In agreement with predictions from a model that explained an abrupt thermal quenching of the blue luminescence (BL) band in high-resistivity Zn-doped GaN [Reshchikov et al., Phys. Rev. B 84, 075212 (2011) and Phys. Rev. B 85, 245203 (2012)], we observed the stepwise decrease of photoconductivity in this material with increasing temperature. For the sample studied in this work, the decrease in photoconductivity occurred in two steps at characteristic temperatures T{sub 1} and T{sub 2}. The characteristic temperatures increased with increasing excitation intensity, very similar to the photoluminescence (PL) behavior. The steps in photoconductivity at about 100 K and 200 K are attributed to drop in the concentration of free electrons due to the thermal emission of holes from a shallow acceptor and the Zn{sub Ga} acceptor, respectively, to the valence band and their recombination with electrons via nonradiative centers. This finding supports the model suggested previously and helps to explain other examples of tunable photoconductivity reported in literature.

Reshchikov, Michael A. [Department of Physics, Virginia Commonwealth University, Richmond, VA 23284 (United States)

2014-02-21T23:59:59.000Z

270

Temperature Dependent Cathodoluminescence Characterization of Ultraviolet Emitting Films Grown by Pulsed Laser Deposition  

E-Print Network [OSTI]

. Res. Soc. Symp. Proc. Vol. 780 © 2003 Materials Research Society Y1.4.1 #12;Of the MS:Te systems, CdS of ~ 4.32 eV. When doped with tellurium (Te), ultraviolet emission occurs at 360 nm (for Tes singletS- Te-SrS multi-layer structures on Si substrates. The Te doping was incorporated by conventional

Fitz-Gerald, James M.

271

Versatile Carbon Hybrid Films Composed of Vertical Carbon Nanotubes Grown on Mechanically Compliant  

E-Print Network [OSTI]

overlapping nanoclay (vermiculite,[7] mica,[8] montmorillonite, etc.) platelets, over- lapping hexagonal boron

Hong, Soon Hyung

272

E-Print Network 3.0 - aln films grown Sample Search Results  

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

and Technology Collection: Chemistry ; Materials Science 4 Correlation between optoelectronic and structural properties and epilayer thickness of AlN Summary: . Similar with...

273

Engineering coercivity in epitaxially grown (110) films of DyFe 2 –YFe 2 superlattices  

Science Journals Connector (OSTI)

Molecular beam epitaxial methods have been used to growsingle crystal Laves phase DyFe 2 –YFe 2 superlattice samples with a (110) growth direction. It is shown that it is possible in principle to engineer a desired coercivity between the limits K DyFe 2 ?K??. This can be achieved by adjusting the relative thickness of the individual DyFe 2 and YFe 2 layers in multilayerfilms This novel feature is illustrated using the superlatticefilms [x?Å? DyFe 2 /(100-x)?Å? YFe 2 ]×40 with x=80 60 50 and 45. It is found that the measured coercivity is in semiquantitative agreement with a simple theoretical expression for the nucleation fields in both bilayer and multilayer compounds. However in practice exchange spring penetration into the DyFe 2 layers can set a limit to the maximum coercivity that can be achieved.

M. Sawicki; G. J. Bowden; P. A. J. de Groot; B. D. Rainford; J. M. L. Beaujour; R. C. C. Ward; M. R. Wells

2000-01-01T23:59:59.000Z

274

A liquid film motor  

Science Journals Connector (OSTI)

It is well known that electro-hydrodynamical effects in freely suspended liquid films can force liquids to flow. Here, we report a purely electrically driven rotation in water and some other liquid suspended film...

A. Amjadi; R. Shirsavar; N. Hamedani Radja…

2009-05-01T23:59:59.000Z

275

Rapid Research Note Raman Scattering in Resonance  

E-Print Network [OSTI]

-uniformity in the ternary alloy InGaN [4, 5]. However, resonance Raman scattering at bound excitons as reported for CdS doped 220 mm thick GaN film grown by hydride vapor phase epitaxy. Sapphire (0001) with a sputtered Zn

Nabben, Reinhard

276

physica status solidi 1 Rapid Research Note To be published in: phys. stat. sol. (b) 223, No. 3 (2001)  

E-Print Network [OSTI]

-uniformity in the ternary alloy InGaN [4, 5]. However, resonance Raman scattering at bound excitons as reported for CdS doped 220 µm thick GaN film grown by hydride vapor phase epitaxy. Sapphire (0001) with a sputtered Zn

Nabben, Reinhard

277

2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim p s scurrent topics in solid state physics  

E-Print Network [OSTI]

directing elements for light emitting devices. Many recent activities in the NSAG field have focused on Ga. Comparison of the stress properties between the nanodots, nanostripes, and continu- ous GaN film grown by metal organic vapor phase epitaxy. By varying the growth reactor pressure, we have been able to grow

Sirenko, Andrei

278

Synthesis of diamondlike carbon films with superlow friction and wear properties  

SciTech Connect (OSTI)

In this study, the authors introduce a new diamondlike carbon (DLC) film providing a friction coefficient of 0.001 and wear rates of 10{sup {minus}9} to 10{sup {minus}10} mm{sup 3}/N.m in inert-gas environments (e.g., dry nitrogen and argon). The film was grown on steel and sapphire substrates in a plasma enhanced chemical vapor deposition system that uses using a hydrogen-rich plasma. Employing a combination of surface and structure analytical techniques, they explored the structural chemistry of the resultant DLC films and correlated these findings with the friction and wear mechanisms of the films. The results of tribological tests under a 10-N load (creating initial peak Hertz pressures of 1 and 2.2 GPa on steel and sapphire test pairs, respectively) and at 0.2 to 0.5 m/s sliding velocities indicated that a close correlation exists between the friction and wear coefficients of DLC films and the source gas chemistry. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios had the lowest fiction coefficients and the highest wear resistance. The lowest friction coefficient (0.001) was achieved with a film on sapphire substrates produced in a gas discharge plasma consisting of 25% methane and 75% hydrogen.

Erdemir, A.; Eryilmaz, O. L.; Fenske, G.

2000-01-19T23:59:59.000Z

279

Modified Magnetic Ground State in Nimn (2) O (4) Thin Films  

SciTech Connect (OSTI)

The authors demonstrate the stabilization of a magnetic ground state in epitaxial NiMn{sub 2}O{sub 4} (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and epitaxial strain are ruled out as possible causes for the new magnetic ground state in the as-grown films. However, a decrease in the octahedral Mn{sup 4+}:Mn{sup 3+} concentration is observed and likely disrupts the double exchange that produces the magnetic state at intermediate temperatures. X-ray magnetic circular dichroism and bulk magnetometry indicate a canted ferrimagnetic state in all samples at low T. Together these results suggest that the collinear ferrimagnetic state observed in bulk NMO at intermediate temperatures is suppressed in the as grown NMO thin films due to a decrease in octahedral Mn{sup 4+}, while the canted moment ferrimagnetic ordering is preserved below 60 K.

Nelson-Cheeseman, B.B.; Chopdekar, R.V.; Iwata, J.M.; Toney, M.F.; Arenholz, E.; Suzuki, Y.; /SLAC

2012-08-23T23:59:59.000Z

280

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

SciTech Connect (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

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.


281

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

SciTech Connect (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

282

Alloy decomposition and surface instabilities in thin films  

Science Journals Connector (OSTI)

We show that in the presence of substrate misfit and compositional stresses, static or growing films that undergo surface spinodal decomposition are always unstable to perturbations around the planar surface. For sufficiently rapid deposition processes, the planar surface can be stabilized due to a suppression of the alloy decomposition. Films grown outside of the miscibility gap can become unstable due to the mismatch with the substrate and compositionally generated stresses. We also demonstrate that the instability is independent of the sign of the misfit when the elastic moduli of the alloy constituents are equal, and the existence of a maximum misfit above which the film is always unstable, even at high growth rates. The symmetry under sign reversal of the misfit can be broken by composition-dependent elastic constants.

François Léonard and Rashmi C. Desai

1998-02-15T23:59:59.000Z

283

Order on disorder: Copper phthalocyanine thin films on technical substrates  

SciTech Connect (OSTI)

We have studied the molecular orientation of the commonly used organic semiconductor copper phthalocyanine (CuPC) grown as thin films on the technically relevant substrates indium tin oxide, oxidized Si, and polycrystalline gold using polarization-dependent x-ray absorption spectroscopy, and compare the results with those obtained from single crystalline substrates [Au(110) and GeS(001)]. Surprisingly, the 20{endash}50 nm thick CuPC films on the technical substrates are as highly ordered as on the single crystals. Importantly, however, the molecular orientation in the two cases is radically different: the CuPC molecules stand on the technical substrates and lie on the single crystalline substrates. The reasons for this and its consequences for our understanding of the behavior of CuPC films in devices are discussed. {copyright} 2001 American Institute of Physics.

Peisert, H.; Schwieger, T.; Auerhammer, J. M.; Knupfer, M.; Golden, M. S.; Fink, J.; Bressler, P. R.; Mast, M.

2001-07-01T23:59:59.000Z

284

Preparation of silicon carbide film by a plasma focus device  

Science Journals Connector (OSTI)

Silicon carbide (SiC) films were grown on the silicon (100) substrate by a 20 kJ Mather-type dense plasma focus device. The preparation method and characterization data are presented. X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM) and nano-indentor were employed for the characterization of the samples obtained at different axial position of 50 mm, 90 mm, 130 mm and 170 mm, respectively. Polycrystalline 3CSiC were obtained at the position of 90 mm and 130 mm from XRD and FTIR spectra. SEM image showed that the silicon carbide films obtained at the position of 90 mm are porous on surface layer. Nano-indentor indicates that the film obtained at the position of 130 mm has the highest mechanical hardness.

Z.P. Wang; H.R. Yousefi; Y. Nishino; H. Ito; K. Masugata

2008-01-01T23:59:59.000Z

285

Langmuir-Blodgett films  

Science Journals Connector (OSTI)

...thwart practical applications of Langmuir-Blodgett...design of organic thin-film devices. AHN...thwart practical applications of Langmuir-Blodgett...design of organic thin-film devices. | Department...course, as in all thin film techniques...applica-tions in optical and electronic...produced by MBE or CVD (1-4). J...

JA Zasadzinski; R Viswanathan; L Madsen; J Garnaes; DK Schwartz

1994-03-25T23:59:59.000Z

286

Electrical transport properties in nitrogen-doped p-type ZnO thin film  

Science Journals Connector (OSTI)

Electrical transport properties of p-type ZnO:N films grown by thermal activation of the nitrogen dopant were investigated via the temperature-dependent Hall effect. The Hall mobility increases with decreasing temperature. Varied scattering mechanisms have been analysed including lattice vibration scattering, ionized impurity scattering and dislocation scattering. A fit of the theory to temperature-dependent hole mobility experimental data in p-type ZnO:N films gives dislocation densities in the order of 1012 cm?2. The analysis shows dislocation scattering is indeed important for the p-type ZnO films grown on the mismatched substrate. The thermal ionization energy of the nitrogen acceptor is estimated to be 170 meV in terms of the temperature-dependent hole concentration. On the other hand, the emission related to the acceptors is observed in PL spectra.

Z Y Xiao; Y C Liu; B H Li; J Y Zhang; D X Zhao; Y M Lu; D Z Shen; X W Fan

2006-01-01T23:59:59.000Z

287

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

SciTech Connect (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

288

Growth strains and creep in thermally grown alumina : oxide growth mechanisms.  

SciTech Connect (OSTI)

In situ measurements of growth strains and creep relaxation in {alpha}-Al{sub 2}O{sub 3} films, isothermally grown on {beta}-NiAl alloys at 1100 C, are reported and analyzed. Samples containing the reactive element Zr, and Zr-free samples, are examined. For Zr-free samples, steady state growth strains are compressive, whereas the growth strains are tensile when the reactive element (RE) is added to the alloy. This behavior is attributed to the counterflow of oxygen and aluminum interstitials, and to simultaneous counterflow of oxygen and aluminum vacancies, all moving through the grain boundaries. Cross diffusing oxygen and aluminum interstitials may merge and combine within the film, forming new oxide along grain boundary walls, a mechanism that leads to an in-plane compressive stress. Cross diffusing oxygen and aluminum vacancies will also merge and combine within the film; in this case material is removed from grain boundary walls, a mechanism that leads to an in-plane tensile stress. When no RE is present, the interstitial mechanism dominates and the resultant stress is compressive. Consistent with the 'dynamic segregation model', the RE slows the outdiffusion of Al interstitials permitting the tensile mechanism to dominate. This interpretation invokes the unconventional view that oxygen and aluminum interstitials and vacancies, created in and driven by the strong chemical gradient, all participate meaningfully in the scale growth process. Grain boundary diffusion measurements were obtained from low stress creep data, interpreted using the Coble model of grain boundary diffusion. Reported diffusion measurements of oxygen through grain boundaries of {alpha}-Al{sub 2}O{sub 3}, which are known to be inconsistent with oxide scale growth, are critically examined. A simple picture, a 'balanced defect model', emerges that is consistent with the dynamic segregation model, observed growth stresses and their dependence on the presence of a reactive element, sequential oxidation experiments, and our best knowledge about grain boundary diffusion coefficients.

Veal, B. W.; Paulikas, A. P.; Materials Science Division

2008-01-01T23:59:59.000Z

289

Evaluation of growth methods for the heteroepitaxy of non-polar (11-20) GaN on sapphire by MOVPE  

E-Print Network [OSTI]

double grating spectrometer equipped with a Peltier-cooled GaAs photomultiplier tube. The spectra were recorded with signal lock-in processing techniques. As the HeCd laser absorption length is ca. 350 nm for 99% absorption in GaN (ignoring any carrier... double grating spectrometer equipped with a Peltier-cooled GaAs photomultiplier tube. The spectra were recorded with signal lock-in processing techniques. As the HeCd laser absorption length is ca. 350 nm for 99% absorption in GaN (ignoring any carrier...

Oehler, F.; Sutherland, D.; Zhu, T.; Emery, R.; Badcock, T. J.; Kappers, M. J.; Humphreys, C. J.; Dawson, P.; Oliver, R. A.

2014-09-16T23:59:59.000Z

290

Nitrogen doping in pulsed laser deposited ZnO thin films using dense plasma focus  

Science Journals Connector (OSTI)

Pulsed laser deposition synthesized ZnO thin films, grown at 400 °C substrate temperature in different oxygen gas pressures, were irradiated with 6 shots of pulsed nitrogen ions obtained from 2.94 kJ dense plasma focus to achieve the nitrogen doping in ZnO. Structural, compositional and optical properties of as-deposited and nitrogen ion irradiated ZnO thin films were investigated to confirm the successful doping of nitrogen in irradiated samples. Spectral changes have been seen in the nitrogen irradiated ZnO thin film samples from the low temperature PL measurements. Free electron to acceptor emissions can be observed from the irradiated samples, which hints towards the successful nitrogen doping in films. Compositional analysis by X-ray photoelectron spectroscopy and corresponding shifts in binding energy core peaks of oxygen and nitrogen confirmed the successful use of plasma focus device as a novel source for nitrogen ion doping in ZnO thin films.

S. Karamat; R.S. Rawat; T.L. Tan; P. Lee; S.V. Springham; E. Ghareshabani; R. Chen; H.D. Sun

2011-01-01T23:59:59.000Z

291

Electrochemically controlled pitting corrosion in Ni film: A study of AFM and neutron reflectometry  

Science Journals Connector (OSTI)

Electrochemical behavior of pitting corrosion of a Ni film, grown on Si substrate by sputtering, prepassivated in a chloride-free sulfuric acid solution and subsequently exposed to chloride above the pitting potential is reported. Specular and off-specular unpolarized neutron reflectometry and Atomic Force Microscopy (AFM) techniques have been used to determine the depth profile of scattering length density and morphology of as-deposited as well as corroded sample. Specular neutron reflectometry measurement of the film after corrosion shows density degradation along the thickness of film. The density profile as a function of depth, maps the growth of pitting and void networks due to corrosion. The AFM and off-specular neutron reflectivity measurements has suggested that the morphology of the film remains same after exposure of the film in chloride solution.

Surendra Singh; Saibal Basu; A.K. Poswal; R.B. Tokas; S.K. Ghosh

2009-01-01T23:59:59.000Z

292

K.K. Gan US ATLAS Pixel Upgrade Workshop 1 Results of LHC & SLHC Opto-Link R&D  

E-Print Network [OSTI]

-Hardness of GaAs PIN AOC ULM irradiate PIN with 24 GeV protons at CERN SLHC dosage: 2.6 x 1015 p/cm2 (8.2 x study? Gb/s Responsivity (A/W) GaAs Pre Post ULM 4.25 0.50 0.13 AOC 2.5 0.60 0.19 Optowell 3.125 0.60 0 dosage: AOC(5 & 10 G) have good power #12;K.K. Gan US ATLAS Pixel Upgrade Workshop 8 Opto-Chips 1

Gan, K. K.

293

Laser diagnostics of CVD diamond film growth  

SciTech Connect (OSTI)

Diamond has one of hte most exciting combinations of properties known.{sup 1} It is the hardest material known, has extremely high thermal conductivity, wide optical transparency, and a durability that is unmatched by other substances. The scarcity and high cost of natural diamond has precluded its use in many potential applications that would benefit from this unique combination of properties. Over the last two decades, the technique of chemical vapor deposition (CVD) of diamond at low pressure has been developed, providing the technology to produce thin and thick film coatings on a variety of materials as well as freestanding films and plates of diamond. High optical clarity diamond plates grown by the CVD method are now available in diameters that exceed that of the largest natural diamond ever found. Products spanning from diamond coated machine t{sq_bullet}oling to semiconducting diamond-based electronics have been developed using this technology. Recent estimates suggest that the global market for chemical vapor deposited diamond and diamond-like carbon films will reach {dollar_sign}1 billion by 2000.

Feigerle, C.S.; Shaw, R.W.

1996-05-01T23:59:59.000Z

294

Dependence of the surface topology and raman scattering spectra of Ge{sub x}Si{sub 1-x}/Si films on the composition variation over the layer thickness  

SciTech Connect (OSTI)

The surface topology and Raman scattering spectra of Ge{sub x}Si{sub 1-x}/Si(100) films are investigated in dependence of the composition variation over the film thickness. It is shown that the character of the Ge content variation in the Ge{sub x}Si{sub 1-x} alloy at the constant cumulative Ge fraction in the film (x{sub int} = 0.5) affects the surface morphology of the grown Ge{sub x}Si{sub 1-x}/Si layer. The heterostructures were grown by molecular-beam epitaxy.

Lunin, L. S.; Sysoev, I. A. [Russian Academy of Sciences, Southern Scientific Center (Russian Federation); Bavizhev, M. D.; Lapin, V. A., E-mail: viacheslavlapin@yandex.ru [North Caucasus Federal University (Russian Federation); Kuleshov, D. S.; Malyavin, F. F. [South Russian State Technical University (Russian Federation)

2013-05-15T23:59:59.000Z

295

Nanostructure formation during ion assisted growth of GaN by molecular beam epitaxy Bentao Cui and P.I. Cohen  

E-Print Network [OSTI]

Nanostructure formation during ion assisted growth of GaN by molecular beam epitaxy Bentao Cui and P.I. Cohen Department of Electrical and Computer Engineering and Department of Chemical Engineering Prairie, MN 55344 (Dated: March 4, 2005) Ion beam assisted molecular beam epitaxy was used to grow Ga

Cohen, Philip I.

296

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

E-Print Network [OSTI]

quality are not yet available for neutron-scattering studies we performed second-order Raman-scattering results of second-order Raman-scattering experiments on hexagonal and cubic GaN covering the acoustic and the optical overtone spectral region. Based on a comparison of the experimental scattering data

Nabben, Reinhard

297

Growth of Core?Shell Ga?GaN Nanostructures via a Conventional Reflux Method and the Formation of Hollow GaN Spheres  

Science Journals Connector (OSTI)

Gallium nitride (GaN) is an important III?V semiconductor with a wide direct band gap of ?3.4 eV. ... LiHMDS exhibits good solubility in TOA. ... The products were collected by centrifugation twice at 7000 rpm for 2 min in hexane, isopropanol, ethanol, and then deionized water. ...

Tz-Jun Kuo; Chi-Liang Kuo; Chun-Hong Kuo; Michael H. Huang

2009-02-05T23:59:59.000Z

298

The reaction of carbon tetrachloride with gallium arsenide ,,001... L. Li., S, Gan, B.-K. Han, H. Qi, and R. F. Hicksa)  

E-Print Network [OSTI]

The reaction of carbon tetrachloride with gallium arsenide ,,001... L. Li., S, Gan, B.-K. Han, H, California 90095 Received 26 June 1997; accepted for publication 30 December 1997 Carbon tetrachloride of steps during the vapor-phase epitaxial growth of III­V compound semiconductors.3,4 Carbon tetrachloride

Li, Lian

299

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

E-Print Network [OSTI]

]. Silicon carbide has a much better lattice match to GaN (3.4%), and has gained in popularity in recent years as a substrate for both molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy of Ga where a transition between streaky and spotty behavior occurs in the reflection high energy electron

Feenstra, Randall

300

Processing quality of Texas-grown pinto beans  

E-Print Network [OSTI]

, and of mild, distinguishable flavor, The Texas-grown cultivars received the highest sensory ratings, with the El Paso 114 receiving the highest overall total score, Idaho 111 received the lowest total score. ACKNOWLEDGEHENTS The author wishes to express...'I of cooked pinto beans. Page 19 21 23 26 28 32 32 34 35 Figure 1 4 5 LIST OF FIGURES Different bean varieties . Typical pinto culti vers Test cultivars of raw pinto beans grown at Thrall, El Paso county, and Idaho Visual examination...

Quenzer, Nancy Marie

2012-06-07T23:59:59.000Z

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

Formation of calcium carbonate films on chitosan substrates in the presence of polyacrylic acid  

SciTech Connect (OSTI)

In this investigation, chitosan membranes with different surface average degrees of deacetylation (DA) are prepared and then are employed as the support matrix to culture calcium carbonate (CaCO{sub 3}). In the presence of high concentration of polyacrylic acid (PAA), the CaCO{sub 3} films obtained on the surface of all chitosan films mainly consisted of vaterite, which suggests the presence of bulk PAA plays an overwhelming part in stabilizing the vaterite. As a comparison, the influences of active groups indicate that only in case of low concentration PAA the thin CaCO{sub 3} films grown on chitosan with 8% DA mainly consisted of vaterite owing to the strong nucleation ability of -NH{sub 2} group, whereas, for those grown on chitosan with 80% DA the CaCO{sub 3} films mainly consisted of aragonite. A more complex scenario revealed that in the case of intermediate concentration of PAA the formed polymorphs behave as mixtures of vaterite and aragonite. - Graphical abstract: Chitosan membranes with different degrees of deacetylation (DA) are employed as support to culture calcium carbonate (CaCO{sub 3}). In high concentration of polyacrylic acid (PAA), the CaCO{sub 3} films obtained consisted of vaterite. However, the CaCO{sub 3} film grown on chitosan with 8% DA mainly consisted of vaterite as opposed to aragonite for chitosan with 8% DA. The schematic presentation of the formation of calcium carbonate on chitosan films with different degrees of acetylation in the presence of PAA with low-, mid- and high concentrations.

He, Linghao; Xue, Rui [Zhengzhou University of Light Industry Henan Provincial Key Laboratory of Surface and Interface Science, Henan, Zhengzhou 450002 (China); Song, Rui, E-mail: rsong@gucas.ac.c [Zhengzhou University of Light Industry Henan Provincial Key Laboratory of Surface and Interface Science, Henan, Zhengzhou 450002 (China); College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China)

2009-05-15T23:59:59.000Z

302

Response of the electric resistance of 40-nm-thick La0.67Ca0.33MnO3 films to an increase in the lattice mismatch between film and substrate  

Science Journals Connector (OSTI)

We have studied the structure and resistivity of 40-nm-thick La0.67Ca0.33MnO3 (LCMO) films coherently grown on (001)-oriented La0.29Sr0.71Al0.65Ta0.35O3 single crystal substrates bearing epitaxial interlayers of ...

Yu. A. Boikov; V. A. Danilov

2005-01-01T23:59:59.000Z

303

Film audio pace  

Science Journals Connector (OSTI)

We explore the concept of film pace expressed through audio to analyse the film at a semantic level. We use domain knowledge to derive a number of measures for film audio pace. We then apply the audio pace to examine two semantic concepts: counterpoint and narrative structure. Counterpoint is a method used to highlight a salient event by contrasting the visual and audio aspects of a film. We divide narrative structure into visual narration, action, and audio narration, plot development. We hypothesise that changes in the narrative structure signal a change in the audio pace. We then test this hypothesis using eight films of varying genres. A pattern was established linking the audio pace features, guided by the properties of the audio energy, to the narrative structure. The method was successful in determining the narrative structure for seven of the films, achieving an overall precision of 76.4% and recall of 80.3%.

Simon Moncrieff; Svetha Venkatesh

2007-01-01T23:59:59.000Z

304

TOWARDS CIGS SOLAR CELLS WITH REDUCED FILM THICKNESS: A STUDY OF OPTICAL PROPERTIES AND OF PHOTONIC STRUCTURES FOR LIGHT TRAPPING  

E-Print Network [OSTI]

TOWARDS CIGS SOLAR CELLS WITH REDUCED FILM THICKNESS: A STUDY OF OPTICAL PROPERTIES AND OF PHOTONIC ABSTRACT: In view of large-scale exploitation of CuIn1-xGaxSe2 (CIGS) solar cells for photovoltaic energy. In this work we perform a full study of optical properties of CIGS solar cells grown by a hybrid sputtering

305

Oxygen-assisted room-temperature deposition of CoPt3 films with perpendicular magnetic anisotropy  

E-Print Network [OSTI]

Oxygen-assisted room-temperature deposition of CoPt3 films with perpendicular magnetic anisotropy B Jolla, California 92093 Received 23 July 2002; accepted 30 September 2002 Trace amounts of oxygen CoPt3 grown by vapor deposition at or slightly above room temperature. Oxygen is known to act

Hellman, Frances

306

Investigation of deep level defects in CdTe thin films  

SciTech Connect (OSTI)

In the past few years, a large body of work has been dedicated to CdTe thin film semiconductors, as the electronic and optical properties of CdTe nanostructures make them desirable for photovoltaic applications. The performance of semiconductor devices is greatly influenced by the deep levels. Knowledge of parameters of deep levels present in as-grown materials and the identification of their origin is the key factor in the development of photovoltaic device performance. Photo Induced Current Transient Spectroscopy technique (PICTS) has proven to be a very powerful method for the study of deep levels enabling us to identify the type of traps, their activation energy and apparent capture cross section. In the present work, we report the effect of growth parameters and LASER irradiation intensity on the photo-electric and transport properties of CdTe thin films prepared by Close-Space Sublimation method using SiC electrical heating element. CdTe thin films were grown at three different source temperatures (630, 650 and 700 °C). The grown films were irradiated with Nd:YAG LASER and characterized by Photo-Induced Current Transient Spectroscopy, Photocurrent measurementand Current Voltage measurements. The defect levels are found to be significantly influenced by the growth temperature.

Shankar, H.; Castaldini, A. [Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Dieguez, E.; Rubio, S. [Crystal Growth Lab, Department of Materials Physics, Faculty of Science, University Autonoma of Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid (Spain); Dauksta, E.; Medvid, A. [Institute of Technical Physics, Riga Technical University, 14 Azenes Str, Riga, Latvia, Department of Materials (Latvia); Cavallini, A. [Department of Physics and Astronomy,University of Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy)

2014-02-21T23:59:59.000Z

307

ThinFilms  

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

308

Nitrogen use in switchgrass grown for bioenergy across the USA  

E-Print Network [OSTI]

Nitrogen use in switchgrass grown for bioenergy across the USA V.N. Owens a , D.R. Viands b , H Available online 17 August 2013 Keywords: Nitrogen removal Switchgrass Bioenergy Nitrogen use efficiency as a forage, conservation, and bioenergy crop [1e5]. It offers a number of distinct benefits including broad

Pawlowski, Wojtek

309

CVD CNT CNT (Vapor-grown carbon fiber, VGCF)  

E-Print Network [OSTI]

CNT CNT CVD CNT CNT (Vapor-grown carbon fiber, VGCF) 10001300 CNT CVD Smalley CO 24 CCVD 1 #12; 27 mm 3% 200 sccm 800 10 10 Torr 300 sccm Ethanol tank Hot bath boat Ar/H2 Ar or Ethanol tank Hot bath Ethanol tank Hot bath Pressure gauge Maindraintube Subdraintube

Maruyama, Shigeo

310

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

SciTech Connect (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

311

Ambient condition laser writing of graphene structures on polycrystalline SiC thin film deposited on Si wafer  

SciTech Connect (OSTI)

We report laser induced local conversion of polycrystalline SiC thin-films grown on Si wafers into multi-layer graphene, a process compatible with the Si based microelectronic technologies. The conversion can be achieved using a 532 nm CW laser with as little as 10 mW power, yielding {approx}1 {mu}m graphene discs without any mask. The conversion conditions are found to vary with the crystallinity of the film. More interestingly, the internal structure of the graphene disc, probed by Raman imaging, can be tuned with varying the film and illumination parameters, resembling either the fundamental or doughnut mode of a laser beam.

Yue, Naili; Zhang, Yong; Tsu, Raphael [Department of Electrical and Computer Engineering and The Center for Optoelectronics and Optical Communications, The University of North Carolina at Charlotte, Charlotte, North Carolina 28223 (United States)] [Department of Electrical and Computer Engineering and The Center for Optoelectronics and Optical Communications, The University of North Carolina at Charlotte, Charlotte, North Carolina 28223 (United States)

2013-02-18T23:59:59.000Z

312

A comparison of ZnO films deposited on indium tin oxide and soda lime glass under identical conditions  

SciTech Connect (OSTI)

ZnO films have been grown via a vapour phase transport (VPT) on soda lime glass (SLG) and indium-tin oxide (ITO) coated glass. ZnO film on ITO had traces of Zn and C which gives them a dark appearance while that appears yellowish-white on SLG. X-ray photoelectron spectroscopy studies confirm the traces of C in the form of C-O. The photoluminescence studies reveal a prominent green luminescence band for ZnO film on ITO.

Deka, Angshuman; Nanda, Karuna Kar [Materials Research Centre, Indian Institute of Science, Bangalore - 560012 (India)

2013-06-15T23:59:59.000Z

313

spe438-20 page 1 Garrison, N.J., Busby, C.J., Gans, P.B., Putirka, K., and Wagner, D.L., 2008, A mantle plume beneath California? The mid-Miocene Lovejoy flood basalt, northern  

E-Print Network [OSTI]

-Miocene Lovejoy flood basalt, northern California Noah J. Garrison Cathy J. Busby Phillip B. Gans Department the eastern Snake River Plain toward the Yellowstone caldera (Armstrong et al., 1975; Rodgers et al., 1990

Busby, Cathy

314

Structure and dielectric properties of La{sub x}Hf{sub (1?x)}O{sub y} thin films: The dependence of components  

SciTech Connect (OSTI)

Graphical abstract: - Highlights: • La{sub x}Hf{sub (1?x)}O{sub y} thin films were grown by pulse laser deposition method. • The thin film with 10% La/(La + Hf) atom ratio forms a cubic HfO{sub 2} phase. • The amorphous thin films due to more La introduced have almost same local structure. • The main infrared phonon modes move to lower frequency for the amorphous thin films. • The static dielectric constants of the amorphous thin films increase with La content. - Abstract: La{sub x}Hf{sub (1?x)}O{sub y} (x = 0, 0.1, 0.3, 0.5, 0.7, y=2?(1/2)x) thin films were grown by pulsed laser deposition (PLD) method. The component dependence of the structure and vibration properties of these thin films is studied by combining X-ray diffraction, X-ray absorption fine structure (XAFS) and infrared spectroscopy. The thin film with 10% La/(La + Hf) atom ratio forms a cubic HfO{sub 2} phase and it has the largest static dielectric constant. More La atoms introduced cause amorphous phase formed and the static dielectric constants increase with the La content. Although XAFS indicates that these amorphous thin films have almost same local structures, the infrared phonon modes with most contribution to the static dielectric constant move to lower frequency, which results in the component dependence of the dielectric constant.

Qi, Zeming, E-mail: zmqi@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China); Cheng, Xuerui [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou, Henan 450002 (China); Zhang, Guobin [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China); Li, Tingting [Institute of Microelectronics of Chinese Academy of Science, Beijing 100029 (China); Wang, Yuyin; Shao, Tao; Li, Chengxiang; He, Bo [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China)

2013-07-15T23:59:59.000Z

315

Magnetic and chemical nonuniformity in Ga{sub 1-x}Mn{sub x}As films as probed by polarized neutron and x-ray reflectometry  

SciTech Connect (OSTI)

We have used complementary neutron and x-ray reflectivity techniques to examine the depth profiles of a series of as-grown and annealed Ga{sub 1-x}Mn{sub x}As thin films. A magnetization gradient is observed for two as-grown films and originates from a nonuniformity of Mn at interstitial sites, and not from local variations in Mn at Ga sites. Furthermore, we see that the depth-dependent magnetization can vary drastically among as-grown Ga{sub 1-x}Mn{sub x}As films despite being deposited under seemingly similar conditions. These results imply that the depth profile of interstitial Mn is dependent not only on annealing, but is also extremely sensitive to initial growth conditions. We observe that annealing improves the magnetization by producing a surface layer that is rich in Mn and O, indicating that the interstitial Mn migrates to the surface. Finally, we expand upon our previous neutron reflectivity study of Ga{sub 1-x}Mn{sub x}As, by showing how the depth profile of the chemical composition at the surface and through the film thickness is directly responsible for the complex magnetization profiles observed in both as-grown and annealed films.

Kirby, B. J.; Borchers, J. A.; Rhyne, J. J.; O'Donovan, K. V.; Velthuis, S. G. E. te; Roy, S.; Sanchez-Hanke, Cecilia; Wojtowicz, T.; Liu, X.; Lim, W. L.; Dobrowolska, M.; Furdyna, J. K. [Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States) and Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States) and Department of Physiology and Biophysics, University of California, Irvine, California 92697 (United States); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States) and Institute of Physics of the Polish Academy of Sciences, 02-688 Warsaw (Poland); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2006-12-15T23:59:59.000Z

316

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

317

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

318

Thick film hydrogen sensor  

DOE Patents [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. 8 figs.

Hoffheins, B.S.; Lauf, R.J.

1995-09-19T23:59:59.000Z

319

Biaxially aligned template films fabricated by inclined-substrate deposition for YBCO-coated conductor applications.  

SciTech Connect (OSTI)

Inclined substrate deposition (ISD) has the potential for rapid production of high-quality biaxially textured buffer layers, which are important for YBCO-coated conductor applications. We have grown biaxially textured MgO films by ISD at deposition rates of 20-100 {angstrom}/sec. Columnar grains with a roof-tile surface structure were observed in the ISD-MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD-MgO films are tilted at an angle from the substrate normal. A small {phi}-scan full-width at half maximum (FWHM) of {approx}9{sup o} was observed on MgO films deposited at an inclination angle of 55{sup o}. In-plane texture in the ISD MgO films developed in the first 0.5 {micro}m from the interface, then stabilized with further increases in film thickness. YBCO films deposited by pulsed laser deposition on ISD-MgO buffered Hastelloy C276 substrates were biaxially aligned with the c-axis parallel to the substrate normal. T{sub c} of 91 K with a sharp transition and transport J{sub c} of 5.5 x 10{sup 5} A/cm{sup 2} at 77 K in self-field were measured on a YBCO film that was 0.46-{micro}m thick, 4-mm wide, 10-mm long.

Ma, B.; Li, M.; Koritala, R. E.; Fisher, B. L.; Erck, R. A.; Dorris, S. E.; Miller, D. J.; Balachandran, U.

2002-08-12T23:59:59.000Z

320

Sharp semiconductor-to-metal transition of VO{sub 2} thin films on glass substrates  

SciTech Connect (OSTI)

Outstanding phase transition properties of vanadium dioxide (VO{sub 2}) thin films on amorphous glass were achieved and compared with the ones grown on c-cut sapphire and Si (111) substrates, all by pulsed laser deposition. The films on glass substrate exhibit a sharp semiconductor-to-metal transition (?4.3?°C) at a near bulk transition temperature of ?68.4?°C with an electrical resistance change as high as 3.2?×?10{sup 3} times. The excellent phase transition properties of the films on glass substrate are correlated with the large grain size and low defects density achieved. The phase transition properties of VO{sub 2} films on c-cut sapphire and Si (111) substrates were found to be limited by the high defect density.

Jian, Jie; Chen, Aiping [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States); Zhang, Wenrui [Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States); Wang, Haiyan, E-mail: wangh@ece.tamu.edu [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843-3128 (United States); Material Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3128 (United States)

2013-12-28T23:59:59.000Z

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

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

SciTech Connect (OSTI)

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

322

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

SciTech Connect (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

323

Interface structure and thermal stability of epitaxial SrTiO{sub 3} thin films on Si (001)  

SciTech Connect (OSTI)

We have used medium energy ion scattering, temperature programmed desorption, and atomic force microscopy to study the interface composition and thermal stability of epitaxial strontium titanate thin films grown by molecular-beam epitaxy on Si (001). The composition of the interface between the film and the substrate was found to be very sensitive to the recrystallization temperature used during growth, varying from a strontium silicate phase when the recrystallization temperature is low to a Ti-rich phase for a higher recrystallization temperature. The films are stable towards annealing in vacuum up to {approx}550 deg.C, where SrO desorption begins and the initially flat film starts to roughen. Significant film disintegration occurs at 850 deg.C, and is accompanied by SiO and SrO desorption, pinhole formation, and finally titanium diffusion into the silicon bulk.

Goncharova, L. V.; Starodub, D. G.; Garfunkel, E.; Gustafsson, T.; Vaithyanathan, V.; Lettieri, J.; Schlom, D. G. [Department of Physics and Astronomy, and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Chemistry and Chemical Biology, and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Physics and Astronomy, and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Material Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2006-07-01T23:59:59.000Z

324

Metal-insulator transition and electrically driven memristive characteristics of SmNiO{sub 3} thin films  

SciTech Connect (OSTI)

The correlated oxide SmNiO{sub 3} (SNO) exhibits an insulator to metal transition (MIT) at 130 deg. C in bulk form. We report on synthesis and electron transport in SNO films deposited on LaAlO{sub 3} (LAO) and Si single crystals. X-ray diffraction studies show that compressively strained single-phase SNO grows epitaxially on LAO while on Si, mixed oxide phases are observed. MIT is observed in resistance-temperature measurements in films grown on both substrates, with charge transport in-plane for LAO/SNO films and out-of-plane for Si/SNO films. Electrically driven memristive behavior is realized in LAO/SNO films, suggesting that SNO may be relevant for neuromorphic devices.

Ha, Sieu D.; Aydogdu, Gulgun H.; Ramanathan, Shriram [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachussets 02138 (United States)

2011-01-03T23:59:59.000Z

325

Diamond and diamond-like carbon films for advanced electronic applications  

SciTech Connect (OSTI)

Aim of this laboratory-directed research and development (LDRD) project was to develop diamond and/or diamond-like carbon (DLC) films for electronic applications. Quality of diamond and DLC films grown by chemical vapor deposition (CVD) is not adequate for electronic applications. Nucleation of diamond grains during growth typically results in coarse films that must be very thick in order to be physically continuous. DLC films grown by CVD are heavily hydrogenated and are stable to temperatures {le} 400{degrees}C. However, diamond and DLC`s exceptional electronic properties make them candidates for integration into a variety of microelectronic structures. This work studied new techniques for the growth of both materials. Template layers have been developed for the growth of CVD diamond films resulting in a significantly higher nucleation density on unscratched or unprepared Si surfaces. Hydrogen-free DLC with temperature stability {le} 800{degrees}C has been developed using energetic growth methods such as high-energy pulsed-laser deposition. Applications with the largest system impact include electron-emitting materials for flat-panel displays, dielectrics for interconnects, diffusion barriers, encapsulants, and nonvolatile memories, and tribological coatings that reduce wear and friction in integrated micro-electro-mechanical devices.

Siegal, M.P.; Friedmann, T.A.; Sullivan, J.P. [and others

1996-03-01T23:59:59.000Z

326

Inclined-substrate deposition of biaxially textured magnesium oxide thin films for YBCO coated conductors.  

SciTech Connect (OSTI)

Highly textured MgO films were grown by the inclined-substrate deposition (ISD) technique at a high deposition rate. A columnar grain with a roofing-tile-shaped surface was observed in these MgO films. X-ray pole figure, and {phi}- and {omega}-scan were used to characterize in-plane and out-of-plane textures. MgO films deposited when the incline angle {alpha} was 55 and 30 degrees exhibited the best in-plane and out-of-plane texture, respectively. High-quality YBCO films were epitaxially grown on ISD-MgO-buffered Hastelloy C substrates by pulsed laser deposition. {Tc}=88 K, with sharp transition, and j{sub c} values of {approx}2x10{sup 5} A/cm{sup 2} at 77 K in zero field were observed on films 5 mm wide and 1 cm long. This work has demonstrated that biaxially textured ISD MgO buffer layers deposited on metal substrates are excellent candidates for fabrication of high-quality YBCO coated conductors.

Ma, B.; Li, M.; Jee, Y. A.; Koritala, R. E.; Fisher, B. L.; Balachandran, U.; Energy Technology

2002-02-01T23:59:59.000Z

327

LiMnPO4 Nanoplate Grown via Solid-State Reaction in Molten Hydrocarbon...  

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

LiMnPO4 Nanoplate Grown via Solid-State Reaction in Molten Hydrocarbon for Li-ion Battery Cathode. LiMnPO4 Nanoplate Grown via Solid-State Reaction in Molten Hydrocarbon for Li-ion...

328

Modeling of film growth by cluster deposition: The effect of size and energy  

Science Journals Connector (OSTI)

The density of cluster-assembled thin films depends heavily on the size of the deposited clusters as well as the energy with which they impact the substrate. Using molecular-dynamics simulations we have quantitatively studied variations in the density of thin films grown by deposition of clusters, with diameters between 1 and 9 nm, and at energies ranging from 2 meV to 10 eV per cluster atom. A model explaining the behavior of smaller clusters is presented, and a threshold limit in cluster size, where deviation from this model occurs, is determined. The deviation is shown to be due to a lessened sintering between clusters.

K. Meinander and K. Nordlund

2009-06-26T23:59:59.000Z

329

99.996 %{sup 12}C films isotopically enriched and deposited in situ  

SciTech Connect (OSTI)

Ionizing natural abundance carbon dioxide gas, we extract and mass select the ions, depositing thin films isotopically enriched to 99.9961(4) %{sup 12}C as measured by secondary ion mass spectrometry (SIMS). In solid state quantum information, coherence times of nitrogen-vacancy (NV) centers in {sup 12}C enriched diamond exceeding milliseconds demonstrate the viability of NV centers as qubits, motivating improved isotopic enrichment. NV centers in diamond are particularly attractive qubit candidates due to the optical accessibility of the spin states. We present SIMS analysis and cross-sectional scanning electron microscopy of {sup 12}C enriched thin film samples grown with this method.

Dwyer, K. J. [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20740 (United States) [Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20740 (United States); National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8423 (United States); Pomeroy, J. M.; Simons, D. S. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8423 (United States)] [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8423 (United States)

2013-06-24T23:59:59.000Z

330

MICROSTRUCTURE STUDY ON THE La0.7Sr0.3MnO3 AND RARE-EARTH OXIDE VERTICALLY ALIGNED NANOCOMPOSITE THIN FILMS  

E-Print Network [OSTI]

NANOCOMPOSITE THIN FILMS Approved by: Research Advisor: Haiyan Wang Director for Undergraduate Research... A&M University Research Advisor: Dr. Haiyan Wang Department of Electrical and Electrical Engineering Two-phase (La0.7Sr0.3MnO3)0.5:(CeO2)0.5 (LSMO:CeO2) heteroepitaxial nanocomposite films were grown on SrTiO3 (STO) (001) by pulsed laser...

Hazariwala, Harshad

2011-05-05T23:59:59.000Z

331

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

332

Fungicidal control of Phthium Aphanidermatum in hydroponically grown tomatoes  

E-Print Network [OSTI]

FUNGICIDAL CONTROL OF PYTHIUM APHANIDERMATUM IN HYDROPONICALLY GROMN TOMATOES A Thesis by MICHEL AFTIM ACRA Submitted to the Graduate College of Texas AILM University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE December 1979 Major Subject: Horticulture FUNGICIDAL CONTROL OF PYTHIUM APHANIDERMATUM IN HYDROPONICALLY GROWN TOMATOES A Thesis by MICHEL AFTIM ACRA Approved as to style and content by: (Co~as n of Com ' pe (Co-Chairman of~ ommittee...

Acra, Michel Aftim

2012-06-07T23:59:59.000Z

333

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

334

A water film motor  

E-Print Network [OSTI]

We report on electrically-induced rotations in water films, which can function at many length scales. The device consists of a two-dimensional cell used for electrolysis of water films, as simple as an insulator frame with two electrodes on the sides, to which an external in-plane electric field perpendicular to the mean electrolysis current density is applied. If either the external field or the electrolysis current exceeds some threshold (while the other one is not zero), the liquid film begins to rotate.

R. Shirsavar; A. Amjadi; N. Hamedani Radja; M. D. Niry; M. Reza Rahimi Tabar; M. R. Ejtehadi

2006-05-01T23:59:59.000Z

335

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. 5 figs.

Cheng, Y.T.; Poli, A.A.; Meltser, M.A.

1999-03-23T23:59:59.000Z

336

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

337

Photonic Crystal Cavities in Cubic (3C) Polytype Silicon Carbide Films  

E-Print Network [OSTI]

We present the design, fabrication, and characterization of high quality factor and small mode volume planar photonic crystal cavities from cubic (3C) thin films (thickness ~ 200 nm) of silicon carbide (SiC) grown epitaxially on a silicon substrate. We demonstrate cavity resonances across the telecommunications band, with wavelengths from 1,250 - 1,600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

Marina Radulaski; Thomas M. Babinec; Sonia Buckley; Armand Rundquist; J Provine; Kassem Alassaad; Gabriel Ferro; Jelena Vu?kovi?

2013-11-30T23:59:59.000Z

338

Characterization of few-layered graphene grown by carbon implantation  

SciTech Connect (OSTI)

Graphene is considered to be a very promising material for applications in nanotechnology. The properties of graphene are strongly dependent on defects that occur during growth and processing. These defects can be either detrimental or beneficial to device performance depending on defect type, location and device application. Here we present experimental results on formation of few-layered graphene by carbon ion implantation into nickel films and characteristics of graphene devices formed by graphene transfer and lithographic patterning. Micro-Raman spectroscopy was used to determine the number of graphene layers formed and identify defects arising from the device processing. The graphene films were cleaned by annealing in vacuum. Transport properties of cleaned graphene films were investigated by fabrication of back-gated field-effect transistors, which exhibited high hole and electron mobility of 1935 and 1905 cm2/Vs, respectively.

Lee, Kin Kiong; McCallum, Jeffrey C.; Jamieson, David N. [Centre for Quantum Computation and Communication Technology, School of Physics, The University of Melbourne, Parkville, Victoria 3010 (Australia)

2014-02-21T23:59:59.000Z

339

On the influence of solution density on the formation of macroscopic defects in the liquid phase epitaxy of GaN  

Science Journals Connector (OSTI)

This paper reports on a new simple method for avoiding particle-induced macroscopic defects using the liquid phase epitaxy (LPE) of GaN as an example. In a series of growth experiments by LPE of GaN it is demonstrated that the number of particle-induced macrodefects in the epitaxial layers correlates strongly and reproducibly with the density of the solution. In solutions with a density higher than that of the deleterious particles, the particles float on the solution and hence are hindered to get into contact with the seed, which is placed at the bottom of the crucible. Consequently, so-called depressions — a typical particle-induced defect in GaN–LPE layers — are avoided. The principle of avoiding the formation of macroscopic defects originating from particles by adapting the density of the solution (density criterion) should be generally applicable to solution growth processes, regardless of the material system.

S. Hussy; P. Berwian; E. Meissner; J. Friedrich; G. Müller

2008-01-01T23:59:59.000Z

340

Confirmation of intrinsic electron gap states at nonpolar GaN(1-100) surfaces combining photoelectron and surface optical spectroscopy  

SciTech Connect (OSTI)

The electronic structure of GaN(1–100) surfaces is investigated in-situ by photoelectron spectroscopy (PES) and reflection anisotropy spectroscopy (RAS). Occupied surface states 3.1?eV below the Fermi energy are observed by PES, accompanied by surface optical transitions found in RAS around 3.3?eV, i.e., below the bulk band gap. These results indicate that the GaN(1–100) surface band gap is smaller than the bulk one due to the existence of intra-gap states, in agreement with density functional theory calculations. Furthermore, the experiments demonstrate that RAS can be applied for optical surface studies of anisotropic crystals.

Himmerlich, M., E-mail: marcel.himmerlich@tu-ilmenau.de; Eisenhardt, A.; Shokhovets, S.; Krischok, S. [Institut für Physik and Institut für Mikro- und Nanotechnologien, TU Ilmenau, PF 100565, 98684 Ilmenau (Germany); Räthel, J.; Speiser, E.; Neumann, M. D.; Navarro-Quezada, A.; Esser, N. [Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Albert-Einstein-Strasse 9, 12489 Berlin (Germany)

2014-04-28T23:59:59.000Z

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

E. P. R. CHARACTERIZATION OF p-TYPE AS GROWN AND Cl-COMPENSATED THM GROWN CdTe  

E-Print Network [OSTI]

band gaps (ZnS, CdS) [1], only scarce observations on lower band-gap materials have been reported is observed in as-grown CdTe, and, even without illumination, a signal at g = 2.003 ± 0.001 appears in heavily-doped. For CdTe, only extrinsic centers induced by doping with transition metal or rare earth ions have been

Boyer, Edmond

342

Thin Film Photovoltaics Research  

Broader source: Energy.gov [DOE]

The U.S. Department of Energy (DOE) supports research and development of four thin-film technologies on the path to achieving cost-competitive solar energy, including:

343

Amorphous diamond films  

DOE Patents [OSTI]

Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

Falabella, S.

1998-06-09T23:59:59.000Z

344

Growth of Fe3N films via chemical vapor deposition of iron acetylacetonate and anhydrous ammonia  

Science Journals Connector (OSTI)

Polycrystalline Fe3N films have been grown via chemical vapor deposition (CVD) on 50-?m thick polycrystalline Ti substrates using iron acetylacetonate (IAA) and anhydrous ammonia (NH3) in a cold-wall vertical pancake-style reactor. X-ray diffraction data indicated that single phase Fe3N was present in films deposited at and above 600°C; below this temperature no deposition occurred. The composition of the Fe3N films did not vary with changes in the deposition temperature, the NH3 flow rate or the deposition rate at a constant deposition pressure of 100 Torr. The surface macrostructure of the as-deposited films was independent of the deposition temperature and was very similar to that of the uncoated Ti substrate. The microstructure of the films was porous with a thickness variation of ?1 ?m across the surface of the films. Larger grains were produced at 600 and 800°C, while smaller and more uniform grains were produced at 700°C. Energy dispersive X-ray data indicated that films deposited at and above 600°C contained low levels of both carbon and oxygen.

S.L. Roberson; D. Finello; A.D. Banks; R.F. Davis

1998-01-01T23:59:59.000Z

345

Fe thin-film growth on Au(100): A self-surfactant effect and its limitations  

Science Journals Connector (OSTI)

The combination of low-energy electron diffraction intensity analyses and scanning tunneling microscopy was used to investigate the morphology and atomic structure of thin Fe films grown on Au(100) at 400 K. Deposition of only about 0.2 monolayers (ML) Fe is sufficient to lift the reconstruction of the clean substrate. In the initial growth process (<~1 ML) place exchanges between Fe and Au lead to almost two-dimensional subsurface Fe film growth with one layer of Au covering the entire film. This way, gold acts as a “self-surfactant.” Yet, there are deviations from two-dimensional growth, with a second Fe layer beginning to grow before the first one is fully completed and some substitutional disorder developing in the film because of incomplete place exchange. The amount of gold floating on the surface only gradually decreases with further increasing film thickness. At about 2 ML the surface undergoes a complete restructuring during which short “wormlike” chains of atoms form and long-range order is destroyed. Nevertheless, the existence of large terraces of little roughness proves that some surface activity of gold remains. At coverages of several ML, long-range order is reestablished with the Fe film growing in an undistorted bcc arrangement. Although parts of the film are still covered by gold, the surface morphology is not very different from that known for homoepitaxial growth of Fe on Fe(100), i.e., gold has stopped to serve as a “self-surfactant.”

V. Blum, Ch. Rath, S. Müller, L. Hammer, K. Heinz, J. M. García, J. E. Ortega, J. E. Prieto, O. S. Hernán, J. M. Gallego, A. L. Vázquez de Parga, and R. Miranda

1999-06-15T23:59:59.000Z

346

Magnetization of uncovered and V-covered ultrathin Fe(100) films on V(100)  

SciTech Connect (OSTI)

We used polarized neutron reflectometry (PNR) to determine the absolute magnetic moment of uncovered and V-covered Fe films in the thickness range from 0.3 to 5.5 nm. The films were prepared by molecular beam epitaxy on a V(100) buffer layer grown on a MgO(100) crystal. The magnetic moment shows a linear dependence on the Fe film thickness with a reduction (compared to the Fe bulk value) of the magnetic moment equivalent to 0.1 nm bulk Fe for the V-covered films and a reduction equivalent to 0.03 nm bulk Fe for the uncovered Fe films. For the case of the V/Fe/V samples we observe a much smaller reduction of the magnetic moment than reported for experiments on Fe/V multilayers. As theoretical calculations show a strong decrease of the magnetic moment for an interface alloy we conclude that the larger reduction of the magnetization in Fe/V multilayers is due to an increase in interface roughness with increasing film thickness. For the uncovered Fe(100) films we find a much smaller reduction of the magnetic moment than in earlier in situ PNR experiments on V(110)/Fe(110) where we observed a reduction equivalent to 0.4 nm bulk Fe.

Fritzsche, H.; Liu, Y.T.; Hauschild, J.; Maletta, H. [National Research Council Canada, SIMS, NPMR, Chalk River Labs, Bldg. 459, Chalk River, ON, K0J 1J0 (Canada); Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

2004-12-01T23:59:59.000Z

347

Sputtering of Si, SiC, InAs, InP, Ge, GaAs, GaSb, and GaN by electrosprayed nanodroplets  

SciTech Connect (OSTI)

This article presents a characterization of the damage caused by energetic beams of electrosprayed nanodroplets striking the surfaces of single-crystal semiconductors including Si, SiC, InAs, InP, Ge, GaAs, GaSb, and GaN. The sputtering yield (number of atoms ejected per projectile's molecule), sputtering rate, and surface roughness are measured as functions of the beam acceleration potential. The maximum values of the sputtering yields range between 1.9 and 2.2 for the technological important but difficult to etch SiC and GaN respectively, and 4.5 for Ge. The maximum sputtering rates for the non-optimized beam flux conditions used in our experiments vary between 409?nm/min for SiC and 2381?nm/min for GaSb. The maximum sputtering rate for GaN is 630?nm/min. Surface roughness increases modestly with acceleration voltage, staying within 2?nm and 20?nm for all beamlet acceleration potentials and materials except Si. At intermediate acceleration potentials, the surface of Si is formed by craters orders of magnitude larger than the projectiles, yielding surface roughness in excess of 60?nm. The effect of projectile dose is studied in the case of Si. This parameter is correlated with the formation of the large craters typical of Si, which suggests that the accumulation of damage following consecutive impacts plays an important role in the interaction between beamlet and target.

Borrajo-Pelaez, Rafael; Grustan-Gutierrez, Enric; Gamero-Castaño, Manuel, E-mail: mgameroc@uci.edu [Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92697 (United States)

2013-11-14T23:59:59.000Z

348

JOURNAL DE PHYSIQUE Colloque C6, supplment au n" 8, Tome 39, aot 1978, page C6-448 INCREASED RESISTANCE BELOW THE SUPERCONDUCTING TRANSITION IN DISCONTINUOUS FILMS  

E-Print Network [OSTI]

substrates using the original technique III. Transmission electron micrographs of ultra thin films grown mK. To counter the high sample resistances which occur at low temperatures gold electrodes of favourable aspect ratio. Measure- ments on 25 samples in the range 20 K to 400 mK (fig. 2) all show

Boyer, Edmond

349

Electric resistance of La0.67Ca0.33MnO3 films biaxially strained during growth on lattice-mismatched substrates  

Science Journals Connector (OSTI)

We have studied the electric resistance of 20-nm-thick La0.67Ca0.33MnO3 films coherently grown on single crystal substrates with considerable (negative) and almost zero lattice mismatch. The unit cell volume in t...

Yu. A. Boikov; V. A. Danilov

2004-07-01T23:59:59.000Z

350

Electric resistance and magnetoresistance of 30-nm-Thick La0.67Ca0.33MnO3 films elastically compressed in the (110) plane  

Science Journals Connector (OSTI)

We have studied the structure, electric resistance, and magnetoresistance of 30-nm-thick (...0.67Ca0.33MnO3 (LCMO) films grown by laser deposition on (001)-oriented LaAlO3 substrates. The unit cell parameters a a...

Yu. A. Boikov; M. P. Volkov

2008-11-01T23:59:59.000Z

351

Nanotransfer 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. A method includes depositing a catalyst particle on a surface of a substrate to define a deterministically located position; growing an aligned elongated nanostructure on the substrate, an end of the aligned elongated nanostructure coupled to the substrate at the deterministically located position; coating the aligned elongated nanostructure with a conduit material; removing a portion of the conduit material to expose the catalyst particle; removing the catalyst particle; and removing the elongated nanostructure to define a nanoconduit.

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

2011-05-17T23:59:59.000Z

352

Unusual thermopower of inhomogeneous graphene grown by chemical vapor deposition  

SciTech Connect (OSTI)

We report on thermopower (TEP) and resistance measurements of inhomogeneous graphene grown by chemical vapor deposition (CVD). Unlike the conventional resistance of pristine graphene, the gate-dependent TEP shows a large electron-hole asymmetry. This can be accounted for by inhomogeneity of the CVD-graphene where individual graphene regions contribute with different TEPs. At the high magnetic field and low temperature, the TEP has large fluctuations near the Dirac point associated with the disorder in the CVD-graphene. TEP measurements reveal additional characteristics of CVD-graphene, which are difficult to obtain from the measurement of resistance alone.

Nam, Youngwoo, E-mail: youngwoo.nam@chalmers.se [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Sun, Jie; Lindvall, Niclas; Yurgens, August [Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Jae Yang, Seung; Rae Park, Chong [Department of Materials Science and Engineering, Seoul National University, Seoul 151-747 (Korea, Republic of); Woo Park, Yung [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

2014-01-13T23:59:59.000Z

353

Top-gate thin-film transistors based on GaN channel layer Rongsheng Chen, Wei Zhou, and Hoi Sing Kwok  

E-Print Network [OSTI]

exhibit good electrical performance such as field effect mobility of 1 cm2 /Vs, threshold voltage of �0 and poly-Si TFTs.6­8 However, the poor electrical sta- bility of ZnO-based TFTs is still a main issue mobility (6 � 10�2 cm2 /Vs) and low on/off current ratio (3 � 103 ), due to local- ized gap states in Ga

354

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

E-Print Network [OSTI]

dissipation of 1.8W. Table 1 gives the thermal conductivity of the materials used in the simul grown on SiC or sapphire substrates. Sapphire substrates are relatively cheap, but their low thermal conductivity is a major disadvantage. To improve the thermal performance, a hybrid integration of the HEMT onto

Paris-Sud XI, Université de

355

NMR characterization of thin films  

DOE Patents [OSTI]

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

356

Low-energy muon [LEM] study of Zn-phthalocyanine and ZnO thin films  

Science Journals Connector (OSTI)

Implantation of low-energy muons in zinc-phthalocyanine (ZnPc) thin-films leads to the formation of muoniated radical states, the fast decaying of the ? SR signal at low fields being a clear indication of muonium formation. The formation probability of these paramagnetic states is independent of the implantation depth and amounts, as in the bulk, to approximately 100% of all muons. In these molecular crystals the formation of muonium is a highly local effect and is fairly independent of crystalline structure and defects in the sample. In contrast to that, in vapour-grown ZnO films the paramagnetic signal known from bulk experiments is not observed, even for the deeper implantations. We suggest that in this case muonium is not formed due to the low concentration of free electrons. In these strongly distorted films, electrons are captured at defects and are not available for muonium formation.

H.V. Alberto; J. Piroto Duarte; A. Weidinger; R.C. Vilão; J.M. Gil; N. Ayres de Campos; K. Fostiropoulos; T. Prokscha; A. Suter; E. Morenzoni

2009-01-01T23:59:59.000Z

357

Enhanced ultraviolet photoconductivity in semiconducting ZnGa{sub 2}O{sub 4} thin films  

SciTech Connect (OSTI)

We have investigated the conductivity and photoconductivity response of undoped and Li-doped ZnGa{sub 2}O{sub 4} epitaxial films grown using pulsed-laser deposition. A significant enhancement of the ultraviolet (UV) photoresponse is observed with Li doping that also correlates with an enhanced luminescent intensity. The wavelength dependence observed for creation of free carriers under UV excitation suggests that the transition is either band-to-band or involves a defect level near the band edge. Moderate n-type dark conductivity is observed for undoped films processed under reducing conditions. With Li doping, dark conductivity is reduced, suggesting that lithium ions in the zinc gallate lattice serve as deep acceptors. In addition, Li doping effectively eliminates persistent photoconductivity that is commonly observed in undoped films, suggesting the possible use of Li-doped ZnGa{sub 2}O{sub 4} as a visible wavelength blind UV photodetector.

Lee, Yong Eui; Norton, David P.; Budai, John D.; Wei, Yayi

2001-10-15T23:59:59.000Z

358

Method for continuous control of composition and doping of pulsed laser deposited films  

DOE Patents [OSTI]

A method for growing a deposit upon a substrate of semiconductor material involves the utilization of pulsed laser deposition techniques within a low-pressure gas environment. The substrate and a target of a first material are positioned within a deposition chamber and a low-pressure gas atmosphere is developed within the chamber. The substrate is then heated, and the target is irradiated, so that atoms of the target material are ablated from the remainder of the target, while atoms of the gas simultaneously are adsorbed on the substrate/film surface. The ablated atoms build up upon the substrate, together with the adsorbed gas atoms to form the thin-film deposit on the substrate. By controlling the pressure of the gas of the chamber atmosphere, the composition of the formed deposit can be controlled, and films of continuously variable composition or doping can be grown from a single target of fixed composition.

Lowndes, Douglas H. (Knoxville, TN); McCamy, James W. (Knoxville, TN)

1995-01-01T23:59:59.000Z

359

Method for continuous control of composition and doping of pulsed laser deposited films by pressure control  

DOE Patents [OSTI]

A method for growing a deposit upon a substrate of semiconductor material involves the utilization of pulsed laser deposition techniques within a low-pressure gas environment. The substrate and a target of a first material are positioned within a deposition chamber and a low-pressure gas atmosphere is developed within the chamber. The substrate is then heated, and the target is irradiated, so that atoms of the target material are ablated from the remainder of the target, while atoms of the gas simultaneously are adsorbed on the substrate/film surface. The ablated atoms build up upon the substrate, together with the adsorbed gas atoms to form the thin-film deposit on the substrate. By controlling the pressure of the gas of the chamber atmosphere, the composition of the formed deposit can be controlled, and films of continuously variable composition or doping can be grown from a single target of fixed composition.

Lowndes, Douglas H. (Knoxville, TN); McCamy, James W. (Knoxville, TN)

1996-01-01T23:59:59.000Z

360

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

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

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

362

Effects of defect clustering on optical properties of GaN by single and molecular ion irradiation  

SciTech Connect (OSTI)

The effects of irradiation by F, P, and PF{sub 4} on optical properties of GaN were studied experimentally and by atomistic simulations. Additionally, the effect of Ag was studied by simulation. The irradiation energy was 0.6?keV/amu for all projectiles. The measured photoluminescence (PL) decay time was found to be decreasing faster when irradiation was done by molecular ion compared to light ion irradiation. The PL decay time change is connected with the types of defect produced by different projectiles. Simulation results show that the light ions mainly produce isolated point defects while molecular and heavy ions produce clusters of point defects. The total amount of defects produced by the PF{sub 4} projectile was found to be very close to the sum of all defects produced in five individual cascades started by one P and four F single ions. This and the similar depth profiles of damage produced by molecular and light ion irradiations suggest that the defect clusters are one of the important reasons for fast PL decay. Moreover, the simulations of irradiation by Ag ions, whose mass is close to the mass of the PF{sub 4} molecule, showed that the produced defects are clustering in even bigger conglomerates compared to PF{sub 4} case. The latter has a tendency to split in the pre-surface region, reducing on average the density of the collision cascade.

Ullah, M. W., E-mail: mohammad.ullah@helsinki.fi; Kuronen, A.; Nordlund, K.; Djurabekova, F. [Department of Physics, University of Helsinki, P.O. Box 64, FIN 00014 (Finland); Karaseov, P. A.; Karabeshkin, K. V.; Titov, A. I. [Department of Physical Electronics, St. Petersburg State Polytechnic University, St. Petersburg (Russian Federation)

2013-11-14T23:59:59.000Z

363

Strain modified/enhanced ferromagnetism in Mn{sub 3}Ge{sub 2} thin films on GaAs(001) and GaSb(001)  

SciTech Connect (OSTI)

Ferromagnetic Mn{sub 3}Ge{sub 2} thin films were successfully grown on GaAs(001) and GaSb(001) substrates using molecular beam epitaxy. The results of our work revealed that the substrate facilitates to modify magnetic and electrical properties of Mn{sub 3}Ge{sub 2} films due to tensile/compressive strain effect between films and substrates. The characteristic spin-flopping transition at around 150 K for the bulk Mn{sub 3}Ge{sub 2} disappeared completely for both samples. The antiferromagnetism below 150 K changed to ferromagnetism and retained above room temperature. The saturation magnetization was found to be 0.23 and 1.32 {mu}{sub B}/Mn atom at 10 K for the samples grown on GaSb(001) and GaAs(001), respectively.

Dang Duc Dung; Duong Van Thiet [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); Feng Wuwei; Cho, Sunglae [Department of Physics, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Park, In-Sung [Department of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Bo Lee, Sung [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2013-04-21T23:59:59.000Z

364

Formation of Nickel Silicide from Direct-liquid-injection Chemical-vapor-deposited Nickel Nitride Films  

SciTech Connect (OSTI)

Smooth, continuous, and highly conformal nickel nitride (NiN{sub x}) films were deposited by direct liquid injection (DLI)-chemical vapor deposition (CVD) using a solution of bis(N,N{prime}-di-tert-butylacetamidinato)nickel(II) in tetrahydronaphthalene as the nickel (Ni) source and ammonia (NH{sub 3}) as the coreactant gas. The DLI-CVD NiNx films grown on HF-last (100) silicon and on highly doped polysilicon substrates served as the intermediate for subsequent conversion into nickel silicide (NiSi), which is a key material for source, drain, and gate contacts in microelectronic devices. Rapid thermal annealing in the forming gas of DLI-CVD NiNx films formed continuous NiSi films at temperatures above 400 C. The resistivity of the NiSi films was 15{mu}{Omega} cm, close to the value for bulk crystals. The NiSi films have remarkably smooth and sharp interfaces with underlying Si substrates, thereby producing contacts for transistors with a higher drive current and a lower junction leakage. Resistivity and synchrotron X-ray diffraction in real-time during annealing of NiNx films showed the formation of a NiSi film at about 440 C, which is morphologically stable up to about 650 C. These NiSi films could find applications in future nanoscale complementary metal oxide semiconductor devices or three-dimensional metal-oxide-semiconductor devices such as Fin-type field effect transistors for the 22 nm technology node and beyond.

Li, Z.; Gordon, R; Li, H; Shenai, D; Lavoie, C

2010-01-01T23:59:59.000Z

365

E-Print Network 3.0 - aln thin films Sample Search Results  

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

devices 2. GaN has also a direct energy... in microelectronics and optoelectronics ... Source: Boo, Jin-Hyo - Department of Chemistry, Sungkyunkwan University;...

366

Thermodynamic study of c-axis-oriented epitaxial Pb(Zr,Ti)O3 thin films  

Science Journals Connector (OSTI)

Thermodynamic characteristics of single crystalline Pb(Zr0.52Ti0.48)O3 (PZT) were investigated using c-axis oriented PZT films. The PZT films were epitaxially grown on Pt/MgO substrate and dielectric and ferroelectric properties were measured as a function of one-dimensional stress. The stress dependence of dielectric and ferroelectric properties was examined on the basis of the Landau-Devonshire’s phenomenological theory and the free energy coefficients of single crystalline PZT films were obtained. The dielectric stiffness coefficients and electrostrictive coefficient of epitaxial PZT films were obtained to be ?1=-1.30×108 (m/F), ?11=3.07×108 (m5/C2F), ?111=-3.11×107 (m9/C2F), and Q12=-5.70×10-2 (m4/C2), which are different from the values derived from the analysis of polycrystalline PZT. The temperature dependence of dielectric constant of the PZT films showed clear Curie-Weiss law and the dielectric stiffness coefficient ?1 derived from this measurement was almost same value from the analysis of stress dependence of the dielectricity of the epitaxial PZT films.

Isaku Kanno; Yu Yokoyama; Hidetoshi Kotera; Kiyotaka Wasa

2004-02-12T23:59:59.000Z

367

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

SciTech Connect (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

368

Growth of HfO{sub 2} films using an alternate reaction of HfCl{sub 4} and O{sub 2} under atmospheric pressure  

SciTech Connect (OSTI)

HfO{sub 2} films were deposited onto a Si(100) substrate using an alternate reaction of HfCl{sub 4} and O{sub 2} under atmospheric pressure. Self-limiting growth of the HfO{sub 2} was achieved in the range of the growth temperature above 873K. The X-ray diffraction of the HfO{sub 2} films showed a typical diffraction pattern assigned to the monoclinic polycrystalline phase. Residual chloride concentration in HfO{sub 2} films were not higher than 0.1at%. When the growth temperature was 973K, the HfSiO{sub x} is formed in HfO{sub 2} film. This gives effective permittivity value of 9.6 for the HfO{sub 2} film grown at 573K.

Takahashi, Naoyuki [Department of Materials Science and Technology, Faculty of Engineering Shizuoka University, 3-5-1 Johoku, Hamamatu, Shizuoka 432-8561 (Japan)]. E-mail: tntakah@ipc.shizuoka.ac.jp; Nonobe, Shinichi [Department of Materials Science and Technology, Faculty of Engineering Shizuoka University, 3-5-1 Johoku, Hamamatu, Shizuoka 432-8561 (Japan); Nakamura, Takato [Department of Materials Science and Technology, Faculty of Engineering Shizuoka University, 3-5-1 Johoku, Hamamatu, Shizuoka 432-8561 (Japan)

2004-11-01T23:59:59.000Z

369

Low-temperature oriented growth of vanadium dioxide films on CoCrTa metal template on Si and vertical metal-insulator transition  

SciTech Connect (OSTI)

The authors achieved oriented growth of vanadium dioxide (VO{sub 2}) films on CoCrTa metal template grown on an Si substrate. Low-temperature ({approx}250 Degree-Sign C) deposition of VO{sub 2} films using inductively coupled-plasma-assisted sputtering technique realized an abrupt interface between VO{sub 2} and CoCrTa layers, suppressing the oxidation and diffusion of metal components. The films revealed a metal-insulator transition with resistance change of over 2 orders of magnitude. The CoCrTa film, in which Co hexagonal crystalline grains with c-axis orientation were surrounded by segregated Cr and Ta, serves for the oriented growth of VO{sub 2} crystalline film, enabling higher orders of transition in resistance and low voltage switching, even for the vertical (out-of-plane) direction.

Okimura, Kunio; Mian, Md.Suruz [School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan)

2012-09-15T23:59:59.000Z

370

Thermoelectric properties of lattice-matched AlInN alloy grown by metal organic chemical vapor deposition  

E-Print Network [OSTI]

Seebeck coefficient and resistance measurement system for thermoelectric materials in the thin diskInN alloy on GaN as excellent material candidate for thermoelectric application. © 2010 American Institute-nitride alloys have shown promising results for thermoelectric applications,20­30 in particular for materi- als

Gilchrist, James F.

371

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

SciTech Connect (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

372

Magnetic properties of epitaxial Co-doped anatase TiO2 thin films with excellent structural quality  

SciTech Connect (OSTI)

The heteroepitaxy of Co-doped anatase TiO2 on LaAlO3(001) has been refined with the goal of determining the relationship between structural quality and magnetic ordering. By significantly reducing the deposition rate and substrate temperature, well-ordered Co:TiO2 films with unprecedented crystalline quality were obtained by oxygen-plasma-assisted molecular beam epitaxy, as characterized by x-ray diffraction. These films exhibit uniform Co doping, with no evidence of Co segregation or secondary phases throughout the film depth or on the surface. Despite the improvement in crystalline quality and Co distribution, the films exhibit negligible ferromagnetism, with saturation moments of only ~0.1 ?B/Co. This loss of ferromagnetism is in stark contrast to faster-grown Co:TiO2 films, where a higher growth rate and substrate temperature typically result in lower crystalline quality, a highly non-uniform Co distribution, and average saturation moments of ~1.2 ?B/Co. The presence of ferromagnetism in faster-grown Co:TiO2 does not appear to arise from intrinsic point defects present in the bulk material, such as charge-compensating oxygen vacancies, but is instead attributed to the presence of extended structural defects.

Kaspar, Tiffany C.; Droubay, Timothy C.; McCready, David E.; Nachimuthu, Ponnusamy; Heald, Steve M.; Wang, Chong M.; Lea, Alan S.; Shutthanandan, V.; Chambers, Scott A.; Toney, Michael F.

2006-07-26T23:59:59.000Z

373

Diamond films: Historical perspective  

SciTech Connect (OSTI)

This section is a compilation of notes and published international articles about the development of methods of depositing diamond films. Vapor deposition articles are included from American, Russian, and Japanese publications. The international competition to develop new deposition methodologies is stressed. The current status of chemical vapor deposition of diamond is assessed.

Messier, R. [Pennsylvania State Univ., University Park (United States)

1993-01-01T23:59:59.000Z

374

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

375

Suppression of the thermal hysteresis in magnetocaloric MnAs thin film by highly charged ion bombardment  

E-Print Network [OSTI]

We present the investigation on the modifications of structural and magnetic properties of MnAs thin film epitaxially grown on GaAs induced by slow highly charged ions bombardment under well-controlled conditions. The ion-induced defects facilitate the nucleation of one phase with respect to the other in the first-order magneto-structural MnAs transition with a consequent suppression of thermal hysteresis without any significant perturbation on the other structural and magnetic properties. In particular, the irradiated film keeps the giant magnetocaloric effect at room temperature opening new perspective on magnetic refrigeration technology for everyday use.

Trassinelli, Martino; Eddrief, M; Etgens, V H; Gafton, V; Hidki, S; Lacaze, Emmanuelle; Lamour, Emily; Prigent, Christophe; Rozet, Jean-Pierre; Steydli, S; Zheng, Y; Vernhet, Dominique

2014-01-01T23:59:59.000Z

376

Suppression of the thermal hysteresis in magnetocaloric MnAs thin film by highly charged ion bombardment  

SciTech Connect (OSTI)

We present the investigation on the modifications of structural and magnetic properties of MnAs thin film epitaxially grown on GaAs induced by slow highly charged ions bombardment under well-controlled conditions. The ion-induced defects facilitate the nucleation of one phase with respect to the other in the first-order magneto-structural MnAs transition, with a consequent suppression of thermal hysteresis without any significant perturbation on the other structural and magnetic properties. In particular, the irradiated film keeps the giant magnetocaloric effect at room temperature opening new perspective on magnetic refrigeration technology for everyday use.

Trassinelli, M., E-mail: martino.trassinelli@insp.jussieu.fr; Marangolo, M.; Eddrief, M.; Etgens, V. H.; Gafton, V.; Hidki, S.; Lacaze, E.; Lamour, E.; Prigent, C.; Rozet, J.-P.; Steydli, S.; Zheng, Y.; Vernhet, D. [CNRS, UMR 7588, Institut des NanoSciences de Paris (INSP), F-75005 Paris (France); Sorbonne Universités, UPMC Univ. Paris 06, UMR 7588, INSP, F-75005 Paris (France)

2014-02-24T23:59:59.000Z

377

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

378

Photoconductivity of germanium tin alloys grown by molecular beam epitaxy  

SciTech Connect (OSTI)

Photocurrent spectroscopy was used to measure the infrared absorption of germanium-tin alloys grown by molecular beam epitaxy. To study dependence on Sn composition, the photocurrent was measured at 100 K on alloys of Ge{sub 1-x}Sn{sub x} with atomic percentages of Sn up to 9.8%. The optical absorption coefficient was calculated from the photocurrent, and it was found that the absorption edge and extracted bandgap energy decreased with increasing Sn content. For all Ge{sub 1-x}Sn{sub x} samples, a fundamental bandgap below that of bulk Ge was observed, and a bandgap energy as low as 0.624 eV was found for a Sn percentage of 9.8% at 100 K.

Coppinger, Matthew; Hart, John; Bhargava, Nupur; Kim, Sangcheol; Kolodzey, James [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)] [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)

2013-04-08T23:59:59.000Z

379

The Characteristics of Polysilicon Oxide Grown on Amorphous Silicon Deposited from Disilane  

Science Journals Connector (OSTI)

The characteristics of polysilicon oxide (polyoxide) grown on amorphous silicon deposited from disilane as the silicon source are reported on. The rate of amorphous silicon deposition from disilane is comparable to that of polysilicon deposition from silane. Moreover, the obtained polyoxide has the desirable electrical characteristics of lower leakage current and higher breakdown field than those of polyoxide grown on polysilicon deposition from silane, urgently needed for nonvolatile memory application. At the same time, the grown polysilicon oxides have lower electron trapping rates and larger charge-to-breakdown (Q bd), both attributable to their smoother polyoxide/polysilicon-1 interface than those of polyoxides grown on polysilicon deposition from silane.

Yeou Ming Lin; Tan Fu Lei

1997-01-01T23:59:59.000Z

380

Characterization of epitaxial graphene grown on silicon carbide; Karaktärisering av epitaxiellt grafen växt på kiselkarbid.  

E-Print Network [OSTI]

?? In this thesis work several manufacturing methods for graphene is discussed followed by an indepth study of graphene grown by a high temperature sublimation… (more)

Jansson, Anton

2014-01-01T23:59:59.000Z

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.


381

THz Quantum Cascade Lasers Grown by Low-Pressure Metalorganic Vapor Phase Epitaxy  

Science Journals Connector (OSTI)

A terahertz quantum cascade laser (QCL) has been successfully grown by low-pressure MOVPE. Very high quality semiconductor interfaces are demonstrated as well as very promising lasing...

Sirigu, Lorenzo; Rudra, Alok; Amanti, Maria I; Scalari, Giacomo; Fischer, Milan; Giovannini, Marcella; Faist, Jerome; Kapon, Eli

382

E-Print Network 3.0 - aspergillus parasiticus grown Sample Search...  

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

Topic List Advanced Search Sample search results for: aspergillus parasiticus grown Page: << < 1 2 3 4 5 > >> 1 Mycopathologia 153: 4148, 2001. 2002 Kluwer Academic...

383

Properties of boron-doped thin films of polycrystalline silicon  

SciTech Connect (OSTI)

The properties of polycrystalline-silicon films deposited by low pressure chemical vapor deposition and doped heavily in situ boron-doped with concentration level of around 2×10{sup 20}cm{sup ?3} has been studied. Their properties are analyzed using electrical and structural characterization means by four points probe resistivity measurements and X-ray diffraction spectra. The thermal-oxidation process are performed on sub-micron layers of 200nm/c-Si and 200nm/SiO{sub 2} deposited at temperatures T{sub d} ranged between 520°C and 605°C and thermally-oxidized in dry oxygen ambient at 945°C. Compared to the as-grown resistivity with silicon wafers is known to be in the following sequence < and < . The measure X-ray spectra is shown, that the Bragg peaks are marked according to the crystal orientation in the film deposited on bare substrates (poly/c-Si), for the second series of films deposited on bare oxidized substrates (poly/SiO{sub 2}) are clearly different.

Merabet, Souad [Electronic Department, Faculty of Science and Technology, University of Jijel, Cité Ouled-Aissa B. P. 98 Jijel, 18 000 Jijel (Algeria)

2013-12-16T23:59:59.000Z

384

NFRC Procedures for Applied Films  

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

385

Modeling and control of thin film surface morphology: application to thin film solar cells  

E-Print Network [OSTI]

materials, thin film solar cell technology stands to benefitThin-film solar cells: Review of materials, technologies and

Huang, Jianqiao

2012-01-01T23:59:59.000Z

386

Fatty Acid Composition of Cladosporium resinae Grown on Glucose and on Hydrocarbons  

Science Journals Connector (OSTI)

...fatty acids than cells grown on the other...n-tridecane-grown cells. Thus, the fatty...Essential 0 Fossil Fuels 0 Kerosene 0 Petroleum...Glucose metabolism Hydrogen-Ion Concentration...commercial aviation fuel; and on a series...n-tetra- decane. Cell yield was greatest...

J. J. Cooney; C. M. Proby

1971-11-01T23:59:59.000Z

387

Biomass, Flavonol Levels and Sensory Characteristics of Allium cultivars Grown Hydroponically at Ambient and  

E-Print Network [OSTI]

04ICES-136 Biomass, Flavonol Levels and Sensory Characteristics of Allium cultivars Grown growth chambers to evaluate the effect of elevated CO2 (1200 ppm) versus ambient CO2 (400 ppm) on biomass planting (dap). Regardless of cultivar or dap, plants grown at elevated CO2 had greater biomass

Paré, Paul W.

388

Trapping cold atoms using surface-grown carbon nanotubes P. G. Petrov,1,* S. Machluf,1  

E-Print Network [OSTI]

Trapping cold atoms using surface-grown carbon nanotubes P. G. Petrov,1,* S. Machluf,1 S. Younis,1 atomic clouds into magnetic traps created by single-wall carbon nanotubes grown directly onto dielectric surfaces. We show that atoms may be captured for experimen- tally sustainable nanotube currents, generating

Joselevich, Ernesto

389

Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia  

SciTech Connect (OSTI)

Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300?°C from three recently synthesized M[N(t-Bu){sub 2}]{sub 2} precursors, where M?=?Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200?°C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18?nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities.

Cloud, Andrew N.; Abelson, John R., E-mail: abelson@illinois.edu [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 W. Green St., Urbana, Illinois 61801 (United States); Davis, Luke M.; Girolami, Gregory S., E-mail: girolami@scs.illinois.edu [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801 (United States)

2014-03-15T23:59:59.000Z

390

Defect studies in low-temperature-grown GaAs  

SciTech Connect (OSTI)

High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V{sub Ga}. The neutral AsGa-related defects were measured by infrared absorption at 1{mu}m. Gallium vacancies, V{sub Ga}, was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10{sup 19} cm{sup {minus}3} Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As{sub Ga} in the layer. As As{sub Ga} increases, photoquenchable As{sub Ga} decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As{sub Ga} content around 500C, similar to irradiation damaged and plastically deformed Ga{sub As}, as opposed to bulk grown GaAs in which As{sub Ga}-related defects are stable up to 1100C. The lower temperature defect removal is due to V{sub Ga} enhanced diffusion of As{sub Ga} to As precipitates. The supersaturated V{sub GA} and also decreases during annealing. Annealing kinetics for As{sub Ga}-related defects gives 2.0 {plus_minus} 0.3 eV and 1.5 {plus_minus} 0.3 eV migration enthalpies for the As{sub Ga} and V{sub Ga}. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As{sub Ga}-related defects anneal with an activation energy of 1.1 {plus_minus} 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As{sub Ga}-Be{sub Ga} pairs. Si donors can only be partially activated.

Bliss, D.E.

1992-11-01T23:59:59.000Z

391

Defect studies in low-temperature-grown GaAs  

SciTech Connect (OSTI)

High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

Bliss, D.E.

1992-11-01T23:59:59.000Z

392

The MBE growth and optical quality of BaTiO{sub 3} and SrTiO{sub 3} thin films on MgO  

SciTech Connect (OSTI)

High quality epitaxial BaTiO{sub 3} and SrTiO{sub 3} have been grown on MgO; stabilized at a one unit cell height; and grown to film thicknesses of 0.5--0.7 {mu}m. These relatively thick films remain adherent when thermally cycled between growth temperatures and room temperature, are crack free with high optical quality, and have both in-plane and out-of-plane X-ray rocking curves of 0.3--0.5{degree}. These films have been grown using molecular beam epitaxy (MBE) methods starting with the TiO{sub 2} layer of the perovskite structure. The TiO{sub 2}-layer/MgO interface uniquely satisfies electrostatic requirements for perovskite heteroepitaxy and provides the template structure that leads to the high quality films that are obtained. Wavelength dependence of optical loss has been characterized between 475 nm and 705 nm with loss coefficients < l dB/cm being obtained at the He-Ne wavelength.

McKee, R.A.; Specht, E.D.; Alexander, K.B. [Oak Ridge National Lab., TN (United States); Walker, F.J. [Tennessee Univ., Knoxville, TN (United States)

1994-05-01T23:59:59.000Z

393

Fabrication and characterization of ferroelectric PLZT film capacitors on metallic substrates.  

SciTech Connect (OSTI)

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 Hastelloy C276 (HC) substrates by chemical solution deposition. Samples of 1.15-{micro}m-thick PLZT films were prepared on HC with and without lanthanum nickel oxide (LNO) films as an intermediate buffer layer. On samples with and without LNO buffers at room temperature, we measured dielectric constants of {approx}1,300 and {approx}450 and loss tangents of {approx}0.06 and {approx}0.07, respectively. For PLZT films grown on HC with LNO buffer, the dielectric constant increases, while the dielectric loss decreases, with increasing temperature. A dielectric constant of {approx}2,000 and loss of {approx}0.05 were observed at 150 C. Samples with LNO buffer also exhibited slimmer hysteresis loops and lower leakage current density when compared to samples without LNO buffer. The following results were measured on samples with and without LNO buffers: remanent polarization (P{sub r}) values of 21.3 and 36.4 {micro}C/cm{sup 2}, coercive electric field (E{sub c}) values of 41 and 173 kV/cm, and leakage current densities of {approx}1.1 x 10{sup -8} and {approx}1.6 x 10{sup -7} A/cm{sup 2}, respectively. The energy storage capability was measured at {approx}65 J/cm{sup 3} for the PLZT film-on-foil capacitor deposited on HC with LNO buffer.

Ma, B.; Narayanan, M.; Tong, S.; Balachandran, U.; Energy Systems

2010-01-01T23:59:59.000Z

394

Properties of ferroelectric/ferromagnetic thin film heterostructures  

SciTech Connect (OSTI)

Ferroelectric/ferromagnetic thin film heterostructures, SrBi{sub 2}Ta{sub 2}O{sub 9}/BaFe{sub 12}O{sub 19} (SBT/BaM), were grown on platinum-coated Si substrates using metal-organic decomposition. X-ray diffraction patterns confirmed that the heterostructures contain only SBT and BaM phases. The microwave properties of these heterostructures were studied using a broadband ferromagnetic resonance (FMR) spectrometer from 35 to 60 GHz, which allowed us to determine gyromagnetic ratio and effective anisotropy field. The FMR linewidth is as low as140 Oe at 58 GHz. In addition, measurements of the effective permittivity of the heterostructures were carried out as a function of bias electric field. All heterostructures exhibit hysteretic behavior of the effective permittivity. These properties indicate that such heterostructures have potential for application in dual electric and magnetic field tunable resonators, filters, and phase shifters.

Chen, Daming, E-mail: chendaming1986@gmail.com [Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054 Sichuan (China); Harward, Ian; Linderman, Katie; Economou, Evangelos; Celinski, Zbigniew [Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); Nie, Yan [Center for Magnetism and Magnetic Nanostructures, University of Colorado Colorado Springs, 1420 Austin Bluffs Pkwy, Colorado Springs, Colorado 80918 (United States); School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074 (China)

2014-05-07T23:59:59.000Z

395

Measuring droplet impact with piezoelectric film  

E-Print Network [OSTI]

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...

Basahi, Jalal M. Al-Badry M.

2012-06-07T23:59:59.000Z

396

Templated dewetting of thin solid films  

E-Print Network [OSTI]

The dewetting of solid metal polycrystalline films to form metal nanoparticles occurs by the nucleation and growth of holes in the film. For typical films on flat substrates, this process is not well-controlled and results ...

Giermann, Amanda L. (Amanda Leah)

2009-01-01T23:59:59.000Z

397

Big-Data RHEED analysis for understanding epitaxial film growth processes  

SciTech Connect (OSTI)

Reflection high energy electron diffraction (RHEED) has by now become a standard tool for in-situ monitoring of film growth by pulsed laser deposition and molecular beam epitaxy. Yet despite the widespread adoption and wealth of information in RHEED image, most applications are limited to observing intensity oscillations of the specular spot, and much additional information on growth is discarded. With ease of data acquisition and increased computation speeds, statistical methods to rapidly mine the dataset are now feasible. Here, we develop such an approach to the analysis of the fundamental growth processes through multivariate statistical analysis of RHEED image sequence. This approach is illustrated for growth of LaxCa1-xMnO3 films grown on etched (001) SrTiO3 substrates, but is universal. The multivariate methods including principal component analysis and k-means clustering provide insight into the relevant behaviors, the timing and nature of a disordered to ordered growth change, and highlight statistically significant patterns. Fourier analysis yields the harmonic components of the signal and allows separation of the relevant components and baselines, isolating the assymetric nature of the step density function and the transmission spots from the imperfect layer-by-layer (LBL) growth. These studies show the promise of big data approaches to obtaining more insight into film properties during and after epitaxial film growth. Furthermore, these studies open the pathway to use forward prediction methods to potentially allow significantly more control over growth process and hence final film quality.

Vasudevan, Rama K [ORNL; Tselev, Alexander [ORNL; Baddorf, Arthur P [ORNL; Kalinin, Sergei V [ORNL

2014-01-01T23:59:59.000Z

398

A new LPCVD technique of producing borophosphosilicate glass films by injection of miscible liquid precursors  

SciTech Connect (OSTI)

This study introduces a new, simple, and viable LPCVD technique based on the injection of miscible liquid precursors. The preparation of BPSG films from liquid mixtures of TEOS, TMB, and TMP is used here as a prime example for implementing this concept. The relationship between starting solution composition and resulting film composition is investigated to provide guidelines for achieving desired stoichiometries. Variations in growth rate and composition are examined to assess the relative effects of deposition temperature, total pressure, solution composition, and injection rate. At the high boron and phosphorus levels (greater than or equal to4 weight percent), the reaction chemistry associated with the use of TMP is seen to produce severe depletion effects. At optimum deposition conditions, select properties of BPSG films are investigated. The results indicate high compositional uniformity within the film, a dielectric constant value in close agreement with that of thermally grown, SiO/sub 2/, conformal step coverage even in the case of severe aspect ratios, and desirable flow profiles at temperatures and phosphorus concentrations significantly lower than those being currently achieved with phosphosilicate glass films.

Levy, R.A.; Gallagher, P.K.; Schrey, F.

1987-02-01T23:59:59.000Z

399

Bulk diffusion induced structural modifications of carbon-transition metal nanocomposite films  

SciTech Connect (OSTI)

The influence of transition metal (TM = V,Co,Cu) type on the bulk diffusion induced structural changes in carbon:TM nanocomposite films is investigated. The TMs have been incorporated into the carbon matrix via ion beam co-sputtering, and subsequently the films have been vacuum annealed in the temperature range of 300 - 700 deg. C. The structure of both the dispersed metal rich and the carbon matrix phases has been determined by a combination of elastic recoil detection analysis, x-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The as-grown films consist of carbidic (V and Co) and metallic (Cu) nanoparticles dispersed in the carbon matrix. Thermal annealing induces surface segregation of Co and Cu starting at {>=} 500 deg. C, preceded by the carbide-metal transformation of Co-carbide nanoparticles at {approx} 300 deg. C. No considerable morphological changes occur in C:V films. In contrast to the surface diffusion dominated regime where all the metals enhance the six-fold ring clustering of C, in the bulk diffusion controlled regime only Co acts as a catalyst for the carbon graphitization. These results are consistent with the metal-induced crystallization mechanism in the C:Co films. The results are discussed on the basis of the metal-carbide phase stability, carbon solubility in metals or their carbides, and interface species.

Berndt, M.; Abrasonis, G.; Kovacs, Gy. J.; Krause, M.; Munnik, F.; Heller, R.; Kolitsch, A.; Moeller, W.

2011-03-15T23:59:59.000Z

400

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

SciTech Connect (OSTI)

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

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

Electrocodeposition of nanoparticle composite films using an impinging jet electrode  

E-Print Network [OSTI]

Electrocodeposition of Nanoparticle Composite Films Using anElectrocodeposition of Nanoparticle Composite Films Using an

Osborne, Steven J.

2006-01-01T23:59:59.000Z

402

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

SciTech Connect (OSTI)

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

403

Applied Films Corporation | Open Energy Information  

Open Energy Info (EERE)

Name: Applied Films Corporation Place: Longmont, Colorado Zip: 80504 Sector: Services, Solar Product: Provider of thin film deposition equipment and services, particularly to...

404

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

405

Hybrid Thin Film Deposition System | EMSL  

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

Hybrid Thin Film Deposition System Hybrid Thin Film Deposition System Only available at EMSL, the Discovery Deposition System has been customized to be a fully automated...

406

Thin Film Solar Technologies | Open Energy Information  

Open Energy Info (EERE)

Jump to: navigation, search Name: Thin Film Solar Technologies Place: South Africa Product: Producers of thin-film copper, indium, gallium, sulphur, selenium modules....

407

Substitutional incorporation of Sn in compressively strained thin films of heavily-alloyed Ge1 ? xSn  

Science Journals Connector (OSTI)

Short-range-order and long-range-order structures in Ge1 ? xSn x /Ge thin films grown by molecular beam epitaxy (MBE) were investigated by using extended x-ray absorption fine structure (EXAFS) and x-ray diffraction (XRD) techniques, respectively. These materials are of great potential for constructing efficient optoelectronic devices. The EXAFS analysis demonstrates that Sn atoms occupy Ge sites in these thin-film samples with Sn concentration up to 20 at.%. The Ge-Sn bonds expected in the substitutional model were also observed in Raman spectra of these samples. The XRD results show that, in the out-of-plane direction, the lattice constants of the films are distinctly larger than that of the Ge substrates. However, such increased lattice parameters were not observed in the in-plane direction. Our x-ray and Raman results have clearly revealed substitutional incorporation of Sn with high concentration in dislocation-free MBE-grown Ge films of practical-device thickness.

Y L Soo; T S Wu; Y C Chen; Y F Shiu; H J Peng; Y W Tsai; P Y Liao; Y Z Zheng; S L Chang; T S Chan; J F Lee; G E Sterbinsky; H Li; H H Cheng

2014-01-01T23:59:59.000Z

408

Fact #844: October 27, 2014 Electricity Generated from Coal has Declined while Generation from Natural Gas has Grown – Dataset  

Broader source: Energy.gov [DOE]

Excel file with dataset for Fact #844: Electricity Generated from Coal has Declined while Generation from Natural Gas has Grown

409

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

410

Thin film hydrogen sensor  

DOE Patents [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

411

Metal oxide films on metal  

DOE Patents [OSTI]

A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

Wu, Xin D. (Los Alamos, NM); Tiwari, Prabhat (Los Alamos, NM)

1995-01-01T23:59:59.000Z

412

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

413

Te INCLUSIONS IN CdTe GROWN FROM A SLOWLY COOLED Te SOLUTION AND BY THE TRAVELLING SOLVENT METHOD  

E-Print Network [OSTI]

135 Te INCLUSIONS IN CdTe GROWN FROM A SLOWLY COOLED Te SOLUTION AND BY THE TRAVELLING SOLVENT. Abstract. 2014 CdTe crystals have been grown from a slowly cooled Te solution and with the travelling. Introduction. - CdTe crystals for nuclear radia- tion detectors are usually grown from a slowly cooled solution

Paris-Sud XI, Université de

414

Genomic and Transcriptomic Analyses of the Facultative Methanotroph Methylocystis sp. Strain SB2 Grown on Methane or Ethanol  

Science Journals Connector (OSTI)

...Methylocystis sp. Strain SB2 Grown on Methane or Ethanol Alexey Vorobev a Sheeja Jagadevan a Sunit...cultures grown with either methane or ethanol. Evidence for use of the canonical methane...Methylocystis sp. strain SB2 grown with ethanol compared to methane revealed that on ethanol...

Alexey Vorobev; Sheeja Jagadevan; Sunit Jain; Karthik Anantharaman; Gregory J. Dick; Stéphane Vuilleumier; Jeremy D. Semrau

2014-03-07T23:59:59.000Z

415

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

SciTech Connect (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

416

Growth of epitaxial PrO sub 2 thin films on hydrogen terminated Si (111) by pulsed laser deposition  

SciTech Connect (OSTI)

A new epitaxial oxide, PrO{sub 2}, has been grown on Si (111) by pulsed laser deposition. X-ray diffraction shows that films are oriented with the PrO{sub 2}(111) direction parallel to the substrate (111). The full width at half maximum for the omega rocking curve on the PrO{sub 2} (222) peak is as low as 0.75{degree}, while phi scans indicate {ital in}-{ital plane} epitaxial alignment to better than one degree. In the best quality films, epitaxy is almost pure type-{ital b} epitaxy which is characteristic of epitaxial CaF{sub 2} on Si. To achieve epitaxy, it is essential to remove the native silicon oxide from the substrate prior to film growth. This is done at room temperature using a wet-chemical hydrogen-termination procedure.

Fork, D.K. (Xerox Palo Alto Research Center, Palo Alto, CA (USA) Department of Applied Physics, Stanford University, Stanford, CA (USA)); Fenner, D.B. (Xerox Palo Alto Research Center, Palo Alto, CA (USA) Santa Clara University, Physics Department, Santa Clara, CA (USA)); Geballe, T.H. (Department of Applied Physics, Stanford University, Stanford, CA (USA))

1990-10-15T23:59:59.000Z

417

Spin- and angle-resolved photoemission study of chemisorbed p(1×1) O on epitaxial ultrathin Fe/W(001) films  

Science Journals Connector (OSTI)

Chemisorbed p(1×1) oxygen on ultrathin epitaxial Fe films grown on W(001) are studied using spin- and angle-resolved photoemission. In agreement with theoretical predictions, single-monolayer (ML) Fe films on W(001) are found to be nonmagnetic; 2-ML-thick Fe films are magnetic, and chemisorbed p(1×1) oxygen does not destroy the magnetism. Even- and odd-symmetry oxygen 2p-derived bands are measured along the ?¯-X¯ and ?¯-M¯ directions of the two-dimensional Brillouin zone. Oxygen-derived features in the photoemission spectra exhibit magnetic exchange splitting as well as spin-dependent intrinsic linewidths that are governed by lifetime effects and initial-state mixing with Fe bands. Oxygen 2p-band narrowing resulting from the expanded Fe thin-film lattice constant is observed. The results are compared with relevant calculations and corresponding experimental studies of p(1×1) oxygen on bulk Fe(001) surfaces.

R. L. Fink; G. A. Mulhollan; A. B. Andrews; J. L. Erskine; G. K. Walters

1992-05-01T23:59:59.000Z

418

Anomalous scaling and super-roughness in the growth of CdTe polycrystalline films  

E-Print Network [OSTI]

CdTe films grown on glass substrates covered by fluorine doped tin oxide by Hot Wall Epitaxy (HWE) were studied through the interface dynamical scaling theory. Direct measures of the dynamical exponent revealed an intrinsically anomalous scaling characterized by a global roughness exponent $\\alpha$ distinct from the local one (the Hurst exponent $H$), previously reported [Ferreira \\textit{et al}., Appl. Phys. Lett. \\textbf{88}, 244103 (2006)]. A variety of scaling behaviors was obtained with varying substrate temperature. In particular, a transition from a intrinsically anomalous scaling regime with $H\

Angélica S. Mata; Silvio C. Ferreira, Jr.; Igor R. B. Ribeiro; Sukarno O. Ferreira

2011-01-06T23:59:59.000Z

419

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

SciTech Connect (OSTI)

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

420

Effective phase control of silicon films during high-rate deposition in atmospheric-pressure very high-frequency plasma: Impacts of gas residence time on the performance of bottom-gate thin film transistors  

Science Journals Connector (OSTI)

Abstract Hydrogenated amorphous silicon (a-Si) and microcrystalline silicon (?c-Si) films were grown in atmospheric-pressure (AP) He/H2/SiH4 plasma excited by a 150-MHz very high-frequency (VHF) power at a temperature of 220 °C. The variations in thickness and crystallinity of the deposited Si films along the gas flow direction were studied as functions of gas residence time in the plasma, VHF power density and H2 flow rate. Furthermore, the electrical characteristics of bottom-gate thin film transistors (TFTs) were investigated to evaluate the film quality. The results revealed that the chemical reactions both in gas phase and on the growing film surface were significantly enhanced in AP-VHF plasma, promoting phase transition from amorphous to microcrystalline in a time of the order of 0.1 ms. The performance of the \\{TFTs\\} showed that a-Si layers formed in the upstream portion of the plasma zone had reasonably good electrical property (field-effect mobility of approximately 2 cm2/V s) despite very high deposition rates around 20 nm/s. While ?c-Si layers deposited in the downstream portion were very defective, which might come from the insufficient passivation of grain boundaries with a-Si tissues due to a too long gas residence time in the plasma. The precise control of gas residence time by adjusting the length of plasma will be effective for the phase control of Si films with desired quality.

H. Kakiuchi; H. Ohmi; T. Yamada; A. Hirano; T. Tsushima; W. Lin; K. Yasutake

2013-01-01T23:59:59.000Z

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

Growth, nitrogen utilization and biodiesel potential for two chlorophytes grown on ammonium, nitrate or urea  

Science Journals Connector (OSTI)

Nitrogen removal from wastewater by algae provides the potential benefit of producing lipids for biodiesel and biomass for anaerobic digestion. Further,...Scenedesmus sp. 131 and Monoraphidium sp. 92 were grown w...

Everett Eustance; Robert D. Gardner; Karen M. Moll…

2013-12-01T23:59:59.000Z

422

E-Print Network 3.0 - affects full-grown body Sample Search Results  

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

of the body. It is an inch long when full grown. Cloverworms feed... a light silken web which the caterpillars spin over foliage and other parts of the plant. When...

423

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

424

MagLab - Science in Literature: Fiction for Grown-Ups  

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

Fiction for Grown-Ups Skillful authors weave real science into plots featuring swashbuckling heroes, famed physicists and a Dorothy clone lost not in the Land of Oz, but of Quarks....

425

In less than 40 years Linkping University has grown into one of Sweden's largest academic institutions  

E-Print Network [OSTI]

#12;#12;3 In less than 40 years Linköping University has grown into one of Sweden's largest much emphasis on internationalisation and cooperation at Linköping University. Sweden is often cited

Zhao, Yuxiao

426

Development of a Scanning Probe Microscope and Studies of Graphene Grown on Copper  

E-Print Network [OSTI]

of Graphene Grown on Copper (100) Single Crystals,” JournalGraphene on Polycrystalline Copper,” Nano Letters 11, 251 (5 GRAPHENE GROWTH ON COPPER (100) SINGLE CRYSTALS 5.1

Rasool, Haider Imad

2012-01-01T23:59:59.000Z

427

Silicon Thin-Film Formation by Direct Photochemical Decomposition of Disilane  

Science Journals Connector (OSTI)

Silicon thin-films have been deposited by the direct photolysis of disilane at a substrate temperature below 300°C. The growth rate depends on irradiation intensity of a low pressure mercury-lamp, and a typical rate of 15 Å/min has been obtained under ~0.08 watts/cm2 illumination, regardless of substrate temperature. The deposited films are composed of an amorphous network containing bonded-hydrogen in the range 6–9 at.%. The bonding configurations of SiH groups varied from silicon dihydride to monohydride with increasing substrate temperature, and correspondingly the dark conductivity decreased from 10-7 to 10-11 ?-1cm-1. A broad photoluminescence peak at 1.4 eV was observed for a specimen grown at 200°C.

Yasuyoshi Mishima; Masataka Hirose; Yukio Osaka; Kunihiro Nagamine; Yoshinori Ashida; Nobuhisa Kitagawa; Kazuyoshi Isogaya

1983-01-01T23:59:59.000Z

428

Atmospheric pressure spatial atomic layer deposition web coating with in situ monitoring of film thickness  

SciTech Connect (OSTI)

Spectral reflectometry was implemented as a method for in situ thickness monitoring in a spatial atomic layer deposition (ALD) system. Al{sub 2}O{sub 3} films were grown on a moving polymer web substrate at 100?°C using an atmospheric pressure ALD web coating system, with film growth of 0.11–0.13?nm/cycle. The modular coating head design and the in situ monitoring allowed for the characterization and optimization of the trimethylaluminum and water precursor exposures, purge flows, and web speed. A thickness uniformity of ±2% was achieved across the web. ALD cycle times as low as 76?ms were demonstrated with a web speed of 1?m/s and a vertical gap height of 0.5?mm. This atmospheric pressure ALD system with in situ process control demonstrates the feasibility of low-cost, high throughput roll-to-roll ALD.

Yersak, Alexander S.; Lee, Yung C. [Department of Mechanical Engineering, University of Colorado at Boulder, 1045 Regent Drive, 422 UCB, Boulder, Colorado 80309-0422 (United States); Spencer, Joseph A.; Groner, Markus D., E-mail: mgroner@aldnanosolutions.com [ALD NanoSolutions, Inc., 580 Burbank Street, Unit 100, Broomfield, Colorado 80020 (United States)

2014-01-15T23:59:59.000Z

429

Suppression of photocatalytic efficiency in highly N-doped anatase films  

SciTech Connect (OSTI)

We report the role of N in epitaxial films of anatase TiO{sub 2}. The films were artificially grown with a two-step temperature-tuned epitaxy which utilized the high-temperature cubic phase of LaAlO{sub 3} substrates. The preparation of highly crystallized anatase with various N concentrations (C{sub N}{<=}3.85 at. %) allowed us to identify the optimum dopant concentration (C{sub N}=1-2 at. %). At higher doping levels, N is found to be difficult to substitute for O having been predicted to contribute to the band-gap narrowing, giving rise to the undesirable deep-level defects. In addition, a study by x-ray and Raman spectroscopy revealed that the growth of anatase became more difficult, and the stable phase was shifted to rutile at the higher N concentrations.

Okato, Takeshi; Sakano, Tatsunori; Obara, Minoru [Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama-shi, 223-8522 (Japan)

2005-09-15T23:59:59.000Z

430

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

SciTech Connect (OSTI)

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

431

Growth and fruiting responses of diverse genotypes of American Upland cotton grown in different environments  

E-Print Network [OSTI]

GROWTH AND FRUITING RESPONSES OF DIVERSE GENOTYPES OF AMERICAN UPLAND COTTON GROWN IN DIFFERENT ENVIRONMENTS A Thesis JOHN ROBERT GANNAWAY Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE May 1971 Major Subject: Plant Breeding GROWTH AND FRUITING RESPONSES OF DIVERSE GENOTYPES OF AMERICAN UPLAND COTTON GROWN IN DIFFERENT ENVIRONMENTS A Thesis by JOHN ROBERT GANNAWAY Approved as to style and content by...

Gannaway, J. R

2012-06-07T23:59:59.000Z

432

Optimum fertilization rate for intermediate leaf cucumber grown for once-over mechanical harvest  

E-Print Network [OSTI]

OPTIMUM FERTILIZATION RATE FOR INTERMEDIATE LEAF CUCUMBER GROWN FOR ONCE-OVER MECHANICAL HARVEST A Thesis by TIMOTHY MICHAEL KONDERLA Submitted to the Office of Graduate Studies of Texas A& M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 1992 Major Subject: Horticulture OPTIMUM FERTILIZATION RATE FOR INTERMEDIATE LEAF CUCUMBER GROWN FOR ONCE-OVER MECHANICAL HARVEST A Thesis by TIMOTHY MICHAEL KONDERLA Approved as to style...

Konderla, Timothy Michael

1992-01-01T23:59:59.000Z

433

Energy band alignment of atomic layer deposited HfO{sub 2} on epitaxial (110)Ge grown by molecular beam epitaxy  

SciTech Connect (OSTI)

The band alignment properties of atomic layer HfO{sub 2} film deposited on epitaxial (110)Ge, grown by molecular beam epitaxy, was investigated using x-ray photoelectron spectroscopy. The cross-sectional transmission electron microscopy exhibited a sharp interface between the (110)Ge epilayer and the HfO{sub 2} film. The measured valence band offset value of HfO{sub 2} relative to (110)Ge was 2.28 {+-} 0.05 eV. The extracted conduction band offset value was 2.66 {+-} 0.1 eV using the bandgaps of HfO{sub 2} of 5.61 eV and Ge bandgap of 0.67 eV. These band offset parameters and the interface chemical properties of HfO{sub 2}/(110)Ge system are of tremendous importance for the design of future high hole mobility and low-power Ge-based metal-oxide transistor devices.

Hudait, M. K.; Zhu, Y. [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Maurya, D.; Priya, S. [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)

2013-03-04T23:59:59.000Z

434

One Nanometer Thickness Specimen Supporting Film  

Science Journals Connector (OSTI)

......carbon ultra thin film coated on the micro-grid is developed for the electron microscopy...carbon ultra thin film coated on the micro-grid is developed for the electron microscopy...specimen supporting film, which is a micro-grid coated with carbon thin film of......

Shigeo Sakata; Shinsuke Hotsumi; Hiroyuki Watanabe

1991-02-01T23:59:59.000Z

435

The development of potassium tantalate niobate thin films for satellite-based pyroelectric detectors  

SciTech Connect (OSTI)

Potassium tantalate niobate (KTN) pyroelectric detectors are expected to provide detectivities, of 3.7 x 10{sup 11} cmHz {sup {1/2}}W{sup {minus}1} for satellite-based infrared detection at 90 K. The background limited detectivity for a room-temperature thermal detector is 1.8 x 10{sup 10} cmHz{sup {1/2}}W{sup {minus}1}. KTN is a unique ferroelectric for this application because of the ability to tailor the temperature of its pyroelectric response by adjusting its ratio of tantalum to niobium. The ability to fabricate high quality KTN thin films on Si-based substrates is crucial to the development of KTN pyroelectric detectors. Si{sub x}N{sub y} membranes created on the Si substrate will provide the weak thermal link necessary to reach background limited detectivities. The device dimensions obtainable by thin film processing are expected to increase the ferroelectric response by 20 times over bulk fabricated KTN detectors. In addition, microfabrication techniques allow for easier array development. This is the first reported attempt at growth of KTN films on Si-based substrates. Pure phase perovskite films were grown by pulsed laser deposition on SrRuO{sub 3}/Pt/Ti/Si{sub x}N{sub y}/Si and SrRuO{sub 3}/Si{sub x}N{sub y}/Si structures; room temperature dielectric permittivities for the KTN films were 290 and 2.5, respectively. The dielectric permittivity for bulk grown, single crystal KTN is {approximately}380. In addition to depressed dielectric permittivities, no ferroelectric hysteresis was found between 80 and 300 K for either structure. RBS, AES, TEM and multi-frequency dielectric measurements were used to investigate the origin of this apparent lack of ferroelectricity. Other issues addressed by this dissertation include: the role of oxygen and target density during pulsed laser deposition of KTN thin films; the use of YBCO, LSC and Pt as direct contact bottom electrodes to the KTN films, and the adhesion of the bottom electrode layers to Si{sub x}N{sub y}/Si.

Cherry, H.B.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States)

1997-05-01T23:59:59.000Z

436

CFN | Thin Films Group  

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

437

Ferromagnetic thin films  

DOE Patents [OSTI]

A ferromagnetic [delta]-Mn[sub 1[minus]x]Ga[sub x] thin film having perpendicular anisotropy is described which comprises: (a) a GaAs substrate, (b) a layer of undoped GaAs overlying said substrate and bonded thereto having a thickness ranging from about 50 to about 100 nanometers, (c) a layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] overlying said layer of undoped GaAs and bonded thereto having a thickness ranging from about 20 to about 30 nanometers, and (d) a layer of GaAs overlying said layer of [delta]-Mn[sub 1[minus]x]Ga[sub x] and bonded thereto having a thickness ranging from about 2 to about 5 nanometers, wherein x is 0.4[+-]0.05. 7 figures.

Krishnan, K.M.

1994-12-20T23:59:59.000Z

438

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

439

Growth-induced magnetic anisotropy and clustering in vapor-deposited Co-Pt alloy films A. L. Shapiro, P. W. Rooney, M. Q. Tran, and F. Hellman  

E-Print Network [OSTI]

. Shapiro, P. W. Rooney, M. Q. Tran, and F. Hellman Department of Physics, University of California to 800 °C. Films grown at moderate temperatures 200­400 °C exhibit remarkable growth-induced properties chemical order develops, such that below 800 °C, near the Co0.50Pt0.50 composition, CoxPt1 x exhibits Cu

Hellman, Frances

440

Optical phonon modes in InGaN/GaN dot-in-a-wire heterostructures grown by molecular beam epitaxy  

SciTech Connect (OSTI)

We report on the studies of optical phonon modes in nearly defect-free GaN nanowires embedded with intrinsic InGaN quantum dots by using oblique angle transmission infrared spectroscopy. These phonon modes are dependent on the nanowire fill-factor, doping densities of the nanowires, and the presence of InGaN dots. These factors can be applied for potential phonon based photodetectors whose spectral responses can be tailored by varying a combination of these three parameters. The optical anisotropy along the growth (c-) axis of the GaN nanowire contributes to the polarization agility of such potential photodetectors.

Titus, J.; Perera, A. G. U. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States)] [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Nguyen, H. P. T.; Mi, Z. [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada)] [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 2A7 (Canada)

2013-03-25T23:59:59.000Z

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

As-Received, Ozone Cleaned and Ar+ Sputtered Surfaces of Hafnium Oxide Grown by Atomic Layer Deposition and Studied by XPS  

SciTech Connect (OSTI)

In this study, X-ray photoelectron spectroscopy (XPS) characterization was performed on 47 nm thick hafnium oxide (HfO{sub 2}) films grown by atomic layer deposition using TEMA-Hf/H{sub 2}O at 250 C substrate temperature. HfO{sub 2} is currently being studied as a possible replacement for Silicon Oxide (SiO{sub 2}) as a gate dielectric in electronics transistors. XPS spectra were collected on a Physical Electronics Quantum 2000 Scanning ESCA Microprobe using a monochromatic Al K{sub a} X-ray (1486.7 eV) excitation source. The sample was analyzed under the following conditions: as received, after UV irradiation for five minutes, and after sputter cleaning with 2 kV Ar{sup +} ions for 180 seconds. Survey scans showed carbon, oxygen, and hafnium as the major species in the film, while the only minor species of argon and carbide was detected after sputtering. Adventitious carbon initially composed approximately 18.6 AT% of the surface, but after UV cleaning it was reduced to 2.4 AT%. This demonstrated that that the majority of carbon was due to adventitious carbon. However, after 2 kV Ar{sup +} sputtering there was still only trace amounts of carbon at {approx}1 AT%, Some of this trace carbon is now in the form of a carbide due to the interaction with Ar{sup +} used for sputter cleaning. Furthermore, the stoiciometric ratio of oxygen and hafnium is consistent with a high quality HfO{sub 2} film.

Engelhard, Mark H.; Herman, Jacob A.; Wallace, Robert; Baer, Donald R.

2012-06-27T23:59:59.000Z

442

Wrinkling of Stiff Films on Stretched Compliant Films: Experimental and Theoretical Studies  

E-Print Network [OSTI]

Wrinkling of stiff film on semi-infinite compliant substrates has attracted attentions recently due to its important applications in stretchable electronics and micro-pattern metrology. However, wrinkling of a stiff film on a compliant thin film...

Yang, Yi

2013-12-06T23:59:59.000Z

443

Structural, Morphological and Optical properties of Sputtered Nickel oxide Thin Films  

SciTech Connect (OSTI)

Nickel oxide (NiO) thin films have been deposited by dc reactive magnetron sputtering technique on glass substrates at various substrate temperatures in the range of 303 to 723 K. The influence of substrate temperature on structural, morphological, compositional and optical properties was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS) and spectrophotometer studies. The structural properties of the films were strongly influenced by the substrate temperature. From the microstructural studies, fine and uniform grains were grown with RMS roughness of 9.4 nm at substrate temperature of 523 K. The optical results indicated that the optical transmittance of the films increases with increasing substrate temperature up to 523 K, thereafter decreases. The optical band of the films increases with substrate temperature initially, thereafter decreased at higher temperatures. The Highest optical transmittance of 60 % and optical band gap of 3.82 eV was observed in the present study.

Reddy, A. Mallikarjuna; Reddy, A. Sivasankar; Reddy, P. Sreedhara [Department of Physics, Sri Venkateswara University, Tirupati-517 502 (India)

2011-10-20T23:59:59.000Z

444

Fabrication of amorphous diamond films  

DOE Patents [OSTI]

Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

Falabella, S.

1995-12-12T23:59:59.000Z

445

Improved Electrical Conductivity of Graphene Films Integrated with Metal Nanowires  

E-Print Network [OSTI]

tin oxide films in electrochromic (EC) devices. The successful integration of such graphene/NW films. KEYWORDS: Graphene, nanowires, transparent conductive films, electrochromic devices Due to low electron

446

Review: German Film after Germany. Toward a Transnational Aesthetic  

E-Print Network [OSTI]

Halle. German Film After Germany. Toward a Transnationalof film production in Germany has changed rapidly. Thescale. German Film After Germany: Toward a Transnational

Theisen, Bianca

2011-01-01T23:59:59.000Z

447

Semiconducting p-type MgNiO:Li epitaxial films fabricated by cosputtering method  

SciTech Connect (OSTI)

Li-doped ternary Mg{sub x}Ni{sub 1-x}O thin films were deposited on (0001) Al{sub 2}O{sub 3} substrates by a radio frequency (RF) magnetron cosputtering method with MgO and NiO:Li targets. The Mg mole fraction and Li content were relatively controlled by changing RF power for the MgO target over a range of 0-300 W, while the NiO:Li target was kept at 150 W. As a result, all films were epitaxially grown on (0001) Al{sub 2}O{sub 3} substrates with the relationship of [110]{sub NiO}||[1110]{sub Al2O3}, [112]{sub NiO}||[2110]{sub Al2O3} (in-plane), and [111]{sub NiO}||[0001]{sub Al2O3} (out-of-plane), and showed p-type semiconducting properties. Furthermore, from x-ray diffraction patterns, the authors found that MgO was effectively mixed with NiO:Li without structural deformation due to low lattice mismatch (0.8%) between NiO and MgO. However, the excess Li contents degraded the crystallinity of the MgNiO films. The band-gap of films was continuously shifted from 3.66 eV (339 nm) to 4.15 eV (299 nm) by the RF power of the MgO target. A visible transmittance of more than 80% was exhibited at RF powers higher than 200 W. Ultimately, the electrical resistivity of p-type MgNiO films was improved from 7.5 to 673.5 {Omega}cm, indicating that the Li-doped MgNiO films are good candidates for transparent p-type semiconductors.

Kwon, Yong Hun; Chun, Sung Hyun; Cho, Hyung Koun [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

2013-07-15T23:59:59.000Z

448

Measurements of magnetic screening lengths in superconducting Nb thin films by polarized neutron reflectometry  

Science Journals Connector (OSTI)

Polarized neutron reflectivity measurements have been performed on two polycrystalline niobium films grown on silicon substrates. The samples were characterized with x-ray diffraction and reflection, electrical resistivity, and unpolarized neutron reflection measurements. For the film of 310 nm thickness, polarized neutron reflectivity measurements were carried out on both the Si side as well as the vacuum side, and we found that substantially higher quality data could be obtained from the Si side due to the enhanced contrast between the weak diamagnetic scattering and the nuclear scattering from the films. A large number of interference fringes from the waves reflected from the front and back surfaces of the film could be observed, attesting to the high quality and flatness of the sample. The vacuum-Nb interface had a surface roughness of ??3.4 nm, while the Nb-Si interface was nearly atomically smooth. We also carried out an experiment on a 300 nm-thick film of YBa2Cu3O7, but the roughness was so severe that no interference fringes could be observed, and reliable measurements of ? could not be obtained. The magnetic screening length for the Nb films was measured to be ?=110±2 nm for the sample with an electron mean free path l=10 nm, and ?=55±2 nm for the sample with l=35 nm. Taking into account the effects of crystalline defects and impurities, we obtain the intrinsic London penetration depth in superconducting Nb to be ?L=43±8 nm at T=4.5 K. This result is in good agreement with that of Felcher et al.

Huai Zhang; J. W. Lynn; C. F. Majkrzak; S. K. Satija; J. H. Kang; X. D. Wu

1995-10-01T23:59:59.000Z

449

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

450

August 2013 Jianbang Gan  

E-Print Network [OSTI]

and Marketing), Iowa State University, 1988 B.S., Forest Engineering, Fujian Agriculture and Forestry University Specialty: Forest Resource Economics, Management, and Policy Current Research Interests: Bioenergy

451

Touch, taste & devour: phenomenology of film and the film experiencer in the cinema of sensations.  

E-Print Network [OSTI]

??This thesis explores the possibilities of reconciling corporeal and visceral film experience with theory. It provides an analyses of two contemporary films; Marina de Van's… (more)

Aaltonen, Minna-Ella

2011-01-01T23:59:59.000Z

452

Growth and interface phase stability of barium hexaferrite films on SiC(0001)  

SciTech Connect (OSTI)

We have studied interface phase stability of the BaFe{sub 12}O{sub 19} (BaM) thin films grown by molecular beam epitaxy on SiC(0001). The films were epitaxially grown with the following crystallographic relation: BaM(0001) parallel SiC(0001) and BaM(11-20) parallel SiC(11-20). High resolution TEM reveals the existence of two interfacial bands with different structure than BaM. The first band close to SiC is SiO{sub x} while the second has spinel structure and chemically corresponds to Fe{sub 3}O{sub 4}. These findings suggest that at initial growth stages Fe{sub 3}O{sub 4} is more favorable than BaM. Density functional theory modeling of the phase stability of BaM compared to Fe{sub 3}O{sub 4} shows that BaM is only stable at high oxygen partial pressures.

Lazarov, V. K. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); York JEOL Nanoscience Centre, Heslington, York YO10 5DD (United Kingdom); Hasnip, P. J. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Cai, Z.; Ziemer, K. S. [Chemical Engineering Department, Northeastern University, Boston, Massachusetts 02115 (United States); Yoshida, K. [York JEOL Nanoscience Centre, Heslington, York YO10 5DD (United Kingdom)

2011-04-01T23:59:59.000Z

453

Temperature-dependent electrical characterization of nitrogen-doped ZnO thin film: vacuum annealing effect  

Science Journals Connector (OSTI)

Temperature-dependent Hall effect measurements were carried out at an N-doped ZnO thin film grown by the reactive sputtering method onto (001) Si substrate before and after being vacuum annealed at 900?°C. p-Type ZnO thin film was obtained with a relatively high mobility of ~60?cm2?V?1?s?1, a high carrier concentration of 2.5?1017?cm?3 and a low resistivity of 0.4???cm. After vacuum annealing, the temperature dependence of electrical parameters such as mobility and carrier concentration showed highly different characteristics. Time-resolved photoluminescence (TRPL), PL and x-ray diffraction measurements (XRD) were performed after the annealing process to check whether the high-temperature annealing can remove the ZnO film on Si or not. The PL measurement shows band-to-band recombination at 360?nm and TRPL shows the exciton recombination lifetime to be 571.7?ps. The XRD measurement reveals highly preferred c-axis (0002) orientation. Activation energies were calculated using the ln ? versus 1000?T?1 plot to be 20?meV for the as-grown and 24 and 6.8?meV after the vacuum annealing process.

Emre Gür; S Tüzemen; S Do?an

2009-01-01T23:59:59.000Z

454

Liquid soap film generates electricity  

E-Print Network [OSTI]

We have observed that a rotating liquid soap film generates electricity when placed between two non-contact electrodes with a sufficiently large potential difference. In our experiments suspended liquid film (water + soap film) is formed on the surface of a circular frame, which is forced to rotate in the $x-y$ horizontal plane by a motor. This system is located at the center of two capacitor-like vertical plates to apply an external electric voltage difference in the $x-$direction. The produced electric current is collected from the liquid film using two conducting electrodes that are separated in the $y-$direction. We previously reported that a liquid film in an external electric field rotates when an electric current passes through it, naming it the liquid film motor (LFM). In this paper we report a novel technique, in which a similar device can be used as an electric generator, converting the rotating mechanical energy to electrical energy. The liquid film electric generator (LFEG) is in stark contrast to the LFM, both of which could be designed similarly in very small scales like micro scales with different applications. Although the device is comparable to commercial electric motors or electric generators, there is a significant difference in their working principles. Usually in an electric motor or generator the magnetic field causes the driving force, while in a LFM or LFEG the Coulomb force is the driving force. This fact is also interesting from the Bio-science point of view and brings a similarity to bio motors. Here we have investigated the electrical characteristics of such a generator for the first time experimentally and modelled the phenomenon with electroconvection governing equations. A numerical simulation is performed using the local approximation for the charge-potential relation and results are in qualitative agreement with experiments.

Ahmad Amjadi; Sadegh Feiz; Reza Montazeri Namin

2014-04-24T23:59:59.000Z

455

Oxygen vacancy induced photoluminescence and ferromagnetism in SrTiO{sub 3} thin films by molecular beam epitaxy  

SciTech Connect (OSTI)

SrTiO{sub 3} thin films were epitaxially grown on (100) SrTiO{sub 3} substrates using molecular beam epitaxy. The temperature for growth of the films was optimized, which was indicated by x-ray diffraction and further confirmed by microstructural characterization. Photoluminescence spectra show that oxygen-vacancy contributes to red and blue luminescence of oxygen-deficient post-annealed films, and a red shift was observed in blue region. On the other hand, ferromagnetism in film form SrTiO{sub 3} was observed from 5 K to 400 K and could be further enhanced with decreasing oxygen plasma partial pressure in annealing processes, which might be explained by the theory involving d{sup 0} magnetism related to oxygen-vacancy. From the cooperative investigations of optical and magnetic properties, we conclude that intrinsic defects, especially oxygen-vacancy, can induce and enhance luminescence and magnetism in SrTiO{sub 3} films.

Xu, Wenfei; Yang, Jing; Bai, Wei; Tang, Kai; Zhang, Yuanyuan [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China)] [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Tang, Xiaodong [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China) [Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Rd., Shanghai 200050 (China)

2013-10-21T23:59:59.000Z

456

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

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

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

457

Thin Film Encapsulation Methods for Large Area MEMS Packaging  

E-Print Network [OSTI]

penetrated c) Windows in nitride film not clearly visiblea circular window is preferred to minimize film deflection

Mahajerin, Armon

2012-01-01T23:59:59.000Z

458

Study of structural properties of cubic InN films on GaAs(001) substrates by molecular beam epitaxy and migration enhanced epitaxy  

SciTech Connect (OSTI)

InN epitaxial films with cubic phase were grown by rf-plasma-assisted molecular beam epitaxy (RF-MBE) on GaAs(001) substrates employing two methods: migration-enhanced epitaxy (MEE) and conventional MBE technique. The films were synthesized at different growth temperatures ranging from 490 to 550 Degree-Sign C, and different In beam fluxes (BEP{sub In}) ranging from 5.9 Multiplication-Sign 10{sup -7} to 9.7 Multiplication-Sign 10{sup -7} Torr. We found the optimum conditions for the nucleation of the cubic phase of the InN using a buffer composed of several thin layers, according to reflection high-energy electron diffraction (RHEED) patterns. Crystallographic analysis by high resolution X-ray diffraction (HR-XRD) and RHEED confirmed the growth of c-InN by the two methods. We achieved with the MEE method a higher crystal quality and higher cubic phase purity. The ratio of cubic to hexagonal components in InN films was estimated from the ratio of the integrated X-ray diffraction intensities of the cubic (002) and hexagonal (1011) planes measured by X-ray reciprocal space mapping (RSM). For MEE samples, the cubic phase of InN increases employing higher In beam fluxes and higher growth temperatures. We have obtained a cubic purity phase of 96.4% for a film grown at 510 Degree-Sign C by MEE.

Casallas-Moreno, Y. L.; Perez-Caro, M.; Gallardo-Hernandez, S.; Ramirez-Lopez, M.; Martinez-Velis, I.; Lopez-Lopez, M. [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)] [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico); Escobosa-Echavarria, A. [Electric Engineering Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)] [Electric Engineering Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mexico D.F. (Mexico)

2013-06-07T23:59:59.000Z

459

The crystallographic texture of a great number of polyethylene films manufactured by the film  

E-Print Network [OSTI]

The crystallographic texture of a great number of polyethylene films manufactured by the film polymer films (fig. 1). It is essentially dedicated to polyethylene, espe- cially for packaging in polyethylene blown films J.-M. Haudin, J.-M. André, G. Bellet, B. Monasse, P. Navard �cole des Mines de Paris

Paris-Sud XI, Université de

460

Film Studies Page 143Sonoma State University 2014-2015 Catalog FILM STUDIES  

E-Print Network [OSTI]

will study a broad range of film texts and learn to appreciate a variety of aesthetic and filmmaking in Film Studies 1-4 ENGL 430 Creative Writing: Select Genres (Screenplay) 1-4 MLL 214 French Literature and Film 4 FR 201 Third Semester French 4 GER 210 Intermediate German though Film 4 LIBS 320C Bollywood 3

Ravikumar, B.

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461

Degenerate cadmium oxide films for electronic devices  

Science Journals Connector (OSTI)

Highly conducting and transparent cadmium oxide films have been deposited on Corning 7059 glass substrates by ion-beam sputtering and by spray pyrolysis. The electrical and optical properties of CdO films prep...

T. L. Chu; Shirley S. Chu