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Note: This page contains sample records for the topic "gallium arsenide gaas" 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.


1

E-Print Network 3.0 - arsenide-based ternary compounds Sample...  

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

gallium arsenide-based... separately claimed breakthroughs in solar cell production. Gallium arsenide (GaAs) and related compounds... of manufacturing compound semiconductors...

2

Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array  

E-Print Network [OSTI]

Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire, and will aid in the design and optimization of nanowire-based systems for solar energy-conversion applications, and the photoelectrochemical energy-conversion properties of GaAs nanowire arrays were evaluated in contact with one

Zhou, Chongwu

3

Deprotecting Thioacetyl-Terminated Terphenyldithiol for Assembly on Gallium Arsenide  

SciTech Connect (OSTI)

We characterize the assembly of terphenyldithiol (TPDT) on gallium arsenide (GaAs) from ethanol (EtOH) and tetrahydrofuran (THF) as a function of ammonium hydroxide (NH4OH) concentration. NH4OH facilitates the conversion of thioacetyl end groups of the TPDT precursor to thiolates in the assembly solution. The final structure of TPDT assembled on GaAs is sensitive not only to the assembly solvent but also to NH4OH concentration. In the presence of low concentrations of NH4OH (1 mM), TPDT assemblies from EtOH are oriented upright. The same assemblies are less upright when adsorption is carried out at higher NH4OH concentrations. In THF, TPDT does not adsorb significantly on GaAs at low NH4OH concentrations. The surface coverage and structural organization of these assemblies improve with increasing NH4OH concentrations, although these assemblies are never as organized as those from EtOH. The difference in the final structure of TPDT assemblies is attributed to differences in the thiolate fraction in the assembly solution at the point of substrate immersion.

Krapchetov,D.; Ma, H.; Jen, A.; Fischer, D.; Loo, Y.

2008-01-01T23:59:59.000Z

4

Analytic bond-order potential for the gallium arsenide system  

Science Journals Connector (OSTI)

An analytic, bond-order potential (BOP) is proposed and parametrized for the gallium arsenide system. The potential addresses primary (?) and secondary (?) bonding and the valence-dependent character of heteroatomic bonding, and it can be combined with an electron counting potential to address the distribution of electrons on the GaAs surface. The potential was derived from a tight-binding description of covalent bonding by retaining the first two levels of an expanded Green’s function for the ? and ? bond-order terms. Predictions using the potential were compared with independent estimates for the structures and binding energy of small clusters (dimers, trimers, and tetramers) and for various bulk lattices with coordinations varying from 4 to 12. The structure and energies of simple point defects and melting transitions were also investigated. The relative stabilities of the (001) surface reconstructions of GaAs were well predicted, especially under high-arsenic-overpressure conditions. The structural and binding energy trends of this GaAs BOP generally match experimental observations and ab initio calculations.

D. A. Murdick; X. W. Zhou; H. N. G. Wadley; D. Nguyen-Manh; R. Drautz; D. G. Pettifor

2006-01-20T23:59:59.000Z

5

Self-aligned submicron gate length gallium arsenide MESFET  

E-Print Network [OSTI]

SELF-ALIGNED SUBMICRON GATE LENGTH GALLIUM ARSENIDE MESFET A Thesis by HSIEN-CHING HUANG Submitted to the Graduate College of Texas ASSAM University in partial fulfillment of the requirement for the degree ol' MASTER OF SCIENCE May 1987... Major Subject: Electrical Engineering SELF-ALIGNED SUBMICRON GATE LENGTH GALLIUM ARSENIDE MESFET A Thesis by HSIEN-CHING HUANG Approved as to style and content by: Mark. H. Weichold (Chairman of Committee) Donald L. Parker (Member) dali L...

Huang, Hsien-Ching

2012-06-07T23:59:59.000Z

6

Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials  

DOE Patents [OSTI]

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, S.J.

1983-03-13T23:59:59.000Z

7

Outdoor Performance of a Thin-Film Gallium-Arsenide Photovoltaic Module  

SciTech Connect (OSTI)

We deployed a 855 cm2 thin-film, single-junction gallium arsenide (GaAs) photovoltaic (PV) module outdoors. Due to its fundamentally different cell technology compared to silicon (Si), the module responds differently to outdoor conditions. On average during the test, the GaAs module produced more power when its temperature was higher. We show that its maximum-power temperature coefficient, while actually negative, is several times smaller in magnitude than that of a Si module used for comparison. The positive correlation of power with temperature in GaAs is due to temperature-correlated changes in the incident spectrum. We show that a simple correction based on precipitable water vapor (PWV) brings the photocurrent temperature coefficient into agreement with that measured by other methods and predicted by theory. The low operating temperature and small temperature coefficient of GaAs give it an energy production advantage in warm weather.

Silverman, T. J.; Deceglie, M. G.; Marion, B.; Cowley, S.; Kayes, B.; Kurtz, S.

2013-06-01T23:59:59.000Z

8

E-Print Network 3.0 - arsenide- gallium instrument Sample Search...  

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

Summary: of gallium arsenide, a semiconductor, which is used in advanced optoelectronics, lasers, microwave circuits... , and solar cells. To determine material...

9

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption  

E-Print Network [OSTI]

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption flat gallium arsenide solar cell, we show that it is possible to modify the flow of light and enhance above the solar cell. The incoupling element is lossless and, thus, has the advantage that no energy

Grandidier, Jonathan

10

All-optical Wavelength Conversion in Aluminum Gallium Arsenide at Telecommunications Wavelengths.  

E-Print Network [OSTI]

??This thesis aims at both developing highly nonlinear Aluminum Gallium Arsenide waveguides(AlGaAs) and demonstrating all-optical wavelength conversion via cross-phase modulation in AlGaAs waveguides at telecommunications… (more)

Ng, Wing-Chau

2011-01-01T23:59:59.000Z

11

Fabrication of optoelectronic microwave linear and ring resonators on a gallium arsenide substrate  

E-Print Network [OSTI]

FABRICATION OF OPTOELECTRONIC MICROWAVE LINEAR AND RING RESONATORS ON A GALLIUM ARSENIDE SUBSTRATE A Thesis by CHUN-LIANG YEH Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1993 Major Subject: Electrical Engineering FABRICATION OF OPTOELECTRONIC MICROWAVE LINEAR AND RING RESONATORS ON A GALLIUM ARSENIDE SUBSTRATE A Thesis by CHUN-LIANG YEH Approved as to style and content by: Mark...

Yeh, Chun-Liang

1993-01-01T23:59:59.000Z

12

Two-photon photovoltaic effect in gallium arsenide Jeff Chiles,1  

E-Print Network [OSTI]

Two-photon photovoltaic effect in gallium arsenide Jichi Ma,1 Jeff Chiles,1 Yagya D. Sharma,2 214669); published September 4, 2014 The two-photon photovoltaic effect is demonstrated in gallium; (230.0250) Optoelectronics; (040.5350) Photovoltaic; (130.4310) Nonlinear. http://dx.doi.org/10.1364/OL

Fathpour, Sasan

13

A final report for Gallium arsenide P-I-N detectors for high-sensitivity imaging of thermal neutrons  

E-Print Network [OSTI]

This SBIR Phase I developed neutron detectors made FR-om gallium arsenide (GaAs) p-type/ intrinsic/n-type (P-I-N) diodes grown by metalorganic chemical vapor deposition (MOCVD) onto semi-insulating (S1) bulk GaAs wafers. A layer of isotonically enriched boron-10 evaporated onto the FR-ont surface serves to convert incoming neutrons into lithium ions and a 1.47 MeV alpha particle which creates electron-hole pairs that are detected by the GaAs diode. Various thicknesses of ''intrinsic'' (I) undoped GaAs were tested, as was use of a back-surface field (BSF) formed FR-om a layer of Al sub x Ga sub 1 sub - sub x As. Schottky-barrier diodes formed FR-om the same structures without the p+ GaAs top layer were tested as a comparison. After mesa etching and application of contacts, devices were tested in visible light before application of the boron coating. Internal quantum efficiency (IQE) of the best diode near the GaAs bandedge is over 90%. The lowest dark current measured is 1 x 10 sup - sup 1 sup 2 amps at -1 V o...

Vernon, S M

1999-01-01T23:59:59.000Z

14

Wet Chemical Functionalization of III–V Semiconductor Surfaces: Alkylation of Gallium Arsenide and Gallium Nitride by a Grignard Reaction Sequence  

Science Journals Connector (OSTI)

Wet Chemical Functionalization of III–V Semiconductor Surfaces: Alkylation of Gallium Arsenide and Gallium Nitride by a Grignard Reaction Sequence ... These observations are consistent with the known solubility of oxidized As species in water. ... Remote H plasma exposure was effective for removing halogens and hydrocarbons from the surfaces of both nitrides at 450 °C, but was not efficient for oxide removal. ...

Sabrina L. Peczonczyk; Jhindan Mukherjee; Azhar I. Carim; Stephen Maldonado

2012-02-28T23:59:59.000Z

15

Characteristics of trap-filled gallium arsenide photoconductive switches used in high gain pulsed power applications  

SciTech Connect (OSTI)

The electrical properties of semi-insulating (SI) Gallium Arsenide (GaAs) have been investigated for some time, particularly for its application as a substrate in microelectronics. Of late this material has found a variety of applications other than as an isolation region between devices, or the substrate of an active device. High resistivity SI GaAs is increasingly being used in charged particle detectors and photoconductive semiconductor switches (PCSS). PCSS made from these materials operating in both the linear and non-linear modes have applications such as firing sets, as drivers for lasers, and in high impedance, low current Q-switches or Pockels cells. In the non-linear mode, it has also been used in a system to generate Ultra-Wideband (UWB) High Power Microwaves (HPM). The choice of GaAs over silicon offers the advantage that its material properties allow for fast, repetitive switching action. Furthermore photoconductive switches have advantages over conventional switches such as improved jitter, better impedance matching, compact size, and in some cases, lower laser energy requirement for switching action. The rise time of the PCSS is an important parameter that affects the maximum energy transferred to the load and it depends, in addition to other parameters, on the bias or the average field across the switch. High field operation has been an important goal in PCSS research. Due to surface flashover or premature material breakdown at higher voltages, most PCSS, especially those used in high power operation, need to operate well below the inherent breakdown voltage of the material. The lifetime or the total number of switching operations before breakdown, is another important switch parameter that needs to be considered for operation at high bias conditions. A lifetime of {approximately} 10{sup 4} shots has been reported for PCSS's used in UWB-HPM generation [5], while it has exceeded 10{sup 8} shots for electro-optic drivers. Much effort is currently being channeled in the study related to improvements of these two parameters high bias operation and lifetime improvement for switches used in pulsed power applications. The contact material and profiles are another important area of study. Although these problems are being pursued through the incorporation of different contact materials and introducing doping near contacts, it is important that the switch properties and the conduction mechanism in these switches be well understood such that the basic nature of the problems can be properly addressed. In this paper the authors report on these two basic issues related to the device operation, i.e., mechanisms for increasing the hold-off characteristics through neutron irradiation, and the analysis of transport processes at varying field conditions in trap dominated SI GaAs in order to identify the breakdown mechanism during device operation. It is expected that this study would result in a better understanding of photoconductive switches, specifically those used in high power operation.

ISLAM,N.E.; SCHAMILOGLU,E.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; JOSHI,R.P.

2000-05-30T23:59:59.000Z

16

J. Phys. III Yance 7 (1997) 1495-1503 JULY 1997, PAGE 1495 Interaction of Copper with Dislocations in GaAs  

E-Print Network [OSTI]

. The interaction of copper with dislocations was studied in silicon-doped gallium arsenide by means growth or subsequent processing steps ill. In gallium arsenide, copper has two levels in the band gap solubility of Cu in GaAs at room temperature. The electrically inactive copper forms precipitates [3

Boyer, Edmond

17

Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride by metalorganic vapor-phase epitaxy  

E-Print Network [OSTI]

Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride to examine the effects of carbon tetrachloride concentration and temperature on the morphology of carbon with increasing carbon tetrachloride concentration. Step bunching and pinning was observed at a IV/III ratio

Li, Lian

18

Electrodeposition of Crystalline GaAs on Liquid Gallium Electrodes in Aqueous Electrolytes  

Science Journals Connector (OSTI)

Crystalline gallium arsenide (c-GaAs) possesses many desirable optoelectronic properties suited for solar energy conversion,(1) light and radiation detection,(2) chemical sensing,(3) lighting,(4) and high speed electronics. ... In contrast to conflicting previous reports on the electrodeposition of GaAs,(17, 18) we posit that c-GaAs(s) can be synthesized predictably through the electrodeposition of As from dissolved As2O3 specifically on a Ga(l) electrode at modest temperatures in water. ... Specifically, for any binary system composed of a solid dissolving into a liquid, the rate of dissolution of the solid into the liquid phase is given by eq 5:(60)(5)where kdiss is the dissolution rate constant, s is the surface area of the solid in contact with the liquid, V is the volume of the liquid, Csat is the solubility of the solid in the liquid, and Cdiss is the concentration of the dissolved solid in the bulk of the liquid phase. ...

Eli Fahrenkrug; Junsi Gu; Stephen Maldonado

2012-12-24T23:59:59.000Z

19

Solvent-Dependent Assembly of Terphenyl- and Quaterphenyldithiol on Gold and Gallium Arsenide  

Science Journals Connector (OSTI)

Solvent-Dependent Assembly of Terphenyl- and Quaterphenyldithiol on Gold and Gallium Arsenide ... This solvent pair was chosen because of an apparent solubility conflict:? while EtOH is the most common solvent for assembling alkylthiol and conjugated monothiol molecules,43-45 the longer n-phenyldithiols (n = 3, 4), in their thioacetyl forms (compounds 3 and 4 in Scheme 1), are poorly soluble in EtOH. ... The precipitate was filtered, washed with water, hexane, and methylene chloride, and dried overnight at 40 °C under vacuum to afford a light-yellow solid (5.90 g, 92%). 1H NMR (200 MHz, CDCl3) ? 7.65 (s, 4H), 7.55 (d, J = 8.0 Hz, 4H), 7.32 (d, J = 8.0 Hz, 4H), 2.55 (s, 6H). ...

Dmitry A. Krapchetov; Hong Ma; Alex K. Y. Jen; Daniel A. Fischer; Yueh-Lin Loo

2005-05-17T23:59:59.000Z

20

Biological monitoring of arsenic exposure of gallium arsenide- and inorganic arsenic-exposed workers by determination of inorganic arsenic and its metabolites in urine and hair  

SciTech Connect (OSTI)

In an attempt to establish a method for biological monitoring of inorganic arsenic exposure, the chemical species of arsenic were measured in the urine and hair of gallium arsenide (GaAs) plant and copper smelter workers. Determination of urinary inorganic arsenic concentration proved sensitive enough to monitor the low-level inorganic arsenic exposure of the GaAs plant workers. The urinary inorganic arsenic concentration in the copper smelter workers was far higher than that of a control group and was associated with high urinary concentrations of the inorganic arsenic metabolites, methylarsonic acid (MAA) and dimethylarsinic acid (DMAA). The results established a method for exposure level-dependent biological monitoring of inorganic arsenic exposure. Low-level exposures could be monitored only by determining urinary inorganic arsenic concentration. High-level exposures clearly produced an increased urinary inorganic arsenic concentration, with an increased sum of urinary concentrations of inorganic arsenic and its metabolites (inorganic arsenic + MAA + DMAA). The determination of urinary arsenobetaine proved to determine specifically the seafood-derived arsenic, allowing this arsenic to be distinguished clearly from the arsenic from occupational exposure. Monitoring arsenic exposure by determining the arsenic in the hair appeared to be of value only when used for environmental monitoring of arsenic contamination rather than for biological monitoring.

Yamauchi, H.; Takahashi, K.; Mashiko, M.; Yamamura, Y. (St. Marianna Univ. School of Medicine, Kawasaki (Japan))

1989-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Simple intrinsic defects in GaAs : numerical supplement.  

SciTech Connect (OSTI)

This Report presents numerical tables summarizing properties of intrinsic defects in gallium arsenide, GaAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz and O.A. von Lilienfeld, 'Simple intrinsic defects in GaAs', Modelling Simul. Mater. Sci Eng., Vol. 17, 084007 (2009), and intended for use as reference tables for a defect physics package in device models. The numerical results for density functional theory calculations of properties of simple intrinsic defects in gallium arsenide are presented.

Schultz, Peter Andrew

2012-04-01T23:59:59.000Z

22

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

23

An experiment to test the viability of a gallium-arsenide cathode in a SRF electron gun  

SciTech Connect (OSTI)

Strained gallium arsenide cathodes are used in electron guns for the production of polarized electrons. In order to have a sufficient quantum efficiency lifetime of the cathode the vacuum in the gun must be 10{sup -11} Torr or better, so that the cathode is not destroyed by ion back bombardment or through contamination with residual gases. All successful polarized guns are DC guns, because such vacuum levels can not be obtained in normal conducting RF guns. A superconductive RF gun may provide a sufficient vacuum level due to cryo-pumping of the cavity walls. We report on the progress of our experiment to test such a gun with normal GaAs-Cs crystals.

Kewisch,J.; Ben-Zvi, I.; Rao, T.; Burrill, A.; Pate, D.; Wu, Q.; Todd, R.; Wang, E.; Bluem, H.; Holmes, D.; Schultheiss, T.

2009-05-04T23:59:59.000Z

24

Gallium arsenide thermal conductivity and optical phonon relaxation times from first-principles calculations  

E-Print Network [OSTI]

In this paper, thermal conductivity of crystalline GaAs is calculated using first-principles lattice dynamics. The harmonic and cubic force constants are obtained by fitting them to the force-displacement data from density ...

Luo, Tengfei

25

CO{sub 2} laser-based dispersion interferometer utilizing orientation-patterned gallium arsenide for plasma density measurements  

SciTech Connect (OSTI)

A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma. A simple phase-extraction technique based on combining measurements from two successive pulses of the plasma has been used. The noise-equivalent line density was measured to be 1.7 × 10{sup 17} m{sup ?2} in a detection bandwidth of 950 kHz. One of the orientation-patterned crystals produced 13 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 13 W of peak power. Two crystals arranged sequentially produced 58 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 37 W of peak power.

Bamford, D. J.; Cummings, E. A.; Panasenko, D. [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States)] [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States); Fenner, D. B.; Hensley, J. M. [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States)] [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States); Boivin, R. L.; Carlstrom, T. N.; Van Zeeland, M. A. [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)] [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)

2013-09-15T23:59:59.000Z

26

Hydrogen passivation of EL2 defects and H2*-like complex formation in gallium arsenide  

Science Journals Connector (OSTI)

A complex formed by one As antisite (AsGa), one As, and two H atoms is proposed, in GaAs, which is reminiscent of the H2* defect in crystalline Si and properly accounts for the hydrogen neutralization of the EL2 deep donor activity. It is noticeably stable, in agreement with experimental results. The geometry and electronic structure of this complex present interesting connections with those of the isolated As antisite which clarify the EL2 passivation mechanism.

A. Amore Bonapasta

1995-02-15T23:59:59.000Z

27

Heat treatment of bulk gallium arsenide using a phosphosilicate glass cap  

SciTech Connect (OSTI)

n-type bulk GaAs crystals, capped with chemically vapor-deposited phosphosilicate glass, were heat treated at temperatures in the range of 600 to 950 /sup 0/C. Measurements on Schottky diodes and solar cells fabricated on the heat-treated material, after removal of a damaged surface layer, show an increase in free-carrier concentration, in minority-carrier-diffusion length, and in solar-cell short-circuit current. The observed changes are attributed to a removal of lifetime-reducing acceptorlike impurities, defects, or their complexes.

Mathur, G.; Wheaton, M.L.; Borrego, J.M.; Ghandhi, S.K.

1985-05-15T23:59:59.000Z

28

The Hall mobility measurement of Liquid Phase Epitaxy grown aluminum gallium arsenide  

E-Print Network [OSTI]

allows lasing action at or above room temperature. The utility of AI?Ga& ?As is based on the close latti&e match to GaAs over a range of Al mole fraction between zero and one(Fig. 1)IS). This is significant since heterojunctions between s...-type by occupying the site normally orc?pi& d by th& gro?p V element, ar?l acting as a donor. For the p-type of AI?Ga& ?As. %1g was used as an i&np?ri&y. Fig. 10 and Fig. 11 show I he r&'lal ionship bet wc?n th& in&p?r&I& & o???& r?t ?&n??&l t he alorr&i& weight...

Choi, Young-Shig

2012-06-07T23:59:59.000Z

29

The development of integrated chemical microsensors in GaAs  

SciTech Connect (OSTI)

Monolithic, integrated acoustic wave chemical microsensors are being developed on gallium arsenide (GaAs) substrates. With this approach, arrays of microsensors and the high frequency electronic components needed to operate them reside on a single substrate, increasing the range of detectable analytes, reducing overall system size, minimizing systematic errors, and simplifying assembly and packaging. GaAs is employed because it is both piezoelectric, a property required to produce the acoustic wave devices, and a semiconductor with a mature microelectronics fabrication technology. Many aspects of integrated GaAs chemical sensors have been investigated, including: surface acoustic wave (SAW) sensors; monolithic SAW delay line oscillators; GaAs application specific integrated circuits (ASIC) for sensor operation; a hybrid sensor array utilizing these ASICS; and the fully monolithic, integrated SAW array. Details of the design, fabrication, and performance of these devices are discussed. In addition, the ability to produce heteroepitaxial layers of GaAs and aluminum gallium arsenide (AlGaAs) makes possible micromachined membrane sensors with improved sensitivity compared to conventional SAW sensors. Micromachining techniques for fabricating flexural plate wave (FPW) and thickness shear mode (TSM) microsensors on thin GaAs membranes are presented and GaAs FPW delay line and TSM resonator performance is described.

CASALNUOVO,STEPHEN A.; ASON,GREGORY CHARLES; HELLER,EDWIN J.; HIETALA,VINCENT M.; BACA,ALBERT G.; HIETALA,S.L.

1999-11-01T23:59:59.000Z

30

Investigation of Gallium Partitioning Behavior in Aqueous Two-Phase Systems Containing Polyethylene Glycol and Ammonium Sulfate  

Science Journals Connector (OSTI)

Gallium is assumed to be an indispensable rare metal mainly because of its fast growing demand as gallium arsenide (GaAs) in integrated circuits. ... Traditional extraction methods for gallium usually are organic?water two-phase systems, which involve volatile, flammable, and explosive organic solvents, such as n-hexane, toluene, xylene, benzene, nitrobenzene and kerosene. ... (17) A temperature increase reduces the mutual solubility of the two phases and results in an increase of PEG concentration in the upper phase and of volume in the lower phase, which all make ?w1 increase. ...

Yuhuan Chen; Xiaoli Liu; Yan Lu; Xiuying Zhang

2009-04-22T23:59:59.000Z

31

Organometallic vapor-phase homoepitaxy of gallium arsenide assisted by a downstream hydrogen afterglow plasma in the growth region  

E-Print Network [OSTI]

of the trimeth- ylgallium (TMGa) for homoepitaxial GaAs. They found in direct comparison of the pure thermal-insulating) substrate is loaded into the depo- sition reactor of Fig. 1 without any chemical degreasing or polishing

Collins, George J.

32

A study of the interaction of gallium arsenide with wet chemical formulations using thermodynamic calculations and spectroscopic ellipsometry  

Science Journals Connector (OSTI)

This paper investigates the effectiveness of different wet chemical treatments and their ability to produce/regrow a thin, stable surface oxide layer on GaAs. Results from thermodynamic considerations indicate that a stable surface oxide layer, free of excess arsenic and arsenic oxides, can be achieved by properly choosing aqueous solutions targeted within the GaAs solubility range (pH  11) followed by deionized (DI) water rinsing. This is further corroborated by spectroscopic ellipsometric data that can qualitatively, but correctly, identify the thickness of the surface oxide layer after different wet chemical treatments. Specifically, samples treated with acidic solutions based on HCl, HF, and H3PO4 and diluted ammonium hydroxide solution produce a more stable surface layer that is thinner than the native oxide layer on GaAs. The results and subsequent discussion are presented in the context of an attempt at achieving a well passivated GaAs surface, free of excessive surface state defects responsible for Fermi-level pinning.

J. Price; J. Barnett; S. Raghavan; M. Keswani; R. Govindarajan

2010-01-01T23:59:59.000Z

33

E-Print Network 3.0 - americium arsenides Sample Search Results  

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

Summary: of gallium arsenide, a semiconductor, which is used in advanced optoelectronics, lasers, microwave circuits... , and solar cells. To determine material...

34

E-Print Network 3.0 - arsenide thin films Sample Search Results  

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

Engineering 14 Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride by metalorganic vapor-phase epitaxy Summary: :jap.aip.orgjap...

35

Optoelectronic simulation of GaAs solar cells with angularly selective filters  

SciTech Connect (OSTI)

We discuss the influence of angularly selective filters on thin film gallium arsenide solar cells. For this reason, the detailed balance model was refined to fit our needs with respect to Auger recombination, reflection, transmission, and realistic absorption. For calculating real systems, an approach was made to include optical effects of angularly selective filters into electron-hole dynamic equations implemented in PC1D, a one dimensional solar cell calculation tool. With this approach, we find a relative V{sub oc} increase of 5% for an idealized 100?nm GaAs cell, including Auger recombination.

Kraus, Tobias, E-mail: tobias.kraus@ise.fraunhofer.de; Höhn, Oliver; Hauser, Hubert; Bläsi, Benedikt [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg (Germany)

2014-02-07T23:59:59.000Z

36

Characterization of the Interface of Gold and Silver Nanostructures on InP and GaAs Synthesized via Galvanic Displacement  

Science Journals Connector (OSTI)

Galvanic displacement of noble metals on gallium arsenide to produce metal-GaAs junctions has been studied intermittently, starting with a report by Gol’derberg in 1971 of gold on GaAs. ... The presence of an acid is not necessary since Ga2O3 and As2O3 are somewhat water soluble (solubility of As2O3 > Ga2O3),(64, 65) although addition of 2% H2SO4(aq) resulted in greater gold deposition, particularly at the early stages of reaction (the first few minutes). ...

Sayed Y. Sayed; Brian Daly; Jillian M. Buriak

2008-07-23T23:59:59.000Z

37

GALLIUM--2000 30.1 By Deborah A. Kramer  

E-Print Network [OSTI]

the largest application for gallium, with optoelectronic devices [mostly laser diodes and light-use application for gallium, with 63% of total consumption. Optoelectronic devices accounted for 32% of domestic% of the gallium consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic

38

GALLIUM--1998 29.1 By Deborah A. Kramer  

E-Print Network [OSTI]

's) were the largest application for gallium, with optoelectronic devices [mostly laser diodes and light-use application for gallium, with 52% of total consumption. Optoelectronic devices accounted for 45% of domestic% of the gallium consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic

39

GALLIUM--1999 29.1 By Deborah A. Kramer  

E-Print Network [OSTI]

circuits (IC's) were the largest application for gallium, with optoelectronic devices [mostly laser diodes-use application for gallium, with 52% of total consumption. Optoelectronic devices accounted for 42% of domestic% of the gallium consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic

40

E-Print Network 3.0 - aluminium incorporating al-hf Sample Search...  

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

Solar Cells May See Off Silicon Summary: which involves growing alternate layers of gallium arsenide (GaAs) and aluminium arsenide (Al... be incorporated into. "If you can...

Note: This page contains sample records for the topic "gallium arsenide gaas" 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.


41

Designing Asynchronous Circuits in Gallium Arsenide  

E-Print Network [OSTI]

3.2.2 Super Buffered Fet Logic : : : : : : : : : : : : : : : : : 18 4 A New Logic Family 21 4.1 Input Stage : : : : : : : : : : : : : : : : : : : : : : : : : : : : 21 4.1.1 Inverter : : : : : : : : : : : : : : : : : : : : : : : : 34 5.2.2 Output stage : : : : : : : : : : : : : : : : : : : : : : : 36 5.2.3 Delay model and power

Martin, Alain

42

GALLIUM--2002 29.1 References that include a section mark () are found in the Internet  

E-Print Network [OSTI]

consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic devices application for gallium, with 46% of total consumption. Optoelectronic devices accounted for 42% of domestic

43

E-Print Network 3.0 - annealed gaas spectroscopic Sample Search...  

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

regular arrays of submicron GaAs dots on a silicon... . Annealing in arsine converted the gallium to GaAs, and caused the dots to develop faceted features... by an anneal in...

44

Processing Techniques for the 93 K Superconductor Ba2YCu3O7  

Science Journals Connector (OSTI)

...of either silicon or gallium arsenide field effect transistor...BaF2 also require some water to hydrolyze ith fluoride...than the normal solid solubilities. In addition, the...particularly in 930 gallium arsenide (GaAs) circuits...

D. W. MURPHY; D. W. JOHNSON JR.; S. JIN; R. E. HOWARD

1988-08-19T23:59:59.000Z

45

GALLIUM--2003 28.1 References that include a section mark () are found in the Internet  

E-Print Network [OSTI]

in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic devices (LEDs, laser diodes, photodetectors, and solar cells) and ICs. ICs and optoelectronic devices each accounted for 41) and optoelectronic devices [mostly laser diodes and light- emitting diodes (LEDs)]. Estimated crude gallium

46

Fabrication of a gated gallium arsenide heterostructure resonant tunneling diode  

E-Print Network [OSTI]

metallization process ivas required because separate potentials must be apphed to the top and base ol' the defined mesas. A potent&al is apphed to the top of the mesas to inject carriers for tunneling through the douhle barrier heterostructures A. rectifying... was a demetal/degrease cleanup process which re- moved any contamination that may have been nn the wal'er. This process ivas followed by deposition of AuGe/Ni on the ivafer's backside which ivill provide an ohmic contact after annealing. The backside...

Kinard, William Brian

1989-01-01T23:59:59.000Z

47

Photovoltaic Single-Crystalline, Thin-Film Cell Basics | Department of  

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

Single-Crystalline, Thin-Film Cell Basics Single-Crystalline, Thin-Film Cell Basics Photovoltaic Single-Crystalline, Thin-Film Cell Basics August 20, 2013 - 2:50pm Addthis Single-crystalline thin films are made from gallium arsenide (GaAs), a compound semiconductor that is a mixture of gallium and arsenic. Gallium arsenide (GaAs) is a compound semiconductor, a mixture of gallium and arsenic. Gallium is a byproduct of the smelting of other metals, notably aluminum and zinc, and it is rarer than gold. Arsenic is not rare, but it is poisonous. Gallium arsenide has been developed for use in solar cells at about the same time that it has been developed for light-emitting diodes, lasers, and other electronic devices that use light. GaAs solar cells offer several benefits: The GaAs bandgap is 1.43 eV-nearly ideal for single-junction solar

48

Photocurrent Spectroscopy of CdS/Plastic, CdS/Glass, and ZnTe/GaAs Hetero-pairs Formed with Pulsed-laser Deposition.  

E-Print Network [OSTI]

?? This dissertation presents photocurrent (PC) spectroscopy of thin-film cadmium sulfide (CdS) on plastic, CdS on glass, and zinc telluride (ZnTe) on gallium arsenide (GaAs)… (more)

Acharya, Krishna Prasad

2009-01-01T23:59:59.000Z

49

Gallium interactions with Zircaloy  

SciTech Connect (OSTI)

This study focuses on the effects of gallium ion implantation into zircaloy cladding material to investigate the effects that gallium may have in a reactor. High fluence ion implantation of Ga ions was conducted on heated Zircaloy-4 in the range of 10{sup 16}--10{sup 18} Ga ions/cm2. Surface effects were studied using SEM and electron microprobe analysis. The depth profile of Ga in the Zircaloy was characterized with Rutherford backscattering and SIMS techniques. Results indicate that the Zirc-4 is little affected up to a fluence of 10{sup 17} Ga ions/cm{sup 2}. After implantation of 10{sup 18} Ga ions/cm{sup 2}, sub-grain features on the order of 2 {micro}m were observed which may be due to intermetallic compound formation between Ga and Zr. For the highest fluence implant, Ga content in the Zirc-4 reached a saturation value of between 30 and 40 atomic %; significant enhanced diffusion was observed but gallium was not seen to concentrate at grain boundaries.

Woods, A.L. [ed.; West, M.K. [Texas A and M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

1999-01-01T23:59:59.000Z

50

Metal organic chemical vapor deposition of 111-v compounds on silicon  

DOE Patents [OSTI]

Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

Vernon, Stanley M. (Wellesley, MA)

1986-01-01T23:59:59.000Z

51

Doping of gallium nitride using disilane  

Science Journals Connector (OSTI)

Keywords: disilane, gallium nitride, metalorganic chemical vapor deposition, organometallic vapor phase epitaxy, silicon doping

A. E. Wickenden; L. B. Rowland; K. Doverspike; D. K. Gaskill; J. A. Freitas, Jr.; D. S. Simons; P. H. Chi

1995-11-01T23:59:59.000Z

52

E-Print Network 3.0 - arsenide gallium nitride Sample Search...  

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

An advanced diffusion model to identify emergent research issues: the case of optoelectronic devices Summary: instrumentation Absorption coefficients Aluminium Nitrides Aluminium...

53

Fabrication of an optically driven 10 GHz ring resonator on a gallium arsenide substrate  

E-Print Network [OSTI]

/D converters, optical detectors, dc to rf converters, and millimeter-wave or microwave generators. Photoconductors can be easily integrated with microelectronic devices as well as microwave circuits. Recently, an optically excited photoconductive switch... is the barrier height and y, is the electron affinity for the semiconductor. Current flow at a metal-semiconductor barrier is due mainly to majority carriers. The four major current transport methods are thermionic emission over the barrier, quantum...

McGregor, Douglas Scott

1989-01-01T23:59:59.000Z

54

Process development for the fabrication of monolithic optoelectronic resonators on gallium arsenide substrates  

E-Print Network [OSTI]

of greater solubility wash away. The wafers were immersed in a diluted MF312 developer snd slightly agitated. When development was completed, the wafers were rinsed with deionized (DI) water and blown dry. Hard baking in a low pressure chamber removes any... of greater solubility wash away. The wafers were immersed in a diluted MF312 developer snd slightly agitated. When development was completed, the wafers were rinsed with deionized (DI) water and blown dry. Hard baking in a low pressure chamber removes any...

Fairchild, Brock Wilson

2012-06-07T23:59:59.000Z

55

The Mechanism of Hydrogen Gas Evolution on GaAs Cathodes Elucidated by In Situ Infrared Spectroscopy  

Science Journals Connector (OSTI)

With n-type gallium arsenide, we present the first quantitative and dynamic study of hydrogen adsorption at a solid?liquid interface by in situ infrared spectroscopy in real time. ... The broadness of the signal may be accounted for in terms of interaction between As?H and water (see ref 22 for the analogous case of Si?H) and/or by the existence of distinct As?H sites at the surface. ... 55 One pH-dependent change in surface chemistry could be related to the solubility of oxidized arsenic. ...

B. H. Erné; F. Ozanam; J.-N. Chazalviel

1999-03-27T23:59:59.000Z

56

Cyclotron Resonance in Gallium  

Science Journals Connector (OSTI)

Azbel'-Kaner cyclotron resonance has been studied at 36 and 9 Gc/sec at 1.2°K in the three principal symmetry planes of gallium with the microwave currents both parallel and perpendicular to the applied magnetic field. The resonance signals were characterized by extreme complexity and high resolution (long relaxation times). Mass values are determined as a function of orientation of the magnetic field in the sample surfaces. No interpretation of the mass branches on a model Fermi surface is attempted, but some correlations with previous de Haas-van Alphen data are presented.

T. W. Moore

1968-01-15T23:59:59.000Z

57

Gallium interactions with Zircaloy  

E-Print Network [OSTI]

of weapons-grade plutonium (WGPu) in the United States is the conversion of weapons-grade plutonium into mixed-oxide (MOX) reactor fuel. MOX fuel fabricated in this way must be compatible with currently used nuclear fuel components. Since US WGPu contains... that gallium may have on zircaloy cladding during reactor operation. As a result of the reprocessing of spent fuel used in European nuclear programs, many studies have been conducted on the production and behavior of MOX fuel in traditional reactors [5...

West, Michael Keith

2012-06-07T23:59:59.000Z

58

Kinetics of GaAs Dissolution in H2O2?NH4OH?H2O Solutions  

Science Journals Connector (OSTI)

Gallium arsenide and other group III?V semiconductors have found numerous applications in the electronics industry because of such characteristics as the direct band gap and higher electron mobility, which make them more suitable than silicon in the fabrication of optoelectronic and high-frequency devices. ... For example, the solubilities of both As2O3 and As2O5 in water increase between 15 and 40 °C (Perry and Phillips, 1995), while Ga2O3 and Ga(OH)3 are insoluble in water and no data are available on the temperature dependence of their solubility at higher pH. ... Both Sheka et al. (1966) and Sidgwick (1950) confirm that gallium hydroxides are particularly soluble in NH4OH. ...

Christine Bryce; Dimitrios Berk

1996-12-04T23:59:59.000Z

59

Nuclear radiation detectors based on a matrix of ion-implanted p-i-n diodes on undoped GaAs epilayers  

SciTech Connect (OSTI)

Samples of nuclear detectors which represent matrices of p-i-n diodes were fabricated based on undoped gallium arsenide epitaxial layers by ion implantation technology. The detectors have a size of the active area of 0.4 Multiplication-Sign 0.4 and 0.9 Multiplication-Sign 0.9 cm{sup 2}. Electrical characteristics of fabricated detectors and results of measurements of fast neutrons spectra of {sup 241}Am-Be source by the recoil protons method are discussed.

Baryshnikov, F. M.; Britvich, G. I.; Chernykh, A. V.; Chernykh, S. V.; Chubenko, A. P.; Didenko, S. I.; Koltsov, G. I. [National University of Science and Technology 'MISIS', Leninskiy prospect 4, 119049 Moscow (Russian Federation); Institute for High Energy Physics, Polshhad nauki 1, 142281 Protvino (Russian Federation); National University of Science and Technology 'MISIS', Leninskiy prospect 4, 119049 Moscow (Russian Federation); P.N. Lebedev Physical Institute of the RAS, Leninskiy prospect 53, 119991 Moscow (Russian Federation); National University of Science and Technology 'MISIS', Leninskiy prospect 4, 119049 Moscow (Russian Federation)

2012-11-06T23:59:59.000Z

60

E-Print Network 3.0 - aluminium arsenide solar cells Sample Search...  

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

manufacturing technique holds Summary: arsenide chips manufactured in multilayer stacks: light sensors, high-speed transistors and solar cells... the photovoltaic cells that solar...

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


61

Evaluation of critical materials for five advanced design photovoltaic cells with an assessment of indium and gallium  

SciTech Connect (OSTI)

The objective of this study is to identify potential material supply constraints due to the large-scale deployment of five advanced photovoltaic (PV) cell designs, and to suggest strategies to reduce the impacts of these production capacity limitations and potential future material shortages. This report presents the results of the screening of the five following advanced PV cell designs: polycrystalline silicon, amorphous silicon, cadmium sulfide/copper sulfide frontwall, polycrystalline gallium arsenide MIS, and advanced concentrator-500X. Each of these five cells is screened individually assuming that they first come online in 1991, and that 25 GWe of peak capacity is online by the year 2000. A second computer screening assumes that each cell first comes online in 1991 and that each cell has 5 GWe of peak capacity by the year 2000, so that the total online cpacity for the five cells is 25 GWe. Based on a review of the preliminary basline screening results, suggestions were made for varying such parameters as the layer thickness, cell production processes, etc. The resulting PV cell characterizations were then screened again by the CMAP computer code. Earlier DOE sponsored work on the assessment of critical materials in PV cells conclusively identtified indium and gallium as warranting further investigation as to their availability. Therefore, this report includes a discussion of the future availability of gallium and indium. (WHK)

Watts, R.L.; Gurwell, W.E.; Jamieson, W.M.; Long, L.W.; Pawlewicz, W.T.; Smith, S.A.; Teeter, R.R.

1980-05-01T23:59:59.000Z

62

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

63

P-type gallium nitride  

DOE Patents [OSTI]

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

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

1997-08-12T23:59:59.000Z

64

Novel GaAs Devices  

Science Journals Connector (OSTI)

As the dimensions of GaAs devices shrink, the effective electron velocity should increase, leading to a shorter transit time and to a ballistic or near-ballistic mode of operation (see Chapter 2). At the same ...

Michael Shur

1987-01-01T23:59:59.000Z

65

Diffusion of small solutes in polymer-containing solutions  

Science Journals Connector (OSTI)

...Arsinogallane and Chemical Conversion to Gallium Arsenide ERIN K. BYRNE, LASZLO PARKANYI...yield the rn-V semiconductor gallium arsenide as a finely divided amorphous...the reaction small dusters of gallium arsenide were apparently present in solution...

KL Yam; DK Anderson; RE Buxbaum

1988-07-15T23:59:59.000Z

66

Local environment and composition of magnesium gallium layered...  

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

Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR Local environment and composition of magnesium gallium...

67

Self- and zinc diffusion in gallium antimonide  

SciTech Connect (OSTI)

The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT) [Dvorak, (2001)]. Many of the findings which will be reported here were previously published in three journal articles. Hartmut Bracht was the lead author on two articles on self-diffusion studies in GaSb [Bracht, (2001), (2000)], while this report's author was the lead author on Zn diffusion results [Nicols, (2001)]. Much of the information contained herein can be found in those articles, but a more detailed treatment is presented here.

Nicols, Samuel Piers

2002-03-26T23:59:59.000Z

68

Science and technology news Nanotechnology  

E-Print Network [OSTI]

method to make gallium arsenide solar cells May 20, 2010 by Lin Edwards Enlarge Image of a printed GaAs solar cell with a size ~10 x 10 mm2 on a glass substrate, with simple, metal grid contacts. Image light-sensitive semiconductors could make solar cells, night-vision cameras, and a range of other

Rogers, John A.

69

Home About UsContributeBookstore Advertising Subscribe for Free NOW!  

E-Print Network [OSTI]

.05As for the solar cells. The MESFET device membranes were transferred to glass substrates coated://www.semiconductor-today.com/news_items/2010/MAY/UOI_190510.htm #12;News 19 May 2010 Multi-story production of optoelectronics from Ga gallium arsenide (AlGaAs) layers on GaAs substrates using metal-organic chemical vapor deposition (MOCVD

Rogers, John A.

70

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

71

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

72

Journal of Engineering Physics and Thermophysics, VoL 71, No..5, 1998 SIMULATION OF A GALLIUM ARSENIDE RUNNING  

E-Print Network [OSTI]

and investigating HHT devices containing active elements with distributed parameters. Nowadays an active search structure of one or another configuration and a cathode section in the form of a Schottky barrier whose of Materials of Electronic Technology, Warsaw; Institute of Physics and Technology, National Academy

Harilal, S. S.

73

First principles predictions of intrinsic defects in aluminum arsenide, AlAs : numerical supplement.  

SciTech Connect (OSTI)

This Report presents numerical tables summarizing properties of intrinsic defects in aluminum arsenide, AlAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz, 'First principles predictions of intrinsic defects in Aluminum Arsenide, AlAs', Materials Research Society Symposia Proceedings 1370 (2011; SAND2011-2436C), and intended for use as reference tables for a defect physics package in device models.

Schultz, Peter Andrew

2012-04-01T23:59:59.000Z

74

Cryogenic gallium phosphide acousto-optic deflectors  

Science Journals Connector (OSTI)

We present measurements of the acoustic intensity in a gallium phosphide acousto-optic deflector for the 0.6–1.3-GHz frequency range and the 8–295-K temperature range. The data show a...

Fuss, Ian; Smart, Darryn

1991-01-01T23:59:59.000Z

75

Die Bestimmung von Kupfer- und Nickelspuren in Gallium  

Science Journals Connector (OSTI)

Nickel- und Kupferkontaminierungen in Gallium im ppm-Bereich und darunter stören empfindlich bei der Verwendung in der Halbleiterphysik. Der Chloridkomplex des Galliums in 6-n HC1 wird von einem stark basische...

H. Titze

1977-01-01T23:59:59.000Z

76

High Resolution Parameter Space from a Two Level Model on Semi-Insulating GaAs  

E-Print Network [OSTI]

Semi-insulating Gallium Arsenide (SI-GaAs) samples experimentally show, under high electric fields and even at room temperature, negative differential conductivity in N-shaped form (NNDC). Since the most consolidated model for n-GaAs, namely, "the model", proposed by E. Scholl was not capable to generate the NNDC curve for SI-GaAs, in this work we proposed an alternative model. The model proposed, "the two-valley model" is based on the minimal set of generation recombination equations for two valleys inside of the conduction band, and an equation for the drift velocity as a function of the applied electric field, that covers the physical properties of the nonlinear electrical conduction of the SI-GaAs system. The "two valley model" was capable to generate theoretically the NNDC region for the first time, and with that, we were able to build a high resolution parameter-space of the periodicity (PSP) using a Periodicity-Detection (PD) routine. In the parameter space were observed self-organized periodic structu...

da Silva, S L; de Oliveira, A G; Ribeiro, G M; da Silva, R L

2014-01-01T23:59:59.000Z

77

Method for Plutonium-Gallium Separation by Anodic Dissolution of a Solid Plutonium-Gallium Alloy  

SciTech Connect (OSTI)

Purified plutonium and gallium are efficiently recovered from a solid plutonium-gallium (Pu-Ga) alloy by using an electrorefining process. The solid Pu-Ga alloy is the cell anode, preferably placed in a moving basket within the electrolyte. As the surface of the Pu-Ga anode is depleted in plutonium by the electrotransport of the plutonium to a cathode, the temperature of the electrolyte is sufficient to liquify the surface, preferably at about 500 C, resulting in a liquid anode layer substantially comprised of gallium. The gallium drips from the liquified surface and is collected below the anode within the electrochemical cell. The transported plutonium is collected on the cathode surface and is recovered.

Miller, William E.; Tomczuk, Zygmunt

1998-12-08T23:59:59.000Z

78

Gallium nitride junction field-effect transistor  

DOE Patents [OSTI]

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

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

1999-01-01T23:59:59.000Z

79

Gallium nitride junction field-effect transistor  

DOE Patents [OSTI]

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

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

1999-02-02T23:59:59.000Z

80

Assessment of the Passivation Capabilities of Two Different Covalent Chemical Modifications on GaP(100)  

Science Journals Connector (OSTI)

With respect to toxicity, the UDA-functionalized GaP provided better passivation which was confirmed by less gallium leaching into water and saline solutions. ... Due to its promising characteristics for device fabrication, gallium arsenide (GaAs) has been extensively studied and the formation of self-assembled monolayers has been of interest. ... A general increase in the Ga/P ratio can be seen in the surfaces exposed to solutions compared to the clean surface which is attributed to the greater solubility of the phosphorus oxide (P2O5) compared to the gallium oxide (Ga2O3). ...

David Richards; Dmitry Zemlyanov; Albena Ivanisevic

2010-02-03T23:59:59.000Z

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


81

Gallium Nitride Synthesis Using Lithium Metal as a Nitrogen Fixant  

Science Journals Connector (OSTI)

This present work centers on the synthesis of white, microcrystalline gallium nitride from gallium and ammonia, using lithium to increase the solubility of nitrogen-containing species in the metal phase. ... After the acid was decanted and the product was rinsed repeatedly with water and then acetone, the resulting white powder was found to exhibit the powder X-ray diffractogram (PXRD) (Figure 2a) of crystalline gallium nitride (1). ...

Seán T. Barry; Stephen A. Ruoff; Arthur L. Ruoff

1998-08-13T23:59:59.000Z

82

Interactions of zircaloy cladding with gallium -- 1997 status  

SciTech Connect (OSTI)

A four phase program has been implemented to evaluate the effect of gallium in mixed oxide (MOX) fuel derived from weapons grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in LWR. This graded, four phase experimental program will evaluate the performance of prototypic Zircaloy cladding materials against: (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of an initial series of tests for phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement (LME), and (3) corrosion mechanical. These tests are designed to determine the corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge} 300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (in parts per million) of gallium in the MOX fuel. While continued migration of gallium into the initially formed intermetallic compound results in large stresses that can lead to distortion, this is also highly unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

Wilson, D.F.; DiStefano, J.R.; King, J.F.; Manneschmidt, E.T.; Strizak, J.P.

1997-11-01T23:59:59.000Z

83

Interactions of Zircaloy cladding with gallium: 1998 midyear status  

SciTech Connect (OSTI)

A program has been implemented to evaluate the effect of gallium in mixed-oxide (MOX) fuel derived from weapons-grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in a light-water reactor. The graded, four-phase experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of a series of tests for Phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests will determine corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge}300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Although continued migration of gallium into the initially formed intermetallic compound can result in large stresses that may lead to distortion, this was shown to be extremely unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

Wilson, D.F.; DiStefano, J.R.; Strizak, J.P.; King, J.F.; Manneschmidt, E.T.

1998-06-01T23:59:59.000Z

84

Light-Emitting Diodes on Semipolar Bulk Gallium Nitride Substrate  

Broader source: Energy.gov [DOE]

This project is producing high-efficiency semipolar light-emitting diodes (LEDs) on low-defect bulk gallium nitride (GaN) substrates.

85

High intensity x-ray source using liquid gallium target  

DOE Patents [OSTI]

A high intensity x-ray source that uses a flowing stream of liquid gallium as a target with the electron beam impinging directly on the liquid metal.

Smither, Robert K. (Hinsdale, IL); Knapp, Gordon S. (Cupertino, CA); Westbrook, Edwin M. (Chicago, IL); Forster, George A. (Westmont, IL)

1990-01-01T23:59:59.000Z

86

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide...  

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

(nanowires) in the compound gallium selenide. In short, ordered lines of structural vacancies in the material stimulate the growth of "one-dimensional" structures less than 1...

87

E-Print Network 3.0 - aluminium gallium indium Sample Search...  

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

An advanced diffusion model to identify emergent research issues: the case of optoelectronic devices Summary: Aluminium arsenides Ge-Si alloys Avalanche photodiodes Indium...

88

Formation of Hollow Gallium Nitride Spheres via Silica Sphere Templates  

Science Journals Connector (OSTI)

Formation of Hollow Gallium Nitride Spheres via Silica Sphere Templates ... To form reasonably uniform gallium oxide shells, the amounts of urea and water added to the reaction mixture were varied. ... Due to the low solubility of urea in 2-propanol, addition of a larger amount of urea than that used in this study is not desirable. ...

Chun-Neng Lin; Michael H. Huang

2008-12-30T23:59:59.000Z

89

First-Principles Determination of Ultrahigh Thermal Conductivity of Boron Arsenide: A Competitor for Diamond?  

Science Journals Connector (OSTI)

We have calculated the thermal conductivities (?) of cubic III-V boron compounds using a predictive first principles approach. Boron arsenide is found to have a remarkable room temperature ? over 2000??W?m-1?K-1; this is comparable to those in diamond and graphite, which are the highest bulk values known. We trace this behavior in boron arsenide to an interplay of certain basic vibrational properties that lie outside of the conventional guidelines in searching for high ? materials, and to relatively weak phonon-isotope scattering. We also find that cubic boron nitride and boron antimonide will have high ? with isotopic purification. This work provides new insight into the nature of thermal transport at a quantitative level and predicts a new ultrahigh ? material of potential interest for passive cooling applications.

L. Lindsay; D. A. Broido; T. L. Reinecke

2013-07-08T23:59:59.000Z

90

Inhibition of Protein Tyrosine Phosphatase by the Antitumor Agent Gallium Nitrate  

Science Journals Connector (OSTI)

...Gallium is known to bind to the iron transport protein transferrin...NSC 166828. gallium, tris(acetylacetonate). The gallium nitrate:transferrin...the binding of gallium to the iron transport protein transferrin...and incorporation into the iron storage protein ferritin...

Margareta M. Berggren; Leigh Ann Burns; Robert T. Abraham; and Garth Powis

1993-04-15T23:59:59.000Z

91

GREEN:  

Science Journals Connector (OSTI)

......toxicity, poor solubility in solvents...germanium, and gallium arsenide, as well...Gallium arsenide is a compound...elements gallium and arsenic...gallons of water every day...release indium gallium arsenide, filling...byproduct is water. Ann Christy......

Green Impact of Hardware

2011-05-01T23:59:59.000Z

92

Compatibility of ITER candidate structural materials with static gallium  

SciTech Connect (OSTI)

Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400{degrees}C, corrosion rates are {approx}4.0, 0.5, and 0.03 mm/yr for type 316 SS, Inconel 625, and Nb-5 Mo- 1 Zr alloy, respectively. The pure metals react rapidly with gallium. In contrast to findings in earlier studies, pure iron shows greater corrosion than nickel. The corrosion rates at 400{degrees}C are {ge}88 and 18 mm/yr, respectively, for Armco iron and Nickel 270. The results indicate that at temperatures up to 400{degrees}C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The solubility data for pure metals and oxygen in gallium are reviewed. The physical, chemical, and radioactive properties of gallium are also presented. The supply and availability of gallium, as well as price predictions through the year 2020, are summarized.

Luebbers, P.R.; Michaud, W.F.; Chopra, O.K.

1993-12-01T23:59:59.000Z

93

Behavior of Zircaloy Cladding in the Presence of Gallium  

SciTech Connect (OSTI)

The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional MOX fuel, on cladding material performance. An experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium, and (2) various concentrations of G~03. Three types of tests were performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests were to determine corrosion mechanisms, thresholds for temperature and concentration of gallium that delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Results have generally been favorable for the use of weapons-grade (WG) MOX fhel. The Zircaloy cladding does react with gallium to form intermetallic compounds at >3000 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Furthermore, no evidence for grain boundary penetration by gallium or liquid metal embrittlement was observed.

DiStefano, J.R.; King, J.F.; Manneschmidt, E.T.; Strizak, J.P.; Wilson, D.F.

1998-09-28T23:59:59.000Z

94

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally,  

E-Print Network [OSTI]

% of the gallium consumed was used in integrated circuits (ICs). Optoelectronic devices, which include laser diodes of the remaining gallium consumption. Optoelectronic devices were used in aerospace applications, consumer goods

95

Surface Science Analysis of GaAs Photocathodes Following Sustained...  

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

Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, strained super-lattice GaAs photocathode samples, removed from the CEBAF...

96

Role of gallium-67 in the clinical evaluation of cancer  

SciTech Connect (OSTI)

This review is based primarily on historic data, and it examines the indications for and limitations of gallium-67 scanning in the evaluation of patients with neoplasms. The use of gallium-67 scans is discussed according to tumor type, and data from the most representative and comprehensive studies are included. The results described, some of which were obtained primarily with older imaging techniques, should be regarded as representing the minimum that can be expected from application of this imaging procedure.

Bekerman, C.; Hoffer, P.B.; Bitran, J.D.

1984-10-01T23:59:59.000Z

97

It's Elemental - Isotopes of the Element Gallium  

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

Zinc Zinc Previous Element (Zinc) The Periodic Table of Elements Next Element (Germanium) Germanium Isotopes of the Element Gallium [Click for Main Data] Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information. Naturally Occurring Isotopes Mass Number Natural Abundance Half-life 69 60.108% STABLE 71 39.892% STABLE Known Isotopes Mass Number Half-life Decay Mode Branching Percentage 56 No Data Available Proton Emission (suspected) No Data Available 57 No Data Available Proton Emission (suspected) No Data Available 58 No Data Available Proton Emission (suspected) No Data Available 59 No Data Available Proton Emission (suspected) No Data Available 60 70 milliseconds Electron Capture 98.40%

98

Cavity optomechanics in gallium phosphide microdisks  

SciTech Connect (OSTI)

We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8?×?10{sup 5} and mode volumes <10(?/n){sup 3}, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0?×?10{sup 4} intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5??m and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2??30?kHz for the fundamental mechanical radial breathing mode at 488?MHz.

Mitchell, Matthew; Barclay, Paul E., E-mail: pbarclay@ucalgary.ca [Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada); Hryciw, Aaron C. [National Institute for Nanotechnology, 11421 Saskatchewan Dr. NW, Edmonton, Alberta T6G 2M9 (Canada)

2014-04-07T23:59:59.000Z

99

Gallium based low-interaction anions  

DOE Patents [OSTI]

The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

King, Wayne A. (Santa Fe, NM); Kubas, Gregory J. (Santa Fe, NM)

2000-01-01T23:59:59.000Z

100

Implantation of carbon in GaAs  

SciTech Connect (OSTI)

Carbon implanted into GaAs and thermally annealed typically exhibits very low (<3%) electrical activity. It has been demonstrated that the electrical activity of C can be significantly enhanced by co-implantation with Ga. Improved activation may result from either additional damage of the crystal lattice or from stoichiometric changes, forcing the C atoms onto As sites. To determine the relative importance of each of these effects, I have undertaken a systematic study of carbon activation in GaAs. A range of co-implants have been used: group III (B, Ga), group V (N, P, As) and noble gases (Ar, Kr). The damage introduced to the substrate will depend on the mass of the ion implanted. The group III and group V co-implants will affect the crystal stoichiometry. The results indicate that both lattice damage and crystal stoichiometry are important for high electrical activity of C. Increasing the damage will increase the activation due to the increased number of As vacancies but maximum activation can be obtained only by a co-implant which not only damages the lattice but also forces the C to occupy an As site.

Moll, A.J.

1992-03-01T23:59:59.000Z

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


101

Simulation studies on the evolution of gallium nitride on a liquid gallium surface under plasma bombardmenta)  

Science Journals Connector (OSTI)

Monte Carlo simulations were conducted to study the formation of gallium-nitride (GaN) layer on liquid gallium (Ga) sputtering target immersed in nitrogen ( N 2 ) plasma. In the simulation model N ions were assumed to possess energy equal to the bias voltage applied to the sputtering target with respect to the plasma. The results showed the surface morphology of GaN changed from a relatively smooth GaN on Ga surface at 50 eV N ion energy to a rough surface with GaN dendrites on liquid Ga at 500 eV ion energy. Further increase in N ion energy up to 1 keV resulted in smaller density of GaN dendrites on surface. Increasing surface coverage of Ga by GaN substantially reduced the sputtering yield of Ga from the target. These simulation results were correlated with previously reported experimental observations on liquid Ga surface immersed in the nitrogen plasma of a plasma-sputter-type ion source.

M. R. Vasquez Jr.; R. E. Flauta; M. Wada

2008-01-01T23:59:59.000Z

102

Photocurrent Spectroscopy of Single Wurtzite GaAs Nanowires  

SciTech Connect (OSTI)

Photocurrent of single wurtzite GaAs nanowires grown by Au-assisted molecular beam epitaxy is measured at room and low temperature (10 K). At room temperature a high photo-response with more than two orders of magnitude increase of current is observed. The wavelength dependence of the photocurrent shows a sharp change near the zinc blende GaAs band gap. The absence of the free exciton peak in the low temperature photocurrent spectrum, and problems related to determining the exact position of the energy bandgap of wurtzite GaAs from the observed data are discussed.

Kim, D. C.; Ahtapodov, L.; Boe, A. B.; Moses, A. F.; Dheeraj, D. L.; Fimland, B. O.; Weman, H. [Department of Electronics and Telecommunications, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Choi, J. W.; Ji, H.; Kim, G. T. [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

2011-12-23T23:59:59.000Z

103

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers  

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

Vacancy-Induced Nanoscale Wire Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Wednesday, 21 December 2005 00:00 Low-dimensional materials have gained much attention not only because of the nonstop march toward miniaturization in the electronics industry but also for the exotic properties that are inherent in their small size. One approach for creating low-dimensional structures is to exploit the nanoscale or atomic-scale features that exist naturally in the three-dimensional (bulk) form of materials. By this means, a group from the University of Washington has demonstrated a new way of creating one-dimensional nanoscale structures (nanowires) in the compound gallium selenide. In short, ordered lines of structural vacancies in the material stimulate the growth of "one-dimensional" structures less than 1 nanometer in width.

104

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers  

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

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Low-dimensional materials have gained much attention not only because of the nonstop march toward miniaturization in the electronics industry but also for the exotic properties that are inherent in their small size. One approach for creating low-dimensional structures is to exploit the nanoscale or atomic-scale features that exist naturally in the three-dimensional (bulk) form of materials. By this means, a group from the University of Washington has demonstrated a new way of creating one-dimensional nanoscale structures (nanowires) in the compound gallium selenide. In short, ordered lines of structural vacancies in the material stimulate the growth of "one-dimensional" structures less than 1 nanometer in width.

105

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers  

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

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Low-dimensional materials have gained much attention not only because of the nonstop march toward miniaturization in the electronics industry but also for the exotic properties that are inherent in their small size. One approach for creating low-dimensional structures is to exploit the nanoscale or atomic-scale features that exist naturally in the three-dimensional (bulk) form of materials. By this means, a group from the University of Washington has demonstrated a new way of creating one-dimensional nanoscale structures (nanowires) in the compound gallium selenide. In short, ordered lines of structural vacancies in the material stimulate the growth of "one-dimensional" structures less than 1 nanometer in width.

106

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers  

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

Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Vacancy-Induced Nanoscale Wire Structure in Gallium Selenide Layers Print Low-dimensional materials have gained much attention not only because of the nonstop march toward miniaturization in the electronics industry but also for the exotic properties that are inherent in their small size. One approach for creating low-dimensional structures is to exploit the nanoscale or atomic-scale features that exist naturally in the three-dimensional (bulk) form of materials. By this means, a group from the University of Washington has demonstrated a new way of creating one-dimensional nanoscale structures (nanowires) in the compound gallium selenide. In short, ordered lines of structural vacancies in the material stimulate the growth of "one-dimensional" structures less than 1 nanometer in width.

107

Localized corrosion of GaAs surfaces and formation of porous GaAs  

SciTech Connect (OSTI)

The present work deals with pitting corrosion of p- and n-type GaAs (100). Pit growth can be electrochemically initiated on both conduction types in chloride-containing solutions and leads after extended periods of time to the formation of a porous GaAs structure. In the case of p-type material, localized corrosion is only observed if a passivating film is present on the surface, otherwise -- e.g. in acidic solutions -- the material suffers from a uniform attack (electropolishing) which is independent of the anion present. In contrast, pitting corrosion of n-type material can be triggered independent of the presence of an oxide film. This is explained in terms of the different current limiting factor for the differently doped materials (oxide film in the case of the p- and a space charge layer in the case of the n-GaAs). The porous structure was characterized by SEM, EDX and AES, and consists mainly of GaAs. From scratch experiments it is clear that the pit initiation process is strongly influenced by surface defects. For n-type material, AFM investigations show that light induced roughening of the order of several hundred nm occurs under non-passivating conditions. This nm- scale roughening however does not affect the pitting process.

Schmuki, P.; Vitus, C.M.; Isaacs, H.S. [Brookhaven National Lab., Upton, NY (United States); Fraser, J.; Graham, M.J. [National Research Council of Canada, Ottawa, ON (Canada). Inst. for Microstructural Sciences

1995-12-01T23:59:59.000Z

108

GaAs solar cells close to the thermodynamic limit  

Science Journals Connector (OSTI)

The efficiency of GaAs solar cells can be increased by applying angularly selective filters. It is shown in terms of detailed balance model, why this happens and the concept is proven...

Hoehn, Oliver; Kraus, Tobias; Bauhuis, Gerard; Schwarz, Ulrich T; Bläsi, Benedikt

109

Exciton front propagation in photoexcited GaAs quantum wells  

E-Print Network [OSTI]

We report on the study of spatiotemporal self-organization of carriers in photoexcited GaAs quantum wells. Propagating interfaces between electron-rich and hole-rich regions are seen as expanding and collapsing exciton ...

Yang, Sen

110

GALLIUM--1997 29.1 By Deborah A. Kramer  

E-Print Network [OSTI]

As is manufactured into optoelectronic devices (LED's, laser diodes, photodetectors, and solar cells) and integrated consumption. Optoelectronic devices accounted for 44% of domestic consumption, and the remaining 7% was used by imports, primarily high-purity gallium from France and low-purity material from Russia. Optoelectronic

111

Sputtering of tin and gallium-tin clusters  

SciTech Connect (OSTI)

Tin and gallium-tin clusters have been produced by 4 keV Ar{sup +} ion bombardment of polycrystalline tin and the gallium-tin eutectic alloy and analyzed by time-of-flight mass spectrometry. The sputtered neutral species were photoionized with 193 nm (6.4 eV) excimer laser light. Neutral tin clusters containing up to 10 atoms and mixed gallium-tin clusters Ga{sub (n-m)}Sn{sub m} with n {<=} 4 for the neutrals and N {<=} 3 for the sputtered ionic species have been detected. Laser power density dependent intensity measurements, relative yields, and kinetic energy distributions have been measured. The abundance distributions of the mixed clusters have been found to be nonstatistical due to significant differences in the ionization efficiencies for clusters with equal nuclearity but different number of tin atoms. The results indicate that Ga{sub 2}Sn and Ga{sub 3}Sn like the all-gallium clusters have ionization potentials below 6.4 eV. In the case of Sn{sub 5}, Sn{sub 6}, GaSn and Ga{sub (n-m)}Sn{sub m} clusters with n=2 to 4 and m>1, the authors detect species that have sufficient internal energy to be one photon ionized despite ionization potentials that are higher 6.4 eV. The tin atom signal that is detected can be attributed to photofragmentation of dimers for both sputtering from polycrystalline tin and from the gallium-tin eutectic alloy.

Lill, T.; Calaway, W.F.; Ma, Z.; Pellin, M.J.

1994-08-01T23:59:59.000Z

112

Nickel-cobalt-iron-copper sulfides and arsenides in solution-collapse breccia pipes, northwestern Arizona  

SciTech Connect (OSTI)

An extensive suite of Ni-Co-Fe-Cu sulfides and arsenides lies within the matrix of solution-collapse breccias buried deep within the plateaus of the Grand Canyon region. Ceilings over large caverns in the Redwall collapsed, brecciating the overlying sandstone and forming cylindrical breccia pipes up to 300 ft in diameter that extend vertically as much as 3,000 ft. These highly permeable breccias served as a host for the precipitation of a suite of over 100 minerals, including uraninite, sphalerite, galena and various copper phases, in addition to the Ni-Co-bearing-phase discussed here. Intricately zoned crystals of small (<1 mm), euhedral Ni-Co-Fe-As-S minerals were the first to form during the second major episode of mineralization in these pipes. Several of these phases replace minerals, such as barite and anhydrite, from the first episode. Extensive microprobe work has been done on samples from two breccia pipe mines, the Hack 2 and Orphan, which are about 50 miles apart. Mineral compositions are similar except that no copper is found in the Ni-Co-Fe phases from the Hack 2 mine, while pyrites containing 1 wt % Cu are common from the Orphan, which was mined for copper. In some of these pyrites', Cu is dominant and the mineral is actually villamaninite. Pyrites from both mines characteristically contain 0.5 to 3 wt % As. Metal contents in zones pyrite-bravoite-vaesite (M[sub 1]S[sub 2]) crystals at the Hack 2 mine range from Fe[sub 1] to Fe[sub .12], Ni[sub 0] to Ni[sub .86], and Co[sub 0] to Co[sub .10]. The metal content for polydymite-siegenite-violarite averages about (Ni[sub 2.33]Co[sub .39]Fe[sub .23])(S[sub 3.9]As[sub .1]). Orphan mine pyrite-bravoite-vaesite-villamaninite ranges in composition from pure FeS[sub 2] to (Ni[sub .6]Fe[sub .21]Co[sub .17])S[sub 2], and (Cu[sub .46]Ni[sub .27]Fe[sub .21]Co[sub .13])S[sub 2]. Of all the sulfides or arsenides found in these breccia pipes, only nickeline consistently occurs as the pure end member.

Wenrich, K.J. (Geological Survey, Denver, CO (United States)); Hlava, P.F. (Sandia National Labs., Albuquerque, NM (United States))

1993-04-01T23:59:59.000Z

113

Preparation Of Copper Indium Gallium Diselenide Films For Solar Cells  

DOE Patents [OSTI]

High quality thin films of copper-indium-gallium-diselenide useful in the production of solar cells are prepared by electrodepositing at least one of the constituent metals onto a glass/Mo substrate, followed by physical vapor deposition of copper and selenium or indium and selenium to adjust the final stoichiometry of the thin film to approximately Cu(In,Ga)Se.sub.2. Using an AC voltage of 1-100 KHz in combination with a DC voltage for electrodeposition improves the morphology and growth rate of the deposited thin film. An electrodeposition solution comprising at least in part an organic solvent may be used in conjunction with an increased cathodic potential to increase the gallium content of the electrodeposited thin film.

Bhattacharya, Raghu N. (Littleton, CO); Contreras, Miguel A. (Golden, CO); Keane, James (Lakewood, CO); Tennant, Andrew L. (Denver, CO), Tuttle, John R. (Denver, CO); Ramanathan, Kannan (Lakewood, CO); Noufi, Rommel (Golden, CO)

1998-08-08T23:59:59.000Z

114

Neutron detection using boron gallium nitride semiconductor material  

SciTech Connect (OSTI)

In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN) semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN) samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to ?-rays but poor sensitivity to ?-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after ?-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

Atsumi, Katsuhiro [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Inoue, Yoku; Nakano, Takayuki, E-mail: ttnakan@ipc.shizuoka.ac.jp [Department of Electrical and Materials Science, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Mimura, Hidenori; Aoki, Toru [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011 (Japan)

2014-03-01T23:59:59.000Z

115

The Russian-American Gallium solar neutrino Experiment  

SciTech Connect (OSTI)

The Russian-American Gallium solar neutrino Experiment (SAGE) is described. The solar neutrino flux measured by 31 extractions through October, 1993 is presented. The result of 69 {+-} 10{sub {minus}7}{sup +5} SNU is to be compared with a standard solar model prediction of 132 SNU. The status of a {sup 51}Cr neutrino source irradiation to test the overall operation of the experiment is also presented.

Elliott, S.R. [Univ. of Washington, Seattle, WA (United States); Abdurashitov, J.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research; Bowles, T.J. [Los Alamos National Lab., NM (United States)] [and others

1995-12-31T23:59:59.000Z

116

The Russian-American gallium solar neutrino experiment  

SciTech Connect (OSTI)

The Russian-American Gallium solar neutrino Experiment (SAGE) is described. The solar neutrino flux measured by 31 extractions through October, 1993 is presented. The result of 69 {+-} 10{sub {minus}7}{sup +5} SNU is to be compared with a standard solar model prediction of 132 SNU. The status of a {sup 51}Cr neutrino source irradiation to test the overall operation of the experiment is also presented.

Elliott, S.R.; Wilkerson, J.F. [Univ. of Washington, Seattle, WA (United States); Abdurashitov, J.N. [Russian Academy of Sciences, Moscow (Russian Federation). Institute of Nuclear Research] [and others

1995-08-01T23:59:59.000Z

117

Operating experience with a GaAs photoemission electron source  

SciTech Connect (OSTI)

We report on the development of several operating procedures that promise to make GaAs photoemission electron sources easier to construct, more reliable to operate, and more amenable to use in dynamic vacuum systems. We describe in particular a method for ''ohmically'' heating a <100> crystal of GaAs under vacuum to approximately 600 /sup 0/C. We also discuss our observations of the role of oxygen in the activation of the crystal surface, the use of continuous cesiation, and of the performance of the crystal under varying vacuum conditions.

Tang, F.C.; Lubell, M.S.; Rubin, K.; Vasilakis, A.; Eminyan, M.; Slevin, J.

1986-12-01T23:59:59.000Z

118

The influence of framework-gallium in zeolites: Electronegativity and infrared spectroscopic study  

SciTech Connect (OSTI)

Based on the influence of the composition (Si/Al and Si/Ga ratio) on the framework vibrations of zeolites with different structure types (FAU, LTL, BETA, MOR, MEL, MFI, TON, and MTW), an electronegativity value for gallium substituted into zeolite frameworks is proposed (Sanderson electronegativity scale). The present electronegativity value agrees with the known physicochemical properties of gallium substituted zeolites.

Dompas, D.H.; Mortier, W.J. (Katholieke Univ. Leuven (Belgium)); Kenter, O.C.H. (Delft Univ. of Technology (The Netherlands)); Janssen, M.J.G.; Verduijn, J.P. (Exxon Chemical Holland, Rotterdam (The Netherlands))

1991-05-01T23:59:59.000Z

119

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells  

E-Print Network [OSTI]

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A. Rockettb , M. Edoffa , L. Stolta a A°ngstro¨m Solar Center, Uppsala University, P.O. Box 534, SE-751 21 Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been

Rockett, Angus

120

Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics  

E-Print Network [OSTI]

Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics A. V penetration of gallium into an aluminum film. These composite films form mirrorlike interfaces with silica optics and active plasmonics. The material is a polycrystalline aluminum film on a silica sub- strate

Zheludev, Nikolay

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


121

Synthesis and use of (polyfluoroaryl)fluoroanions of aluminum, gallium and indium  

DOE Patents [OSTI]

Salts of (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are described. The (polyfluoroaryl)fluoroanions have the formula [ER'R"R'"F].sup..crclbar. wherein E is aluminum, gallium, or indium, wherein F is fluorine, and wherein R', R", and R'" is each a fluorinated phenyl, fluorinated biphenyl, or fluorinated polycyclic group.

Marks, Tobin J. (Evanston, IL); Chen, You-Xian (Midland, MI)

2000-01-01T23:59:59.000Z

122

Response of GaAs to fast intense laser pulses  

E-Print Network [OSTI]

Motivated by recent experiments, we have performed simulations which show in detail how the electrons and ions in GaAs respond to fast intense laser pulses (with durations of order 100 fs and intensities of order 1-10 TW/cm(2)). The method of tight...

Graves, JS; Allen, Roland E.

1998-01-01T23:59:59.000Z

123

High-quality InP on GaAs  

E-Print Network [OSTI]

In addition to traditional telecommunication applications, devices based on InP have received increased attention for high-performance electronics. InP growth on GaAs is motivated by the fact that InP wafers are smaller, ...

Quitoriano, Nathaniel Joseph

2006-01-01T23:59:59.000Z

124

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

E-Print Network [OSTI]

of the Nitrides of Aluminum and Gallium," J. Electrochem.1) 24 (1962). G. Long and L. M. Foster, "Aluminum Nitride, aRefractory for Aluminum to 2000°C," J. Am. Ceram. Soc. ,

Tao, Jonathan Huai-Tse

2010-01-01T23:59:59.000Z

125

Monolithic integration of GaAs and h~~~~Ga~.~Aslasers by molecular epitaxy on GaAs  

E-Print Network [OSTI]

where the thick cladding layer below the active laser region acts as a buffer layer to-yield comparable epitaxial regrowth of Ino.aGaesAs lasers through dielectric masks between GaAs laser stripes on a GaAs substrate has been used for the -first time- to monolithically integrate these two lasers emitting near 1

126

Argonne CNM Highlight: Superhydrophobicity on Silver Nanoplates  

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

Superhydrophobicity on Silver Nanoplates Superhydrophobicity on Silver Nanoplates Superhydrophobic silver nanoplates Representations of water droplets on a GaAs substrate covered with the Ag nanoplates; as featured on back cover of the journal issue Gallium arsenide wafers decorated with silver nanoplates result in composite surfaces of varying hydrophobocity. CNM researchers and collaborators at Clemson have accomplished this in part by coating the silver nanoplates with self-assembled monolayers of alkyl thiol molecules. By carefully controlling reaction conditions, the size, thickness, and surface roughness of the individual silver nanoplates are tuned to produce different topographic structures and roughness of the composite surfaces. This in turn influences the surface hydrophobicity. The composite surfaces

127

Double dielectric passivation layer on InAs  

E-Print Network [OSTI]

-integration and fabrication difficulties of Josephson junctions appear to be insurmountable in the near future. This led to an increased interest in gallium arsenide (GaAs) devices like the high-electron mobility transistor (HEMT) and the modulation-doped field effect..., the thermodynamic stabilities of the A 0 and B 0 oxides, and the mutual solubilities of the oxides are of importance [10). Unfortunately neither the diffusion rates of the elements through the oxide nor the mutual solubilities of the oxides are known...

Egley, James Lee

2012-06-07T23:59:59.000Z

128

Water-Soluble Complexes from Random Copolymer and Oppositely Charged Surfactant. 2. Complexes of Poly(ethylene glycol)-Based Cationic Random Copolymer and Bile Salts  

Science Journals Connector (OSTI)

Water-Soluble Complexes from Random Copolymer and Oppositely Charged Surfactant. 2. Complexes of Poly(ethylene glycol)-Based Cationic Random Copolymer and Bile Salts ... Measurements of light scattering intensity were performed at room temperature (22 °C) on a multiangle light scattering detector (DAWN EOS fitted with a Wyatt QELS correlator (Wyatt Technology Corp.)), having a 30 mW (GaAs, gallium arsenide) laser emitting vertically polarized light at wavelength ? = 690 nm. ... Turbidimetric titration was used to determine the solubility of the polymer?surfactant complexes of various compositions. ...

C. K. Nisha; Sunkara V. Manorama; Jayachandran N. Kizhakkedathu; Souvik Maiti

2004-08-28T23:59:59.000Z

129

Water-Soluble Complexes from Random Copolymer and Oppositely Charged Surfactant. 1. Complexes of Poly(ethylene glycol)-Based Cationic Random Copolymer and Sodium Dodecyl Sulfate  

Science Journals Connector (OSTI)

Water-Soluble Complexes from Random Copolymer and Oppositely Charged Surfactant. 1. Complexes of Poly(ethylene glycol)-Based Cationic Random Copolymer and Sodium Dodecyl Sulfate ... Preliminary studies on the solubility of the complexes by turbidity measurements with one of the most studied anionic surfactants, sodium dodecyl sulfate (SDS), demonstrate that complexes of the polymer with 68 mol % PEG content are insoluble in water. ... (angles are measured with respect to the direction of the laser beam) equipped with a 30 mW (GaAs, gallium arsenide) laser emitting vertically polarized light at wavelength ? = 690 nm. ...

C. K. Nisha; Pratyay Basak; Sunkara V. Manorama; Souvik Maiti; Kizhakkedathu N. Jayachandran

2003-02-26T23:59:59.000Z

130

Fabrication of Semiconductors by Wet Chemical Etch  

E-Print Network [OSTI]

Arsenide. New York: John Wiley & Sons, Inc, 1994. CONCLUSIONS AND FUTURE WORK A selective wet etch process to re- move GaAs epitaxial cap layers from underlying InGaP layers has been de- veloped using a solution of H2SO4: H2O2:deionized water at a rate... the computing and electronics industries. Semiconducting materials, such as silicon, germanium, gallium ar- senide, and indium phosphide, are neither good insulators nor good con- ductors, but they have intrinsic electri- cal properties so that by controlled...

Francoviglia, Laura

2008-07-01T23:59:59.000Z

131

Microsoft PowerPoint - Gallium Oxide_Ramana  

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

Gallium Oxide Nanostructures Gallium Oxide Nanostructures for High Temperature Sensors C.V. Ramana (PI) Evgeny Shafirovich (Co-PI) Mechanical Engineering, University of Texas at El Paso Students: Ernesto Rubio (PhD); S.K. Samala (MS) A.K. Narayana Swamy (PhD); K. Abhilash (MS) Program Manager: Richard Dunst, NETL, DOE Project: DE-FE0007225 Project Period: 10/01/2011 to 09/31/2014 1 06/12/2013 DOE UCR/HBCU Conference, June 11-13, 2013 2 ï‚· Introduction ï‚· Research Objectives ï‚· Experiments â–º Synthesis â–º Characterization ï‚· Results and Discussion â–º Pure Ga 2 O 3 Thin Films â–º W-doped Ga 2 O 3 Thin Films (Physical Methods) ï‚· Summary & Future Work 06/12/2013 DOE UCR/HBCU Conference, June 11-13, 2013 3 06/12/2013 DOE UCR/HBCU Conference, June 11-13, 2013 4 Energy Systems High-T High-T High-P High-P

132

Accurate characterization and improvement of GaAs microstrip attenuation  

E-Print Network [OSTI]

Mason Carroll, B. S. , Rose-Hulman Institute of Technology Chair of Advisory Committee: Dr. Kai Chang Microstrip transmission lines are widely used in microv, ave circuits. The high frequencies cause the microstrip characteristics, especially... OF CONTENTS . . LIST OF FIGURES LIST OF TABLES. . CHAPTER I INTRODUCTION . . I. A Introduction. I. B Thesis Research Il GaAs MICROSTRlp ATTENUATION . II. A Characterization ol'Transmission Line Attenuation. . . . II. A. I Introduction. II. A. 2...

Carroll, James Mason

2012-06-07T23:59:59.000Z

133

E-Print Network 3.0 - aluminum gallium indium Sample Search Results  

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

4F84E-A98D-4D11-B923-779B4467077F Unexpected Discovery Could Yield Full Spectrum Solar Cell Summary: elements from group III of the periodic table, like aluminum, gallium, and...

134

Polycrystalline Thin-Film Research: Copper Indium Gallium Diselenide (Fact Sheet)  

SciTech Connect (OSTI)

Capabilities fact sheet for the National Center for Photovoltaics: Polycrystalline Thin-Film Research: Copper Indium Gallium Diselenide that includes scope, core competencies and capabilities, and contact/web information.

Not Available

2011-06-01T23:59:59.000Z

135

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

136

Enhanced Performance of Small GaAs Solar Cells via Edge and Surface Passivation with Trioctylphosphine Sulfide  

E-Print Network [OSTI]

Enhanced Performance of Small GaAs Solar Cells via Edge and Surface PassivationAs solar cells. Photoluminescence (PL) measurements indicate monolayers of TOP:S on GaAs significantly" GaAs solar cell (0.31 mm2 ) to test its ability to passivate devices with the relevant dimensions

Atwater, Harry

137

Study of Magnetohydrodynamic Surface Waves on Liquid Gallium  

SciTech Connect (OSTI)

Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed.

Hantao Ji; William Fox; David Pace; H.L. Rappaport

2004-05-13T23:59:59.000Z

138

2=picosecond, GaAs photodiode optoelectronic circuit for optical correlation applications  

E-Print Network [OSTI]

2=picosecond, GaAs photodiode optoelectronic circuit for optical correlation applications K. D. Li GaAs Schottky photodiode is monolithically integrated with a microwave detector. By using this new optoelectronic circuit.in place of a nonlinear crystal in an optical correlation setup, the high-speed photodiode

Ozbay, Ekmel

139

Electro-optic imagery of high-voltage GaAs photoconductive switches  

SciTech Connect (OSTI)

The authors present electro-optic images of GaAs high-voltage photoconductive switches utilizing the electro-optic effect of the semi-insulating GaAs substrate. Experimental methodology for obtaining the images is described along with a self-calibrating data reduction algorithm. Use of the technique for observing fabrication defects is shown.

Falk, R.A.; Adams, J.C.; Capps, C.D.; Ferrier, S.G.; Krinsky, J.A. (Boeing Defense and Space Group, Seattle, WA (United States))

1995-01-01T23:59:59.000Z

140

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission  

E-Print Network [OSTI]

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission angle Emily D Kosten1 solar cell under direct sunlight, light is received from the solar disk, but is re-emitted isotropically.1038/lsa.2013.1; published online 4 January 2013 Keywords: detailed balance; GaAs solar cell; light

Atwater, Harry

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells Keisuke Nakayama,a  

E-Print Network [OSTI]

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells Keisuke Nakayama,a Katsuaki 22 September 2008 We demonstrate an improvement in efficiency of optically thin GaAs solar cells-ratio nanoparticles effectively increases the optical path of the incident light in the absorber layers resulting

Atwater, Harry

142

Free carrier induced spectral shift for GaAs filled metallic hole arrays  

E-Print Network [OSTI]

. Soref, and J. A. D. Alamo, "Carrier-induced change in refractive index of InP, GaAs, and InGaAsP," IEEE-photon absorption (3PA) assisted by strongly enhanced local fields, reduce the refractive index of GaAs in ~200-nm thick active area through band filling and free carrier absorption. Therefore, the surface plasma wave

New Mexico, University of

143

Calculated spin polarization of field-assisted GaAs electron source  

Science Journals Connector (OSTI)

Calculations are reported showing that for the field-assisted GaAs NEA photocathode, the spin polarization of emitted electrons can be 3.6 times higher than for non-field GaAs sources. The reason for this is that...

B. Yang; V. Guidi; L. Tecchio

1993-02-01T23:59:59.000Z

144

Quantum effects in electron beam pumped GaAs  

SciTech Connect (OSTI)

Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.

Yahia, M. E. [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt) [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Azzouz, I. M. [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt)] [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)] [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)

2013-08-19T23:59:59.000Z

145

Back contacted and small form factor GAAS solar cell.  

SciTech Connect (OSTI)

We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

Clews, Peggy Jane; Wanlass, Mark W. (National Renewable Energy Laboratory); Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

2010-06-01T23:59:59.000Z

146

Exciton front propagation in photoexcited GaAs quantum wells  

Science Journals Connector (OSTI)

We report on the study of spatiotemporal self-organization of carriers in photoexcited GaAs quantum wells. Propagating interfaces between electron-rich and hole-rich regions are seen as expanding and collapsing exciton rings in exciton emission patterns. The interfaces preserve their integrity during expansion, remaining as sharp as in the steady state, which indicates that the dynamics is controlled by carrier transport. The front propagation velocity is measured and compared to theoretical model. The measurements of expanding and collapsing exciton rings afford a contactless method for probing the electron and hole transport.

Sen Yang, L. V. Butov, L. S. Levitov, B. D. Simons, and A. C. Gossard

2010-03-16T23:59:59.000Z

147

By Deborah A. Kramer No gallium production was reported in the McDonnell Douglas Corp. reportedly will world producers were Australia, Germany, and  

E-Print Network [OSTI]

facility in optoelectronic devices [light-emitting diodes France from stockpiled crude gallium produced, and in 1994. Although the total quantity of gallium used in optoelectronic devices increased, its percentage

148

Solar Innovation Timeline | Department of Energy  

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

cell Photo of two researchers analyzing a thin, circular shaped film under a small light. NREL researchers develop a gallium indium phosphidegallium arsenide solar cell...

149

History | Department of Energy  

Energy Savers [EERE]

cell Photo of two researchers analyzing a thin, circular shaped film under a small light. NREL researchers develop a gallium indium phosphidegallium arsenide solar cell...

150

Alta Devices Develops World Record Setting Thin-Film Solar Cell  

Office of Energy Efficiency and Renewable Energy (EERE)

EERE supported the development of Alta Devices' thin film Gallium Arsenide photovoltaic technology that set a world record for conversion efficiency.

151

26. 1% solar cell efficiency for Ge mechanically stacked under GaAs  

SciTech Connect (OSTI)

We have processed a diffused Ge wafer into a Ge concentrator solar cell and mechanically stacked it under a GaAs cell fabricated by Varian. We measured this stack's efficiency to be 26.1% for terrestrial air mass 1.5 direct (AM1.5D) conditions at a 285 x concentration ratio. We showed that this efficiency is limited by optical absorption in the Varian GaAs cell caused by high 2--4 (10/sup 18/) cm/sup -3/ substrate doping. We used a 2 x 10/sup 17/ cm/sup -3/ doped GaAs filter to estimate the stack efficiency as 27.4%, which would be achieved with the same Varian GaAs cell formed on a lower doped substrate. We project efficiencies assuming the best properties reported for a GaAs device. This gives a 29.6% efficiency for an improved, planar Ge cell and 31.6% efficiency for a proposed point contact geometry for the Ge cell. The corresponding space (AM0) efficiencies at a 159 x concentration ratio range from the 23.4% value we measured on the stack up to 28.4% projected for the point contact Ge place under the best GaAs cell. We showed that Ge cells give higher efficiencies than Si when stacked under GaAs.

Partain, L.D.; Kuryla, M.S.; Weiss, R.E.; Ransom, R.A.; McLeod, P.S.; Fraas, L.M.; Cape, J.A.

1987-10-01T23:59:59.000Z

152

Change in the current-carrier concentration upon doping PbTe with gallium  

SciTech Connect (OSTI)

Upon doping PbTe with gallium, both high-resistivity samples with intrinsic conductivity and low-resistivity samples with electronic conductivity (n/sub e/ = 10/sup 18/ cm/sup -3/) are produced on the PbTe-GaTe section. A thorough investigation of the dependence of the thermo-emf of Pb/sub 1-x/Ga/sub x/Te on the excess Pb and Te side showed the presence of a wide region with intrinsic conductivity. The experimental data can be explained by the fact that impure gallium in PbTe has negative Hubbard energy and stabilizes the Fermi level almost at the center of the forbidden band. At high gallium concentrations, Ga/sub 2/Te/sub 3/ precipitates at first, and then GaTe precipitates as well. The lead forming in excess transforms Ga/sup 3 +/ to Ga/sup +/, which produces the electronic conductivity in the material.

Bushmarina, G.S.; Gruzinov, B.F.; Drabkin, I.A.; Lev, E.Ya.; Moizhes, B.Ya; Suprun, S.G.

1987-07-01T23:59:59.000Z

153

Efficiency enhancement in GaAs solar cells using self-assembled microspheres  

Science Journals Connector (OSTI)

In this study we develop an efficient light harvesting scheme that can enhance the efficiency of GaAs solar cells using self-assembled microspheres. Based on the scattering of the...

Chang, Te-Hung; Wu, Pei-Hsuan; Chen, Sheng-Hui; Chan, Chia-Hua; Lee, Cheng-Chung; Chen, Chii -Chang; Su, Yan-Kuin

2009-01-01T23:59:59.000Z

154

Fabrication and Electronic Investigation of GaAs nanowire/Graphene Hybrid Devices.  

E-Print Network [OSTI]

?? In the present study, a process for fabricating GaAs nanowire/graphene hybrid devices using electron beam lithography processing techniques is presented and demonstrated. Fabricated devices… (more)

Bang, Ambjørn Dahle

2014-01-01T23:59:59.000Z

155

Ambipolar spin diffusion and D'yakonov-Perel' spin relaxation in GaAs quantum wells  

E-Print Network [OSTI]

We report theoretical and experimental studies of ambipolar spin diffusion in a semiconductor. A circularly polarized laser pulse is used to excite spin-polarized carriers in a GaAs multiple quantum-well sample at 80 K. ...

Zhao, Hui; Mower, Matt; Vignale, G.

2009-03-01T23:59:59.000Z

156

E-Print Network 3.0 - activated gaas surface Sample Search Results  

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

Collection: Materials Science 8 Dissimilar and Nanomaterials for Optoelectronic Devices Summary: ) on GaAs Diluted-N-based QW Sb-based QW (GaInNAsSb) QD-based active...

157

Gallium diffusion into self-assembled InAs quantum dots grown on indium phosphide substrates  

SciTech Connect (OSTI)

The photoluminescence spectrum of small self-assembled In(Ga)As quantum dots grown on InP substrates is composed of distinct spectral lines. These lines correspond to monolayer variations in the dots smallest dimension: their heights. We use this phenomenon in order to study the diffusion of gallium atoms into the self-assembled quantum dots. We demonstrate that substantial amounts of gallium atoms diffuse from a strained GaInP layer underneath the quantum dots into the quantum dots.

Raz, T.; Shuall, N.; Bahir, G.; Ritter, D.; Gershoni, D.; Chu, S.N.G. [Department of Electrical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa 32000 (Israel); Physics Department and The Solid State Institute, Technion - Israel Institute of Technology, Technion City, Haifa 32000 (Israel); Multiplex, Inc., 5000 Hadley Rd., South Plainfield, New Jersey 07080 (United States)

2004-10-18T23:59:59.000Z

158

Electron transfer and capture dynamics in ZnSe quantum wells grown on GaAs  

SciTech Connect (OSTI)

We investigate the transfer and capture dynamics of electrons in phase coherent photorefractive ZnSe quantum wells grown on GaAs using degenerate three-beam four-wave-mixing. The measurements reveal electron capture times by the quantum well in the order of several tens of picoseconds and a transit time of approximately 5 picoseconds from the GaAs substrate through the ZnMgSe barrier.

Dongol, A.; Wagner, H. P. [Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States)

2013-12-04T23:59:59.000Z

159

Further observations on the operation of a GaAs polarized electron source  

SciTech Connect (OSTI)

We report on several important features of GaAs polarized electron source operation. Specifically we point out the beneficial effect on crystal lifetime produced by the constant low-level application of cesium from a dispenser embedded in an extraction anode. Using our experience in low-energy polarized electron-atom scattering as a reference, we also discuss the importance of frequent energy calibrations of GaAs electron beams for high-resolution investigations.

Guo, X.Q.; Crowe, D.M.; Lubell, M.S.; Tang, F.C.; Vasilakis, A. (Department of Physics, The City College of CUNY, New York, New York 10031 (USA)); Eminyan, M. (Laboratoire de Physique Atomique, Tour 24, Universite Paris VII, F-75251 Paris (France)); Slevin, J. (Department of Experimental Physics, St. Patrick's College, Maynooth, County Kildare (Ireland))

1990-07-01T23:59:59.000Z

160

High-efficiency solar cell and method for fabrication  

DOE Patents [OSTI]

A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD).

Hou, Hong Q. (Albuquerque, NM); Reinhardt, Kitt C. (Albuquerque, NM)

1999-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

High-efficiency solar cell and method for fabrication  

DOE Patents [OSTI]

A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD). 4 figs.

Hou, H.Q.; Reinhardt, K.C.

1999-08-31T23:59:59.000Z

162

Plasmonic Light Trapping in an Ultrathin Photovoltaic Layer with Film-Coupled Metamaterial Structures  

E-Print Network [OSTI]

A film-coupled metamaterial structure is numerically investigated for enhancing the light absorption in an ultrathin photovoltaic layer of crystalline gallium arsenide (GaAs). The top subwavelength concave grating and the bottom metallic film could not only effectively trap light with the help of wave interference and magnetic resonance effects excited above the bandgap, but also practically serve as electrical contacts for photon-generated charge collection. The energy absorbed by the active layer is greatly enhanced in the film-coupled metamaterial structure, resulting in significant enhancement on the short-circuit current density by three times over a free-standing GaAs layer at the same thickness. The results would facilitate the development of next-generation ultrathin solar cells with lower cost and higher efficiency.

Wang, Hao

2014-01-01T23:59:59.000Z

163

Millimeter wave ferromagnetic resonance in gallium-substituted ?-iron oxide  

SciTech Connect (OSTI)

In millimeter wave frequency range, hexagonal ferrites with high uniaxial anisotropic magnetic fields are used as absorbers. These ferrites include M-type barium ferrite (BaFe{sub 12}O{sub 19}) and strontium ferrite (SrFe{sub 12}O{sub 19}), which have natural ferromagnetic resonant frequency range from 40 GHz to 60?GHz. However, the higher frequency range lacks suitable materials that support the higher frequency ferromagnetic resonance. A new series of gallium-substituted ?-iron oxides (?-Ga{sub x}Fe{sub 2?x}O{sub 3}) are synthesized which have ferromagnetic resonant frequencies appearing over the frequency range 30 GHz–150 GHz. The ?-Ga{sub x}Fe{sub 2?x}O{sub 3} is synthesized by the combination of reverse micelle and sol-gel techniques or the sol-gel method only. The particle sizes are observed to be smaller than 100 nm. In this paper, the free space magneto-optical approach has been employed to study these newly developed ?-Ga{sub x}Fe{sub 2?x}O{sub 3} particles in millimeter waves. This technique enables to obtain precise transmission spectra to determine the dielectric and magnetic properties of both isotropic and anisotropic ferrites in the millimeter wave frequency range from a single set of direct measurements. The transmittance and absorbance spectra of ?-Ga{sub x}Fe{sub 2?x}O{sub 3} are shown in this paper. Strong ferromagnetic resonances at different frequencies determined by the x parameter are found.

Chao, Liu, E-mail: liu.chao@tufts.edu; Afsar, Mohammed N. [Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States); Ohkoshi, Shin-ichi [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2014-05-07T23:59:59.000Z

164

Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires  

E-Print Network [OSTI]

Molten Gallium as a Catalyst for the Large-Scale Growth of Highly Aligned Silica Nanowires Zheng a small size (5-100 nm in diameter), high melting point metal (such as gold and iron) catalyst particle as an effective catalyst for the large-scale growth of highly aligned, closely packed silica nanowire bunches

Wang, Zhong L.

165

The influence of bond flexibility and molecular size on the chemically selective bonding of In 2 O and Ga 2 O on GaAs (001)-c(2×8)/(2×4)  

Science Journals Connector (OSTI)

The surface structures formed upon deposition of In 2 O and Ga 2 O by molecular beam epitaxy onto the arsenic-rich GaAs (001)-c(2×8)/(2×4) surface have been studied using scanning tunneling microscopy and density functional theory. In 2 O initially bonds with indium atoms bonding to second layer gallium atoms within the trough and proceeds to insert into or between first layer arsenic dimer pairs. In contrast Ga 2 O only inserts into or between arsenic dimer pairs due to chemical site constraints. The calculated energy needed to bend a Ga 2 O molecule approximately 70° so that it can fit into an arsenic dimer pair is 0.6 eV less than that required for In 2 O . The greater flexibility of the Ga 2 O molecule causes its insertion site to be 0.77 eV more exothermic than the In 2 O insertion site. This result shows that although trends in the periodic table can be used to predict some surface reactions small changes in atomic size can play a significant role in the chemistry of gas/surface reactions through the indirect effects of bond angle flexibility and bond length stiffness.

M. J. Hale; J. Z. Sexton; D. L. Winn; A. C. Kummel; M. Erbudak; M. Passlack

2004-01-01T23:59:59.000Z

166

This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE JOURNAL OF PHOTOVOLTAICS 1  

E-Print Network [OSTI]

as presented, with the exception of pagination. IEEE JOURNAL OF PHOTOVOLTAICS 1 Gallium Arsenide Solar Cell--Gallium arsenide, nanospheres, photovoltaic systems, whispering gallery modes (WGMs). I. INTRODUCTION THE route as the active layer is thinned [2]. Thin-film photovoltaics offer the possibility to significantly reduce

Atwater, Harry

167

GaAs Blocked-Impurity-Band Detectors for Far-Infrared Astronomy  

SciTech Connect (OSTI)

High-purity and doped GaAs films have been grown by Liquid-phase epitaxy (LPE) for development of a blocked impurity band (BIB) detector for far-infrared radiation. The film growth process developed has resulted in the capability to grow GaAs with a net active impurity concentration below 1 x 10{sup 13} cm{sup -3}, ideal for the blocking layer of the BIB detector. The growth of n-type LPE GaAs films with donor concentrations below the metal-insulator transition, as required for the absorbing layer of a BIB detector, has been achieved. The control of the donor concentration, however, was found to be insufficient for detector production. The growth by LPE of a high-purity film onto a commercially grown vapor-phase epitaxial (VPE) n-type GaAs doped absorbing layer resulted in a BIB device that showed a significant reduction in the low-temperature dark current compared to the absorbing layer only. Extended optical response was not detected, most likely due to the high compensation of the commercially grown GaAs absorbing layer, which restricts the depletion width of the device.

Cardozo, Benjamin Lewin

2004-12-21T23:59:59.000Z

168

Metal-insulator-semiconductor structures on p-type GaAs with low interface state density  

E-Print Network [OSTI]

Metal-insulator-semiconductor structures on p-type GaAs with low interface state density Zhi Chen properties of in situ deposited Si3N4 /Si/p-GaAs metal-insulator-semiconductor structures have been offered by a low gate leakage technology in GaAs, such as metal insulator structures, func- tional Ga

Chen, Zhi

169

Quantum wells on indium gallium arsenic compositionally graded buffers realized by molecular beam epitaxy  

E-Print Network [OSTI]

For a long time, there has been a desire to extend the emission wavelength of GaAs-based quantum well lasers, with the aim of eventually replacing InP with GaAs as the substrate of choice for communication applications. ...

Choy, Henry Kwong Hin, 1974-

2005-01-01T23:59:59.000Z

170

Disilane: A new silicon doping source in metalorganic chemical vapor deposition of GaAs  

Science Journals Connector (OSTI)

Disilane (Si2H6) is presented as a new silicon doping source in the metalorganic chemical vapor deposition of GaAs together with comparison results obtained using the conventional silane (SiH4) doping source. The dopingcharacteristics of disilane were studied over a wide range of growth conditions: temperature gas phase stoichiometry and disilane concentration in the growth ambient. Silicon incorporation by means of disilane pyrolysis showed no temperature dependence in sharp contrast to the strong temperature activated dependence found when employing silane. The decomposition reaction of disilane proved to be very efficient reducing the amount of dopant gas required by about two orders of magnitude at the lower growth temperatures. Electrical measurements on disilane?doped GaAs yield the same high mobilities as obtained in silane?doped GaAs films indicative of low compensation.

T. F. Kuech; B. S. Meyerson; E. Veuhoff

1984-01-01T23:59:59.000Z

171

Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs  

SciTech Connect (OSTI)

We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.

Buckley, Sonia, E-mail: bucklesm@stanford.edu; Radulaski, Marina; Vu?kovi?, Jelena [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States)] [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States); Biermann, Klaus [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)] [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

2013-11-18T23:59:59.000Z

172

Microscopic identification of the compensation mechanisms in Si-doped GaAs  

Science Journals Connector (OSTI)

The compensation mechanisms of SiGa donors in GaAs are determined by scanning tunneling microscopy. With increasing Si concentration the SiGa donors are consecutively electrically deactivated by SiAs acceptors, Si clusters, and SiGa-Ga-vacancy complexes. A microscopic model based on the screened Coulomb interaction between charged dopants, the amphoteric nature of Si, and the Fermi-level effect is proposed. It explains the observed defects, the critical Si concentrations of each identified mechanism, and predicts the solubility limit of Si in GaAs. © 1996 The American Physical Society.

C. Domke, Ph. Ebert, M. Heinrich, and K. Urban

1996-10-15T23:59:59.000Z

173

Biexciton emission from single isoelectronic traps formed by nitrogen-nitrogen pairs in GaAs  

SciTech Connect (OSTI)

We have studied photoluminescence (PL) from individual isoelectronic traps formed by nitrogen-nitrogen (NN) pairs in GaAs. Sharp emission lines due to exciton and biexciton were observed from individual isoelectronic traps in nitrogen atomic-layer doped (ALD) GaAs. The binding energy of biexciton bound to individual isoelectronic traps was approximately 8 meV. Both the exciton and biexciton luminescence lines show completely random polarization and no fine-structure splitting. These results are desirable to the application to the quantum cryptography used in the field of quantum information technology.

Takamiya, Kengo; Fukushima, Toshiyuki; Yagi, Shuhei; Hijikata, Yasuto; Yaguchi, Hiroyuki [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku , Saitama 338-8570 (Japan); Mochizuki, Toshimitsu; Yoshita, Masahiro; Akiyama, Hidefumi [Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Kuboya, Shigeyuki; Onabe, Kentaro [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Katayama, Ryuji [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2013-12-04T23:59:59.000Z

174

Formation energy of excess arsenic atoms in n-type GaAs  

Science Journals Connector (OSTI)

We report the first determination of the formation energy of excess-As-atom–related defects in Te-doped GaAs. The photocapacitance method in the constant-capacitance condition is applied to GaAs:Te prepared by 67-h annealing at 850–1100 °C under various As vapor pressures followed by rapid cooling. From an Arrhenius plot of the saturating deep-level density at quasi thermal equilibrium under high As vapor pressure, the formation energy of the defect is determined to be 1.16 eV in Te-doped horizontal-Bridgeman-grown GaAs crystals.

Jun-ichi Nishizawa; Yutaka Oyama; Kazushi Dezaki

1990-11-12T23:59:59.000Z

175

Preliminary results from the Russian-American gallium experiment Cr-neutrino source measurement  

SciTech Connect (OSTI)

The Russian-American Gallium Experiment has been collecting solar neutrino data since early 1990. The flux measurement of solar neutrinos is well below that expected from solar models. We discuss the initial results of a measurement of experimental efficiencies by exposing the gallium target to neutrinos from an artificial source. The capture rate of neutrinos from this source is very close to that which is expected. The result can be expressed as a ratio of the measured capture rate to the anticipated rate from the source activity. This ratio is 0.93 + 0.15, {minus}0.17 where the systematic and statistical errors have been combined. To first order the experimental efficiencies are in agreement with those determined during solar neutrino measurements and in previous auxiliary measurements. One must conclude that the discrepancy between the measured solar neutrino flux and that predicted by the solar models can not arise from an experimental artifact. 17 refs., 3 figs., 1 tab.

Elliott, S.R. [Washington Univ., Seattle, WA (United States); Abdurashitov, J.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. for Nuclear Research; Bowles, T.J. [Los Alamos National Lab., NM (United States)] [and others

1995-12-31T23:59:59.000Z

176

Fast neutron scattering on Gallium target at 14.8 MeV  

E-Print Network [OSTI]

Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

Han, R; Chen, Z; Nie, Y; Liu, X; Zhang, S; Ren, P; Jia, B; Tian, G; Luo, F; Lin, W; Liu, J; Shi, F; Huang, M; Ruan, X; Ren, J; Zhou, Z; Huang, H; Bao, J; Zhang, K; Hu, B

2014-01-01T23:59:59.000Z

177

Fast neutron scattering on Gallium target at 14.8 MeV  

E-Print Network [OSTI]

Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

R. Han; R. Wada; Z. Chen; Y. Nie; X. Liu; S. Zhang; P. Ren; B. Jia; G. Tian; F. Luo; W. Lin; J. Liu; F. Shi; M. Huang; X. Ruan; J. Ren; Z. Zhou; H. Huang; J. Bao; K. Zhang; B. Hu

2014-11-03T23:59:59.000Z

178

Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet  

SciTech Connect (OSTI)

Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

Murphy, R.W.

1994-12-01T23:59:59.000Z

179

Dry, laser?assisted rapid HBr etching of GaAs  

Science Journals Connector (OSTI)

Dry rapid etching of GaAs has been accomplished using an excimer laser (ArF 193 nm) with HBr etching gas by photochemical initiation. Spatially uniform etch rates of up to 8 ?m/min have been achieved on large?area masked substrates. Selective crystallographic etching is observed and controlled in the process.

P. D. Brewer; D. McClure; R. M. Osgood Jr.

1985-01-01T23:59:59.000Z

180

Dynamics of Subsurface and Surface Chemisorption for B, C, and N on Gaas and Inp  

E-Print Network [OSTI]

Using Hellmann-Feynman molecular-dynamics simulations, we have investigated interactions of first-row elements with the (110) surfaces of GaAs and InP. We find that these atoms prefer to occupy subsurface sites. The open structure...

MENON, M.; Allen, Roland E.

1991-01-01T23:59:59.000Z

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


181

Near perfect solar absorption in ultra-thin-film GaAs photonic crystals  

E-Print Network [OSTI]

Near perfect solar absorption in ultra-thin-film GaAs photonic crystals Sergey Eyderman,*a Alexei Deinegaa and Sajeev Johnab We present designs that enable a significant increase of solar absorption­99.5% solar absorption is demonstrated depending on the photonic crystal architecture used and the nature

John, Sajeev

182

GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies  

E-Print Network [OSTI]

LETTERS GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies-frequency electronics3,4 and most forms of optoelectronics5,6 . However, growing large, high quality wafers implementation. More tractable, yet still difficult, problems appear in advanced electronics and optoelectronics

Rogers, John A.

183

Non-Destructive Spent Fuel Characterization with Semi-Conducting Gallium Arsinde Neutron Imaging Arrays  

SciTech Connect (OSTI)

High resistivity bulk grown GaAs has been used to produce thermal neutron imaging devices for use in neutron radiography and characterizing burnup in spent fuel. The basic scheme utilizes a portable Sb/Be source for monoenergetic (24 keV) neutron radiation source coupled to an Fe filter with a radiation hard B-coated pixellated GaAs detector array as the primary neutron detector. The coated neutron detectors have been tested for efficiency and radiation hardness in order to determine their fitness for the harsh environments imposed by spent fuel. Theoretical and experimental results are presented, showing detector radiation hardness, expected detection efficiency and the spatial resolution from such a scheme. A variety of advanced neutron detector designs have been explored, with experimental results achieving 13% thermal neutron detection efficiency while projecting the possibility of over 30% thermal neutron detection efficiency.

Douglas S. McGregor; Holly K. Gersch; Jeffrey D. Sanders; John C. Lee; Mark D. Hammig; Michael R. Hartman; Yong Hong Yang; Raymond T. Klann; Brian Van Der Elzen; John T. Lindsay; Philip A. Simpson

2002-01-30T23:59:59.000Z

184

InGaN working electrodes with assisted bias generated from GaAs solar cells for efficient water splitting  

Science Journals Connector (OSTI)

Hydrogen generation through water splitting by n-InGaN working electrodes with bias generated from GaAs solar cell was studied. Instead of using an external bias provided by power...

Liu, Shu-Yen; Sheu, J K; Lin, Yu-Chuan; Chen, Yu-Tong; Tu, S J; Lee, M L; Lai, W C

2013-01-01T23:59:59.000Z

185

The effect of a low-energy electron beam and evaporated gold flux on GaAs surface content  

Science Journals Connector (OSTI)

This work studies changes of the GaAs surface state under the effect of low-intensity electron flux and under the effect of weakly ionized plasma (evaporated Au vapors in vacuum). It is shown that the structure a...

T. A. Bryantseva; D. V. Lyubchenko…

2012-01-01T23:59:59.000Z

186

Fabrication of wideband optoelectronic differential amplifier using a balanced receiver on a semi-insulating GaAs substrate  

E-Print Network [OSTI]

FABRICATION OF WIDEBAND OPTOELECTRONIC DIFFERENTIAL AMPLIFIER USING A BALANCED RECEIVER ON A SEMI-INSULATING GAAS SUBSTRATE A Thesis by KYOO NAM CHOI Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 1989 Major Subject: Electrical Engineering FABRICATION Ol' WIDEBAND OPTOELECTRONIC DIFFERENTIAL A1VIPLIFIER USING A BAI, ANCED RECEIVER ON A SEMI. INSULATING GAAS SUBSTRATE A Thesis by l(YOO NAM...

Choi, Kyoo Nam

1989-01-01T23:59:59.000Z

187

Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors  

SciTech Connect (OSTI)

In this study, indium-gallium-zinc-oxide thin film transistors can be operated either as transistors or resistance random access memory devices. Before the forming process, current-voltage curve transfer characteristics are observed, and resistance switching characteristics are measured after a forming process. These resistance switching characteristics exhibit two behaviors, and are dominated by different mechanisms. The mode 1 resistance switching behavior is due to oxygen vacancies, while mode 2 is dominated by the formation of an oxygen-rich layer. Furthermore, an easy approach is proposed to reduce power consumption when using these resistance random access memory devices with the amorphous indium-gallium-zinc-oxide thin film transistor.

Yang, Jyun-Bao; Chen, Yu-Ting; Chu, Ann-Kuo [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Taiwan (China); Huang, Jheng-Jie; Chen, Yu-Chun; Tseng, Hsueh-Chih [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Sze, Simon M. [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan (China)

2014-04-14T23:59:59.000Z

188

Synthesis of graphene nanoribbons from amyloid templates by gallium vapor-assisted solid-phase graphitization  

SciTech Connect (OSTI)

Single- and double-layer graphene nanoribbons (GNRs) with widths of around 10?nm were synthesized directly onto an insulating substrate by solid-phase graphitization using a gallium vapor catalyst and carbon templates made of amyloid fibrils. Subsequent investigation revealed that the crystallinity, conductivity, and carrier mobility were all improved by increasing the temperature of synthesis. The carrier mobility of the GNR synthesized at 1050?°C was 0.83 cm{sup 2}/V?s, which is lower than that of mechanically exfoliated graphene. This is considered to be most likely due to electron scattering by the defects and edges of the GNRs.

Murakami, Katsuhisa, E-mail: k.murakami@bk.tsukuba.ac.jp; Dong, Tianchen; Kajiwara, Yuya; Takahashi, Teppei; Fujita, Jun-ichi [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Hiyama, Takaki; Takai, Eisuke; Ohashi, Gai; Shiraki, Kentaro [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

2014-06-16T23:59:59.000Z

189

A near-infrared photoluminescence study of GaAs nanocrystals in SiO2 films formed by sequential ion implantation  

E-Print Network [OSTI]

A near-infrared photoluminescence study of GaAs nanocrystals in SiO2 films formed by sequential ion GaAs nanocrystals are formed in SiO2 films and several PL bands appear in the red and near-infrared spectral region. Defects and impurities in GaAs nanocrystals and SiO2 cause weak luminescence in the near-infrared

Atwater, Harry

190

Growth and properties of crystalline barium oxide on the GaAs(100) substrate  

SciTech Connect (OSTI)

Growing a crystalline oxide film on III-V semiconductor renders possible approaches to improve operation of electronics and optoelectronics heterostructures such as oxide/semiconductor junctions for transistors and window layers for solar cells. We demonstrate the growth of crystalline barium oxide (BaO) on GaAs(100) at low temperatures, even down to room temperature. Photoluminescence (PL) measurements reveal that the amount of interface defects is reduced for BaO/GaAs, compared to Al{sub 2}O{sub 3}/GaAs, suggesting that BaO is a useful buffer layer to passivate the surface of the III-V device material. PL and photoemission data show that the produced junction tolerates the post heating around 600?°C.

Yasir, M.; Dahl, J.; Lång, J.; Tuominen, M.; Punkkinen, M. P. J.; Laukkanen, P., E-mail: pekka.laukkanen@utu.fi; Kokko, K. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)] [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Kuzmin, M. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland) [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Korpijärvi, V.-M.; Polojärvi, V.; Guina, M. [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland)] [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland)

2013-11-04T23:59:59.000Z

191

Comparison of the (2×2) reconstructions of GaAs{111} surfaces  

Science Journals Connector (OSTI)

The {111} surfaces of GaAs have been examined using scanning tunneling microscopy and soft x-ray photoelectron spectroscopy and a comparison has been made between the three different (2×2) reconstructions observed. We find that both the (111)A and (111)B surfaces initially exhibit (2×2) ordered adstructures following the thermal desorption of an As cap, though spectroscopy shows them to be chemically inequivalent. With increasing temperature, the (111)A surface is found to develop into a Ga-vacancy (2×2) structure, in many ways similar to a (110) surface. The GaAs(111)B surface, however, loses its (2×2) periodicity with increasing annealing temperature, following a sequence of less As-rich structures.

J. M. C. Thornton; P. Weightman; D. A. Woolf; C. J. Dunscombe

1995-05-15T23:59:59.000Z

192

Hot-carrier cooling in GaAs: Quantum wells versus bulk  

Science Journals Connector (OSTI)

Hot-electron cooling dynamics in photoexcited bulk and quantum-well GaAs structures were determined using time-correlated single-photon counting of photoluminescence (PL) decay. Hot-electron cooling curves were generated from analyses of the time-resolved PL spectra. The time constant characterizing the hot-electron energy-loss rate, ?avg, was then determined, taking into account electron degeneracy and the time dependence of the quasi-Fermi-level. This analysis was also applied to earlier data obtained by Pelouch et al. with the same samples, but based on PL up-conversion experiments with carrier density) to bulk GaAs when this density is above a critical value. This critical density was found to range from high 1017 to low 1018 cm-3, depending upon the experimental technique; at the highest carrier densities, values of ?avg for quantum wells were found to be many hundreds of ps.

Y. Rosenwaks; M. C. Hanna; D. H. Levi; D. M. Szmyd; R. K. Ahrenkiel; A. J. Nozik

1993-11-15T23:59:59.000Z

193

(2×2) reconstructions of the {111} polar surfaces of GaAs  

Science Journals Connector (OSTI)

Ab initio total-energy calculations were used to examine (2×2) reconstruction models for the (111) and (1¯1¯1¯) surfaces of GaAs. For the (111) surface the lowest-energy Ga-vacancy geometry is determined; several mechanisms for Ga-vacancy formation are examined and other reconstructions are discussed. For the (1¯1¯1¯) surface it is shown that the As-vacancy model is unlikely and other geometries are considered.

E. Kaxiras; Y. Bar-Yam; J. D. Joannopoulos; K. C. Pandey

1986-03-15T23:59:59.000Z

194

Vacancy-Buckling Model for the (2×2) GaAs(111) Surface  

Science Journals Connector (OSTI)

A vacancy-buckling model is proposed for the (2×2) structure of the GaAs(111) surface. The model is confirmed by analysis of low-energy electron diffraction spectra. A reconstruction mechanism, basic to III-V compound surfaces, is proposed which favors equal numbers of dangling bonds on the nearest Ga and As neighbors. This model explains the (2×2) and (1×1) periodicities observed on (111) and (110) surfaces, respectively.

S. Y. Tong; G. Xu; W. N. Mei

1984-05-07T23:59:59.000Z

195

Molecular Beam Epitaxial Growth of GaAs on (631) Oriented Substrates  

SciTech Connect (OSTI)

In this work, we report the study of the homoepitaxial growth of GaAs on (631) oriented substrates by molecular beam epitaxy (MBE). We observed the spontaneous formation of a high density of large scale features on the surface. The hilly like features are elongated towards the [-5, 9, 3] direction. We show the dependence of these structures with the growth conditions and we present the possibility of to create quantum wires structures on this surface.

Cruz Hernandez, Esteban; Rojas Ramirez, Juan-Salvador; Contreras Hernandez, Rocio; Lopez Lopez, Maximo [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, Mexico D.F., 07000 (Mexico); Pulzara Mora, Alvaro [Universidad Nacional de Colombia - Sede Manizales, A. A. 127 (Colombia); Mendez Garcia, Victor H. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Seccion, C.P. 78210, San Luis Potosi (Mexico)

2007-02-09T23:59:59.000Z

196

Design and realization of a GaAs FET integrated with a heterojunction photodiode  

E-Print Network [OSTI]

1595 Design and realization of a GaAs FET integrated with a heterojunction photodiode F. Therez, M, accepté le 6 juillet 1987) Résumé. 2014 L'association d'une photodiode à hétérojonction et d'un circuit circuits intégrant l'amplificateur et la photodiode. Les divers dispositifs sont caractérisés et analysés

Paris-Sud XI, Université de

197

IMPLICATIONS OF THE INTERFACE EFFECTS IN THE NORMALLY-OFF TYPE GaAs MESFETs  

E-Print Network [OSTI]

771 IMPLICATIONS OF THE INTERFACE EFFECTS IN THE NORMALLY-OFF TYPE GaAs MESFETs G. BERT and G déserte à l'interface canal-substrat ainsi qu'à la surface de l'espace source-grille. Cette dernière, qui to the Schottky gate space-charge region both a depleted layer at the channel-substrate interface and a depleted

Boyer, Edmond

198

Raman scattering studies of the GaAs native oxide interface  

Science Journals Connector (OSTI)

Oxide filmsgrown by heat treatment on the 100 and 111 faces of GaAs have been studied by Raman backscattering. A spectrum consisting of the bulk LO and TO lines of GaAs and two additional lines labeled R1 and R2 is observed on all samples prepared at temperatures above 435° C. The additional modes are attributed to an interface region of perhaps several hundred angstroms thickness beneath the oxide film. This structure appears to be made unstable by chemical removal of the film. After the film is removed the spectrum is annealed (returns to that of GaAs) in a matter of weeks at room temperature and in about 1 h at 400° C whether the annealing atmosphere is N2 O2 or forming gas. One of the modes R2 appears to scatter as a scalar i.e. a diagonal Raman matrix element. Spectra by the R1 mode on the other hand appear to be largely unpolarized or possibly slightly nondiagonal in character. Some speculations about the possible nature of the interface region are presented.

J. A. Cape; W. E. Tennant; L. G. Hale

1977-01-01T23:59:59.000Z

199

Identification of As-vacancy complexes in Zn-diffused GaAs  

SciTech Connect (OSTI)

We have used positron annihilation spectroscopy to study the introduction of point defects in Zn-diffused semi-insulating GaAs. The diffusion was performed by annealing the samples for 2 h at 950 Degree-Sign C. The samples were etched in steps of 7 {mu}m. Both Doppler broadening using slow positron beam and lifetime spectroscopy studies were performed after each etching step. Both techniques showed the existence of vacancy-type defects in a layer of about 45 {mu}m. Secondary ion mass spectroscopy measurements illustrated the presence of Zn at high level in the sample almost up to the same depth. Vacancy-like defects as well as shallow positron traps were observed by lifetime measurements. We distinguish two kinds of defects: As vacancy belongs to defect complex, bound to most likely one Zn atom incorporated on Ga sublattice, and negative-ion-type positron traps. Zn acceptors explained the observation of shallow traps. The effect of Zn was evidenced by probing GaAs samples annealed under similar conditions but without Zn treatment. A defect-free bulk lifetime value is detected in this sample. Moreover, our positron annihilation spectroscopy measurements demonstrate that Zn diffusion in GaAs system is governed by kick-out mechanism.

Elsayed, M. [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Department of Physics, Faculty of Science, Minia University, 61519 Minia (Egypt); Krause-Rehberg, R. [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Korff, B. [Bremen Center for Computational Materials Science, University Bremen, 28359 Bremen (Germany); Richter, S. [Fraunhofer Center for Silicon Photovoltaics CSP, 06120 Halle (Saale) (Germany); Leipner, H. S. [Center of Materials Science, Martin Luther University Halle, 06099 Halle (Germany)

2013-03-07T23:59:59.000Z

200

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

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Polythiophene-based charge dissipation layer for electron beam lithography of zinc oxide and gallium nitride  

Science Journals Connector (OSTI)

The ability of thin polythiophene layers to dissipate accumulated charge in the electron beam lithography (EBL) of wide bandgap semiconductors such as zinc oxide and gallium nitride is demonstrated. A quick and inexpensive processing method is demonstrated for EBL exposure of dense and high-resolution patterns in a hydrogen silsesquioxane (HSQ) negative-tone resistdeposited on bulk ZnO samples and with GaN/AlN on sapphire substrates. For the former experimental results are given for three different cases: where no charge dissipation layer was used as well as cases where 40-nm-thick Al and 100-nm-thick conductive polymer layers were used on the top of the HSQ resist. For the latter material EBL exposure was investigated for pure HSQ and for HSQ with a thin conductive polymer layer on top. Based on the scanning electron microscope observations of the resulting photonic crystal(PhC) pattern conventional Al and the proposed polymer approach were compared. Good agreement between these results is reported while the new method considerably simplifies sample processing. Spin-coatable conducting polymer may be easily removed due to its solubility in water which makes it a perfect solution for the processing of amphoteric oxide samples i.e. zinc oxide. Gallium nitride processing also benefits from polymer dissipation layer usage due to extended exposure range and the avoidance of dense pattern overexposure in HSQ.

R. Dylewicz; S. Lis; R. M. De La Rue; F. Rahman

2010-01-01T23:59:59.000Z

202

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

203

Synthesis of Gallium Oxide Hydroxide Crystals in Aqueous Solutions with or without Urea and Their Calcination Behavior  

E-Print Network [OSTI]

solution of gallium(III) nitrate and stirring at 90°C for 10 h, followed by calcination of the recovered of solid electro- lytes of superior (as compared with Y-stabilized zirconia) ionic conductivity, i.e., La0-chemical synthesis of powders of doped LaGaO3 fuel cell ceramics.24,25 The first experimental study

Tas, A. Cuneyt

204

An assessment of the validity of cerium oxide as a surrogate for plutonium oxide gallium removal studies  

SciTech Connect (OSTI)

Methods for purifying plutonium metal have long been established. These methods use acid solutions to dissolve and concentrate the metal. However, these methods can produce significant mixed waste, that is, waste containing both radioactive and chemical hazards. The volume of waste produced from the aqueous purification of thousands of weapons would be expensive to treat and dispose. Therefore, a dry method of purification is highly desirable. Recently, a dry gallium removal research program commenced. Based on initial calculations, it appeared that a particular form of gallium (gallium suboxide, Ga{sub 2}O) could be evaporated from plutonium oxide in the presence of a reducing agent, such as small amounts of hydrogen dry gas within an inert environment. Initial tests using ceria-based material (as a surrogate for PuO{sub 2}) showed that thermally-induced gallium removal (TIGR) from small samples (on the order of one gram) was indeed viable. Because of the expense and difficulty of optimizing TIGR from plutonium dioxide, TIGR optimization tests using ceria have continued. This document details the relationship between the ceria surrogate tests and those conducted using plutonia.

Kolman, D.G.; Park, Y.; Stan, M.; Hanrahan, R.J. Jr.; Butt, D.P.

1999-03-01T23:59:59.000Z

205

Spire Semiconductor formerly Bandwidth Semiconductor LLC | Open Energy  

Open Energy Info (EERE)

Semiconductor formerly Bandwidth Semiconductor LLC Semiconductor formerly Bandwidth Semiconductor LLC Jump to: navigation, search Name Spire Semiconductor (formerly Bandwidth Semiconductor LLC) Place Hudson, New Hampshire Zip 3051 Product Spire-owned US-based manufacturer of gallium-arsenide (GaAs) cells; offers design and manufacturing capabilities of concentrator cells. References Spire Semiconductor (formerly Bandwidth Semiconductor LLC)[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Spire Semiconductor (formerly Bandwidth Semiconductor LLC) is a company located in Hudson, New Hampshire . References ↑ "Spire Semiconductor (formerly Bandwidth Semiconductor LLC)" Retrieved from "http://en.openei.org/w/index.php?title=Spire_Semiconductor_formerly_Bandwidth_Semiconductor_LLC&oldid=351621"

206

Beyond Silicon: Cutting the Costs of Solar Power | U.S. DOE Office of Science (SC)  

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

Beyond Silicon: Cutting the Costs of Solar Power Beyond Silicon: Cutting the Costs of Solar Power Stories of Discovery & Innovation Beyond Silicon: Cutting the Costs of Solar Power Enlarge Photo Courtesy of University of Illinois Mechanically flexible, high efficiency solar module that uses an interconnected array of microscale GaAs photovoltaic cells, grown in a multilayer stack on a wafer and then printed onto a sheet of plastic. Enlarge Photo 04.15.11 Beyond Silicon: Cutting the Costs of Solar Power New method of fabricating semiconductors from gallium arsenide promises more affordable solar power, improved semiconductor devices. The biggest single barrier to widespread adoption of solar power continues to be the cost of solar cells. University of Illinois materials scientists supported by the DOE Office of Science have scored a

207

X-ray induced optical reflectivity  

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

The change in optical reflectivity induced by intense x-ray pulses can now be used to study ultrafast many body responses in solids in the femtosecond time domain. X-ray absorption creates photoelectrons and core level holes subsequently filled by Auger or fluorescence processes, and these excitations ultimately add conduction and valence band carriers that perturb optical reflectivity.Optical absorption associated with band filling and band gap narrowing is shown to explain the basic features found in recent measurements on an insulator (silicon nitride, Si3N4), a semiconductor(gallium arsenide,GaAs), and a metal (gold,Au), obtained with ?100 fs x-ray pulses at 500-2000 eV and probed with 800 nm laser pulses. In particular GaAs exhibits an abrupt drop in reflectivity, persisting only for a time comparable to the x-ray excitation pulse duration, consistent with prompt band gap narrowing.

Durbin, Stephen M.

2012-01-01T23:59:59.000Z

208

Micro-cooler enhancements by barrier interface analysis  

SciTech Connect (OSTI)

A novel gallium arsenide (GaAs) based micro-cooler design, previously analysed both experimentally and by an analytical Heat Transfer (HT) model, has been simulated using a self-consistent Ensemble Monte Carlo (EMC) model for a more in depth analysis of the thermionic cooling in the device. The best fit to the experimental data was found and was used in conjunction with the HT model to estimate the cooler-contact resistance. The cooling results from EMC indicated that the cooling power of the device is highly dependent on the charge distribution across the leading interface. Alteration of this charge distribution via interface extensions on the nanometre scale has shown to produce significant changes in cooler performance.

Stephen, A.; Dunn, G. M. [Department of Physics, University of Aberdeen, King's College, AB24 3UE Aberdeen (United Kingdom)] [Department of Physics, University of Aberdeen, King's College, AB24 3UE Aberdeen (United Kingdom); Glover, J.; Oxley, C. H. [Department of Engineering, De Montfort University, Gateway, LE1 9BH Leicester (United Kingdom)] [Department of Engineering, De Montfort University, Gateway, LE1 9BH Leicester (United Kingdom); Bajo, M. Montes; Kuball, M. [Center for Device Thermography and Reliability, H. H. Wills Physics Laboratory, University of Bristol, BS8 1TL Bristol (United Kingdom)] [Center for Device Thermography and Reliability, H. H. Wills Physics Laboratory, University of Bristol, BS8 1TL Bristol (United Kingdom); Cumming, D. R. S.; Khalid, A. [School of Engineering, University of Glasgow, Rankine Building, G12 8LT Glasgow (United Kingdom)] [School of Engineering, University of Glasgow, Rankine Building, G12 8LT Glasgow (United Kingdom)

2014-02-15T23:59:59.000Z

209

Thermo-Induced Self-Assembly of Responsive Poly(DMAEMA-b-DEGMA) Block Copolymers into Multi- and Unilamellar Vesicles  

Science Journals Connector (OSTI)

LCST polymers are soluble below a certain temperature because of the formation of hydrogen bonds between water molecules of the hydration shell and the polymer chains. ... Size-exclusion chromatography (SEC) was performed on a system comprising a Waters 590 HPLC pump and a Waters 410 refractive index detector equipped with three Waters Styragel columns (HT2, HT3, HT4, each 300 mm × 7.8 mm, providing an effective molar mass range of 100–600000 g mol–1). ... High-throughput dynamic light scattering (HT-DLS) measurements were performed on the DynaPro Plate Reader Plus (Wyatt Technology Corporation, Santa Barbara, CA) equipped with a 60 mV linearly polarized gallium arsenide (GaAs) laser of ? = 832.5 nm and operating at an angle of 156°. ...

Christian Pietsch; Ulrich Mansfeld; Carlos Guerrero-Sanchez; Stephanie Hoeppener; Antje Vollrath; Michael Wagner; Richard Hoogenboom; Simon Saubern; San H. Thang; C. Remzi Becer; John Chiefari; Ulrich S. Schubert

2012-11-19T23:59:59.000Z

210

Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR spectroscopy  

SciTech Connect (OSTI)

Ordering of gallium(III) in a series of magnesium gallium layered double hydroxides (LDH’s), [Mg1-xGax(OH)2(NO3)x yH2O], was determined using solid-state 1H and 71Ga NMR spectroscopy. Depletion of Ga in these LDH’s is demonstrated to be the result of soluble [Ga(OH)4]-complexes formed during synthesis.

Petersen, Line B.; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro

2014-11-01T23:59:59.000Z

211

High-efficiency GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy  

Science Journals Connector (OSTI)

We report the initial results of GaAs and GaInP solar cells grown by all solid-state molecular- ... (MBE) technique. For GaAs single-junction solar cell, with the application of AlInP as ... back surface field la...

Shulong Lu; Lian Ji; Wei He; Pan Dai; Hui Yang…

2011-10-01T23:59:59.000Z

212

Time-evolution of the GaAs(0 0 1) pre-roughening process Z. Ding a,*, D.W. Bullock a  

E-Print Network [OSTI]

Time-evolution of the GaAs(0 0 1) pre-roughening process Z. Ding a,*, D.W. Bullock a , P.M. Thibado reserved. Keywords: Scanning tunneling microscopy; Surface roughening; Surface structure, morphology. the authors observed atomic-scale roughen- ing on GaAs(0 0 1) during growth [8]. From this, Tersoff, Johnson

Thibado, Paul M.

213

Direct determination of exact charge states of surface point defects using scanning tunneling microscopy: As vacancies on GaAs ,,110...  

E-Print Network [OSTI]

microscopy: As vacancies on GaAs ,,110... Kuo-Jen Chao, Arthur R. Smith, and Chih-Kang Shih* Department of the charge state of surface As vacancies on p-type GaAs 110 using scanning tunneling microscopy. This method utilizes the compensation between the local band bending result- ing from the As vacancy and the p

214

Imaging the p-n junction in a gallium nitride nanowire with a scanning microwave microscope  

SciTech Connect (OSTI)

We used a broadband, atomic-force-microscope-based, scanning microwave microscope (SMM) to probe the axial dependence of the charge depletion in a p-n junction within a gallium nitride nanowire (NW). SMM enables the visualization of the p-n junction location without the need to make patterned electrical contacts to the NW. Spatially resolved measurements of S{sub 11}{sup ?}, which is the derivative of the RF reflection coefficient S{sub 11} with respect to voltage, varied strongly when probing axially along the NW and across the p-n junction. The axial variation in S{sub 11}{sup ?}? effectively mapped the asymmetric depletion arising from the doping concentrations on either side of the junction. Furthermore, variation of the probe tip voltage altered the apparent extent of features associated with the p-n junction in S{sub 11}{sup ?} images.

Imtiaz, Atif [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Wallis, Thomas M.; Brubaker, Matt D.; Blanchard, Paul T.; Bertness, Kris A.; Sanford, Norman A.; Kabos, Pavel, E-mail: kabos@boulder.nist.gov [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Weber, Joel C. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Coakley, Kevin J. [Information Technology Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

2014-06-30T23:59:59.000Z

215

Origin of deep subgap states in amorphous indium gallium zinc oxide: Chemically disordered coordination of oxygen  

SciTech Connect (OSTI)

The origin of the deep subgap states in amorphous indium gallium zinc oxide (a-IGZO), whether intrinsic to the amorphous structure or not, has serious implications for the development of p-type transparent amorphous oxide semiconductors. We report that the deep subgap feature in a-IGZO originates from local variations in the oxygen coordination and not from oxygen vacancies. This is shown by the positive correlation between oxygen composition and subgap intensity as observed with X-ray photoelectron spectroscopy. We also demonstrate that the subgap feature is not intrinsic to the amorphous phase because the deep subgap feature can be removed by low-temperature annealing in a reducing environment. Atomistic calculations of a-IGZO reveal that the subgap state originates from certain oxygen environments associated with the disorder. Specifically, the subgap states originate from oxygen environments with a lower coordination number and/or a larger metal-oxygen separation.

Sallis, S.; Williams, D. S. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States); Butler, K. T.; Walsh, A. [Center for Sustainable Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Quackenbush, N. F. [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Junda, M.; Podraza, N. J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Fischer, D. A.; Woicik, J. C. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); White, B. E.; Piper, L. F. J., E-mail: lpiper@binghamton.edu [Department of Physics, Applied Physics, and Astronomy, Binghamton University, Binghamton, New York 13902 (United States); Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

2014-06-09T23:59:59.000Z

216

Catalytic and physicochemical properties of aluminoplatinum catalysts modified with indium and gallium  

SciTech Connect (OSTI)

Aluminoplatinum catalysts (APC) are widely used in transformations of hydrocarbons, particularly in reforming of gasoline fractions and dehydrogenation of higher normal paraffins. Promotion of APC with indium and gallium increases their activity and stability in the dehydrogenation of paraffins. Introduction of group III elements in APC inhibits coke formation during dehydrogenation and prevents blocking of the surface of the Pt. The change in the catalytic properties of APC modified with In is due to the partial transfer of the electron density from Pt to In. Both APC with In and Ga additives and monometallic catalysts were studied in the present article by the methods of IR spectroscopy and adsorption. In addition to traditional transmission IR spectroscopy, IR spectroscopy in diffusely scattered light was used, which permits conducting both spectral and adsorption measurements on the same samples.

Zaitsev, A.V.; Tyupaev, A.P.; Borovkov, V.Yu.; Timofeeva, E.A.; Isatulyants, G.V.; Kazanskii, B.B.

1986-10-10T23:59:59.000Z

217

Plasma Sputter-type Ion Source with Wire Electrodes for Low-energy Gallium Ion Extraction  

SciTech Connect (OSTI)

Low-energy ions of gallium (Ga) and argon (Ar) were extracted from a plasma sputter-type ion source system that utilized a tungsten (W) wire extractor geometry. The 90% transparent W wire extractor configuration had shown that the system was capable of producing an ion beam with the energy as low as 10 eV in a dc filament discharge and 50 eV in a radio frequency (rf) excited system. In the present investigation, Ar plasma was sustained in an ion source chamber through an inductively coupled 13.56 MHz rf power source. Negatively biased liquid Ga target suspended on a W reservoir was sputtered and postionized prior to extraction. Mass spectral analyses revealed a strong dependence of the Ga{sup +} current on the induced target bias.

Vasquez, M. Jr.; Kasuya, T.; Wada, M. [Graduate School of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan); Maeno, S. [Novelion Systems Co. Ltd., Kyotanabe, Kyoto 610-0332 (Japan); Miyamoto, N. [Nissin Ion Equipment Co. Ltd., Minami-ku, Kyoto 601-8205 (Japan)

2011-01-07T23:59:59.000Z

218

The status of the solar neutrino problem and the Russian-American gallium experiment (SAGE)  

SciTech Connect (OSTI)

Perhaps the most outstanding discrepancy between prediction and measurements in current particle physics comes from the solar neutrino problem, in which a large deficit of high-energy solar neutrinos is observed. Many Nonstandard Solar Models have been invoked to try to reduce the predicted flux, but all have run into problems in trying to reproduce other measured parameters (e.g., the luminosity) of the Sun. Other explanations involving new physics such as neutrino decay and neutrino oscillations, etc. have also been proffered. Again, most of these explanations have been ruled out by either laboratory or astrophysical measurements. It appears that perhaps the most likely particle physics solution is that of matter enhanced neutrino oscillation, the Mikheyev-Smirnov-Wolfenstein (MSW) oscillations. Two new radiochemical gallium experiments, which have a low enough threshold to be sensitive to the dominant flux of low-energy p-p neutrinos, now also report a deficit and also favor a particle physics solution.

Bowles, T.J.

1994-04-01T23:59:59.000Z

219

Femtosecond laser-ultrasonic investigation of plasmonic fields on the metal/gallium nitride interface  

Science Journals Connector (OSTI)

By using femtosecond laser-ultrasonic we demonstrate an approach to study the surface plasmon field optically excited in the interface between metal and a semiconductor thin film. By femtosecond impulsive excitation on gallium–nitride (GaN) different optical probe signals were observed when the impulse-excited nanoacoustic pulse propagated through the metalfilm and metal nanoslits. By analyzing the shape and temporal response of thus induced acousto-optical signals our femtosecond laser-ultrasonic study not only reveals the plasmonic field distribution optically excited in the metal/substrate interface but also confirms that the penetration depth of surface plasmon field into the substrate agrees well with a simulation result.

Hung-Pin Chen; Yu-Chieh Wen; Yi-Hsin Chen; Cheng-Hua Tsai; Kuang-Li Lee; Pei-Kuen Wei; Jinn-Kong Sheu; Chi-Kuang Sun

2010-01-01T23:59:59.000Z

220

Cryogenic growth of Al nitride on GaAs(110): X-ray-photoemission spectroscopy and inverse-photoemission spectroscopy  

Science Journals Connector (OSTI)

We report on our recent studies of Al nitride growth on GaAs(110) formed by depositing Al onto a condensed ammonia overlayer on GaAs(110) at T=90 K using x-ray-photoemission spectroscopy and inverse-photoemission spectroscopy. We have also investigated the temperature dependence of the interface thus formed. The results show some limited amount of Al nitride formed at T=90 K even though the reaction is slow, but the overlayer mostly remains metallic until the substrate is heated up. Much of the reaction of Al with ammonia occurs at about T=170 K, above which the overlayer becomes insulating. The combined information from occupied and unoccupied states reveals new features of the interface formation, and is consistent with our previous synchrotron photoemission studies of Al/NH3/GaAs(100).

Ken T. Park and Y. Gao

1993-02-15T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Vacancy-Induced 2×2 Reconstruction of the Ga(111) Surface of GaAs  

Science Journals Connector (OSTI)

Vacancy formation on the GaAs(111) surface is calculated to be strongly exothermic in character. The creation of one vacancy in each 2×2 cell allows the remaining Ga surface atoms to have a large inward relaxation, resulting in a 2.3-eV reduction in energy. It also transforms the polar (111) surface into a nonpolar (110)-like surface. The calculations provide strong support for the vacancy model of Tong et al., which is determined from analysis of low-energy-electron-diffraction data.

D. J. Chadi

1984-05-21T23:59:59.000Z

222

GaAs single quantum dot embedded into AlGaAs nanowire  

SciTech Connect (OSTI)

We report on a study of the photoluminescence spectra taken from quasi one-dimensional and quasi zero-dimensional semiconductor heterostructures. The structures were grown by molecular-beam epitaxy in (111) direction and were cylindrical nanowires based on AlGaAs, of 20 - 50 nm in diameter and 0.5 - 1 ?m in length. Inside the nanowires contain one or two GaAs quantum dots, of 2 nm thick and 15 - 45 nm in diameter. We studied a single nanowire. The photoluminescence and photoluminescence excitation spectra were registered as a function of the intensity of optical excitation.

Kochereshko, V. P.; Kats, V. N. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg, Russia and Spin Optics Laboratory, Saint Petersburg State University, Ul'yanovskaya 1, Petrodvorets, St. Petersburg, 198904 (Russian Federation); Platonov, A. V. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg (Russian Federation); Cirlin, G. E.; Bouravleuv, A. D.; Samsonenko, Yu. B. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg, Russia and St. Petersburg Academic University of the RAS Khlopina 8/3, 195220, St. Petersburg (Russian Federation); Besombes, L.; Mariette, H. [CEA-CNRS group Nanophysique et Semiconducteurs, CEA, INAC, SP2M, and Institut Néel, 17 rue des Martyrs, F-38054 Grenoble (France)

2013-12-04T23:59:59.000Z

223

Structure of negatively charged muonium in n-type GaAs  

Science Journals Connector (OSTI)

Muon level-crossing resonance and muon-spin-rotation measurements on heavily doped n-type GaAs:Si and GaAs:Te show that the majority of positive muons implanted at room temperature form an isolated diamagnetic muonium center located at a high-symmetry site with Ga neighbors along the ?111? direction(s). These experiments, together with theoretical considerations, imply that negatively charged muonium is at or near the tetrahedral interstitial site with four Ga nearest-neighbor atoms. Except for zero-point energy differences, these results should model negatively charged isolated hydrogen in GaAs.

K.H. Chow; R.F. Kiefl; W.A. MacFarlane; J.W. Schneider; D.W. Cooke; M. Leon; M. Paciotti; T.L. Estle; B. Hitti; R.L. Lichti; S.F.J. Cox; C. Schwab; E.A. Davis; A. Morrobel-Sosa; L. Zavieh

1995-05-15T23:59:59.000Z

224

Back-contacted and small form factor GaAs solar cell.  

SciTech Connect (OSTI)

We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

Clews, Peggy Jane; Wanlass, Mark W. (National Renewable Energy Laboratory, Golden, CO); Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

2010-07-01T23:59:59.000Z

225

Ultrafast magneto-photocurrents in GaAs: Separation of surface and bulk contributions  

E-Print Network [OSTI]

We induce ultrafast magneto-photocurrents in a GaAs crystal employing interband excitation with femtosecond laser pulses at room temperature and non-invasively separate surface and bulk contributions to the overall current response. The separation between the different symmetry contributions is achieved by measuring the simultaneously emitted terahertz radiation for different sample orientations. Excitation intensity and photon energy dependences of the magneto-photocurrents for linearly and circularly polarized excitations reveal an involvement of different microscopic origins, one of which we believe is the inverse Spin-Hall effect. Our experiments are important for a better understanding of the complex momentum-space carrier dynamics in magnetic fields.

Schmidt, Christian B; Tarasenko, Sergey A; Bieler, Mark

2015-01-01T23:59:59.000Z

226

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

227

Structures of the As-deficient phase on GaAs(001)-(2×4)  

Science Journals Connector (OSTI)

The atomic structures of the GaAs(001)-(2×4) surface have been studied using scanning tunneling microscopy (STM), reflectance difference spectroscopy (RDS), and reflection high-energy electron diffraction (RHEED). While STM images from the ? phase show well-ordered ?2 structures, the ? phase consists of (2×4) structures with surface As dimers locally missing from the basic ?2(2×4) units. Our RDS and RHEED analyses, together with STM observations, clearly show that the missing-dimer defect has local atomic geometry identical to the ?2(2×4) structure.

Akihiro Ohtake

2006-10-19T23:59:59.000Z

228

High excitation power photoluminescence studies of ultra-low density GaAs quantum dots  

SciTech Connect (OSTI)

We fabricate GaAs epitaxial quantum dots (QDs) by filling of self-organized nanoholes in AlGaAs. The QDs are fabricated under optimized process conditions and have ultra-low density in the 10{sup 6} cm{sup ?2} regime. At low excitation power the optical emission of single QDs exhibit sharp excitonic lines, which are attributed to the recombination of excitonic and biexcitonic states. High excitation power measurements reveal surprisingly broad emission lines from at least six QD shell states.

Sonnenberg, D.; Graf, A.; Paulava, V.; Heyn, Ch.; Hansen, W. [Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany)

2013-12-04T23:59:59.000Z

229

Coherent optical polarization of bulk GaAs studied by femtosecond photon-echo spectroscopy  

Science Journals Connector (OSTI)

The nonlinear polarization close to the band gap of GaAs is studied by spectrally and temporally resolved four-wave mixing. Excitonic and free carrier contributions both excited within the bandwidth of the 100 fs pulses are distinguished for the first time. The excitonic part dominates at carrier densities below 1016 cm-3. At higher density, nonthermalized free carriers give rise to an additional component resonant to the pulse that shows a photon-echo-like time behavior. Monte Carlo simulations including the coherent polarization and the scattering dynamics of the carriers account for the data.

A. Lohner; K. Rick; P. Leisching; A. Leitenstorfer; T. Elsaesser; T. Kuhn; F. Rossi; W. Stolz

1993-07-05T23:59:59.000Z

230

Four-photon cascade from quadexcitons in a single GaAs quantum dot  

Science Journals Connector (OSTI)

We demonstrate the generation of temporally correlated four photons emitted by the cascade recombination of a quadexciton in a self-assembled GaAs quantum dot (QD) by performing single photon correlation measurements. The cascade decay of the quadexciton involves a triexciton, a biexciton, and an exciton. The emissions of these states are identified in the photoluminescence (PL) spectrum of the QD by cross-correlation measurements. Polarization-resolved cross-correlation measurements show that the polarizations of the four photons are partly correlated. Radiative, nonradiative, and polarization flipping rates in the QD are estimated from the bunching visibilities of the cross-correlation measurements and the PL lifetimes.

Y. Arashida; Y. Ogawa; F. Minami

2011-09-12T23:59:59.000Z

231

A Single Layer of Mn in a GaAs Quantum Well: A Ferromagnet with Quantum Fluctuations  

SciTech Connect (OSTI)

Some of the highest transition temperatures achieved for Mn-doped GaAs have been in &-doped heterostructures with well-separated planes of Mn. But in the absense of magnetic anisotropy, the Mermin-Wagner theorem implies that a single plane of magnetic ions cannot be ferromagnetic. We show that the same mechanism that produces magnetic frustration and suppresses the transition can stabilize ferromagnetic order for a single layer of Mn in a GaAs quantum well. But this comes at the price of quantum fluctuations that suppress the ordered moment from that of a fully saturated ferromagnet.

Melko, Roger G [ORNL; Fishman, Randy Scott [ORNL; Reboredo, Fernando A [ORNL

2007-01-01T23:59:59.000Z

232

Gordon Research Conferences  

Science Journals Connector (OSTI)

...Polysac-charide adsorbents for ethanol-water separation." Membrane processes...boundaries in semiconduc-tors:" Gallium arsenide thin films (C. B. Duke, session...transduction." 20 August. Ion and water movements across epithelial membranes...

Alexander M. Cruickshank

1981-03-13T23:59:59.000Z

233

Spectroscopic Study of the Simultaneous Adsorption of PVP and Azelaic Acid on ?-Alumina  

Science Journals Connector (OSTI)

A 180° backscattering geometry and an indium gallium arsenide detector were applied. ... The azelaic acid concentration was not equal in the two solvents, due to the limited solubility in water. ...

Ildikó Száraz; Willis Forsling

2001-05-23T23:59:59.000Z

234

Gordon Research Conferences  

Science Journals Connector (OSTI)

...Robert Charles Allen, "Water in epoxy resins. Thermodynamics...Raman scat-tenng in gallium arsenide." Robert Silby, "Many...Princeton, NJ 08544. Water and Aqueous Solutions...structure and dynamics of water (A. H. Narten, discussion...

ALEXANDER M. CRUICKSHANK

1986-03-07T23:59:59.000Z

235

Hydrogen and minor element incorporation in synthetic rutile  

Science Journals Connector (OSTI)

...in a decrease in H solubility. Variation in the solubility of different oxides...substitution|solubility|spectroscopy...GPa, 1100C under water-saturated conditions...MnTiO3 (Ti), gallium arsenide (Ga), chromium...

G. D. Bromiley; N. Hilairet

236

Geochemical Evolution of a High Arsenic, Alkaline Pit-Lake in the Mother Lode Gold District, California  

Science Journals Connector (OSTI)

...cobalt metals, gallium arsenide, galena, wollastonite...ultrapure (MilleQ) water and analyzed as...account for its higher solubility in ground water relative to waters...reflect the lower solubility of CO2 in water with slightly higher...

Kaye S. Savage; Roger P. Ashley; Dennis K. Bird

237

Gordon Research Conferences: Program for 1967  

Science Journals Connector (OSTI)

...chromatography"; K. L. Hoy, "Uses of solubility parameter." 21 July. E. B...Davey, "Growth and properties of gallium arsenide films (C. Feldman, discussion...desert sand glass"; I. Burn, "Water in fused SiO2." 1 September...

W. George Parks

1967-03-10T23:59:59.000Z

238

Gordon Research Conferences  

Science Journals Connector (OSTI)

...developments in water-borne coatings...Hoy, "Separating solubility parameters of polymers...experiments." 18 July. Gallium arsenide (R. K. Wil-lardson...processes in surface waters"; T. Graedel...Thermodesorption of water from glass fiber...

Alexander M. Cruickshank

1985-03-01T23:59:59.000Z

239

Reference Data for the Density and Viscosity of Liquid Cadmium, Cobalt, Gallium, Indium, Mercury, Silicon, Thallium, and Zinc  

SciTech Connect (OSTI)

The available experimental data for the density and viscosity of liquid cadmium, cobalt, gallium, indium, mercury, silicon, thallium, and zinc have been critically examined with the intention of establishing both a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement, the technique employed and the presentation of the data, as specified by a series of criteria. The proposed standard reference correlations for the density of liquid cadmium, cobalt, gallium, indium, silicon, thallium, and zinc are characterized by percent deviations at the 95% confidence level of 0.6, 2.1, 0.4, 0.5, 2.2, 0.9, and 0.7, respectively. In the case of mercury, since density reference values already exist, no further work was carried out. The standard reference correlations for the viscosity of liquid cadmium, cobalt, gallium, indium, mercury, silicon, thallium, and zinc are characterized by percent deviations at the 95% confidence level of 9.4, 14.0, 13.5, 2.1, 7.3, 15.7, 5.1, and 9.3, respectively.

Assael, Marc J.; Armyra, Ivi J.; Brillo, Juergen; Stankus, Sergei V.; Wu Jiangtao; Wakeham, William A. [Chemical Engineering Department, Aristotle University, 54124 Thessaloniki (Greece); Institut fuer Materialphysik im Weltraum, Deutsches Zentrum fuer Luft- und Raumfahrt, 51170 Koeln (Germany); Kutateladze Institute of Thermophysics, Siberian Brunch of the Russian Academy of Sciences, Lavrentyev ave. 1, 630090 Novosibirsk (Russian Federation); Center of Thermal and Fluid Science, School of Energy and Power Engineering, Xi'an Jiaotong University, Shaanxi 710049 (China); Chemical Engineering Department, Imperial College, London SW7 2BY (United Kingdom)

2012-09-15T23:59:59.000Z

240

Bistability of self-modulation of the GaAs intrinsic stimulated picosecond radiation spectrum  

SciTech Connect (OSTI)

The bistability of self-modulation of the spectrum of the stimulated picosecond radiation that appears during picosecond optical pumping of GaAs is detected. The radiation is measured before it reaches the end faces of a sample. One set of equidistant modes occurs in the radiation spectrum at the radiation pulse front. A set of modes located at the center between the initial modes replaces the first set in the descending radiation branch. The intermode interval inside each set coincides with the calculated interval between the eigenmodes of the GaAs layer, which is an active cavity. The radiation rise time turns out to be an oscillating function of the photon energy. The spectrum evolution is self-consistent so that the time-integrated spectrum and the spectrum-integrated radiation pulse envelope have a smooth (without local singularities) shape. The revealed bistability explains the physical nature of the two radiation-induced states of population depletion between which subterahertz self-oscillations in the radiation field were detected earlier. The radiation spectrum self-modulation is assumed to be a variant of stimulated Raman scattering.

Ageeva, N. N.; Bronevoi, I. L., E-mail: bil@cplire.ru; Zabegaev, D. N.; Krivonosov, A. N. [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)] [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)

2013-08-15T23:59:59.000Z

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


241

Wet etching of GaAs using synchrotron radiation x rays  

Science Journals Connector (OSTI)

The results of room-temperature wet etching of GaAs using synchrotron-radiation x rays are described. Under x-rayillumination etching occurs on the n- GaAs surface in contact with an acid or base solution or even deionized water. The etching process is studied as functions of the electrolytes their concentration semiconductor doping level and x-ray intensity and energy. The etching mechanism is determined to be primarily electrochemical in nature but the x-ray radiation chemistry plays a role in the etching. Smoothly etchedsurfaces are achievable with a root-mean-square surface roughness of 0.7–2.0 nm. We also found that the etching rate increases substantially with the ratio of the sample size to the x-ray exposure size. This is accounted for by the rate-limiting effect on the charge transfer across the semiconductor-electrolyte junction. The chemistry of etchedsurfaces is studied using x-ray photoelectron spectroscopy and compared to that of as-received surfaces.

Qing Ma; Nicolaie Moldovan; Derrick C. Mancini; Richard A. Rosenberg

2001-01-01T23:59:59.000Z

242

Structural properties of Bi-terminated GaAs(0 0 1) surface  

Science Journals Connector (OSTI)

Electronic and structural properties of Bi-terminated reconstructions on GaAs(0 0 1) surface have been studied by scanning tunneling microscopy (STM) and synchrotron radiation core-level spectroscopy. A 2–3 monolayer thick Bi-layer was evaporated on a Ga-terminated GaAs(0 0 1) surface. By heating the surface, the reconstruction changed from (2 × 1) to (2 × 4). The ?2 phase with one top Bi dimer and one As or Bi dimer in the third atomic layer per surface unit cell is proposed to explain the STM images of the Bi/GaAs(0 0 1)(2 × 4) surface heated at 400 °C. Bi 5d photoemission from the Bi/GaAs(2 × 4) consisted of two components suggesting two different bonding sites for Bi atoms on the (2 × 4) surface. The variation of the surface sensitivity of the photoemission induced no changes in the intensities of the components indicating that the origins of both components lie in the first surface layer.

M. Ahola-Tuomi; P. Laukkanen; R.E. Perälä; M. Kuzmin; J. Pakarinen; I.J. Väyrynen; M. Adell

2006-01-01T23:59:59.000Z

243

Surface roughening during depth profiling by Secondary Ion Mass Spectrometry (SIMS) in GaAlAs and GaAs  

Science Journals Connector (OSTI)

During bombardment of Ga1?xAlxAs and GaAs with oxygen we found an abrupt transition to higher sputter rates, change of the useful yield and significant increase of surface roughness at a well defined depth, which...

M. Gericke; T. Lill; M. Trapp; C. -E. Richter…

244

IEEE ELECTRON DEVICE LETTERS, VOL. 30, NO. 6, JUNE 2009 593 GaAs MESFET With a High-Mobility  

E-Print Network [OSTI]

systems, including InGaAs [4], CdS [5], ZnO [6], and GaN [7]. To the best of our knowledge FET (MESFET) fabricated with an intentionally doped n-type planar GaAs NW channel grown on a semi

Li, Xiuling

245

Highly Ordered Ga Nanodroplets on a GaAs Surface Formed by a Focused Ion Beam Qiangmin Wei,1  

E-Print Network [OSTI]

Highly Ordered Ga Nanodroplets on a GaAs Surface Formed by a Focused Ion Beam Qiangmin Wei,1 Jie Lian,2,3 Wei Lu,4 and Lumin Wang1,5,* 1 Department of Materials Science and Engineering, University Arbor, Michigan 48109, USA 3 Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer

Lu, Wei

246

Precipitation in Fe-or Ni-implanted and annealed GaAs J. C. P. Changa)  

E-Print Network [OSTI]

of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 E. S. Harmon, M. R. Melloch, and J. M. Woodall School of Electrical Engineering, Purdue University, West Lafayette, Indiana 47907/semiconductor composites by ion implantation of Fe and Ni into GaAs and a subsequent anneal to nucleate clusters. Electron

Woodall, Jerry M.

247

Near-infrared sideband generation induced by intense far-infrared radiation in GaAs quantum wells  

E-Print Network [OSTI]

Near-infrared sideband generation induced by intense far-infrared radiation in GaAs quantum wells J illuminated with near-infrared NIR radiation at frequency nir and intense far-infrared FIR radiation from and quenching of photoluminescence PL .8,9 The nonlinear interaction of FIR and near-infrared NIR radiation

Kono, Junichiro

248

Development of Polarized Electron Source of GaAs-AlGaAs Superlattice and Strained GaAs  

Science Journals Connector (OSTI)

At Nagoya University, we have continued the development of GaAs polarized electron source (PES) for several years. Our test ... a gun producing (1–5) KeV polarized electrons and a standard 100 KeV Mott polarimete...

T. Nakanishi; S. Nakamura

1991-01-01T23:59:59.000Z

249

Photoluminescence from GaAs nanodisks fabricated by using combination of neutral beam etching and atomic hydrogen-assisted molecular beam epitaxy regrowth  

SciTech Connect (OSTI)

We have fabricated GaAs nanodisk (ND) structures by using a combination of neutral beam etching process and atomic hydrogen-assisted molecular beam epitaxy regrowth. We have observed clear photoluminescence (PL) emissions from GaAs NDs. The peak energy showed a blueshift due to the quantum confinement in three spatial dimensions, and it agreed with the theoretically estimated transition energy. The PL results also showed that the cap-layer disks act as radiative recombination centers. We have confirmed that the PL emission originates from the GaAs NDs, and our approach is effective for the fabrication of high quality ND structures.

Kaizu, Toshiyuki; Okada, Yoshitaka [Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Tamura, Yosuke; Igarashi, Makoto; Hu, Weiguo; Tsukamoto, Rikako [Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamashita, Ichiro [Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Samukawa, Seiji [Japan Science and Technology Agency, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan); Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2012-09-10T23:59:59.000Z

250

More Efficient Power Conversion for EVs: Gallium-Nitride Advanced Power Semiconductor and Packaging  

SciTech Connect (OSTI)

Broad Funding Opportunity Announcement Project: Delphi is developing power converters that are smaller and more energy efficient, reliable, and cost-effective than current power converters. Power converters rely on power transistors which act like a very precisely controlled on-off switch, controlling the electrical energy flowing through an electrical circuit. Most power transistors today use silicon (Si) semiconductors. However, Delphi is using semiconductors made with a thin layer of gallium-nitride (GaN) applied on top of the more conventional Si material. The GaN layer increases the energy efficiency of the power transistor and also enables the transistor to operate at much higher temperatures, voltages, and power-density levels compared to its Si counterpart. Delphi is packaging these high-performance GaN semiconductors with advanced electrical connections and a cooling system that extracts waste heat from both sides of the device to further increase the device’s efficiency and allow more electrical current to flow through it. When combined with other electronic components on a circuit board, Delphi’s GaN power transistor package will help improve the overall performance and cost-effectiveness of HEVs and EVs.

None

2010-02-01T23:59:59.000Z

251

E-Print Network 3.0 - antimony 133 Sample Search Results  

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

increases with the antimony molar fraction... boat with several compartments. The gallium solution contains GaAs for saturation and metallic antimony Source: Ecole...

252

Real-time reflectance-difference spectroscopy of GaAs molecular beam epitaxy homoepitaxial growth  

SciTech Connect (OSTI)

We report on real time-resolved Reflectance-difference (RD) spectroscopy of GaAs(001) grown by molecular beam epitaxy, with a time-resolution of 500 ms per spectrum within the 2.3–4.0 eV photon energy range. Through the analysis of transient RD spectra we demonstrated that RD line shapes are comprised of two components with different physical origins and determined their evolution during growth. Such components were ascribed to the subsurface strain induced by surface reconstruction and to surface stoichiometry. Results reported in this paper render RD spectroscopy as a powerful tool for the study of fundamental processes during the epitaxial growth of zincblende semiconductors.

Lastras-Martínez, A., E-mail: alm@cactus.iico.uaslp.mx, E-mail: alastras@gmail.com; Ortega-Gallegos, J.; Guevara-Macías, L. E.; Nuñez-Olvera, O.; Balderas-Navarro, R. E.; Lastras-Martínez, L. F. [Instituto de Investigación en Comunicación Optica, Universidad Autónoma de San Luis Potosí, Alvaro Obregón 64, San Luis Potosí, SLP 78000 (Mexico); Lastras-Montaño, L. A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Lastras-Montaño, M. A. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, California 93106 (United States)

2014-03-01T23:59:59.000Z

253

Energy levels of very short?period (GaAs) n ?(AlAs) n superlattices  

Science Journals Connector (OSTI)

The energy levels of very short?period (GaAs) n ?(AlAs) n superlattices (n?4) were investigated by photoluminescence(PL). The results show that these superlattices are type II but the lowest conduction bands are X x y for n?3 and X z for n=4 respectively. (Here X z is the valley with k parallel to the growth axis.) In both cases the X valleys are very close to each other. PL decay PL excitation and PL under uniaxial stress confirm this identification. Al0.5Ga0.5As shows very different behavior showing that even for n=1 our samples are true superlattices.

Weikun Ge; M. D. Sturge; W. D. Schmidt; L. N. Pfeiffer; K. W. West

1990-01-01T23:59:59.000Z

254

Large area, low capacitance, GaAs nanowire photodetector with a transparent Schottky collecting junction  

SciTech Connect (OSTI)

We present experimental results on a GaAs/Indium-Tin-Oxide Schottky-like heterojunction photodetector based on a nanowire device geometry. By distributing the active detecting area over an array of nanowires, it is possible to achieve large area detection with low capacitance. Devices with bare GaAs and passivated AlGaAs/GaAs nanowires are fabricated to compare the responsivity with and without surface passivation. We are able to achieve responsivity of >0.5A/W and Signal-Noise-Ratio in excess of 7?dB for 2?V applied reverse bias with passivated nanowire devices. Capacitance-voltage measurement yields <5?nF/cm{sup 2}, which shows a strong possibility for high-speed applications with a broad area device.

Seyedi, M. A., E-mail: seyedi@usc.edu; Yao, M.; O'Brien, J.; Dapkus, P. D. [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States)] [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States); Wang, S. Y. [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States) [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States); Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California, Santa Cruz, California 95064, USA and NASA Ames Research Center, Moffett Field, California 94035 (United States)

2013-12-16T23:59:59.000Z

255

Intermediate-band material based on GaAs quantum rings for solar cells  

SciTech Connect (OSTI)

The intermediate-band concept is invoked to explain the photoresponse spectra obtained for unbiased devices fabricated from GaAs quantum rings grown by a droplet epitaxy technique on lattice-matched Al{sub 0.3}Ga{sub 0.7}As barriers. The photoresponse spectra where measured at room temperature in the visible-near-infrared spectral range. The presence of the intermediate band in the device active region is confirmed by measuring the mid-infrared photoresponse, which is attributed to the intersubband transitions in the conduction band. The photocurrent was measured at room temperature and found to be about four orders of magnitude larger than the dark current in the voltage range of {+-} 4.0 V.

Wu Jiang; Shao Dali [Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Li Zhenhua; Kunets, Vasyl P.; Wang Zhiming; Salamo, G. J. [Institute of Nanoscale Materials Science and Engineering, Fayetteville, Arkansas 72701 (United States); Manasreh, M. O. [Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Institute of Nanoscale Materials Science and Engineering, Fayetteville, Arkansas 72701 (United States)

2009-08-17T23:59:59.000Z

256

Measurement of electron beam polarization from unstrained GaAs via two-photon photoemission  

SciTech Connect (OSTI)

Two-photon absorption of 1560 nm light was used to generate polarized electron beams from unstrained GaAs photocathodes of varying thickness: 625 {mu}m, 0.32 {mu}m, and 0.18 {mu}m. For each photocathode, the degree of spin polarization of the photoemitted beam was less than 50%, contradicting earlier predictions based on simple quantum mechanical selection rules for spherically-symmetric systems but consistent with the more sophisticated model of Bhat et al. (Phys. Rev. B 71 (2005) 035209). Polarization via two-photon absorption was the highest from the thinnest photocathode sample and comparable to that obtained via one-photon absorption (using 778 nm light), with values 40.3 +- 1.0% and 42.6 +- 1.0%, respectively.

McCarter, James L. [Univ. of Virginia, Charlottesville, VA (United States); Afanasev, A. [George Washington Univ., Washingon, DC (United States); Gay, T. J. [Univ. of Nebraska, Lincoln, NE (United States); Hansknecht, John C. [JLAB, Newport News, VA (United States); Kechiantz, A. [George Washington Univ., Washingon, DC (United States); Poelker, B. Matthew [JLAB, Newport News, VA (United States)

2014-02-01T23:59:59.000Z

257

Composite system based on CdSe/ZnS quantum dots and GaAs nanowires  

SciTech Connect (OSTI)

The possibility of fabricating a composite system based on colloidal CdSe/ZnS quantum dots and GaAs nanowires is demonstrated and the structural and emission properties of this system are investigated by electron microscopy and photoluminescence spectroscopy techniques. The good wettability and developed surface of the nanowire array lead to an increase in the surface density of quantum dots and, as a consequence, in the luminosity of the system in the 600-nm wavelength region. The photoluminescence spectrum of the quantum dots exhibits good temperature stability in the entire range 10-295 K. The impact of surface states on energy relaxation and the role of exciton states in radiative recombination in the quantum dots are discussed.

Khrebtov, A. I. [St. Petersburg Academic University-Nanotechnology Research and Education Center, Russian Academy of Sciences (Russian Federation)] [St. Petersburg Academic University-Nanotechnology Research and Education Center, Russian Academy of Sciences (Russian Federation); Talalaev, V. G. [St. Petersburg State University, Fock Institute of Physics (Russian Federation)] [St. Petersburg State University, Fock Institute of Physics (Russian Federation); Werner, P. [Max-Planck-Institut fuer Mikrostukturphysik (Germany)] [Max-Planck-Institut fuer Mikrostukturphysik (Germany); Danilov, V. V. [Vavilov State Optical Institute (Russian Federation)] [Vavilov State Optical Institute (Russian Federation); Artemyev, M. V. [Belarussian State University, Institute for Physicochemical Problems (Belarus)] [Belarussian State University, Institute for Physicochemical Problems (Belarus); Novikov, B. V. [St. Petersburg State University, Fock Institute of Physics (Russian Federation)] [St. Petersburg State University, Fock Institute of Physics (Russian Federation); Shtrom, I. V. [St. Petersburg Academic University-Nanotechnology Research and Education Center, Russian Academy of Sciences (Russian Federation)] [St. Petersburg Academic University-Nanotechnology Research and Education Center, Russian Academy of Sciences (Russian Federation); Panfutova, A. S. [Vavilov State Optical Institute (Russian Federation)] [Vavilov State Optical Institute (Russian Federation); Cirlin, G. E. [St. Petersburg Academic University-Nanotechnology Research and Education Center, Russian Academy of Sciences (Russian Federation)] [St. Petersburg Academic University-Nanotechnology Research and Education Center, Russian Academy of Sciences (Russian Federation)

2013-10-15T23:59:59.000Z

258

Fano Resonance in GaAs 2D Photonic Crystal Nanocavities  

SciTech Connect (OSTI)

We report the results of polarization resolved reflectivity experiments in GaAs air-bridge photonic crystals with L3 cavities. We show that the fundamental L3 cavity mode changes, in a controlled way, from a Lorentzian symmetrical lineshape to an asymmetrical form when the linear polarization of the incident light is rotated in the plane of the crystal. The different lineshapes are well fitted by the Fano asymmetric equation, implying that a Fano resonance is present in the reflectivity. We use the scattering matrix method to model the Fano interference between a localized discrete state (the cavity fundamental mode) and a background of continuum states (the light reflected from the crystal slab in the vicinity of the cavity) with very good agreement with the experimental data.

Valentim, P. T.; Guimaraes, P.S. S. [Departamento de Fisica, Universidade Federal de Minas Gerais, Belo Horizonte (Brazil); Instituto Nacional de Ciencia e Tecnologia de Nanodispositivos Semicondutores - INCT-DISSE (Brazil); Luxmoore, I. J.; Szymanski, D.; Whittaker, D. M.; Fox, A. M.; Skolnick, M. S. [Department of Physics and Astronomy, University of Sheffield, Sheffield (United Kingdom); Vasco, J. P. [Instituto de Fisica, Universidad de Antioquia, Medellin (Colombia); Vinck-Posada, H. [Departamento de Fisica, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota (Colombia)

2011-12-23T23:59:59.000Z

259

Infrared spectroscopy of amorphous hydrogenated GaAs: Evidence for H bridges  

Science Journals Connector (OSTI)

The infrared absorption spectra of hydrogenated amorphous GaAs show two prominent hydrogen-related bands at 530 and 1460 cm-1. These bands are very broad and they amount to most of the hydrogen-induced infrared absorption. The remaining structures are a number of comparatively sharp lines which we interpret as Ga-H and As-H modes in partial agreement with earlier investigations. We argue that the broad bands arise from near-stretching (1460 cm-1) and from wagging (530 cm-1) vibrations of H atoms situated in bridging positions between two Ga atoms. This assignment is supported by similar bands in Al-H polymers, a-GaP: H, and a-GaSb: H. A model calculation of the mode frequencies is also presented.

Z. P. Wang; L. Ley; M. Cardona

1982-09-15T23:59:59.000Z

260

Impact ionization in GaAs: A screened exchange density-functional approach  

SciTech Connect (OSTI)

Results are presented of a fully ab initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave method. The calculated impact ionization rates show a marked orientation dependence in k space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab initio calculations of pair production rates in new and more complex materials.

Picozzi, S., Asahi, R., Geller, C.B., Continenza, A., and Freeman, A.J.

2001-08-13T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Open-tube method for diffusion of zinc into GaAs  

SciTech Connect (OSTI)

Highly reproducible zinc diffusions from 0.03 to 1.5 /mu/m have been made into GaAs using a CVD zinc-doped silica source capped with phosphosilicate glass. This structure permitted the use of an open-tube, flowing inert gas diffusion system. Diffusions were made from 400/degree/ to 700/degree/C, with surface hole concentrations from 0.1 to 1.0*10/sup 20/ cm/sup -3/, and junction depths from 300A to 1.5 /mu/m. The diffusion coefficient and the hole concentration obtained by this technique are very close to those obtained by sealed ampul techniques using a Zn/sub 3/A/sub 2/ source. However, this open-tube system is more convenient to use, and gives highly reproducible results. 13 refs.

Field, R.J.; Ghandhi, S.K.

1982-07-01T23:59:59.000Z

262

Excitonic and free-carrier polarizations of bulk GaAs studied by femtosecond coherent spectroscopy  

Science Journals Connector (OSTI)

The transient third-order polarization at the band gap of undoped and p-doped GaAs is investigated by spectrally and temporally resolved four-wave mixing. Excitonic and free-carrier contributions simultaneously excited within the bandwidth of the 100-fs pulses are clearly distinguished by their different spectral envelopes. The excitonic part dominates at carrier densities below 1016 cm-3 and shows a time evolution governed by exciton–free-carrier scattering and by many-body effects. At higher density, the free-carrier polarization has a strength similar to the exciton contribution and exhibits a spectrum resonant to the femtosecond pulses with a photon-echo-like temporal behavior. The data are analyzed by a numerical solution of the semiconductor Bloch equations including an ensemble Monte Carlo simulation of the scattering dynamics of the carriers. The theoretical model is in good agreement with the experimental results.

A. Leitenstorfer; A. Lohner; K. Rick; P. Leisching; T. Elsaesser; T. Kuhn; F. Rossi; W. Stolz; K. Ploog

1994-06-15T23:59:59.000Z

263

Photoresponse of the FR3 electron-spin-resonance signal in GaAs  

Science Journals Connector (OSTI)

The photoresponse of the FR3 electron-spin-resonance (ESR) signal in GaAs has been studied. Excitation and quenching of the FR3 ESR is shown to result from the optically induced charge exchange between the FR3 center and the AsGa antisite. The FR3 ESR can be persistently excited with photons in the range 1.0 eV

U. Kaufmann; W. Wilkening; M. Baeumler

1987-11-15T23:59:59.000Z

264

Tailoring broadband light trapping of GaAs and Si substrates by self-organised nanopatterning  

SciTech Connect (OSTI)

We report on the formation of high aspect ratio anisotropic nanopatterns on crystalline GaAs (100) and Si (100) substrates exploiting defocused Ion Beam Sputtering assisted by a sacrificial self-organised Au stencil mask. The tailored optical properties of the substrates are characterised in terms of total reflectivity and haze by means of integrating sphere measurements as a function of the morphological modification at increasing ion fluence. Refractive index grading from sub-wavelength surface features induces polarisation dependent anti-reflection behaviour in the visible-near infrared (VIS-NIR) range, while light scattering at off-specular angles from larger structures leads to very high values of the haze functions in reflection. The results, obtained for an important class of technologically relevant materials, are appealing in view of photovoltaic and photonic applications aiming at photon harvesting in ultrathin crystalline solar cells.

Martella, C.; Chiappe, D.; Mennucci, C.; Buatier de Mongeot, F. [Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova (Italy)

2014-05-21T23:59:59.000Z

265

Boron-Silicon complex defects in GaAs: An ab initio study  

Science Journals Connector (OSTI)

First principles calculations have been performed to investigate defect equilibria of the silicon–boron pair complex (Si–B) in a GaAs matrix. For several charge states the formation energies were evaluated within the Car–Parrinello scheme considering cation and anion substitutional site defects. The calculations including the full relaxation of all ionic coordinates investigate native defects and isolated substitutional silicon (Si) and boron (B) impurities. The obtained formation energies are used to calculate the impurity concentration for different growth conditions. These results can be used to estimate the effect of different thermal profiles on the distribution and electrical state of Si and B defects which is interesting for classical process simulations.

R. Leitsmann; F. Chicker; Ph. Plänitz; C. Radehaus; U. Kretzer; M. Scheffer-Czygan; S. Eichler

2011-01-01T23:59:59.000Z

266

Self-cleaning and surface recovery with arsine pretreatment in ex situ atomic-layer-deposition of Al2O3 on GaAs  

E-Print Network [OSTI]

. heavily doped GaAs 001 substrates at 650 °C with TMG Ga CH3 3 and arsine AsH3 V/III=23 with disilane Si2H6

267

Simulation of quantum dots size and spacing effect for intermediate band solar cell application based on InAs quantum dots arrangement in GaAs  

SciTech Connect (OSTI)

Intermediate band solar cell (IBSC) has become a promising technology in increasing solar cell efficiency. In this work we compare absorption coefficient profile between InAs quantum dots with GaAs bulk. We calculate the efficiency of GaAs bulk and GaAs doped with 2, 5, and 10 nm InAs quantum dot. Effective distances in quantum dot arrangement based on electron tunneling consideration were also calculated. We presented a simple calculation method with low computing power demand. Results showed that arrangement of quantum dot InAs in GaAs can increase solar cell efficiency from 23.9 % initially up to 60.4%. The effective distance between two quantum dots was found 2 nm in order to give adequate distance to prevent electron tunneling and wave functions overlap.

Hendra, P. I. B., E-mail: ib.hendra@gmail.com; Rahayu, F., E-mail: ib.hendra@gmail.com; Darma, Y., E-mail: ib.hendra@gmail.com [Physical Vapor Deposition Laboratory, Physics of Material Electronics Research, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

2014-03-24T23:59:59.000Z

268

High quality metamorphic graded buffers with lattice-constants intermediate to GaAs an InP for device applications  

E-Print Network [OSTI]

We have investigated the use of a continuous, linear grading scheme for compositionally-graded metamorphic InxGal-As buffers on GaAs, which can be used as virtual substrates for optical emitters operating at wavelengths > ...

Lee, Kenneth Eng Kian

2009-01-01T23:59:59.000Z

269

Piezoelectric surface acoustical phonon amplification in graphene on a GaAs substrate  

SciTech Connect (OSTI)

We study the interaction of Dirac Fermions in monolayer graphene on a GaAs substrate in an applied electric field by the combined action of the extrinsic potential of piezoelectric surface acoustical phonons of GaAs (piezoelectric acoustical (PA)) and of the intrinsic deformation potential of acoustical phonons in graphene (deformation acoustical (DA)). We find that provided the dc field exceeds a threshold value, emission of piezoelectric (PA) and deformation (DA) acoustical phonons can be obtained in a wide frequency range up to terahertz at low and high temperatures. We found that the phonon amplification rate R{sup PA,DA} scales with T{sub BG}{sup S?1} (S=PA,DA), T{sub BG}{sup S} being the Block?Gru{sup ¨}neisen temperature. In the high-T Block?Gru{sup ¨}neisen regime, extrinsic PA phonon scattering is suppressed by intrinsic DA phonon scattering, where the ratio R{sup PA}/R{sup DA} scales with ?1/?(n), n being the carrier concentration. We found that only for carrier concentration n?10{sup 10}cm{sup ?2}, R{sup PA}/R{sup DA}>1. In the low-T Block?Gru{sup ¨}neisen regime, and for n=10{sup 10}cm{sup ?2}, the ratio R{sup PA}/R{sup DA} scales with T{sub BG}{sup DA}/T{sub BG}{sup PA}?7.5 and R{sup PA}/R{sup DA}>1. In this regime, PA phonon dominates the electron scattering and R{sup PA}/R{sup DA}<1 otherwise. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as an acoustical phonon amplifier and a frequency-tunable acoustical phonon device.

Nunes, O. A. C., E-mail: oacn@unb.br [Institute of Physics, University of Brasilia, Brasilia, 70910-900 DF (Brazil)

2014-06-21T23:59:59.000Z

270

Microstructure characterization of Cu,Ge/n-type GaAs ohmic contacts M. 0. Aboelfotoh, S. Oktyabrsky, and J. Narayan  

E-Print Network [OSTI]

contacts of Ge/Pd/n-type GaAs have been proposed.4 This contact scheme involves the deposition of a metal at 325 "C for 30 min, the entire layer of Pd is consumed in the formation of a palladium germanide layer to the Ge/Pd contacts,' and that n-channel GaAs metal- semiconductor field-effect transistors using the q

Woodall, Jerry M.

271

EL2-related studies in irradiated and implanted GaAs Laboratoire de Physique de la Matire (associ au CNRS), Institut National des Sciences Appliques de Lyon,  

E-Print Network [OSTI]

donneur profond EL2 est un défaut très important par le rôle qu'il joue dans la compensation du matériau in the compensation of undoped semi-insulating GaAs. The knowledge of the exact EL2 structure becomes of even greater semi-insulating (SI) GaAs uses the liquid- encapsulated Czochralski process with the As vapor pressure

Boyer, Edmond

272

Formation of anion vacancies by Langmuir evaporation from InP and GaAs (110) surfaces at low temperatures  

Science Journals Connector (OSTI)

A low-temperature Langmuir-evaporation regime is observed by scanning tunneling microscopy on InP and GaAs (110) surfaces. It is characterized by the formation of positively charged anion monovacancies even at room temperature. This vacancy formation has been studied as a function of time on InP between 293 and 480 K and on GaAs at room temperature. On InP the maximum vacancy concentration is obtained at 435 K. At this temperature 1.2% of the P surface sites are vacant. At higher temperatures the concentration decreases. The observations are explained by a competition between, on the one hand, P-vacancy–adatom pair production followed by P2 molecule formation and desorption and, on the other hand, phosphorus outdiffusion from the bulk.

Ph. Ebert, M. Heinrich, M. Simon, K. Urban, and M. G. Lagally

1995-04-15T23:59:59.000Z

273

COMPARATIVE STUDY OF CdTe AND GaAs PHOTOREFRACTIVE PERFORMANCES FROM 1m TO 1.55m  

E-Print Network [OSTI]

1 COMPARATIVE STUDY OF CdTe AND GaAs PHOTOREFRACTIVE PERFORMANCES FROM 1µm TO 1.55µm L.A. de CdTe at different wavelengths from 1.06µm to 1.55µm. The sensitivity and performances of different for the extension of the photorefractive effect towards the wavelength region of 1.3-1.5µm. CdTe appears

Paris-Sud XI, Université de

274

Role of GaAs surface clearing in plasma deposition of silicon nitride films for encapsulated annealing  

SciTech Connect (OSTI)

The role of GaAs surface cleaning and plasma reactor cleaning prior to deposition of silicon nitride films for encapsulated annealing has been investigated. X-ray photoelectron spectroscopy was employed to determine the surface characteristics of GaAs treated with HCl, HF, and NH4OH solutions preceded by a degreasing procedure. The HCl clean left the least amount of oxygen on the surface. Fluorine contamination resulting from the CF4 plasma used to clean the reactor was found to be located at the film-substrate interface by Auger electron spectroscopy with argon-ion sputtering. A modified deposition procedure was developed to eliminate the fluorine contamination. Plasma deposition of silicon nitride encapsulating films was found to modify the I-V characteristics of Schottky diodes subsequently formed on GaAs surface. The reverse current of the diodes was slightly reduced. Substrates implanted with Si at 100 keV and a dose of 5 x 10 to the 12th/sq cm showed a peak electron concentration of 1.7 x 10 to the 17th/cu cm at a depth of 0.1-micron with 60 percent activation after encapsulation and annealing at 800 C for 7 min. 9 references.

Valco, G.J.; Kapoor, V.J.

1985-06-01T23:59:59.000Z

275

Dual passivation of GaAs (110) surfaces using O{sub 2}/H{sub 2}O and trimethylaluminum  

SciTech Connect (OSTI)

The nucleation and passivation of oxide deposition was studied on defect-free GaAs (110) surfaces to understand passivation of surfaces containing only III-V heterobonds. The passivation process on GaAs (110) was studied at the atomic level using scanning tunneling microscopy while the electronic structure was determined by scanning tunneling spectroscopy (STS). The bonding of the oxidant and reductant were modeled with density functional theory. To avoid Fermi level pinning during gate oxide atomic layer deposition, a dual passivation procedure was required using both a reductant, trimethylaluminum (TMA), and an oxidant, O{sub 2} or H{sub 2}O. Dosing GaAs (110) with TMA resulted in the formation of an ordered complete monolayer of dimethylaluminum which passivates the group V dangling bonds but also forms metal-metal bonds with conduction band edge states. These edge states were suppressed by dosing the surface with oxidants O{sub 2} or H{sub 2}O which selectively react with group III-aluminum bonds. The presence of an ordered Al monolayer with a high nucleation density was indirectly confirmed by XPS and STS.

Kent, Tyler J.; Edmonds, Mary [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States)] [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States); Chagarov, Evgueni [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States); Droopad, Ravi [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)] [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States); Kummel, Andrew C. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States) [Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093 (United States); Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States)

2013-12-28T23:59:59.000Z

276

Lewis Base Adduct Stabilized Organogallium Azides:? Synthesis and Dynamic NMR Spectroscopic Studies of Novel Precursors to Gallium Nitride and Role of Ammonia as Reactive Carrier Gas  

Science Journals Connector (OSTI)

Lewis Base Adduct Stabilized Organogallium Azides:? Synthesis and Dynamic NMR Spectroscopic Studies of Novel Precursors to Gallium Nitride and Role of Ammonia as Reactive Carrier Gas ... Solvents were dried under argon according to standard methods; n-pentane and toluene were stored over Na/K alloy, and diethyl ether and thf over potassium benzophenoate (residual water solubility in other solvents than thf. ...

Alexander Miehr; Mike R. Mattner; Roland A. Fischer

1996-04-16T23:59:59.000Z

277

Quantum efficiency temporal response and lifetime of a GaAs cathode in SRF electron gun  

SciTech Connect (OSTI)

RF electron guns with a strained super lattice GaAs cathode can generate polarized electron beam of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface. In a normal conducting RF gun, the extremely high vaccum required by these cathodes can not be met. We report on an experiment with a superconducting SRF gun, which can maintain a vacuum of nearly 10-12 torr because of cryo-pumping at the temperature of 4.2K. With conventional activation, we obtained a QE of 3% at 532 nm, with lifetime of nearly 3 days in the preparation chamber. We plan to use this cathode in a 1.3 GHz 1/2 cell SRF gun to study its performance. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper. Future particle accelerators such as eRHIC and ILC require high brightness, high current polarized electrons Recently, using a superlattice crystal, the maximum polarization of 95% was reached. Activation with Cs,O lowers the electron affinity and makes it energetically possible for all the electrons excited in to the conduction band and reach the surface to escape into the vacuum. Presently the polarized electron sources are based on DC gun, such as that at the CEBAF at Jlab. In these devices, the life time of the cathode is extended due to the reduced back bombardment in their UHV conditions. However, the low accelerating gradient of the DC guns lead to poor longitudinal emittance. The higher accelerating gradient of the RF gun generates low emittance beams. Superconducting RF guns combine the excellent vacuum conditions of the DC guns with the higher accelerating gradients of the RF guns and provide potentially a long lived cathode with very low transverse and longitudinal emittance. In our work at BNL, we successfully activated the GaAs. The quantum efficient is 3% at 532 nm and is expected to improve further. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper.

Wang, E.; Ben-Zvi, I.; Kewisch, J.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

2010-05-23T23:59:59.000Z

278

Zone Melting  

Science Journals Connector (OSTI)

...four-turn induction coils of water-cooled copper tubing...by introducing a bit of water vapor into the hydrogen...apparatus (6). The water vapor combines with the...indium antimo-nide, gallium arsenide, gallium phos-phide...

W. G. Pfann

1962-03-30T23:59:59.000Z

279

Characterization of the CEBAF 100 kV DC GaAs Photoelectron Gun Vacuum System  

SciTech Connect (OSTI)

A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower part of the UHV range. Measured NEG pump speed is high at pressures above 5×10^?11 Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers.

M.L. Stutzman; P. Adderley; J. Brittian; J. Clark; J. Grames; J. Hansknecht; G.R. Myneni; M. Poelker

2007-05-01T23:59:59.000Z

280

Diffusion-limited kinetics of terrace growth on GaAs(110)  

SciTech Connect (OSTI)

The kinetics of thermal annealing of surface roughness created by low-energy ion bombardment of GaAs(110) is characterized in situ by a low-energy electron diffraction (LEED) spot profile analysis to investigate the underlying diffusion mechanisms involved. The coarsening of the step-and-terrace structure on the partially annealed surface is observed, showing power-law growth of the average terrace width l{approx}t{sup {beta}} with an exponent {beta}=0.23-0.26 over two orders of magnitude in annealing time t in the temperature range 660-740 K. However, the terrace height distribution is shown to vary little with annealing, providing evidence for an Ehrlich-Schwoebel barrier at step edges. The LEED analysis also detects an additional, low amplitude height distribution contributing an interface width of less than 0.03 nm, which is interpreted as elastic deformation around subsurface defects and exhibits much slower relaxation kinetics during annealing than the terrace growth.

Piercy, P.; Castonguay, A.M.-J. [Department of Physics, University of Ottawa, Ottawa, Ontario, K1N 6N5 (Canada)

2005-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Barium iron arsenide, barium cobalt arsenide, barium nickel arsenide single crystals and superconductivity upon cobalt doping  

SciTech Connect (OSTI)

The crystal structure and physical properties of BaFe{sub 2}As{sub 2}, BaCo{sub 2}As{sub 2}, and BaNi{sub 2}As{sub 2} single crystals are surveyed. BaFe{sub 2}As{sub 2} gives a magnetic and structural transition at T{sub N} = 132(1) K, BaCo{sub 2}As{sub 2} is a paramagnetic metal, while BaNi{sub 2}As{sub 2} has a structural phase transition at T{sub 0} = 131 K, followed by superconductivity below {Tc} = 0.69 K. The bulk superconductivity in Co-doped BaFe{sub 2}As{sub 2} below {Tc} = 22 K is demonstrated by resistivity, magnetic susceptibility, and specific heat data. In contrast to the cuprates, the Fe-based system appears to tolerate considerable disorder in the transition metal layers. First principles calculations for BaFe{sub 1.84}Co{sub 0.16}As{sub 2} inter-band scattering due to Co is weak.

Ronning, Filip [Los Alamos National Laboratory; Sefat, A S [ORNL; Mcguire, M M [ORNL; Sales, B [ORNL; Jin, R [ORNL; Mandrus, D [ORNL

2009-01-01T23:59:59.000Z

282

The influence of prestrained metalorganic vapor phase epitaxial gallium-nitride templates on hydride vapor phase epitaxial growth  

Science Journals Connector (OSTI)

We have varied the strain situation in metalorganic vapor phase epitaxial (MOVPE) grown gallium-nitride (GaN) by exchanging the nucleation layer and by inserting a submono-Si x N y -interlayer in the first few hundred nanometers of growth on sapphire substrates. The influence on the MOVPE template and subsequent hydride vapor phase epitaxial (HVPE) growth could be shown by in-situ measurements of the sample curvature. Using the results of these investigations we have established a procedure to confine the curvature development in MOVPE and HVPE growth to a minimum. By increasing the layer thickness in HVPE we could create self-separated freestanding GaN layers with small remaining curvature.

2014-01-01T23:59:59.000Z

283

Surface reactivity and oxygen migration in amorphous indium-gallium-zinc oxide films annealed in humid atmosphere  

SciTech Connect (OSTI)

An isotope tracer study, i.e., {sup 18}O/{sup 16}O exchange using {sup 18}O{sub 2} and H{sub 2}{sup 18}O, was performed to determine how post-deposition annealing (PDA) affected surface reactivity and oxygen diffusivity of amorphous indium–gallium–zinc oxide (a-IGZO) films. The oxygen tracer diffusivity was very high in the bulk even at low temperatures, e.g., 200?°C, regardless of PDA and exchange conditions. In contrast, the isotope exchange rate, dominated by surface reactivity, was much lower for {sup 18}O{sub 2} than for H{sub 2}{sup 18}O. PDA in a humid atmosphere at 400?°C further suppressed the reactivity of O{sub 2} at the a-IGZO film surface, which is attributable to –OH-terminated surface formation.

Watanabe, Ken, E-mail: Watanabe.Ken@nims.go.jp [International Center for Young Scientists (ICYS-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan)] [International Center for Young Scientists (ICYS-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan); Lee, Dong-Hee [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba 305-0044 (Japan) [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba 305-0044 (Japan); Materials and Structures Laboratory (MSL), Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Sakaguchi, Isao; Haneda, Hajime [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba 305-0044 (Japan)] [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba 305-0044 (Japan); Nomura, Kenji [Frontier Research Center, Tokyo Institute of Technology, Mailbox S2-13, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan)] [Frontier Research Center, Tokyo Institute of Technology, Mailbox S2-13, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Kamiya, Toshio [Materials and Structures Laboratory (MSL), Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan) [Materials and Structures Laboratory (MSL), Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Materials Research Center for Element Strategy (MCES), Mailbox S2-13, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Hosono, Hideo [Materials and Structures Laboratory (MSL), Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan) [Materials and Structures Laboratory (MSL), Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Frontier Research Center, Tokyo Institute of Technology, Mailbox S2-13, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Materials Research Center for Element Strategy (MCES), Mailbox S2-13, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan); Ohashi, Naoki, E-mail: Ohashi.Naoki@nims.go.jp [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba 305-0044 (Japan) [Optical and Electronic Materials Unit, NIMS, 1-1 Namiki, Tsukuba 305-0044 (Japan); Materials Research Center for Element Strategy (MCES), Mailbox S2-13, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-0026 (Japan)

2013-11-11T23:59:59.000Z

284

Chirped-pulse manipulated carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs  

SciTech Connect (OSTI)

Chirped pulse controlled carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs are investigated by degenerate pump-probe technique. Varying the chirped condition of excited pulse from negative to positive increases the carrier relaxation time so as to modify the dispersion and reshape current pulse in time domain. The spectral dependence of carrier dynamics is analytically derived and explained by Shockley-Read Hall model. This observation enables the new feasibility of controlling carrier dynamics in ultrafast optical devices via the chirped pulse excitations.

Lee, Chao-Kuei, E-mail: chuckcklee@yahoo.com [Department of Photonics, National Sun-Yat-Sen University, Kaohsiung 80400, Taiwan (China); Lin, Yuan-Yao [Department of Electrical Engineering, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30010, Taiwan (China); Lin, Sung-Hui [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lin, Gong-Ru [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan (China); Pan, Ci-Ling [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Physics, National Tsing Hwa University, Hsinchu 30010, Taiwan (China)

2014-04-28T23:59:59.000Z

285

Dopant atom clustering and charge screening induced roughness of electronic interfaces in GaAs p-n multilayers  

Science Journals Connector (OSTI)

The roughness of the electronic interfaces of p-n GaAs multilayers is investigated by cross-sectional scanning tunneling microscopy. Two physically different contributions to the roughness are found, both much larger than the underlying atomically sharp “metallurgical” interface. The roughness arises from the individual electrostatic screening fields around each dopant atom near the interface and from a clustering of dopant atoms. The latter leads to charge-carrier-depleted zones extending locally through the entire nominally homogeneously doped layer for layer thicknesses close to the cluster dimension, hence limiting the precision of the spatial and energetic positioning of the Fermi energy in nanoscale semiconductor structures.

N. D. Jäger, K. Urban, E. R. Weber, and Ph. Ebert

2002-05-24T23:59:59.000Z

286

Changes of defect and active-dopant concentrations induced by annealing of highly Si-doped GaAs  

Science Journals Connector (OSTI)

We identified point defects and dopant atoms and measured their concentrations in as-grown and post-growth annealed highly Si-doped GaAs by scanning tunneling microscopy. The annealing under As atmosphere reduces the concentration of Si atoms incorporated into Si pairs and clusters by cluster dissolution, while the concentrations of Si donors, Si donor–Ga vacancy complexes, and Si donor–As vacancy complexes increase. For the dissolution of the Si clusters during heat treatment, a Ga-vacancy-mediated mechanism is suggested.

C. Domke, Ph. Ebert, and K. Urban

1998-02-15T23:59:59.000Z

287

Electronic properties of adsorbates on GaAs,,001...-c,,28.../,,24... Darby L. Winn, Michael J. Hale, Tyler J. Grassman, Jonathan Z. Sexton, and  

E-Print Network [OSTI]

Electronic properties of adsorbates on GaAs,,001...-c,,2Ã?8.../,,2Ã?4... Darby L. Winn, Michael J tunneling spectroscopy STS and density functional theory DFT were used to study four different adsorbates' O that out of the four adsorbates studied, only one left the Fermi level unpinned, Ga2O. DFT calculations

Kummel, Andrew C.

288

Spin-Cast Deposition of CdSe-CdS Core-Shell Colloidal Quantum Dots on Doped GaAs Substrates: Structural and Optical Characterization  

Science Journals Connector (OSTI)

The detailed study of the effects of spin recipe and GaAs substrate doping (i.e., semi-insulating, n-type, or p-type) on the structural and optical properties of spin-cast CdSe-CdS core-shell CQDs provides insight into the surface adsorption and charge ... Keywords: Charge transfer, colloidal quantum dots, hybrid junctions, photoluminescence

A. D. Stiff-Roberts; Wanming Zhang; Jian Xu; Hongying Peng; H. O. Everitt

2007-07-01T23:59:59.000Z

289

Metal-insulator-semiconductor structure on low-temperature grown GaAs M. Young, W. Li, and T. P. Ma  

E-Print Network [OSTI]

Metal-insulator-semiconductor structure on low-temperature grown GaAs A. Chen,a M. Young, W. Li Received 28 July 2006; accepted 30 October 2006; published online 7 December 2006 The metal-insulator dielectrics and metal-insulator-semiconductor MIS structures; for ex- ample, in situ deposited Ga2O3 Gd2O3

Woodall, Jerry M.

290

ELSEWER Journal of Magnetism and Magnetic Materials 169 (1997) 261-270 Superparamagnetic behavior of Fe,GaAs precipitates in GaAs  

E-Print Network [OSTI]

ELSEWER Journal of Magnetism and Magnetic Materials 169 (1997) 261-270 Superparamagnetic behavior; revised 6 December 1996 Abstract We present magnetization measurements on Fe3GaAs clusters distributed-dependent magnetization well above the blocking temperature indicate a particle size distribution in agreement

Woodall, Jerry M.

291

Vacancy migration, adatom motion, a.nd atomic bistability on the GaAs(110) surface studied by scanning tunneling microscopy  

E-Print Network [OSTI]

Vacancy migration, adatom motion, a.nd atomic bistability on the GaAs(110) surface studied temperature are reported. The slow dynamic behavior of vacancies and As adatoms can be resolved within a time scale of about one minute, The vacancies and As adatoms are observed to move preferably along the [110

292

Electrical Bias as an Alternate Method for Reproducible Measurement of Copper Indium Gallium Diselenide (CIGS) Photovoltaic Modules: Preprint  

SciTech Connect (OSTI)

Light-to-dark metastable changes in thin-film photovoltaic (PV) modules can introduce uncertainty when measuring module performance on indoor flash testing equipment. This study describes a method to stabilize module performance through forward-bias current injection rather than light exposure. Measurements of five pairs of thin-film copper indium gallium diselenide (CIGS) PV modules indicate that forward-bias exposure maintained the PV modules at a stable condition (within 1%) while the unbiased modules degraded in performance by up to 12%. It was additionally found that modules exposed to forward bias exhibited stable performance within about 3% of their long-term outdoor exposed performance. This carrier-injection method provides a way to reduce uncertainty arising from fast transients in thin-film module performance between the time a module is removed from light exposure and when it is measured indoors, effectively simulating continuous light exposure by injecting minority carriers that behave much as photocarriers do. This investigation also provides insight into the initial light-induced transients of thin-film modules upon outdoor deployment.

Deline, C.; Stokes, A.; Silverman, T. J.; Rummel, S.; Jordan, D.; Kurtz, S.

2012-08-01T23:59:59.000Z

293

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

294

Magnetic anisotropies in epitaxial Fe{sub 3}O{sub 4}/GaAs(100) patterned structures  

SciTech Connect (OSTI)

Previous studies on epitaxial Fe{sub 3}O{sub 4} rings in the context of spin-transfer torque effect have revealed complicated and undesirable domain structures, attributed to the intrinsic fourfold magnetocrystalline anisotropy in the ferrite. In this Letter, we report a viable solution to this problem, utilizing a 6-nm-thick epitaxial Fe{sub 3}O{sub 4} thin film on GaAs(100), where the fourfold magnetocrystalline anisotropy is negligible. We demonstrate that in the Fe{sub 3}O{sub 4} planar wires patterned from our thin film, such a unique magnetic anisotropy system has been preserved, and relatively simple magnetic domain configurations compared to those previous reports can be obtained.

Zhang, W., E-mail: xiaotur@gmail.com; Zhang, D.; Yuan, S. J.; Huang, Z. C.; Zhai, Y. [Department of Physics, Southeast University, Nanjing 211189 (China); Wong, P. K. J. [NanoElectronics Group, MESA Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede (Netherlands); Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Wu, J. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Xu, Y. B. [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York, YO10 5DD (United Kingdom)

2014-10-15T23:59:59.000Z

295

k?p results for the absolute absorption coefficients of GaAs and biaxially strained ZnTe  

Science Journals Connector (OSTI)

Our calculations of the absolute absorption coefficients of GaAs and biaxially strained ZnTe single crystal layers is based on a 14×14 k?p model description of the band structure close to the Brillouin-zone center of the direct-gap zinc-blende semiconductors. The parameters of this model (momentum matrix elements, band separations at the ? point, effective masses) are known from fitting to independent experiments. The interband absorption continuum near the fundamental gap is calculated by multiplying the single-particle absorption coefficients from heavy- and light-hole valence bands with separate Sommerfeld corrections in order to account for the electron-hole interaction. Our theoretical results, which are obtained without any fitting parameters, are in good quantitative agreement with experimental data.

H. Mayer; U. Rössler; M. Ruff

1993-05-15T23:59:59.000Z

296

Capture of hot holes by shallow acceptors in p-type GaAs studied by picosecond infrared spectroscopy  

Science Journals Connector (OSTI)

Picosecond recombination of free holes with shallow acceptors in p-doped GaAs is directly monitored via spectrally and temporally resolved infrared studies. Neutral Zn impurities are photoionized by picosecond excitation in the wavelength range around 5 ?m. The recombination dynamics of the free carriers with ionized acceptors is measured via transient changes of the acceptor deionization band at photon energies close to the band gap. Hole capture is observed on a time scale of up to 100 ps following nonexponential kinetics. The data are analyzed with the help of model calculations considering single-step as well as multiple-step trapping mechanisms. Emission of single longitudinal-optical phonons is found to be the main mechanism of picosecond recombination.

M. Woerner; A. Lohner; T. Elsaesser; W. Kaiser

1993-05-15T23:59:59.000Z

297

Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures  

SciTech Connect (OSTI)

We report on the intense terahertz emission from InAs/GaAs quantum dot (QD) structures grown by molecular beam epitaxy. Results reveal that the QD sample emission was as high as 70% of that of a p-type InAs wafer, the most intense semiconductor emitter to date. Excitation wavelength studies showed that the emission was due to absorption in strained undoped GaAs, and corresponds to a two order-of-magnitude enhancement. Moreover, it was found that multilayer QDs emit more strongly compared with a single layer QD sample. At present, we ascribe the intense radiation to huge strain fields at the InAs/GaAs interface.

Estacio, Elmer; Pham, Minh Hong; Takatori, Satoru; Cadatal-Raduban, Marilou; Nakazato, Tomoharu; Shimizu, Toshihiko; Sarukura, Nobuhiko [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Somintac, Armando; Defensor, Michael; Awitan, Fritz Christian B.; Jaculbia, Rafael B.; Salvador, Arnel [National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines); Garcia, Alipio [Department of Physical Sciences, University of the Philippines, Baguio City 2600 (Philippines)

2009-06-08T23:59:59.000Z

298

Perpendicular-to-Parallel Spin Reorientation in a Mn-Doped GaAs Quantum Canting or Phase Separation  

SciTech Connect (OSTI)

It is well known that the magnetic anisotropy in a compressively-strained Mn-doped GaAs film changes from perpendicular to parallel with increasing hole concentration p. We study this reorientation transition at T = 0 for a quantum well with Mn impurities confined to the z = 0 plane. With increasing p, the angle 0 that minimizes the energy E increases continuously from 0 (perpendicular anisotropy) to /2 (parallel anisotropy) within some range of p. The shape of Emin(p) suggests that the quantum well becomes phase separated with regions containing low hole concentrations and perpendicular moments interspersed with other regions containing high hole concentrations and parallel moments. However, consideration of the Coulomb energy costs associated with phase separation suggests that the true magnetic state in the transition region is canted with 0 < < /2.

Fishman, Randy Scott [ORNL; Reboredo, Fernando A [ORNL; Brandt, Alex B [ORNL; Moreno, Juana [University of North Dakota, Grand Forks

2007-01-01T23:59:59.000Z

299

Kinetics of band bending and electron affinity at GaAs(001) surface with nonequilibrium cesium overlayers  

SciTech Connect (OSTI)

The dosage dependences of surface band bending and effective electron affinity under cesium deposition on the Ga-rich GaAs(001) surface, along with the relaxation of these electronic properties after switching off the Cs source are experimentally studied by means of modified photoreflectance spectroscopy and photoemission quantum yield spectroscopy. At small Cs coverages, below half of a monolayer, additional features in the dosage dependence and subsequent downward relaxation of the photoemission current are determined by the variations of band bending. At coverages above half of a monolayer the upward relaxation of the photocurrent is caused supposedly by the decrease of the electron affinity due to restructuring in the nonequilibrium cesium overlayer.

Zhuravlev, A. G.; Savchenko, M. L.; Paulish, A. G.; Alperovich, V. L. [Rzhanov Institute of Semiconductor Physics, Lavrentieva, 13, 630090 Novosibirsk, Russia and Novosibirsk State University, Pirogova, 2, 630090 Novosibirsk (Russian Federation); Scheibler, H. E.; Jaroshevich, A. S. [Rzhanov Institute of Semiconductor Physics, Lavrentieva, 13, 630090 Novosibirsk (Russian Federation)

2013-12-04T23:59:59.000Z

300

Ga-assisted catalyst-free growth mechanism of GaAs nanowires by molecular beam epitaxy  

Science Journals Connector (OSTI)

The mechanisms of Ga-assisted GaAs nanowires grown by molecular beam epitaxy are addressed. The axial and radial growth rates as a function of the Ga rate and As pressure indicate that on the opposite of what is observed in thin film epitaxy, the growth rate of the nanowires is arsenic limited. As a consequence, the axial growth rate of the wires can be controlled by the As4 pressure. Additionally, due to the small As4 pressure leading to nanowire growth, the deposition on the facets is very slow, leading to a much lower radial growth rate. Finally, we present a model that is able to accurately describe the presented observations and predicts a maximum length of nontapered nanowires of 40?m.

C. Colombo; D. Spirkoska; M. Frimmer; G. Abstreiter; A. Fontcuberta i Morral

2008-04-28T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" from the National Library of EnergyBeta (NLEBeta).
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301

Calculations of bound and resonant electronic states for the GaAs (111) (2x2) reconstructed surface  

E-Print Network [OSTI]

the degree ol' MASTER OF SCIEVCE December 19ftg Major Subject: Phys)cs CALCULATIONS OF BOUND AiND RESONAiNT ELECTRONIC STATES FOR THE GaAs [111) (2x2) RECONSTRUCTED SURFACE A Thesis by SAMUEL STEPHEiN BLOUNT Approved as to style and content by...), ? 3eV. & E & 2eV 8] (0. 2859, 0. 2268), ? 13eV. & E & ? 8eV. . 82 (0. 2859, 0. 2268). ? 8el'. & E & ? 3eV. . . 83 (0. 2859, 0. 2268), ? 3eV. & E & 2eV. 84 (0. 3569, 0, 2268), ? 13eV ( E & ? 8eV. . 76 (0. 3569, 0. 2268), ? 8eV. & E & ? 3eV. . . 77...

Blount, Samuel Stephen

2012-06-07T23:59:59.000Z

302

Carrier-induced change in refractive index of InP, GaAs, and InGaAsP  

SciTech Connect (OSTI)

The authors have theoretically estimated the change in refractive index {Delta}{ital n} produced by injection of free carriers in InP, GaAs, and InGaAsP. Bandfilling (Burstein-Moss effect), band-gap shrinkage, and free-carrier absorption (plasma effect) were included. Carrier concentrations of 10{sup 16}/cm{sup 3} to 10{sup 19}/cm{sup 3} and photon energies of 0.8 to 2.0 eV were considered. Predictions of {Delta}{ital n} are in reasonably good agreement with the limited experimental data available. Refractive index changes as large as 10{sup {minus} 2} are predicted for carrier concentrations of 10{sup 18}/cm{sup 3}, suggesting that low-loss optical phase modulators and switches using carrier injection are feasible in these materials.

Bennett, B.R. (Dept. of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (US)); Soref, R.A. (Solid State Sciences Directorate, Rome Air Development Center, Hanscom Air Force Base, Bedford, MA (US)); Del Alamo, J.A. (Dept. of Electrical Engineering and Computer Science, Massachussets Institute of Technology, Cambridge, MA (US))

1990-01-01T23:59:59.000Z

303

Electron Transport Behavior on Gate Length Scaling in Sub-50 nm GaAs Metal Semiconductor Field Effect Transistors  

SciTech Connect (OSTI)

Short channel GaAs Metal Semiconductor Field Effect Transistors (MESFETs) have been fabricated with gate length to 20 nm, in order to examine the characteristics of sub-50 nm MESFET scaling. Here the rise in the measured transconductance is mainly attributed to electron velocity overshoot. For gate lengths below 40 nm, however, the transconductance drops suddenly. The behavior of velocity overshoot and its degradation is investigated and simulated by using a transport model based on the retarded Langevin equation (RLE). This indicates the existence of a minimum acceleration length needed for the carriers to reach the overshoot velocity. The argument shows that the source resistance must be included as an internal element, or appropriate boundary condition, of relative importance in any model where the gate length is comparable to the inelastic mean free path of the carriers.

Han, Jaeheon [Department of Electronic Engineering, Kangnam University, 111 Gugal-dong, Giheung-gu, Yongin-city, Gyeonggi-do, Korea 446-702 (Korea, Republic of)

2011-12-23T23:59:59.000Z

304

Investigation of ultrafast photothermal surface expansion and diffusivity in GaAs via laser-induced dynamic gratings  

SciTech Connect (OSTI)

This thesis details the first direct ultrafast measurements of the dynamic thermal expansion of a surface and the temperature dependent surface thermal diffusivity using a two-color reflection transient grating technique. Studies were performed on p-type, n-type, and undoped GaAs(100) samples over a wide range of temperatures. By utilizing a 90 fs ultraviolet probe with visible excitation beams, the effects of interband saturation and carrier dynamics become negligible; thus lattice expansion due to heating and subsequent contraction caused by cooling provided the dominant influence on the probe. At room temperature a rise due to thermal expansion was observed, corresponding to a maximum net displacement of {approximately} 1 {Angstrom} at 32 ps. The diffracted signal was composed of two components, thermal expansion of the surface and heat flow away from the surface, thus allowing a determination of the rate of expansion as well as the surface thermal diffusivity, D{sub S}. By varying the fringe spacing of the grating, this technique has the potential to separate the signal contributions to the expansion of the lattice in the perpendicular and parallel directions. In the data presented here a large fringe spacing was used, thus the dominant contribution to the rising edge of the signal was expansion perpendicular to the surface. Comparison of he results with a straightforward thermal model yields good agreement over a range of temperatures (20--300{degrees}K). Values for D{sub S} in GaAs were measured and found to be in reasonable agreement with bulk values above 50{degrees}K. Below 50{degrees}K, D{sub S} were determined to be up to an order of magnitude slower than the bulk diffusivity due to increased phonon boundary scattering. The applicability and advantages of the TG technique for studying photothermal and photoacoustic phenomena are discussed.

Pennington, D.M.

1992-04-01T23:59:59.000Z

305

Monolithically interconnected GaAs solar cells: A new interconnection technology for high voltage solar cell output  

SciTech Connect (OSTI)

Photovoltaic linear concentrator arrays can benefit from high performance solar cell technologies being developed at AstroPower. Specifically, these are the integration of thin GaAs solar cell and epitaxial lateral overgrowth technologies with the application of monolithically interconnected solar cell (MISC) techniques. This MISC array has several advantages which make it ideal for space concentrator systems. These are high system voltage, reliable low cost monolithically formed interconnections, design flexibility, costs that are independent of array voltage, and low power loss from shorts, opens, and impact damage. This concentrator solar cell will incorporate the benefits of light trapping by growing the device active layers over a low-cost, simple, PECVD deposited silicon/silicon dioxide Bragg reflector. The high voltage-low current output results in minimal 12R losses while properly designing the device allows for minimal shading and resistance losses. It is possible to obtain open circuit voltages as high as 67 volts/cm of solar cell length with existing technology. The projected power density for the high performance device is 5 kW/m for an AMO efficiency of 26% at 1 5X. Concentrator solar cell arrays are necessary to meet the power requirements of specific mission platforms and can supply high voltage power for electric propulsion systems. It is anticipated that the high efficiency, GaAs monolithically interconnected linear concentrator solar cell array will enjoy widespread application for space based solar power needs. Additional applications include remote man-portable or ultra-light unmanned air vehicle (UAV) power supplies where high power per area, high radiation hardness and a high bus voltage or low bus current are important. The monolithic approach has a number of inherent advantages, including reduced cost per interconnect and increased reliability of array connections. There is also a high potential for a large number of consumer products.

Dinetta, L.C.; Hannon, M.H.

1995-10-01T23:59:59.000Z

306

Functional materials: electronics, information and sensors  

Science Journals Connector (OSTI)

Functional materials are those that have properties enabling them to preform a specific functional purpose, e.g. electrical, magnetic or optical. The rapid development of the technology of transistors and intergrated circuits will continue into the future with design incorporating new materials, notably gallium arsenide. Silica glass is finding increasing application in photonics, light emitting diodes and optical fibres for telephone cables. Optical-fibre technology depends on reliable and durable lasers which now use compound semiconductors such as indium-gallium-arsenide phosphide. It is anticipated that new materials application (indium-gallium-arsenide phosphide) will contribute towards progress in photovoltaics. Interest in superconducting material has heightened during 1980s with the promise that high-temperature superconductivity offers for more-efficient power generation and transmission. In future advantage will come from developing economic and reliable ways of producing functional materials to meet increasing demand.

Merton C. Flemings

1990-01-01T23:59:59.000Z

307

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

308

Hort-Range Wetting at Liquid Gallium-Bismuth Alloy Surfaces: X-ray Measurements and Square-Gradient Theory  

SciTech Connect (OSTI)

We present an x-ray reflectivity study of wetting at the free surface of the binary liquid metal alloy gallium-bismuth (Ga-Bi) in the region where the bulk phase separates into Bi-rich and Ga-rich liquid phases. The measurements reveal the evolution of the microscopic structure of the wetting films of the Bi-rich, low-surface-tension phase along several paths in the bulk phase diagram. The wetting of the Ga-rich bulk's surface by a Bi-rich wetting film, the thickness of which is limited by gravity to only 50 Angstroms, creates a Ga-rich/Bi-rich liquid/liquid interface close enough to the free surface to allow its detailed study by x rays. The structure of the interface is determined with Angstromsngstrem resolution, which allows the application of a mean-field square gradient model extended by the inclusion of capillary waves as the dominant thermal fluctuations. The sole free parameter of the gradient model, the influence parameter K, that characterizes the influence of concentration gradients on the interfacial excess energy, is determined from our measurements. This, in turn, allows a calculation of the liquid/liquid interfacial tension, and a separation of the intrinsic and capillary wave contributions to the interfacial structure. In spite of expected deviations from MF behavior, based on the upper critical dimensionality (Du = 3 ) of the bulk, we find that the capillary wave excitations only marginally affect the short-range complete wetting behavior. A critical wetting transition that is sensitive to thermal fluctuations appears to be absent in this binary liquid-metal alloy.

Huber, P.; Shpyrko, O; Pershan, P; Ocko, B; DiMasi, E; Deutsch, M

2009-01-01T23:59:59.000Z

309

Photoacoustic signals of n-type GaAs layers grown by molecular-beam epitaxy on semi-insulating substrates  

Science Journals Connector (OSTI)

Piezoelectric photoacoustic (PA) measurements of molecular-beam-epitaxial (MBE) -grown GaAs layers were carried out in the temperature range from 90 to 290 K. A broad D band with a maximum near 1.3 eV and a sharp Q peak at 1.485 eV have been observed in the 90-K spectra. They vanish in a presence of secondary light illumination. By comparing with optical-absorption spectra, it is considered that the D band is due to electron transitions involving EL2 deep defect levels in the GaAs substrate. The PA signal is considered to be enhanced by the presence of the electric field at the interface between the MBE layer and the substrate. The Q peak is attributed to electron transitions from shallow acceptors such as carbon in GaAs. Observed photoinduced changes in the spectra are explained by a reduction of the electric field in the depletion region which is induced by optical carrier generation.

T. Ikari; A. Fukuyama; K. Maeda; K. Futagami; S. Shigetomi; Y. Akashi

1992-10-15T23:59:59.000Z

310

Ion exchange separation of plutonium and gallium (1) resource and inventory requirements, (2) waste, emissions, and effluent, and (3) facility size  

SciTech Connect (OSTI)

The following report summarizes an effort intended to estimate within an order-of-magnitude the (1) resource and inventory requirements, (2) waste, emissions, and effluent amounts, and (3) facility size, for ion exchange (IX) separation of plutonium and gallium. This analysis is based upon processing 3.5 MT-Pu/yr. The technical basis for this summary is detailed in a separate document, {open_quotes}Preconceptual Design for Separation of Plutonium and Gallium by Ion Exchange{close_quotes}. The material balances of this separate document are based strictly on stoichiometric amounts rather than details of actual operating experience, in order to avoid classification as Unclassified Controlled Nuclear Information. This approximation neglets the thermodynamics and kinetics which can significantly impact the amount of reagents required. Consequently, the material resource requirements and waste amounts presented here would normally be considered minimums for processing 3.5 MT-Pu/yr; however, the author has compared the inventory estimates presented with that of an actual operating facility and found them similar. Additionally, the facility floor space presented here is based upon actual plutonium processing systems and can be considered a nominal estimate.

DeMuth, S.

1997-09-30T23:59:59.000Z

311

Exciton-exciton and exciton-phonon interactions in an interfacial GaAs quantum dot ensemble  

Science Journals Connector (OSTI)

Using optical two-dimensional Fourier transform spectroscopy, we report temperature- and excitation-density-dependent measurements of the homogeneous linewidth of the exciton ground-state transition in a single layer of interfacial GaAs quantum dots (QDs). We show that the homogeneous linewidth increases nonlinearly with temperature from 6 to 50 K and that the thermal broadening is well described by an activation term and offset. The absence of a phonon-activation peak in the two-dimensional spectra reveals that elastic scattering of excitons with acoustic phonons via virtual transitions between the ground and excited states significantly contributes to the thermal broadening. We find that the combination of increasing virtual activation energy and exciton-phonon coupling strength with decreasing QD size results in greater thermal broadening for excitons localized in smaller QDs. The homogeneous linewidth also exhibits a strong excitation-density dependence and is shown to increase linearly as the photon density increases from 2×1011 to 1×1012 photons pulse-1 cm-2 at 6 K. This trend is attributed to strong coupling of excitons within the same QD and is independent of the quantum-well exciton population density.

G. Moody; M. E. Siemens; A. D. Bristow; X. Dai; D. Karaiskaj; A. S. Bracker; D. Gammon; S. T. Cundiff

2011-03-23T23:59:59.000Z

312

A critical discussion of emission mechanisms and reaction rates for the ion?assisted etching of GaAs(100)  

Science Journals Connector (OSTI)

Emission mechanisms and reaction rates for the ion?assisted etching of GaAs(100) have been studied in detail using energetic argon ions and chlorine gas. Ion energies of 500 and 1000 eV were used with chlorine/argon ion surface?flux ratios of 1–120. The m a j o r molecular etchant products were found to be GaCl2 and AsCl3. Gas phase products were detected at different flight distances to investigate the nature of surface residence times. It is concluded based on these measurements that GaCl2 emission is best interpreted in terms of the collisional?cascade sputteringmodel for the specific range of ion energies and surface?flux ratios studied. Using a similar analysis it is concluded that AsCl3 may be emitted by either the thermal desorption or the collisional?cascade mechanisms with the former favored in the range of higher surface?flux ratios and lower ion energies. Furthermore the thermal desorption of AsCl3 appears to follow a first?order surface process. Comparison of our data with those of others indicates general agreement. However more extended analysis based on a broader and more intensive data base leads to some important distinctions among the final conclusions regarding the emission mechanisms.

W. L. O’Brien; C. M. Paulsen?Boaz; T. N. Rhodin; L. C. Rathbun

1988-01-01T23:59:59.000Z

313

Deep Levels in p-Type InGaAsN Lattice Matched to GaAs  

SciTech Connect (OSTI)

Deep level transient spectroscopy (DLTS) measurements were utilized to investigate deep level defects in metal-organic chemical deposition (MOCVD)-grown unintentionally doped p-type InGaAsN films lattice matched to GaAs. The as-grown material displayed a high concentration of deep levels distributed within the bandgap, with a dominant hole trap at E{sub v} + 0.10 eV. Post-growth annealing simplified the deep level spectra, enabling the identification of three distinct hole traps at 0.10 eV, 0.23 eV, and 0.48 eV above the valence band edge, with concentrations of 3.5 x 10{sup 14} cm{sup {minus}3}, 3.8 x 10{sup 14} cm{sup {minus}3}, and 8.2 x 10{sup 14} cm{sup {minus}3}, respectively. A direct comparison between the as-grown and annealed spectra revealed the presence of an additional midgap hole trap, with a concentration of 4 x 10{sup 14} cm{sup {minus}3} in the as-grown material. The concentration of this trap is sharply reduced by annealing, which correlates with improved material quality and minority carrier properties after annealing. Of the four hole traps detected, only the 0.48 eV level is not influenced by annealing, suggesting this level may be important for processed InGaAsN devices in the future.

Allerman, A.A.; Jones, E.D.; Kaplar, R.J.; Kurtz, S.R.; Kwon, D.; Ringel, S.A.

1999-03-02T23:59:59.000Z

314

Selfsimilar and fractal analysis of n-type delta-doped quasiregular GaAs quantum wells  

SciTech Connect (OSTI)

We study the electronic structure of n-type delta-doped quantum wells in GaAs in which the multiple well system is built according to the Fibonacci sequence. The building blocks A and B correspond to delta-doped wells with impurities densities n{sub 2DA} and n{sub 2DB}, and the same well width. The Thomas-Fermi approximation, the semi-empirical sp{sub 3}s* tight-binding model including spin, the Surface Green Function Matching method and the Transfer Matrix approach were implemented to obtain the confining potential, the electronic structure and the selfsimilarity of the spectrum. The fragmentation of the electronic spectra is observed whenever the building blocks A and B interact and it increases as the difference of impurities density between A and B increases as well. The wave function of the first sate of the fragmented bands presents critical characteristics, this is, it is not a localized state nor a extended one as well as it has selfsimilar features. So, the quasiregular characteristics are preserved irrespective of the complexity of the system and can affect the performance of devices based on these structures.

García-Cervantes, H.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)

2014-05-15T23:59:59.000Z

315

Surface Micromachined Components for a Safety Subsystem Application  

SciTech Connect (OSTI)

We have designed and fabricated a system using micromachining technologies that represents the first phase of an effort to develop a miniaturized or micro trajectory safety subsystem. Two Surface Micromachined (SMM) devices have been fabricated. The first is a device, denoted the Shuttle Mechanism, that contains a suspended shuttle that has a unique code imbedded in its surface. The second is a mechanical locking mechanism, denoted a Stronglink, that uses the code imbedded in the Shuttle Mechanism for unlocking. The Stronglink is designed to block a beam of optical energy until unlocked. A Photonic Integrated Circuit (PIC) fabricated in Gallium Arsenide (GaAs) and an ASIC have been designed to read the code contained in the Shuttle Mechanism. The ASIC interprets the data read by the PIC and outputs low-level drive signals for the actuators used by the Stronglink. An off-chip circuit amplifies the drive signals. Once the Stronglink is unlocked, a laser array that is assembled beneath the device is energized and light is transmitted through an aperture.

Garcia, E.J.; Holswade, S.; Plummer, D.W.; Polosky, M.A.; Shul, R.J.; Sulivan, C.T.

1999-03-04T23:59:59.000Z

316

Imaging of semiconductors using a flying laser spot scanning system  

E-Print Network [OSTI]

be obsezved in the wavelength vs. absorption coefficient curves shown in Figure 1 for both a direct and an indirect semiconductor material (gallium-arsenide and silicon). It is only in the direct absorption and subsequent generation of a hole electron pair... in wavelength of light used to generate carriers pro- vides some contzol over the depth of the material analyzed. Long wavelength energy (- 1 micrometer) penetrates deeply into silicon, while gallium phosphide is considered almost transparent for a typical...

Richardson, Thomas William

2012-06-07T23:59:59.000Z

317

Laser-Driven Growth of Silver Nanoplates on p-Type GaAs Substrates and Their Surface-Enhanced Raman Scattering Activity  

Science Journals Connector (OSTI)

Laser-Driven Growth of Silver Nanoplates on p-Type GaAs Substrates and Their Surface-Enhanced Raman Scattering Activity ... Each wafer was cut into ?1 cm × 1 cm square pieces along their cleavage planes (i.e., [01?1?] and [01?1]) and were cleaned by immersing them in a 2% hydrofluoric acid (HF) aqueous solution (Fisher) for 5 min. ... Continued growth smoothes the stepped edges of the oligomers and fuses them into thicker nanoplates whose thicknesses are approximately equal to the sum of the individual plate thicknesses before fusion (Figure 5c). ...

Yugang Sun; Matthew Pelton

2009-03-20T23:59:59.000Z

318

Magneto-transport properties of InAs nanowires laterally-grown by selective area molecular beam epitaxy on GaAs (110) masked substrates  

SciTech Connect (OSTI)

We prepared InAs nanowires (NWs) by lateral growth on GaAs (110) masked substrates in molecular beam epitaxy. We measured magneto-transport properties of the InAs NWs. In spite of parallel-NW multi-channels, we observed fluctuating magneto-conductance. From the fluctuation, we evaluated phase coherence length as a function of measurement temperature, and found decrease in the length with increase in the temperature. We also evaluate phase coherence length as a function of gate voltage.

Akabori, M.; Yamada, S. [Center for Nano-Materials and Technology, Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa 923-1292 (Japan)

2013-12-04T23:59:59.000Z

319

Observation and Measurement of Temperature Rise and Distribution on GaAs Photo-cathode Wafer with a 532nm Drive Laser and a Thermal Imaging Camera  

SciTech Connect (OSTI)

Significant temperature rise and gradient are observed from a GaAs photo-cathode wafer irradiated at various power levels with over 20W laser power at 532nm wavelength. The laser power absorption and dissipated thermal distribution are measured. The result shows a clear indication that proper removal of laser induced heat from the cathode needs to be considered seriously when designing a high average current or low quantum efficiency photo-cathode electron gun. The measurement method presented here provides a useful way to obtain information about both temperature and thermal profiles, it also applies to cathode heating study with other heating devices such as electrical heaters.

Shukui Zhang, Stephen Benson, Carlos Hernandez-Garcia

2011-03-01T23:59:59.000Z

320

U.S. GEOLOGICAL SURVEY--MINERALS INFORMATION 1 By Deborah A. Kramer  

E-Print Network [OSTI]

). to produce optoelectronic devices and integrated circuits for Increased demand for GaAs resulted in several U. Consumption Optoelectronic devices continued to be the largest end use for gallium, with 59% of total

Note: This page contains sample records for the topic "gallium arsenide gaas" from the National Library of EnergyBeta (NLEBeta).
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321

JOURNALDE PHYSIQUEIV Colloque C1, supplkmentau Journal de Physique 111,Volume 5,janvier 1995  

E-Print Network [OSTI]

that occur naturally in semi-insulating (SI) Gallium arsenide. The growth and assessment of SI Ga process which is by radiation and convection of heat from the crystal surface into the ambient. The former is uncontrolled as the radiation takes place into a cool chamber; the latter is controllable to an extent

Boyer, Edmond

322

Friday, May 21, 2010 High-Performance Electronics without the High Price  

E-Print Network [OSTI]

materials. Researchers have used the method to make high-performance image sensors, transistors, and solar exotic semiconductors brings down the cost of high- performance solar cells and microchips. By Katherine Bourzac Compared to silicon, semiconductors like gallium arsenide can be made into solar cells

Rogers, John A.

323

Phytochrome induces changes in the immunodetectable level of a wall peroxidase that precede growth changes in maize seedlings  

Science Journals Connector (OSTI)

...the 20-min distilled water rinse, the light-treated...with a 3 x 8 array of gallium aluminum arsenide infrared light (IR...loading and distilled water rinse. Sections were...the binding state or solubility of the peroxidase could...

Sung-Ha Kim; James R. Shinkle; Stanley J. Roux

1989-01-01T23:59:59.000Z

324

Corrosion of Electronic Materials and Devices  

Science Journals Connector (OSTI)

...ranging from silicon to gallium arsenide to mercury cadmium...protected against are water vapor and atmospheric...amount of adsorbed water on the surface...several monolayers of water are present on clean...reactivity with or solubility in the existing surface...

R. B. COMIZZOLI; R. P. FRANKENTHAL; P. C. MILNER; J. D. SINCLAIR

1986-10-17T23:59:59.000Z

325

Anomalous Properties of Poly(methyl methacrylate) Thin Films in Supercritical Carbon Dioxide  

Science Journals Connector (OSTI)

The PMMA swelling isotherms are insensitive to changing the substrate from silicon to gallium arsenide. ... The wafers were then rinsed with voluminous amounts of deionized water (NANOpureII, Barnstead) and then dried with nitrogen gas (Matheson Gas Products, >99.999%). ... The solubility of CO2 in the polymer film may be expected to decrease as the compressibility increases. ...

S. M. Sirard; K. J. Ziegler; I. C. Sanchez; P. F. Green; K. P. Johnston

2002-02-01T23:59:59.000Z

326

Persistent exciton-type many-body interactions in GaAs quantum wells measured using two-dimensional optical spectroscopy  

Science Journals Connector (OSTI)

Studies have shown that many-body interactions among semiconductor excitons can produce distinct features in two-dimensional optical spectra. However, to the best of our knowledge, the dynamics of many-body interactions have not been measured in two-dimensional (2D) spectroscopy studies. Here we measure 2D spectra of GaAs quantum wells at many different “waiting” times and study the time dependence of the spectral features. Characteristic signatures of exciton polarization correlations manifest in the diagonal peaks decay at the exciton dephasing rate, consistent with theoretical predictions. Other many-body interactions manifest in off-diagonal features decay much more slowly. These persistent off-diagonal features must be due to many-body interactions involving exciton populations, and their persistence cannot be predicted by theoretical descriptions restricted to the coherent limit.

Daniel B. Turner; Patrick Wen; Dylan H. Arias; Keith A. Nelson; Hebin Li; Galan Moody; Mark E. Siemens; Steven T. Cundiff

2012-05-15T23:59:59.000Z

327

Critical size for the generation of misfit dislocations and their effects on electronic properties in GaAs nanosheets on Si substrate  

SciTech Connect (OSTI)

While nanowires and nanosheets (NSs) grown on lattice-mismatched substrates have a number of promising technological applications such as solar cells, generation of misfit dislocations (MFDs) at their interfaces is a major concern for the efficiency of these devices. Here, combined molecular-dynamics and quantum-mechanical simulations are used to study MFDs at the interface between a GaAs NS and a Si substrate. Simulation results show the existence of a critical NS thickness, below which NSs are grown free of MFDs. The calculated critical thickness value is consistent with available experimental observations. Charge transfer at the MFD core is found to modify the electronic band profile at the GaAs/Si interface significantly. These effects should have profound impacts on the efficiency of lattice-mismatched NS devices.

Yuan, Zaoshi [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025 (United States); Shimamura, Kohei [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Shimojo, Fuyuki [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)] [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

2013-08-21T23:59:59.000Z

328

InGaAs heterostructure formation in catalyst-free GaAs nanopillars by selective-area metal-organic vapor phase epitaxy  

SciTech Connect (OSTI)

We investigate axial GaAs/InGaAs/GaAs heterostructures embedded in GaAs nanopillars via catalyst-free selective-area metal-organic chemical vapor deposition. Structural characterization by transmission electron microscopy with energy dispersive x-ray spectroscopy (EDS) indicates formation of axial In{sub x}Ga{sub 1-x}As (x{approx}0.20) inserts with thicknesses from 36 to 220 nm with {+-}10% variation and graded Ga:In transitions controlled by In segregation. Using the heterointerfaces as markers, the vertical growth rate is determined to increase linearly during growth. Photoluminescence from 77 to 290 K and EDS suggest the presence of strain in the shortest inserts. This capability to control the formation of axial nanopillar heterostructures is crucial for optimized device integration.

Shapiro, J. N.; Lin, A.; Wong, P. S.; Scofield, A. C.; Tu, C.; Senanayake, P. N.; Mariani, G.; Liang, B. L.; Huffaker, D. L. [Department of Electrical Engineering and California Nano-Systems Institute, University of California at Los Angeles, Los Angeles, California 90095 (United States)

2010-12-13T23:59:59.000Z

329

Infrared spectroscopy of lattice vibrations in ZnTe/CdTe superlattices with quantum dots on the GaAs substrate with the ZnTe buffer layer  

SciTech Connect (OSTI)

The results of the analysis of the infrared lattice reflectance spectra of multiperiod ZnTe/CdTe superlattices with CdTe quantum dots are reported. The samples are grown by molecular beam epitaxy on the GaAs substrate with the ZnTe buffer layer. Due to the large number of periods of the superlattices, it is possible to observe CdTe-like vibration modes in the quantum dots, i.e., the dislocation-free stressed islands formed during the growth due to relaxation of elastic stresses between the ZnTe and CdTe layers are markedly different in their lattice parameters. From the frequency shifts of the CdTe- and ZnTe-like vibration modes with respect to the corresponding modes in the unstressed materials, it is possible to estimate the level of elastic stresses.

Kozyrev, S. P. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)], E-mail: skozyrev@sci.lebedev.ru

2009-03-15T23:59:59.000Z

330

Polarity driven simultaneous growth of free-standing and lateral GaAsP epitaxial nanowires on GaAs (001) substrate  

SciTech Connect (OSTI)

Simultaneous growth of ?111?{sub B} free-standing and ±[110] lateral GaAsP epitaxial nanowires on GaAs (001) substrates were observed and investigated by electron microscopy and crystallographic analysis. It was found that the growth of both free-standing and lateral ternary nanowires via Au catalysts was driven by the fact that Au catalysts prefer to maintain low-energy (111){sub B} interfaces with surrounding GaAs(P) materials: in the case of free-standing nanowires, Au catalysts maintain (111){sub B} interfaces with their underlying GaAsP nanowires; while in the case of lateral nanowires, each Au catalyst remain their side (111){sub B} interfaces with the surrounding GaAs(P) material during the lateral nanowire growth.

Sun, Wen; Xu, Hongyi [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia)] [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia); Guo, Yanan [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia) [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia); Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Gao, Qiang; Hoe Tan, Hark; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)] [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Zou, Jin, E-mail: j.zou@uq.edu.au [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia) [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia); Centre for Microscopy and Microanalysis, The University of Queensland, St Lucia QLD 4072 (Australia)

2013-11-25T23:59:59.000Z

331

Importance of carrier dynamics and conservation of momentum in atom-selective STM imaging and band gap determination of GaAs(110)  

Science Journals Connector (OSTI)

Scanning tunneling microscopy and spectroscopy measurements on the GaAs(110) surface with complementary theoretical calculations are performed to clarify the effects involved in the tunneling of unpinned semiconductor surfaces. We show that the flatband and tip-induced band bending as well as equilibrium conditions are insufficient to describe the effects involved. Instead, carrier dynamics and conservation of momentum of the tunneling electrons need to be taken into account for a complete description of the contributions of the valence or conduction band states. The results allow us to understand the unique properties needed to achieve the atom-selective imaging observed on these surfaces as well as the determination of the band gap energy.

N. D. Jäger, E. R. Weber, K. Urban, and Ph. Ebert

2003-04-29T23:59:59.000Z

332

but the resolution of 2 was not sufficient to determine whether the C18  

E-Print Network [OSTI]

but the resolution of 2 was not sufficient to determine whether the C18 O emission was con- fined and AUI for funding the PT link project and to Western New Mexico Telephone Company for the use arsenide (GaAs) without losing their polar- ization, so that coherent transport through the active region

Thibado, Paul M.

333

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

334

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

335

Imaging with Mass Spectrometry: A SIMS and VUV-Photoionization Study of Ion-Sputtered Atoms and Clusters from GaAs and Au  

SciTech Connect (OSTI)

A new mass spectrometry surface imaging method is presented in which ion-sputtered neutrals are postionized by wavelength-tunable vacuum ultraviolet (VUV) light from a synchrotron source. Mass spectra and signal counts of the photoionized neutrals from GaAs (100) and Au are compared to those of the secondary ions. While clusters larger than dimers are more efficiently detected as secondary ions, certain species, such as As2, Au and Au2, are more efficiently detected through the neutral channel. Continuously tuning the photon wavelength allows photoionization efficiency (PIE) curves to be obtained for sputtered Asm (m=1,2) and Aun (n=1-4). From the observed ionization thresholds, sputtered neutral As and Au show no clear evidence of electronic excitation, while neutral clusters have photoionization onsets shifted to lower energies by ~;;0.3 eV. These shifts are attributed to unresolved vibrational and rotational excitations. High-spatial resolution chemical imaging with synchrotron VUV postionization is demonstrated at two different photon energies using a copper TEM grid embedded in indium. The resulting images are used to illustrate the use of tunable VUV light for verifying mass peak assignments by exploiting the unique wavelength-dependent PIE of each sputtered neutral species. This capability is valuable for identifying compounds when imaging chemically complex systems with mass spectrometry-based techniques.

Takahashi, Lynelle; Zhou, Jia; Wilson, Kevin R.; Leone, Stephen R.; Ahmed, Musahid

2008-12-05T23:59:59.000Z

336

Relation between the metastability of EL2 and the photosensitivity of local vibrational modes in semi-insulating GaAs  

Science Journals Connector (OSTI)

Recent infrared spectroscpic observations of local vibrational mode absorptions have revealed a number of photosensitive centers in semi-insulating GaAs. They include (OVAs) center which has three modes at 730 cm-1 (A), 715 cm-1 (B), and 714 cm-1 (C), respectively, a suggested NH center related to a line at 983 cm-1 (X1), and centers related to hydrogen, such as (H-O) or (H-N) bonds, corresponding to a group of peaks in the region of 2900–3500 cm-1. The photosensitivity of various local vibration centers was observed to have similar time dependence under near-infrared illumination and was suggested to be due to their charge-state interconversion. Mainly described in this work is the effect of the 1.25-eV illumination. It is confirmed that this photoinduced kinetic process results from both electron capture and hole capture, which are closely related to the photoionization behavior and metastability of the EL2 center.

C. Y. Song, B. Pajot, W. K. Ge, and D. S. Jiang

1995-08-15T23:59:59.000Z

337

Wafer Bonding and Epitaxial Transfer of GaSb-based Epitaxy to GaAs for Monolithic Interconnection of Thermophotovoltaic Devices  

SciTech Connect (OSTI)

GaInAsSb/AlGaAsSb/InAsSb/GaSb epitaxial layers were bonded to semi-insulating GaAs handle wafers with SiO{sub x}/Ti/Au as the adhesion layer for monolithic interconnection of thermophotovoltaic (TPV) devices. Epitaxial transfer was completed by removal of the GaSb substrate, GaSb buffer, and InAsSb etch-stop layer by selective chemical etching. The SiO{sub x}/TiAu provides not only electrical isolation, but also high reflectivity and is used as an internal back-surface reflector. Characterization of wafer-bonded epitaxy by high-resolution x-ray diffraction and time-decay photoluminescence indicates minimal residual stress and enhancement in optical quality. 0.54-eV GaInAsSb cells were fabricated and monolithically interconnected in series. A 10-junction device exhibited linear voltage building with an open-circuit voltage of 1.8 V.

C.A. Wang; D.A. Shiau; P.G. Murphy; P.W. O'brien; R.K. Huang; M.K. Connors; A.C. Anderson; D. Donetsky; S. Anikeev; G. Belenky; D.M. Depoy; G. Nichols

2003-06-16T23:59:59.000Z

338

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

339

Measurement of the solar neutrino capture rate with gallium metal. III: Results for the 2002--2007 data-taking period  

E-Print Network [OSTI]

The Russian-American experiment SAGE began to measure the solar neutrino capture rate with a target of gallium metal in Dec. 1989. Measurements have continued with only a few brief interruptions since that time. We give here the experimental improvements in SAGE since its last published data summary in Dec. 2001. Assuming the solar neutrino production rate was constant during the period of data collection, combined analysis of 168 extractions through Dec. 2007 gives a capture rate of solar neutrinos with energy more than 233 keV of 65.4 (+3.1)(-3.0) (stat) (+2.6)(-2.8) (syst) SNU. The weighted average of the results of all three Ga solar neutrino experiments, SAGE, Gallex, and GNO, is now 66.1 +/- 3.1 SNU, where statistical and systematic uncertainties have been combined in quadrature. During the recent period of data collection a new test of SAGE was made with a reactor-produced 37Ar neutrino source. The ratio of observed to calculated rates in this experiment, combined with the measured rates in the three prior 51Cr neutrino-source experiments with Ga, is 0.87 +/- 0.05. A probable explanation for this low result is that the cross section for neutrino capture by the two lowest-lying excited states in 71Ge has been overestimated. If we assume these cross sections are zero, then the standard solar model including neutrino oscillations predicts a total capture rate in Ga in the range of 63-66 SNU with an uncertainty of about 4%, in good agreement with experiment. We derive the current value of the neutrino flux produced in the Sun by the proton-proton fusion reaction to be (6.0 +/- 0.8) x 10^(10)/(cm^2 s), which agrees well with the pp flux predicted by the standard solar model. Finally, we show that the data are consistent with the assumption that the solar neutrino production rate is constant in time.

SAGE Collaboration; J. N. Abdurashitov; V. N. Gavrin; V. V. Gorbachev; P. P. Gurkina; T. V. Ibragimova; A. V. Kalikhov; N. G. Khairnasov; T. V. Knodel; I. N. Mirmov; A. A. Shikhin; E. P. Veretenkin; V. E. Yants; G. T. Zatsepin; T. J. Bowles; S. R. Elliott; W. A. Teasdale; J. S. Nico; B. T. Cleveland; J. F. Wilkerson

2009-01-15T23:59:59.000Z

340

Structural and band alignment properties of Al{sub 2}O{sub 3} on epitaxial Ge grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy  

SciTech Connect (OSTI)

Structural and band alignment properties of atomic layer Al{sub 2}O{sub 3} oxide film deposited on crystallographically oriented epitaxial Ge grown in-situ on (100), (110), and (111)A GaAs substrates using two separate molecular beam epitaxy chambers were investigated using cross-sectional transmission microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). High-resolution triple axis x-ray measurement demonstrated pseudomorphic and high-quality Ge epitaxial layer on crystallographically oriented GaAs substrates. The cross-sectional TEM exhibited a sharp interface between the Ge epilayer and each orientation of the GaAs substrate as well as the Al{sub 2}O{sub 3} film and the Ge epilayer. The extracted valence band offset, {Delta}E{sub v}, values of Al{sub 2}O{sub 3} relative to (100), (110), and (111) Ge orientations using XPS measurement were 3.17 eV, 3.34 eV, and 3.10 eV, respectively. Using XPS data, variations in {Delta}E{sub v} related to the crystallographic orientation were {Delta}E{sub V}(110)Ge>{Delta}E{sub V}(100)Ge{>=}{Delta}E{sub V}(111)Ge and the conduction band offset, {Delta}E{sub c}, related to the crystallographic orientation was {Delta}E{sub c}(111)Ge>{Delta}E{sub c}(110)Ge>{Delta}E{sub c}(100)Ge using the measured {Delta}E{sub v}, bandgap of Al{sub 2}O{sub 3} in each orientation, and well-known Ge bandgap of 0.67 eV. These band offset parameters are important for future application of Ge-based p- and n-channel metal-oxide field-effect transistor design.

Hudait, M. K.; Zhu, Y. [Advanced Devices and Sustainable Energy Laboratory (ADSEL), 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); Patra, P. K. [Department of Biomedical Engineering and Department of Mechanical Engineering, University of Bridgeport, Bridgeport, Connecticut 06604 (United States); Ma, A. W. K. [Department of Chemical and Biomolecular Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Aphale, A.; Macwan, I. [Department of Electrical and Computer Engineering, University of Bridgeport, Bridgeport, Connecticut 06604 (United States)

2013-04-07T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Direct exchange interaction of localized spins associated with unpaired sp electrons in Be-doped low-temperature-grown GaAs layers  

SciTech Connect (OSTI)

Beryllium-doped GaAs layers grown at low temperatures by molecular-beam epitaxy contain localized spins associated with unpaired sp electrons of As{sub Ga}{sup +} ions. Interactions of these localized spins are investigated by measuring the magnetization with a superconducting quantum interference device and the peak-to-peak width of electron paramagnetic resonance (EPR) spectra for samples with different spin concentrations ranging from 3 x 10{sup 18} to 2.0 x 10{sup 19} cm{sup -3}. The results show that localized spins in this material antiferromagnetically interact on each other via direct exchange. From the analysis of the temperature dependence and field dependence of the magnetization on the basis of the Curie-Weiss law and the molecular-field approximation, exchange energy of each sample was derived. The dependence of the exchange energy on the concentration of localized spins is reasonably explained by a model of direct exchange, which results from the overlapping of wave functions of unpaired electrons at As{sub Ga}{sup +} ions. The peak-to-peak width of EPR spectra increases with an increase in the spin concentration at low temperatures, whereas it decreases with an increase in the temperature for samples with high spin concentrations. These EPR results also show that significant exchange interactions indeed occur between localized spins in this material. These effects of direct exchange interactions between localized spins can clearly be observed at their average distances of around 4 nm, which implies a considerably large spatial extension of the wave function of an unpaired sp electron around an As{sub Ga}{sup +} ion.

Bae, K. W.; Mohamed, Mohd Ambri; Jung, D. W.; Otsuka, N. [School of Materials Science Japan Advanced Institute of Science and Technology Asahidai 1-1, Nomishi, Ishikawa 923-1292 (Japan)

2011-04-01T23:59:59.000Z

342

Structural ordering and interface morphology in symmetrically strained(GaIn)As/Ga(PAs) superlattices grown on off-oriented GaAs(100)  

Science Journals Connector (OSTI)

In this work we investigate the structural properties of symmetrically strained (GaIn)As/GaAs/Ga(PAs)/GaAs superlattices by means of x-ray diffraction, reciprocal-space mapping, and x-ray reflectivity. The multilayers were grown by metalorganic vapor-phase epitaxy on (001) GaAs substrates intentionally off-oriented towards one of the nearest ?110? directions. High-resolution triple-crystal reciprocal-space maps recorded for different azimuth angles in the vicinity of the (004) Bragg diffraction clearly show a double periodicity of the x-ray peak intensity that can be ascribed to a lateral and a vertical periodicity occurring parallel and perpendicular to the growth surface. Moreover, from the intensity modulation of the satellite peaks, a lateral-strain gradient within the epilayer unit cell is found, varying from a tensile to a compressive strain. Thus, the substrate off-orientation promotes a lateral modulation of the layer thickness (ordered interface roughness) and of the lattice strain, giving rise to laterally ordered macrosteps. In this respect, contour maps of the specular reflected beam in the vicinity of the (000) reciprocal lattice point were recorded in order to inspect the vertical and lateral interface roughness correlation. A semiquantitative analysis of our results shows that the interface morphology and roughness is greatly influenced by the off-orientation angle and the lateral strain distribution. Two mean spatial wavelengths can be determined, one corresponding exactly to the macrostep periodicity and the other indicating a further interface waviness along the macrosteps. The same spatial periodicities were found on the surface by atomic-force-microscopy images confirming the x-ray results and revealing a strong vertical correlation of the interfaces up to the outer surface.

C. Giannini; L. Tapfer; Y. Zhuang; L. De Caro; T. Marschner; W. Stolz

1997-02-15T23:59:59.000Z

343

IR spectroscopy of lattice vibrations and comparative analysis of the ZnTe/CdTe quantum-dot superlattices on the GaAs substrate and with the ZnTe and CdTe buffer layers  

SciTech Connect (OSTI)

A comparative analysis of multiperiod ZnTe/CdTe superlattices with the CdTe quantum dots grown by molecular beam epitaxy on the GaAs substrate with the ZnTe and CdTe buffer layers is carried out. The elastic-stress-induced shifts of eigenfrequencies of the modes of the CdTe- and ZnTe-like vibrations of materials forming similar superlattices but grown on different buffer ZnTe and CdTe layers are compared. The conditions of formation of quantum dots in the ZnTe/CdTe superlattices on the ZnTe and CdTe buffer layers differ radically.

Kozyrev, S. P. [Russian Academy of Sciences, Lebedev Institute of Physics (Russian Federation)], E-mail: skozyrev@sci.lebedev.ru

2009-07-15T23:59:59.000Z

344

Profile NeutronDetector 9-16-04..pmd  

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

GALLIUM ARSENIDE SEMICONDUCTOR-BASED GALLIUM ARSENIDE SEMICONDUCTOR-BASED NEUTRON DETECTOR B E N E F I T S Portable, Accurate Device Detects and Monitors Neutrons and Nuclear Materials * More accurate and sensitive than other technologies * Performance won't degrade over time * Easy implementation and deployment * Rugged, lightweight, and portable for field use * Reduces false readings * Requires less power * Low mass-production cost (about $1 per chip) * Neutron detection * Detecting and monitoring nuclear materials and weapons * Permanent installations and portable field operation * High-vacuum environments (e.g., physics labs and space platforms) An advanced neutron detector developed by Argonne National Laboratory and Kansas State University accurately detects neutrons and finds concealed nuclear weapons and materials, even in harsh or challenging environments. The key

345

Development of electrochemical photovoltaic cells. Third technical progress report, November 1, 1979-January 31, 1980  

SciTech Connect (OSTI)

The development of stable, efficient, electrochemical photovoltaic cells based on silicon and gallium arsenide in non-aqueous electrolyte systems is being investigated. The effect of surface condition of silicon electrodes on electrochemical and physical characteristics has been studied. An electrode-supporting electrolyte interaction in acetonitrile has been identified which leads to etching of the surface. Improved performance can result, which has practical significance. Gallium arsenide electrodes have been electrochemically characterized in cells containing propylene carbonate with a ferrocene/ferricenium redox additive. Degradation of the ferricenium salt under illumination has been investigated. Other redox couples studied to date have not given promising results. Long-term stability experiments have been deferred while a better understanding of electrode behavior is being obtained.

Byker, H.J.; Schwerzel, R.E.; Wood, V.E.; Austin, A.E.; Brooman, E.W.

1980-03-07T23:59:59.000Z

346

Carrier localization in gallium nitride  

SciTech Connect (OSTI)

In wide bandgap GaN, a large number of interesting and important scientific questions remain to be answered. For example, the large free electron concentration reaching 10{sup 19} to 10{sup 20} cm{sup - 3} in nominally undoped material are ascribed to intrinsic defects because no chemical impurity has been found at such high concentrations. According to theoretical models, a nitrogen vacancy acts as a donor but its formation energy is very large in n-type materials, making this suggestion controversial. We have investigated the nature of this yet unidentified donor at large hydrostatic pressure. Results from infrared reflection and Raman scattering indicate strong evidence for localization of free carriers by large pressures. The carrier density is drastically decreased by two orders of magnitude between 20 and 30 GPa. Several techniques provide independent evidence for results in earlier reports and present the first quantitative analysis. A possible interpretation of this effect in terms of the resonant donor level is presented.

Wetzel, C. [Lawrence Berkeley National Lab., CA (United States)][California Univ., Berkeley, CA (United States); Walukiewicz, W. [Lawrence Berkeley National Lab., CA (United States); Haller, E.E. [Lawrence Berkeley National Lab., CA (United States)][California Univ., Berkeley, CA (United States)] [and others

1996-09-01T23:59:59.000Z

347

Compositional Mapping of Self-Assembled Monolayers Derivatized within Microfluidic Networks  

Science Journals Connector (OSTI)

Carboxylic acid terminated self-assembled monolayers (SAMs) deposited on epitaxial gold substrates were activated in situ using a water-soluble carbodiimide and N-hydroxysuccinimide reagents. ... 20,32 The master template was available in our laboratory having been previously manufactured by exposing and developing a photoresist pattern on a gallium arsenide wafer. ... Images were obtained in lateral force and pulsed force modes using Topometrix silicon nitride (Si3N4) tips in air. ...

Steven J. Hinder; Simon D. Connell; Martyn C. Davies; Clive J. Roberts; Saul J. B. Tendler; Philip M. Williams

2002-03-19T23:59:59.000Z

348

Hard and Soft X-ray Absorption Spectroscopic Investigation of Aqueous Fe(III)?Hydroxamate Siderophore Complexes  

Science Journals Connector (OSTI)

19 The atmospheric pressure was maintained inside the sample chamber by placing a 0.16 ?m silicon nitride window between the sample chamber and upstream ultrahigh vacuum environment. ... The absorption spectra were recorded by detecting sample fluorescence (F) using a gallium arsenide photodiode (Hamamatsu Corporation). ... In aqueous solutions, the solubility of Fe(III) is extremely low close to neutral pH and the Fe(III) concentration increases in acidic and alkaline solutions (Figure 2). ...

David C. Edwards; Satish C. B. Myneni

2005-10-21T23:59:59.000Z

349

Block Copolymer Templated Chemistry for the Formation of Metallic Nanoparticle Arrays on Semiconductor Surfaces  

Science Journals Connector (OSTI)

One of key ingredients for many future applications is the ability to precisely pattern nanoscale features on technologically relevant semiconductor surfaces such as silicon and germanium, as well as compound semiconductors such as gallium arsenide and indium phosphide. ... Deposition of these metals is possible presumably due to the water solubility of their oxides:? Ge oxide,14c As oxide,24 and P oxide25 are soluble in water. ...

Masato Aizawa; Jillian M. Buriak

2007-09-25T23:59:59.000Z

350

Growth of ?-Amyloid(1?40) Protofibrils by Monomer Elongation and Lateral Association. Characterization of Distinct Products by Light Scattering and Atomic Force Microscopy  

Science Journals Connector (OSTI)

Soluble intermediates in A? fibrillogenesis, termed protofibrils, have been identified previously, and here we describe the in vitro formation and isolation of A?(1?40) protofibrils by size exclusion chromatography. ... Hydrodynamic radius (RH) measurements were made at room temperature with a DynaPro MSX instrument (Protein Solutions Inc., Charlottesville, VA) containing a gallium aluminum arsenide laser. ... The solubility of A?(1?43) in water was substantially decreased by addition of buffered NaCl (60). ...

Michael R. Nichols; Melissa A. Moss; Dana Kim Reed; Wen-Lang Lin; Rajendrani Mukhopadhyay; Jan H. Hoh; Terrone L. Rosenberry

2002-04-17T23:59:59.000Z

351

Electronic parameters and interfacial properties of GaAs/AlxGa1-xAs multiquantum wells grown on (111)A GaAs by metalorganic vapor phase epitaxy  

Science Journals Connector (OSTI)

We report a comprehensive study of the optical and interfacial properties of GaAs/AlxGa1-xAs multiquantum wells grown on (111)A GaAs substrates by metalorganic vapor phase epitaxy which allowed the determination of the electronic parameters appropriate for such quantum wells. High-resolution x-ray diffractometry studies indicate an excellent crystal quality and good periodicity for the multiquantum wells and provided their structural parameters accurately. The photoreflectance spectra exhibit all the allowed and almost all the weakly allowed optical transitions between the confined hole and electron states. From an analysis of the photoreflectance spectra it is shown that the quantum well interfaces have an abruptness better than ±1 ML. Photoluminescence spectroscopy was also performed to evaluate independently the roughness of the interfaces and multiquantum well period reproducibility. For a 25-period multiquantum well structure with a well width of 55 Å, a photoluminescence linewidth of 12.5 meV, which corresponds to a combined well-width fluctuation and interface roughness of less than ±1 monolayer over the 25 periods, proves the achievement of heterointerfaces with excellent interfacial quality. From a detailed analysis of the high-order transitions observed in the photoreflectance spectra we determined key quantum well electronic parameters, such as, the heavy-hole valence-band offset Qv=0.33±0.02, the transverse GaAs heavy-hole effective mass mhh=(0.95±0.02)m0, and the light-hole effective mass mlh=0.08m0 in ?111? directions, for ?111?-oriented GaAs/AlxGa1-xAs quantum well structures.

Soohaeng Cho; A. Sanz-Hervás; A. Majerfeld; B. W. Kim

2003-07-10T23:59:59.000Z

352

Boron arsenide thin film solar cell development. Final report  

SciTech Connect (OSTI)

Pyrolytic decomposition of diborane and arsine has been used in attempts to grow polycrystalline BAs films. This method, however, produced only amorphous films for deposition temperatures below 920/sup 0/C and polycrystalline boron subarsenide (B/sub 12/As/sub 2/) flms for deposition temperatures above this value. The amorphous films have been determined to have a significant arsenic content but the actual stoichiometry was not obtained. The films were adherent on single crystal sapphire (0001), (111) silicon, (0001) SiC, and polycrystalline SiC but were found not to be adherent to substrates of fused quartz, tungsten, and molybdenum. It was also found that all films deposited above 650/sup 0/C were p-type while those deposited below 600/sup 0/C were usually n-type. Polycrystalline BAs and B/sub 12/As/sub 2/ was produced by reaction of the elements in a closed tube. The amorphous films showed an indirect or non-direct optical bandgap from 1.0 to 1.7 eV with the most probable values between 1.2 to 1.4 eV. The crystalline BAs powder shows a bandgap near 1.0 eV. Photoconductance time constants have been measured for films deposited on (0001) sapphire and (0001) SiC. Attempts at doping the amorphous films were generally unsuccessful. A polycrystalline powder sample was successfully doped with sulfur. Attempts were made to produce a Schottky barrier diode by evaporating Al dots onto an amorphous film on graphite without a post-evaporation anneal. An MIS structure was also attempted by baking an amorphous film in air at 280/sup 0/C before evaporation of aluminum. Although nonlinear characteristics were obtained, none of the devices showed any photovoltaic response. A p-type amorphous film was deposited on an n-type silicon substrate to form a p-n heterojunction. This device did exhibit a photovoltaic response but it is believed that the photogeneration was occurring primarily in the silicon substrate.

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

1980-09-01T23:59:59.000Z

353

Transport in the quantum critical regime of the iron arsenide...  

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

emerges, one whose thermodynamic and transport properties differ from the unified phenomenology with which we understand conventional metals - the Landau-Fermi liquid theory -...

354

Induced Optical Losses in Optoelectronic Devices due to Focused Ion Beam Damages  

E-Print Network [OSTI]

A study of damages caused by gallium focused ion beam (FIB) into III-V compounds is presented. Potential damages caused by local heating, ion implantation, and selective sputtering are presented. Preliminary analysis shows that local heating is negligible. Gallium implantation is shown to occur over areas tens of nanometers thick. Gallium accumulation as well as selective sputtering during III-V compounds milling is expected. Particularly, for GaAs, this effect leads to gallium segregation and formation of metallic clusters. Microdisk resonators were fabricated using FIB milling with different emission currents to analyze these effects on a device. It is shown that for higher emission current, thus higher implantation doses, the cavity quality factor rapidly decreases due to optical scattering losses induced by implanted gallium atoms.

Vallini, Felipe; Reis, Elohim Fonseca dos; von Zuben, Antônio Augusto; Frateschi, Newton Cesário

2012-01-01T23:59:59.000Z

355

Evaluation of matrix elements of the 8×8 k?p Hamiltonian with k-dependent spin-orbit contributions for the zinc-blende structure of GaAs  

Science Journals Connector (OSTI)

The k?p method of band-structure calculation provides a detailed description of a crystal’s energy dispersion near a high symmetry point in the first Brillouin zone. The resulting parameters of this calculation are a series of momentum matrix elements. Presented here is a set of band-structure parameters for the zinc-blende structure of GaAs at the ? point that takes the lack of inversion symmetry into account as well as k-dependent spin-orbit contributions to the Hamiltonian. A comprehensive optimization was performed in order to satisfy effective mass data as well as conduction band spin-splitting data. It was found that the lack of inversion symmetry has a profound influence on the nonparabolicity of the conduction band and the contribution of the k-dependent spin-orbit effect cannot be ignored in the calculation of the effective mass of the conduction, light hole, and spin-orbit bands. © 1996 The American Physical Society.

T. E. Ostromek

1996-11-15T23:59:59.000Z

356

Effect of spacer layer thickness on multi-stacked InGaAs quantum dots grown on GaAs (311)B substrate for application to intermediate band solar cells  

Science Journals Connector (OSTI)

We have investigated the properties of multi-stacked layers of self-organized In0.4Ga0.6As quantum dots(QDs) on GaAs (311)B grown by molecular beam epitaxy. We found that a high degree of in-plane ordering of QDs structure with a six-fold symmetry was maintained though the growth has been performed at a higher growth rate than the conventional conditions. The dependence of photoluminescence characteristics on spacer layer thickness showed an increasing degree of electronic coupling between the stacked QDs for thinner spacer layers. The external quantum efficiency for an InGaAs/GaAs quantum dotsolar cell (QDSC) with a thin spacer layer thickness increased in the longer wavelength range due to additive contribution from QD layers inserted in the intrinsic region. Furthermore a photocurrent production by 2-step photon absorption has been observed at room temperature for the InGaAs/GaAs QDSC with a spacer layer thickness of 15?nm.

Yasushi Shoji; Kohei Narahara; Hideharu Tanaka; Takashi Kita; Katsuhiro Akimoto; Yoshitaka Okada

2012-01-01T23:59:59.000Z

357

Impact of stress relaxation in GaAsSb cladding layers on quantum dot creation in InAs/GaAsSb structures grown on GaAs (001)  

SciTech Connect (OSTI)

We describe InAs quantum dot creation in InAs/GaAsSb barrier structures grown on GaAs (001) wafers by molecular beam epitaxy. The structures consist of 20-nm-thick GaAsSb barrier layers with Sb content of 8%, 13%, 15%, 16%, and 37% enclosing 2 monolayers of self-assembled InAs quantum dots. Transmission electron microscopy and X-ray diffraction results indicate the onset of relaxation of the GaAsSb layers at around 15% Sb content with intersected 60° dislocation semi-loops, and edge segments created within the volume of the epitaxial structures. 38% relaxation of initial elastic stress is seen for 37% Sb content, accompanied by the creation of a dense net of dislocations. The degradation of In surface migration by these dislocation trenches is so severe that quantum dot formation is completely suppressed. The results highlight the importance of understanding defect formation during stress relaxation for quantum dot structures particularly those with larger numbers of InAs quantum-dot layers, such as those proposed for realizing an intermediate band material.

Bremner, S. P. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney 2052 (Australia)] [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney 2052 (Australia); Ban, K.-Y.; Faleev, N. N.; Honsberg, C. B. [School of Electrical, Computer and Energy Engineering, Ira A. Fulton Schools of Engineering, Solar Power Lab, Arizona State University, Tempe, Arizona 85287 (United States)] [School of Electrical, Computer and Energy Engineering, Ira A. Fulton Schools of Engineering, Solar Power Lab, Arizona State University, Tempe, Arizona 85287 (United States); Smith, D. J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)] [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

2013-09-14T23:59:59.000Z

358

Effects of crossed electric and magnetic fields on the electronic and excitonic states in bulk GaAs and GaAs?Ga1?xAlxAs quantum wells  

Science Journals Connector (OSTI)

The variational procedure in the effective-mass and parabolic-band approximations is used in order to investigate the effects of crossed electric and in-plane magnetic fields on the electronic and exciton properties in semiconductor heterostructures. Calculations are performed for bulk GaAs and GaAs?Ga1?xAlxAs quantum wells, for applied magnetic fields parallel to the layers and electric fields in the growth direction, and it is shown that the combined effects on the heterostructure properties of the applied crossed electric and magnetic fields and the direct coupling between the center-of-mass and internal exciton motions may be dealt with via a simple parameter representing the spatial distance between the centers of the electron and hole magnetic parabolas. Exciton properties are analyzed by using a simple hydrogenlike envelope excitonic wave function and present theoretical results are found in fair agreement with available experimental measurements on the diamagnetic shift of the photoluminescence peak position of GaAs?Ga1?xAlxAs quantum wells under in-plane magnetic fields.

M. de Dios-Leyva, C. A. Duque, and L. E. Oliveira

2007-01-02T23:59:59.000Z

359

Superconductive silicon nanowires using gallium beam lithography.  

SciTech Connect (OSTI)

This work was an early career LDRD investigating the idea of using a focused ion beam (FIB) to implant Ga into silicon to create embedded nanowires and/or fully suspended nanowires. The embedded Ga nanowires demonstrated electrical resistivity of 5 m-cm, conductivity down to 4 K, and acts as an Ohmic silicon contact. The suspended nanowires achieved dimensions down to 20 nm x 30 nm x 10 m with large sensitivity to pressure. These structures then performed well as Pirani gauges. Sputtered niobium was also developed in this research for use as a superconductive coating on the nanowire. Oxidation characteristics of Nb were detailed and a technique to place the Nb under tensile stress resulted in the Nb resisting bulk atmospheric oxidation for up to years.

Henry, Michael David; Jarecki, Robert Leo,

2014-01-01T23:59:59.000Z

360

Electronic properties of gallium nitride nanowires  

E-Print Network [OSTI]

This thesis presents a systematic study of the electrical transport in GaN nanowires. Particularly, the effect of the surrounding dielectric on the conductivity of GaN nanowires is experimentally shown for the first time. ...

Yoon, Joonah

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Interactions of gallium with zircaloy cladding  

E-Print Network [OSTI]

CHAPTER I INTRODUCTION The accepted options for the disposition of weapons-grade plutonium (WGPu) are immobilization or conversion to a mixed-oxide (MOX) reactor fuel. There are two benefits of conversion, one, the plutonium can't be converted back... into a viable weapon and two, the material could be used as an energy producing natural resource. Typical reactors use uranium dioxide enriched with about 3'le U-235. The proposed MOX fuel would consist of depleted uranium with WGPu. In order...

Mitchell, Lee Josey

2012-06-07T23:59:59.000Z

362

Spectroscopy of gallium selenide nanoparticle nuclei  

E-Print Network [OSTI]

by the presence of GaSe nanoparticle nuclei which are non-Superradiance in GaSe Nanoparticle Aggregates”, Journal ofStrongly-Coupled GaSe Nanoparticle Aggregates”, Journal of

Lair, Deborah L.

2011-01-01T23:59:59.000Z

363

Multichannel, time-resolved picosecond laser ultrasound imaging and spectroscopy with custom complementary metal-oxide-semiconductor detector  

SciTech Connect (OSTI)

This paper presents a multichannel, time-resolved picosecond laser ultrasound system that uses a custom complementary metal-oxide-semiconductor linear array detector. This novel sensor allows parallel phase-sensitive detection of very low contrast modulated signals with performance in each channel comparable to that of a discrete photodiode and a lock-in amplifier. Application of the instrument is demonstrated by parallelizing spatial measurements to produce two-dimensional thickness maps on a layered sample, and spectroscopic parallelization is demonstrated by presenting the measured Brillouin oscillations from a gallium arsenide wafer. This paper demonstrates the significant advantages of our approach to pump probe systems, especially picosecond ultrasonics.

Smith, Richard J.; Light, Roger A.; Johnston, Nicholas S.; Pitter, Mark C.; Somekh, Mike G. [Institute of Biophysics, Imaging and Optical Science, University of Nottingham, Nottinghamshire NG7 2RD (United Kingdom); Sharples, Steve D. [Applied Optics Group, Electrical Systems and Optics Research Division, University of Nottingham, Nottinghamshire NG7 2RD (United Kingdom)

2010-02-15T23:59:59.000Z

364

Characterization of Irradiated Starches by Using FT-Raman and FTIR Spectroscopy  

Science Journals Connector (OSTI)

Degradation of starch polymers resulting in decreased viscosity and increased water solubility, and increased acidity with increasing radiation doses are potential changes observed in irradiated starches. ... FT-Raman spectra were obtained using a Nicolet 870 spectrometer with the Raman module 32B (Madison, WI) and Nd:YAG laser operating at 1064 nm with a maximum power of 2 W. The system was equipped with an InGaAs (Indium?Gallium Arsenide) detector, XT-KBr beam-splitter with 180° reflective optics, and a fully motorized sample position adjustment feature. ...

Ramazan Kizil; Joseph Irudayaraj; Koushik Seetharaman

2002-06-07T23:59:59.000Z

365

Crystal Engineering Approach To Forming Cocrystals of Amine Hydrochlorides with Organic Acids. Molecular Complexes of Fluoxetine Hydrochloride with Benzoic, Succinic, and Fumaric Acids  

Science Journals Connector (OSTI)

Raman spectroscopic analyses were carried out on a Thermo Nicolet 960 spectrometer equipped with an indium gallium arsenide (InGaAs) detector. ... Fluoxetine hydrochloride and cocrystals 2 and 4 were stable in water at 20 °C such that the equilibrium solubility values could be obtained at this temperature (Table 7). ... Approximate solubilities in water are as follows:? benzoic acid, 0.34 g/100 g at 25 °C;18 succinic acid, 7.5 g/100 g at 25 °C;19 fumaric acid, 0.61 g/100 g at 25 °C. ...

Scott L. Childs; Leonard J. Chyall; Jeanette T. Dunlap; Valeriya N. Smolenskaya; Barbara C. Stahly; G. Patrick Stahly

2004-09-24T23:59:59.000Z

366

Soluble, Infrared-Absorbing Croconate Dyes from 2,6-Di-tert-butyl-4-methylchalcogenopyrylium Salts  

Science Journals Connector (OSTI)

1 Although many squarylium dyes have limited solubility in organic solvents or in coated organic films, squarylium dyes 1 (Chart 1) derived from 2,6-di-tert-butyl-4-methylchalcogenopyrylium salts (2)3 are soluble and have been coated in organic thin films for a variety of applications. ... The croconates are readily prepared, are soluble in organic solvents, and have absorption maxima that cover a broad range of laser emission lines from gallium?arsenide diode lasers (?820 nm) to the neodinium-YAG laser (1064 nm). ... The reaction mixture was poured into water (50 mL), and the product was extracted with hexanes (3 × 25 mL). ...

Todd P. Simard; Jian H. Yu; Jennifer M. Zebrowski-Young; Neil F. Haley; Michael R. Detty

2000-03-03T23:59:59.000Z

367

Fouling and Corrosion Properties of SiO2 Coatings on Copper in Geothermal Water  

Science Journals Connector (OSTI)

The main goal of this work was to explore the antifouling and anticorrosion characteristics of LPD-prepared low-energy inorganic SiO2 coatings on copper substrates with nanometer-scale film thicknesses in low- and medium-temperature geothermal waters, as no open literature could be found in this area. ... SiO2 films on substrates of Si wafer, glass, gallium arsenide, and SiGe, among others, have been successfully obtained with the LPD method. ... Stathoulopoulou, A.; Demadis, K. D.Enhancement of silicate solubility by use of “green” additives: Linking green chemistry and chemical water treatment Desalination 2008, 224, 223 ...

Chen Ning; Liu Mingyan; Zhou Weidong

2012-04-02T23:59:59.000Z

368

Synthesis of Metallic Nanostructures Using Chemical Fluid Deposition  

Science Journals Connector (OSTI)

Department of Chemical Engineering, and Department of Physics and Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China ... A solubility study of the platinum precursor, platinum(II) dimethylcyclooctadiene, in the supercritical carbon dioxide was carried out to obtain a phase diagram in order to optimize the operating parameters required for the metal deposition process. ... Korgel and Hanrath and co-workers had also published work on synthesizing nanowires of semiconducting materials, such as silicon, germanium, and gallium arsenide(22-25) using gold seeding particles. ...

Candy S. Lin; Frank Leung-Yuk Lam; Xijun Hu; Wing Yim Tam; Ka M. Ng

2008-06-18T23:59:59.000Z

369

NREL: News - NREL Reports 31.1% Efficiency for III-V Solar Cell  

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

913 913 NREL Reports 31.1% Efficiency for III-V Solar Cell Conversion-efficiency mark is a world record for a two-junction solar cell measured under one-sun illumination June 24, 2013 The Energy Department's National Renewable Energy Lab has announced a world record of 31.1% conversion efficiency for a two-junction solar cell under one sun of illumination. NREL Scientist Myles Steiner announced the new record June 19 at the 39th IEEE Photovoltaic Specialists Conference in Tampa, Fla. The previous record of 30.8% efficiency was held by Alta Devices. The tandem cell was made of a gallium indium phosphide cell atop a gallium arsenide cell, has an area of about 0.25 square centimeters and was measured under the AM1.5 global spectrum at 1,000 W/m2. It was grown inverted, similar to the NREL-developed inverted metamorphic multi-junction

370

Bates GaAs polarized electron source  

SciTech Connect (OSTI)

In order to pursue measurements of parity violating effects of the neutral weak current, we have developed a polarized electron source suitable for installation at the MIT-Bates Linear Accelerator. The source is designed to provide a high peak-current pulsed beam that has a approx. 1% duty factor and that is extremely stable under helicity reversal. 34 references, 6 figures, 1 table.

Schaefer, H.R.; Cates, G.; Michaels, R.; Hughes, V.W.. Lubell, M.S.; Souder, P.A.

1983-05-01T23:59:59.000Z

371

Synthesis and Characterization of Bulk Vitreous Cadmium Germanium...  

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

Bulk Vitreous Cadmium Germanium Arsenide. Synthesis and Characterization of Bulk Vitreous Cadmium Germanium Arsenide. Abstract: Abstract Cadmium-germanium-diarsenide...

372

Solvothermal synthesis and characterisation of new one-dimensional indium and gallium sulphides: [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[InS{sub 2}] and [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[GaS{sub 2}  

SciTech Connect (OSTI)

Two new main group metal sulphides, [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[InS{sub 2}] (1) and [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[GaS{sub 2}] (2) have been prepared solvothermally in the presence of 1,4-bis(3-aminopropyl)piperazine and their crystal structures determined by single-crystal X-ray diffraction. Both compounds are isostructural and crystallise in the monoclinic space group P2{sub 1}/n (Z=4), with a=6.5628(5), b=11.2008(9), c=12.6611(9) A and {beta}=94.410(4){sup o} (wR=0.035) for compound (1) and a=6.1094(5), b=11.2469(9), c=12.7064(10) A and {beta}=94.313(4){sup o} (wR=0.021) for compound (2). The structure of [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[MS{sub 2}] (M=In,Ga) consists of one-dimensional [MS{sub 2}]{sup -} chains which run parallel to the crystallographic a axis and are separated by diprotonated amine molecules. These materials represent the first example of solvothermally prepared one-dimensional gallium and indium sulphides. -- Graphical abstract: [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[InS{sub 2}] and [C{sub 1}N{sub 4}H{sub 26}]{sub 0.5}[GaS{sub 2}], prepared under solvothermal conditions, consist of one-dimensional [MS{sub 2}]{sup -} chains separated by diprotonated 1,4-bis(3-aminopropyl)piperazine molecules.

Vaqueiro, Paz [Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)]. E-mail: chepv@hw.ac.uk

2006-01-15T23:59:59.000Z

373

Development of indium arsenide quantum dot solar cells for high conversion efficiency.  

E-Print Network [OSTI]

??Sunlight is the largest energy source available on earth. Under clear conditions there is approximately 1,000 watts per directly incident square meter, which reaches the… (more)

El-Emawy, Mohamed

2009-01-01T23:59:59.000Z

374

E-Print Network 3.0 - arsenide x-ray imaging Sample Search Results  

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

Electrons suffer from significant... collimated beams of X-rays (usually from a synchroton or storage ring). This has the advantage of producing... , proton-beam writing...

375

Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides  

E-Print Network [OSTI]

5.11: Zero ?eld electrical resistivity vs temperature ?(T )technique. The electrical resistivity ? vs temperature T5.3: The zero-?eld electrical resistivity ? vs temperature T

Sayles, Todd Allen

2008-01-01T23:59:59.000Z

376

PROCESSING ISSUES IN THE DEVELOPMENT OF INDIUM-ARSENIDE-BASE HETEROJUNCTION BIPOLAR TRANSISTORS  

E-Print Network [OSTI]

, the forward plasma power was kept at $100 W with 5.0 sccm CF4 plus 10.0 sccm Ar gas flow. The dry etching rate

377

E-Print Network 3.0 - arsenide integrated circuit Sample Search...  

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

-3:40pm Summary: 02139 A novel epitaxy-on-electronics process for fabricating optoelectronic integrated circuits (OE- ICs... integrated circuit technology base, this...

378

E-Print Network 3.0 - arsenide p-i-n detectors Sample Search...  

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

Sciences ; Engineering 52 header for SPIE use Integrated cooling for optoelectronic devices Summary: from similar materials. Experimental analysis of an InP p-i-n diode...

379

E-Print Network 3.0 - arsenide inas quantum Sample Search Results  

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

Nanometer-scale islands that form spontaneously on a semiconductor... and optoelectronic devices, quantum computing, and History, information storage. Highlights, ... Source:...

380

E-Print Network 3.0 - arsenide junction-field-effect transistors...  

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

Texas at Arlington Materials Science and Engineering Department Summary: and optoelectronic devices. Topics include electrical properties of semiconductors, p-n junctions,...

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides  

E-Print Network [OSTI]

in the conduction band The Josephson junction . . . . . .1.4: A diagram of a Josephson junction, consisting of tworings joined by two Josephson junctions. The current through

Sayles, Todd Allen

2008-01-01T23:59:59.000Z

382

Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides  

E-Print Network [OSTI]

1.3 Magnetism . . . . .1.3.3 Itinerant Magnetism . . . . . . . . . . .3.3 Magnetism . . . . . . . . . . . . . . . . . . . . . 3.4

Sayles, Todd Allen

2008-01-01T23:59:59.000Z

383

E-Print Network 3.0 - arsenide photoconductive detectors Sample...  

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

7 Terahertz emission from black silicon M. Theuer,2 Summary: -called photoconductive terahertz emitters and detectors, radiation-damaged silicon on sapphire or low-...

384

E-Print Network 3.0 - arsenide single crystals Sample Search...  

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

Technion, Israel Institute of Technology Collection: Engineering ; Materials Science 73 Tunable narrow-bandwidth source of THz radiation based on frequency down-conversion in...

385

Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides  

E-Print Network [OSTI]

H. J. Kang, J. W. Lynn, Pengcheng Dai, S. K. McCall, M. W.H. J. Kang, J. W. Lynn, Pengcheng Dai, S. K. McCall, M. W.H. J. Kang, J. W. Lynn, Pengcheng Dai, S. K. McCall, M. W.

Sayles, Todd Allen

2008-01-01T23:59:59.000Z

386

Neutron irradiation effects on gallium nitride-based Schottky diodes  

SciTech Connect (OSTI)

Depth-resolved cathodoluminescence spectroscopy (DRCLS), time-resolved surface photovoltage spectroscopy, X-ray photoemission spectroscopy (XPS), and current-voltage measurements together show that fast versus thermal neutrons differ strongly in their electronic and morphological effects on metal-GaN Schottky diodes. Fast and thermal neutrons introduce GaN displacement damage and native point defects, while thermal neutrons also drive metallurgical reactions at metal/GaN interfaces. Defect densities exhibit a threshold neutron fluence below which thermal neutrons preferentially heal versus create new native point defects. Scanning XPS and DRCLS reveal strong fluence- and metal-dependent electronic and chemical changes near the free surface and metal interfaces that impact diode properties.

Lin, Chung-Han; Katz, Evan J.; Zhang, Zhichun [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States)] [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States); Qiu, Jie; Cao, Lei [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)] [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Mishra, Umesh K. [Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of California, Santa Barbara, California 93106 (United States)] [Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of California, Santa Barbara, California 93106 (United States); Brillson, Leonard J. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States) [Department of Electrical and Computer Engineering, The Ohio State University, Columbus Ohio 43210 (United States); Department of Physics and Center for Materials Research, The Ohio State University, Columbus, Ohio 43210 (United States)

2013-10-14T23:59:59.000Z

387

Au-free Ohmic Contacts to Gallium Nitride and Graphene  

E-Print Network [OSTI]

. ................................................................................................. 43 Figure 28 Specific contact resistivity of co-sputtered Ti-Ta contact calculated after RTA at different temperatures ......................................................... 43 Figure 29 PMMA transfer method for transferring CVD grown...

Ravikirthi, Pradhyumna

2014-08-10T23:59:59.000Z

388

Production of gallium-66, positron emitting nuclide for radioimmumotherapy  

SciTech Connect (OSTI)

Excitation functions for production of {sup 66}Ga via {alpha}-induced nuclear reactions on enriched {sup 66}Zn have been measured with E{sub {alpha}}{le}27.3 MeV and E{sub {alpha}}{le}43.7 MeV employing the stack-thin target technique. In addition, the induced activity of {sup 67}Ga in the same sets of targets allowed an evaluation of the excitation functions of the corresponding nuclear reactions. 17 refs., 2 figs., 2 tabs.

Mirzadeh, S. (Oak Ridge National Lab., TN (USA)); Chu, Yung Yee (Brookhaven National Lab., Upton, NY (USA))

1991-01-01T23:59:59.000Z

389

Sandia National Laboratories: copper-indium-gallium-[di]selenide...  

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

Regional Testing Center (PV RTC), Renewable Energy, Solar, Solar Newsletter, SunShot HelioVolt, Sandia National Laboratories, the National Renewable Energy Laboratory,...

390

High-Quality, Low-Cost Bulk Gallium Nitride Substrates  

Broader source: Energy.gov [DOE]

To develop ESG into a viable bulk growth process for GaN that is more scalable to large-area wafer manufacturing and able to produce cost-effective, high-quality bulk GaN substrates.

391

Superconductivity in gallium-substituted Ba8Si46 clathrates  

E-Print Network [OSTI]

superconductor, with an onset at T-C approximate to 3.3 K. For x=10 and higher, no superconductivity was observed down to T=1.8 K. This represents a strong suppression of superconductivity with increasing Ga content, compared to Ba8Si46 with T-C approximate to 8...

Li, Yang; Zhang, Ruihong; Liu, Yang; Chen, Ning; Luo, Z. P.; Ma, Xingqiao; Cao, Guohui; Feng, Z. S.; Hu, Chia-Ren; Ross, Joseph H., Jr.

2007-01-01T23:59:59.000Z

392

Rutherford backscattering analysis of gallium implanted 316 stainless steel  

E-Print Network [OSTI]

Experimental Procedure Sample Analysis 3 3 . 9 . 11 HI THEORY. . IH. 1 Backscattering Principles HI. 2 The RBS Spectrum IH. 3 The Surface Energy Approximation . . . HI. 4 Stainless Steel 316. . IV RESULTS AND DISCUSSION . . 13 . 13 15... for the disposition of weapons grade (WG) plutonium (Pu) in the United States: MOX fuel conversion and immobilization. The first option uses nuclear reactors to transmutate WG Pu and the second imbeds the WG Pu in glass logs for deep burial. Due to the large amount...

Ortensi, Javier

2012-06-07T23:59:59.000Z

393

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

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

5µm layer experienced tensile strain. Dynamic Secondary Ion Mass Spectrometry (SIMS) depth profiles show that the 15µm template layer device had an average indium...

394

TVDG LET Calculator  

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

To The B N L Tandem Van de Graaff Accelerator To The B N L Tandem Van de Graaff Accelerator TVDG LET Calculator This program calculates the Peak LET, Corresponding Energy and Range as well as the LET and Range at the Specified Energy for the Specified Ion in the Specified Target. Select the Target Material from the dropdown list. Select the Ion Specie from the dropdown list. Enter the Total Ion Energy in the text box. This is equal to the Atomic Mass times the Energy/Nucleon. Click the 'Calculate' button or press the 'Enter' key. The Peak LET, Corresponding Energy and Range as well as the LET and Range at the Specified Energy for the Specified Ion in the Specified Target will be returned. Select your Target from the list Air Aluminum Oxide Carbon Copper Gallium Arsenide Gold Polyester Polyethylene Silicon Silicon Dioxide Skin Soda Lime Glass Sodium Iodide Water Select your Ion from the list

395

Definition: Semiconductor | Open Energy Information  

Open Energy Info (EERE)

Semiconductor Semiconductor Jump to: navigation, search Dictionary.png Semiconductor Any material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.[1] View on Wikipedia Wikipedia Definition A semiconductor is a material which has electrical conductivity to a degree between that of a metal (such as copper) and that of an insulator (such as glass). Semiconductors are the foundation of modern solid state electronics, including transistors, solar cells, light-emitting diodes (LEDs), quantum dots and digital and analog integrated circuits. A semiconductor may have a number of unique properties, one of which is the

396

COBRA: Determining Atomic Positions in Thin-Film Structures and Interfaces  

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

COBRA: Determining Atomic Positions in Thin-Film Structures and Interfaces COBRA: Determining Atomic Positions in Thin-Film Structures and Interfaces Coherent Bragg rod analyses (COBRA) experiments using synchrotron x-rays at Argonne's Advanced Photon Source (MHATT-CAT and PNC-CAT beamlines) directly revealed the sub-angstrom atomic interaction of epitaxial films with substrates. Information on how atoms in the adjoining layers of the film and substrate rearrange to mimic each other may lead to improvements in semiconductor manufacturing and the development of novel heterostructure materials, such as multilayer ferroelectrics, magnetic nanostructures and thin film superconductors. COBRA electron density map of a Gd2O3 film on a gallium arsenide substrate. The peaks correspond to folded Gd atomic positions parallel to the plane of the substrate.

397

CX-005363: Categorical Exclusion Determination | Department of Energy  

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

5363: Categorical Exclusion Determination 5363: Categorical Exclusion Determination CX-005363: Categorical Exclusion Determination Solar Junction's 100 Megawatt Manufacturing Line CX(s) Applied: B1.31 Date: 03/04/2011 Location(s): San Jose, California Office(s): Loan Guarantee Program Office The Department of Energy's proposed action is to issue a loan guarantee to Solar Junction to finance a 100 megawatt (MW) solar cell manufacturing line for multifunction photovoltaic solar cells to expand their existing 7 MW Demonstration Facility at 401 Charcot Avenue, San Jose, California 95131. The proposed project will commercialize an entirely new class of high-efficiency solar cells and concentrating photovoltaic components that incorporate high performance junctions formed with a tunable band gap semiconductor material, Gallium Indium Nitride Arsenide.

398

NREL photovoltaic subcontract reports: Abstracts and document control information, 1 August 1991--31 July 1992  

SciTech Connect (OSTI)

This report contains document control information and abstracts for the National Renewable Energy Laboratory (NREL) subcontracted photovoltaic program publications. It also lists source information on additional publications that describe US Department of Energy (DOE) PV research activities. It is not totally exhaustive, so it lists NREL contacts for requesting further information on the DOE and NREL PV programs. This report covers the period from August 1, 1991, through July 31, 1992. The purpose of continuing this type of publication is to help people keep abreast of specific PV interests, while maintaining a balance on the costs to the PV program. The information in this report is organized under PV technology areas: Amorphous silicon research; polycrystalline thin films (including copper indium diselenide, cadmium telluride, and thin-film silicon); crystalline materials and advanced concepts (including silicon, gallium arsenide, and other group III-V materials); and PV manufacturing technology development (which may include manufacturing information for various types of PV materials).

Not Available

1992-08-01T23:59:59.000Z

399

Crystal Structure and Spectroscopic Characterization of a Luminescent Europium Chelate  

Science Journals Connector (OSTI)

This ligation removes the last water bound to the primary coordination sphere of europium, resulting in no waters bound to the lanthanide. ... 6,11-13 Their utility arises because of the lanthanide's unusual spectroscopic emission characteristics, which include millisecond lifetime, spiked emission peaks (150 nm), potentially high quantum yields (?1), and excellent solubility. ... A pulsed nitrogen laser (337 nm, 5 ns pulse-width, 40 Hz repetition rate; Laser Photonics) excited the Eu-DTPA-cs124 sample, and emission was passed through a double-monochromator (SPEX 1680B, blaze = 500 nm, f/4) and detected by a gallium arsenide photomultiplier tube operating in photon-counting mode (Hamamatsu R943-02) with associated electronics (MITEQ 500 MHz preamplifier; Ortec 854 gated discriminator; Canberra FMS multichannel scalar with 2 ?s time resolution). ...

Paul R. Selvin; Jaru Jancarik; Min Li; Li-Wei Hung

1996-01-31T23:59:59.000Z

400

Poly(arylene ether sulfone) Statistical Copolymers Bearing Perfluoroalkylsulfonic Acid Moieties  

Science Journals Connector (OSTI)

Number-average molecular weight (Mn) and polydispersity index (PDI) of the polymeric materials were measured using a gel permeation chromatography (GPC) system consisting of a Waters Alliance 2695 separation module, an online multiangle laser light scattering (MALLS) detector fitted with a gallium arsenide laser (power: 20 mW) operating at 690 nm (MiniDAWN, Wyatt Technology Inc.), an interferometric refractometer (Optilab DSP, Wyatt Technology Inc.), and two Polymer Laboratories mixed D columns (5 ?m bead size) connected in series. ... (23) After experimentation with several alternative neutralizing agents including pyridine and alkali metal hydroxides and carbonates, we determined that the aliphatic tertiary amine, N,N-diisopropylethylamine, produces a salt with favorable solubility and crystallization behavior. ... It is sparingly soluble in water, which facilitates isolation, and as will be shown, it may be used directly in polymerization, and under these conditions, the free amine is released and volatilized out of the polymer product. ...

Haibo Li; Andrew B. Jackson; Nathan J. Kirk; Kenneth A. Mauritz; Robson F. Storey

2011-01-19T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Interference Prevention in Size-Exclusion Chromatographic Analysis of Debranched Starch Glucans by Aqueous System  

Science Journals Connector (OSTI)

The barium acetate reacts with ammonium sulfate and produces barium sulfate, the latter having very low solubility (0.00115 g/L at 18 °C) and can be easily removed by filtration (Figure 9). ... In some cases, a weak anionic water-soluble polymer, dextran (Mw = 2 kg/mol), could be excluded from the pores of silica gel upon elution with water,(39) but a mixture of pullulans was eluted without a good correlation with molecular size when a silica gel packed column was eluted with water (data not show). ... (43, 44) In the present system, the laser detector with a vertically polarized 30 mW gallium-arsenide laser operating at ? = 690 nm gave less noise upon the elution with sodium nitrate (Figure 5). ...

Amy Hui-Mei Lin; Yung-Ho Chang; Wen-Bin Chou; Ting-Jang Lu

2011-05-09T23:59:59.000Z

402

Regenerative mode photo electrochemical cells in molten salt electrolytes. 1st four monthly report (1/31/80)  

SciTech Connect (OSTI)

The most promising photoelectrodes selected for use in the butyl pyridinium chloride-aluminum chloride room temperature molten salt are n-type silicon, gallium arsenide and cadmium telluride. The solubilities of these semiconductors are low, and their conduction and valence band edges are favorably located. Cadmium selenide and sulfide showed significant solubility in the melt, and the conduction band edge for p-type cadmium telluride was too close to the aluminum deposition potential. Several reversible redox couples have been identified, which could potentially be used in a photoelectrochemical cell. These include W/sup 5 +//W/sup 6 +/ and Eu/sup 2 +//Eu/sup 3 +/ as well as ferrocene and its derivatives.

Not Available

1980-01-01T23:59:59.000Z

403

Novel Porphyrin-Incorporated Hydrogels for Photoactive Intraocular Lens Biomaterials  

Science Journals Connector (OSTI)

It is possible that the resulting high concentration of TPPS may have cross-linked the hydrogels to such an extent that it significantly reduced the solubility and/or diffusion rate of oxygen into the doped polymers. ... The 1O2 detection system was a liquid-nitrogen-cooled Indium Gallium Arsenide (InGaAs) detector (Judson Technologies Inc., Montgomeryville, PA, type J22D-M204-R01M-60-1.7) with a 1 mm2 active area. ... Overall, the data for TMPyP in MAA:HEMA suggest that loading water-soluble porphyrins into swellable acrylate-based gels leads to only minor perturbation in the photophysical and 1O2 generating properties of their excited states. ...

Clare Brady; Steven E. J. Bell; Carole Parsons; Sean P. Gorman; David S. Jones; Colin P. McCoy

2007-01-03T23:59:59.000Z

404

Bent crystal selection and assembling for the LAUE project  

E-Print Network [OSTI]

For the first time, with the Laue project, bent crystals are being used for focusing photons in the 80-300 keV energy range. The advantage is their high reflectivity and better Point Spread Function with respect to the mosaic flat crystals. Simulations have already shown their excellent focusing capability which makes them the best candidates for a Laue lens whose sensitivity is also driven by the size of the focused spot. Selected crystals are Germanium (perfect, (111)) and Gallium Arsenide (mosaic, (220)) with 40 m curvature radius to get a spherical lens with 20 m long focal length. A lens petal is being built. We report the measurement technique by which we are able to estimate the exact curvature of each tile within a few percent of uncertainty and their diffraction efficiency. We also discuss some results.

Liccardo, Vincenzo; Frontera, Filippo; Valsan, Vineeth; Guidi, Vincenzo; Buffagni, Elisa

2013-01-01T23:59:59.000Z

405

The Story of a Cutting-Edge Solar Startup | Department of Energy  

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

The Story of a Cutting-Edge Solar Startup The Story of a Cutting-Edge Solar Startup The Story of a Cutting-Edge Solar Startup June 20, 2012 - 9:40am Addthis Erin R. Pierce Erin R. Pierce Digital Communications Specialist, Office of Public Affairs What does this project do? Watch the video to learn how Alta Devices manufacturers high performance solar cells at a low cost. Alta Devices is rethinking how high performance solar cells are made. The Silicon Valley startup has taken gallium arsenide -- an expensive semiconductor material that is incredibly efficient at turning sunlight into electricity -- and developed a commercially viable processes for manufacturing it into solar modules. In 2009, Alta Devices was selected to participate in the Energy Department's SunShot Incubator program. Now in its sixth iteration,

406

Liquid phase epitaxial growth of GaAs  

SciTech Connect (OSTI)

Research into new semiconductor materials for measurement of electromagnetic radiation over a wide range of energies has been an active field for several decades. There is a strong desire to identify and develop new materials which can lead to improved detectors. Such devices are expected to solve problems that cannot be solved using the semiconductor materials and device structures which have been traditionally used for radiation detection. In order for a detector which is subjected to some type of irradiation to respond, the radiation must undergo an interaction with the detector. The net result of the radiation interaction in a broad category of detectors is the generation of mobile electric charge carriers (electrons and/or holes) within the detector active volume. This charge is collected at the detector contacts and it forms the basic electrical signal. Typically, the collection of the charge is accomplished through the imposition of an electric field within the detector which causes the positive and/or negative charges created by the radiation to flow in opposite directions to the contacts. For the material to serve as a good radiation detector, a large fraction (preferably 100%) of all carriers created by the interacting incident radiation must be collected. Charge trapping by deep level impurities and structural defects can seriously degrade detector performance. The focus of this thesis is on far infrared and X-ray detection. In X-ray detector applications of p-I-n diodes, the object is to measure accurately the energy distribution of the incident radiation quanta. One important property of such detectors is their ability to measure the energy of individual incident photons with high energy resolution.

Wynne, D.I. [Univ. of California, Berkeley, CA (United States). Materials Science and Mineral Engineering; [Lawrence Berkeley National Lab., CA (United States)

1997-10-01T23:59:59.000Z

407

Weathering of cobalt arsenides: Natural assemblages and calculated stability relations among secondary Ca-Mg-Co arsenates and carbonates  

Science Journals Connector (OSTI)

...Sainfeldite Ca5(AsO3OH)2(AsO4)24 H2O Talmessite Ca2Mg(AsO4)22 H2O Vladimirite Ca5...hornesite [3] M, J Picropharmacolite + talmessite [4], [7] M, R Picropharmacolite...significant amounts of Co compared to talmessite. Paragenetic relationships The observed...

Gregor Markl; Michael A.W. Marks; Insa Derrey; Jan-Erik Gühring

408

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1996. Two companies in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LED's), laser diodes, photodetectors, and solar in research and development, specialty alloys, and other applications. Optoelectronic devices were used

409

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2006. One company in Utah  

E-Print Network [OSTI]

circuits. Optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes, photodetectors, specialty alloys, and other applications. Optoelectronic devices were used in areas such as aerospace

410

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1998. Two companies in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LED's), laser diodes, photodetectors, and solar and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

411

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2000. Two companies in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LED's), laser diodes, photodetectors, and solar and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

412

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2003. One company in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes, photodetectors, and solar cells, specialty alloys, and other applications. Optoelectronic devices were used in areas such as aerospace

413

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2012. One company in Utah  

E-Print Network [OSTI]

consumed was used in integrated circuits (ICs). Optoelectronic devices, which include laser diodes, light. Optoelectronic devices were used in areas such as aerospace, consumer goods, industrial equipment, medical

414

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2008. One company in Utah  

E-Print Network [OSTI]

circuits (ICs). Optoelectronic devices, which include laser diodes, light-emitting diodes (LEDs and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

415

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2001. Two companies in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes, photodetectors, and solar cells, specialty alloys, and other applications. Optoelectronic devices were used in areas such as consumer goods

416

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2005. One company in Utah  

E-Print Network [OSTI]

circuits. Optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes, photodetectors, specialty alloys, and other applications. Optoelectronic devices were used in areas such as aerospace

417

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2007. One company in Utah  

E-Print Network [OSTI]

circuits (ICs). Optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

418

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2009. One company in Utah  

E-Print Network [OSTI]

circuits (ICs). Optoelectronic devices, which include laser diodes, light-emitting diodes (LEDs and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

419

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2010. One company in Utah  

E-Print Network [OSTI]

circuits (ICs). Optoelectronic devices, which include laser diodes, light-emitting diodes (LEDs and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

420

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1999. Two companies in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LED's), laser diodes, photodetectors, and solar and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2011. One company in Utah  

E-Print Network [OSTI]

consumed was used in integrated circuits (ICs). Optoelectronic devices, which include laser diodes, light% was used in research and development, specialty alloys, and other applications. Optoelectronic devices were

422

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1997. Two companies in  

E-Print Network [OSTI]

in optoelectronic devices, which include light-emitting diodes (LED's), laser diodes, photodetectors, and solar and development, specialty alloys, and other applications. Optoelectronic devices were used in areas

423

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2004. One company in Utah  

E-Print Network [OSTI]

consumed was used in optoelectronic devices, which include light-emitting diodes (LEDs), laser diodes% was used in research and development, specialty alloys, and other applications. Optoelectronic devices were

424

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

E-Print Network [OSTI]

74 (19) 2821 (1999). F. H. Spedding, Rare-earth Elements, inby the use of rare- earth elements as color emitters inpowders activated with rare-earth elements Eu 3+ , Tb 3+ ,

Tao, Jonathan Huai-Tse

2010-01-01T23:59:59.000Z

425

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

E-Print Network [OSTI]

residential lighting using incandescent lights [2], as shownenergy used for the incandescent lamp is wasted as infraredlight source to replace incandescent lighting [1]. Figure

Tao, Jonathan Huai-Tse

2010-01-01T23:59:59.000Z

426

Pressure dependence of deep levels of the As antisite, the Ga-vacancy–As-interstitial pair, and of the stable and metastable states of EL2  

Science Journals Connector (OSTI)

We report density-functional theory calculations of the tetrahedral, isolated arsenic antisite (AsGa) in GaAs and of its metastable structure, gallium-vacancy–arsenic-interstitial pair (VGaAsi). In order to determine the pressure dependence of the defect levels, the self-consistent Green-function method is applied. The calculated results are in agreement with experimental data on the stable and metastable states of EL2. This implies that the stable state of EL2 is indeed well described by the properties of the isolated As antisite. Furthermore, the results support the identification of the metastable state of EL2 with the VGaAsi pair and identify the symmetry of the pressure-induced defect level.

Christine Ziegler; Udo Scherz; Matthias Scheffler

1993-06-15T23:59:59.000Z

427

Gallium Safety in the Laboratory INEEL/CON-03-00078  

Office of Scientific and Technical Information (OSTI)

This is a preprint of a paper intended for publication in a This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are

428

Dependence of carrier mobility on an electric field in gallium selenide crystals  

SciTech Connect (OSTI)

The dependence of the mobility of charge carriers on voltage has been studied in undoped GaSe single crystals and crystals doped with gadolinium; the latter crystals have exhibited various values of dark resistivity ({rho}{sub d.r} Almost-Equal-To 10{sup 4}-10{sup 8} {Omega} cm at 77 K) and of the doping level (N = 10{sup -5}, 10{sup -4}, 10{sup -3}, 10{sup -2}, and 10{sup -1} at %). It is established that the dependence of the charge-carrier mobility on the electric field applied to the sample E {<=} 10{sup 2} V/cm is observed in undoped high-resistivity GaSe crystals ({rho}{sub d.r} {>=} 10{sup 4} {Omega} cm) and in lightly doped GaSe crystals (N {<=} 10{sup -2} at %) in the region of T {<=} 150 K. It is found that this dependence is not related to heating of the charge carriers by an electric field; rather, it is caused by elimination of drift barriers as a result of injection.

Abdinov, A. Sh., E-mail: abdinov_axmed@yahoo.com; Babaeva, R. F., E-mail: Babaeva-Rena@yandex.ru; Rzayev, R. M. [Baku State University (Azerbaijan)

2012-06-15T23:59:59.000Z

429

Structure and electronic properties of saturated and unsaturated gallium nitride nanotubes  

SciTech Connect (OSTI)

The atomic and electronic structures of saturated and unsaturated GaN nanotubes along the [001] direction with (100) lateral facets are studied using first-principles calculations. Atomic relaxation of nanotubes shows that appreciable distortion occurs in the unsaturated nanotubes. All the nanotubes considered, including saturated and unsaturated ones, exhibit semiconducting, with a direct band gap. Surface states arisen from the threefold-coordinated N and Ga atoms at the lateral facets exist inside the bulk-like band gap. When the nanotubes saturated with hydrogen, these dangling bond bands are removed from the band gap, but the band gap decreases with increasing the wall thickness of the nanotubes.

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

2009-11-05T23:59:59.000Z

430

Growth Kinetics and Doping of Gallium Nitride Grown by rf-Plasma Assisted Molecular Beam Epitaxy  

E-Print Network [OSTI]

Thomas H. Myers, Ph.D., Chair Larry E. Halliburton, Ph.D. Nancy C. Giles, Ph.D. Charter D. Stinespring Giles, Dr. Charter Stinespring, Dr. Larry Halliburton, and Dr. Mohindar Seehra. In addition, I would

Myers, Tom

431

Theoretical study of sequential oxidation of clusters of gallium oxide: Ga3On (n: 48)  

E-Print Network [OSTI]

as well as addition (and removal) of an electron leads to significant changes in the geometry oxide clusters, we found that the structural changes induced by addition and removal of an electron properties of neutral and ionized small GamOn (m,n = 1,2) clusters [2]. Addition of an electron introduced

Pandey, Ravi

432

The determination of titanium, germanium and gallium by charged particle activation analysis  

E-Print Network [OSTI]

V FWHM for the 1. 332 MeV y-ray of Co; Peak-to-Compton ratio: 20. 1; 60 Efficiency relative to a 3 x 3 inch NaI (Tl) detector for the 1. 332 MeV y-ray measured at 25 cm distance: 3 05%%d Data Ac uisition and Processin Data was acquired via a 4096... of the reaction had to be sufficiently high to make measurements of ppm level concentrations feasible. The thick target yields were calculated by correlating the activities of the particular Y-rays 16 back to the time at the end of the irradiation...

Novak, Leo Robert

1975-01-01T23:59:59.000Z

433

Luminescent Properties of CdS Crystals Doped with Gallium and Tellurium in Cadmium Vapor  

Science Journals Connector (OSTI)

A technique is devised for vapor-phase doping CdS in the quaternary system Cd–Ga–Te–S. CdS crystals are doped with Ga and Te via four-zone ... and Cd (the more volatile component of CdS). The luminescence spectra...

I. N. Odin; M. V. Chukichev; M. E. Rubina

2003-07-01T23:59:59.000Z

434

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

435

4.2.3.4 Magnetic neutron scattering in terbium, holmium and dysprosium gallium garnets  

Science Journals Connector (OSTI)

This document is part of Subvolume E ‘Garnets’ of Volume 27 ‘Magnetic Properties of Non-Metallic Inorganic Compounds Based on Transition Elements’ of Landolt-Börnstein - Group III Condensed Matter.

Z. A. Kazei; N. P. Kolmakova; V. I. Sokolov

1991-01-01T23:59:59.000Z

436

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

Science Journals Connector (OSTI)

...lighting research and development: Multi-year program plan) ( US DoE , Washington, DC ) Available from http://www1.eere.energy.gov/buildings/ssl/techroadmaps.html . 6 Karlicek RF Jr ( 2005 ) Conference on Lasers and Electro-optics...

Hoon-sik Kim; Eric Brueckner; Jizhou Song; Yuhang Li; Seok Kim; Chaofeng Lu; Joshua Sulkin; Kent Choquette; Yonggang Huang; Ralph G. Nuzzo; John A. Rogers

2011-01-01T23:59:59.000Z

437

Liquid-Phase Gallium–Indium Alloy Electronics with Microcontact Printing  

Science Journals Connector (OSTI)

The microcontact printer is composed of a print head mounted to a three-axis Cartesian robot. ... (9) Potential applications include soft and stretchable electronics for wearable technologies that monitor human motion(18-20) and electronic skin for biologically inspired soft robots. ... A paint brush is used to ink the stamps with a coat of liquid-phase GaIn alloy. ...

Arya Tabatabai; Andrew Fassler; Claire Usiak; Carmel Majidi

2013-04-30T23:59:59.000Z

438

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting  

Science Journals Connector (OSTI)

...of Materials Science and Engineering...Mechanical and Aerospace Engineering...energy. Further advances in this technology...that extend our recent work in flexible electronics...of Materials Sciences under Award...funded by National Science Foundation...energy. Further advances in this technology...

Hoon-sik Kim; Eric Brueckner; Jizhou Song; Yuhang Li; Seok Kim; Chaofeng Lu; Joshua Sulkin; Kent Choquette; Yonggang Huang; Ralph G. Nuzzo; John A. Rogers

2011-01-01T23:59:59.000Z

439

Radiation-Hardened Gallium Nitride Detector and Arrays for Fusion Diagnostics  

SciTech Connect (OSTI)

This poster reports testing to confirm that GaN devices exhibit the extreme radiation hardness needed for use at the NIF, functioning properly after 1x10{sup 12} protons/cm{sup 2} proton irradiation in one year.

Sun, K. X., and MacNeil, L.

2011-09-08T23:59:59.000Z

440

SAGE: Solar Neutrino Data from SAGE, the Russian-American Gallium Solar Neutrino Experiment  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

SAGE is a solar neutrino experiment based on the reaction 71Ga + n goes to 71Ge + e-. The 71Ge atoms are chemically extracted from a 50-metric ton target of Ga metal and concentrated in a sample of germane gas mixed with xenon. The atoms are then individually counted by observing their decay back to 71Ga in a small proportional counter. The distinguishing feature of the experiment is its ability to detect the low-energy neutrinos from proton-proton fusion. These neutrinos, which are made in the primary reaction that provides the Sun's energy, are the major component of the solar neutrino flux and have not been observed in any other way. To shield the experiment from cosmic rays, it is located deep underground in a specially built facility at the Baksan Neutrino Observatory in the northern Caucasus mountains of Russia. Nearly 100 measurements of the solar neutrino flux have been made during 1990-2000, and their combined result is a neutrino capture rate that is well below the prediction of the Standard Solar Model. The significant suppression of the solar neutrino flux that SAGE and other solar neutrino experiments have observed gives a strong indication for the existence of neutrino oscillations. [copied from the SAGE homepage at http://ewi.npl.washington.edu/SAGE/SAGE.html

SAGE Collaboration

Note: This page contains sample records for the topic "gallium arsenide gaas" 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

Identification of a physical metallurgy surrogate for the plutonium—1 wt.?% gallium alloy  

Science Journals Connector (OSTI)

Future plutonium research is expected to be limited due to the downsizing of the nuclear weapons complex and an industry focus on environmental remediation and decommissioning of former manufacturing and research facilities. However the need to further the understanding of the behavior of plutonium has not diminished. Disposition of high level residues long-term storage of wastes and certification of the nuclear stockpile through the Stockpile Stewardship Program are examples of the complex issues that must be addressed. Limited experimental facilities and the increasing cost of conducting plutonium research provide a strong argument for the development of surrogate materials. The purpose of this work was to identify a plutonium surrogate based on fundamental principles such as electronic structure and then to experimentally demonstrate its viability.

Frank E. Gibbs; David L. Olson; William Hutchinson

2000-01-01T23:59:59.000Z

442

Accelerated Testing of HT-9 with Zirconia Coatings Containing Gallium using Raman Spectroscopy and XPS  

SciTech Connect (OSTI)

Laser Raman spectroscopy and x-ray photoelectron spectroscopy were used to study the evolution of composition of oxide films in the presence of zirconia coatings on miniature HT-9 alloy specimens subjected to elevated temperature in air. The experiments expanded on previous efforts to develop a quick-screening technique for candidate alloys for cladding materials (HT-9) and actinide-based mixed oxide fuel mixtures (represented by the zirconia coating) by investigating the effect of both coating composition and alloy pretreatment conditions on the high temperature reactions. In particular, the presence of the element Ga (a potential impurity in mixed oxide fuel) in the initial zirconia coating was found to accelerate the rate of oxide growth relative to that of yttria-stabilized zirconia studied previously. In addition, HT-9 samples that were subjected to different thermal pretreatments gave different results. The results suggest that the presence of Ga in a mixed oxide fuel will enhance the corrosion of HT-9 cladding under the conditions of this study, although the extent of enhancement is influenced by thermal pretreatment of the cladding material. The results also demonstrate the need to combine Raman spectroscopy with other techniques, particularly photoelectron spectroscopy, for optimizing composition and/or fabrication conditions of both cladding and oxide fuels for advanced nuclear reactors.

Windisch, Charles F.; Henager, Charles H.; Engelhard, Mark H.; Bennett, Wendy D.

2009-12-01T23:59:59.000Z

443

Gallium-68 Bioorthogonal Tetrazine Polymers for the Multistep Labeling of Cancer Biomarkers /  

E-Print Network [OSTI]

M, Fox JM (2008) Tetrazine ligation: fast bioconjugationR, Hilderbrand SA (2008) Tetrazine-Based Cycloadditions:of Cancer Cells through a Tetrazine/trans- Cyclooctene

Nichols, Brandon Edward

2013-01-01T23:59:59.000Z

444

Thermodynamic properties of gallium hydroxide oxide (alpha -GaOOH) at temperatures to 700 K  

Science Journals Connector (OSTI)

...periodically removed from the reactor at the experimental temperature...titanium filter inserted in the reactor cover. Each sample was divided...and V. Pokrovskii greatly improved the presentation and clarity...doctorat, Universit Paul-Sabatier de Toulouse, 166 p. Diakonov...

Gleb S. Pokrovski; Igor I. Diakonov; Pascale Benezeth; Vyacheslav M. Gurevich; Konstantin S. Gavrichev; Vadim E. Gorbunov; Jean-Louis Dandurand; Jacques Schott; Igor L. Khodakovsky

445

Professor Mathias Schubert explains his study of indium gallium nitride semiconductor systems, which  

E-Print Network [OSTI]

generation of multiple-junction solar energy conversion devices with improved ease of manufacture, cost within a sample. Conversely, the blue light-emitting diodes (LEDs) intended for transferring from energy free charge carrier properties in contact- based electrical measurements, in the extreme case

Farritor, Shane

446

Testing the Reactor and Gallium Anomalies with Intense (Anti)Neutrino Emitters  

E-Print Network [OSTI]

Several observed anomalies in neutrino oscillation data could be explained by a hypothetical fourth neutrino separated from the three standard neutrinos by a squared mass difference of a few 0.1 eV$^2$ or more. This hypothesis can be tested with MCi neutrino electron capture sources ($^{51}$Cr) or kCi antineutrino $\\beta$-source ($^{144}$Ce) deployed inside or next to a large low background neutrino detector. In particular, the compact size of this source coupled with the localization of the interaction vertex lead to an oscillating pattern in event spatial (and possibly energy) distributions that would unambiguously determine neutrino mass differences and mixing angles.

Th. Lasserre

2012-09-23T23:59:59.000Z

447

Temperature dependence of plasmonic terahertz absorption in grating-gate gallium-nitride transistor structures  

Science Journals Connector (OSTI)

Strong plasmon resonances have been observed in the terahertz transmission spectra (1–5 THz) of large-area slit-grating-gate AlGaN/GaN-based high-electron-mobility transistor(HEMT) structures at temperatures from 10 to 170 K. The resonance frequencies correspond to the excitation of plasmons with wave vectors equal to the reciprocal lattice vectors of the metal grating which serves both as a gate electrode for the HEMT and a coupler between plasmons and incident terahertz radiation. Wide tunability of the resonances by the applied gate voltage demonstrates potential of these devices for terahertz applications.

A. V. Muravjov; D. B. Veksler; V. V. Popov; O. V. Polischuk; N. Pala; X. Hu; R. Gaska; H. Saxena; R. E. Peale; M. S. Shur

2010-01-01T23:59:59.000Z

448

Picosecond response of gallium-nitride metal–semiconductor–metal photodetectors  

Science Journals Connector (OSTI)

Metal–semiconductor–metal ultraviolet photodiodes fabricated on GaN were tested in the picosecond regime with an electro-optic sampling system. A device with a feature size of 1 ?m showed a response with 1.4 ps rise time and 3.5 ps full width at half maximum. The derived electron velocity 1.43×10 7 ? cm/s is in good agreement with independent photoexcitation measurements. A slower impulse response was observed in a device with smaller feature size of 0.5?? m .

Jianliang Li; Ying Xu; T. Y. Hsiang; W. R. Donaldson

2004-01-01T23:59:59.000Z

449

Control of the emission wavelength of gallium nitride-based nanowire light-emitting diodes.  

E-Print Network [OSTI]

??Halbleiter-Nanosäulen (auch -Nanodrähte) werden als Baustein für Leuchtdioden (LEDs) untersucht. Herkömmliche LEDs aus Galliumnitrid (GaN) bestehen aus mehreren Kristallschichten auf einkristallinen Substraten. Ihr Leistungsvermögen wird… (more)

Wölz, Martin

2013-01-01T23:59:59.000Z

450

E-Print Network 3.0 - analysis gallium-67 lung Sample Search...  

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

ILD... , interstitial lung disease, texture analysis, co-occurrence matrix, computed tomography I. INTRODUCTION Computer... %. The aim of our work is to develop a novel texture ......

451

Gallium solar neutrino experiments: Absorption cross sections, neutrino spectra, and predicted event rates  

E-Print Network [OSTI]

solar neutrino sources with standard energy spectra, and for laboratory sources of 51 Cr and 37 Ar; the calculations include, where appropriate, the thermal energy of fusing solar ions and use improved nuclear the energy spectrum of solar neutrinos. Theoretical uncertainties are estimated for cross sections

Bahcall, John

452

Lattice distortions in layered type arsenides LnTAs{sub 2} (Ln=La-Nd, Sm, Gd, Tb; T=Ag, Au): Crystal structures, electronic and magnetic properties  

SciTech Connect (OSTI)

The lanthanide coinage-metal diarsenides LnTAs{sub 2} (Ln=La, Ce-Nd, Sm; T=Ag, Au) have been reinvestigated and their structures have been refined from single crystal X-ray data. Two different distortion variants of the HfCuSi{sub 2} type are found: PrAgAs{sub 2}, NdAgAs{sub 2}, SmAgAs{sub 2}, GdAgAs{sub 2}, TbAgAs{sub 2}, NdAuAs{sub 2} and SmAuAs{sub 2} crystallize as twofold superstructures in space group Pmcn with the As atoms of their planar layers forming zigzag chains, whereas LaAgAs{sub 2}, CeAgAs{sub 2} and PrAuAs{sub 2} adopt a fourfold superstructure (space group Pmca) with cis-trans chains of As atoms. The respective atomic positions can be derived from the HfCuSi{sub 2} type by group-subgroup relations. The compounds with zigzag chains of As atoms exhibit metallic behaviour while those with cis-trans chains are semiconducting as measured on powder pellets. The majority of the compounds including 4f elements show antiferromagnetic ordering at T{sub N}<20 K. - Text3: Zigzig vs. cis-trans.

Rutzinger, D.; Bartsch, C. [Anorganische Chemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, D-01062 Dresden (Germany); Doerr, M. [Institut fuer Festkoerperphysik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Rosner, H. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Noethnitzer Str. 40, D-01187 Dresden (Germany); Neu, V. [IFW Dresden, Institut fuer metallische Werkstoffe, Helmholtzstr. 20, D-01069 Dresden (Germany); Doert, Th., E-mail: thomas.doert@chemie.tu-dresden.d [Anorganische Chemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, D-01062 Dresden (Germany); Ruck, M. [Anorganische Chemie, Fachrichtung Chemie und Lebensmittelchemie, Technische Universitaet Dresden, D-01062 Dresden (Germany)

2010-03-15T23:59:59.000Z

453

Geochemistry of arsenic and metals in stored tailings of a Co–Ni arsenide-ore, Khovu-Aksy area, Russia  

Science Journals Connector (OSTI)

Interest in the redistribution of As-bearing species during long-term storage of hydrometallurgical tailings is motivated partly by the need to prevent As from being released into the environment. The speciation of As in mine wastes from the Tuva Cobalt Plant (Khovu-Aksy mine site, Tuva Republic, Russia) has been studied using mineralogical techniques, and chemical analyses of solids (tailings, soils, vegetation) and solutions (recovered pore waters, leach solutions). Ore at the plant was processed by hot autoclave leaching with an ammoniacal carbonate solution followed by treatment with CO2(gas) and caustic magnesite, MgO. Pronounced differences in element concentrations were measured in the five separate tailings ponds and one trench that were filled sequentially during operation of the plant. The concentration of each element was relatively uniform within each pond but the correlations among solid-phase Co, Ni, Zn and Cu gradually decrease from the most recent to oldest ponds as does the correlation between solid-phase As, Ag, Cd and Pb. In the oldest ponds, significant correlations are present between solid-phase Fe–As, Fe–Sb and Fe–Zn. High carbonate content in the ores and leaching reagents control the pH of the pore waters (pH = 7.27–9.10) where the major cation is Ca2+, followed by NH 4 + and Mg2+. Concentrations of As in pore solutions reach up to 140 mg L?1, and average 15 mg L?1. The high pore-water As concentrations are a consequence of instability of the processing residues, which include Mg(NH4)AsO4?nH2O and Mg3(AsO4)2?nH2O. The concentrations of Zn, Cu and As in pore waters increase from the youngest pond to the oldest storage impoundment (trench), which is evidence of the increase in element mobility with time. In contrast to the metals, As is preferentially sorbed to Fe oxides formed in the tailings. Aerosol transport of dust from the dry ponds has produced anomalies of As and metals in the surrounding area with As in the most polluted soils reaching up to 540 ppm. Moreover, vegetation growing on the surface of the disposal ponds absorbs solutes from the soil.

S. Bortnikova; E. Bessonova; O. Gaskova

2012-01-01T23:59:59.000Z

454

Ultrafast gating of proximity-focused microchannel-plate intensifiers  

SciTech Connect (OSTI)

Proximity-focused, microchannel-plate (MCP) image intensifiers have been used at Los Alamos for many years to allow single frame film and video exposure times in the range of 2.5 to 10 ns. There is now a program to reduce gating times to < 1 ns. This paper reviews previous work and the problems in achieving good resolution with gating times of < 1 ns. The key problems involve applying fast electrical gating signals to the tube elements. We present computer modeling studies of the combined tube, tube connection, and pulser system and show that low photocathode surface resistivity must be obtained to permit fast gating between the photocathode and the MCP input. We discuss ways of making low-resistivity S20 photocathodes, using gallium arsenide photocathodes, and various means of gating the tubes. A variety of pulser designs are being experimentally evaluated including spark gaps, avalanche transistors, Krytron tubes with sharpening gaps, step recovery diodes, and photoconductive elements (PCEs). The results of these studies are presented. Because of the high capacitances involved in most gating schemes, the tube connection geometry must be of low-impedance design, and our solution is presented. Finally, ways of testing these high-speed camera systems are discussed.

Lundy, A.S.; Iverson, A.E.

1982-01-01T23:59:59.000Z

455

Solar?energy conversion at high solar intensities  

Science Journals Connector (OSTI)

The concentration of sunlight offers distinct advantages for solar–electrical generation either by thermal conversion or by photovoltaics. A large variety of concentration techniques are available with concentration ratios of 1–1000. Concentration is required for thermal conversion systems to attain the high temperatures needed for efficiencies in the desired range of about 25%–35%. The projected costs for some of the solar thermal systems (especially the central receiver and the fixed mirror) indicate that they could be economically competitive in the southwestern states. The southwest may be required for these high?concentration systems to overcome the main disadvantage of concentration which is the use of the direct component of sunlight only. Other concerns of high?intensity systems are in tracking requirements reflective surface accuracy and material lifetimes of both the reflecting and absorbing components. Selective surface absorbers will be required for systems with concentration ratios below a few hundred. The present high cost of solar?cell?generated electricity can be reduced considerably by using concentrators. Cells can be used with any of the concentrator designs and the major concern is keeping them at acceptable operating temperatures. Planar silicon cells vertical multijunction and gallium–aluminum–arsenide cells all look attractive for concentrating systems.

Charles E. Backus

1975-01-01T23:59:59.000Z

456

Production data on 0.55 eV InGaAs thermophotovoltaic cells  

SciTech Connect (OSTI)

Low bandgap 0.55 eV (2.25 {micro}m cutoff wavelength) indium gallium arsenide (In{sub 0.72}Ga{sub 0.28}As) thermophotovoltaic (TPV) cells use much more of the long wavelength energy emitted from low temperature (< 1,200 C) thermal sources than either Si or GaSb cells. Data are presented on a statistically significant number (2,500) of these TPV cells, indicating the performance obtainable in large numbers of cells. This data should be useful in the design and modeling of TPV system performance. At 1.2 A/cm{sup 2} short-circuit current, an average open-circuit voltage of 283 mV is obtained with a 60% fill factor. The peak external quantum efficiency for uncoated cells is 65% and is over 50% from 1.1 to 2.2 {micro}m. Internal quantum efficiency is over 76% in this range assuming an estimated 34% reflectance loss.

Wojtzuk, S.; Colter, P. [Spire Corp., Bedford, MA (United States); Charache, G.; Campbell, B. [Lockheed Martin, Inc., Schenectady, NY (United States)

1996-05-01T23:59:59.000Z

457

Bestimmung von zink in salzsäure, galliumarsenid und galliumaluminiumarsenid durch flammenlose atomabsorption  

Science Journals Connector (OSTI)

Zusammenfassung Ein Eigenbau-AAS-Gerät und Kohlenstabatomisator wurden verwendet und hier beschrieben. Die apparativen Parameter wurden optimiert. Der Einfluß der Matrix auf die Empfindlichkeit der Bestimmung sowie die Ursachen der unspezifischen Absorption werden diskutiert. Die Nachweisgrenze der Methode liegt je nach Bedingungen bei 2–25 × 10?11g bzw. 3–20 ppM bezogen auf 1 ml 1M Salzsäure oder 2,5–30 ppm bezogen auf 0,1–1 mg Galliumarsenid. A home-made AAS-instrument and a home-made carbon-rod atomizer are described. The instrumental parameters were optimized. The influence of the matrix on the sensitivity, and the reasons for non-specific absorption are discussed. The detection limit of the method is 2–25 × 10?11g or 3–20 ppM relative to 1 ml of 1M hydrochloric acid or 2.5–30 ppm relative to 0.1–1 mg of gallium arsenide.

K. Dittrich; W. Zeppan

1975-01-01T23:59:59.000Z

458

Ebic Investigation of the Recombination at the Edges of GaAs Solar Cells  

Science Journals Connector (OSTI)

Intermediate band photovoltaics is one of the so-called third generation photovoltaic device designs proposed to increase the efficiency of solar cells. It involves the creation of an intermediate ... traditional...

Andrea Scaccabarozzi; M. Acciarri

2013-01-01T23:59:59.000Z

459

Adsorption Kinetics of Hydrogen Sulfide and Thiols on GaAs (001) Surfaces in a Vacuum  

Science Journals Connector (OSTI)

For instance, a p(2 × 2) LEED structure, achieved upon repeated exposure to thiol and annealing to 750 K,9 implies that the surface concentration of chemisorbed sulfur could reach 0.25 monolayers. ... Funding for this research was provided by the Canadian Institutes for Health Research and the Canada Research Chair Program. ...

Oleksandr Voznyy; Jan J. Dubowski

2008-02-20T23:59:59.000Z

460

E-Print Network 3.0 - algaas-gaas issledovanie ehnergeticheskikh...  

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

4 A COMPLETION CONJECTURE FOR KIRKMAN TRIPLE SYSTEMS Summary: BF A.M.Baraev, I.A.Faradzhev, Postroenie i issledovanie na EVM odnorodnykh i odnorod- nykh dvudol Source: Franek,...

Note: This page contains sample records for the topic "gallium arsenide gaas" 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.


461

Corrosion-induced degradation of GaAs PHEMTs under operation in high humidity conditions  

E-Print Network [OSTI]

We have comprehensively investigated the degradation mechanism of AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors (PHEMTs) under operation in high humidity conditions. PHEMTs degradation under high humidity ...

Hisaka, Takayuki

462

Weak localization of dilute 2D electrons in undoped GaAs heterostructures.  

SciTech Connect (OSTI)

The temperature dependence of the resistivity and magnetoresistance of dilute 2D electrons are reported. The temperature dependence of the resistivity can be qualitatively described through phonon and ionized impurity scattering. While the temperature dependence indicates no ln(T) increase in the resistance, a sharp negative magnetoresistance feature is observed at small magnetic fields. This is shown to arise from weak localization. At very low density, we believe weak localization is still present, but cannot separate it from other effects that cause magnetoresistance in the semi-classical regime.

Seamons, John Andrew; Lilly, Michael Patrick; Reno, John Louis; Bielejec, Edward Salvador

2004-07-01T23:59:59.000Z

463

A study of microstrip T-juction discontinuity effects and modeling on GAAS substrates  

E-Print Network [OSTI]

. . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . 2 Microstrip T-junction discontinuity. . Microstrip T-junction geometry's. (a) symmetrical, (b) nonsymmetrical. . . . . . . . . . . . 4 Transmission line equivalent circuit model for a lossless T-junction. . . . S? for an ideal 3 port... transmission lines and structures. Through decades of research, analysis and measurement the electrical properties of micmstrip transmission lines can be calculated and predicted with great accuracy. However any variation &om a longitudinally straight...

Guill, Dennis Jarrett

2012-06-07T23:59:59.000Z

464

The design of GaAs HEMT and HBT Bessel-type transimpedance amplifiers  

E-Print Network [OSTI]

gain, and oo f?? 2= is bandwidth of the TIA represented by the transfer function H(s). Using Simulink, the output voltage V o in response to an input current at 1 bit/s is plotted for several values of the bandwidth , varying from 0.1Hz to 1Hz... gain, and oo f?? 2= is bandwidth of the TIA represented by the transfer function H(s). Using Simulink, the output voltage V o in response to an input current at 1 bit/s is plotted for several values of the bandwidth , varying from 0.1Hz to 1Hz...

Adeyemi, Oluwafemi Ibukunoluwa

2007-04-25T23:59:59.000Z

465

Investigation of the semiconductor–oxide electrolyte interface in GaAs utilizing electrolyte electroreflectance  

Science Journals Connector (OSTI)

We have investigated the electrolyte electroreflectance (EER) spectra of N–GaAs in the vicinity of the E o transition (direct gap at k?=0). A pronounced interference phenomenon sensitive to the d c b i a s e l e c t r i c f i e l d has been observed which we identify with an exciton quenching effect within the semiconductor space–charge region (SCR). We have utilized this excitonic feature to interferometrically probe the dynamic and steady?state properties of the SCR during electrochemical anodization procedures. The same EER spectra also exhibit Franz–Keldysh oscillations the period of which is explicitly dependent on the a c e l e c t r i c f i e l d. Using these phenomena we have shown that the interfacial and oxide electric fields under steady?state conditions are just sufficient to continue growing the oxide in compensation for slow dissolution. If the dc bias voltage is suddenly reduced the SCR temporarily collapses due to transient effects which we attribute to very slow interface states in the oxide. These techniques are applicable to the study of the SCR in a variety of semiconductor–electrolyte systems as well as in the Schottky barrier configuration.

R. P. Silberstein; F. H. Pollak

1980-01-01T23:59:59.000Z

466

GaAs on Si,,111...--crystal shape and strain relaxation in nanoscale patterned growth  

E-Print Network [OSTI]

electrolysis makes Cl2 C & F react to make CF4 & C2F6 C & Cl in presence of O dioxins? furans? #12;Sadoway, MIT

New Mexico, University of

467

Excitation-Dependent Recombination and Diffusion Near an Isolated Dislocation in GaAs  

SciTech Connect (OSTI)

In low-magnification, plan-view photoluminescence images of a nominally lattice-matched, undoped GaAs/GaInP heterostructure, we observe a random distribution of isolated dark spots. We attribute the dark spots to crystal dislocations, where nonradiative recombination is augmented by transitions utilizing defect-related energy levels between the conduction and valence bands. We note that, when the laser excitation intensity is reduced, the darkened regions expand. At lower excitation, the density of photogenerated electrons and holes is reduced, and they are more likely to reach the defective region before encountering a partner for radiative recombination. When we model the behavior with a simulation that allows for Laplacian diffusion and defect-related recombination only through mid-bandgap energy levels, we do not obtain good agreement between experimental and simulated images. But if we allow for an arbitrary distribution of defect levels, such that the occupation of the levels and bands can change independently, we have more flexibility for fitting the density-dependent recombination rates. The more sophisticated model produces results that are more consistent with experimental images.

Gfroerer, T. H.; Crowley, C. M.; Read, C. M.; Wanlass, M. W.

2012-06-01T23:59:59.000Z

468

Recent improvements in materials for thin GaAs and multibandgap solar cells  

SciTech Connect (OSTI)

The High Efficiency Concepts Program at SERI supports research on III-V compound semiconductors with the objective of achieving the maximum attainable photovoltaic conversion efficiencies for terrestrial solar electric power. The outcome of this research may also affect the future of space photovoltaic cells. While the interest in thin-film, high-efficiency solar cells for terrestrial applications is driven principally by consideration of system costs, such cells would also improve the power density of space power arrays.

Benner, J.P.

1985-05-01T23:59:59.000Z

469

Fourier spectroscopy of individual nitrogen impurity centers in GaAs  

SciTech Connect (OSTI)

We report on the measurement of the exciton homogeneous linewidth in nitrogen impurity centers in GaAs:N. Fourier spectroscopy on a single center revealed a long coherence time over 300 ps at low temperature. The narrowest linewidth obtained at liquid helium temperature is 3.5 ?eV, which is comparable with that of semiconductor quantum dots. The linewidth increases with increasing temperature, showing a thermally activated behavior with activation energies of 2?5 meV.

Ikezawa, Michio [PRESTO-JST, JST, Kawaguchi, Japan and Institute of Physics, University of Tsukuba, Tsukuba (Japan); Zhang, Liao; Mori, Tatsuya; Masumoto, Yasuaki [Institute of Physics, University of Tsukuba, Tsukuba (Japan); Sakuma, Yoshiki; Sakoda, Kazuaki [National Institute for Materials Science, Tsukuba (Japan)

2013-12-04T23:59:59.000Z

470

Simulations of Atomic Processes at Semiconductor Surfaces - General-Method and Chemisorption on Gaas(110)  

E-Print Network [OSTI]

& F(r)= ?2a ~ V(r) ( +py(r), (2.15) BU,)F"=? (2.22) so the strength of the electronic force is determined by the interatomic matrix element V(r) and its dependence on the separation of the atoms r. The equilibrium separation is given by 2a ~ V..., but Si bonding at the As?As bridge site 2. Notice that the x vibrations of Si have higher fre- quency than those of C, even though Si is a heavier atom. The reason, of course, is that Si sits between two As atoms, above the surface, and experiences...

MENON, M.; Allen, Roland E.

1988-01-01T23:59:59.000Z

471

Copper Doped GaAs Infrared Filter for the 8-13 m Atmospheric Window  

E-Print Network [OSTI]

regions of interest, such as atmospheric transmission windows. Filters exclude solar or thermal photonsCdTe is typically melt grown in a high temperature furnace. All three elements in this alloy are toxic. Stability

Peale, Robert E.

472

Electron transport in confined structures in very high mobility GaAs in perpendicular magnetic fields  

E-Print Network [OSTI]

In this thesis we study properties of two-dimensional electron transport through constrictions in perpendicular magnetic fields. We present two sets of experiments, one focusing on properties in the integer quantum Hall ...

Radu, Iuliana

2009-01-01T23:59:59.000Z

473

High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrator Application  

SciTech Connect (OSTI)

The High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrators project seeks to provide new photovoltaic cells for Concentrator Photovoltaics (CPV) Systems with higher cell efficiency, more favorable temperature coefficients and less sensitivity to changes in spectral distribution. The main objective of this project is to provide high efficiency III-V solar cells that will reduce the overall cost per Watt for power generation using CPV systems.This work is focused both on a potential near term application, namely the use of indium arsenide (InAs) QDs to spectrally "tune" the middle (GaAs) cell of a SOA triple junction device to a more favorable effective bandgap, as well as the long term goal of demonstrating intermediate band solar cell effects. The QDs are confined within a high electric field i-region of a standard GaAs solar cell. The extended absorption spectrum (and thus enhanced short circuit current) of the QD solar cell results from the increase in the sub GaAs bandgap spectral response that is achievable as quantum dot layers are introduced into the i-region. We have grown InAs quantum dots by OMVPE technique and optimized the QD growth conditions. Arrays of up to 40 layers of strain balanced quantum dots have been experimentally demonstrated with good material quality, low residual stain and high PL intensity. Quantum dot enhanced solar cells were grown and tested under simulated one sun AM1.5 conditions. Concentrator solar cells have been grown and fabricated with 5-40 layers of QDs. Testing of these devices show the QD cells have improved efficiency compared to baseline devices without QDs. Device modeling and measurement of thermal properties were performed using Crosslight APSYS. Improvements in a triple junction solar cell with the insertion of QDs into the middle current limiting junction was shown to be as high as 29% under one sun illumination for a 10 layer stack QD enhanced triple junction solar cell. QD devices have strong potential for net gains in efficiency at high concentration.

Hubbard, Seth

2012-09-12T23:59:59.000Z

474

Accelerated Testing of HT-9 with Zirconia Coatings Containing...  

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

Testing of HT-9 with Zirconia Coatings Containing Gallium using Raman Spectroscopy and XPS. Accelerated Testing of HT-9 with Zirconia Coatings Containing Gallium using Raman...

475

Monday, December 13, 1999 Physics Today On The Web -Physics Update Page: 1 http://www.aip.org/pt/nov99/physup1199.htm  

E-Print Network [OSTI]

, but with ratios of boron-10 to boron-11 and of gallium-69 to gallium-71 that exceeded the natural abundances

Pierrehumbert, Raymond

476

Structure, Morphology, and Optical Properties of Amorphous and...  

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

Morphology, and Optical Properties of Amorphous and Nanocrystalline Gallium Oxide Thin Films. Structure, Morphology, and Optical Properties of Amorphous and Nanocrystalline Gallium...

477

Novel methods of hydrogen production: aluminum-gallium-indium-tin systems and copper boron oxide as photocatalysts.  

E-Print Network [OSTI]

??In recent years, hydrogen production and storage has attracted a lot of attention in both academia and industry due to its variety of applications in… (more)

Lang, Yizhao

2011-01-01T23:59:59.000Z

478

Physics based analytical modelling of Gallium Nitride(GaN) MESFET considering different ion implantation energy with high temperature annealing.  

E-Print Network [OSTI]

??A physics based analytical model of ion implanted GaN MESFET has been presented considering high temperature annealing effects. Choosing appropriate activation energy of impurity atoms,… (more)

Raghavan, Vinay

2015-01-01T23:59:59.000Z

479

The radiation bio-effects of gallum-72 on leukemic cells via a gallium-transferrin complex  

E-Print Network [OSTI]

of the beta is about 30'/o to 40'/o of the maximum energy. An anti-neutrino is emitted simultaneously, carrying the remainder of the energy. Values listed for beta energies are the maximum values unless otherwise stated (Cember 1996). Prominent beta...

Forbes, Christen Douglas

2012-06-07T23:59:59.000Z

480

The design, construction, and testing of a nuclear fuel rod thermal simulation system to study gallium/Zircaloy interactions  

E-Print Network [OSTI]

friends for their unending support and patience during this project. Thank you so much! NOMENCLATURE Abbreviations and Acronyms WGPu- weapons grade plutonium DOE- Department of Energy MOX- mixed oxide fuel WG MOX- weapons grade MOX fuel LWR- light... to be employed were immobilization and fissioning the WGPu as mixed oxide (MOX) fuel in commercial power reactors. Both approaches have many advantages and disadvantages and are currently being studied by scientists and engineers all over the world. The use...

Allison, Christopher Curtis

2012-06-07T23:59:59.000Z

Note: This page contains sample records for the topic "gallium arsenide gaas" 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.


481

Comparative band alignment of plasma-enhanced atomic layer deposited high-k dielectrics on gallium nitride  

SciTech Connect (OSTI)

Al{sub 2}O{sub 3} films, HfO{sub 2} films, and HfO{sub 2}/Al{sub 2}O{sub 3} stacked structures were deposited on n-type, Ga-face, GaN wafers using plasma-enhanced atomic layer deposition (PEALD). The wafers were first treated with a wet-chemical clean to remove organics and an in-situ combined H{sub 2}/N{sub 2} plasma at 650 Degree-Sign C to remove residual carbon contamination, resulting in a clean, oxygen-terminated surface. This cleaning process produced slightly upward band bending of 0.1 eV. Additional 650 Degree-Sign C annealing after plasma cleaning increased the upward band bending by 0.2 eV. After the initial clean, high-k oxide films were deposited using oxygen PEALD at 140 Degree-Sign C. The valence band and conduction band offsets (VBOs and CBOs) of the Al{sub 2}O{sub 3}/GaN and HfO{sub 2}/GaN structures were deduced from in-situ x-ray and ultraviolet photoemission spectroscopy (XPS and UPS). The valence band offsets were determined to be 1.8 and 1.4 eV, while the deduced conduction band offsets were 1.3 and 1.0 eV, respectively. These values are compared with the theoretical calculations based on the electron affinity model and charge neutrality level model. Moreover, subsequent annealing had little effect on these offsets; however, the GaN band bending did change depending on the annealing and processing. An Al{sub 2}O{sub 3} layer was investigated as an interfacial passivation layer (IPL), which, as results suggest, may lead to improved stability, performance, and reliability of HfO{sub 2}/IPL/GaN structures. The VBOs were {approx}0.1 and 1.3 eV, while the deduced CBOs were 0.6 and 1.1 eV for HfO{sub 2} with respect to Al{sub 2}O{sub 3} and GaN, respectively.

Yang Jialing; Eller, Brianna S.; Zhu Chiyu; England, Chris; Nemanich, Robert J. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

2012-09-01T23:59:59.000Z

482

Precursors for formation of copper selenide, indium selenide, copper indium diselenide, and/or copper indium gallium diselenide films  

DOE Patents [OSTI]

Liquid-based precursors for formation of Copper Selenide, Indium Selenide, Copper Indium Diselenide, and/or copper Indium Galium Diselenide include copper-organoselenides, particulate copper selenide suspensions, copper selenide ethylene diamine in liquid solvent, nanoparticulate indium selenide suspensions, and indium selenide ethylene diamine coordination compounds in solvent. These liquid-based precursors can be deposited in liquid form onto substrates and treated by rapid thermal processing to form crystalline copper selenide and indium selenide films.

Curtis, Calvin J; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S

2014-11-04T23:59:59.000Z

483

Silicon-germanium/gallium phosphide material in high power density thermoelectric modules. Final report, February 1980--September 1981  

SciTech Connect (OSTI)

This is the final report of work on the characterization of an improved Si-Ge alloy and the fabrication of thermoelectric devices. The improved Si-Ge alloy uses a small addition of GaP in n- and p- type 80 at.% Si-20 at.% Ge; this addition reduces the thermal conductivity, thereby increasing its figure of merit and conversion efficiency. The thermoelectric devices fabricated include multicouples intended for use in Radioisotope Thermoelectric Generators (RTGs) and ring-type modules intended for use with nuclear reactor heat sources. This report summarizes the effort in the material as well as the device areas and discusses individual phases of each area. Results should form basis for further effort.

Not Available

1981-12-31T23:59:59.000Z

484

Calpain-Mediated Integrin Deregulation as a Novel Mode of Action for the Anticancer Gallium Compound KP46  

Science Journals Connector (OSTI)

...processes, including the regulation of mRNA stability and translation, cellular proliferation...population as shown in Fig. 1A. A bubble plot can be used to depict both the abundance...in different cell populations. A, a bubble plot depicting the relative abundance...

Ute Jungwirth; Johannes Gojo; Theresa Tuder; Gernot Walko; Martin Holcmann; Thomas Schöfl; Karin Nowikovsky; Nastasia Wilfinger; Sushilla Schoonhoven; Christian R. Kowol; Rosa Lemmens-Gruber; Petra Heffeter; Bernhard K. Keppler; and Walter Berger

2014-10-01T23:59:59.000Z

485

Temperature dependence of electrical properties of gallium-nitride bulk single crystals doped with Mg and their evolution with annealing  

Science Journals Connector (OSTI)

Comprehensive studies of the electrical properties of Mg-doped bulk GaN crystals grown by high-pressure synthesis were performed as a function of temperature up to 750?°C. Annealing of the samples in nitrogen ambient modifies qualitatively their resistivity values ? and the ?(T) variation. It was found that our material is characterized by a high concentration of oxygen-related donors and that the charge transport in the studied samples is determined by two types of states one of shallow character (Mg-related state E A ?0.15? eV ) and the second one much more deep E 2 ?0.95? eV (above the valence band). Depending on the effective concentration of either states different resistivities ? can be observed: lower resistivity (?10 6 ??? cm at ambient temperature) in samples with dominant E 2 states. For the first type of samples annealing at T ann <500?° C leads to a decrease of their resistivity and is associated with an increase of the effective concentration of the shallow Mg acceptors. Annealing of both types of samples at temperatures between 600 and 750?°C leads to an increase of the deep state concentration. The presence of hydrogen ambient during annealing of the low-resistivity samples strongly influences their properties. The increase of the sample resistivity and an appearance of a local vibrational mode of hydrogen at 3125 cm?1 were observed. These effects can be removed by annealing in hydrogen-free ambient.

E. Litwin-Staszewska; T. Suski; R. Piotrzkowski; I. Grzegory; M. Bockowski; J. L. Robert; L. Ko?czewicz; D. Wasik; E. Kami?ska; D. Cote; B. Clerjaud

2001-01-01T23:59:59.000Z

486

An experimental study of the solubility of Gallium(III) oxide in HCl-bearing water vapour  

E-Print Network [OSTI]

at 200 °C at a pH of $4. The values are very similar to those estimated from data for geothermal wells

Devernal, Anne

487

GALLIUM NITRIDE INTEGRATED GAS/TEMPERATURE SENSORS FOR FUEL CELL SYSTEM MONITORING FOR HYDROGEN AND CARBON MONOXIDE  

E-Print Network [OSTI]

on field effect devices using catalytic metal gates on silicon carbide substrates has been reviewed (Spetz-10%) of transition metals such as copper, silver, and chromium (Feinstein et al 1997 and Pyke 1993). High temperature. Introduction Gas sensing and analysis based on gas adsorption on a catalytic metal surface has been extensively

488

Evidence of electronic polarization of the As ion in the superconducting phase of F-doped LaFeAsO  

Science Journals Connector (OSTI)

Charge-carrier redistribution invoked by enhanced electronic polarization of the As ion was observed in the superconducting phase of iron arsenide.

Kim, J.

2014-04-14T23:59:59.000Z

489

Noncontact deep level photo-thermal spectroscopy: Technique and application to semi-insulating GaAs Wafers  

E-Print Network [OSTI]

to high resistivity materials, since the Debye-Huckel length is too large several milli- meters for semi materials. In DLPTS, the thermal recovery of carriers after excita- tion is monitored by a subNoncontact deep level photo-thermal spectroscopy: Technique and application to semi-insulating Ga

Mandelis, Andreas

490

SIMULATIONS OF A HIGH POWER 4H-SiC VJFET AND ITS GaAs COUNTERPART  

E-Print Network [OSTI]

of the two devices. The two-dimensional simulations were carried out using the ATLAS simulator from Silvaco

Myles, Charles W.

491

Projected Performance of Three- and Four-Junction Devices Using GaAs and GaInP  

E-Print Network [OSTI]

This paper explores the efficiencies expected for three- and four-junction devices for both space and terrestrial applications. For space applications, the effects of temperature and low concentration are investigated. For terrestrial applications, a concentration of 500 suns is assumed and the theoretical efficiencies are calculated as a function of spectral variations including the effects of air mass, turbidity, and water-vapor content. INTRODUCTION Ga 0.5 In 0.5 P/GaAs two-terminal, two-junction solar cells, invented and developed at the National Renewable Energy Laboratory, are in production at both TECSTAR and Spectrolab. The immediate market for these devices is in space; a future (potentially larger) market is terrestrial concentrator systems. The next-generation cells will add additional junction(s) in order to increase the efficiency. Work on a three-junction cell using an active Ge junction under the Ga 0.5 In 0.5 P/GaAs dual-junction cell has already been reported [1]. Ho...

Gainp; S. R. Kurtz; Sarah R. Kurtz; D. Myers; D. Myers; J.M. Olson; J. M. Olson

1997-01-01T23:59:59.000Z

492

Pseudomorphic growth of InAs on misoriented GaAs for extending quantum cascade laser wavelength  

SciTech Connect (OSTI)

The authors have studied the impact of epilayer strain on the deposition of InAs/GaAs on (100) and (111)B with 2° offset toward<2-1-1> surfaces. Consequences of a 7% lattice mismatch between these orientations in the form of three-dimensional growth are less apparent for (111)B with 2° offset toward<2-1-1> surfaces compared to (100). By exploring a range of molecular beam epitaxy process parameters for InAs/GaAs growth and utilizing scanning electron microscopy, atomic force microscopy, and Raman spectroscopy to evaluate the quality of these strained layers, the authors develop empirical models that describe the influence of the process conditions in regards to surface roughness with >92% accuracy. The smoothest InAs/GaAs samples demonstrated average surface roughness of 0.08 nm for 10 ?m{sup 2} areas, albeit at very low deposition rates. The authors have found the most important process conditions to be substrate temperature and deposition rate, leading us to believe that controlling diffusion length may be the key to reducing defects in severely strained structures. InGaAs/AlGaAs quantum cascade laser structures were also produced on (111)B with 2° offset toward<2-1-1> to take advantage of the piezoelectric effect, and the modified laser transitions due to these effects were observed.

Meyer, Charles; Cheng, Emily; Grayer, Justin; Mueller, David; Triplett, Gregory; Roberts, Denzil [Department of Electrical and Computer Engineering, University of Missouri, 349 Engineering Building West, Columbia, Missouri 65201 (United States)] [Department of Electrical and Computer Engineering, University of Missouri, 349 Engineering Building West, Columbia, Missouri 65201 (United States); Graham, Samuel [Georgia Institute of Technology, Woodruff School of Mechanical Engineering, Atlanta, Georgia 30332 (United States)] [Georgia Institute of Technology, Woodruff School of Mechanical Engineering, Atlanta, Georgia 30332 (United States)

2013-11-15T23:59:59.000Z

493

Si diffusion and segregation in low-temperature grown GaAs K. L. Kavanagh and J. C. P. Chang  

E-Print Network [OSTI]

spectroscopy (SIMS) using a Cs ion beam, and cross-sectional transmission electron micros- copy (TEM) using- files from SIMS data for a three layer LT-GaAs sample after anneals at 9-00"C for 10, 30 (forming gas

Woodall, Jerry M.

494

Cyclotron resonance to 100 mK of a GaAs heterojunction in the ultra-quantum limit  

Science Journals Connector (OSTI)

A helium dilution refrigerator has been modified to enable cyclotron resonance measurements to 100 mK on low-density, 2D electron systems in the ultra-quantum limit. Previous cyclotron resonance work to 300 mK indicates the presence of a phase boundary at a filling factor of vc?110, separating gas-like behavior at vmK, the system is spin polarized only at low values of v.

J.G. Michels; S. Hill; R.J. Warburton; G.M. Summers; P. Gee; J. Singleton; R.J. Nicholas; C.T. Foxon; J.J. Harris

1994-01-01T23:59:59.000Z

495

Kinetics of the inner ring in the exciton emission pattern in coupled GaAs quantum wells  

Science Journals Connector (OSTI)

We report on the kinetics of the inner ring in the exciton emission pattern. The formation time of the inner ring following the onset of the laser excitation is found to be about 30 ns. The inner ring is also found to disappear within 4 ns after the laser termination. The latter process is accompanied by a jump in the photoluminescence (PL) intensity. The spatial dependence of the PL jump indicates that the excitons outside of the region of laser excitation, including the inner ring region, are efficiently cooled to the lattice temperature even during the laser excitation. The ring formation and disappearance are explained in terms of exciton transport and cooling.

A. T. Hammack, L. V. Butov, J. Wilkes, L. Mouchliadis, E. A. Muljarov, A. L. Ivanov, and A. C. Gossard

2009-10-29T23:59:59.000Z

496

GaAs Clusters in the Quantum Size Regime: Growth on High Surface Area Silica by Molecular Beam Epitaxy  

Science Journals Connector (OSTI)

...cathodoluminescence ex-periments. Many useful comments on our manu-script were made by K. Kash, J. M. Worlock, and M. Saifi. We are especially gratefill to D. E. Aspnes for making concrete suggestions for the improvement ofour report. 8 May 1989...

C. J. SANDROFF; J. P. HARBISON; R. RAMESH; M. J. ANDREJCO; M. S. HEGDE; C. C. CHANG; E. M. VOGEL; D. M. HWANG

1989-07-28T23:59:59.000Z

497

High-quality quantum point contact in two-dimensional GaAs ,,311...A hole system  

E-Print Network [OSTI]

. R. Petta,2 and M. Shayegan1 1 Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA 2 Department of Physics, Princeton University, Princeton, New Jersey 08854, USA 40 nm deep, using an electron cyclotron resonance plasma etcher with ZEP 520A resist as an etch mask

Petta, Jason

498

On the Mass Eigenstate Composition of the 8B Neutrinos from the Sun  

E-Print Network [OSTI]

The present data of gallium experiments provide indirectly the only experimental limit on the fraction of $\

A. Kopylov; V. Petukhov

2006-08-14T23:59:59.000Z

499

Inelastic Neutron Scattering Study of a Nonmagnetic Collapsed Tetragonal Phase in Nonsuperconducting CaFe2As2: Evidence of the Impact of Spin Fluctuations on Superconductivity in the Iron-Arsenide Compounds  

SciTech Connect (OSTI)

The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the nonsuperconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is nonmagnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

Soh, Jing-Han [Ames Laboratory; Tucker, Ggregory S. [Ames Laboratory; Pratt, Daniel K. [Ames Laboratory; Abernathy, D. L. [Oak Ridge National Laboratory; Stone, M. B. [Oak Ridge National Laboratory; Ran, Sheng [Ames Laboratory; Budko, Sergey L. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory; Kreyssig, Andreas [Ames Laboratory; McQueeney, Robert J. [Ames Laboratory; Goldman, Alan I. [Ames Laboratory

2013-11-27T23:59:59.000Z

500

Inelastic neutron scattering study of a nonmagnetic collapsed tetragonal phase of CaFe2As2: Evidence of the impact of spin fluctuations on superconductivity in the iron-arsenide compounds.  

SciTech Connect (OSTI)

The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the non-superconducting collapsed tetragonal phase of CaFe2As2 via inelas- tic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetrag- onal phase of CaFe2As2 is non-magnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

Soh, Jing Han [ORNL] [ORNL; Tucker, G. S. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; Pratt, Daniel K [ORNL] [ORNL; Abernathy, Douglas L [ORNL] [ORNL; Stone, Matthew B [ORNL] [ORNL; Ran, S. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; Budko, S L [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; Canfield, P. C. [Ames Laboratory] [Ames Laboratory; Kreyssig, A. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; McQueeney, R. J. [Ames Laboratory] [Ames Laboratory; Goldman, A. I. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University

2013-01-01T23:59:59.000Z