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Sample records for aluminium gallium indium

  1. Toxicity of indium arsenide, gallium arsenide, and aluminium gallium arsenide.

    PubMed

    Tanaka, Akiyo

    2004-08-01

    Gallium arsenide (GaAs), indium arsenide (InAs), and aluminium gallium arsenide (AlGaAs) are semiconductor applications. Although the increased use of these materials has raised concerns about occupational exposure to them, there is little information regarding the adverse health effects to workers arising from exposure to these particles. However, available data indicate these semiconductor materials can be toxic in animals. Although acute and chronic toxicity of the lung, reproductive organs, and kidney are associated with exposure to these semiconductor materials, in particular, chronic toxicity should pay much attention owing to low solubility of these materials. Between InAs, GaAs, and AlGaAs, InAs was the most toxic material to the lung followed by GaAs and AlGaAs when given intratracheally. This was probably due to difference in the toxicity of the counter-element of arsenic in semiconductor materials, such as indium, gallium, or aluminium, and not arsenic itself. It appeared that indium, gallium, or aluminium was toxic when released from the particles, though the physical character of the particles also contributes to toxic effect. Although there is no evidence of the carcinogenicity of InAs or AlGaAs, GaAs and InP, which are semiconductor materials, showed the clear evidence of carcinogenic potential. It is necessary to pay much greater attention to the human exposure of semiconductor materials.

  2. Tetrahedral homonuclear organoelement clusters and subhalides of aluminium, gallium and indium

    NASA Astrophysics Data System (ADS)

    Uhl, Werner

    This review is focused on the synthesis and the reactivity of tetrahedral organoelement clusters of the heavier elements of third main-group aluminium, gallium, and indium, which have been known for about a decade. They possess the elements in an unusually low oxidation state of +1 and have direct element-element interactions between their four constituents. Each cluster atom is further attached to one terminal and in most cases a bulky organic substituent, which prevents disproportionation by steric shielding. The synthesis of these compounds succeeds by different methods such as the reduction of suitable organoelement(III) halides with alkali metals and magnesium or the treatment of element(I) halides with lithium organyls. They are deeply coloured, and their bonding situation may best be described by delocalized molecular orbitals. They show a singular chemical reactivity, which results in the formation of many secondary products possessing unprecedented structures and properties. The synthesis of organoelement subhalides still containing the elements in low oxidation states is discussed in more detail in the second part of this review. These compounds are easily accessible by the careful oxidation of the clusters with halogen donors such as hexachloroethane or with AlX3/X2 mixtures. They produce dimers via halogen bridges, but in certain cases monomers were observed even for the solid state. They are very effective starting compounds for secondary reactions and the generation of new products containing the elements in unusual oxidation states by salt-elimination reactions, for instance.

  3. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN...

  4. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN...

  5. 40 CFR 721.10391 - Copper gallium indium selenide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Copper gallium indium selenide. 721... Substances § 721.10391 Copper gallium indium selenide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as copper gallium indium selenide (PMN...

  6. Indium Phosphide Window Layers for Indium Gallium Arsenide Solar Cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.

    2005-01-01

    Window layers help in reducing the surface recombination at the emitter surface of the solar cells resulting in significant improvement in energy conversion efficiency. Indium gallium arsenide (In(x)Ga(1-x)As) and related materials based solar cells are quite promising for photovoltaic and thermophotovoltaic applications. The flexibility of the change in the bandgap energy and the growth of InGaAs on different substrates make this material very attractive for multi-bandgap energy, multi-junction solar cell approaches. The high efficiency and better radiation performance of the solar cell structures based on InGaAs make them suitable for space power applications. This work investigates the suitability of indium phosphide (InP) window layers for lattice-matched In(0.53)Ga(0.47)As (bandgap energy 0.74 eV) solar cells. We present the first data on the effects of the p-type InP window layer on p-on-n lattice-matched InGaAs solar cells. The modeled quantum efficiency results show a significant improvement in the blue region with the InP window. The bare InGaAs solar cell performance suffers due to high surface recombination velocity (10(exp 7) cm/s). The large band discontinuity at the InP/InGaAs heterojunction offers a great potential barrier to minority carriers. The calculated results demonstrate that the InP window layer effectively passivates the solar cell front surface, hence resulting in reduced surface recombination and therefore, significantly improving the performance of the InGaAs solar cell.

  7. Thermodynamic properties of uranium in gallium-aluminium based alloys

    NASA Astrophysics Data System (ADS)

    Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Chukin, A. V.; Smolenski, V. V.; Novoselova, A. V.; Osipenko, A. G.

    2015-10-01

    Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20 wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga-Al alloys containing 0.014-20 wt.% Al. Experiments were performed up to 1073 K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated.

  8. Formation of copper-indium-selenide and/or copper-indium-gallium-selenide films from indium selenide and copper selenide precursors

    DOEpatents

    Curtis, Calvin J.; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S.; Nekuda, Jennifer A.

    2011-11-15

    Liquid-based indium selenide and copper selenide precursors, including 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, are used to form crystalline copper-indium-selenide, and/or copper indium gallium selenide films (66) on substrates (52).

  9. Modeling of Copper Indium/Gallium Diselenide Superlattices

    NASA Astrophysics Data System (ADS)

    Scurlock, Steven

    2005-03-01

    The copper indium/gallium diselenide superlattice is investigated numerically for different layer lengths of this particular lattice matched crystal. The main emphasis is on applying the Kronig-Penny model for the relevant band gap energies. By varying the sizes of the layers, the region where superlattice behavior should exist is determined.

  10. Visible light electroluminescent diodes of indium-gallium phosphide

    NASA Technical Reports Server (NTRS)

    Clough, R.; Richman, D.; Tietjen, J.

    1970-01-01

    Vapor deposition and acceptor impurity diffusion techniques are used to prepare indium-gallium phosphide junctions. Certain problems in preparation are overcome by altering gas flow conditions and by increasing the concentration of phosphine in the gas. A general formula is given for the alloy's composition.

  11. Preparation Of Copper Indium Gallium Diselenide Films For Solar Cells

    DOEpatents

    Bhattacharya, Raghu N.; Contreras, Miguel A.; Keane, James; Tennant, Andrew L. , Tuttle, John R.; Ramanathan, Kannan; Noufi, Rommel

    1998-08-08

    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.

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

    DOEpatents

    Marks, Tobin J.; Chen, You-Xian

    2000-01-01

    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.

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

    SciTech Connect

    Not Available

    2011-06-01

    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.

  14. Formation of Flexible and Transparent Indium Gallium Zinc Oxide/Ag/Indium Gallium Zinc Oxide Multilayer Film

    NASA Astrophysics Data System (ADS)

    Kim, Jun Ho; Kim, Da-Som; Kim, Sun-Kyung; Yoo, Young-Zo; Lee, Jeong Hwan; Kim, Sang-Woo; Seong, Tae-Yeon

    2016-08-01

    In this study, the electrical, optical, and bending characteristics of amorphous indium gallium zinc oxide (IGZO)/Ag/IGZO (39 nm/19 nm/39 nm) multilayer films deposited on polyethylene terephthalate (PET) substrate at room temperature were investigated and compared with those of Sn-doped indium oxide (ITO) (100 nm thick) films. At 500 nm the ITO film transmitted 91.3% and the IGZO/Ag/IGZO multilayer film transmitted 88.8%. The calculated transmittance spectrum of the multilayer film was similar to the experimental result. The ITO film and IGZO/Ag/IGZO multilayer film, respectively, showed carrier concentrations of 1.79 × 1020 and 7.68 × 1021 cm-3 and mobilities of 27.18 cm2/V s and 18.17 cm2/V s. The ITO film had a sheet resistance of 134.9 Ω/sq and the IGZO/Ag/IGZO multilayer film one of 5.09 Ω/sq. Haacke's figure of merit (FOM) was calculated to be 1.94 × 10-3 for the ITO film and 45.02 × 10-3 Ω-1 for the IGZO/Ag/IGZO multilayer film. The resistance change of 100 nm-thick ITO film was unstable even after five cycles, while that of the IGZO/Ag/IGZO film was constant up to 1000 cycles.

  15. Deep Subgap Feature in Amorphous Indium Gallium Zinc Oxide. Evidence Against Reduced Indium

    SciTech Connect

    Sallis, Shawn; Quackenbush, Nicholas F.; Williams, Deborah S.; Senger, Mikell; Woicik, Joseph C.; White, Bruce E.; Piper, Louis F.

    2015-01-14

    Amorphous indium gallium zinc oxide (a-IGZO) is the archetypal transparent amorphous oxide semiconductor. In spite of the gains made with a-IGZO over amorphous silicon in the last decade, the presence of deep subgap states in a-IGZO active layers facilitate instabilities in thin film transistor properties under negative bias illumination stress. Several candidates could contribute to the formation of states within the band gap. We present evidence against In+ lone pair active electrons as the origin of the deep subgap features. No In+ species are observed, only In0 nano-crystallites under certain oxygen deficient growth conditions. Our results further support under coordinated oxygen as the source of the deep subgap states.

  16. (Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

    DOEpatents

    Marks, Tobin J.; Chen, You-Xian

    2002-01-01

    The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

  17. (Polyfluoroaryl) fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

    DOEpatents

    Marks, Tobin J.; Chen, You-Xian

    2001-01-01

    The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interfere in the ethylene polymerization process, while affecting the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

  18. Thermodynamic properties of uranium in liquid gallium, indium and their alloys

    NASA Astrophysics Data System (ADS)

    Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Osipenko, A. G.

    2015-09-01

    Activity, activity coefficients and solubility of uranium was determined in gallium, indium and gallium-indium alloys containing 21.8 (eutectic), 40 and 70 wt.% In. Activity was measured at 573-1073 K employing the electromotive force method, and solubility between room temperature (or the alloy melting point) and 1073 K employing direct physical measurements. Activity coefficients were obtained from the difference of experimentally determined temperature dependencies of uranium activity and solubility. Intermetallic compounds formed in the respective alloys were characterized using X-ray diffraction. Partial and excess thermodynamic functions of uranium in the studied alloys were calculated. Liquidus lines in U-Ga and U-In phase diagrams from the side rich in gallium or indium are proposed.

  19. Preparation and properties of hydrogen-intercalated indium and gallium monoselenides

    SciTech Connect

    Koz'mik, I.D.; Kovalyuk, Z.D.; Grigorchak, I.I.; Bakhmatyuk, B.P.

    1987-10-01

    Indium and gallium monoselenides can be intercalated by hydrogen ions. Thermodynamic parameters have been calculated for the intercalation and the proton diffusion coefficient in the van der Waals' spaces has been determined. The effects of hydrogen intercalation on the resistance perpendicular to the layers in InSe and GaSe have been determined.

  20. Precursors for formation of copper selenide, indium selenide, copper indium diselenide, and/or copper indium gallium diselenide films

    DOEpatents

    Curtis, Calvin J; Miedaner, Alexander; Van Hest, Maikel; Ginley, David S

    2014-11-04

    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.

  1. Investigation of an Electrochemical Method for Separation of Copper, Indium, and Gallium from Pretreated CIGS Solar Cell Waste Materials

    PubMed Central

    Gustafsson, Anna M. K.; Björefors, Fredrik; Steenari, Britt-Marie; Ekberg, Christian

    2015-01-01

    Recycling of the semiconductor material copper indium gallium diselenide (CIGS) is important to ensure a future supply of indium and gallium, which are relatively rare and therefore expensive elements. As a continuation of our previous work, where we recycled high purity selenium from CIGS waste materials, we now show that copper and indium can be recycled by electrodeposition from hydrochloric acid solutions of dissolved selenium-depleted material. Suitable potentials for the reduction of copper and indium were determined to be −0.5 V and −0.9 V (versus the Ag/AgCl reference electrode), respectively, using cyclic voltammetry. Electrodeposition of first copper and then indium from a solution containing the dissolved residue from the selenium separation and ammonium chloride in 1 M HCl gave a copper yield of 100.1 ± 0.5% and an indium yield of 98.1 ± 2.5%. The separated copper and indium fractions contained no significant contamination of the other elements. Gallium remained in solution together with a small amount of indium after the separation of copper and indium and has to be recovered by an alternative method since electrowinning from the chloride-rich acid solution was not effective. PMID:26347901

  2. Investigation of an Electrochemical Method for Separation of Copper, Indium, and Gallium from Pretreated CIGS Solar Cell Waste Materials.

    PubMed

    Gustafsson, Anna M K; Björefors, Fredrik; Steenari, Britt-Marie; Ekberg, Christian

    2015-01-01

    Recycling of the semiconductor material copper indium gallium diselenide (CIGS) is important to ensure a future supply of indium and gallium, which are relatively rare and therefore expensive elements. As a continuation of our previous work, where we recycled high purity selenium from CIGS waste materials, we now show that copper and indium can be recycled by electrodeposition from hydrochloric acid solutions of dissolved selenium-depleted material. Suitable potentials for the reduction of copper and indium were determined to be -0.5 V and -0.9 V (versus the Ag/AgCl reference electrode), respectively, using cyclic voltammetry. Electrodeposition of first copper and then indium from a solution containing the dissolved residue from the selenium separation and ammonium chloride in 1 M HCl gave a copper yield of 100.1 ± 0.5% and an indium yield of 98.1 ± 2.5%. The separated copper and indium fractions contained no significant contamination of the other elements. Gallium remained in solution together with a small amount of indium after the separation of copper and indium and has to be recovered by an alternative method since electrowinning from the chloride-rich acid solution was not effective. PMID:26347901

  3. (Polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of enhanced utility, uses thereof, and products based thereon

    DOEpatents

    Marks, Tobin J.; Chen, You-Xian

    2001-01-01

    The (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium are novel weakly coordinating anions which are are highly fluorinated. (Polyfluoroaryl)fluoroanions of one such type contain at least one ring substituent other than fluorine. These (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium have greater solubility in organic solvents, or have a coordinative ability essentially equal to or less than that of the corresponding (polyfluoroaryl)fluoroanion of aluminum, gallium, or indium in which the substituent is replaced by fluorine. Another type of new (polyfluoroaryl)fluoroanion of aluminum, gallium, and indium have 1-3 perfluorinated fused ring groups and 2-0 perfluorophenyl groups. When used as a cocatalyst in the formation of novel catalytic complexes with d- or f-block metal compounds having at least one leaving group such as a methyl group, these anions, because of their weak coordination to the metal center, do not interefere in the ethylene polymerization process, while affecting the the propylene process favorably, if highly isotactic polypropylene is desired. Thus, the (polyfluoroaryl)fluoroanions of aluminum, gallium, and indium of this invention are useful in various polymerization processes such as are described.

  4. Paired-pulse facilitation achieved in protonic/electronic hybrid indium gallium zinc oxide synaptic transistors

    SciTech Connect

    Guo, Li Qiang Ding, Jian Ning; Huang, Yu Kai; Zhu, Li Qiang

    2015-08-15

    Neuromorphic devices with paired pulse facilitation emulating that of biological synapses are the key to develop artificial neural networks. Here, phosphorus-doped nanogranular SiO{sub 2} electrolyte is used as gate dielectric for protonic/electronic hybrid indium gallium zinc oxide (IGZO) synaptic transistor. In such synaptic transistors, protons within the SiO{sub 2} electrolyte are deemed as neurotransmitters of biological synapses. Paired-pulse facilitation (PPF) behaviors for the analogous information were mimicked. The temperature dependent PPF behaviors were also investigated systematically. The results indicate that the protonic/electronic hybrid IGZO synaptic transistors would be promising candidates for inorganic synapses in artificial neural network applications.

  5. Controlled VLS Growth of Indium, Gallium and Tin Oxide Nanowiresvia Chemical Vapor Transport

    SciTech Connect

    Johnson, M.C.; Aloni, S.; McCready, D.E.; Bourret-Courchesne, E.D.

    2006-03-13

    We utilized a vapor-liquid-solid growth technique to synthesize indium oxide, gallium oxide, and tin oxide nanowires using chemical vapor transport with gold nanoparticles as the catalyst. Using identical growth parameters we were able to synthesize single crystal nanowires typically 40-100 nm diameter and more than 10-100 microns long. The products were characterized by means of XRD, SEM and HRTEM. All the wires were grown under the same growth conditions with growth rates inversely proportional to the source metal vapor pressure. Initial experiments show that different transparent oxide nanowires can be grown simultaneously on a single substrate with potential application for multi-component gas sensors.

  6. Controlled vapor-liquid-solid growth of indium, gallium, and tinoxide nanowires via chemical vapor transport

    SciTech Connect

    Johnson, M.C.; Aloni, S.; McCready, D.E.; Bourret-Courchesne, E.D.

    2006-03-31

    We utilized a vapor-liquid-solid growth technique tosynthesize indium oxide, gallium oxide, and tin oxide nanowires usingchemical vapor transport with gold nanoparticles as the catalyst. Usingidentical growth parameters, we were able to synthesize single crystalnanowires typically 40-100 nm diameter and more than 10-100 m long. Theproducts were characterized by means of X-ray diffraction (XRD), scanningelectron microscopy (SEM), and high-resolution transmission electronmicroscopy (HRTEM). All the wires were grown under the same growthconditions with growth rates inversely proportional to the source metalvapor pressure. Initial experiments show that different transparent oxidenanowires can be grown simultaneously on a single substrate withpotential application for multicomponent gas sensors.

  7. Paired-pulse facilitation achieved in protonic/electronic hybrid indium gallium zinc oxide synaptic transistors

    NASA Astrophysics Data System (ADS)

    Guo, Li Qiang; Zhu, Li Qiang; Ding, Jian Ning; Huang, Yu Kai

    2015-08-01

    Neuromorphic devices with paired pulse facilitation emulating that of biological synapses are the key to develop artificial neural networks. Here, phosphorus-doped nanogranular SiO2 electrolyte is used as gate dielectric for protonic/electronic hybrid indium gallium zinc oxide (IGZO) synaptic transistor. In such synaptic transistors, protons within the SiO2 electrolyte are deemed as neurotransmitters of biological synapses. Paired-pulse facilitation (PPF) behaviors for the analogous information were mimicked. The temperature dependent PPF behaviors were also investigated systematically. The results indicate that the protonic/electronic hybrid IGZO synaptic transistors would be promising candidates for inorganic synapses in artificial neural network applications.

  8. Frequency-Switchable Metamaterial Absorber Injecting Eutectic Gallium-Indium (EGaIn) Liquid Metal Alloy

    PubMed Central

    Ling, Kenyu; Kim, Hyung Ki; Yoo, Minyeong; Lim, Sungjoon

    2015-01-01

    In this study, we demonstrated a new class of frequency-switchable metamaterial absorber in the X-band. Eutectic gallium-indium (EGaIn), a liquid metal alloy, was injected in a microfluidic channel engraved on polymethyl methacrylate (PMMA) to achieve frequency switching. Numerical simulation and experimental results are presented for two cases: when the microfluidic channels are empty, and when they are filled with liquid metal. To evaluate the performance of the fabricated absorber prototype, it is tested with a rectangular waveguide. The resonant frequency was successfully switched from 10.96 GHz to 10.61 GHz after injecting liquid metal while maintaining absorptivity higher than 98%. PMID:26561815

  9. Separation and recovery of gallium and indium from simulated zinc refinery residue by liquid-liquid extraction

    SciTech Connect

    Nishihama, Syouhei; Hirai, Takayuki; Komasawa, Isao

    1999-03-01

    The separation and recovery of gallium and indium from zinc refinery residue, using liquid-liquid extraction, has been investigated. The major components with the exception of zinc can be removed by extraction with tri-n-butyl phosphate at low aqueous acidity, and gallium and indium can be separated from the remaining major component, zinc, by extraction with bis(2-ethylhexyl)phosphoric acid (D2EHPA) using the correct conditions, at which effective separation may be feasible. Extraction equilibrium formulations for the ternary system containing gallium, indium, and zinc have been established up to high conversion conditions of the extractant to metal complexes, when D2EHPA is employed as the extractant and kerosene as the diluent. The scrubbing behavior for the process can also be expressed by the proposed extraction scheme. Simulation work based on the equilibrium studies shows that indium may be recovered effectively from the mixture of gallium and zinc with 98.9% overall fractional recovery and 100% purity when using 5.0 {times} 10{sup {minus}2} mol/L D2EHPA. Gallium may then be recovered from zinc with 87.9% overall fractional recovery and 99.1% purity using 1.0 {times} 10{sup {minus}2} mol/L D2EHPA.

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

    NASA Astrophysics Data System (ADS)

    Yang, Jyun-Bao; Chang, Ting-Chang; Huang, Jheng-Jie; Chen, Yu-Chun; Chen, Yu-Ting; Tseng, Hsueh-Chih; Chu, Ann-Kuo; Sze, Simon M.

    2014-04-01

    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.

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

    SciTech Connect

    Yang, Jyun-Bao; Chen, Yu-Ting; Chu, Ann-Kuo; Chang, Ting-Chang; Huang, Jheng-Jie; Chen, Yu-Chun; Tseng, Hsueh-Chih; Sze, Simon M.

    2014-04-14

    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.

  12. ANALYSIS OF THE WATER-SPLITTING CAPABILITIES OF GALLIUM INDIUM PHOSPHIDE NITRIDE (GaInPN)

    SciTech Connect

    Head, J.; Turner, J.

    2007-01-01

    With increasing demand for oil, the fossil fuels used to power society’s vehicles and homes are becoming harder to obtain, creating pollution problems and posing hazard’s to people’s health. Hydrogen, a clean and effi cient energy carrier, is one alternative to fossil fuels. Certain semiconductors are able to harness the energy of solar photons and direct it into water electrolysis in a process known as photoelectrochemical water-splitting. P-type gallium indium phosphide (p-GaInP2) in tandem with GaAs is a semiconductor system that exhibits water-splitting capabilities with a solar-tohydrogen effi ciency of 12.4%. Although this material is effi cient at producing hydrogen through photoelectrolysis it has been shown to be unstable in solution. By introducing nitrogen into this material, there is great potential for enhanced stability. In this study, gallium indium phosphide nitride Ga1-yInyP1-xNx samples were grown using metal-organic chemical vapor deposition in an atmospheric-pressure vertical reactor. Photocurrent spectroscopy determined these materials to have a direct band gap around 2.0eV. Mott-Schottky analysis indicated p-type behavior with variation in fl atband potentials with varied frequencies and pH’s of solutions. Photocurrent onset and illuminated open circuit potential measurements correlated to fl atband potentials determined from previous studies. Durability analysis suggested improved stability over the GaInP2 system.

  13. Low valent and hydride complexes of NHC coordinated gallium and indium.

    PubMed

    Ball, Graham E; Cole, Marcus L; McKay, Alasdair I

    2012-01-21

    The reactions of the N-heterocyclic carbene 1,3-dimesitylimidazol-2-ylidene (IMes) with Ga[GaCl(4)], "GaI", InCl(2) and GaBr(3) have been examined. All reactions using a low valent gallium or indium starting material led to species of the form [{MX(2)(IMes)}(2)], where M = Ga, X = Cl (1), I (2); M = In, X = Cl (3), with disproportionation and loss of gallium metal in the case of 2. Reaction of IMes with gallium tribromide yields the air and moisture stable complex [GaBr(3)(IMes)] (4), which has been used as a precursor to the mixed bromohydrides [GaBrH(2)(IMes)] (5) and [GaBr(2)H(IMes)] (6) by (i) ligand redistribution with [GaH(3)(IMes)], (ii) hydride-bromide exchange with triethylsilane, and (iii) alkylation with (n)butyllithium followed by β-hydride elimination (6 only). Attempts to prepare 1, or monovalent analogues such as [{GaCl(IMes)}(n)], by thermally induced reductive elimination of dihydrogen from the chlorohydride congeners of 5 and 6 resulted in isolation of the known compounds [IMesCl][Cl] (IMesCl = 1,3-dimesityl-2-chloroimidazolium), and/or 1,3-dimesityl-2-dihydroimidazole, and gallium metal. Preliminary photochemical NMR spectroscopy and catalytic studies of 5 and 6 aimed at reductive dehydrogenation under milder conditions are reported. Compounds 1 and 4 have been characterised by single crystal X-ray structure determination. PMID:22080333

  14. The comparison between gallium arsenide and indium gallium arsenide as materials for solar cell performance using Silvaco application

    SciTech Connect

    Zahari, Suhaila Mohd; Norizan, Mohd Natashah; Mohamad, Ili Salwani; Osman, Rozana Aina Maulat; Taking, Sanna

    2015-05-15

    The work presented in this paper is about the development of single and multilayer solar cells using GaAs and InGaAs in AM1.5 condition. The study includes the modeling structure and simulation of the device using Silvaco applications. The performance in term of efficiency of Indium Gallium Arsenide (InGaAs) and GaAs material was studied by modification of the doping concentration and thickness of material in solar cells. The efficiency of the GaAs solar cell was higher than InGaAs solar cell for single layer solar cell. Single layer GaAs achieved an efficiency about 25% compared to InGaAs which is only 2.65% of efficiency. For multilayer which includes both GaAs and InGaAs, the output power, P{sub max} was 8.91nW/cm² with the efficiency only 8.51%. GaAs is one of the best materials to be used in solar cell as a based compared to InGaAs.

  15. Ohmic contact formation process on low n-type gallium arsenide (GaAs) using indium gallium zinc oxide (IGZO)

    SciTech Connect

    Yang, Seong-Uk; Jung, Woo-Shik; Lee, In-Yeal; Jung, Hyun-Wook; Kim, Gil-Ho; Park, Jin-Hong

    2014-02-01

    Highlights: • We propose a method to fabricate non-gold Ohmic contact on low n-type GaAs with IGZO. • 0.15 A/cm{sup 2} on-current and 1.5 on/off-current ratio are achieved in the junction. • InAs and InGaAs formed by this process decrease an electron barrier height. • Traps generated by diffused O atoms also induce a trap-assisted tunneling phenomenon. - Abstract: Here, an excellent non-gold Ohmic contact on low n-type GaAs is demonstrated by using indium gallium zinc oxide and investigating through time of flight-secondary ion mass spectrometry, X-ray photoelectron spectroscopy, transmission electron microscopy, J–V measurement, and H [enthalpy], S [entropy], Cp [heat capacity] chemistry simulation. In is diffused through GaAs during annealing and reacts with As, forming InAs and InGaAs phases with lower energy bandgap. As a result, it decreases the electron barrier height, eventually increasing the reverse current. In addition, traps generated by diffused O atoms induce a trap-assisted tunneling phenomenon, increasing generation current and subsequently the reverse current. Therefore, an excellent Ohmic contact with 0.15 A/cm{sup 2} on-current density and 1.5 on/off-current ratio is achieved on n-type GaAs.

  16. Isolated cationic crown ether complexes of gallium(I) and indium(I).

    PubMed

    Higelin, Alexander; Haber, Christoph; Meier, Stefan; Krossing, Ingo

    2012-10-21

    The recently reported homologous low-valent indium and gallium salts M(+)[Al(OR(F))(4)](-) (M = Ga, In; R(F) = C(CF(3))(3)) were used to extend the coordination chemistry of Ga(I) and In(I) to the isolated [18]crown-6 complexes [M([18]crown-6)(PhF)(2)](+)[Al(OR(F))(4)](-) in fluorobenzene solution (PhF = C(6)H(5)F). In contrast to known ion-paired compounds for M = In, our complexes are undisturbed and in the solid state free of contacts to the anion. A peculiar combination of very weak η(1)- and η(6)-coordination to the PhF-solvent was observed that allows speculation about the presence of a stereochemically active lone pair at M(I). Structure and energetics of these novel salts were rationalized on the basis of DFT calculations.

  17. Study of breakdown voltage of indium-gallium-zinc-oxide-based Schottky diode

    SciTech Connect

    Xin, Qian; Yan, Linlong; Luo, Yi; Song, Aimin

    2015-03-16

    In contrast to the intensive studies on thin-film transistors based on indium gallium zinc oxide (IGZO), the research on IGZO-based diodes is still very limited, particularly on their behavior and stability under high bias voltages. Our experiments reveal a sensitive dependence of the breakdown voltage of IGZO Schottky diodes on the anode metal and the IGZO film thickness. Devices with an Au anode are found to breakdown easily at a reverse bias as low as −2.5 V, while the devices with a Pd anode and a 200-nm, fully depleted IGZO layer have survived up to −15 V. All diodes are fabricated by radio-frequency magnetron sputtering at room temperature without any thermal treatment, yet showing an ideality factor as low as 1.14, showing the possibility of achieving high-performance Schottky diodes on flexible plastic substrate.

  18. Bowtie nanoantenna integrated with indium gallium arsenide antimonide for uncooled infrared detector with enhanced sensitivity.

    PubMed

    Choi, Sangjo; Sarabandi, Kamal

    2013-12-10

    A novel high-impedance nanoantenna with an embedded matching network is implemented to realize a highly sensitive infrared detector. A bowtie antenna is operated at its antiparallel resonance and loaded with a small low-bandgap (E(g)=0.52  eV) indium gallium arsenide antimonide (InGaAsSb) p-n junction. The structure is optimized for maximum power transfer and significant field enhancement at its terminals for a desired frequency band where the maximum quantum efficiency of InGaAsSb is observed. The sensitivity improvement of the proposed detector is evaluated against the traditional bulk detector and it is shown that the detectivity is improved by the field enhancement factor, which is approximately 20 for the case considered here.

  19. In situ analyses on negative ions in the indium-gallium-zinc oxide sputtering process

    SciTech Connect

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo

    2013-07-01

    The origin of negative ions in the dc magnetron sputtering process using a ceramic indium-gallium-zinc oxide target has been investigated by in situ analyses. The observed negative ions are mainly O{sup -} with energies corresponding to the target voltage, which originates from the target and barely from the reactive gas (O{sub 2}). Dissociation of ZnO{sup -}, GaO{sup -}, ZnO{sub 2}{sup -}, and GaO{sub 2}{sup -} radicals also contributes to the total negative ion flux. Furthermore, we find that some sputtering parameters, such as the type of sputtering gas (Ar or Kr), sputtering power, total gas pressure, and magnetic field strength at the target surface, can be used to control the energy distribution of the O{sup -} ion flux.

  20. Interface location-controlled indium gallium zinc oxide thin-film transistors using a solution process

    NASA Astrophysics Data System (ADS)

    Na, Jae Won; Kim, Yeong-gyu; Jung, Tae Soo; Tak, Young Jun; Park, Sung Pyo; Park, Jeong Woo; Kim, Si Joon; Kim, Hyun Jae

    2016-03-01

    The role of an interface as an electron-trapping layer in double-stacked indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) was investigated and interface location-controlled (ILC) IGZO TFTs were introduced. In the ILC TFTs, the thickness of the top and bottom IGZO layers is controlled to change the location of the interface layer. The system exhibited improved electrical characteristics as the location of the interface layer moved further from the gate insulator: field-effect mobility increased from 0.36 to 2.17 cm2 V-1 s-1, and the on-current increased from 2.43  ×  10-5 to 1.33  ×  10-4 A. The enhanced electrical characteristics are attributed to the absence of an electron-trapping interface layer in the effective channel layer where electrons are accumulated under positive gate bias voltage.

  1. Electrical effect of titanium diffusion on amorphous indium gallium zinc oxide

    SciTech Connect

    Choi, Seung-Ha; Jung, Woo-Shik; Park, Jin-Hong

    2012-11-19

    In this work, thermal diffusion phenomenon of Ti into amorphous indium gallium zinc oxide ({alpha}-IGZO) was carefully investigated with secondary ion mass spectroscopy, I-V, and R{sub s} measurement systems and HSC chemistry simulation tool. According to the experimental and simulated results, the diffused Ti atoms were easily oxidized due to its lowest oxidation free energy. Since oxygen atoms were decomposed from the {alpha}-IGZO during the oxidation of Ti, the number of oxygen vacancies working as electron-donating sites in {alpha}-IGZO was dramatically increased, contributing to the decrease of resistivity ({rho}) from 1.96 {Omega} cm (as-deposited {alpha}-IGZO) to 1.33 Multiplication-Sign 10{sup -3}{Omega} cm (350 Degree-Sign C annealed {alpha}-IGZO).

  2. Thermal Conductivity of Amorphous Indium-Gallium-Zinc Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Toru; Yagi, Takashi; Oka, Nobuto; Jia, Junjun; Yamashita, Yuichiro; Hattori, Koichiro; Seino, Yutaka; Taketoshi, Naoyuki; Baba, Tetsuya; Shigesato, Yuzo

    2013-02-01

    We investigated the thermal conductivity of 200-nm-thick amorphous indium-gallium-zinc-oxide (a-IGZO) films. Films with a chemical composition of In:Ga:Zn= 1:1:0.6 were prepared by dc magnetron sputtering using an IGZO ceramic target and an Ar-O2 sputtering gas. The carrier density of the films was systematically controlled from 1014 to >1019 cm-3 by varying the O2 flow ratio. Their Hall mobility was slightly higher than 10 cm2·V-1·s-1. Those films were sandwiched between 100-nm-thick Mo layers; their thermal diffusivity, measured by a pulsed light heating thermoreflectance technique, was ˜5.4×10-7 m2·s-1 and was almost independent of the carrier density. The average thermal conductivity was 1.4 W·m-1·K-1.

  3. Molybdenum Disulfide as a Protection Layer and Catalyst for Gallium Indium Phosphide Solar Water Splitting Photocathodes.

    PubMed

    Britto, Reuben J; Benck, Jesse D; Young, James L; Hahn, Christopher; Deutsch, Todd G; Jaramillo, Thomas F

    2016-06-01

    Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis because MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, and light-limited current density) after 60 h of operation. This represents a 500-fold increase in stability compared to bare p-GaInP2 samples tested in identical conditions. PMID:27196435

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

    SciTech Connect

    Sallis, S.; Williams, D. S.; Butler, K. T.; Walsh, A.; Quackenbush, N. F.; Junda, M.; Podraza, N. J.; Fischer, D. A.; Woicik, J. C.; White, B. E.; Piper, L. F. J.

    2014-06-09

    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.

  5. Water-soluble thin film transistors and circuits based on amorphous indium-gallium-zinc oxide.

    PubMed

    Jin, Sung Hun; Kang, Seung-Kyun; Cho, In-Tak; Han, Sang Youn; Chung, Ha Uk; Lee, Dong Joon; Shin, Jongmin; Baek, Geun Woo; Kim, Tae-il; Lee, Jong-Ho; Rogers, John A

    2015-04-22

    This paper presents device designs, circuit demonstrations, and dissolution kinetics for amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) comprised completely of water-soluble materials, including SiNx, SiOx, molybdenum, and poly(vinyl alcohol) (PVA). Collections of these types of physically transient a-IGZO TFTs and 5-stage ring oscillators (ROs), constructed with them, show field effect mobilities (∼10 cm2/Vs), on/off ratios (∼2×10(6)), subthreshold slopes (∼220 mV/dec), Ohmic contact properties, and oscillation frequency of 5.67 kHz at supply voltages of 19 V, all comparable to otherwise similar devices constructed in conventional ways with standard, nontransient materials. Studies of dissolution kinetics for a-IGZO films in deionized water, bovine serum, and phosphate buffer saline solution provide data of relevance for the potential use of these materials and this technology in temporary biomedical implants.

  6. Commercial and industrial applications of indium gallium arsenide near-infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Cohen, Marshall J.; Ettenberg, Martin H.; Lange, Michael J.; Olsen, Gregory H.

    1999-07-01

    Sensors Unlimited, Inc. has developed focal pane arrays (FPAs) fabricated with indium gallium arsenide (InGaAs) photodiode arrays and silicon CMOS readout integrated circuits. These devices are readily available in a wide variety of formats suitable for commercial and industrial applications. InGaAs FPAs are sensitive to the near IR, operate without cooling, and come in both 2D formats and 1D formats. 1D InGaAs FPAs are used as both spectroscopic detectors and line scan imagers. Key applications include miniature spectrometers used for wavelength control and monitoring of WDM laser sources, octane determination, the sorting o plastics during recycling, and web process control. 2D InGaAs FPAs find use in applications such as laser beam profiling, visualization of 'clear' ice on aircraft and roadways, and industrial thermal imaging.

  7. Molybdenum Disulfide as a Protection Layer and Catalyst for Gallium Indium Phosphide Solar Water Splitting Photocathodes.

    PubMed

    Britto, Reuben J; Benck, Jesse D; Young, James L; Hahn, Christopher; Deutsch, Todd G; Jaramillo, Thomas F

    2016-06-01

    Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis because MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, and light-limited current density) after 60 h of operation. This represents a 500-fold increase in stability compared to bare p-GaInP2 samples tested in identical conditions.

  8. Microencapsulation of gallium-indium (Ga-In) liquid metal for self-healing applications.

    PubMed

    Blaiszik, B J; Jones, A R; Sottos, N R; White, S R

    2014-01-01

    Microcapsules containing a liquid metal alloy core of gallium-indium (Ga-In) are prepared via in situ urea-formaldehyde (UF) microencapsulation. The capsule size, shape, thermal properties, and shell wall thickness are investigated. We prepare ellipsoidal capsules with major and minor diameter aspect ratios ranging from 1.64 to 1.08 and with major diameters ranging from 245 µm to 3 µm. We observe that as the capsule major diameter decreases, the aspect ratio approaches 1. The thermal properties of the prepared microcapsules are investigated by thermogravimetric (TGA) and differential scanning calorimetry (DSC). Microcapsules are shown to survive incorporation into an epoxy matrix and to trigger via mechanical damage to the cured matrix. Microcapsules containing liquid metal cores may have diverse applications ranging from self-healing to contrast enhancement or the demonstration of mechano-adaptive circuitry.

  9. Effect of strain on indium incorporation in heteroepitaxial (indium, gallium) nitride nanomaterials

    NASA Astrophysics Data System (ADS)

    Ewoldt, David A.

    2011-12-01

    One of the challenges facing LED lighting today is the achievement of low-cost true white lighting. Ideally, multiple LEDs of different colors, blue, red and green, would be utilized in order to achieve white light. Currently, the quality of green LEDs is low when compared to the red and blue counterparts. Green emission from LEDs is difficult to achieve due to phase segregation that occurs during growth of the (In,Ga)N LED structure, which separates into compositions of high and low InN concentration and prevents the moderate composition required for green emission. On the nanoscale, strain effects in the (In,Ga)N material system give rise to shifts in optical properties. Relieving strain allows for the incorporation of additional indium nitride, which shifts the wavelength of light emitted by the structure. In order to control strain effects, growth templates were fabricated by several methods (PAA, FIB, EBL). A robust process for fabrication of pores down to 25 nm in diameter has been developed in order to investigate this effect. From this process, a template using e-beam lithography has been created and then growth of (In,Ga)N on this template in a metallorganic chemical vapor deposition system was performed. As (In,Ga)N grows from the GaN substrate, it is naturally strained due to the lattice mismatch. Lateral growth out of the templates relieves strain by allowing the rods to expand as they grow out of the prepared pores. The effect of the diameter of pores on the emission characteristics has been analyzed and a strong logarithmic trend was discovered correlating emission wavelength to pore diameter. In addition to allowing control over the wavelength of emission based on pore diameter, the process that has been developed and demonstrated will allow a distribution of pore sizes that could facilitate color mixing.

  10. Growth of gallium nitride and indium nitride nanowires on conductive and flexible carbon cloth substrates

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Ling, Yichuan; Wang, Gongming; Lu, Xihong; Tong, Yexiang; Li, Yat

    2013-02-01

    We report a general strategy for synthesis of gallium nitride (GaN) and indium nitride (InN) nanowires on conductive and flexible carbon cloth substrates. GaN and InN nanowires were prepared via a nanocluster-mediated growth method using a home built chemical vapor deposition (CVD) system with Ga and In metals as group III precursors and ammonia as a group V precursor. Electron microscopy studies reveal that the group III-nitride nanowires are single crystalline wurtzite structures. The morphology, density and growth mechanism of these nanowires are determined by the growth temperature. Importantly, a photoelectrode fabricated by contacting the GaN nanowires through a carbon cloth substrate shows pronounced photoactivity for photoelectrochemical water oxidation. The ability to synthesize group III-nitride nanowires on conductive and flexible substrates should open up new opportunities for nanoscale photonic, electronic and electrochemical devices.We report a general strategy for synthesis of gallium nitride (GaN) and indium nitride (InN) nanowires on conductive and flexible carbon cloth substrates. GaN and InN nanowires were prepared via a nanocluster-mediated growth method using a home built chemical vapor deposition (CVD) system with Ga and In metals as group III precursors and ammonia as a group V precursor. Electron microscopy studies reveal that the group III-nitride nanowires are single crystalline wurtzite structures. The morphology, density and growth mechanism of these nanowires are determined by the growth temperature. Importantly, a photoelectrode fabricated by contacting the GaN nanowires through a carbon cloth substrate shows pronounced photoactivity for photoelectrochemical water oxidation. The ability to synthesize group III-nitride nanowires on conductive and flexible substrates should open up new opportunities for nanoscale photonic, electronic and electrochemical devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr

  11. Synthesis and characterization of dual function vanadyl, gallium and indium curcumin complexes for medicinal applications.

    PubMed

    Mohammadi, Khosro; Thompson, Katherine H; Patrick, Brian O; Storr, Tim; Martins, Candice; Polishchuk, Elena; Yuen, Violet G; McNeill, John H; Orvig, Chris

    2005-11-01

    Novel bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione (curcumin) complexes with the formula, ML(3), where M is Ga(III) or In(III), or of the formula, ML(2) where M is [VO](2+), have been synthesized and characterized by mass spectrometry, infrared and absorption spectroscopies, and elemental analysis. A new ligand, bis[4-acetyl-3-hydroxyphenyl]-1,6-heptadiene-3,5-dione (diacetylbisdemethoxycurcumin, DABC) was similarly characterized; an X-ray structure analysis was performed. Vanadyl complexes tested in an acute i.p. testing protocol in STZ-diabetic rats showed a lack of insulin enhancing potential. Vanadyl complexes were, however, more cytotoxic than were the ligands alone in standard MTT (3-[4,5-dimethylthiazole-2-yl]ate, -2,5-diphenyl-tetrazolium bromide) cytotoxicity testing, using mouse lymphoma cells. With the exception of DABC, that was not different from VO(DABC)(2), the complexes were not significantly different from one another, with IC(50) values in the 5-10 microM range. Gallium and indium curcumin complexes had IC(50) values in the same 5-10 microM range; whereas Ga(DAC)(3) and In(DAC)(3) (where DAC=diacetylcurcumin) were much less cytotoxic (IC(50)=20-30 microM). Antioxidant capacity was decreased in VO(DAC)(2), Ga(DAC)(3), and In(DAC)(3), compared to vanadyl, gallium and indium curcumin, corroborating the importance of curcumin's free phenolic OH groups for scavenging oxidants, and correlated with reduced cytotoxic potential. PMID:16171869

  12. Synthesis and characterization of electrodeposited copper indium selenide and copper (indium, gallium) selenide thin films

    NASA Astrophysics Data System (ADS)

    Friedfeld, Robert Bonheur

    while the Bragg peaks shift to larger diffraction angles with increasing gallium content in the film. This is evidence to support the successful formation of CIGS films. This data is further corroborated by the energy dispersive spectroscopy and Auger electron spectroscopy data.

  13. Effect of microtextured surface topography on the wetting behavior of eutectic gallium-indium alloys.

    PubMed

    Kramer, Rebecca K; Boley, J William; Stone, Howard A; Weaver, James C; Wood, Robert J

    2014-01-21

    Liquid-embedded elastomer electronics have recently attracted much attention as key elements of highly deformable and "soft" electromechanical systems. Many of these fluid-elastomer composites utilize liquid metal alloys because of their high conductivities and inherent compliance. Understanding how these alloys interface with surfaces of various composition and texture is critical to the development of parallel processing technology, which is needed to create more complex and low-cost systems. In this work, we explore the wetting behaviors between droplets of gallium-indium alloys and thin metal films, with an emphasis on tin and indium substrates. We find that metallic droplets reactively wet thin metal foils, but the wettability of the foils may be tuned by the surface texture (produced by sputtering). The effects of both composition and texture of the substrate on wetting dynamics are quantified by measuring contact angle and droplet contact diameter as a function of time. Finally, we apply the Cassie-Baxter model to the sputtered and native substrates to gain insight into the behavior of liquid metals and the role of the oxide formation during interfacial processes.

  14. Effect of microtextured surface topography on the wetting behavior of eutectic gallium-indium alloys.

    PubMed

    Kramer, Rebecca K; Boley, J William; Stone, Howard A; Weaver, James C; Wood, Robert J

    2014-01-21

    Liquid-embedded elastomer electronics have recently attracted much attention as key elements of highly deformable and "soft" electromechanical systems. Many of these fluid-elastomer composites utilize liquid metal alloys because of their high conductivities and inherent compliance. Understanding how these alloys interface with surfaces of various composition and texture is critical to the development of parallel processing technology, which is needed to create more complex and low-cost systems. In this work, we explore the wetting behaviors between droplets of gallium-indium alloys and thin metal films, with an emphasis on tin and indium substrates. We find that metallic droplets reactively wet thin metal foils, but the wettability of the foils may be tuned by the surface texture (produced by sputtering). The effects of both composition and texture of the substrate on wetting dynamics are quantified by measuring contact angle and droplet contact diameter as a function of time. Finally, we apply the Cassie-Baxter model to the sputtered and native substrates to gain insight into the behavior of liquid metals and the role of the oxide formation during interfacial processes. PMID:24358994

  15. Preparation of copper-indium-gallium-diselenide precursor films by electrodeposition for fabricating high efficiency solar cells

    DOEpatents

    Bhattacharya, Raghu N.; Hasoon, Falah S.; Wiesner, Holm; Keane, James; Noufi, Rommel; Ramanathan, Kannan

    1999-02-16

    A photovoltaic cell exhibiting an overall conversion efficiency of 13.6% is prepared from a copper-indium-gallium-diselenide precursor thin film. The film is fabricated by first simultaneously electrodepositing copper, indium, gallium, and selenium onto a glass/molybdenum substrate (12/14). The electrodeposition voltage is a high frequency AC voltage superimposed upon a DC voltage to improve the morphology and growth rate of the film. The electrodeposition is followed by physical vapor deposition to adjust the final stoichiometry of the thin film to approximately Cu(In.sub.1-n Ga.sub.x)Se.sub.2, with the ratio of Ga/(In+Ga) being approximately 0.39.

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

    SciTech Connect

    Assael, Marc J.; Armyra, Ivi J.; Brillo, Juergen; Stankus, Sergei V.; Wu Jiangtao; Wakeham, William A.

    2012-09-15

    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.

  17. Indium nitride and gallium nitride grown from the melt at subatmospheric pressures

    NASA Astrophysics Data System (ADS)

    Dyck, Jeffrey Scott

    The wide-band-gap, group III nitride semiconductors (Al,Ga,In)N are a promising system for visible/near-UV optoelectronic devices. Despite significant technological advances, improvement in material quality is required. Moreover, pure InN has received little attention due to unavailability of high quality crystals, and uncertainty on the fundamental properties of InN exist in the literature. In this work, bulk, polycrystalline gallium nitride and indium nitride were synthesized without a substrate by saturating gallium or indium metal with atomic nitrogen from both ECR and ball plasma microwave sources. The results show that atomic nitrogen is an attractive alternative to high pressure N2 for the synthesis of the bulk nitrides. The GaN and InN crystals were confirmed to be wurtzitic by x-ray and electron diffraction. Weak yellow-band photoluminescence intensity and near-band-edge linewidths of 4 meV for some GaN crystals indicated high optical quality. The high crystalline quality of the InN crystals allowed for the most precise measurement of the lattice parameters currently possible: a = 3.5366 A, c = 5.7009 A. Raman spectra of InN were taken from both randomly oriented polycrystals and groups of oriented, faceted platelets. Phonon modes were assigned as ETO1=445cm -1,ATO1 =472cm-1, E22=448 cm-1, and ALO1=558 cm-1 , and previous disagreement in the literature is explained. The E22 and ALO1 linewidths of were 2.5 and 19 cm-1 are the narrowest ever reported. The measured TO phonon frequencies and lattice parameters were compared to those calculated from first principles and excellent agreement was found. Preliminary experiments on the growth of GaN from Ga/In alloys were performed. Addition of inert, soluble third elements to the Ga/N melt depresses the liquidus temperature, which is equivalent to increasing the solubility of GaN at constant temperature. Upon introduction of an (0001) sapphire substrate into the melt, oriented thin films of the solid nitride formed

  18. Coherent near infrared photodetection with indium gallium arsenide based optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Fu, Jun-Xian

    Over the extremely broad electromagnetic spectrum, the near-infrared region (0.7--3 mum) is of great interests to physicists, chemists and biologists. Coherent photo-detection in the near-infrared as well as visible and other wavelength regions is extremely useful in identifying coherent light sources from the noisy background. It has great potential to be applied to single-molecule detection by surface-enhanced coherent anti-Stokes Raman scattering. Other applications include chemical gas detection, remote sensing and environmental monitoring, semiconductor processing control and others. Indium gallium arsenide (InGaAs) based optoelectronic devices have been extensively investigated in the wavelength range extending from 800nm for gallium-rich material to 3mum for indium-rich material. A range of InGaAs alloys with bandgap energies in the near infrared wavelength range are investigated by solid-source molecular beam epitaxy (SSMBE). They include strain-free standard In0.532Ga0.468As and In0.532Ga0.468 AsNxSby lattice-matched to InP substrates, highly strained pseudomorphic InxGa1-xAs/InyGa 1-yAs quantum structures on InP substrates and relaxed metamorphic thick Inx>0.8Ga1-xAs device layers with cyclic arsenic-assisted in-situ annealed step-graded InAlAs buffer layers on GaAs and InP substrates. An InP/InAlAs/InGaAs heterojunction bipolar phototransistor (HPT) is designed, simulated and fabricated. The electrical and optical properties, such as responsivity and spectral response, of the HPT are characterized. A compact standing-wave Fourier-transform interferometer system capable of coherent detection in the near-infrared region is demonstrated. A new technique of identifying coherent light sources using harmonic Fourier spectra analysis is developed. The system only includes a PZT-controlled gold-coated scan mirror and a partial-transparent (3.8% single-path loss) InP/InAlAs/InGaAs HPT. The close-loop scan range of PZT-controlled mirror is 32mum. With such mirror

  19. Indium gallium arsenide imaging with smaller cameras, higher-resolution arrays, and greater material sensitivity

    NASA Astrophysics Data System (ADS)

    Ettenberg, Martin H.; Cohen, Marshall J.; Brubaker, Robert M.; Lange, Michael J.; O'Grady, Matthew T.; Olsen, Gregory H.

    2002-08-01

    Indium Gallium Arsenide (InGaAs) photodiode arrays have numerous commercial, industrial, and military applications. During the past 10 years, great strides have been made in the development of these devices starting with simple 256-element linear photodiode arrays and progressing to the large 640 x 512 element area arrays now readily available. Linear arrays are offered with 512 elements on a 25 micron pitch with no defective pixels, and are used in spectroscopic monitors for wavelength division multiplexing (WDM) systems as well as in machine vision applications. A 320 x 240 solid-state array operates at room temperature, which allows development of a camera which is smaller than 25 cm3 in volume, weighs less than 100 g and uses less than 750 mW of power. Two dimensional focal plane arrays and cameras have been manufactured with detectivity, D*, greater than 1014 cm-(root)Hz/W at room temperature and have demonstrated the ability to image at night. Cameras are also critical tools for the assembly and performance monitoring of optical switches and add-drop multiplexers in the telecommunications industry. These same cameras are used for the inspection of silicon wafers and fine art, laser beam profiling, and metals manufacturing. By varying the Indium content, InGaAs photodiode arrays can be tailored to cover the entire short-wave infrared spectrum from 1.0 micron to 2.5 microns. InGaAs focal plane arrays and cameras sensitive to 2.0 micron wavelength light are now available in 320 x 240 formats.

  20. An Indium Gallium Arsenide Visible/SWIR Focal Plane Array for Low Light Level Imaging

    NASA Technical Reports Server (NTRS)

    Cohen, Marshall J.; Ettenberg, Martin H.; Lange, Michael J.; Olsen, Gregory H.

    1999-01-01

    PIN photodiodes fabricated from indium gallium arsenide lattice-matched to indium phosphide substrates (In(.53)Ga(.47)As/InP) exhibit low reverse saturation current densities (JD < 10(exp -8) A/sq cm), and high shunt resistance-area products (RoA > 10(exp 6) omega-sq cm) at T=290K. Backside-illuminated, hybrid-integrated InGaAs FPAs are sensitive from 0.9 micrometers to 1.7 micrometers. 290K detectivities, D(*), greater than 10(exp 14) cm-(square root of Hz/W) are demonstrated. This represents the highest room temperature detectivity of any infrared material. The long wavelength cutoff (1.7 micrometers) makes In(.53)Ga(.47)As an idea match to the available airglow that has major peaks at 1.3 micrometers and 1.6 micrometers. The short wavelength 'cut-on' at 0.9 micrometers is due to absorption in the InP substrate. We will report on new InGaAs FPA epitaxial structures and processing techniques. These have resulted in improved performance in the form of a 10 x increase in detectivity and visible response via removal of the InP substrate. The resulting device features visible and SWIR response with greater than 15% quantum efficiency at 0.5 micrometers while maintaining the long wavelength cutoff. Imaging has been demonstrated under overcast starlight/urban glow conditions with cooling provided by a single stage thermoelectric cooler. Details on the material structure and device fabrication, quantitative characterization of spectral response and detectivity, as well as examples of night vision imagery are presented.

  1. Electronic transitions in the bandgap of copper indium gallium diselenide polycrystalline thin films

    NASA Astrophysics Data System (ADS)

    Heath, Jennifer Theresa

    The electronic properties of polycrystalline copper indium gallium diselenide thin films have been investigated, with emphasis on understanding the distribution and origin of electronic states in the bandgap. The samples studied were working photovoltaic devices with the structure ZnO/CdS/CuIn1-xGa xSe2/Mo, and photovoltaic efficiencies ranging from 8 to 16%. The CdS layer and the p-type CuIn1-xGa xSe2 film create the n+- p junction at the heart of these devices. The samples were investigated using four techniques based on the electrical response of the junction: admittance spectroscopy, drive level capacitance profiling, transient photocapacitance spectroscopy, and transient photocurrent spectroscopy. From these measurements the free carrier densities, defect densities within the bandgap, spatial uniformity, and minority carrier mobilities have been deduced. The sub-bandgap response from the CuIn1-xGaxSe2 film was dominated by two defects. One exhibited a thermal transition to the valence band with an activation energy ranging between 0.1 and 0.3 eV and thermal emission prefactors obeying the Meyer-Neldel rule. The second was detected as an optical transition 0.8 eV from the valence band edge. Neither of these defects exhibited densities that varied systematically with gallium content, implying that they are not directly connected with the group III elements in these alloys. The defect densities also do not clearly correlate with the photovoltaic device performance; however, the position of the 0.8 eV defect lies nearer to mid-gap in the higher gallium, and hence higher band gap, material. This implies that it may be a more important recombination center in these devices and may be partially responsible for the reduced photovoltaic efficiencies observed when Ga/(In + Ga) > 0.4. An additional defect response was observed near mid-gap in films grown by processes known to produce lower quality devices. The influence of defects located at grain boundaries was also

  2. Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz.

    PubMed

    Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

    2015-01-01

    Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning. PMID:26138510

  3. Performance of Indium Gallium Zinc Oxide Thin-Film Transistors in Saline Solution

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Lacour, S. P.

    2016-06-01

    Transistors are often envisioned as alternative transducing devices to microelectrodes to communicate with the nervous system. Independently of the selected technology, the transistors should have reliable performance when exposed to physiological conditions (37°C, 5% CO2). Here, we report on the reliable performance of parylene encapsulated indium gallium zinc oxide (IGZO) based thin-film transistors (TFTs) after prolonged exposure to phosphate buffer saline solution in an incubator. The encapsulated IGZO TFTs (W/L = 500 μm/20 μm) have an ON/OFF current ratio of 107 and field effect mobility of 8.05 ± 0.78 cm2/Vs. The transistors operate within 4 V; their threshold voltages and subthreshold slope are ~1.9 V and 200 mV/decade, respectively. After weeks immersed in saline solution and at 37°C, we did not observe any significant deterioration in the transistors' performance. The long-term stability of IGZO transistors at physiological conditions is a promising result in the direction of metal oxide bioelectronics.

  4. Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting

    PubMed Central

    Kim, Hoon-sik; Brueckner, Eric; Song, Jizhou; Li, Yuhang; Kim, Seok; Lu, Chaofeng; Sulkin, Joshua; Choquette, Kent; Huang, Yonggang; Nuzzo, Ralph G.; Rogers, John A.

    2011-01-01

    Properties that can now be achieved with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements for existing infrastructure in general illumination, with important implications for efficient use of energy. Further advances in this technology will benefit from reexamination of the modes for incorporating this materials technology into lighting modules that manage light conversion, extraction, and distribution, in ways that minimize adverse thermal effects associated with operation, with packages that exploit the unique aspects of these light sources. We present here ideas in anisotropic etching, microscale device assembly/integration, and module configuration that address these challenges in unconventional ways. Various device demonstrations provide examples of the capabilities, including thin, flexible lighting “tapes” based on patterned phosphors and large collections of small light emitters on plastic substrates. Quantitative modeling and experimental evaluation of heat flow in such structures illustrates one particular, important aspect of their operation: small, distributed LEDs can be passively cooled simply by direct thermal transport through thin-film metallization used for electrical interconnect, providing an enhanced and scalable means to integrate these devices in modules for white light generation. PMID:21666096

  5. Impact of atmospheric species on copper indium gallium selenide solar cell stability: an overview

    NASA Astrophysics Data System (ADS)

    Theelen, Mirjam

    2016-01-01

    An overview of the measurement techniques and results of studies on the stability of copper indium gallium selenide (CIGS) solar cells and their individual layers in the presence of atmospheric species is presented: in these studies, Cu(In,Ga)Se2 solar cells, their molybdenum back contact, and their ZnO:Al front contact were exposed to liquid water purged with gases from the atmosphere, like carbon dioxide (CO2), oxygen (O2), nitrogen (N2), and air. The samples were analyzed before, during, and after exposure in order to define their stability under these conditions. The complete CIGS solar cells as well as the ZnO:Al front contact degraded rapidly when exposed to H2O combined with CO2, while they were relatively stable in H2O purged with O2 or N2. This was caused by either degradation of the grain boundaries in the ZnO:Al film or by the dissolution of part of this film. Uncovered molybdenum films, on the other hand, oxidized rapidly in the presence of H2O and O2, while they were more stable in the presence of H2O with N2 and/or CO2.

  6. Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

    NASA Astrophysics Data System (ADS)

    Bercegol, Adrien; Chacko, Binoy; Klenk, Reiner; Lauermann, Iver; Lux-Steiner, Martha Ch.; Liero, Matthias

    2016-04-01

    For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoretical outlook is made using three-dimensional simulations to investigate the effect of point-contact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality, and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95%, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

  7. Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

    2015-07-01

    Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.

  8. Amorphous indium-gallium-zinc-oxide as electron transport layer in organic photodetectors

    SciTech Connect

    Arora, H.; Malinowski, P. E. Chasin, A.; Cheyns, D.; Steudel, S.; Schols, S.; Heremans, P.

    2015-04-06

    Amorphous indium-gallium-zinc-oxide (a-IGZO) is demonstrated as an electron transport layer (ETL) in a high-performance organic photodetector (OPD). Dark current in the range of 10 nA/cm{sup 2} at a bias voltage of −2 V and a high photoresponse in the visible spectrum were obtained in inverted OPDs with poly(3-hexylthiophene) and phenyl-C{sub 61}-butyric acid methyl ester active layer. The best results were obtained for the optimum a-IGZO thickness of 7.5 nm with specific detectivity of 3 × 10{sup 12} Jones at the wavelength of 550 nm. The performance of the best OPD devices using a-IGZO was shown to be comparable to state-of-the-art devices based on TiO{sub x} as ETL, with higher rectification achieved in reverse bias. Yield and reproducibility were also enhanced with a-IGZO, facilitating fabrication of large area OPDs. Furthermore, easier integration with IGZO-based readout backplanes can be envisioned, where the channel material can be used as photodiode buffer layer after additional treatment.

  9. Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting.

    PubMed

    Kim, Hoon-sik; Brueckner, Eric; Song, Jizhou; Li, Yuhang; Kim, Seok; Lu, Chaofeng; Sulkin, Joshua; Choquette, Kent; Huang, Yonggang; Nuzzo, Ralph G; Rogers, John A

    2011-06-21

    Properties that can now be achieved with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements for existing infrastructure in general illumination, with important implications for efficient use of energy. Further advances in this technology will benefit from reexamination of the modes for incorporating this materials technology into lighting modules that manage light conversion, extraction, and distribution, in ways that minimize adverse thermal effects associated with operation, with packages that exploit the unique aspects of these light sources. We present here ideas in anisotropic etching, microscale device assembly/integration, and module configuration that address these challenges in unconventional ways. Various device demonstrations provide examples of the capabilities, including thin, flexible lighting "tapes" based on patterned phosphors and large collections of small light emitters on plastic substrates. Quantitative modeling and experimental evaluation of heat flow in such structures illustrates one particular, important aspect of their operation: small, distributed LEDs can be passively cooled simply by direct thermal transport through thin-film metallization used for electrical interconnect, providing an enhanced and scalable means to integrate these devices in modules for white light generation.

  10. Forward-biased current annealing of radiation degraded indium phosphide and gallium arsenide solar cells

    NASA Technical Reports Server (NTRS)

    Michael, Sherif; Cypranowski, Corinne; Anspaugh, Bruce

    1990-01-01

    The preliminary results of a novel approach to low-temperature annealing of previously irradiated indium phosphide and gallium arsenide solar cells are reported. The technique is based on forward-biased current annealing. The two types of III-V solar cells were irradiated with 1-MeV electrons to a fluence level of (1-10) x 10 to the 14th electrons/sq cm. Several annealing attempts were made, varying all conditions. Optimum annealing was achieved when cells were injected with minority currents at a constant 90 C. The current density for each type of cell was also determined. Significant recovery of degraded parameters was achieved in both cases. However, the InP cell recovery notably exceeded the recovery in GaAs cells. The recovery is thought to be caused by current-stimulated reordering of the radiator-induced displacement damage. Both types of cell were then subjected to several cycles of irradiation and annealing. The results were also very promising. The significant recovery of degraded cell parameters at low temperature might play a major role in considerably extending the end of life of future spacecraft.

  11. Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz.

    PubMed

    Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

    2015-01-01

    Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.

  12. Water-soluble thin film transistors and circuits based on amorphous indium-gallium-zinc oxide.

    PubMed

    Jin, Sung Hun; Kang, Seung-Kyun; Cho, In-Tak; Han, Sang Youn; Chung, Ha Uk; Lee, Dong Joon; Shin, Jongmin; Baek, Geun Woo; Kim, Tae-il; Lee, Jong-Ho; Rogers, John A

    2015-04-22

    This paper presents device designs, circuit demonstrations, and dissolution kinetics for amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) comprised completely of water-soluble materials, including SiNx, SiOx, molybdenum, and poly(vinyl alcohol) (PVA). Collections of these types of physically transient a-IGZO TFTs and 5-stage ring oscillators (ROs), constructed with them, show field effect mobilities (∼10 cm2/Vs), on/off ratios (∼2×10(6)), subthreshold slopes (∼220 mV/dec), Ohmic contact properties, and oscillation frequency of 5.67 kHz at supply voltages of 19 V, all comparable to otherwise similar devices constructed in conventional ways with standard, nontransient materials. Studies of dissolution kinetics for a-IGZO films in deionized water, bovine serum, and phosphate buffer saline solution provide data of relevance for the potential use of these materials and this technology in temporary biomedical implants. PMID:25805699

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

    SciTech Connect

    Yang, Tsung-Jui; Wu, Yuh-Renn; Shivaraman, Ravi; Speck, James S.

    2014-09-21

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

  14. Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium

    NASA Astrophysics Data System (ADS)

    Nestoridi, Maria; Pletcher, Derek; Wharton, Julian A.; Wood, Robert J. K.

    As part of a programme to develop a high power density, Al/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell with a large ratio of aluminium alloy to electrolyte, over a range of current densities the extent of dissolution was limited to ∼1000 C cm -2 of anode surface by a thick layer of loosely bound, crystalline deposit on the Al alloy anode formed by precipitation from solution. This leads to a large increase in impedance and acts as a barrier to transport of ions.

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

    SciTech Connect

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

    1980-05-01

    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)

  16. Synthesis of Two New Group 13 Benzoato-Chloro Complexes: A Structural Study of Gallium and Indium Chelating Carboxylates

    NASA Technical Reports Server (NTRS)

    Duraj, Stan A.; Hepp, Aloysius F.; Woloszynek, Robert; Protasiewicz, John D.; Dequeant, Michael; Ren, Tong

    2010-01-01

    Two new heteroleptic chelated-benzoato gallium (III) and indium (III) complexes have been prepared and structurally characterized. The molecular structures of [GaCl2(4-Mepy)2(O2CPh)]4-Mepy (1) and [InCl(4-Mepy)2(O2CPh)2]4-Mepy (2) have been determined by single-crystal x-ray diffraction. The gallium compound (1) is a distorted octahedron with cis-chloride ligands co-planar with the chelating benzoate and the 4-methylpyridines trans to each other. This is the first example of a Ga(III) structure with a chelating benzoate. The indium compound (2) is a distorted pentagonal bipyramid with two chelating benzoates, one 4-methylpyridine in the plane and a chloride trans to the other 4-methylpyridine. The indium bis-benzoate is an unusual example of a seven-coordinate structure with classical ligands. Both complexes, which due to the chelates, could also be described as pseudo-trigonal bipyramidal, include a three-bladed motif with three roughly parallel aromatic rings that along with a solvent of crystallization and electron-withdrawing chloride ligand(s) stabilize the solid-state structures.

  17. Synthesis, Characterization, and Processing of Copper, Indium, and Gallium Dithiocarbamates for Energy Conversion Applications

    NASA Technical Reports Server (NTRS)

    Duraj, S. A.; Duffy, N. V.; Hepp, A. F.; Cowen, J. E.; Hoops, M. D.; Brothrs, S. M.; Baird, M. J.; Fanwick, P. E.; Harris, J. D.; Jin, M. H.-C.

    2009-01-01

    Ten dithiocarbamate complexes of indium(III) and gallium(III) have been prepared and characterized by elemental analysis, infrared spectra and melting point. Each complex was decomposed thermally and its decomposition products separated and identified with the combination of gas chromatography/mass spectrometry. Their potential utility as photovoltaic materials precursors was assessed. Bis(dibenzyldithiocarbamato)- and bis(diethyldithiocarbamato)copper(II), Cu(S2CN(CH2C6H5)2)2 and Cu(S2CN(C2H5)2)2 respectively, have also been examined for their suitability as precursors for copper sulfides for the fabrication of photovoltaic materials. Each complex was decomposed thermally and the products analyzed by GC/MS, TGA and FTIR. The dibenzyl derivative complex decomposed at a lower temperature (225-320 C) to yield CuS as the product. The diethyl derivative complex decomposed at a higher temperature (260-325 C) to yield Cu2S. No Cu containing fragments were noted in the mass spectra. Unusual recombination fragments were observed in the mass spectra of the diethyl derivative. Tris(bis(phenylmethyl)carbamodithioato-S,S'), commonly referred to as tris(N,N-dibenzyldithiocarbamato)indium(III), In(S2CNBz2)3, was synthesized and characterized by single crystal X-ray crystallography. The compound crystallizes in the triclinic space group P1(bar) with two molecules per unit cell. The material was further characterized using a novel analytical system employing the combined powers of thermogravimetric analysis, gas chromatography/mass spectrometry, and Fourier transform infrared (FT-IR) spectroscopy to investigate its potential use as a precursor for the chemical vapor deposition (CVD) of thin film materials for photovoltaic applications. Upon heating, the material thermally decomposes to release CS2 and benzyl moieties in to the gas phase, resulting in bulk In2S3. Preliminary spray CVD experiments indicate that In(S2CNBz2)3 decomposed on a Cu substrate reacts to produce

  18. Nanoscale Synthesis of Two Porphyrin-Based MOFs with Gallium and Indium.

    PubMed

    Rhauderwiek, Timo; Waitschat, Steve; Wuttke, Stefan; Reinsch, Helge; Bein, Thomas; Stock, Norbert

    2016-06-01

    Two porphyrin-based metal-organic frameworks (MOFs) containing gallium or indium, [Ga2(OH)2(H2TCPP)]·3DMF·3H2O (Ga-PMOF) and [In2(OH)2(H2TCPP)]·3DMF·4H2O (In-PMOF) (H6TCPP = 4-tetracarboxyphenylporphyrin), were discovered using high-throughput methods. The structure was refined by the Rietveld-method starting from the structure model of Al-PMOF, [Al2(OH)2(H2TCPP)]. The new PMOFs exhibit BET surface areas between 1150 and 1400 m(2) g(-1) and are also porous toward CO2 (Ga-PMOF, 15.2 wt %; In-PMOF, 12.9 wt %). They are thermally stable in air up to 330 °C, but show limited chemical stabilities toward acids and bases. In order to achieve size control, different synthesis routes were investigated, i.e., batch synthesis at different temperatures (yield: In-PMOF-bs-th 96%, Ga-PMOF-bs-th 87%), ultrasound-assisted synthesis (yield: In-PMOF-bs-us 85%), and continuous-flow synthesis (yield: Ga-PMOF-cf 71%). By using these different methods we could control the nucleation rate and the crystal size. The crystal sizes were found to vary about 60 to 160 nm and 70 to 130 nm for Ga- and In-PMOF, respectively, which was proven by dynamic light scattering (DLS), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements.

  19. Low-frequency noise properties in Pt-indium gallium zinc oxide Schottky diodes

    SciTech Connect

    Zhang, Jiawei; Zhang, Linqing; Ma, Xiaochen; Wilson, Joshua; Jin, Jidong; Du, Lulu; Xin, Qian; Song, Aimin

    2015-08-31

    The low-frequency noise properties of Pt-indium gallium zinc oxide (IGZO) Schottky diodes at different forward biases are investigated. The IGZO layer and Pt contact were deposited by RF sputtering at room temperature. The diode showed an ideality factor of 1.2 and a barrier height of 0.94 eV. The current noise spectral density exhibited 1/f behavior at low frequencies. The analysis of the current dependency of the noise spectral density revealed that for the as-deposited diode, the noise followed Luo's mobility and diffusivity fluctuation model in the thermionic-emission-limited region and Hooge's empirical theory in the series-resistance-limited region. A low Hooge's constant of 1.4 × 10{sup −9} was found in the space-charge region. In the series-resistance-limited region, the Hooge's constant was 2.2 × 10{sup −5}. After annealing, the diode showed degradation in the electrical performance. The interface-trap-induced noise dominated the noise spectrum. By using the random walk model, the interface-trap density was obtained to be 3.6 × 10{sup 15 }eV{sup −1 }cm{sup −2}. This work provides a quantitative approach to analyze the properties of Pt-IGZO interfacial layers. These low noise properties are a prerequisite to the use of IGZO Schottky diodes in switch elements in memory devices, photosensors, and mixer diodes.

  20. Nanoscale Synthesis of Two Porphyrin-Based MOFs with Gallium and Indium.

    PubMed

    Rhauderwiek, Timo; Waitschat, Steve; Wuttke, Stefan; Reinsch, Helge; Bein, Thomas; Stock, Norbert

    2016-06-01

    Two porphyrin-based metal-organic frameworks (MOFs) containing gallium or indium, [Ga2(OH)2(H2TCPP)]·3DMF·3H2O (Ga-PMOF) and [In2(OH)2(H2TCPP)]·3DMF·4H2O (In-PMOF) (H6TCPP = 4-tetracarboxyphenylporphyrin), were discovered using high-throughput methods. The structure was refined by the Rietveld-method starting from the structure model of Al-PMOF, [Al2(OH)2(H2TCPP)]. The new PMOFs exhibit BET surface areas between 1150 and 1400 m(2) g(-1) and are also porous toward CO2 (Ga-PMOF, 15.2 wt %; In-PMOF, 12.9 wt %). They are thermally stable in air up to 330 °C, but show limited chemical stabilities toward acids and bases. In order to achieve size control, different synthesis routes were investigated, i.e., batch synthesis at different temperatures (yield: In-PMOF-bs-th 96%, Ga-PMOF-bs-th 87%), ultrasound-assisted synthesis (yield: In-PMOF-bs-us 85%), and continuous-flow synthesis (yield: Ga-PMOF-cf 71%). By using these different methods we could control the nucleation rate and the crystal size. The crystal sizes were found to vary about 60 to 160 nm and 70 to 130 nm for Ga- and In-PMOF, respectively, which was proven by dynamic light scattering (DLS), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements. PMID:27203724

  1. Electromechanical properties of amorphous indium-gallium-zinc-oxide transistors structured with an island configuration on plastic

    NASA Astrophysics Data System (ADS)

    Park, Chang Bum; Na, Hyung Il; Yoo, Soon Sung; Park, Kwon-Shik

    2016-03-01

    A comparative study of the electromechanical properties was carried out on a low-temperature-processed amorphous indium-gallium-zinc-oxide thin-film transistor, particularly with regard to the structural design of the device under the stress accumulation of an outward bending surface. Shown herein is the reliable electromechanical integrity of island-structured devices against the mechanical strain at bending radii of mm order. The onset of crack strain also closely corresponded to the electrical failure of the stressed device. These results revealed that the island configuration on the bending surface effectively suppresses the stress accumulation on sheets composed of inorganic stacked layers in a uniaxial direction.

  2. Gallium

    SciTech Connect

    1996-01-01

    Discovered in 1875 through a study of its spectral properties, gallium was the first element to be uncovered following the publication of Mendeleev`s Periodic Table. French chemist, P.E. Lecoq de Boisbaudran, named his element discovery in honor of his native country; gallium is derived from the Latin word for France-{open_quotes}Gallia.{close_quotes}. This paper describes the properties, sources, and market for gallium.

  3. Aluminium, gallium, and molybdenum toxicity to the tropical marine microalga Isochrysis galbana.

    PubMed

    Trenfield, Melanie A; van Dam, Joost W; Harford, Andrew J; Parry, David; Streten, Claire; Gibb, Karen; van Dam, Rick A

    2015-08-01

    There is a shortage of established chronic toxicity test methods for assessing the toxicity of contaminants to tropical marine organisms. The authors tested the suitability of the tropical microalga Isochrysis galbana for use in routine ecotoxicology and assessed the effects of 72-h exposures to copper (Cu, a reference toxicant), aluminium (Al), gallium (Ga), and molybdenum (Mo), key metals of alumina refinery discharge, on the growth of I. galbana at 3 temperatures: 24 °C, 28 °C, and 31 °C. The sensitivity of both I. galbana and the test method was validated by the response to Cu exposure, with 10% and 50% effect concentrations (EC10 and EC50) of 2.5 μg/L and 18 μg/L, respectively. The EC10 and EC50 values for total Al at 28 °C were 640 μg/L and 3045 μg/L, respectively. The toxicity of both Cu and Al at 24 °C and 31 °C was similar to that at 28 °C. There was no measurable toxicity from dissolved Ga exposures of up to 6000 μg/L or exposures to dissolved Mo of up to 9500 μg/L. Solubility limits at 28 °C for the dissolved fractions (<10 kDa) of Al, Ga, and Mo were approximately 650 μg/L Al, >7000 μg/L Ga, and >6000 μg/L Mo. In test solutions containing >650 μg/L total Al, dissolved and precipitated forms of Al were present, with precipitated Al becoming more dominant as total Al increased. The test method proved suitable for routine ecotoxicology, with I. galbana showing sensitivity to Cu but Al, Ga, and Mo exhibiting little to no toxicity to this species. PMID:25809393

  4. Aluminium, gallium, and molybdenum toxicity to the tropical marine microalga Isochrysis galbana.

    PubMed

    Trenfield, Melanie A; van Dam, Joost W; Harford, Andrew J; Parry, David; Streten, Claire; Gibb, Karen; van Dam, Rick A

    2015-08-01

    There is a shortage of established chronic toxicity test methods for assessing the toxicity of contaminants to tropical marine organisms. The authors tested the suitability of the tropical microalga Isochrysis galbana for use in routine ecotoxicology and assessed the effects of 72-h exposures to copper (Cu, a reference toxicant), aluminium (Al), gallium (Ga), and molybdenum (Mo), key metals of alumina refinery discharge, on the growth of I. galbana at 3 temperatures: 24 °C, 28 °C, and 31 °C. The sensitivity of both I. galbana and the test method was validated by the response to Cu exposure, with 10% and 50% effect concentrations (EC10 and EC50) of 2.5 μg/L and 18 μg/L, respectively. The EC10 and EC50 values for total Al at 28 °C were 640 μg/L and 3045 μg/L, respectively. The toxicity of both Cu and Al at 24 °C and 31 °C was similar to that at 28 °C. There was no measurable toxicity from dissolved Ga exposures of up to 6000 μg/L or exposures to dissolved Mo of up to 9500 μg/L. Solubility limits at 28 °C for the dissolved fractions (<10 kDa) of Al, Ga, and Mo were approximately 650 μg/L Al, >7000 μg/L Ga, and >6000 μg/L Mo. In test solutions containing >650 μg/L total Al, dissolved and precipitated forms of Al were present, with precipitated Al becoming more dominant as total Al increased. The test method proved suitable for routine ecotoxicology, with I. galbana showing sensitivity to Cu but Al, Ga, and Mo exhibiting little to no toxicity to this species.

  5. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    SciTech Connect

    Lee, Ching-Ting Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-28

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance g{sub m} change, threshold voltage V{sub T} change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  6. High stability mechanisms of quinary indium gallium zinc aluminum oxide multicomponent oxide films and thin film transistors

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Lin, Yung-Hao; Lin, Jhong-Ham

    2015-01-01

    Quinary indium gallium zinc aluminum oxide (IGZAO) multicomponent oxide films were deposited using indium gallium zinc oxide (IGZO) target and Al target by radio frequency magnetron cosputtering system. An extra carrier transport pathway could be provided by the 3 s orbitals of Al cations to improve the electrical properties of the IGZO films, and the oxygen instability could be stabilized by the strong Al-O bonds in the IGZAO films. The electron concentration change and the electron mobility change of the IGZAO films for aging time of 10 days under an air environment at 40 °C and 75% humidity were 20.1% and 2.4%, respectively. The experimental results verified the performance stability of the IGZAO films. Compared with the thin film transistors (TFTs) using conventional IGZO channel layer, in conducting the stability of TFTs with IGZAO channel layer, the transconductance gm change, threshold voltage VT change, and the subthreshold swing S value change under the same aging condition were improved to 7.9%, 10.5%, and 14.8%, respectively. Furthermore, the stable performances of the IGZAO TFTs were also verified by the positive gate bias stress. In this research, the quinary IGZAO multicomponent oxide films and that applied in TFTs were the first studied in the literature.

  7. Testicular toxicity evaluation of arsenic-containing binary compound semiconductors, gallium arsenide and indium arsenide, in hamsters.

    PubMed

    Omura, M; Hirata, M; Tanaka, A; Zhao, M; Makita, Y; Inoue, N; Gotoh, K; Ishinishi, N

    1996-12-16

    The testicular toxicities of gallium arsenide (GaAs), indium arsenide (InAs) and arsenic trioxide (As2O3) were examined by repetitive intratracheal instillation using hamsters. GaAs (7.7 mg/kg) and As2O3 (1.3 mg/kg) were instilled twice a week a total of 16 times and InAs (7.7 mg/kg) was instilled a total of 14 times. GaAs caused testicular spermatid retention and epididymal sperm reduction, though the degrees were less severe than those in rats shown in our previous experiment. InAs and As2O3 did not show any testicular toxicities. Serum arsenic concentration in GaAs-treated hamsters was less than half of that in As2O3-treated hamsters in which no testicular toxicities were found. Serum molar concentration of gallium was 32-times higher than that of arsenic in GaAs-treated hamsters. Therefore gallium may play a main role in the testicular toxicity of GaAs in hamsters.

  8. Metastability of copper indium gallium diselenide polycrystalline thin film solar cell devices

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo

    High efficiency thin film solar cells have the potential for being a world energy solution because of their cost-effectiveness. Looking to the future of solar energy, there is the opportunity and challenge for thin film solar cells. The main theme of this research is to develop a detailed understanding of electronically active defect states and their role in limiting device performance in copper indium gallium diselenide (CIGS) solar cells. Metastability in the CIGS is a good tool to manipulate electronic defect density and thus identify its effect on the device performance. Especially, this approach keeps many device parameters constant, including the chemical composition, grain size, and interface layers. Understanding metastability is likely to lead to the improvement of CIGS solar cells. We observed systematic changes in CIGS device properties as a result of the metastable changes, such as increases in sub-bandgap defect densities and decreases in hole carrier mobilities. Metastable changes were characterized using high frequency admittance spectroscopy, drive-level capacitance profiling (DLCP), and current-voltage measurements. We found two distinctive capacitance steps in the high frequency admittance spectra that correspond to (1) the thermal activation of hole carriers into/out of acceptor defect and (2) a temperature-independent dielectric relaxation freeze-out process and an equivalent circuit analysis was employed to deduce the dielectric relaxation time. Finally, hole carrier mobility was deduced once hole carrier density was determined by DLCP method. We found that metastable defect creation in CIGS films can be made either by light-soaking or with forward bias current injection. The deep acceptor density and the hole carrier density were observed to increase in a 1:1 ratio, which seems to be consistent with the theoretical model of VCu-V Se defect complex suggested by Lany and Zunger. Metastable defect creation kinetics follows a sub-linear power law

  9. Device performances of organic light-emitting diodes with indium tin oxide, gallium zinc oxide, and indium zinc tin oxide anodes deposited at room temperature.

    PubMed

    Lee, Changhun; Ko, Yoonduk; Kim, Youngsung

    2013-12-01

    Thin films of Indium tin oxide (ITO), Gallium zinc oxide (GZO), and Indium zinc tin oxide (IZTO) were deposited on glass substrates by pulsed direct current magnetron sputtering at room temperature. The structural, optical, and electrical properties of the films were investigated towards evaluating their applications as flexible anodes. IZTO films exhibited the lowest resistivity (6.3 x 10(-4) Omega cm). Organic light-emitting diodes (OLEDs) were fabricated using the ITO, GZO, and IZTO films as anode layers. The turn-on voltages at a current density of 4.5 mA/cm2, 5.5 mA/cm2, 6.5 mA/cm2 were 5.5 V, 13.7 V, and 4.7 V for the devices with ITO, GZO, and IZTO anodes, respectively. The best performance was observed with the IZTO film, indicating its suitability as an alternative material for conventional ITO anodes used in OLEDs and flexible displays. PMID:24266182

  10. Routes to ultra-pure alkyls of indium and gallium and their adducts with ethers, phosphines and amines

    NASA Astrophysics Data System (ADS)

    Jones, Anthony C.; Holliday, A. Kenneth; Cole-Hamilton, David J.; Ahmad, M. Munir; Gerrard, Neil D.

    1984-09-01

    Electrolysis of tetrahydrofuran (thf) solutions of dimethylmagnesium containing tetraethylammonium percholrate using a gallium anode gives [Me 3Ga·thf], but higher yields of both [Me 3Ga·thf] and [Me 3In·thf] are obtained on electrolysis of thf solutions of Grignard reagents with sacrificial metal anodes in the absence of a carrying electrolyte. The thf adducts can be converted into adducts with other Lewis bases, [ Me3M· L], M = Ga or In, L = PMe 3, PEt 3, NEt 3, by simple base exchange reactions. Base-free trimethylgallium can be prepared from: (i) reaction of methyl iodide with the intermetallic compound [Mg 5Ga 2] in a high boiling ether; (ii) electrolysis of Grignard reagents in high boiling ethers using sacrificial gallium anodes; (iii) reactions of GaCl 3 with Grignard reagents in high boiling ethers or (iv) ether exchange reaction between [Me 3Ga·OEt 2] and high boiling ethers. All of these reactions lead to adducts between trimethylgallium and the high boiling ether which, on heating, decompose to give base-free trimethylgallium. [Me 3Ga·OEt 2] can be prepared from reaction of Grignard reagents with gallium trichloride in diethylether or from electrolysis of Grignard reagents in diethyl ether using a sacrificial gallium anode. Similar reactions using an indium anode lead to [Me 3In·OEt 2] from which base-free trimethylindium can be liberated using known chemistry. The use of alkyls prepared in this way for vapour phase epitaxy as well as the purity of the alkyls are discussed.

  11. Fabrication of Amorphous Indium Gallium Zinc Oxide Thin Film Transistor by using Focused Ion Beam

    NASA Astrophysics Data System (ADS)

    Zhu, Wencong

    Compared with other transparent semiconductors, amorphous indium gallium zinc oxide (a-IGZO) has both good uniformity and high electron mobility, which make it as a good candidate for displays or large-scale transparent circuit. The goal of this research is to fabricate alpha-IGZO thin film transistor (TFT) with channel milled by focused ion beam (FIB). TFTs with different channel geometries can be achieved by applying different milling strategies, which facilitate modifying complex circuit. Technology Computer-Aided Design (TCAD) was also introduced to understand the effect of trapped charges on the device performance. The investigation of the trapped charge at IGZO/SiO2 interface was performed on the IGZO TFT on p-Silicon substrate with thermally grown SiO2 as dielectric. The subgap density-of-state model was used for the simulation, which includes conduction band-tail trap states and donor-like state in the subgap. The result shows that the de-trapping and donor-state ionization determine the interface trapped charge density at various gate biases. Simulation of IGZO TFT with FIB defined channel on the same substrate was also applied. The drain and source were connected intentionally during metal deposition and separated by FIB milling. Based on the simulation, the Ga ions in SiO2 introduced by the ion beam was drifted by gate bias and affects the saturation drain current. Both side channel and direct channel transparent IGZO TFTs were fabricated on the glass substrate with coated ITO. Higher ion energy (30 keV) was used to etch through the substrate between drain and source and form side channels at the corner of milled trench. Lower ion energy (16 keV) was applied to stop the milling inside IGZO thin film and direct channel between drain and source was created. Annealing after FIB milling removed the residual Ga ions and the devices show switch feature. Direct channel shows higher saturation drain current (~10-6 A) compared with side channel (~10-7 A) because

  12. Short-Term Synaptic Plasticity Regulation in Solution-Gated Indium-Gallium-Zinc-Oxide Electric-Double-Layer Transistors.

    PubMed

    Wan, Chang Jin; Liu, Yang Hui; Zhu, Li Qiang; Feng, Ping; Shi, Yi; Wan, Qing

    2016-04-20

    In the biological nervous system, synaptic plasticity regulation is based on the modulation of ionic fluxes, and such regulation was regarded as the fundamental mechanism underlying memory and learning. Inspired by such biological strategies, indium-gallium-zinc-oxide (IGZO) electric-double-layer (EDL) transistors gated by aqueous solutions were proposed for synaptic behavior emulations. Short-term synaptic plasticity, such as paired-pulse facilitation, high-pass filtering, and orientation tuning, was experimentally emulated in these EDL transistors. Most importantly, we found that such short-term synaptic plasticity can be effectively regulated by alcohol (ethyl alcohol) and salt (potassium chloride) additives. Our results suggest that solution gated oxide-based EDL transistors could act as the platforms for short-term synaptic plasticity emulation. PMID:27007748

  13. Recovery from ultraviolet-induced threshold voltage shift in indium gallium zinc oxide thin film transistors by positive gate bias

    SciTech Connect

    Liu, P.; Chen, T. P.; Li, X. D.; Wong, J. I.; Liu, Z.; Liu, Y.; Leong, K. C.

    2013-11-11

    The effect of short-duration ultraviolet (UV) exposure on the threshold voltage (V{sub th}) of amorphous indium gallium zinc oxide thin film transistors (TFTs) and its recovery characteristics were investigated. The V{sub th} exhibited a significant negative shift after UV exposure. The V{sub th} instability caused by UV illumination is attributed to the positive charge trapping in the dielectric layer and/or at the channel/dielectric interface. The illuminated devices showed a slow recovery in threshold voltage without external bias. However, an instant recovery can be achieved by the application of positive gate pulses, which is due to the elimination of the positive trapped charges as a result of the presence of a large amount of field-induced electrons in the interface region.

  14. Defect generation in amorphous-indium-gallium-zinc-oxide thin-film transistors by positive bias stress at elevated temperature

    SciTech Connect

    Um, Jae Gwang; Mativenga, Mallory; Jang, Jin; Migliorato, Piero

    2014-04-07

    We report on the generation and characterization of a hump in the transfer characteristics of amorphous indium gallium zinc-oxide thin-film transistors by positive bias temperature stress. The hump depends strongly on the gate bias stress at 100 °C. Due to the hump, the positive shift of the transfer characteristic in deep depletion is always smaller that in accumulation. Since, the latter shift is twice the former, with very good correlation, we conclude that the effect is due to creation of a double acceptor, likely to be a cation vacancy. Our results indicate that these defects are located near the gate insulator/active layer interface, rather than in the bulk. Migration of donor defects from the interface towards the bulk may also occur under PBST at 100 °C.

  15. Gallium and indium complexes containing the bis(imino)phenoxide ligand: synthesis, structural characterization and polymerization studies.

    PubMed

    Ghosh, Swarup; Gowda, Ravikumar R; Jagan, Rajamony; Chakraborty, Debashis

    2015-06-14

    A series of gallium and indium complexes containing a bis(imino)phenolate ligand framework were synthesized and completely characterized with different spectroscopic techniques. The molecular structures of a few complexes were determined using single crystal X-ray diffraction studies. These compounds were found to be extremely active towards the bulk ring opening polymerization (ROP) of lactides yielding polymers with high number average molecular weight (Mn) and controlled molecular weight distributions (MWDs). The neutral complexes produce isotactic enriched poly(lactic acid) (PLA) from rac-lactide (rac-LA) under melt conditions, whereas the ionic complex produces atactic PLA. The polymerizations are controlled, as evidenced by the narrow molecular distribution (MWDs) of the isolated polymers in addition to the linear nature of number average molecular weight (Mn) versus conversion plots with variations in monomer to catalyst ratios. The kinetic and mechanistic studies associated with these polymerizations have been performed.

  16. Electrical stress-induced instability of amorphous indium-gallium-zinc oxide thin-film transistors under bipolar ac stress

    SciTech Connect

    Lee, Sangwon; Jeon, Kichan; Park, Jun-Hyun; Kim, Sungchul; Kong, Dongsik; Kim, Dong Myong; Kim, Dae Hwan; Kim, Sangwook; Kim, Sunil; Hur, Jihyun; Park, Jae Chul; Song, Ihun; Kim, Chang Jung; Park, Youngsoo; Jung, U-In

    2009-09-28

    Bipolar ac stress-induced instability of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors is comparatively investigated with that under a positive dc gate bias stress. While the positive dc gate bias stress-induced threshold voltage shift ({delta}V{sub T}) is caused by the charge trapping into the interface/gate dielectric as reported in previous works, the dominant mechanism of the ac stress-induced {delta}V{sub T} is observed to be due to the increase in the acceptorlike deep states of the density of states (DOS) in the a-IGZO active layer. Furthermore, it is found that the variation of deep states in the DOS makes a parallel shift in the I{sub DS}-V{sub GS} curve with an insignificant change in the subthreshold slope, as well as the deformation of the C{sub G}-V{sub G} curves.

  17. One-pot electrodeposition, characterization and photoactivity of stoichiometric copper indium gallium diselenide (CIGS) thin films for solar cells.

    PubMed

    Harati, Mohammad; Jia, Jia; Giffard, Kévin; Pellarin, Kyle; Hewson, Carly; Love, David A; Lau, Woon Ming; Ding, Zhifeng

    2010-12-14

    Herein we report the one-pot electrodeposition of copper indium gallium diselenide, CuIn(1-x)Ga(x)Se(2) (CIGS), thin films as the p-type semiconductor in an ionic liquid medium consisting of choline chloride/urea eutectic mixture known as Reline. The thin films were characterized by scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman microspectroscopy, and UV-visible spectroscopy. Based on the results of the characterizations, the electrochemical bath recipe was optimized to obtain stoichiometric CIGS films with x between 0.2 and 0.4. The chemical activity and photoreactivity of the optimized CIGS films were found to be uniform using scanning electrochemical microscopy and scanning photoelectrochemical microscopy. Low-cost stoichiometric CIGS thin films in one-pot were successfully fabricated. PMID:20835485

  18. Improved characteristics of amorphous indium-gallium-zinc-oxide-based resistive random access memory using hydrogen post-annealing

    NASA Astrophysics Data System (ADS)

    Kang, Dae Yun; Lee, Tae-Ho; Kim, Tae Geun

    2016-08-01

    The authors report an improvement in resistive switching (RS) characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO)-based resistive random access memory devices using hydrogen post-annealing. Because this a-IGZO thin film has oxygen off-stoichiometry in the form of deficient and excessive oxygen sites, the film properties can be improved by introducing hydrogen atoms through the annealing process. After hydrogen post-annealing, the device exhibited a stable bipolar RS, low-voltage set and reset operation, long retention (>105 s), good endurance (>106 cycles), and a narrow distribution in each current state. The effect of hydrogen post-annealing is also investigated by analyzing the sample surface using X-ray photon spectroscopy and atomic force microscopy.

  19. A transparent diode with high rectifying ratio using amorphous indium-gallium-zinc oxide/SiNx coupled junction

    NASA Astrophysics Data System (ADS)

    Choi, Myung-Jea; Kim, Myeong-Ho; Choi, Duck-Kyun

    2015-08-01

    We introduce a transparent diode that shows both high rectifying ratio and low leakage current at process temperature below 250 °C. This device is clearly distinguished from all previous transparent diodes in that the rectifying behavior results from the junction between a semiconductor (amorphous indium-gallium-zinc oxide (a-IGZO)) and insulator (SiNx). We systematically study the properties of each junction within the device structure and demonstrate that the a-IGZO/SiNx junction is the source of the outstanding rectification. The electrical characteristics of this transparent diode are: 2.8 A/cm2 on-current density measured at -7 V; lower than 7.3 × 10-9 A/cm2 off-current density; 2.53 ideality factor; and high rectifying ratio of 108-109. Furthermore, the diode structure has a transmittance of over 80% across the visible light range. The operating principle of the indium-tin oxide (ITO)/a-IGZO/SiNx/ITO device was examined with an aid of the energy band diagram and we propose a preliminary model for the rectifying behavior. Finally, we suggest further directions for research on this transparent diode.

  20. Extraction of gallium(III) from hydrochloric acid solutions by trioctylammonium-based mixed ionic liquids.

    PubMed

    Katsuta, Shoichi; Okai, Miho; Yoshimoto, Yuki; Kudo, Yoshihiro

    2012-01-01

    The extractabilities of aluminium(III), gallium(III), and indium(III) from hydrochloric acid solutions were investigated using a mixture of two protic ionic liquids, trioctylammonium bis(trifluoromethanesulfonyl)amide ([TOAH][NTf(2)]) and trioctylammonium nitrate ([TOAH][NO(3)]). At a HCl concentration of 4 mol L(-1) or more, gallium(III) was nearly quantitatively extracted and the extractability order was Ga > Al > In. The extractability of gallium(III) increased with increasing [TOAH][NO(3)] content in the mixed ionic liquid. The extracted gallium(III) was quantitatively stripped with aqueous nitric acid solutions. The separation and recovery of gallium(III) from hydrochloric acid solutions containing excess indium(III) was demonstrated using the mixed ionic liquid.

  1. Highly Thermostable, Non-oxidizable Indium, Gallium, and Aluminium Perfluorophthalocyanines with n-Type Character.

    PubMed

    Łapok, Łukasz; Obłoza, Magdalena; Nowakowska, Maria

    2016-08-16

    Perfluorophthalocyanines incorporating three-valent metals, namely In(Cl), Ga(Cl), and Al(Cl), have been synthesized and characterized. Thermogravimetric analysis revealed that these compounds exhibit outstanding thermal stability and a tendency to sublime at a temperature exceeding around 350 °C without thermal decomposition. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to probe the frontier orbital energy levels of these compounds in THF solution. All three compounds undergo three quasi-reversible reductions with the first one leading to the formation of an anion radical, namely MPc(-.) , as confirmed by spectroelectrochemistry. The compounds studied were intrinsically resistive to oxidation, which indicates that they are very good electron acceptors (n-type materials). The HOMO-LUMO energy gaps (Eg ) of the three compounds determined by UV/Vis spectroscopy were relatively unaffected by the three-valent metals incorporated into the phthalocyanine macrocycle. Similarly, the energies of the HOMO (EHOMO ) and LUMO (ELUMO ) orbitals remained virtually unaffected by the three-valent metals in the perfluorophthalocyanine. Importantly, all the perfluorophthalocyanines studied possess LUMO levels between -4.76 and -4.85 eV, which makes their reduced forms resistant to electron trapping by O2 and H2 O. This property opens up the possibility for the fabrication of electronic devices operating under ambient conditions. All three compounds demonstrated very good photostability as solid thin films. PMID:27405880

  2. Derived reference doses for three compounds used in the photovoltaics industry: Copper indium diselenide, copper gallium diselenide, and cadmium telluride

    SciTech Connect

    Moskowitz, P.D.; Bernholc, N.; DePhillips, M.P.; Viren, J.

    1995-07-06

    Polycrystalline thin-film photovoltaic modules made from copper indium diselenide (CIS), copper gallium diselenide (CGS), and cadmium telluride (CdTe) arc nearing commercial development. A wide range of issues are being examined as these materials move from the laboratory to large-scale production facilities to ensure their commercial success. Issues of traditional interest include module efficiency, stability and cost. More recently, there is increased focus given to environmental, health and safety issues surrounding the commercialization of these same devices. An examination of the toxicological properties of these materials, and their chemical parents is fundamental to this discussion. Chemicals that can present large hazards to human health or the environment are regulated often more strictly than those that are less hazardous. Stricter control over how these materials are handled and disposed can increase the costs associated with the production and use of these modules dramatically. Similarly, public perception can be strongly influenced by the inherent biological hazard that these materials possess. Thus, this report: presents a brief background tutorial on how toxicological data are developed and used; overviews the toxicological data available for CIS, CGS and CdTe; develops ``reference doses`` for each of these compounds; compares the reference doses for these compounds with those of their parents; discusses the implications of these findings to photovoltaics industry.

  3. Activation of sputter-processed indium-gallium-zinc oxide films by simultaneous ultraviolet and thermal treatments

    NASA Astrophysics Data System (ADS)

    Tak, Young Jun; Du Ahn, Byung; Park, Sung Pyo; Kim, Si Joon; Song, Ae Ran; Chung, Kwun-Bum; Kim, Hyun Jae

    2016-02-01

    Indium-gallium-zinc oxide (IGZO) films, deposited by sputtering at room temperature, still require activation to achieve satisfactory semiconductor characteristics. Thermal treatment is typically carried out at temperatures above 300 °C. Here, we propose activating sputter- processed IGZO films using simultaneous ultraviolet and thermal (SUT) treatments to decrease the required temperature and enhance their electrical characteristics and stability. SUT treatment effectively decreased the amount of carbon residues and the number of defect sites related to oxygen vacancies and increased the number of metal oxide (M-O) bonds through the decomposition-rearrangement of M-O bonds and oxygen radicals. Activation of IGZO TFTs using the SUT treatment reduced the processing temperature to 150 °C and improved various electrical performance metrics including mobility, on-off ratio, and threshold voltage shift (positive bias stress for 10,000 s) from 3.23 to 15.81 cm2/Vs, 3.96 × 107 to 1.03 × 108, and 11.2 to 7.2 V, respectively.

  4. Activation of sputter-processed indium-gallium-zinc oxide films by simultaneous ultraviolet and thermal treatments.

    PubMed

    Tak, Young Jun; Ahn, Byung Du; Park, Sung Pyo; Kim, Si Joon; Song, Ae Ran; Chung, Kwun-Bum; Kim, Hyun Jae

    2016-01-01

    Indium-gallium-zinc oxide (IGZO) films, deposited by sputtering at room temperature, still require activation to achieve satisfactory semiconductor characteristics. Thermal treatment is typically carried out at temperatures above 300 °C. Here, we propose activating sputter- processed IGZO films using simultaneous ultraviolet and thermal (SUT) treatments to decrease the required temperature and enhance their electrical characteristics and stability. SUT treatment effectively decreased the amount of carbon residues and the number of defect sites related to oxygen vacancies and increased the number of metal oxide (M-O) bonds through the decomposition-rearrangement of M-O bonds and oxygen radicals. Activation of IGZO TFTs using the SUT treatment reduced the processing temperature to 150 °C and improved various electrical performance metrics including mobility, on-off ratio, and threshold voltage shift (positive bias stress for 10,000 s) from 3.23 to 15.81 cm(2)/Vs, 3.96 × 10(7) to 1.03 × 10(8), and 11.2 to 7.2 V, respectively. PMID:26902863

  5. Crystallization behavior of amorphous indium-gallium-zinc-oxide films and its effects on thin-film transistor performance

    NASA Astrophysics Data System (ADS)

    Suko, Ayaka; Jia, JunJun; Nakamura, Shin-ichi; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki; Shigesato, Yuzo

    2016-03-01

    Amorphous indium-gallium-zinc oxide (a-IGZO) films were deposited by DC magnetron sputtering and post-annealed in air at 300-1000 °C for 1 h to investigate the crystallization behavior in detail. X-ray diffraction, electron beam diffraction, and high-resolution electron microscopy revealed that the IGZO films showed an amorphous structure after post-annealing at 300 °C. At 600 °C, the films started to crystallize from the surface with c-axis preferred orientation. At 700-1000 °C, the films totally crystallized into polycrystalline structures, wherein the grains showed c-axis preferred orientation close to the surface and random orientation inside the films. The current-gate voltage (Id-Vg) characteristics of the IGZO thin-film transistor (TFT) showed that the threshold voltage (Vth) and subthreshold swing decreased markedly after the post-annealing at 300 °C. The TFT using the totally crystallized films also showed the decrease in Vth, whereas the field-effect mobility decreased considerably.

  6. Coplanar amorphous-indium-gallium-zinc-oxide thin film transistor with He plasma treated heavily doped layer

    SciTech Connect

    Jeong, Ho-young; Lee, Bok-young; Lee, Young-jang; Lee, Jung-il; Yang, Myoung-su; Kang, In-byeong; Mativenga, Mallory; Jang, Jin

    2014-01-13

    We report thermally stable coplanar amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with heavily doped n{sup +} a-IGZO source/drain regions. Doping is through He plasma treatment in which the resistivity of the a-IGZO decreases from 2.98 Ω cm to 2.79 × 10{sup −3} Ω cm after treatment, and then it increases to 7.92 × 10{sup −2} Ω cm after annealing at 300 °C. From the analysis of X-ray photoelectron spectroscopy, the concentration of oxygen vacancies in He plasma treated n{sup +}a-IGZO does not change much after thermal annealing at 300 °C, indicating thermally stable n{sup +} a-IGZO, even for TFTs with channel length L = 4 μm. Field-effect mobility of the coplanar a-IGZO TFTs with He plasma treatment changes from 10.7 to 9.2 cm{sup 2}/V s after annealing at 300 °C, but the performance of the a-IGZO TFT with Ar or H{sub 2} plasma treatment degrades significantly after 300 °C annealing.

  7. Stabilities of amorphous indium gallium zinc oxide thin films under light illumination with various wavelengths and intensities

    NASA Astrophysics Data System (ADS)

    Kim, Ju-Yeon; Jeong, So Hyeon; Yu, Kyeong Min; Yun, Eui-Jung; Bae, Byung Seong

    2014-08-01

    We investigated the photo responses of an amorphous indium gallium zinc oxide (a-IGZO) thin film under light illumination with various wavelengths and intensities. By using the measured photo-conductivities of a-IGZO thin films, we extracted the photo excitation activation energy and dark relaxation activation energy through extended stretched exponential analysis. The stretched exponential analysis was found to describe well both the photoexcitation and the dark-relaxation characteristics. These analyses indicated that recombination takes place more slowly and through activation processes that are more deeply bound with the broader distribution of activation energies (Eac) than those corresponding to the photo-generation process. The longer wavelength of the incident light, the slower the dark-relaxation occurs because of the formation of higher Eac for the ionized oxygen vacancy (Vo2+) states. For the dark-relaxation process, we also observed that the stretching exponent increases and the distribution of energy levels became narrower for longer wavelengths. This suggests that the neutralization of Vo2+ to Vo is slower for longer wavelengths due to the higher energy barrier height (Eac) for the neutralization of Vo2+.

  8. Semiconductor to metallic transition in bulk accumulated amorphous indium-gallium-zinc-oxide dual gate thin-film transistor

    SciTech Connect

    Chun, Minkyu; Chowdhury, Md Delwar Hossain; Jang, Jin

    2015-05-15

    We investigated the effects of top gate voltage (V{sub TG}) and temperature (in the range of 25 to 70 {sup o}C) on dual-gate (DG) back-channel-etched (BCE) amorphous-indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) characteristics. The increment of V{sub TG} from -20V to +20V, decreases the threshold voltage (V{sub TH}) from 19.6V to 3.8V and increases the electron density to 8.8 x 10{sup 18}cm{sup −3}. Temperature dependent field-effect mobility in saturation regime, extracted from bottom gate sweep, show a critical dependency on V{sub TG}. At V{sub TG} of 20V, the mobility decreases from 19.1 to 15.4 cm{sup 2}/V ⋅ s with increasing temperature, showing a metallic conduction. On the other hand, at V{sub TG} of - 20V, the mobility increases from 6.4 to 7.5cm{sup 2}/V ⋅ s with increasing temperature. Since the top gate bias controls the position of Fermi level, the temperature dependent mobility shows metallic conduction when the Fermi level is above the conduction band edge, by applying high positive bias to the top gate.

  9. Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

    NASA Astrophysics Data System (ADS)

    Wissman, J.; Finkenauer, L.; Deseri, L.; Majidi, C.

    2014-10-01

    We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K <0). Applying voltage Φ to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ϑ. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of Φ. Based on this theory, we predict a dependency of ϑ on Φ that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

  10. Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes

    SciTech Connect

    Wissman, J.; Finkenauer, L.; Deseri, L.; Majidi, C.

    2014-10-14

    We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K<0). Applying voltage Φ to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ϑ. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of Φ. Based on this theory, we predict a dependency of ϑ on Φ that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

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

    SciTech Connect

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

    2012-08-01

    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.

  12. Printed indium gallium zinc oxide transistors. Self-assembled nanodielectric effects on low-temperature combustion growth and carrier mobility.

    PubMed

    Everaerts, Ken; Zeng, Li; Hennek, Jonathan W; Camacho, Diana I; Jariwala, Deep; Bedzyk, Michael J; Hersam, Mark C; Marks, Tobin J

    2013-11-27

    Solution-processed amorphous oxide semiconductors (AOSs) are emerging as important electronic materials for displays and transparent electronics. We report here on the fabrication, microstructure, and performance characteristics of inkjet-printed, low-temperature combustion-processed, amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) grown on solution-processed hafnia self-assembled nanodielectrics (Hf-SANDs). TFT performance for devices processed below 300 °C includes >4× enhancement in electron mobility (μFE) on Hf-SAND versus SiO2 or ALD-HfO2 gate dielectrics, while other metrics such as subthreshold swing (SS), current on:off ratio (ION:IOFF), threshold voltage (Vth), and gate leakage current (Ig) are unchanged or enhanced. Thus, low voltage IGZO/SAND TFT operation (<2 V) is possible with ION:IOFF = 10(7), SS = 125 mV/dec, near-zero Vth, and large electron mobility, μFE(avg) = 20.6 ± 4.3 cm(2) V(-1) s(-1), μFE(max) = 50 cm(2) V(-1) s(-1). Furthermore, X-ray diffraction analysis indicates that the 300 °C IGZO combustion processing leaves the underlying Hf-SAND microstructure and capacitance intact. This work establishes the compatibility and advantages of all-solution, low-temperature fabrication of inkjet-printed, combustion-derived high-mobility IGZO TFTs integrated with self-assembled hybrid organic-inorganic nanodielectrics.

  13. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

    PubMed

    Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

    2016-02-01

    Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. PMID:26615488

  14. High-Performance Inkjet-Printed Indium-Gallium-Zinc-Oxide Transistors Enabled by Embedded, Chemically Stable Graphene Electrodes.

    PubMed

    Secor, Ethan B; Smith, Jeremy; Marks, Tobin J; Hersam, Mark C

    2016-07-13

    Recent developments in solution-processed amorphous oxide semiconductors have established indium-gallium-zinc-oxide (IGZO) as a promising candidate for printed electronics. A key challenge for this vision is the integration of IGZO thin-film transistor (TFT) channels with compatible source/drain electrodes using low-temperature, solution-phase patterning methods. Here we demonstrate the suitability of inkjet-printed graphene electrodes for this purpose. In contrast to common inkjet-printed silver-based conductive inks, graphene provides a chemically stable electrode-channel interface. Furthermore, by embedding the graphene electrode between two consecutive IGZO printing passes, high-performance IGZO TFTs are achieved with an electron mobility of ∼6 cm(2)/V·s and current on/off ratio of ∼10(5). The resulting printed devices exhibit robust stability to aging in ambient as well as excellent resilience to thermal stress, thereby offering a promising platform for future printed electronics applications. PMID:27327555

  15. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    PubMed

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics. PMID:27430635

  16. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    PubMed

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

  17. Channel length dependence of negative-bias-illumination-stress in amorphous-indium-gallium-zinc-oxide thin-film transistors

    SciTech Connect

    Um, Jae Gwang; Mativenga, Mallory; Jang, Jin; Migliorato, Piero

    2015-06-21

    We have investigated the dependence of Negative-Bias-illumination-Stress (NBIS) upon channel length, in amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The negative shift of the transfer characteristic associated with NBIS decreases for increasing channel length and is practically suppressed in devices with L = 100-μm. The effect is consistent with creation of donor defects, mainly in the channel regions adjacent to source and drain contacts. Excellent agreement with experiment has been obtained by an analytical treatment, approximating the distribution of donors in the active layer by a double exponential with characteristic length L{sub D} ∼ L{sub n} ∼ 10-μm, the latter being the electron diffusion length. The model also shows that a device with a non-uniform doping distribution along the active layer is in all equivalent, at low drain voltages, to a device with the same doping averaged over the active layer length. These results highlight a new aspect of the NBIS mechanism, that is, the dependence of the effect upon the relative magnitude of photogenerated holes and electrons, which is controlled by the device potential/band profile. They may also provide the basis for device design solutions to minimize NBIS.

  18. Development of a unique laboratory standard: Indium gallium arsenide detector for the 500-1700 nm spectral region

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A planar (5 mm diameter) indium gallium arsenide detector having a high (greater than 50 pct) quantum efficiency from the visible into the infrared spectrum (500 to 1700 nm) was fabricated. Quantum efficiencies as high as 37 pct at 510 nm, 58 pct at 820 nm and 62 pct at 1300 nm and 1550 nm were measured. A planar InP/InGaAs detector structure was also fabricated using vapor phase epitaxy to grow device structures with 0, 0.2, 0.4 and 0.6 micrometer thick InP caps. Quantum efficiency was studied as a function of cap thickness. Conventional detector structures were also used by completely etching off the InP cap after zinc diffusion. Calibrated quantum efficiencies were measured. Best results were obtained with devices whose caps were completely removed by etching. Certain problems still remain with these detectors including non-uniform shunt resistance, reproducibility, contact resistance and narrow band anti-reflection coatings.

  19. Temperature-dependent bias-stress-induced electrical instability of amorphous indium-gallium-zinc-oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Qian, Hui-Min; Yu, Guang; Lu, Hai; Wu, Chen-Fei; Tang, Lan-Feng; Zhou, Dong; Ren, Fang-Fang; Zhang, Rong; Zheng, You-Liao; Huang, Xiao-Ming

    2015-07-01

    The time and temperature dependence of threshold voltage shift under positive-bias stress (PBS) and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. It is found that the time dependence of threshold voltage shift can be well described by a stretched exponential equation in which the time constant τ is found to be temperature dependent. Based on Arrhenius plots, an average effective energy barrier Eτstress = 0.72 eV for the PBS process and an average effective energy barrier Eτrecovery = 0.58 eV for the recovery process are extracted respectively. A charge trapping/detrapping model is used to explain the threshold voltage shift in both the PBS and the recovery process. The influence of gate bias stress on transistor performance is one of the most critical issues for practical device development. Project supported by the National Basic Research Program of China (Grant Nos. 2011CB301900 and 2011CB922100) and the Priority Academic Program Development of Jiangsu Higher Education Institutions, China

  20. Role of phosphate-containing compounds in the transfer of indium-111 and gallium-67 from transferrin to ferritin.

    PubMed

    Weiner, R E

    1989-01-01

    Physiologic concentrations of ATP stimulate the translocation of gallium-67 (67Ga) from human transferrin (TF) to horse ferritin (HoFE). The mechanism of this translocation was examined. One millimolar ATP did not speed the binding of 67Ga or indium-111 (111In) to HoFE. ATP and pyrophosphate (PPi) at 1 mM, did not form high affinity complexes with 67Ga or 111In. ATP and PPi interacted directly with the [67Ga]TF complex and could within minutes increase the amount of nonprotein-bound 67Ga. Serum HCO3- concentration, 30 mM, prevented the ATP-induced dissociation of 67Ga from TF, whereas intracellular concentrations (0.4 and 5 mM) did not. Using a dialysis technique, ATP also stimulated the translocation of 111In from TF to HoFE; however, this process was much slower than with 67Ga. ATP caused an increase in the nonprotein-bound 111In compared to the control. These results suggest the formation of nonprotein-bound nuclide by these phosphate-containing compounds in a kinetically labile form is important to the translocation mechanism. PMID:2536083

  1. Improvement in gate bias stress instability of amorphous indium-gallium-zinc oxide thin-film transistors using microwave irradiation

    SciTech Connect

    Jo, Kwang-Won; Cho, Won-Ju

    2014-11-24

    In this study, we evaluated the effects of microwave irradiation (MWI) post-deposition-annealing (PDA) treatment on the gate bias stress instability of amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) and compared the results with a conventional thermal annealing PDA treatment. The MWI-PDA-treated a-IGZO TFTs exhibited enhanced electrical performance as well as improved long-term stability with increasing microwave power. The positive turn-on voltage shift (ΔV{sub ON}) as a function of stress time with positive bias and varying temperature was precisely modeled on a stretched-exponential equation, suggesting that charge trapping is a dominant mechanism in the instability of MWI-PDA-treated a-IGZO TFTs. The characteristic trapping time and average effective barrier height for electron transport indicate that the MWI-PDA treatment effectively reduces the defects in a-IGZO TFTs, resulting in a superior resistance against gate bias stress.

  2. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells.

    PubMed

    Brun, Nadja Rebecca; Wehrli, Bernhard; Fent, Karl

    2016-02-01

    Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L(-1) molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L(-1). From OPV, copper (14 μg L(-1)), zinc (87 μg L(-1)) and silver (78 μg L(-1)) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk.

  3. Contact resistance asymmetry of amorphous indium-gallium-zinc-oxide thin-film transistors by scanning Kelvin probe microscopy

    NASA Astrophysics Data System (ADS)

    Chen-Fei, Wu; Yun-Feng, Chen; Hai, Lu; Xiao-Ming, Huang; Fang-Fang, Ren; Dun-Jun, Chen; Rong, Zhang; You-Dou, Zheng

    2016-05-01

    In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain (S/D) series resistance in operating amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metal-semiconductor junction. Project supported by the Key Industrial R&D Program of Jiangsu Province, China (Grant No. BE2015155), the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province, China, and the Fundamental Research Funds for the Central Universities, China (Grant No. 021014380033).

  4. Impact of severe cracked germanium (111) substrate on aluminum indium gallium phosphate light-emitting-diode's electro-optical performance

    NASA Astrophysics Data System (ADS)

    Annaniah, Luruthudass; Devarajan, Mutharasu

    2016-07-01

    Cracked die is a serious failure mode in the Light Emitting Diode (LED) industry - affecting LED quality and long-term reliability performance. In this paper an investigation has been carried out to find the correlation between severe cracked germanium (Ge) substrate of an aluminum indium gallium phosphate (AlInGaP) LED and its electro-optical performance after the Temperature Cycle (TC) test. The LED dice were indented at several bond forces using a die bonder. The indented dice were analysed using a Scanning Electron Microscope (SEM). The result showed that severe cracks were observed at 180 gF onward. As the force of indentation increases, crack formation also becomes more severe thus resulting in the chipping of the substrate. The cracked dies were packaged and the TC test was performed. The results did not show any electro-optical failure or degradation, even after a 1000 cycle TC test. Several mechanically cross-sectioned cracked die LEDs, were analysed using SEM and found that no crack reached the active layer. This shows that severely cracked Ge substrate are able to withstand a -40°C/+100°C TC test up to 1000 cycles and LED optical performance is not affected. A small leakage current was observed in all of the cracked die LEDs in comparison to the reference unit. However, this value is smaller than the product specification and is of no concern.

  5. Studies on the best alkaline electrolyte for aluminium/air batteries

    NASA Astrophysics Data System (ADS)

    Kapali, V.; Venkatakrishna Iyer, S.; Balaramachandran, V.; Sarangapani, K. B.; Ganesan, M.; Anbu Kulandainathan, M.; Sheik Mideen, A.

    Two types of alkaline electrolyte, based on 4 M NaOH have been developed for use in aluminium/air cells or batteries. They contain either alkaline citrate or alkaline citrate cum stannate as an additive to suppress the self-corrosion of aluminium without any deleterious effects on the efficient functioning of aluminium anode at a high negative potential. The alkaline citrate cum stannate solution has been adjudged the best electrolyte in terms of electrochemical characteristics and electrolyte management. Hence, results pertaining to the use of alkaline citrate cum stannate are presented in this paper. An aluminium/air battery with this electrolyte can be used safely and effectively at ambient temperature. An added advantage is the employment of 99.8% pure aluminium for the preparation of alloy anodes. This is expected to reduce the cost of aluminium/air batteries. The best anode based on 99.8% pure aluminium is a quaternary alloy containing lead, gallium and indium.

  6. Comparison of indium-labeled-leukocyte imaging with sequential technetium-gallium scanning in the diagnosis of low-grade musculoskeletal sepsis. A prospective study

    SciTech Connect

    Merkel, K.D.; Brown, M.L.; Dewanjee, M.K.; Fitzgerald, R.H. Jr.

    1985-03-01

    We prospectively compared sequential technetium-gallium imaging with indium-labeled-leukocyte imaging in fifty patients with suspected low-grade musculoskeletal sepsis. Adequate images and follow-up examinations were obtained for forty-two patients. The presence or absence of low-grade sepsis was confirmed by histological and bacteriological examinations of tissue specimens taken at surgery in thirty of the forty-two patients. In these thirty patients, the sensitivity of sequential Tc-Ga imaging was 48 per cent, the specificity was 86 per cent, and the accuracy was 57 per cent, whereas the sensitivity of the indium-labeled-leukocyte technique was 83 per cent, the specificity was 86 per cent, and the accuracy was 83 per cent. When the additional twelve patients for whom surgery was deemed unnecessary were considered, the sensitivity of sequential Tc-Ga imaging was 50 per cent, the specificity was 78 per cent, and the accuracy was 62 per cent, as compared with a sensitivity of 83 per cent, a specificity of 94 per cent, and an accuracy of 88 per cent with the indium-labeled-leukocyte method. In patients with a prosthesis the indium-labeled-leukocyte image was 94 per cent accurate, compared with 75 per cent accuracy for sequential Tc-Ga imaging. Statistical analysis of these data demonstrated that the indium-labeled-leukocyte technique was superior to sequential Tc-Ga imaging in detecting areas of low-grade musculoskeletal sepsis.

  7. Comparison of the electronic structure of amorphous versus crystalline indium gallium zinc oxide semiconductor: structure, tail states and strain effects

    NASA Astrophysics Data System (ADS)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2015-11-01

    We study the evolution of the structural and electronic properties of crystalline indium gallium zinc oxide (IGZO) upon amorphization by first-principles calculation. The bottom of the conduction band (BCB) is found to be constituted of a pseudo-band of molecular orbitals that resonate at the same energy on different atomic sites. They display a bonding character between the s orbitals of the metal sites and an anti-bonding character arising from the interaction between the oxygen and metal s orbitals. The energy level of the BCB shifts upon breaking of the crystal symmetry during the amorphization process, which may be attributed to the reduction of the coordination of the cationic centers. The top of the valence band (TVB) is constructed from anti-bonding oxygen p orbitals. In the amorphous state, they have random orientation, in contrast to the crystalline state. This results in the appearance of localized tail states in the forbidden gap above the TVB. Zinc is found to play a predominant role in the generation of these tail states, while gallium hinders their formation. Last, we study the dependence of the fundamental gap and effective mass of IGZO on mechanical strain. The variation of the gap under strain arises from the enhancement of the anti-bonding interaction in the BCB due to the modification of the length of the oxygen-metal bonds and/or to a variation of the cation coordination. This effect is less pronounced for the amorphous material compared to the crystalline material, making amorphous IGZO a semiconductor of choice for flexible electronics. Finally, the effective mass is found to increase upon strain, in contrast to regular materials. This counterintuitive variation is due to the reduction of the electrostatic shielding of the cationic centers by oxygen, leading to an increase of the overlaps between the metal orbitals at the origin of the delocalization of the BCB. For the range of strain typically met in flexible electronics, the induced

  8. Microscopic structure and electrical transport property of sputter-deposited amorphous indium-gallium-zinc oxide semiconductor films

    NASA Astrophysics Data System (ADS)

    Yabuta, H.; Kaji, N.; Shimada, M.; Aiba, T.; Takada, K.; Omura, H.; Mukaide, T.; Hirosawa, I.; Koganezawa, T.; Kumomi, H.

    2014-06-01

    We report on microscopic structures and electrical and optical properties of sputter-deposited amorphous indium-gallium-zinc oxide (a-IGZO) films. From electron microscopy observations and an x-ray small angle scattering analysis, it has been confirmed that the sputtered a-IGZO films consist of a columnar structure. However, krypton gas adsorption measurement revealed that boundaries of the columnar grains are not open-pores. The conductivity of the sputter-deposited a-IGZO films shows a change as large as seven orders of magnitude depending on post-annealing atmosphere; it is increased by N2-annealing and decreased by O2-annealing reversibly, at a temperature as low as 300°C. This large variation in conductivity is attributed to thermionic emission of carrier electrons through potential barriers at the grain boundaries, because temperature dependences of the carrier density and the Hall mobility exhibit thermal activation behaviours. The optical band-gap energy of the a-IGZO films changes between before and after annealing, but is independent of the annealing atmosphere, in contrast to the noticeable dependence of conductivity described above. For exploring other possibilities of a-IGZO, we formed multilayer films with an artificial periodic lattice structure consisting of amorphous InO, GaO, and ZnO layers, as an imitation of the layer-structured InGaZnO4 homologous phase. The hall mobility of the multilayer films was almost constant for thicknesses of the constituent layer between 1 and 6 Å, suggesting rather small contribution of lateral two-dimensional conduction It increased with increasing the thickness in the range from 6 to 15 Å, perhaps owing to an enhancement of two-dimensional conduction in InO layers.

  9. Thermodynamics of reaction of praseodymium with gallium-indium eutectic alloy

    NASA Astrophysics Data System (ADS)

    Melchakov, S. Yu.; Ivanov, V. A.; Yamshchikov, L. F.; Volkovich, V. A.; Osipenko, A. G.; Kormilitsyn, M. V.

    2013-06-01

    Thermodynamic properties of Ga-In eutectic alloys saturated with praseodymium were determined for the first time employing the electromotive force method. The equilibrium potentials of the Pr-In alloys saturated with praseodymium (8.7-12.1 mol.% Pr) and Pr-Ga-In alloys (containing 0.0012-6.71 mol.% Pr) were measured between 573-1073 K. Pr-In alloy containing solid PrIn3 with known thermodynamic properties was used as the reference electrode when measuring the potentials of ternary Pr-In-Ga alloys. Activity, partial and excessive thermodynamic functions of praseodymium in alloys with indium and Ga-In eutectic were calculated. Activity (a), activity coefficients (γ) and solubility (X) of praseodymium in the studied temperature range can be expressed by the following equations: lgaα-Pr(In) = 4.425 - 11965/T ± 0.026. lgаα-Pr(Ga-In) = 5.866 - 14766/T ± 0.190. lgγα-Pr(Ga-In) = 2.351 - 9996/T ± 0.39. lgХPr(Ga-In) = 3.515 - 4770/T ± 0.20.

  10. Thin film metallic glass as a diffusion barrier for copper indium gallium selenide solar cell on stainless steel substrate: A feasibility study

    NASA Astrophysics Data System (ADS)

    Diyatmika, Wahyu; Xue, Lingjun; Lin, Tai-Nan; Chang, Chia-wen; Chu, Jinn P.

    2016-08-01

    The feasibility of using Zr53.5Cu29.1Al6.5Ni10.9 thin-film metallic glass (TFMG) as a diffusion barrier for copper indium gallium selenide (CIGS) solar cells on stainless steel (SS) is investigated. The detrimental Fe diffusion from SS into CIGS is found to be effectively hindered by the introduction of a 70-nm-thick TFMG barrier; the cell performance is thus improved. Compared with the 2.73% of CIGS on bare SS, a higher efficiency of 5.25% is obtained for the cell with the Zr52Cu32Al9Ni7 TFMG barrier.

  11. Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

    PubMed

    Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

    2016-04-01

    Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+. PMID:27451659

  12. Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

    PubMed

    Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

    2016-04-01

    Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+.

  13. The 3-5 semiconductor solid solution single crystal growth. [low gravity float zone growth experiments using gallium indium antimonides and cadmium tellurides

    NASA Technical Reports Server (NTRS)

    Gertner, E. R.

    1980-01-01

    Techniques used for liquid and vapor phase epitaxy of gallium indium arsenide are described and the difficulties encountered are examined. Results show that the growth of bulk III-V solid solution single crystals in a low gravity environment will not have a major technological impact. The float zone technique in a low gravity environment is demonstrated using cadmium telluride. It is shown that this approach can result in the synthesis of a class of semiconductors that can not be grown in normal gravity because of growth problems rooted in the nature of their phase diagrams.

  14. Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides

    NASA Astrophysics Data System (ADS)

    Morales, Daniel; Stoute, Nicholas A.; Yu, Zhiyuan; Aspnes, David E.; Dickey, Michael D.

    2016-08-01

    Liquid metals based on gallium are promising materials for soft, stretchable, and shape reconfigurable electromagnetic devices. The behavior of these metals relates directly to the thicknesses of their surface oxide layers, which can be determined nondestructively by ellipsometry if their dielectric functions ɛ are known. This paper reports on the dielectric functions of liquid gallium and the eutectic gallium indium (EGaIn) alloy from 1.24 to 3.1 eV at room temperature, measured by spectroscopic ellipsometry. Overlayer-induced artifacts, a continuing problem in optical measurements of these highly reactive metals, are eliminated by applying an electrochemically reductive potential to the surface of the metal immersed in an electrolyte. This technique enables measurements at ambient conditions while avoiding the complications associated with removing overlayers in a vacuum environment. The dielectric responses of both metals are closely represented by the Drude model. The EGaIn data suggest that in the absence of an oxide the surface is In-enriched, consistent with the previous vacuum-based studies. Possible reasons for discrepancies with previous measurements are discussed.

  15. Arsenic (III, V), indium (III), and gallium (III) toxicity to zebrafish embryos using a high-throughput multi-endpoint in vivo developmental and behavioral assay.

    PubMed

    Olivares, Christopher I; Field, Jim A; Simonich, Michael; Tanguay, Robert L; Sierra-Alvarez, Reyes

    2016-04-01

    Gallium arsenide (GaAs), indium gallium arsenide (InGaAs) and other III/V materials are finding increasing application in microelectronic components. The rising demand for III/V-based products is leading to increasing generation of effluents containing ionic species of gallium, indium, and arsenic. The ecotoxicological hazard potential of these streams is unknown. While the toxicology of arsenic is comprehensive, much less is known about the effects of In(III) and Ga(III). The embryonic zebrafish was evaluated for mortality, developmental abnormalities, and photomotor response (PMR) behavior changes associated with exposure to As(III), As(V), Ga(III), and In(III). The As(III) lowest observable effect level (LOEL) for mortality was 500 μM at 24 and 120 h post fertilization (hpf). As(V) exposure was associated with significant mortality at 63 μM. The Ga(III)-citrate LOEL was 113 μM at 24 and 120 hpf. There was no association of significant mortality over the tested range of In(III)-citrate (56-900 μM) or sodium citrate (213-3400 μM) exposures. Only As(V) resulted in significant developmental abnormalities with LOEL of 500 μM. Removal of the chorion prior to As(III) and As(V) exposure was associated with increased incidence of mortality and developmental abnormality suggesting that the chorion may normally attenuate mass uptake of these metals by the embryo. Finally, As(III), As(V), and In(III) caused PMR hypoactivity (49-69% of control PMR) at 900-1000 μM. Overall, our results represent the first characterization of multidimensional toxicity effects of III/V ions in zebrafish embryos helping to fill a significant knowledge gap, particularly in Ga(III) and In(III) toxicology.

  16. Arsenic (III, V), indium (III), and gallium (III) toxicity to zebrafish embryos using a high-throughput multi-endpoint in vivo developmental and behavioral assay.

    PubMed

    Olivares, Christopher I; Field, Jim A; Simonich, Michael; Tanguay, Robert L; Sierra-Alvarez, Reyes

    2016-04-01

    Gallium arsenide (GaAs), indium gallium arsenide (InGaAs) and other III/V materials are finding increasing application in microelectronic components. The rising demand for III/V-based products is leading to increasing generation of effluents containing ionic species of gallium, indium, and arsenic. The ecotoxicological hazard potential of these streams is unknown. While the toxicology of arsenic is comprehensive, much less is known about the effects of In(III) and Ga(III). The embryonic zebrafish was evaluated for mortality, developmental abnormalities, and photomotor response (PMR) behavior changes associated with exposure to As(III), As(V), Ga(III), and In(III). The As(III) lowest observable effect level (LOEL) for mortality was 500 μM at 24 and 120 h post fertilization (hpf). As(V) exposure was associated with significant mortality at 63 μM. The Ga(III)-citrate LOEL was 113 μM at 24 and 120 hpf. There was no association of significant mortality over the tested range of In(III)-citrate (56-900 μM) or sodium citrate (213-3400 μM) exposures. Only As(V) resulted in significant developmental abnormalities with LOEL of 500 μM. Removal of the chorion prior to As(III) and As(V) exposure was associated with increased incidence of mortality and developmental abnormality suggesting that the chorion may normally attenuate mass uptake of these metals by the embryo. Finally, As(III), As(V), and In(III) caused PMR hypoactivity (49-69% of control PMR) at 900-1000 μM. Overall, our results represent the first characterization of multidimensional toxicity effects of III/V ions in zebrafish embryos helping to fill a significant knowledge gap, particularly in Ga(III) and In(III) toxicology. PMID:26824274

  17. The in vitro photodynamic effect of laser activated gallium, indium and iron phthalocyanine chlorides on human lung adenocarcinoma cells.

    PubMed

    Maduray, K; Odhav, B

    2013-11-01

    Metal-based phthalocyanines currently are utilized as a colorant for industrial applications but their unique properties also make them prospective photosensitizers. Photosensitizers are non-toxic drugs, which are commonly used in photodynamic therapy (PDT), for the treatment of various cancers. PDT is based on the principle that, exposure to light shortly after photosensitizer administration predominately leads to the production of reactive oxygen species for the eradication of cancerous cells and tissue. This in vitro study investigated the photodynamic effect of gallium (GaPcCl), indium (InPcCl) and iron (FePcCl) phthalocyanine chlorides on human lung adenocarcinoma cells (A549). Experimentally, 2 × 10(4)cells/ml were seeded in 24-well tissue culture plates and allowed to attach overnight, after which cells were treated with different concentrations of GaPcCl, InPcCl and FePcCl ranging from 2 μg/ml to 100 μg/ml. After 2h, cells were irradiated with constant light doses of 2.5 J/cm(2), 4.5 J/cm(2) and 8.5 J/cm(2) delivered from a diode laser (λ = 661 nm). Post-irradiated cells were incubated for 24h before cell viability was measured using the MTT Assay. At 24h after PDT, irradiation with a light dose of 2.5 J/cm(2) for each photosensitizing concentration of GaPcCl, InPcCl and FePcCl produced a significant decrease in cell viability, but when the treatment light dose was further increased to 4.5 J/cm(2) and 8.5 J/cm(2) the cell survival was less than 40%. Results also showed that photoactivated FePcCl decreased cell survival of A549 cells to 0% with photosensitizing concentrations of 40 μg/ml and treatment light dose of 2.5 J/cm(2). A 20 μg/ml photosensitizing concentration of FePcCl in combination with an increased treatment light dose of either 4.5 J/cm(2) or 8.5 J/cm(2) also resulted in 0% cell survival. This PDT study concludes that low concentrations on GaPcCl, InPcCl and FePcCl activated with low level light doses can be used for the effective in

  18. A thermalization energy analysis of the threshold voltage shift in amorphous indium gallium zinc oxide thin film transistors under positive gate bias stress

    NASA Astrophysics Data System (ADS)

    Niang, K. M.; Barquinha, P. M. C.; Martins, R. F. P.; Cobb, B.; Powell, M. J.; Flewitt, A. J.

    2016-02-01

    Thin film transistors (TFTs) employing an amorphous indium gallium zinc oxide (a-IGZO) channel layer exhibit a positive shift in the threshold voltage under the application of positive gate bias stress (PBS). The time and temperature dependence of the threshold voltage shift was measured and analysed using the thermalization energy concept. The peak energy barrier to defect conversion is extracted to be 0.75 eV and the attempt-to-escape frequency is extracted to be 107 s-1. These values are in remarkable agreement with measurements in a-IGZO TFTs under negative gate bias illumination stress (NBIS) reported recently (Flewitt and Powell, J. Appl. Phys. 115, 134501 (2014)). This suggests that the same physical process is responsible for both PBS and NBIS, and supports the oxygen vacancy defect migration model that the authors have previously proposed.

  19. Highest transmittance and high-mobility amorphous indium gallium zinc oxide films on flexible substrate by room-temperature deposition and post-deposition anneals

    SciTech Connect

    Gadre, Mandar J.; Alford, T. L.

    2011-08-01

    Amorphous indium gallium zinc oxide (a-IGZO) thin films of the highest transmittance reported in literature were initially deposited onto flexible polymer substrates at room temperature. The films were annealed in vacuum, air, and oxygen to enhance their electrical and optical performances. Electrical and optical characterizations were done before and after anneals. A partial reversal of the degradation in electrical properties upon annealing in oxygen was achieved by subjecting the films to subsequent vacuum anneals. A model was developed based on film texture and structural defects which showed close agreement between the measured and calculated carrier mobility values at low carrier concentrations (2-6 x 10{sup 19} cm{sup -3}).

  20. Effect of Al2O3 insulator thickness on the structural integrity of amorphous indium-gallium-zinc-oxide based thin film transistors.

    PubMed

    Kim, Hak-Jun; Hwang, In-Ju; Kim, Youn-Jea

    2014-12-01

    The current transparent oxide semiconductors (TOSs) technology provides flexibility and high performance. In this study, multi-stack nano-layers of TOSs were designed for three-dimensional analysis of amorphous indium-gallium-zinc-oxide (a-IGZO) based thin film transistors (TFTs). In particular, the effects of torsional and compressive stresses on the nano-sized active layers such as the a-IGZO layer were investigated. Numerical simulations were carried out to investigate the structural integrity of a-IGZO based TFTs with three different thicknesses of the aluminum oxide (Al2O3) insulator (δ = 10, 20, and 30 nm), respectively, using a commercial code, COMSOL Multiphysics. The results are graphically depicted for operating conditions. PMID:25971080

  1. Scaling characteristics of depletion type, fully transparent amorphous indium-gallium-zinc-oxide thin-film transistors and inverters following Ar plasma treatment

    NASA Astrophysics Data System (ADS)

    Kim, Joonwoo; Jeong, Soon Moon; Jeong, Jaewook

    2015-11-01

    We fabricated depletion type, transparent amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) and inverters with an Ar plasma treatment and analyzed their scaling characteristics with channel lengths ranging from 2 to 100 µm. The improvement of the field-effect mobility of a-IGZO TFTs is apparent only for short channel lengths. There is also an unexpected side effect of the Ar plasma treatment, which introduces back-channel interfacial states and induces a positive shift in the threshold voltage of a-IGZO TFTs. The resulting increase in the field-effect mobility and the positive shift in the threshold voltage of each TFT increase the differential gain up to 3 times and the positive shift in the transient point of the transparent inverters.

  2. Realization of write-once-read-many-times memory device with O{sub 2} plasma-treated indium gallium zinc oxide thin film

    SciTech Connect

    Liu, P. Chen, T. P. Li, X. D.; Wong, J. I.; Liu, Z.; Liu, Y.; Leong, K. C.

    2014-01-20

    A write-once-read-many-times (WORM) memory devices based on O{sub 2} plasma-treated indium gallium zinc oxide (IGZO) thin films has been demonstrated. The device has a simple Al/IGZO/Al structure. The device has a normally OFF state with a very high resistance (e.g., the resistance at 2 V is ∼10{sup 9} Ω for a device with the radius of 50 μm) as a result of the O{sub 2} plasma treatment on the IGZO thin films. The device could be switched to an ON state with a low resistance (e.g., the resistance at 2 V is ∼10{sup 3} Ω for the radius of 50 μm) by applying a voltage pulse (e.g., 10 V/1 μs). The WORM device has good data-retention and reading-endurance capabilities.

  3. Effects of low-temperature (120 °C) annealing on the carrier concentration and trap density in amorphous indium gallium zinc oxide thin film transistors

    SciTech Connect

    Kim, Jae-sung; Piao, Mingxing; Jang, Ho-Kyun; Kim, Gyu-Tae; Oh, Byung Su; Joo, Min-Kyu; Ahn, Seung-Eon

    2014-12-28

    We report an investigation of the effects of low-temperature annealing on the electrical properties of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). X-ray photoelectron spectroscopy was used to characterize the charge carrier concentration, which is related to the density of oxygen vacancies. The field-effect mobility was found to decrease as a function of the charge carrier concentration, owing to the presence of band-tail states. By employing the transmission line method, we show that the contact resistance did not significantly contribute to the changes in device performance after annealing. In addition, using low-frequency noise analyses, we found that the trap density decreased by a factor of 10 following annealing at 120 °C. The switching operation and on/off ratio of the a-IGZO TFTs improved considerably after low-temperature annealing.

  4. Alumina nanoparticle/polymer nanocomposite dielectric for flexible amorphous indium-gallium-zinc oxide thin film transistors on plastic substrate with superior stability

    SciTech Connect

    Lai, Hsin-Cheng; Pei, Zingway; Jian, Jyun-Ruri; Tzeng, Bo-Jie

    2014-07-21

    In this study, the Al{sub 2}O{sub 3} nanoparticles were incorporated into polymer as a nono-composite dielectric for used in a flexible amorphous Indium-Gallium-Zinc Oxide (a-IGZO) thin-film transistor (TFT) on a polyethylene naphthalate substrate by solution process. The process temperature was well below 100 °C. The a-IGZO TFT exhibit a mobility of 5.13 cm{sup 2}/V s on the flexible substrate. After bending at a radius of 4 mm (strain = 1.56%) for more than 100 times, the performance of this a-IGZO TFT was nearly unchanged. In addition, the electrical characteristics are less altered after positive gate bias stress at 10 V for 1500 s. Thus, this technology is suitable for use in flexible displays.

  5. A transparent diode with high rectifying ratio using amorphous indium-gallium-zinc oxide/SiN{sub x} coupled junction

    SciTech Connect

    Choi, Myung-Jea; Kim, Myeong-Ho; Choi, Duck-Kyun

    2015-08-03

    We introduce a transparent diode that shows both high rectifying ratio and low leakage current at process temperature below 250 °C. This device is clearly distinguished from all previous transparent diodes in that the rectifying behavior results from the junction between a semiconductor (amorphous indium-gallium-zinc oxide (a-IGZO)) and insulator (SiN{sub x}). We systematically study the properties of each junction within the device structure and demonstrate that the a-IGZO/SiN{sub x} junction is the source of the outstanding rectification. The electrical characteristics of this transparent diode are: 2.8 A/cm{sup 2} on-current density measured at −7 V; lower than 7.3 × 10{sup −9} A/cm{sup 2} off-current density; 2.53 ideality factor; and high rectifying ratio of 10{sup 8}–10{sup 9}. Furthermore, the diode structure has a transmittance of over 80% across the visible light range. The operating principle of the indium-tin oxide (ITO)/a-IGZO/SiN{sub x}/ITO device was examined with an aid of the energy band diagram and we propose a preliminary model for the rectifying behavior. Finally, we suggest further directions for research on this transparent diode.

  6. Indium and gallium diffusion through zirconia in the TiN/ZrO{sub 2}/InGaAs stack

    SciTech Connect

    Ceballos-Sanchez, O.; Martinez, E.; Guedj, C.; Veillerot, M.; Herrera-Gomez, A.

    2015-06-01

    Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) was applied to the TiN/ZrO{sub 2}/InGaAs stack to assess its thermal stability. Through a robust ARXPS analysis, it was possible to observe subtle effects such as the thermally induced diffusion of substrate atomic species (In and Ga) through the dielectric layer. The detailed characterization of the film structure allowed for assessing the depth profiles of the diffused atomic species by means of the scenarios-method. Since the quantification for the amount of diffused material was done at different temperatures, it was possible to obtain an approximate value of the activation energy for the diffusion of indium through zirconia. The result is very similar to the previously reported values for indium diffusion through alumina and through hafnia.

  7. Electrophysical properties of gallium arsenide in combination with impurity-doped germanium and isovalent indium and antimony impurities

    SciTech Connect

    Krivov, M.A.; Malisova, E.V.; Nikiforova, M.P.; Starikov, A.N.; Khludkov, S.S.; Grigor'ev, Yu.A.; Egorova, O.L.; Osvenskii, V.B.

    1988-03-01

    The temperature dependence of the charge carrier concentration and mobility in n-type GaAs monocrystals doped jointly by Ge and isovalent In and Sb impurities is investigated. The observable charge carrier concentration and mobility changes in the GaAs:Ge:In and GaAs:Ge:Sb are compared with the corresponding characteristics in GaAs:Ge, and the change in properties along the ingots can be explained by the Ge impurity redistribution in the gallium and arsenic sublattices in the presence of an isovalent impurity.

  8. Improving source/drain contact resistance of amorphous indium-gallium-zinc-oxide thin-film transistors using an n+-ZnO buffer layer

    NASA Astrophysics Data System (ADS)

    Hung, Chien-Hsiung; Wang, Shui-Jinn; Lin, Chieh; Wu, Chien-Hung; Chen, Yen-Han; Liu, Pang-Yi; Tu, Yung-Chun; Lin, Tseng-Hsing

    2016-06-01

    To avoid high temperature annealing in improving the source/drain (S/D) resistance (R DS) of amorphous indium-gallium-zinc-oxide (α-IGZO) thin-film transistors (TFTs) for flexible electronics, a simple and efficient technique using a sputtering-deposited n+-ZnO buffer layer (BL) sandwiched between the S/D electrode and the α-IGZO channel is proposed and demonstrated. It shows that the R DS of α-IGZO TFTs with the proposed n+-ZnO BL is reduced to 8.1 × 103 Ω as compared with 6.1 × 104 Ω of the conventional one. The facilitation of carrier tunneling between the S/D electrode and the α-IGZO channel through the use of the n+-ZnO BL to lower the effective barrier height therein is responsible for the R DS reduction. Effects of the chamber pressure on the carrier concentration of the sputtering-deposited n+-ZnO BL and the thickness of the BL on the degree of improvement in the performance of α-IGZO TFTs are analyzed and discussed.

  9. High-pressure Gas Activation for Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistors at 100 °C

    NASA Astrophysics Data System (ADS)

    Kim, Won-Gi; Tak, Young Jun; Du Ahn, Byung; Jung, Tae Soo; Chung, Kwun-Bum; Kim, Hyun Jae

    2016-03-01

    We investigated the use of high-pressure gases as an activation energy source for amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs). High-pressure annealing (HPA) in nitrogen (N2) and oxygen (O2) gases was applied to activate a-IGZO TFTs at 100 °C at pressures in the range from 0.5 to 4 MPa. Activation of the a-IGZO TFTs during HPA is attributed to the effect of the high-pressure environment, so that the activation energy is supplied from the kinetic energy of the gas molecules. We reduced the activation temperature from 300 °C to 100 °C via the use of HPA. The electrical characteristics of a-IGZO TFTs annealed in O2 at 2 MPa were superior to those annealed in N2 at 4 MPa, despite the lower pressure. For O2 HPA under 2 MPa at 100 °C, the field effect mobility and the threshold voltage shift under positive bias stress were improved by 9.00 to 10.58 cm2/V.s and 3.89 to 2.64 V, respectively. This is attributed to not only the effects of the pressurizing effect but also the metal-oxide construction effect which assists to facilitate the formation of channel layer and reduces oxygen vacancies, served as electron trap sites.

  10. Indium and gallium oxynitrides prepared in the presence of Zn{sup 2+} by ammonolysis of the oxide precursors obtained via the citrate route

    SciTech Connect

    Miyaake, Azumi; Masubuchi, Yuji; Takeda, Takashi; Kikkawa, Shinichi

    2010-04-15

    Ammonia nitridation of indium and gallium oxide precursors obtained through a soft solution route led to their oxynitrides [In{sub 0.97}{open_square}{sub 0.03}][N{sub 0.92}O{sub 0.08}] at 660 {sup o}C and [Ga{sub 0.89}{open_square}{sub 0.11}][N{sub 0.66}O{sub 0.34}] at 850 {sup o}C, respectively, where {open_square} refers to a In or Ga vacancy. Cation vacancies in their wurtzite-type lattice were eliminated in similar preparations with the co-presence of Zn{sup 2+} by forming complete solid solutions of (InN){sub 1-x}(ZnO){sub x} and (GaN){sub 1-y}(ZnO){sub y}. The optical absorption edge shape was found to be relatively steep at the solid solution limits of x {approx} 0.23 and y {approx} 0.33 compared to the case without zinc.

  11. Improvement in reliability of amorphous indium-gallium-zinc oxide thin-film transistors with Teflon/SiO2 bilayer passivation under gate bias stress

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Tseng, Fan-Ping; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der; Huang, Bohr-Ran

    2016-02-01

    The reliability of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with Teflon/SiO2 bilayer passivation prepared under positive and negative gate bias stresses (PGBS and NGBS, respectively) was investigated. Heavier electrical degradation was observed under PGBS than under NGBS, indicating that the environmental effects under PGBS are more evident than those under NGBS. The device with bilayer passivation under PGBS shows two-step degradation. The positive threshold voltage shifts during the initial stressing period (before 500 s), owing to the charges trapped in the gate insulator or at the gate insulator/a-IGZO active layer interface. The negative threshold voltage shift accompanies the increase in subthreshold swing (SS) for the continuous stressing period (after 500 s) owing to H2O molecules from ambience diffused within the a-IGZO TFTs. It is believed that Teflon/SiO2 bilayer passivation can effectively improve the reliability of the a-IGZO TFTs without passivation even though the devices are stressed under gate bias.

  12. Indium-gallium-zinc-oxide layer used to increase light transmittance efficiency of adhesive layer for stacked-type multijunction solar cells

    NASA Astrophysics Data System (ADS)

    Yoshidomi, Shinya; Kimura, Shunsuke; Hasumi, Masahiko; Sameshima, Toshiyuki

    2015-11-01

    We report the increase in transmittance efficiency of the intermediate layer for multijunction solar cells caused by the indium-gallium-zinc-oxide (IGZO) layer used as the antireflection layer. Si substrates coated with a 200-nm-thick IGZO layer with a refractive index of 1.85 were prepared. The resistivity of the IGZO layer was increased from 0.0069 (as-deposited) to 0.032 Ω cm by heat treatment at 350 °C for 1 h to prevent free-carrier optical absorption. Samples with the Si/IGZO/adhesive/IGZO/Si structure were fabricated. The average transmissivity for wavelengths between 1200 and 1600 nm was 49%, which was close to 55% of single-crystal silicon substrates. A high effective transmittance efficiency of 89% was experimentally achieved. The numerical calculation showed in an effective transmittance efficiency of 99% for 170-nm-thick antireflection layers with a resistivity of 0.6 Ω cm and a refractive index of 2.1.

  13. Effect of top gate bias on photocurrent and negative bias illumination stress instability in dual gate amorphous indium-gallium-zinc oxide thin-film transistor

    NASA Astrophysics Data System (ADS)

    Lee, Eunji; Chowdhury, Md Delwar Hossain; Park, Min Sang; Jang, Jin

    2015-12-01

    We have studied the effect of top gate bias (VTG) on the generation of photocurrent and the decay of photocurrent for back channel etched inverted staggered dual gate structure amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Upon 5 min of exposure of 365 nm wavelength and 0.7 mW/cm2 intensity light with negative bottom gate bias, the maximum photocurrent increases from 3.29 to 322 pA with increasing the VTG from -15 to +15 V. By changing VTG from negative to positive, the Fermi level (EF) shifts toward conduction band edge (EC), which substantially controls the conversion of neutral vacancy to charged one (VO → VO+/VO2+ + e-/2e-), peroxide (O22-) formation or conversion of ionized interstitial (Oi2-) to neutral interstitial (Oi), thus electron concentration at conduction band. With increasing the exposure time, more carriers are generated, and thus, maximum photocurrent increases until being saturated. After negative bias illumination stress, the transfer curve shows -2.7 V shift at VTG = -15 V, which gradually decreases to -0.42 V shift at VTG = +15 V. It clearly reveals that the position of electron quasi-Fermi level controls the formation of donor defects (VO+/VO2+/O22-/Oi) and/or hole trapping in the a-IGZO /interfaces.

  14. Effect of top gate potential on bias-stress for dual gate amorphous indium-gallium-zinc-oxide thin film transistor

    NASA Astrophysics Data System (ADS)

    Chun, Minkyu; Um, Jae Gwang; Park, Min Sang; Chowdhury, Md Delwar Hossain; Jang, Jin

    2016-07-01

    We report the abnormal behavior of the threshold voltage (VTH) shift under positive bias Temperature stress (PBTS) and negative bias temperature stress (NBTS) at top/bottom gate in dual gate amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). It is found that the PBTS at top gate shows negative transfer shift and NBTS shows positive transfer shift for both top and bottom gate sweep. The shift of bottom/top gate sweep is dominated by top gate bias (VTG), while bottom gate bias (VBG) is less effect than VTG. The X-ray photoelectron spectroscopy (XPS) depth profile provides the evidence of In metal diffusion to the top SiO2/a-IGZO and also the existence of large amount of In+ under positive top gate bias around top interfaces, thus negative transfer shift is observed. On the other hand, the formation of OH- at top interfaces under the stress of negative top gate bias shows negative transfer shift. The domination of VTG both on bottom/top gate sweep after PBTS/NBTS is obviously occurred due to thin active layer.

  15. Reduction of defect formation in amorphous indium-gallium-zinc-oxide thin film transistors by N{sub 2}O plasma treatment

    SciTech Connect

    Jhu, Jhe-Ciou; Chang, Ting-Chang; Chang, Geng-Wei; Tai, Ya-Hsiang; Tsai, Wu-Wei; Chiang, Wen-Jen; Yan, Jing-Yi

    2013-11-28

    An abnormal sub-threshold leakage current is observed at high temperature in amorphous indium-gallium-zinc-oxide thin film transistors (a-IGZO TFTs). This phenomenon occurs due to a reduced number of defects in the device's a-IGZO active layer after the device has undergone N{sub 2}O plasma treatment. Experimental verification shows that the N{sub 2}O plasma treatment enhances the thin film bonding strength, thereby suppressing the formation of temperature-dependent holes, which are generated above 400 K by oxygen atoms leaving their original sites. The N{sub 2}O plasma treatment devices have better stability performance than as-fabricated devices. The results suggest that the density of defects for a-IGZO TFTs with N{sub 2}O plasma treatment is much lower than that in as-fabricated devices. The N{sub 2}O plasma treatment repairs the defects and suppresses temperature-dependent sub-threshold leakage current.

  16. Indium-chlorine and gallium-chlorine tetrasubstituted phthalocyanines in a bulk system, Langmuir monolayers and Langmuir-Blodgett nanolayers--spectroscopic investigations.

    PubMed

    Bursa, B; Wróbel, D; Biadasz, A; Kędzierski, K; Lewandowska, K; Graja, A; Szybowicz, M; Durmuş, M

    2014-07-15

    The paper deals with spectroscopic characterization of metallic phthalocyanines (Pc's) (indium and gallium) complexed with chlorine and substituted with four benzyloxyphenoxy peripheral groups in bulk systems, 2D Langmuir monolayers and Langmuir-Blodgett nanolayers. An influence of the molecular structure of dyes (the presence of metal and of substitutes attached to the phthalocyanine macroring) on the in situ measurements of light absorption is reported. Molecular arrangement of the phthalocyanine molecular skeleton in the Langmuir monolayers on water substrate and in the Langmuir-Blodgett nanolayers is evaluated. A comparison of the light absorption spectra of the phthalocyanine monolayers with the spectra of the dyes in solution supports the existence of dye aggregates in the monolayer. It was shown that the type of dye aggregates (oblique and H types) depends markedly on the dye molecular structures. The NIR-IR, IR reflection-absorption and Raman spectra are also monitored for Langmuir-Blodgett nanolayers in non-polarized and polarized light. It was shown that the dye molecules in the Langmuir-Blodgett layers are oriented nearly vertically with respect to a gold substrate.

  17. State retention flip flop architectures with different tradeoffs using crystalline indium gallium zinc oxide transistors implemented in a 32-bit normally-off microprocessor

    NASA Astrophysics Data System (ADS)

    Sjökvist, Niclas; Ohmaru, Takuro; Isobe, Atsuo; Tsutsui, Naoaki; Tamura, Hikaru; Uesugi, Wataru; Ishizu, Takahiko; Onuki, Tatsuya; Ohshima, Kazuaki; Matsuzaki, Takanori; Mimura, Hidetoshi; Hirose, Atsushi; Suzuki, Yasutaka; Ieda, Yoshinori; Atsumi, Tomoaki; Shionoiri, Yutaka; Kato, Kiyoshi; Goto, Gensuke; Koyama, Jun; Fujita, Masahiro; Yamazaki, Shunpei

    2014-01-01

    As leakage power continues to increase when transistor sizes are downscaled, it becomes increasingly hard to achieve low power consumption in modern chips. Normally-off processors use state-retention and non-volatile circuits to make power gating more efficient with less static power. In this paper, we propose two novel state-retention flip-flop designs based on a parallel and series retention circuit architectures utilizing crystalline indium gallium zinc oxide transistors, which can achieve state retention with zero static power. To demonstrate the application of these different designs, they are implemented in a 32-bit normally-off microprocessor with an energy break-even time of 1.47 µs for the parallel type design and 0.93 µs for the series type design, at a clock frequency of 15 MHz. We show that decreasing the power supply duty cycle to 0.9%, the average current of the processor core can be decreased by over 99% using either type of flip-flop.

  18. Properties of c-axis-aligned crystalline indium-gallium-zinc oxide field-effect transistors fabricated through a tapered-trench gate process

    NASA Astrophysics Data System (ADS)

    Asami, Yoshinobu; Kurata, Motomu; Okazaki, Yutaka; Higa, Eiji; Matsubayashi, Daisuke; Okamoto, Satoru; Sasagawa, Shinya; Moriwaka, Tomoaki; Kakehata, Tetsuya; Yakubo, Yuto; Kato, Kiyoshi; Hamada, Takashi; Sakakura, Masayuki; Hayakawa, Masahiko; Yamazaki, Shunpei

    2016-04-01

    To achieve both low power consumption and high-speed operation, we fabricated c-axis-aligned crystalline indium-gallium-zinc oxide (CAAC-IGZO) field-effect transistors (FETs) with In-rich IGZO and common IGZO (\\text{In}:\\text{Ga}:\\text{Zn} = 1:1:1 in atomic ratio) active layers through a simple process using trench gates, and evaluated their characteristics. The results confirm that 60-nm-node IGZO FETs fabricated through a 450 °C process show an extremely low off-state current below the detection limit (at most 2 × 10-16 A) even at a measurement temperature of 150 °C. The results also reveal that the FETs with the In-rich IGZO active layer show a higher on-state current than those with the common IGZO active layer and have excellent frequency characteristics with a cutoff frequency and a maximum oscillation frequency of up to 20 and 6 GHz, respectively. Thus, we demonstrated that CAAC-IGZO FETs with trench gates are promising for achieving both low power consumption and high-speed operation.

  19. A normally-off microcontroller unit with an 85% power overhead reduction based on crystalline indium gallium zinc oxide field effect transistors

    NASA Astrophysics Data System (ADS)

    Ohshima, Kazuaki; Kobayashi, Hidetomo; Nishijima, Tatsuji; Yoneda, Seiichi; Tomatsu, Hiroyuki; Maeda, Shuhei; Tsukida, Kazuki; Takahashi, Kei; Sato, Takehisa; Watanabe, Kazunori; Yamamoto, Ro; Kozuma, Munehiro; Aoki, Takeshi; Yamade, Naoto; Ieda, Yoshinori; Miyairi, Hidekazu; Atsumi, Tomoaki; Shionoiri, Yutaka; Kato, Kiyoshi; Maehashi, Yukio; Koyama, Jun; Yamazaki, Shunpei

    2014-01-01

    A low-power normally-off microcontroller unit (NMCU) having state-retention flip-flops (SRFFs) using a c-axis aligned crystalline oxide semiconductor (CAAC-OS) such as indium gallium zinc oxide (IGZO) transistors and employing a distributed backup and recovery method (distributed method) is fabricated. Compared to an NMCU employing a centralized backup and recovery method (centralized method), the NMCU employing the distributed method can be powered off approximately 75 µs earlier after main processing and can start the main processing approximately 75 µs earlier after power-on. The NMCU employing the distributed method can reduce power overhead by approximately 85% and power consumption by approximately 18% compared to the NMCU employing the centralized method. The NMCU employing the distributed method can retain data even when it is powered off, can back up data at high speed, and can start effective processing immediately after power-on. The NMCU could be applied to a low-power MCU.

  20. Meyer-Neldel Rule and Extraction of Density of States in Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistor by Considering Surface Band Bending

    NASA Astrophysics Data System (ADS)

    Jeong, Jaewook; Kyeong Jeong, Jae; Park, Jin-Seong; Mo, Yeon-Gon; Hong, Yongtaek

    2010-03-01

    In this study, we analyzed the temperature-dependent characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). We observed that a-IGZO TFTs obey the Meyer-Neldel rule (MN rule) at low gate-to-source voltage (VGS) and the inverse MN rule at high VGS, both of which can be explained by the statistical shift of Fermi level and electrostatic potential. Large Fermi level movement for small VGS change and the inverse MN rule, which are hardly observed for conventional amorphous TFTs, indicate that there is a very low density of state (DOS) in the sub-bandgap region for a-IGZO TFTs and the performance of TFTs is not affected by contact characteristics, respectively. By using the field-effect method and considering surface band bending, we extracted the DOS in the sub-bandgap region, the distribution of which is clearly distinguished by deep and tail states. The calculated parameters for tail and deep states were Nta = 3.5 ×1017 cm-3 eV-1, Eta = 0.18 eV, Nda = 1.6×1016 cm-3 eV-1, and σda = 0.21 eV.

  1. Study of Novel Floating-Gate Oxide Semiconductor Memory Using Indium-Gallium-Zinc Oxide for Low-Power System-on-Panel Applications

    NASA Astrophysics Data System (ADS)

    Yamauchi, Yoshimitsu; Kamakura, Yoshinari; Isagi, Yousuke; Matsuoka, Toshimasa; Malotaux, Satoshi

    2013-09-01

    A novel floating-gate oxide semiconductor (FLOTOS) memory using a wide-band-gap indium-gallium-zinc oxide (IGZO) is presented for low-power system-on-panel applications. An IGZO thin-film-transistor (TFT) is used as a memory transistor for controlling read current as well as a switching transistor for storing charges in a storage capacitor (Cs). The FLOTOS memory is fabricated using a standard IGZO TFT process without any additional process or mask steps. The proposed precharge-assisted threshold voltage compensation technique makes it possible to realize an infinite number of write cycles and a low-power write operation with a bit-line voltage of 5 V. Furthermore, excellent data retention longer than 10 h is obtained at 60 °C even under the worst bias-stress condition of read operation with the ultra low off-state leakage (2.8×10-20 A/µm) of the IGZO TFTs, which is estimated to be smaller by more than 7 orders of magnitude than that of polycrystalline silicon TFTs.

  2. The SAM, not the electrodes, dominates charge transport in metal-monolayer//Ga2O3/gallium-indium eutectic junctions.

    PubMed

    Reus, William F; Thuo, Martin M; Shapiro, Nathan D; Nijhuis, Christian A; Whitesides, George M

    2012-06-26

    The liquid-metal eutectic of gallium and indium (EGaIn) is a useful electrode for making soft electrical contacts to self-assembled monolayers (SAMs). This electrode has, however, one feature whose effect on charge transport has been incompletely understood: a thin (approximately 0.7 nm) film-consisting primarily of Ga(2)O(3)-that covers its surface when in contact with air. SAMs that rectify current have been measured using this electrode in Ag(TS)-SAM//Ga(2)O(3)/EGaIn (where Ag(TS) = template-stripped Ag surface) junctions. This paper organizes evidence, both published and unpublished, showing that the molecular structure of the SAM (specifically, the presence of an accessible molecular orbital asymmetrically located within the SAM), not the difference between the electrodes or the characteristics of the Ga(2)O(3) film, causes the observed rectification. By examining and ruling out potential mechanisms of rectification that rely either on the Ga(2)O(3) film or on the asymmetry of the electrodes, this paper demonstrates that the structure of the SAM dominates charge transport through Ag(TS)-SAM//Ga(2)O(3)/EGaIn junctions, and that the electrical characteristics of the Ga(2)O(3) film have a negligible effect on these measurements.

  3. Indium-chlorine and gallium-chlorine tetrasubstituted phthalocyanines in a bulk system, Langmuir monolayers and Langmuir-Blodgett nanolayers--spectroscopic investigations.

    PubMed

    Bursa, B; Wróbel, D; Biadasz, A; Kędzierski, K; Lewandowska, K; Graja, A; Szybowicz, M; Durmuş, M

    2014-07-15

    The paper deals with spectroscopic characterization of metallic phthalocyanines (Pc's) (indium and gallium) complexed with chlorine and substituted with four benzyloxyphenoxy peripheral groups in bulk systems, 2D Langmuir monolayers and Langmuir-Blodgett nanolayers. An influence of the molecular structure of dyes (the presence of metal and of substitutes attached to the phthalocyanine macroring) on the in situ measurements of light absorption is reported. Molecular arrangement of the phthalocyanine molecular skeleton in the Langmuir monolayers on water substrate and in the Langmuir-Blodgett nanolayers is evaluated. A comparison of the light absorption spectra of the phthalocyanine monolayers with the spectra of the dyes in solution supports the existence of dye aggregates in the monolayer. It was shown that the type of dye aggregates (oblique and H types) depends markedly on the dye molecular structures. The NIR-IR, IR reflection-absorption and Raman spectra are also monitored for Langmuir-Blodgett nanolayers in non-polarized and polarized light. It was shown that the dye molecules in the Langmuir-Blodgett layers are oriented nearly vertically with respect to a gold substrate. PMID:24682066

  4. Fabrication of conducting-filament-embedded indium tin oxide electrodes: application to lateral-type gallium nitride light-emitting diodes.

    PubMed

    Kim, Hee-Dong; Kim, Kyeong Heon; Kim, Su Jin; Kim, Tae Geun

    2015-11-01

    A novel conducting filament (CF)-embedded indium tin oxide (ITO) film is fabricated using an electrical breakdown method. To assess the performance of this layer as an ohmic contact, it is applied to GaN (gallium nitride) light-emitting diodes (LEDs) as a p-type electrode for comparison with typical GaN LEDs using metallic ITO. The operating voltage and output power of the LED with the CF embedded ITO are 3.93 V and 8.49 mW, respectively, at an injection current of 100 mA. This is comparable to the operating voltage and output power of the conventionally fabricated LEDs using metallic ITO (3.93 V and 8.43 mW). Moreover, the CF-ITO LED displays uniform and bright light emission indicating excellent current injection and spreading. These results suggest that the proposed method of forming ohmic contacts is at least as effective as the conventional method. PMID:26561146

  5. Acoustic and NMR investigations of melting and crystallization of indium-gallium alloys in pores of synthetic opal matrices

    NASA Astrophysics Data System (ADS)

    Pirozerskii, A. L.; Charnaya, E. V.; Lee, M. K.; Chang, L. J.; Nedbai, A. I.; Kumzerov, Yu. A.; Fokin, A. V.; Samoilovich, M. I.; Lebedeva, E. L.; Bugaev, A. S.

    2016-05-01

    The paper presents the results of studying the crystallization and melting processes of Ga-In eutectic alloys, which are embedded in opal matrices, using acoustic and NMR methods. The indium concentrations in the alloys were 4, 6, 9, and 15 at %. Measurements were performed upon cooling from room temperature to complete crystallization of the alloys and subsequent heating. It is revealed how the size effects and alloy composition influence the formation of phases with α- and β-Ga structures and on changes in the melting-temperature ranges. A difference was observed between the results obtained using acoustic and NMR methods, which was attributed to different temperature measurement conditions.

  6. Growth of 1.5 micron gallium indium nitrogen arsenic antimonide vertical cavity surface emitting lasers by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Wistey, Mark Allan

    Fiber optics has revolutionized long distance communication and long haul networks, allowing unimaginable data speeds and noise-free telephone calls around the world for mere pennies per hour at the trunk level. But the high speeds of optical fiber generally do not extend to individual workstations or to the home, in large part because it has been difficult and expensive to produce lasers which emitted light at wavelengths which could take advantage of optical fiber. One of the most promising solutions to this problem is the development of a new class of semiconductors known as dilute nitrides. Dilute nitrides such as GaInNAs can be grown directly on gallium arsenide, which allows well-established processing techniques. More important, gallium arsenide allows the growth of vertical-cavity surface-emitting lasers (VCSELs), which can be grown in dense, 2D arrays on each wafer, providing tremendous economies of scale for manufacturing, testing, and packaging. Unfortunately, GaInNAs lasers have suffered from what has been dubbed the "nitrogen penalty," with high thresholds and low efficiency as the fraction of nitrogen in the semiconductor was increased. This thesis describes the steps taken to identify and essentially eliminate the nitrogen penalty. Protecting the wafer surface from plasma ignition, using an arsenic cap, greatly improved material quality. Using a Langmuir probe, we further found that the nitrogen plasma source produced a large number of ions which damaged the wafer during growth. The ions were dramatically reduced using deflection plates. Low voltage deflection plates were found to be preferable to high voltages, and simulations showed low voltages to be adequate for ion removal. The long wavelengths from dilute nitrides can be partly explained by wafer damage during growth. As a result of these studies, we demonstrated the first CW, room temperature lasers at wavelengths beyond 1.5mum on gallium arsenide, and the first GaInNAs(Sb) VCSELs beyond 1

  7. High precision radiometry using an indium arsenide/indium gallium arsenide quantum dot-in-a-well infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Andrews, Jonathan R.

    Sensitivity, noise and performance criteria were evaluated for different varieties of InAs/InGaAs quantum dots-in-a-well (DWELL) and quantum dots-in-a-double-well (double DWELL) focal plane arrays (FPAs). These characteristics were measured and compared to those measured from a commercial quantum well infrared photodetector (QWIP) in the same experimental setup to allow a side-by-side comparison of these devices with many system variables held constant. The QWIP device was expected to perform the best, due to its higher number of active regions and enhancement grating, but the performance of the other devices was unknown. The DWELL and double DWELL samples were grown by molecular beam epitaxy (MBE) and fabricated into 320 x 256 pixel FPAs with indium bumps via standard lithography at the University of New Mexico. All samples, including the 320 x 256 pixel QWIPs were hybridized to Indigo Systems Corporation ISC9705 read out integrated circuits and device performance was measured with the SE-IR Corporation CamIRa test system at part cooling of 60°K, 70°K and 80°K. The QWIP performed best at lower device cooling, but could not operate at 80°K. The DWELL device demonstrated favorable operation at 60°K, but performance at 70°K was poor and the device did not perform at 80°K. Both double DWELL devices under test performed well across all device temperatures. The mean NEDT for the DWELL was 143°mK and the two double DWELL devices were 105.7°mK and 160.6°mK at 60°K part temperature. The double DWELL devices showed the lower noise and higher responsivity at higher device temperatures. This document also reviewed methods of non-uniformity correction and suggested methods to improve performance and results by carefully choosing the method of correction and the values.

  8. Evaluation of the indium gallium nitride/silicon broken-gap heterojunction and its potential application for solar cells

    NASA Astrophysics Data System (ADS)

    Yao, Yuan

    InGaN (especially In-rich alloy) has been actively studied for decades since the band gap of InN was revised downward from ˜2.0 eV to 0.64 eV. The potential applications for alloys of In-rich InGaN hence became apparent. Despite the promising potential, photovoltaic devices based on InGaN have struggled due to a number of key limitations and fundamental physical problems. Firstly, due to the deep excursion of the InN conduction band at the gamma point, defects in InN are almost universally n-type leading to unintentional degenerate doping. This also leads to the problem of electron accumulation at all surfaces and interfaces of InN. Secondly, p-type doping is problematic, partially due to the degenerate doping effect of defects, but it has also been observed that Mg-doping, while leading to a p-type layer, dramatically reduces the quantum efficiency. This thesis explores an alternative approach using n-type InGaN to form a heterojunction with a p-type Si substrate. One potential benefit to using p-type Si as a substrate material for InGaN is that the valence band of Si possibly lines up with the conduction band of InGaN for a specific mole fraction of indium. Such a band alignment is known as a broken gap heterojunction, an example of which is the interface between InAs and AlxGa 1--xSb. The benefits of this broken-gap junction include a low series resistance, high electron mobility, and mobility only weakly dependent on temperature. These properties enable new approach to photovoltaic devices. The InGaN/Si heterojunctions were fabricated by plasma-assisted molecular beam epitaxy under stoichiometric flux conditions. An ultra-thin SiN interface layer was introduced, by Si nitridation process, to passivate the substrate surface and prevent In-Si and Ga-Si eutectic problems. InGaN films with a variety of indium mole fractions were grown by calibrating the In/Ga flux ratio during the deposition. The chemical composition of as-grown films was characterized by x

  9. Effect of top gate bias on photocurrent and negative bias illumination stress instability in dual gate amorphous indium-gallium-zinc oxide thin-film transistor

    SciTech Connect

    Lee, Eunji; Chowdhury, Md Delwar Hossain; Park, Min Sang; Jang, Jin

    2015-12-07

    We have studied the effect of top gate bias (V{sub TG}) on the generation of photocurrent and the decay of photocurrent for back channel etched inverted staggered dual gate structure amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Upon 5 min of exposure of 365 nm wavelength and 0.7 mW/cm{sup 2} intensity light with negative bottom gate bias, the maximum photocurrent increases from 3.29 to 322 pA with increasing the V{sub TG} from −15 to +15 V. By changing V{sub TG} from negative to positive, the Fermi level (E{sub F}) shifts toward conduction band edge (E{sub C}), which substantially controls the conversion of neutral vacancy to charged one (V{sub O} → V{sub O}{sup +}/V{sub O}{sup 2+} + e{sup −}/2e{sup −}), peroxide (O{sub 2}{sup 2−}) formation or conversion of ionized interstitial (O{sub i}{sup 2−}) to neutral interstitial (O{sub i}), thus electron concentration at conduction band. With increasing the exposure time, more carriers are generated, and thus, maximum photocurrent increases until being saturated. After negative bias illumination stress, the transfer curve shows −2.7 V shift at V{sub TG} = −15 V, which gradually decreases to −0.42 V shift at V{sub TG} = +15 V. It clearly reveals that the position of electron quasi-Fermi level controls the formation of donor defects (V{sub O}{sup +}/V{sub O}{sup 2+}/O{sub 2}{sup 2−}/O{sub i}) and/or hole trapping in the a-IGZO /interfaces.

  10. Comparative study of the toxic effects of gallium arsenide, indium arsenide and arsenic trioxide following intratracheal instillations to the lung of Syrian golden hamsters.

    PubMed

    Tanaka, A; Hirata, M; Omura, M; Zhao, M; Makita, Y; Yamazaki, K; Inoue, N; Gotoh, K

    2000-01-01

    Toxic effects of gallium arsenide (GaAs), indium arsenide (InAs) and arsenic trioxide (As2O3) were studied in male Syrian golden hamsters. GaAs (7.7 mg/kg) and As2O3 (1.3 mg/kg) particles were instilled intratracheally twice a week a total of 16 times, while InAs (7.7 mg/kg) was instilled a total of 14 times. As a control, hamsters were treated with the vehicle, phosphate buffer solution. During the instillation period, the cumulative body weight gain of the InAs-, but not the GaAs- or As2O3-treated hamsters was suppressed significantly, when compared with the control group. Slight to severe inflammatory responses were observed in the lung for all treatment groups. The most severe inflammatory change, characterized by an accumulation of neutrophils and macrophages, exudation, thickness of the pleura and fibrotic proliferation was found in the InAs-treated hamsters. Extensive alveolar or bronchiolar cell hyperplasia with or without keratinizing squamous cell metaplasia was observed in almost all the InAs-treated hamsters. Furthermore, squamous cell metaplasia or squamous cell hyperplasia developed in some of the InAs-treated hamsters, but not in the GaAs- or As2O3-treated hamsters. Slight to mild lesions were found in the convoluted tubules of the kidney in both the GaAs and InAs groups. From the present study, the toxic potency of these particles was provisionally estimated to be in the following order: InAs > GaAs > As2O3, at the dosage level used in this study. Furthermore, there was evidence that InAs particles could induce pulmonary, renal or systemic toxicity, and as such, InAs particles may produce pulmonary precancerous change when instilled intratracheally into hamsters.

  11. High-pressure Gas Activation for Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistors at 100 °C.

    PubMed

    Kim, Won-Gi; Tak, Young Jun; Du Ahn, Byung; Jung, Tae Soo; Chung, Kwun-Bum; Kim, Hyun Jae

    2016-01-01

    We investigated the use of high-pressure gases as an activation energy source for amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs). High-pressure annealing (HPA) in nitrogen (N2) and oxygen (O2) gases was applied to activate a-IGZO TFTs at 100 °C at pressures in the range from 0.5 to 4 MPa. Activation of the a-IGZO TFTs during HPA is attributed to the effect of the high-pressure environment, so that the activation energy is supplied from the kinetic energy of the gas molecules. We reduced the activation temperature from 300 °C to 100 °C via the use of HPA. The electrical characteristics of a-IGZO TFTs annealed in O2 at 2 MPa were superior to those annealed in N2 at 4 MPa, despite the lower pressure. For O2 HPA under 2 MPa at 100 °C, the field effect mobility and the threshold voltage shift under positive bias stress were improved by 9.00 to 10.58 cm(2)/V.s and 3.89 to 2.64 V, respectively. This is attributed to not only the effects of the pressurizing effect but also the metal-oxide construction effect which assists to facilitate the formation of channel layer and reduces oxygen vacancies, served as electron trap sites. PMID:26972476

  12. High-pressure Gas Activation for Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistors at 100 °C

    PubMed Central

    Kim, Won-Gi; Tak, Young Jun; Du Ahn, Byung; Jung, Tae Soo; Chung, Kwun-Bum; Kim, Hyun Jae

    2016-01-01

    We investigated the use of high-pressure gases as an activation energy source for amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs). High-pressure annealing (HPA) in nitrogen (N2) and oxygen (O2) gases was applied to activate a-IGZO TFTs at 100 °C at pressures in the range from 0.5 to 4 MPa. Activation of the a-IGZO TFTs during HPA is attributed to the effect of the high-pressure environment, so that the activation energy is supplied from the kinetic energy of the gas molecules. We reduced the activation temperature from 300 °C to 100 °C via the use of HPA. The electrical characteristics of a-IGZO TFTs annealed in O2 at 2 MPa were superior to those annealed in N2 at 4 MPa, despite the lower pressure. For O2 HPA under 2 MPa at 100 °C, the field effect mobility and the threshold voltage shift under positive bias stress were improved by 9.00 to 10.58 cm2/V.s and 3.89 to 2.64 V, respectively. This is attributed to not only the effects of the pressurizing effect but also the metal-oxide construction effect which assists to facilitate the formation of channel layer and reduces oxygen vacancies, served as electron trap sites. PMID:26972476

  13. Effects of electron trapping and interface state generation on bias stress induced in indium-gallium-zinc oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Han, Chang-Hoon; Kim, Sang-Sub; Kim, Kwang-Ryul; Baek, Do-Hyun; Kim, Sang-Soo; Choi, Byoung-Deog

    2014-08-01

    The electrical characteristics of bias temperature stress (BTS) induced in amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) were studied. We analyzed the threshold voltage (VTH) shift on the basis of the effects of positive bias temperature stress (PBTS) and negative bias temperature stress (NBTS), and applied it to the stretched-exponential model. Both stress temperature and bias are considered as important factors in the electrical instabilities of a-IGZO TFTs, and the stretched-exponential equation is well fitted to the stress condition. VTH for the drain current-gate voltage (IDS-VGS) curve and flat-band voltage (VFB) for the capacitance-voltage (C-V) curve move in the positive direction when PBTS is induced. However, in the case of NBTS, they move slightly in the negative direction. To clarify the VTH shift phenomenon by electron and hole injection, the average effective energy barrier (Eτ) is extracted, and the extracted values of Eτ under PBTS and NBTS are about 1.33 and 2.25 eV, respectively. The oxide trap charges (Not) of PBTS and NBTS calculated by C-V measurement are 4.4 × 1011 and 1.49 × 1011 cm-2, respectively. On the other hand, the border trap charges of PBTS and NBTS are 6.7 × 108 and 1.7 × 109 cm-2, respectively. This indicates that the increased interface trap charge, after PBTS is induced, captures electrons during detrap processing from the border trap to the conduction band, valence band, and interface trap.

  14. Influence of source and drain contacts on the properties of indium-gallium-zinc-oxide thin-film transistors based on amorphous carbon nanofilm as barrier layer.

    PubMed

    Luo, Dongxiang; Xu, Hua; Zhao, Mingjie; Li, Min; Xu, Miao; Zou, Jianhua; Tao, Hong; Wang, Lei; Peng, Junbiao

    2015-02-18

    Amorphous indium-gallium-zinc-oxide thin film transistors (α-IGZO TFTs) with damage-free back channel wet-etch (BCE) process were achieved by introducing a carbon nanofilm as a barrier layer. We investigate the effects of different source-and-drain (S/D) materials on TFT performance. We find the TFT with Ti/C S/D electrodes exhibits a superior performance with higher output current, lower threshold voltage, and higher effective electron mobility compared to that of Mo/C S/D electrodes. Transmittance electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are employed to analysis the interfacial interaction between S/D metal/C/α-IGZO layers. The results indicate that the better performance of TFTs with Ti/C electrodes should be attributed to the formations of Ti-C and Ti-O at the Ti/C-contact regions, which lead to a lower contact resistance, whereas Mo film is relatively stable and does not react easily with C nanofilm, resulting in a nonohmic contact behavior between Mo/C and α-IGZO layer. However, both kinds of α-IGZO TFTs show good stability under thermal bias stress, indicating that the inserted C nanofilms could avoid the impact on the α-IGZO channel regions during S/D electrodes formation. Finally, we successfully fabricated a high-definition active-matrix organic lighting emitting diode prototype driven by α-IGZO TFTs with Ti/C electrodes in a pilot line.

  15. Non-Invasive Drosophila ECG Recording by Using Eutectic Gallium-Indium Alloy Electrode: A Feasible Tool for Future Research on the Molecular Mechanisms Involved in Cardiac Arrhythmia

    PubMed Central

    Kuo, Po-Hung; Tzeng, Te-Hsuen; Huang, Yi-Chun; Chen, Yu-Hao; Chang, Yi-Chung; Ho, Yi-Lwun; Wu, June-Tai; Lee, Hsiu-Hsian; Lai, Po-Jung; Liu, Kwei-Yan; Cheng, Ya-Chen; Lu, Shey-Shi

    2014-01-01

    Background Drosophila heart tube is a feasible model for cardiac physiological research. However, obtaining Drosophila electrocardiograms (ECGs) is difficult, due to the weak signals and limited contact area to apply electrodes. This paper presents a non-invasive Gallium-Indium (GaIn) based recording system for Drosophila ECG measurement, providing the heart rate and heartbeat features to be observed. This novel, high-signal-quality system prolongs the recording time of insect ECGs, and provides a feasible platform for research on the molecular mechanisms involved in cardiovascular diseases. Methods In this study, two types of electrode, tungsten needle probes and GaIn electrodes, were used respectively to noiselessly conduct invasive and noninvasive ECG recordings of Drosophila. To further analyze electrode properties, circuit models were established and simulated. By using electromagnetic shielded heart signal acquiring system, consisted of analog amplification and digital filtering, the ECG signals of three phenotypes that have different heart functions were recorded without dissection. Results and Discussion The ECG waveforms of different phenotypes of Drosophila recorded invasively and repeatedly with n value (n>5) performed obvious difference in heart rate. In long period ECG recordings, non-invasive method implemented by GaIn electrodes acts relatively stable in both amplitude and period. To analyze GaIn electrode, the correctness of GaIn electrode model established by this paper was validated, presenting accuracy, stability, and reliability. Conclusions Noninvasive ECG recording by GaIn electrodes was presented for recording Drosophila pupae ECG signals within a limited contact area and signal strength. Thus, the observation of ECG changes in normal and SERCA-depleted Drosophila over an extended period is feasible. This method prolongs insect survival time while conserving major ECG features, and provides a platform for electrophysiological signal research

  16. Effect of direct current sputtering power on the behavior of amorphous indium-gallium-zinc-oxide thin-film transistors under negative bias illumination stress: A combination of experimental analyses and device simulation

    SciTech Connect

    Jang, Jun Tae; Kim, Dong Myong; Choi, Sung-Jin; Kim, Dae Hwan E-mail: drlife@kookmin.ac.kr; Park, Jozeph; Ahn, Byung Du; Kim, Hyun-Suk E-mail: drlife@kookmin.ac.kr

    2015-03-23

    The effect of direct current sputtering power of indium-gallium-zinc-oxide (IGZO) on the performance and stability of the corresponding thin-film transistor devices was studied. The field effect mobility increases as the IGZO sputter power increases, at the expense of device reliability under negative bias illumination stress (NBIS). Device simulation based on the extracted sub-gap density of states indicates that the field effect mobility is improved as a result of the number of acceptor-like states decreasing. The degradation by NBIS is suggested to be induced by the formation of peroxides in IGZO rather than charge trapping.

  17. The structure of the hydrated gallium(III), indium(III), and chromium(III) ions in aqueous solution. A large angle X-ray scattering and EXAFS study

    SciTech Connect

    Lindqvist-Reis, P.; Pattanaik, S.; Sandstroem, M.; Munoz-Paez, A.; Diaz-Moreno, S.; Persson, I.

    1998-12-28

    The structure of the hydrated gallium(III), indium(III), and chromium(III) ions has been determined in aqueous perchlorate and nitrate solutions by means of the large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The EXAFS studies have been performed over a wide concentration range, 0.005--1.0 mol/dm{sup 3} (2.6 mol/dm{sup 3} for chromium(III)), while the LAXS studies are restricted to concentrated solutions, ca. 1.5 mol/dm{sup 3}. All three metal ions were found to coordinate six water molecules, each of which are hydrogen bonded to two water molecules in a second hydration sphere. Analyses of the Ga, In, and Cr K-edge EXAFS data of the aqueous perchlorate and nitrate solutions showed no influence on the first shell M{single_bond}O distance by a change of concentration or anion. The minor contribution from the second sphere M{hor_ellipsis}O distance is obscured by multiple scattering within the tightly bonded first shell. EXAFS data for the alum salts CsM(SO{sub 4}){sub 2}{center_dot}12H{sub 2}O, M = Ga or In, showed the M-O bond length of the hexahydrated gallium(III) and indium(III) ions to be 1.957(2) and 2.122(2) {angstrom}, respectively.

  18. A thermalization energy analysis of the threshold voltage shift in amorphous indium gallium zinc oxide thin film transistors under simultaneous negative gate bias and illumination

    SciTech Connect

    Flewitt, A. J.; Powell, M. J.

    2014-04-07

    It has been previously observed that thin film transistors (TFTs) utilizing an amorphous indium gallium zinc oxide (a-IGZO) semiconducting channel suffer from a threshold voltage shift when subjected to a negative gate bias and light illumination simultaneously. In this work, a thermalization energy analysis has been applied to previously published data on negative bias under illumination stress (NBIS) in a-IGZO TFTs. A barrier to defect conversion of 0.65–0.75 eV is extracted, which is consistent with reported energies of oxygen vacancy migration. The attempt-to-escape frequency is extracted to be 10{sup 6}−10{sup 7} s{sup −1}, which suggests a weak localization of carriers in band tail states over a 20–40 nm distance. Models for the NBIS mechanism based on charge trapping are reviewed and a defect pool model is proposed in which two distinct distributions of defect states exist in the a-IGZO band gap: these are associated with states that are formed as neutrally charged and 2+ charged oxygen vacancies at the time of film formation. In this model, threshold voltage shift is not due to a defect creation process, but to a change in the energy distribution of states in the band gap upon defect migration as this allows a state formed as a neutrally charged vacancy to be converted into one formed as a 2+ charged vacancy and vice versa. Carrier localization close to the defect migration site is necessary for the conversion process to take place, and such defect migration sites are associated with conduction and valence band tail states. Under negative gate bias stressing, the conduction band tail is depleted of carriers, but the bias is insufficient to accumulate holes in the valence band tail states, and so no threshold voltage shift results. It is only under illumination that the quasi Fermi level for holes is sufficiently lowered to allow occupation of valence band tail states. The resulting charge localization then allows a negative threshold voltage

  19. Metal-organic chemical vapor deposition of cerium oxide, gallium-indium-oxide, and magnesium oxide thin films: Precursor design, film growth, and film characterization

    NASA Astrophysics Data System (ADS)

    Edleman, Nikki Lynn

    A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric cerium, neodymium, gadolinium, and erbium complexes are coordinatively saturated by a versatile, multidentate, ether-functionalized beta-ketoiminate ligand, and complex melting point and volatility characteristics can be tuned by altering the alkyl substituents on the ligand periphery. Direct comparison with lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD. Epitaxial CeO 2 buffer layer films have been grown on (001) YSZ substrates by MOCVD at significantly lower temperatures than previously reported using one of the newly developed cerium precursors. High-quality YBCO films grown on these CeO2 buffer layers by POMBE exhibit very good electrical transport properties. The cerium complex has therefore been explicitly demonstrated to be a stable and volatile precursor and is attractive for low-temperature growth of coated conductor multilayer structures by MOCVD. Gallium-indium-oxide thin films (GaxIn2-xO 3), x = 0.0˜1.1, have been grown by MOCVD using the volatile metal-organic precursors In(dpm)3 and Ga(dpm)3. The films have a homogeneously Ga-substituted, cubic In2O3 microstructure randomly oriented on quartz or heteroepitaxial on (100) YSZ single-crystal substrates. The highest conductivity of the as-grown films is found at x = 0.12. The optical transmission window and absolute transparency of the films rivals or exceeds that of the most transparent conductive oxides known. Reductive annealing results in improved charge transport characteristics with little loss of optical transparency. No significant difference in electrical properties is observed between randomly oriented and heteroepitaxial films, thus arguing that carrier scattering effects at high-angle grain boundaries play a minor role in the film conductivity mechanism

  20. Gallium scan

    MedlinePlus

    Liver gallium scan; Bony gallium scan ... You will get a radioactive material called gallium injected into your vein. The gallium travels through the bloodstream and collects in the bones and certain organs. Your health care provider will ...

  1. A chronic toxicity test for the tropical marine snail Nassarius dorsatus to assess the toxicity of copper, aluminium, gallium, and molybdenum.

    PubMed

    Trenfield, Melanie A; van Dam, Joost W; Harford, Andrew J; Parry, David; Streten, Claire; Gibb, Karen; van Dam, Rick A

    2016-07-01

    Chronic toxicity test methods for assessing the toxicity of contaminants to tropical marine organisms are generally lacking. A 96-h chronic growth rate toxicity test was developed for the larval stage of the tropical dogwhelk, Nassarius dorsatus. Growth rates of N. dorsatus larvae were assessed following exposures to copper (Cu), aluminium (Al), gallium (Ga), and molybdenum (Mo). Exposure to Cu at 28 °C validated the sensitivity of the test method, with 10% (EC10) and 50% (EC50) effect concentrations of 4.2 μg/L and 7.3 μg/L Cu, respectively. The EC10 and EC50 values for Al (<0.45-μm filtered fraction) at 28 °C were 115 μg/L and 185 μg/L, respectively. The toxicity of Cu and Al was also assessed at 24 °C and 31 °C, representing average year-round water temperatures for subtropical and tropical Australian coastal environments. At 24 °C, the growth rate of control larvae was reduced by 52% compared with the growth rate at 28 °C and there was an increase in sensitivity to Cu (EC50 = 4.7 μg/L) but a similar sensitivity to Al (EC50 = 180 μg/L). At 31 °C the control growth rate increased by 35% from that measured at 28 °C and there was reduced sensitivity to both Cu and Al (EC50s = 8.5 μg/L and 642 μg/L, respectively). There was minimal toxicity resulting from Ga (EC50 = 4560 μg/L) and Mo (no effect at ≤7000 μg/L Mo). Environ Toxicol Chem 2016;35:1788-1795. © 2015 SETAC. PMID:26643415

  2. A chronic toxicity test for the tropical marine snail Nassarius dorsatus to assess the toxicity of copper, aluminium, gallium, and molybdenum.

    PubMed

    Trenfield, Melanie A; van Dam, Joost W; Harford, Andrew J; Parry, David; Streten, Claire; Gibb, Karen; van Dam, Rick A

    2016-07-01

    Chronic toxicity test methods for assessing the toxicity of contaminants to tropical marine organisms are generally lacking. A 96-h chronic growth rate toxicity test was developed for the larval stage of the tropical dogwhelk, Nassarius dorsatus. Growth rates of N. dorsatus larvae were assessed following exposures to copper (Cu), aluminium (Al), gallium (Ga), and molybdenum (Mo). Exposure to Cu at 28 °C validated the sensitivity of the test method, with 10% (EC10) and 50% (EC50) effect concentrations of 4.2 μg/L and 7.3 μg/L Cu, respectively. The EC10 and EC50 values for Al (<0.45-μm filtered fraction) at 28 °C were 115 μg/L and 185 μg/L, respectively. The toxicity of Cu and Al was also assessed at 24 °C and 31 °C, representing average year-round water temperatures for subtropical and tropical Australian coastal environments. At 24 °C, the growth rate of control larvae was reduced by 52% compared with the growth rate at 28 °C and there was an increase in sensitivity to Cu (EC50 = 4.7 μg/L) but a similar sensitivity to Al (EC50 = 180 μg/L). At 31 °C the control growth rate increased by 35% from that measured at 28 °C and there was reduced sensitivity to both Cu and Al (EC50s = 8.5 μg/L and 642 μg/L, respectively). There was minimal toxicity resulting from Ga (EC50 = 4560 μg/L) and Mo (no effect at ≤7000 μg/L Mo). Environ Toxicol Chem 2016;35:1788-1795. © 2015 SETAC.

  3. Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control.

    PubMed

    Sarkar, Sujoy; Sampath, S

    2016-05-11

    A ternary, ionically conducting, deep eutectic solvent based on acetamide, urea and gallium nitrate is reported for the electrodeposition of gallium nitride/gallium indium nitride under ambient conditions; blue and white light emitting photoluminescent deposits are obtained under potential control. PMID:27074315

  4. High-performance low-cost back-channel-etch amorphous gallium-indium-zinc oxide thin-film transistors by curing and passivation of the damaged back channel.

    PubMed

    Park, Jae Chul; Ahn, Seung-Eon; Lee, Ho-Nyeon

    2013-12-11

    High-performance, low-cost amorphous gallium-indium-zinc oxide (a-GIZO) thin-film-transistor (TFT) technology is required for the next generation of active-matrix organic light-emitting diodes. A back-channel-etch structure is the most appropriate device structure for high-performance, low-cost a-GIZO TFT technology. However, channel damage due to source/drain etching and passivation-layer deposition has been a critical issue. To solve this problem, the present work focuses on overall back-channel processes, such as back-channel N2O plasma treatment, SiOx passivation deposition, and final thermal annealing. This work has revealed the dependence of a-GIZO TFT characteristics on the N2O plasma radio-frequency (RF) power and frequency, the SiH4 flow rate in the SiOx deposition process, and the final annealing temperature. On the basis of these results, a high-performance a-GIZO TFT with a field-effect mobility of 35.7 cm(2) V(-1) s(-1), a subthreshold swing of 185 mV dec(-1), a switching ratio exceeding 10(7), and a satisfactory reliability was successfully fabricated. The technology developed in this work can be realized using the existing facilities of active-matrix liquid-crystal display industries. PMID:24221957

  5. Improvement of bias-stability in amorphous-indium-gallium-zinc-oxide thin-film transistors by using solution-processed Y{sub 2}O{sub 3} passivation

    SciTech Connect

    An, Sungjin; Mativenga, Mallory; Kim, Youngoo; Jang, Jin

    2014-08-04

    We demonstrate back channel improvement of back-channel-etch amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors by using solution-processed yttrium oxide (Y{sub 2}O{sub 3}) passivation. Two different solvents, which are acetonitrile (35%) + ethylene glycol (65%), solvent A and deionized water, solvent B are investigated for the spin-on process of the Y{sub 2}O{sub 3} passivation—performed after patterning source/drain (S/D) Mo electrodes by a conventional HNO{sub 3}-based wet-etch process. Both solvents yield devices with good performance but those passivated by using solvent B exhibit better light and bias stability. Presence of yttrium at the a-IGZO back interface, where it occupies metal vacancy sites, is confirmed by X-ray photoelectron spectroscopy. The passivation effect of yttrium is more significant when solvent A is used because of the existence of more metal vacancies, given that the alcohol (65% ethylene glycol) in solvent A may dissolve the metal oxide (a-IGZO) through the formation of alkoxides and water.

  6. Low-power scan driver embedded with level shifter using depletion-mode amorphous indium-gallium-zinc-oxide thin-film transistors for high-resolution flat-panel displays

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Hee; Kwon, Oh-Kyong

    2014-01-01

    A low-power scan driver embedded with a level shifter using depletion-mode amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) is proposed for high-resolution flat-panel displays (FPDs). In order to achieve low power consumption, the scan driver uses clock signals with a reduced voltage swing. Furthermore, the level shifter is implemented without using a diode-connected TFT. This scan driver is simulated at an output voltage swing of 30 V and an operating frequency (fop) of 153.6 kHz, which satisfy the driving conditions for 10-in. wide quadruple extended graphics array (WQXGA, 1600 × 2560) FPDs with a frame frequency of 60 Hz. The simulation results of the proposed scan driver demonstrate the successful operation even at a threshold voltage shift (ΔVth) of -2.0 V. The power consumption of the proposed scan driver per ten stages is 0.41 mW, which is 80.75% less than that reported in a previous work.

  7. Remarkable changes in interface O vacancy and metal-oxide bonds in amorphous indium-gallium-zinc-oxide thin-film transistors by long time annealing at 250 °C

    SciTech Connect

    Chowdhury, Md Delwar Hossain; Um, Jae Gwang; Jang, Jin

    2014-12-08

    We have studied the effect of long time post-fabrication annealing on negative bias illumination stress (NBIS) of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film-transistors. Annealing for 100 h at 250 °C increased the field effect mobility from 14.7 cm{sup 2}/V s to 17.9 cm{sup 2}/V s and reduced the NBIS instability remarkably. Using X-ray photoelectron spectroscopy, the oxygen vacancy and OH were found to exist at the interfaces of a-IGZO with top and bottom SiO{sub 2}. Long time annealing helps to decrease the vacancy concentration and increase the metal-oxygen bonds at the interfaces; this leads to increase in the free carrier concentrations in a-IGZO and field-effect mobility. X-ray reflectivity measurement indicated the increment of a-IGZO film density of 5.63 g cm{sup −3} to 5.83 g cm{sup −3} (3.4% increase) by 100 h annealing at 250 °C. The increase in film density reveals the decrease of O vacancy concentration and reduction of weak metal-oxygen bonds in a-IGZO, which substantially helps to improve the NBIS stability.

  8. Influence of the charge trap density distribution in a gate insulator on the positive-bias stress instability of amorphous indium-gallium-zinc oxide thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Eungtaek; Kim, Choong-Ki; Lee, Myung Keun; Bang, Tewook; Choi, Yang-Kyu; Park, Sang-Hee Ko; Choi, Kyung Cheol

    2016-05-01

    We investigated the positive-bias stress (PBS) instability of thin film transistors (TFTs) composed of different types of first-gate insulators, which serve as a protection layer of the active surface. Two different deposition methods, i.e., the thermal atomic layer deposition (THALD) and plasma-enhanced ALD (PEALD) of Al2O3, were applied for the deposition of the first GI. When THALD was used to deposit the GI, amorphous indium-gallium-zinc oxide (a-IGZO) TFTs showed superior stability characteristics under PBS. For example, the threshold voltage shift (ΔVth) was 0 V even after a PBS time (tstress) of 3000 s under a gate voltage (VG) condition of 5 V (with an electrical field of 1.25 MV/cm). On the other hand, when the first GI was deposited by PEALD, the ΔVth value of a-IGZO TFTs was 0.82 V after undergoing an identical amount of PBS. In order to interpret the disparate ΔVth values resulting from PBS quantitatively, the average oxide charge trap density (NT) in the GI and its spatial distribution were investigated through low-frequency noise characterizations. A higher NT resulted during in the PEALD type GI than in the THALD case. Specifically, the PEALD process on a-IGZO layer surface led to an increasing trend of NT near the GI/a-IGZO interface compared to bulk GI owing to oxygen plasma damage on the a-IGZO surface.

  9. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    NASA Astrophysics Data System (ADS)

    Burghoorn, M.; Kniknie, B.; van Deelen, J.; Xu, M.; Vroon, Z.; van Ee, R.; van de Belt, R.; Buskens, P.

    2014-12-01

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (Jsc) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the Jsc and efficiency of CIGS solar cells with an absorber layer thickness (dCIGS) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (nresist = 1.792 vs. nAZO = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, Jsc increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in Jsc with decreasing dCIGS was observed. Ergo, the increase in Jsc can be fully explained by the reduction in reflection, and we did not observe any increase in Jsc based on an increased photon path length.

  10. Improving the efficiency of copper indium gallium (Di-)selenide (CIGS) solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    SciTech Connect

    Burghoorn, M.; Kniknie, B.; Deelen, J. van; Ee, R. van; Xu, M.; Vroon, Z.; Belt, R. van de; Buskens, P. E-mail: buskens@dwi.rwth-aachen.de

    2014-12-15

    Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (J{sub sc}) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the J{sub sc} and efficiency of CIGS solar cells with an absorber layer thickness (d{sub CIGS}) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (n{sub resist} = 1.792 vs. n{sub AZO} = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, J{sub sc} increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in J{sub sc} with decreasing d{sub CIGS} was observed. Ergo, the increase in J{sub sc} can be fully explained by the reduction in reflection, and we did not observe any increase in J{sub sc} based on an increased photon path length.

  11. The Availability of Indium: The Present, Medium Term, and Long Term

    SciTech Connect

    Lokanc, Martin; Eggert, Roderick; Redlinger, Michael

    2015-10-01

    Demand for indium is likely to increase if the growth in deployment of the copper-indium-gallium-selenide (CIGS) and III-V thin-film photovoltaic technologies accelerates. There are concerns about indium supply constraints since it is relatively rare element in the earth's crust and because it is produced exclusively as a byproduct.

  12. Aluminium plasmonics

    SciTech Connect

    Gerard, Davy; Gray, Stephen K.

    2014-12-15

    In this study, we present an overview of 'aluminium plasmonics', i.e. the study of both fundamental and practical aspects of surface plasmon excitations in aluminium structures, in particular thin films and metal nanoparticles. After a brief introduction noting both some recent and historical contributions to aluminium plasmonics, we discuss the optical properties of aluminium and aluminium nanostructures and highlight a few selected studies in a host of areas ranging from fluorescence to data storage.

  13. The Kagomé topology of the gallium and indium metal-organic framework types with a MIL-68 structure: synthesis, XRD, solid-state NMR characterizations, and hydrogen adsorption.

    PubMed

    Volkringer, Christophe; Meddouri, Mohamed; Loiseau, Thierry; Guillou, Nathalie; Marrot, Jérôme; Férey, Gérard; Haouas, Mohamed; Taulelle, Francis; Audebrand, Nathalie; Latroche, Michel

    2008-12-15

    The vanadium-based terephthalate analogs of MIL-68 have been obtained with gallium and indium (network composition: M(OH)(O(2)C-C(6)H(4)-CO(2)), M = Ga or In) by using a solvothermal synthesis technique using N,N-dimethylformamide as a solvent (10 and 48 h, for Ga and In, respectively, at 100 degrees C). They have been characterized by X-ray diffraction analysis; vibrational spectroscopy; and solid-state (1)H and (1)H-(1)H radio-frequency-driven dipolar recoupling (RFDR), (1)H-(1)H double quantum correlation (DQ), and (13)C{(1)H} cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The three-dimensional network with a Kagomé-like lattice is built up from the connection of infinite trans-connected chains of octahedral units MO(4)(OH)(2) (M = Ga or In), linked to each other through the terephthalate ligands in order to generate triangular and hexagonal one-dimensional channels. The presence of DMF molecules with strong interactions within the channels as well as their departure upon calcination (150 degrees C under a primary vacuum) of the materials has been confirmed by subjecting MIL-68 (Ga) to solid-state (1)H MAS NMR. The (1)H-(1)H RFDR and (1)H-(1)H DQ spectra revealed important information on the spatial arrangement of the guest species with respect to the hybrid organic-inorganic network. (13)C{(1)H} CPMAS NMR of activated samples provided crystallographically independent sites in agreement with X-ray diffraction structure determination. Brunauer-Emmett-Teller surface areas are 1117(24) and 746(31) m(2) g(-1) for MIL-98 (Ga) and MIL-68 (In), respectively. Hydrogen adsorption isotherms have been measured at 77 K, and the storage capacities are found to be 2.46 and 1.98 wt % under a saturated pressure of 4 MPa for MIL-68 (Ga) and MIL-68 (In), respectively. For comparison, the hydrogen uptake for the aluminum trimesate MIL-110, which has an open framework with 16 A channels, is 3 wt % under 4 MPa.

  14. Indium gallium arsenide microwave power transistors

    NASA Technical Reports Server (NTRS)

    Johnson, Gregory A.; Kapoor, Vik J.; Shokrani, Mohsen; Messick, Louis J.; Nguyen, Richard

    1991-01-01

    Depletion-mode InGaAs microwave power MISFETs with 1-micron gate lengths and up to 1-mm gate widths have been fabricated using an ion-implantation process. The devices employed a plasma-deposited silicon/silicon dioxide gate insulator. The dc I-V characteristics and RF power performance at 9.7 GHz are presented. The output power, power-added efficiency, and power gain as a function of input power are reported. An output power of 1.07 W with a corresponding power gain and power-added efficiency of 4.3 dB and 38 percent, respectively, was obtained. The large-gate-width devices provided over twice the previously reported output power for InGaAs MISFETs at X-band. In addition, output power stability within 1.2 percent over 24 h of continuous operation was achieved. In addition, a drain current drift of 4 percent over 10,000 sec was obtained.

  15. Running droplets of gallium from evaporation of gallium arsenide.

    PubMed

    Tersoff, J; Jesson, D E; Tang, W X

    2009-04-10

    High-temperature annealing of gallium arsenide in vacuum causes excess evaporation of arsenic, with accumulation of gallium as liquid droplets on the surface. Using real-time in situ surface electron microscopy, we found that these droplets spontaneously run across the crystal surface. Running droplets have been seen in many systems, but they typically require special surface preparation or gradient forces. In contrast, we show that noncongruent evaporation automatically provides a driving force for running droplets. The motion is predicted and observed to slow and stop near a characteristic temperature, with the speed increasing both below and above this temperature. The same behavior is expected to occur during the evaporation of similar III-V semiconductors such as indium arsenide.

  16. Gallium complexes and solvent extraction of gallium

    SciTech Connect

    Coleman, J.P.; Graham, C.R.; Monzyk, B.F.

    1988-05-03

    This patent describes a process for recovering gallium from aqueous solutions containing gallium which comprises contacting such a solution with an organic solvent containing at least 2% by weight of a water-insoluble N-organo hydroxamic acid having at least about 8 carbon atoms to extract gallium, and separating the gallium loaded organic solvent phase from the aqueous phase.

  17. Highly efficient blue organic light emitting device using indium-free transparent anode Ga:ZnO with scalability for large area coating

    SciTech Connect

    Wang, Liang; Matson, Dean W.; Polikarpov, Evgueni; Swensen, James S.; Bonham, Charles C.; Cosimbescu, Lelia; Berry, J. J.; Ginley, D. S.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

    2010-02-15

    The availability of economically-produced and environmentally-stable transparent conductive oxide (TCO) coatings is critical for the development of a variety of electronic devices requiring transparent electrodes. Such devices include liquid crystal display pixels and organic light emitting diodes (OLEDs),[1, 2] solar cell applications,[3, 4] and electrically heated windows.[5, 6] The materials fulfilling these requirements are usually wide band gap inorganic transparent conductive oxides (TCOs). Tin-doped indium oxide, or ITO, has traditionally been used for electronic TCO applications because of its low resistivity, high work function and transparency. Due to the increasing cost and limited supply of indium and its tendency to migrate in to the device, there has been increasing research interest to substitute ITO with an indium-free material. A number of alternative metal oxides and doped oxides have been evaluated as TCO materials with varying degrees of success.[7, 8] Among these alternatives to ITO, gallium-doped zinc oxide (GZO) [2, 9] and aluminium-doped zinc oxide (AZO) [10, 11] have drawn particular attention. These materials have been demonstrated to have resistivities and transparencies approaching those of the best ITO, low toxicity, and much lower materials cost. Although AZO is attractive as a TCO electrode material, GZO features a greater resistance to oxidation as a result of gallium’s greater electronegativity compared to Submitted to 2 aluminum.[12, 13

  18. [Mechanism of renal elimination of 2 elements of group IIIA of the periodic table : aluminum and indium].

    PubMed

    Galle, P

    1981-01-01

    Aluminium and indium, two elements of group IIIA of the periodic table, are concentrated by the kidney inside lysosomes of proximal tubule cell. In these lysosomes, aluminium and indium are precipitated as non-soluble phosphate salts and these precipitates are then expelled in the tubular lumen and eliminated with the urinary flow. These data have been visualized by analytical microscopy (ion microscopy and X ray microanalysis). Local acid phosphatases are assumed to permit the concentration of aluminium and indium salts inside the lysosomes.

  19. Determination of submicrogram amounts of gallium by ion-exchanger fluorimetry Determination of gallium in natural waters.

    PubMed

    Capitan, F; Navalon, A; Vilchez, J L; Capitan-Vallvey, L F

    1990-02-01

    A method for microdetermination of gallium at ng/ml level has been developed, based on ion-exchanger fluorimetry. The gallium reacts with salicylidene-o-aminophenol to give a highly fluorescent complex, which is fixed on a dextran-type cationic resin. The fluorescence of the resin, packed in a 1-mm silica cell, is measured directly with a solid-surface attachment. The range of concentration of the method is 2.0-10.0 ng/ml, the RSD 1.3% and the detection limit 0.3 ng/ml. The method has been applied to the determination of gallium in natural waters. The gallium content found in tap water was higher than that in raw water. This is related to the use of commercial aluminium salts in the water-treatment plant. PMID:18964929

  20. The role of hydrous ferric oxide precipitation in the fractionation of arsenic, gallium, and indium during the neutralization of acidic hot spring water by river water in the Tama River watershed, Japan

    NASA Astrophysics Data System (ADS)

    Ogawa, Yasumasa; Ishiyama, Daizo; Shikazono, Naotatsu; Iwane, Kenta; Kajiwara, Masahiro; Tsuchiya, Noriyoshi

    2012-06-01

    The Obuki spring is the largest and most acidic of the Tamagawa hot springs (Akita Prefecture, northern Japan), and it discharges ca. 9000 L/min of chloride-rich acidic water (pH 1.2) that contains high concentrations of both As and rare metals such as Ga and In. This paper aims to quantify seasonal variations in the mobility of these elements in the Shibukuro and Tama rivers, which are fed by the thermal waters of the Obuki spring, caused by sorption onto hydrous ferric oxide (HFO). Seasonal observations revealed the following relationships with respect to As removal by HFO: (a) the oxidation of Fe2+ is predominantly controlled by both pH and water temperature, and progresses more quickly in less acidic and warmer conditions; (b) HFO formation was predominantly controlled by pH; and (c) the removal of dissolved arsenate is directly related to the amount of HFO present. Consequently, the oxidation to Fe3+ was slower during periods of cold and lower pH, and the amount of HFO was too small to remove the dissolved arsenate effectively. Consequently, considerable amounts of dissolved arsenate and Fe2+ remained in river water. In contrast, when HFO production from Fe3+ increased, and dissolved arsenate was removed during warmer and less acidic periods, only small amounts of dissolved arsenite and Fe2+ remained in the river water. The geochemical behavior of Ga and In was essentially controlled by pH; however, when HFO production was limited by a pH of less than 3.5, Ga behavior was controlled mainly by the amount of HFO. Gallium tended to be sorbed under more acidic conditions than was In. Due to differences in sorption behavior, Ga, As, and In were fractionated during sedimentation. In the upstream reaches, arsenate and dissolved Ga sorbed onto HFO, and were widely distributed across the watershed. Conversely, dissolved In was removed by HFO downstream. As a result, In is relatively concentrated on the downstream lakebed, unlike As and Ga, and In-rich mineral deposits

  1. Gallium nitride optoelectronic devices

    NASA Technical Reports Server (NTRS)

    Chu, T. L.; Chu, S. S.

    1972-01-01

    The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.

  2. Investigations in gallium removal

    SciTech Connect

    Philip, C.V.; Pitt, W.W.; Beard, C.A.

    1997-11-01

    Gallium present in weapons plutonium must be removed before it can be used for the production of mixed-oxide (MOX) nuclear reactor fuel. The main goal of the preliminary studies conducted at Texas A and M University was to assist in the development of a thermal process to remove gallium from a gallium oxide/plutonium oxide matrix. This effort is being conducted in close consultation with the Los Alamos National Laboratory (LANL) personnel involved in the development of this process for the US Department of Energy (DOE). Simple experiments were performed on gallium oxide, and cerium-oxide/gallium-oxide mixtures, heated to temperatures ranging from 700--900 C in a reducing environment, and a method for collecting the gallium vapors under these conditions was demonstrated.

  3. Aluminium in human sweat.

    PubMed

    Minshall, Clare; Nadal, Jodie; Exley, Christopher

    2014-01-01

    It is of burgeoning importance that the human body burden of aluminium is understood and is measured. There are surprisingly few data to describe human excretion of systemic aluminium and almost no reliable data which relate to aluminium in sweat. We have measured the aluminium content of sweat in 20 healthy volunteers following mild exercise. The concentration of aluminium ranged from 329 to 5329μg/L. These data equate to a daily excretion of between 234 and 7192μg aluminium and they strongly suggest that perspiration is the major route of excretion of systemic aluminium in humans.

  4. Evidence of aluminium accumulation in aluminium welders.

    PubMed Central

    Elinder, C G; Ahrengart, L; Lidums, V; Pettersson, E; Sjögren, B

    1991-01-01

    Using atomic absorption spectrometry the aluminium concentrations in blood and urine and in two iliac bone biopsies obtained from welders with long term exposure to fumes containing aluminium were measured. The urinary excretion of two workers who had welded for 20 and 21 years varied between 107 and 351 micrograms Al/l, more than 10 times the concentration found in persons without occupational exposure. Urinary aluminium excretion remained high many years after stopping exposure. Blood and bone aluminium concentrations (4-53 micrograms Al/l and 18-29 micrograms Al/g respectively) were also raised but not to the same extent as urine excretion. It is concluded that long term exposure to aluminium by inhalation gives rise to accumulation of aluminium in the body and skeleton of health persons, and that the elimination of retained aluminium is very slow, in the order of several years. PMID:1954151

  5. Gallium nitrate revisited.

    PubMed

    Chitambar, Christopher R

    2003-04-01

    Gallium nitrate, the nitrate salt of the "near-metal" element gallium, is highly effective in the treatment of cancer-related hypercalcemia. Unlike bisphosphonates, gallium nitrate is effective in both parathyroid hormone-related protein-mediated and non-parathyroid hormone-related protein-mediated hypercalcemia. Gallium nitrate's effects on bone are clearly different from those of bisphosphonates. Gallium nitrate enhances calcium and phosphate content of bone and has direct, noncytotoxic effects on osteoclasts at markedly lower doses than those used for the treatment of cancer-related hypercalcemia. The drug may have clinical application in a variety of disorders associated with accelerated bone loss, including multiple myeloma. Gallium nitrate was originally evaluated as an antitumor agent. Its antitumor activity occurs at somewhat higher doses than those used in the treatment of cancer-related hypercalcemia. Gallium nitrate has substantial single-agent activity in the treatment of advanced lymphoma, particularly diffuse large cell lymphoma, small lymphocytic lymphoma, and follicular lymphoma. Because of its profile, including a different mechanism of action and minimal myelosuppression, the drug merits further evaluation in the treatment of advanced lymphoma. Gallium nitrate also has activity in advanced bladder cancer and may be useful in patients with metastatic or unresectable disease failing first-line chemotherapy regimens. Gallium nitrate exhibits a range of dose-dependent pharmacologic actions that provide a basis for its therapeutic potential in a variety of diseases and warrants further investigational evaluation as an antiresorptive and antitumor agent. PMID:12776253

  6. Regularly arranged indium islands on glass/molybdenum substrates upon femtosecond laser and physical vapor deposition processing

    NASA Astrophysics Data System (ADS)

    Ringleb, F.; Eylers, K.; Teubner, Th.; Boeck, T.; Symietz, C.; Bonse, J.; Andree, S.; Krüger, J.; Heidmann, B.; Schmid, M.; Lux-Steiner, M.

    2016-03-01

    A bottom-up approach is presented for the production of arrays of indium islands on a molybdenum layer on glass, which can serve as micro-sized precursors for indium compounds such as copper-indium-gallium-diselenide used in photovoltaics. Femtosecond laser ablation of glass and a subsequent deposition of a molybdenum film or direct laser processing of the molybdenum film both allow the preferential nucleation and growth of indium islands at the predefined locations in a following indium-based physical vapor deposition (PVD) process. A proper choice of laser and deposition parameters ensures the controlled growth of indium islands exclusively at the laser ablated spots. Based on a statistical analysis, these results are compared to the non-structured molybdenum surface, leading to randomly grown indium islands after PVD.

  7. Human exposure to aluminium.

    PubMed

    Exley, Christopher

    2013-10-01

    Human activities have circumvented the efficient geochemical cycling of aluminium within the lithosphere and therewith opened a door, which was previously only ajar, onto the biotic cycle to instigate and promote the accumulation of aluminium in biota and especially humans. Neither these relatively recent activities nor the entry of aluminium into the living cycle are showing any signs of abating and it is thus now imperative that we understand as fully as possible how humans are exposed to aluminium and the future consequences of a burgeoning exposure and body burden. The aluminium age is upon us and there is now an urgent need to understand how to live safely and effectively with aluminium.

  8. Microbial interactions with aluminium.

    PubMed

    Piña, R G; Cervantes, C

    1996-07-01

    Although aluminium is the most abundant metal in the Earth's crust, it lacks biological functions and shows a low bioavailability. Acid rain, however, solubilizes aluminium to toxic levels. Most research on the biological effects of aluminium has been centred on the analysis of aluminium-tolerant plants as well as its possible relationship with neurological disorders in humans. Also, several studies have been reported concerning aluminium effects on microorganisms, with more interest directed to cyanobacteria, soil bacteria and mycorrhizal fungi. Competition with iron and magnesium, and binding to DNA, membranes or cell walls are considered the main toxic effects of aluminium in microbes.

  9. Indium-111-labeled leukocyte localization in hematomas: a pitfall in abscess detection

    SciTech Connect

    Wing, V.W.; vanSonnenberg, E.; Kipper, S.; Bieberstein, M.P.

    1984-07-01

    Indium-111-labeled white-blood-cell scanning is a useful modality in abscess detection and has replaced gallium scanning in many institutions. Sensitivities of 72% to 90% and specificities of 90% to 100% have been reported. In searching for abscesses seven cases of indium-111-labeled leukocyte uptake were encountered in collections subsequently proved to be noninfected hematomas. Abundant red blood cells with few or no white blood cells, no bacteria, and a benign clinical course identified these noninfected hematomas. Five of the patients were being treated with hemodialysis and three were recent allograft recipients. The results indicate some limitation and nonspecificity in indium-111 scanning, despite its many benefits.

  10. Metals fact sheet - indium

    SciTech Connect

    1994-01-01

    Indium is generally found in concentrations averaging 10 to 20 ppm in sphalerite and chalcopyrite ores associated with zinc, copper, lead and tin deposits. Indium is recovered as a by-product of base metal mining by open pit, underground and other methods. After the recovery of zinc by the electrolytic process (copper concentrate by flotation, and lead and tin by electrolysis), indium antimonide slimes left on the anode and the indium-containing spent electrolyte become the input material for the processing of indium. Sulfuric acid is combined with the residues and heated to form sulfates which are then leached with water to filter off the remaining tin, lead and antimony. The indium in solution is recovered by cementation on aluminum, washed, melted, and refined into a metal.

  11. Indium-111 leukocyte scintigraphic detection of subclinical osteomyelitis complicating delayed and nonunion long bone fractures: a prospective study

    SciTech Connect

    Esterhai, J.L. Jr.; Goll, S.R.; McCarthy, K.E.; Velchik, M.; Alavi, A.; Brighton, C.T.; Heppenstall, R.B.

    1987-01-01

    Twenty patients were studied prospectively with indium-labeled leukocyte imaging to evaluate its effectiveness in differentiating noninfected delayed or nonunion from osteomyelitis complicating these entities. All patients underwent an open surgical procedure within 24 h of the scan. Bone specimens from the nonunion site were obtained for microbiological and histological analysis to confirm the presence or absence of osteomyelitis. In these twenty patients, the sensitivity of the indium scintigraphy was 100%, the specificity 100%, and the overall accuracy 100%. Indium-labeled leukocyte scintigraphy is significantly more accurate than /sup 99m/technetium and /sup 67/gallium imaging had been, when studied earlier, in detecting subclinical osteomyelitis complicating nonunion. Indium-labeled leukocyte scintigraphy should supplant sequential technetium and gallium studies in this patient population when the surgeon must determine whether subclinical osteomyelitis is complicating fracture management of delayed and nonunions.

  12. (Gallium arsenide solar cells)

    SciTech Connect

    Not Available

    1985-01-01

    A transient liquid phase epitaxial growth system is described, including the growth procedure. Also discussed are the antireflection coating of a gallium arsenide solar cell, the metal contact pattern, and current-voltage characteristics. (LEW)

  13. Lung gallium scan

    MedlinePlus

    ... inflammation in the lungs, most often due to sarcoidosis or a certain type of pneumonia. Normal Results ... up very little gallium. What Abnormal Results Mean Sarcoidosis Other respiratory infections, most often pneumocystis jirovecii pneumonia ...

  14. Properties of gallium arsenide

    SciTech Connect

    Not Available

    1985-01-01

    Properties of Gallium Arsenide' is a handbook of evaluated numeric data and reviewed knowledge distilled by those working at the frontiers of gallium arsenide research. In addition to providing numeric data on basic physical, electronic and optical properties, the book covers many device-related aspects of gallium arsenide. Carrier attributes (ionisation coefficients, concentration, mobility, diffusion etc), deep levels and defects are surveyed and related to the various growth techniques such as MBE, VPE, and MOCVD. Sections on surface structure, oxidation, interfaces and etching are of particular relevance to integrated circuit research. Especially important in the race to achieve commercially usable samples is a state-of-the-art survey on the infra-red imaging of defects in semi-insulating gallium arsenide produced by the liquid-encapsulated Czochralski process.

  15. Determination of indium and tin by activation analysis using replacement substoichiometry.

    PubMed

    Obrusník, I

    1969-05-01

    A new method for the determination of indium by activation analysis has been developed. It is based on the replacement of indium from indium dithizonate (in carbon tetrachloride) by a substoichiometric amount of aqueous mercury(II) solution. Preliminary steps are the extraction of indium from alkaline cyanide solution with an excess of dithizone solution and washing the extract with buffer solution. The time necessary for the separation is 10-20 min. With this method indium can be determined by using either short ((116m)In, t(1 2 ) = 54 min) or long-lived radioisotopes ((114m)In, t(1 2 = 50 d). As by the reaction (112)Sn (n, gamma)) (113)Sn (119d) --> (113)In (104 min), indium-113m is formed, which has a different gamma-spectrum from that of indium-114m, the determination of both indium and tin is possible. The proposed method has been applied to the determination of indium and tin in granite and gallium.

  16. Preventing Supercooling Of Gallium

    NASA Technical Reports Server (NTRS)

    Massucco, Arthur A.; Wenghoefer, Hans M.; Wilkins, Ronnie

    1994-01-01

    Principle of heterogeneous nucleation exploited to prevent gallium from supercooling, enabling its use as heat-storage material that crystallizes reproducibly at its freezing or melting temperature of 29 to 30 degrees C. In original intended application, gallium used as heat-storage material in gloves of space suits. Terrestrial application lies in preparation of freezing-temperature reference samples for laboratories. Principle of heterogeneous nucleation also exploited similarly in heat pipes filled with sodium.

  17. Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes.

    PubMed

    Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

    2015-01-01

    Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100-270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies.

  18. Optical characterization of copper indium gallium diselenide thin films

    NASA Astrophysics Data System (ADS)

    Hebert, Damon

    Cu(In,Ga)Se2 (CIGS) and its alloys are the leading choice for thin film photovoltaic absorber layers due to their high performance in devices, low degradation, high optical absorption coefficient and high tolerance to off-stoichiometry and intrinsic defects. Film conductivity and recombination losses are controlled by intrinsic point defect concentrations, especially in the near-surface space-charge region of the heterojunction. Despite the amount of research already performed on CIGS alloys, their optoelectronic properties, defect chemistry and recombination mechanisms are still poorly understood. The focus of this dissertation is to optically characterize a selection of CIGS absorber layers fabricated by various techniques in order to better understand the radiative emission and defect physics. This work aims to identify the defects responsible for recombination and their relation to grain boundaries and band edge fluctuations, which limit device performance. This study used photoluminescence (PL) spectroscopy, photoluminescence excitation (PLE) spectroscopy, and cathodoluminescence (CL) to study radiative emissions from a variety of Cu-poor CIGS thin films. Three general types of CIGS films were analyzed. Polycrystalline layers deposited on Mo-coated soda lime glass, polycrystalline layers deposited on metal foil, and epitaxial films grown on (100) and (111) GaAs were analyzed in this work. This work concludes that the donor-acceptor pair recombination model used in most interpretations of CIGS emission should be replaced with a model that accounts for high compensation and band edge fluctuations, which is shown to be undoubtedly the case in Cu-poor CIGS. Within this model, the most commonly observed emissions were explained as free-to-bound types, specifically iii band-to-impurity (BI) and tail-to-impurity (TI) types. Band tail width was measured by PLE. A correlation was established between band tail width and device efficiency. CIGS absorber layers that produced devices of higher performance showed narrower band tails. CL and PL showed an additional deep emission in Na-free films, not present in Na-containing films grown in parallel. It is concluded that most grain boundaries in CIGS act as collection areas for point defects and point defect clusters but also are more or less inactive with respect to recombination due to their built-in electrostatic hole barrier. Spectral and spatial emission characteristics were studied on plan-view CIGS surfaces that were covered with a ˜50 nm thick CdS film by chemical bath deposition (CBD). It is concluded that spectral changes that others have observed in the emission of CdS-treated films is a result of the CBD process itself and not the resulting film or the formation of the heterojunction. The effect of low temperature (˜180°C) air annealing on the emission characteristics of CdS/CIGS thin films was studied by cryogenic infrared and visible PL. Spectral shape was not significantly affected by annealing for either film, but PL intensity did show some dependence on anneal time for both films, which led to an estimate of an optimal time window of 3-10 hours for low temperature annealing.

  19. Auger Recombination in Indium Gallium Nitride: Experimental Evidence

    NASA Astrophysics Data System (ADS)

    Krames, Michael

    2010-03-01

    Progress in InGaN-based light-emitting diode (LED) technology has resulted in white-light emitters with efficiencies far exceeding those of conventional light sources such as tungsten-filament-based incandescence and mercury-vapor based fluorescence. Indeed, by now efficacies exceeding 150 lumens per Watt for InGaN-based phosphor-converted white LEDs are claimed, which represent a 90% energy savings compared to the conventional incandescent (i.e., ``light bulb'') solution. However, these high performance levels are obtained under conditions of very low forward current-density for the InGaN LED and do not represent true operating conditions (nor cost-effective utilization) for the device. In order to reduce the cost (and thus increase market penetration of) solid-state lighting, more lumens per unit of semiconductor area are required which in practice necessitates higher drive current densities. Unfortunately, at these higher driver current densities, the internal quantum efficiency of InGaN-based LEDs is observed to decrease significantly. In the fall of 2007, researchers at the Advanced Laboratories of Philips Lumileds were the first to propose Auger recombination as the root-cause mechanism in InGaN which was behind this ``efficiency droop'' [1]. They further proposed to circumvent the problem by employing InGaN-based active region designs that maintain low carrier density, and demonstrated an LED device design that reaches a maximum quantum efficiency above 200 A/cm2, compared to ˜1-10 A/cm^2 for typical multiple-quantum-well heterostructures [2]. In this talk we will review the experimental evidence for Auger recombination in InGaN, beginning with the early work from 2007 and then considering additional work from more recent efforts to better understand the details behind this loss mechanism. [4pt] [1] Y. C. Shen, G. O. M"uller, S. Watanabe, N. F. Gardner, A. Munkholm, and M. R. Krames, ``Auger recombination in InGaN measured by photoluminescence'', Appl. Phys. Lett. 91, 141101 (2007). [0pt] [2] N. F. Gardner, G. O. M"uller, Y. C. Shen, G. Chen, S. Watanabe, W. G"otz, and M. R. Krames, ``Blue-emitting InGaN--GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm^2'', Appl. Phys. Lett. 91, 243506 (2007).

  20. Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes

    PubMed Central

    Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

    2015-01-01

    Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100–270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies. PMID:26568414

  1. Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes.

    PubMed

    Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

    2015-01-01

    Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100-270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies. PMID:26568414

  2. Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

    2015-11-01

    Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100-270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies.

  3. NREL preprints for the 23rd IEEE Photovoltaic Specialists Conference

    SciTech Connect

    Fitzgerald, M.

    1993-05-01

    Topics covered include various aspects of solar cell fabrication and performance. Aluminium-gallium arsenides, cadmium telluride, amorphous silicon, and copper-indium-gallium selenides are all characterized in their applicability in solar cells.

  4. Electrodeposition of gallium for photovoltaics

    DOEpatents

    Bhattacharya, Raghu N.

    2016-08-09

    An electroplating solution and method for producing an electroplating solution containing a gallium salt, an ionic compound and a solvent that results in a gallium thin film that can be deposited on a substrate.

  5. Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing

    NASA Astrophysics Data System (ADS)

    Alur, Siddharth

    Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

  6. Incorporation and diffusion of dopants in gallium arsenide, indium phosphide and indium gallium arsenide: Implications for devices

    NASA Astrophysics Data System (ADS)

    Tandon, Ashish

    Incorporation and diffusion of dopants in the InP, InGaAs and GaAs material systems by atmospheric pressure organometallic vapor phase epitaxy (APOMVPE) is discussed. A better understanding of the role point defect mechanisms play in driving dopant diffusion in III-V compounds has been obtained from experimental results. A study of Fermi level pinning at the surface of InP, InGaAs and GaAs is presented to explain the anomalously fast diffusion of dopants (such as Zn and Be which reside on the group III sublattice) observed in the base region of InP/InGaAs HBTs. Experimental results indicated that the Fermi level is not pinned at the surface of InGaAs while it appears to be pinned close to the valence band in InP. The Fermi level pinning at the surface of GaAs was found to vary with the crystal orientation. A solution to the problem of obtaining p-type base in InP/InGaAs HBTs has been presented in the form of carbon doped (p-type) InGaAs. The effects of growth temperature, V/III ratio and dopant source partial pressure on the concentration and mobility of holes in carbon doped InGaAs epilayers are reported. Record doping levels with negligible dopant passivation have been attained for carbon doped InGaAs epilayers. Studies linking dopant passivation to macroscopic defect formation are presented. A culmination of these findings in the growth and fabrication of InP/InGaAs HBTs with low base resistance and moderate gains is reported. A design resulting in the improvement of the collector-base breakdown voltage in InGaAs diodes is also discussed. The chemical treatment and history of the substrate were shown to play an important role in the diffusion of dopants in grown epilayers. Chlorine based compounds, thermal oxidation of the surface and growth of buffer layers (between the substrate and the epilayer) reduced diffusion in the epilayer. Sodium based compounds and anodic oxides tend to enhance dopant diffusion in the epilayer. A theoretical model for calculating dopant profiles has been developed and the simulated results show good agreement with experimental data. The model accounts for charged point defects, electric fields and Fermi level pinning at the surface.

  7. Characterization and Modeling of Indium Gallium Antimonide Avalanche Photodiode and of Indium Gallium Arsenide Two-band Detector

    NASA Technical Reports Server (NTRS)

    2006-01-01

    A model of the optical properties of Al(x)Ga(1-x)As(y)Sb(1-y) and In(x)Ga(1-x)As(y)Sb(1-y) is presented, including the refractive, extinction, absorption and reflection coefficients in terms of the optical dielectric function of the materials. Energy levels and model parameters for each binary compound are interpolated to obtain the needed ternaries and quaternaries for various compositions. Bowing parameters are considered in the interpolation scheme to take into account the deviation of the calculated ternary and quaternary values from experimental data due to lattice disorders. The inclusion of temperature effects is currently being considered.

  8. Chemical mechanical polishing of Indium phosphide, Gallium arsenide and Indium gallium arsenide films and related environment and safety aspects

    NASA Astrophysics Data System (ADS)

    Matovu, John Bogere

    As scaling continues with advanced technology nodes in the microelectronic industry to enhance device performance, the performance limits of the conventional substrate materials such as silicon as a channel material in the front-end-of-the-line of the complementary metal oxide semiconductor (CMOS) need to be surmounted. These challenges have invigorated research into new materials such as III-V materials consisting of InP, GaAs, InGaAs for n-channel CMOS and Ge for p-channels CMOS to enhance device performance. These III-V materials have higher electron mobility that is required for the n-channel while Ge has high hole mobility that is required for the p-channel. Integration of these materials in future devices requires chemical mechanical polishing (CMP) to achieve a smooth and planar surface to enable further processing. The CMP process of these materials has been associated with environment, health and safety (EH&S) issues due to the presence of P and As that can lead to the formation of toxic gaseous hydrides. The safe handling of As contaminated consumables and post-CMP slurry waste is essential. In this work, the chemical mechanical polishing of InP, GaAs and InGaAs films and the associated environment, health and safety (EH&S) issues are discussed. InP removal rates (RRs) and phosphine generation during the CMP of blanket InP films in hydrogen peroxide-based silica particle dispersions in the presence and absence of three different multifunctional chelating carboxylic acids, namely oxalic acid, tartaric acid, and citric acid are reported. The presence of these acids in the polishing slurry resulted in good InP removal rates (about 400 nm min-1) and very low phosphine generation (< 15 ppb) with very smooth post-polish surfaces (0.1 nm RMS surface roughness). The optimized slurry compositions consisting of 3 wt % silica, 1 wt % hydrogen peroxide and 0.08 M oxalic acid or citric acid that provided the best results on blanket InP films were used to evaluate their planarization capability of patterned InP-STI structures of 200 mm diameter wafers. Cross sectional scanning electron microscope (SEM) images showed that InP in the shallow trench isolation structures was planarized and scratches, slurry particles and smearing of InP were absent. Additionally, wafers polished at pH 6 showed very low dishing values of about 12-15 nm, determined by cross sectional SEM. During the polishing of blanket GaAs, GaAs RRs were negligible with deionized water or with silica slurries alone. They were relatively high in aq. solutions of H2O2 alone and showed a strong pH dependence, with significantly higher RRs in the alkaline region. The addition of silica particles to aq. H2O2 did not increase the GaAs RRs significantly. The evolution of arsenic trihydride (AsH3) during the dissolution of GaAs in aq. H2O2 solution was similarly higher in the basic pH range than in neutral pH or in the acidic pH range. However, no AsH3 was measured during polishing, evidently because of the relatively high water solubility of AsH3. The work done on InGaAs polishing shows that InGaAs RR trends are different from those observed for InP or GaAs. InGaAs RRs at pH 2 are higher than those at pH 10 and highest at pH 4. Dissolution rates (DRs), Fourier Transform Infrared Spectroscopy (FTIR), contact angles, X-Ray Photoelectron Spectroscopy (XPS), X-Ray Fluorescence Spectroscopy (XRF), zeta potential measurements and calculated Gibbs free energy changes of the reactions involved during polishing and gas formation were used to discuss the observed RRs and hydride gas generation trends and to propose the reaction pathways involved in the material removal and in hydride gas generation mechanisms.

  9. Synthesis of indium phosphide

    NASA Astrophysics Data System (ADS)

    Adamski, Joseph A.

    1983-11-01

    Polycrystalline ingots of indium phosphide have been synthesized using the direct reaction technique. Indium phosphide has been grown under various phosphorus pressures (3 to 30 atm). Several temperature profiles were used to study the effect of temperature on mobility, carrier concentration, grain size, homogeneity, and stoichiometry. Quartz and pyrolytic boron nitride boats are used. Several experiments were performed placing the PBN and quartz boats inside born nitride and aluminum oxide tubes in an attempt to lower silicon contamination. In-situ vacuum baking of the raw indium charge has resulted in a significant improvement in the purity of the synthesized InP.

  10. Ultra-low threshold gallium nitride photonic crystal nanobeam laser

    SciTech Connect

    Niu, Nan Woolf, Alexander; Wang, Danqing; Hu, Evelyn L.; Zhu, Tongtong; Oliver, Rachel A.; Quan, Qimin

    2015-06-08

    We report exceptionally low thresholds (9.1 μJ/cm{sup 2}) for room temperature lasing at ∼450 nm in optically pumped Gallium Nitride (GaN) nanobeam cavity structures. The nanobeam cavity geometry provides high theoretical Q (>100 000) with small modal volume, leading to a high spontaneous emission factor, β = 0.94. The active layer materials are Indium Gallium Nitride (InGaN) fragmented quantum wells (fQWs), a critical factor in achieving the low thresholds, which are an order-of-magnitude lower than obtainable with continuous QW active layers. We suggest that the extra confinement of photo-generated carriers for fQWs (compared to QWs) is responsible for the excellent performance.

  11. [Indium lung disease].

    PubMed

    Nakano, Makiko; Omae, Kazuyuki

    2014-02-01

    "Indium lung" is a new occupational lung disease. The global demand for indium, the major material used in manufacturing flat-screen display panels, has skyrocketed since the 1990s (Japan comprises 85% of the worldwide demand). The first case was reported in Japan in 2003, followed by seven cases (interstitial pneumonia and emphysema) in Japan. Two pulmonary alveolar proteinosis (PAP) cases in the USA followed in 2011. Indium lung has been described as interstitial pneumonia, pneumothorax, emphysema, and PAP. In 2013, The Japan Ministry of Health, Labor and Welfare issued an "Ordinance on the Prevention of Hazards Due to Specified Chemical Substances" requiring employers to provide regular health checks for employees and measurements of work environment concentrations of respirable indium dust.

  12. Effect of barrier height on friction behavior of the semiconductors silicon and gallium arsenide in contact with pure metals

    NASA Technical Reports Server (NTRS)

    Mishina, H.; Buckley, D. H.

    1984-01-01

    Friction experiments were conducted for the semiconductors silicon and gallium arsenide in contact with pure metals. Polycrystalline titanium, tantalum, nickel, palladium, and platinum were made to contact a single crystal silicon (111) surface. Indium, nickel, copper, and silver were made to contact a single crystal gallium arsenide (100) surface. Sliding was conducted both in room air and in a vacuum of 10 to the minus 9th power torr. The friction of semiconductors in contact with metals depended on a Schottky barrier height formed at the metal semiconductor interface. Metals with a higher barrier height on semiconductors gave lower friction. The effect of the barrier height on friction behavior for argon sputtered cleaned surfaces in vacuum was more specific than that for the surfaces containing films in room air. With a silicon surface sliding on titanium, many silicon particles back transferred. In contrast, a large quantity of indium transferred to the gallium arsenide surface.

  13. Indium gallium nitride/gallium nitride vacuum microelectronic cold cathodes: Piezoelectric surface barrier lowering

    NASA Astrophysics Data System (ADS)

    Underwood, Robert Douglas

    Vacuum microelectronic devices are electronic devices fabricated using microelectronic processing and using vacuum as a transport medium. The electron velocity in vacuum can be larger than in solid state, which allows higher frequency operation of vacuum devices compared to solid-state devices. The effectiveness of vacuum microelectronic devices relies on the realization of an efficient source of electrons supplied to the vacuum. Cold cathodes do not rely on thermal energy for the emission of electrons into vacuum. Cold cathodes based on field emission are the most common types of vacuum microelectronic cold cathode because they have a very high efficiency and high current density electron emission. Materials used to fabricate field emitters must have the properties of high electron concentration, low surface reactivity, resistance to sputtering by ions, high thermal conductivity, and a method of fabrication of uniform arrays of field emitters. The III--V nitride semiconductors possess these material properties and uniform arrays of GaN field emitter pyramids have been produced by selective area, self-limited metalorganic chemical vapor deposition. The first GaN field emitter arrays were fabricated and measured. Emission currents as large as 82 muA at 1100 V from 245,000 pyramids have been realized using an external anode, separated by 0.25 mm, to apply voltage bias. The operation voltage was reduced by the development of an integrated anode structure. The anode-cathode separation achievable with the integrated anode was in the range of 0.5--2.4 m. The turn-on voltages of these devices were reduced to the range of 175--435 V. The operation voltage of field emitter cathodes is related to the surface energy barrier, which for n-type semiconductors is the electron affinity. A new method to reduce the effective electron affinity using a piezoelectric dipole in an InGaN/GaN heterostructure has been proposed and tested. The piezoelectric field produced in the strained InGaN layer on a GaN pyramid produces a dipole that counteracts the surface barrier. The reduced barrier is characterized by defining an effective electron affinity. Emission results of InGaN/GaN field emitter arrays have shown a reduced electron affinity as low as 1.0 eV when compared to the electron affinity of GaN (3.5eV).

  14. Growth and fabrication of gallium nitride and indium gallium nitride-based optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Berkman, Erkan Acar

    In this study, heteroepitaxial growth of III-Nitrides was performed by metalorganic chemical vapor deposition (MOCVD) technique on (0001) Al 2O3 substrates to develop GaN and InxGa1-x N based optoelectronic devices. Comprehensive experimental studies on emission and relaxation mechanisms of InxGa1-xN quantum wells (QWs) and InxGa 1-xN single layers were performed. The grown films were characterized by x-ray diffraction (XRD), Hall Effect measurements, photoluminescence measurements (PL) and transmission electron microscopy (TEM). An investigation on the effect of number and width of QWs on PL emission properties of InxGa 1-xN single QWs and multi-quantum wells (MQW) was conducted. The experimental results were explained by the developed theoretical bandgap model. The study on the single layer InxGa1-xN films within and beyond critical layer thickness (CLT) demonstrated that thick InxGa 1-xN films display simultaneous presence of strained and (partially) relaxed layers. The In incorporation into the lattice was observed to be dependent on the strain state of the film. The findings on InxGa1-xN QWs and single layers were implemented in the development of InxGa1-xN based LEDs and photodiodes, respectively. The as-grown samples were fabricated using conventional lithography techniques into various optoelectronic devices including long wavelength LEDs, dichromatic monolithic white LEDs, and p-i-n photodiodes. Emission from InxGa1-xN/GaN MQW LEDs at wavelengths as long as 625nm was demonstrated. This is one of the longest peak emission wavelengths reported for MOCVD grown InxGa1-xN MQW structures. Dichromatic white emission in LEDs was realized by utilizing two InGaN MQW active regions emitting at complementary wavelengths. InGaN p-i-n photodiodes operating at various regions of the visible spectrum tailored by the i-layer properties were developed. This was achieved by the novel approach of employing InxGa1-xN in all layers of the p-i-n photodiodes, enabling nearly-lattice matched growth. The photodiodes displayed zero-bias responsivity values as high as 0.037A/W, and the peak responsivity wavelength of the photodiodes ranged between 416nm and 466nm. To the author's best knowledge, the latter value remains the longest peak detection wavelength among InxGa1-xN based p-i-n photodiodes.

  15. Micro and nano-structured green gallium indium nitride/gallium nitride light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Stark, Christoph J. M.

    Light-emitting diodes (LEDs) are commonly designed and studied based on bulk material properties. In this thesis different approaches based on patterns in the nano and micrometer length scale range are used to tackle low efficiency in the green spectral region, which is known as “green gap”. Since light generation and extraction are governed by microscopic processes, it is instructive to study LEDs with lateral mesa sizes scaled to the nanometer range. Besides the well-known case of the quantum size effect along the growth direction, a continuous lateral scaling could reveal the mechanisms behind the purported absence of a green gap in nanowire LEDs and the role of their extraction enhancement. Furthermore the possibility to modulate strain and piezoelectric polarization by post growth patterning is of practical interest, because the internal electric fields in conventional wurtzite GaN LEDs cause performance problems. A possible alternative is cubic phase GaN, which is free of built-in polarization fields. LEDs on cubic GaN could show the link between strong polarization fields and efficiency roll-off at high current densities, also known as droop. An additional problem for all nitride-based LEDs is efficient light extraction. For a planar GaN LED only roughly 8% of the generated light can be extracted. Novel lightextraction structures with extraction-favoring geometry can yield significant increase in light output power. To investigate the effect of scaling the mesa dimension, micro and nano-sized LED arrays of variable structure size were fabricated. The nano-LEDs were patterned by electron beam lithography and dry etching. They contained up to 100 parallel nano-stripe LEDs connected to one common contact area. The mesa width was varied over 1 μm, 200 nm, and 50 nm. These LEDs were characterized electrically and optically, and the peak emission wavelength was found to depend on the lateral structure size. An electroluminescence (EL) wavelength shift of 3 nm towards smaller values was observed when the stripe width was reduced from 1 μm to 50 nm. At the same time a strong fourfold enhancement of the light emission from the patterned region over the unpatterned area was observed. Micro-patterned LEDs showed non-linear scaling of the light output power, and an enhancement of 39 % was achieved for structures with an area fill ratio of 0.5 over an LED with square mesa. Growth of cubic GaN and cubic GaInN/GaN LEDs was shown by M-OVPE in Vshaped grooves formed by the {111} planes of etched silicon. SEM images of the GaN layer in small ( 0.5 μm) regions show a contrast change where the phase boundary between cubic and wurtzite GaN is expected to occur. The growth parameter space is explored for optimal conditions while minimizing the alloying problem for GaN growth on Si. The cubic GaN phase is confirmed by electron back-scatter diffraction (EBSD) in the V-groove center, whereas wurtzite GaN is found near the groove edges. Luminescence of undoped GaN and GaInN/GaN multi-quantum well structures was studied by cathodoluminescence (CL). The undoped cubic GaN structure showed strong band-edge luminescence at 385 nm (3.22 eV) at 78 K, whereas for the MQW device strong emission at 498 nm is observed, even at room temperature. Full cubic LED structures were grown, and wavelength-stable electroluminescence at 489 nm was demonstrated. LEDs with integrated light extraction structures are grown on free-standing GaN substrates with different off-cut angles. The devices with different off-cut show pronounced features at the top surface that also penetrate the active region. For a 2.24° off-cut, these features resemble fish scales, where the feature sizes are in the μm-range. The 2.24° off-cut LED shows a 3.6-fold increased light output power compared to a LED on virtually on-axis substrate with 0.06° off-cut. The enhancement found in the fish scale LEDs is attributed to increased light scattering, effectively reducing the fraction of trapped light. These results show the potential of structures on the micro and nanometer scale for LED device performance and the progress on cubic GaN could open alternative ways to understand the droop problem.

  16. Nanoscale optical properties of indium gallium nitride/gallium nitride nanodisk-in-rod heterostructures.

    PubMed

    Zhou, Xiang; Lu, Ming-Yen; Lu, Yu-Jung; Jones, Eric J; Gwo, Shangjr; Gradečak, Silvija

    2015-03-24

    III-nitride based nanorods and nanowires offer great potential for optoelectronic applications such as light emitting diodes or nanolasers. We report nanoscale optical studies of InGaN/GaN nanodisk-in-rod heterostructures to quantify uniformity of light emission on the ensemble level, as well as the emission characteristics from individual InGaN nanodisks. Despite the high overall luminescence efficiency, spectral and intensity inhomogeneities were observed and directly correlated to the compositional variations among nanodisks and to the presence of structural defect, respectively. Observed light quenching is correlated to type I1 stacking faults in InGaN nanodisks, and the mechanisms for stacking fault induced nonradiative recombinations are discussed in the context of band structure around stacking faults and Fermi level pinning at nanorod surfaces. Our results highlight the importance of controlling III-nitride nanostructure growths to further reduce defect formation and ensure compositional homogeneity for optoelectronic devices with high efficiencies and desirable spectrum response.

  17. Indium-111 labeled leukocytes in the evaluation of suspected abdominal abscesses.

    PubMed

    Coleman, R E; Black, R E; Welch, D M; Maxwell, J G

    1980-01-01

    Sixty-eight indium-111-labeled leukocyte imaging studies were performed in 53 patients with suspected abdominal abscesses. Twenty-nine studies gave abnoramal results. Nine wound infections were demonstrated, and 14 abscesses were correctly identified. Four studied demonstrated colonic accumulation, one of which remains unexplained, and two accessory spleens were identified. Indium-111 leukocyte imaging is a sensitive and specific study in evaluating patients with suspected abdominal abscess. Differentiation of abscess from other causes of inflammation has not been a problem. The exact role of leukocyte imaging compared with gallium-67 citrate imaging, ultrasound and computerized tomography remains to be determined.

  18. [Health effects of solar cell component material. Toxicity of indium compounds to laboratory animals determined by intratracheal instillations].

    PubMed

    Tanaka, Akiyo; Hirata, Miyuki

    2013-01-01

    Owing to the increasing interest being paid to the issue of the global environment, the production of solar cells has increased rapidly in recent years. Copper indium gallium diselenide (CIGS) is a new efficient thin film used in some types of solar cell. Indium is a constitutive element of CIGS thin-film solar cells. It was thought that indium compounds were not harmful until the beginning of the 1990s because there was little information regarding the adverse health effects on humans or animals arising from exposure to indium compounds. After the mid-1990s, data became available indicating that indium compounds can be toxic to animals. In animal studies, it has been clearly demonstrated that indium compounds cause pulmonary toxicity and that the dissolution of indium compounds in the lungs is considerably slow, as shown by repeated intratracheal instillations in experimental animals. Thus, it is necessary to pay much greater attention to human exposure to indium compounds, and precautions against possible exposure to indium compounds are paramount with regard to health management.

  19. Gallium-containing anticancer compounds.

    PubMed

    Chitambar, Christopher R

    2012-06-01

    There is an ever pressing need to develop new drugs for the treatment of cancer. Gallium nitrate, a group IIIa metal salt, inhibits the proliferation of tumor cells in vitro and in vivo and has shown activity against non-Hodgkin's lymphoma and bladder cancer in clinical trials. Gallium can function as an iron mimetic and perturb iron-dependent proliferation and other iron-related processes in tumor cells. Gallium nitrate lacks crossresistance with conventional chemotherapeutic drugs and is not myelosuppressive; it can be used when other drugs have failed or when the blood count is low. Given the therapeutic potential of gallium, newer generations of gallium compounds are now in various phases of preclinical and clinical development. These compounds hold the promise of greater anti-tumor activity against a broader spectrum of cancers. The development of gallium compounds for cancer treatment and their mechanisms of action will be discussed.

  20. Indium Lung Disease

    PubMed Central

    Nakano, Makiko; Omae, Kazuyuki; Takeuchi, Koichiro; Chonan, Tatsuya; Xiao, Yong-long; Harley, Russell A.; Roggli, Victor L.; Hebisawa, Akira; Tallaksen, Robert J.; Trapnell, Bruce C.; Day, Gregory A.; Saito, Rena; Stanton, Marcia L.; Suarthana, Eva; Kreiss, Kathleen

    2012-01-01

    Background: Reports of pulmonary fibrosis, emphysema, and, more recently, pulmonary alveolar proteinosis (PAP) in indium workers suggested that workplace exposure to indium compounds caused several different lung diseases. Methods: To better understand the pathogenesis and natural history of indium lung disease, a detailed, systematic, multidisciplinary analysis of clinical, histopathologic, radiologic, and epidemiologic data for all reported cases and workplaces was undertaken. Results: Ten men (median age, 35 years) who produced, used, or reclaimed indium compounds were diagnosed with interstitial lung disease 4-13 years after first exposure (n = 7) or PAP 1-2 years after first exposure (n = 3). Common pulmonary histopathologic features in these patients included intraalveolar exudate typical of alveolar proteinosis (n = 9), cholesterol clefts and granulomas (n = 10), and fibrosis (n = 9). Two patients with interstitial lung disease had pneumothoraces. Lung disease progressed following cessation of exposure in most patients and was fatal in two. Radiographic data revealed that two patients with PAP subsequently developed fibrosis and one also developed emphysematous changes. Epidemiologic investigations demonstrated the potential for exposure to respirable particles and an excess of lung abnormalities among coworkers. Conclusions: Occupational exposure to indium compounds was associated with PAP, cholesterol ester crystals and granulomas, pulmonary fibrosis, emphysema, and pneumothoraces. The available evidence suggests exposure to indium compounds causes a novel lung disease that may begin with PAP and progress to include fibrosis and emphysema, and, in some cases, premature death. Prospective studies are needed to better define the natural history and prognosis of this emerging lung disease and identify effective prevention strategies. PMID:22207675

  1. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon

    2015-04-01

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na2CO3, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na2CO3, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4M HCl, 100°C and pulp density of 20g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching.

  2. Molecular Beam Epitaxial Growth and Characterization of Mismatched Indium Gallium Arsenide and Indium Aluminum Arsenide Layers on Indium Phosphide

    NASA Astrophysics Data System (ADS)

    Bennett, Brian R.

    Mismatched epitaxial layers of In_ {x}Ga_{1-x}As and In_{y}Al_ {1-y}As were grown on (001) InP by molecular beam epitaxy. The layers were characterized by a technique we developed known as variable azimuthal-angle ellipsometry. It reveals large optical anisotropy for many strained layers. We attribute the anisotropy to strain-induced surface roughening during growth. Samples were also characterized by high -resolution x-ray diffraction (HRXRD) to assess layer quality as well as composition and strain. HRXRD measurements reveal orthorhombic distortion of partially relaxed layers of InGaAs and InAlAs in tension or compression, with preferential strain relief in the (110) direction. We show that HRXRD epilayer peak width and interference fringes are sensitive, non-destructive criteria to judge the structural quality of strained heterostructures. For layers ranging from 300 to 10,000 A, with lattice mismatch of +/- 1% or less, the crystalline quality consistently remains high to thicknesses up to 3-9 times the Matthews -Blakeslee critical layer thickness. We investigated the thermal stability of these layers, using HRXRD to measure structural changes caused by high-temperature anneals. We also compared the electron mobility of modulation-doped heterostructures before and after annealing. Both techniques demonstrate that our high-quality strained layers are stable to temperatures of at least 800-850^circ C. We explain this result by the limited sources available for the nucleation of misfit dislocations. The findings are applied to the design and growth of high-performance pseudomorphic InAlAs/InGaAs/InP heterostructure field-effect transistors with layers exceeding the Matthews-Blakeslee limit. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.).

  3. Gallium interactions with Zircaloy

    SciTech Connect

    Woods, A.L.; West, M.K.

    1999-01-01

    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.

  4. Indium droplet formation in InGaN thin films with single and double heterojunctions prepared by MOCVD

    NASA Astrophysics Data System (ADS)

    Chen, Yung-Sheng; Liao, Che-Hao; Kuo, Chie-Tong; Tsiang, Raymond Chien-Chao; Wang, Hsiang-Chen

    2014-07-01

    Indium gallium nitride (InGaN) samples with single heterojunction (SH) and double heterojunction (DH) were prepared using metal-organic chemical vapor deposition. SH has a layer of InGaN thin film (thicknesses, 25, 50, 100, and 200 nm) grown on an uGaN film (thickness, 2 μm). The DH samples are distinguished by DH uGaN film (thickness, 120 nm) grown on the InGaN layer. Reciprocal space mapping measurements reveal that the DH samples are fully strained with different thicknesses, whereas the strain in the SH samples are significantly relaxed with the increasing thickness of the InGaN film. Scanning electron microscopy results show that the surface roughness of the sample increases when the sample is relaxed. High-resolution transmission electron microscopy images of the structure of indium droplets in the DH sample indicate that the thickness of the InGaN layer decreases with the density of indium droplets. The formation of these droplets is attributed to the insufficient kinetic energy of indium atom to react with the elements of group V, resulting to aggregation. The gallium atoms in the GaN thin film will not be uniformly replaced by indium atoms; the InGaN thin film has an uneven distribution of indium atoms and the quality of the epitaxial layer is degraded.

  5. Fabrication methods and applications of microstructured gallium based liquid metal alloys

    NASA Astrophysics Data System (ADS)

    Khondoker, M. A. H.; Sameoto, D.

    2016-09-01

    This review contains a comparative study of reported fabrication techniques of gallium based liquid metal alloys embedded in elastomers such as polydimethylsiloxane or other rubbers as well as the primary challenges associated with their use. The eutectic gallium-indium binary alloy (EGaIn) and gallium-indium-tin ternary alloy (galinstan) are the most common non-toxic liquid metals in use today. Due to their deformability, non-toxicity and superior electrical conductivity, these alloys have become very popular among researchers for flexible and reconfigurable electronics applications. All the available manufacturing techniques have been grouped into four major classes. Among them, casting by needle injection is the most widely used technique as it is capable of producing features as small as 150 nm width by high-pressure infiltration. One particular fabrication challenge with gallium based liquid metals is that an oxide skin is rapidly formed on the entire exposed surface. This oxide skin increases wettability on many surfaces, which is excellent for keeping patterned metal in position, but is a drawback in applications like reconfigurable circuits, where the position of liquid metal needs to be altered and controlled accurately. The major challenges involved in many applications of liquid metal alloys have also been discussed thoroughly in this article.

  6. Indium sealing techniques.

    NASA Technical Reports Server (NTRS)

    Hochuli, U.; Haldemann, P.

    1972-01-01

    Gold films are used as an alloying flux to form 5-micron-thick indium film seals at temperatures below 300 C. Pyrex was sealed to quartz, ULE, CER-VIT, Irtran 2, Ge, GaAs, Invar, Kovar, Al, and Cu. The seals can also be used as current feedthroughs and graded seals.

  7. Field-effect transistors based on cubic indium nitride

    PubMed Central

    Oseki, Masaaki; Okubo, Kana; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2014-01-01

    Although the demand for high-speed telecommunications has increased in recent years, the performance of transistors fabricated with traditional semiconductors such as silicon, gallium arsenide, and gallium nitride have reached their physical performance limits. Therefore, new materials with high carrier velocities should be sought for the fabrication of next-generation, ultra-high-speed transistors. Indium nitride (InN) has attracted much attention for this purpose because of its high electron drift velocity under a high electric field. Thick InN films have been applied to the fabrication of field-effect transistors (FETs), but the performance of the thick InN transistors was discouraging, with no clear linear-saturation output characteristics and poor on/off current ratios. Here, we report the epitaxial deposition of ultrathin cubic InN on insulating oxide yttria-stabilized zirconia substrates and the first demonstration of ultrathin-InN-based FETs. The devices exhibit high on/off ratios and low off-current densities because of the high quality top and bottom interfaces between the ultrathin cubic InN and oxide insulators. This first demonstration of FETs using a ultrathin cubic indium nitride semiconductor will thus pave the way for the development of next-generation high-speed electronics. PMID:24492240

  8. Field-effect transistors based on cubic indium nitride.

    PubMed

    Oseki, Masaaki; Okubo, Kana; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2014-02-04

    Although the demand for high-speed telecommunications has increased in recent years, the performance of transistors fabricated with traditional semiconductors such as silicon, gallium arsenide, and gallium nitride have reached their physical performance limits. Therefore, new materials with high carrier velocities should be sought for the fabrication of next-generation, ultra-high-speed transistors. Indium nitride (InN) has attracted much attention for this purpose because of its high electron drift velocity under a high electric field. Thick InN films have been applied to the fabrication of field-effect transistors (FETs), but the performance of the thick InN transistors was discouraging, with no clear linear-saturation output characteristics and poor on/off current ratios. Here, we report the epitaxial deposition of ultrathin cubic InN on insulating oxide yttria-stabilized zirconia substrates and the first demonstration of ultrathin-InN-based FETs. The devices exhibit high on/off ratios and low off-current densities because of the high quality top and bottom interfaces between the ultrathin cubic InN and oxide insulators. This first demonstration of FETs using a ultrathin cubic indium nitride semiconductor will thus pave the way for the development of next-generation high-speed electronics.

  9. Oxidative dissolution of gallium arsenide and separation of gallium from arsenic

    SciTech Connect

    Coleman, J.P.; Monzyk, B.F.

    1988-07-26

    The method of dissociating gallium arsenide into a gallium-containing component and an arsenic-containing component, is described which comprises contacting the gallium arsenide with an oxidizing agent and a liquid comprising hydroxamic acid to convert the gallium to a gallium-hydroxamic acid complex and to oxidize the arsenic to a positive valence state.

  10. Gallium--A smart metal

    USGS Publications Warehouse

    Foley, Nora; Jaskula, Brian W.

    2013-01-01

    Gallium is a soft, silvery metallic element with an atomic number of 31 and the chemical symbol Ga. The French chemist Paul-Emile Lecoq de Boisbaudran discovered gallium in sphalerite (a zinc-sulfide mineral) in 1875 using spectroscopy. He named the element "gallia" after his native land of France (formerly Gaul; in Latin, Gallia). The existence of gallium had been predicted in 1871 by Dmitri Mendeleev, the Russian chemist who published the first periodic table of the elements. Mendeleev noted a gap in his table and named the missing element "eka-aluminum" because he determined that its location was one place away from aluminum in the table. Mendeleev thought that the missing element (gallium) would be very much like aluminum in its chemical properties, and he was right. Solid gallium has a low melting temperature (~29 degrees Celsius, or °C) and an unusually high boiling point (~2,204 °C). Because of these properties, the earliest uses of gallium were in high-temperature thermometers and in designing metal alloys that melt easily. The development of a gallium-based direct band-gap semiconductor in the 1960s led to what is now one of the most well-known applications for gallium-based products--the manufacture of smartphones and data-centric networks.

  11. Indium-doped GaAs: Investigation of deep traps

    NASA Astrophysics Data System (ADS)

    Laurenti, J. P.; Wolter, K.; Roentgen, P.; Seibert, K.; Kurz, H.; Camassel, J.

    1989-03-01

    The effect of indium incorporation on the concentration of deep traps in a series of GaAs epitaxial layers has been investigated by performing quantitative photoluminescence (PL) and capacitance [deep-level transient spectroscopy (DLTS)] spectroscopic studies. All samples were epitaxial layers of n-type GaAs:In, grown by organometallic vapor-phase epitaxy (OMVPE) on liquid-encapsulated Czochralski (LEC) -grown GaAs:Cr substrates. The calibrated indium concentration ranged between 0 and 6.5×1019 atoms cm-3, which is about 0.3% in alloy composition. We have investigated (i) the bands associated with chromium in both the epitaxial layers and the original substrates; (ii) a large recombination band, associated with an unidentified (D-VGa) complex, at about 1.2 eV; and (iii) the DLTS signal associated with the well-known deep trap EL2. We find the following. First, there is a one-to-one correspondence between the PL intensity associated with Cr2+, at 0.84 eV, and the D-VGa signal at 1.2 eV. This is true for both the epitaxial layers and the original substrates and suggests identification of the unknown donor participating in the D-VGa complex as Cr4+. Second, we find all PL intensities to decrease with increasing indium concentration, while the concentration and depth profile of EL2 are not affected. In contrast to the near-band-edge PL intensity, which increased with increasing indium content, there is a drop by about 1 order of magnitude for all chromium-related features when going from indium-free to about 0.3% indium-rich sample. Moreover, there is a one-to-one correspondence between the increase in the near-band-edge PL intensity and the decrease in the chromium-related signals. This establishes, on a fully experimental basis, the relative roles played by indium and chromium in our epitaxial samples: both compete to incorporate on gallium sites in the strain field of neighboring vacancies but, because of a higher incorporation rate, increasing the indium

  12. Respirable Indium Exposures, Plasma Indium, and Respiratory Health Among Indium-Tin Oxide (ITO) Workers

    PubMed Central

    Cummings, Kristin J.; Virji, M. Abbas; Park, Ji Young; Stanton, Marcia L.; Edwards, Nicole T.; Trapnell, Bruce C.; Carey, Brenna; Stefaniak, Aleksandr B.; Kreiss, Kathleen

    2016-01-01

    Background Workers manufacturing indium-tin oxide (ITO) are at risk of elevated indium concentration in blood and indium lung disease, but relationships between respirable indium exposures and biomarkers of exposure and disease are unknown. Methods For 87 (93%) current ITO workers, we determined correlations between respirable and plasma indium and evaluated associations between exposures and health outcomes. Results Current respirable indium exposure ranged from 0.4 to 108 μg/m3 and cumulative respirable indium exposure from 0.4 to 923 μg-yr/m3. Plasma indium better correlated with cumulative (rs = 0.77) than current exposure (rs = 0.54) overall and with tenure ≥1.9 years. Higher cumulative respirable indium exposures were associated with more dyspnea, lower spirometric parameters, and higher serum biomarkers of lung disease (KL-6 and SP-D), with significant effects starting at 22 μg-yr/m3, reached by 46% of participants. Conclusions Plasma indium concentration reflected cumulative respirable indium exposure, which was associated with clinical, functional, and serum biomarkers of lung disease. PMID:27219296

  13. Indium Sorption to Iron Oxides

    NASA Astrophysics Data System (ADS)

    White, S. J.; Sacco, S. A.; Hemond, H.; Hussain, F. A.; Runkel, R. L.; Walton-Day, K. E.; Kimball, B. A.; Shine, J. P.

    2014-12-01

    Indium is an increasingly important metal in semiconductors and electronics, and its use is growing rapidly as a semiconductive coating (as indium tin oxide) for liquid crystal displays (LCDs) and flat panel displays. It also has uses in important energy technologies such as light emitting diodes (LEDs) and photovoltaic cells. Despite its rapid increase in use, very little is known about the environmental behavior of indium, and concerns are being raised over the potential health effects of this emerging metal contaminant. One source of indium to the environment is acid mine drainage from the mining of lead, zinc, and copper sulfides. In our previous studies of a stream in Colorado influenced by acid mine drainage from lead and zinc mining activities, indium concentrations were found to be 10,000 times those found in uncontaminated rivers. However, the speciation and mobility of indium could not be reliably modeled because sorption constants to environmental sorbents have not been determined. In this study, we generate sorption constants for indium to ferrihydrite in the laboratory over a range of pHs, sorbent to sorbate ratios, and ionic strengths. Ferrihydrite is one of the most important sorbents in natural systems, and sorption to amorphous iron oxides such as ferrihydrite is thought to be one of the main removal mechanisms of metals from the dissolved phase in aqueous environments. Because of its relatively low solubility, we also find that indium hydroxide precipitation can dominate indium's partitioning at micromolar concentrations of indium. This precipitation may be important in describing indium's behavior in our study stream in Colorado, where modeling sorption to iron-oxides does not explain the complete removal of indium from the dissolved phase when the pH of the system is artificially raised to above 8. This study contributes much-needed data about indium's aqueous behavior, in order to better understand its fate, transport, and impacts in the

  14. Gallium nitride nanotube lasers

    SciTech Connect

    Li, Changyi; Liu, Sheng; Hurtado, Antonio; Wright, Jeremy Benjamin; Xu, Huiwen; Luk, Ting Shan; Figiel, Jeffrey J.; Brener, Igal; Brueck, Steven R. J.; Wang, George T.

    2015-01-01

    Lasing is demonstrated from gallium nitride nanotubes fabricated using a two-step top-down technique. By optically pumping, we observed characteristics of lasing: a clear threshold, a narrow spectral, and guided emission from the nanotubes. In addition, annular lasing emission from the GaN nanotube is also observed, indicating that cross-sectional shape control can be employed to manipulate the properties of nanolasers. The nanotube lasers could be of interest for optical nanofluidic applications or application benefitting from a hollow beam shape.

  15. Gallium Arsenide Domino Circuit

    NASA Technical Reports Server (NTRS)

    Yang, Long; Long, Stephen I.

    1990-01-01

    Advantages include reduced power and high speed. Experimental gallium arsenide field-effect-transistor (FET) domino circuit replicated in large numbers for use in dynamic-logic systems. Name of circuit denotes mode of operation, which logic signals propagate from each stage to next when successive stages operated at slightly staggered clock cycles, in manner reminiscent of dominoes falling in a row. Building block of domino circuit includes input, inverter, and level-shifting substages. Combinational logic executed in input substage. During low half of clock cycle, result of logic operation transmitted to following stage.

  16. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

    1996-01-01

    Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

  17. Fundamental studies of the metallurgical, electrical, and optical properties of gallium phosphide and gallium phosphide alloys

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Abstracts, bibliographic data, oral presentations, and published papers on (1) Diffusion of Sulfur in Gallium Phosphide and Gallium Arsenide, and (2) Properties of Gallium Phosphide Schottky Barrier Rectifiers for Use at High Temperature are presented.

  18. Aluminium contamination from fluoride assisted dissolution of metallic aluminium.

    PubMed

    Tennakone, K; Wickramanayake, S; Fernando, C A

    1988-01-01

    Trace amounts (microg g(-1) quantities) of fluoride ion are found to catalyse the dissolution of metallic aluminium in very slightly acidic or alkaline aqueous media. Possibly hazardous levels of aluminium could get leached from cooking utensils if fluoridated water or fluoride rich foodstuffs are used. The fluoride assisted corrosion of aluminium is most dramatic in oxalic, tartaric acids or sodium bicarbonate. Carbon dioxide also corrodes aluminium in the presence of the fluoride ion, generating colloidal hydrated aluminium oxide which is readily soluble in dilute organic and mineral acids. PMID:15092668

  19. Electrospun Gallium Nitride Nanofibers

    SciTech Connect

    Melendez, Anamaris; Morales, Kristle; Ramos, Idalia; Campo, Eva; Santiago, Jorge J.

    2009-04-19

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

  20. Gallium interstitial contributions to diffusion in gallium arsenide

    NASA Astrophysics Data System (ADS)

    Schick, Joseph T.; Morgan, Caroline G.

    2011-09-01

    A new diffusion path is identified for gallium interstitials, which involves lower barriers than the barriers for previously identified diffusion paths [K. Levasseur-Smith and N. Mousseau, J. Appl. Phys. 103, 113502 (2008), P. A. Schultz and O. A. von Lilienfeld, Modelling and Simulation in Materials Science and Engineering 17, 084007 (2009)] for the charge states which dominate diffusion over most of the available range of Fermi energies. This path passes through the ⟨110⟩ gallium-gallium split interstitial configuration, and has a particularly low diffusion barrier of 0.35 eV for diffusion in the neutral charge state. As a part of this work, the character of the charge states for the gallium interstitials which are most important for diffusion is investigated, and it is shown that the last electron bound to the neutral interstitial occupies a shallow hydrogenic bound state composed of conduction band states for the hexagonal interstitial and both tetrahedral interstitials. How to properly account for the contributions of such interstitials is discussed for density-functional calculations with a k-point mesh not including the conduction band edge point. Diffusion barriers for gallium interstitials are calculated in all the charge states which can be important for a Fermi level anywhere in the gap, q = 0, +1, +2, and +3, for diffusion via the ⟨110⟩ gallium-gallium split interstitial configuration and via the hexagonal interstitial configuration. The lowest activation enthalpies over most of the available range of Fermi energies are found to correspond to diffusion in the neutral or singly positive state via the ⟨110⟩ gallium-gallium split interstitial configuration. It is shown that several different charge states and diffusion paths contribute significantly for Fermi levels within 0.2 eV above the valence band edge, which may help to explain some of the difficulties [H. Bracht and S. Brotzmann, Phys. Rev. B 71, 115216 (2005)] which have been

  1. Indium-doped GaAs: A very dilute alloy system

    NASA Astrophysics Data System (ADS)

    Laurenti, J. P.; Roentgen, P.; Wolter, K.; Seibert, K.; Kurz, H.; Camassel, J.

    1988-03-01

    The influence of indium incorporation in GaAs organometallic-vapor-phase-epitaxy (OMVPE) layers has been investigated in great detail. The results obtained concern the change in band-gap energy, the concentration of residual impurities, and the low-temperature (2-K) photoluminescence (PL) efficiency. For In concentrations ranging between 0 and 6.5×1019 cm-3, both A0X and D0X bound-exciton lines could be resolved. Together with the near-band-gap transitions involving shallow impurities (DA- and eA-related recombination lines), they shift toward lower energies versus indium content. This indicates the formation of a ternary compound Ga1-xInxAs, even at these extremely dilute indium concentrations. After a quantitative calibration of the indium content, linear relations have been found which connect the PL emission line energies and the indium concentration. They make low-temperature PL measurements the most quantitative, and nondestructive, tool for precise composition studies. In this case, care should be taken that the slope parameters are line dependent. For instance, we find a slight, but finite, discrepancy between the slope parameters corresponding to substitutional acceptors on Ga and As sites, respectively. This is discussed in terms of the two different sublattices by using a simple cluster model of 17 atoms. Lastly, we find the absolute PL intensities to increase versus indium concentration: This indicates an improvement in the optical quality of our samples. Since, on a relative scale, the PL signals involving ZnGa and/or MgGa residual acceptors are not significantly affected by the amount of indium incorporated, but depend mainly on the growth sequence, we feel that indium in GaAs acts primarily by closing nonradiative-recombination paths which are not necessarily associated with gallium vacancies.

  2. Gallium Safety in the Laboratory

    SciTech Connect

    Lee C. Cadwallader

    2003-06-01

    A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

  3. Gallium Safety in the Laboratory

    SciTech Connect

    Cadwallader, L.C.

    2003-05-07

    A university laboratory experiment for the US Department of Energy magnetic fusion research program required a simulant for liquid lithium. The simulant choices were narrowed to liquid gallium and galinstan (Ga-In-Sn) alloy. Safety information on liquid gallium and galinstan were compiled, and the choice was made to use galinstan. A laboratory safety walkthrough was performed in the fall of 2002 to support the galinstan experiment. The experiment has been operating successfully since early 2002.

  4. Mineral of the month: indium

    USGS Publications Warehouse

    George, Micheal W.

    2004-01-01

    Indium was discovered in Germany in 1863. Although it is a lustrous silver-white color, the finders named the new material for the “indigo” spectral lines the mineral created on the spectrograph. Indium ranks 61st in abundance in Earth’s crust and is about three times more abundant than silver or mercury.

  5. Aluminium and human breast diseases.

    PubMed

    Darbre, P D; Pugazhendhi, D; Mannello, F

    2011-11-01

    The human breast is exposed to aluminium from many sources including diet and personal care products, but dermal application of aluminium-based antiperspirant salts provides a local long-term source of exposure. Recent measurements have shown that aluminium is present in both tissue and fat of the human breast but at levels which vary both between breasts and between tissue samples from the same breast. We have recently found increased levels of aluminium in noninvasively collected nipple aspirate fluids taken from breast cancer patients (mean 268 ± 28 μg/l) compared with control healthy subjects (mean 131 ± 10 μg/l) providing evidence of raised aluminium levels in the breast microenvironment when cancer is present. The measurement of higher levels of aluminium in type I human breast cyst fluids (median 150 μg/l) compared with human serum (median 6 μg/l) or human milk (median 25 μg/l) warrants further investigation into any possible role of aluminium in development of this benign breast disease. Emerging evidence for aluminium in several breast structures now requires biomarkers of aluminium action in order to ascertain whether the presence of aluminium has any biological impact. To this end, we report raised levels of proteins that modulate iron homeostasis (ferritin, transferrin) in parallel with raised aluminium in nipple aspirate fluids in vivo, and we report overexpression of mRNA for several S100 calcium binding proteins following long-term exposure of MCF-7 human breast cancer cells in vitro to aluminium chlorhydrate.

  6. Aluminium and human breast diseases.

    PubMed

    Darbre, P D; Pugazhendhi, D; Mannello, F

    2011-11-01

    The human breast is exposed to aluminium from many sources including diet and personal care products, but dermal application of aluminium-based antiperspirant salts provides a local long-term source of exposure. Recent measurements have shown that aluminium is present in both tissue and fat of the human breast but at levels which vary both between breasts and between tissue samples from the same breast. We have recently found increased levels of aluminium in noninvasively collected nipple aspirate fluids taken from breast cancer patients (mean 268 ± 28 μg/l) compared with control healthy subjects (mean 131 ± 10 μg/l) providing evidence of raised aluminium levels in the breast microenvironment when cancer is present. The measurement of higher levels of aluminium in type I human breast cyst fluids (median 150 μg/l) compared with human serum (median 6 μg/l) or human milk (median 25 μg/l) warrants further investigation into any possible role of aluminium in development of this benign breast disease. Emerging evidence for aluminium in several breast structures now requires biomarkers of aluminium action in order to ascertain whether the presence of aluminium has any biological impact. To this end, we report raised levels of proteins that modulate iron homeostasis (ferritin, transferrin) in parallel with raised aluminium in nipple aspirate fluids in vivo, and we report overexpression of mRNA for several S100 calcium binding proteins following long-term exposure of MCF-7 human breast cancer cells in vitro to aluminium chlorhydrate. PMID:22099158

  7. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  8. Metal Insulator Semiconductor Structures on Gallium Arsenide.

    NASA Astrophysics Data System (ADS)

    Connor, Sean Denis

    Available from UMI in association with The British Library. The compound semiconductor gallium arsenide and its associated aluminium alloys have been the subject of intensive research in recent years. These materials offer the advantage of high electron mobilities coupled with the ability to be 'barrier engineered' leading to high injection efficiencies in bipolar devices. From a technological viewpoint however these materials are difficult to work with and device realisation is a major problem. Both thermal and anodic oxidation of these materials fail to produce a dielectric of sufficient quality for device applications and as a result devices tend to be complex non planar, mesa structures. A technique is proposed whereby the electrical interface is separated from the dielectric by means of a thin layer of AlGaAs, carrier confinement in the active GaAs region being maintained by the potential barriers to holes and electrons formed by the GaAs-AlGaAs junction. The integrity of these barriers is maintained by the provision of a suitable 'capping' dielectric. The electrical characteristics of various dielectric systems on GaAs have been investigated by means of current -voltage, capacitance-voltage and electronic breakdown measurements. Transport mechanisms for leakage current through these systems are identified and the interface properties (viz Fermi level pinning etc.) assessed by means of a direct comparison between experimental capacitance-voltage curves and theoretical data obtained from classical theory. As a technique for producing a convenient, in house 'capping' dielectric with good electrical and mechanical properties, the plasma anodisation of deposited aluminium films has been investigated. The anodisation parameters have been optimised for oxidation of these films in a microwave sustained oxygen plasma to give alumina films of around 500 A. A qualitative model for the anodisation process, involving linear and parabolic growth kinetics is proposed and

  9. Aluminium contents in baked meats wrapped in aluminium foil.

    PubMed

    Turhan, Sadettin

    2006-12-01

    In this investigation, the effect of cooking treatments (60min at 150°C, 40min at 200°C, and 20min at 250°C) on aluminium contents of meats (beef, water buffalo, mutton, chicken and turkey) baked in aluminium foil were evaluated. Cooking increased the aluminium concentration of both the white and red meats. The increase was 89-378% in red meats and 76-215% in poultry. The least increase (76-115%) was observed in the samples baked for 60min at 150°C, while the highest increase (153-378%) was in samples baked for 20min at 250°C. It was determined that the fat content of meat in addition to the cooking process affected the migration of aluminium (r(2)=0.83; P<0.01). It was also found that raw chicken and turkey breast meat contained higher amounts of aluminium than the raw chicken and turkey leg meat, respectively. Regarding the suggested provisional tolerable daily intake of 1mg Al/kg body weight per day of the FAO/WHO Expert Committee on Food Additives, there are no evident risks to the health of the consumer from using aluminium foil to cook meats. However, eating meals prepared in aluminium foil may carry a risk to the health by adding to other aluminium sources.

  10. Medical applications and toxicities of gallium compounds.

    PubMed

    Chitambar, Christopher R

    2010-05-01

    Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use.

  11. Medical Applications and Toxicities of Gallium Compounds

    PubMed Central

    Chitambar, Christopher R.

    2010-01-01

    Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use. PMID:20623028

  12. A FETISH for gallium arsenide

    SciTech Connect

    Barron, A.R.

    1996-12-31

    An overview of the development of a new dielectric material, cubic-GaS, from the synthesis of new organometallic compounds to the fabrication of a new class of gallium arsenide based transistor is presented as a representative example of the possibility that inorganic chemistry can directly effect the development of new semiconductor devices. The gallium sulfido compound [({sup t}Bu)GaS]{sub 4}, readily prepared from tri-tert-butyl gallium, may be used as a precursor for the growth of GaS thin films by metal organic chemical vapor deposition (MOCVD). Photoluminescence and electronic measurements indicate that this material provides a passivation coating for GaAs. Furthermore, the insulating properties of cubic-GaS make it suitable as the insulating gate layer in a new class of GaAs transistor: a field effect transistor with a sulfide heterojunction (FETISH).

  13. Mineral resource of the month: gallium

    USGS Publications Warehouse

    Jaskula, Brian W.

    2009-01-01

    The metal element gallium occurs in very small concentrations in rocks and ores of other metals — native gallium is not known. As society gets more and more high-tech, gallium becomes more useful. Gallium is one of only five metals that are liquid at or close to room temperature. It has one of the longest liquid ranges of any metal (29.8 degrees Celsius to 2204 degrees Celsius) and has a low vapor pressure even at high temperatures. Ultra-pure gallium has a brilliant silvery appearance, and the solid metal exhibits conchoidal fracture similar to glass.

  14. Recycling of indium from CIGS photovoltaic cells: potential of combining acid-resistant nanofiltration with liquid-liquid extraction.

    PubMed

    Zimmermann, Yannick-Serge; Niewersch, Claudia; Lenz, Markus; Kül, Zöhre Zohra; Corvini, Philippe F-X; Schäffer, Andreas; Wintgens, Thomas

    2014-11-18

    Electronic consumer products such as smartphones, TV, computers, light-emitting diodes, and photovoltaic cells crucially depend on metals and metalloids. So-called "urban mining" considers them as secondary resources since they may contain precious elements at concentrations many times higher than their primary ores. Indium is of foremost interest being widely used, expensive, scarce and prone to supply risk. This study first investigated the capability of different nanofiltration membranes of extracting indium from copper-indium-gallium- selenide photovoltaic cell (CIGS) leachates under low pH conditions and low transmembrane pressure differences (<3 bar). Retentates were then subjected to a further selective liquid-liquid extraction (LLE). Even at very acidic pH indium was retained to >98% by nanofiltration, separating it from parts of the Ag, Sb, Se, and Zn present. LLE using di-(2-ethylhexyl)phosphoric acid (D2EHPA) extracted 97% of the indium from the retentates, separating it from all other elements except for Mo, Al, and Sn. Overall, 95% (2.4 g m(-2) CIGS) of the indium could be extracted to the D2EHPA phase. Simultaneously, by nanofiltration the consumption of D2EHPA was reduced by >60% due to the metal concentration in the reduced retentate volume. These results show clearly the potential for efficient scarce metal recovery from secondary resources. Furthermore, since nanofiltration was applicable at very low pH (≥ 0.6), it may be applied in hydrometallurgy typically using acidic conditions.

  15. Indium induced band gap tailoring in AgGa{sub 1-x}In{sub x}S{sub 2} chalcopyrite structure for visible light photocatalysis

    SciTech Connect

    Jang, Jum Suk; Borse, Pramod H.; Lee, Jae Sung; Choi, Sun Hee; Kim, Hyun Gyu

    2008-04-21

    Indium was substituted at gallium site in chalcopyrite AgGaS{sub 2} structure by using a simple solid solution method. The spectroscopic analysis using extended x-ray absorption fine structure and x-ray photoelectron spectroscopy confirmed the indium substitution in AgGaS{sub 2} lattice. The band gap energy of AgGa{sub 1-x}In{sub x}S{sub 2} (x=0-1) estimated from the onset of absorption edge was found to be reduced from 2.67 eV (x=0) to 1.9 eV (x=1) by indium substitution. The theoretical and experimental studies showed that the indium s orbitals in AgGa{sub 1-x}In{sub x}S{sub 2} tailored the band gap energy, thereby modified the photocatalytic activity of the AgGa{sub 1-x}In{sub x}S{sub 2}.

  16. Potential effects of gallium on cladding materials

    SciTech Connect

    Wilson, D.F.; Beahm, E.C.; Besmann, T.M.; DeVan, J.H.; DiStefano, J.R.; Gat, U.; Greene, S.R.; Rittenhouse, P.L.; Worley, B.A.

    1997-10-01

    This paper identifies and examines issues concerning the incorporation of gallium in weapons derived plutonium in light water reactor (LWR) MOX fuels. Particular attention is given to the more likely effects of the gallium on the behavior of the cladding material. The chemistry of weapons grade (WG) MOX, including possible consequences of gallium within plutonium agglomerates, was assessed. Based on the calculated oxidation potentials of MOX fuel, the effect that gallium may have on reactions involving fission products and possible impact on cladding performance were postulated. Gallium transport mechanisms are discussed. With an understanding of oxidation potentials and assumptions of mechanisms for gallium transport, possible effects of gallium on corrosion of cladding were evaluated. Potential and unresolved issues and suggested research and development (R and D) required to provide missing information are presented.

  17. Aluminium toxicity and iron homeostasis.

    PubMed

    Ward, R J; Zhang, Y; Crichton, R R

    2001-11-01

    In an animal model of aluminum overload, (aluminium gluconate), the increases in tissue aluminium content were paralleled by elevations of tissue iron in the kidney, liver heart and spleen as well as in various brain regions, frontal, temporal and parietal cortex and hippocampus. Despite such increases in iron content there were no significant changes in the activities of a wide range of cytoprotective enzymes apart from an increase in superoxide dismutase in the frontal cortex of the aluminium loaded rats. Such increases in tissue iron content may be attributed to the stabilisation of IRP-2 by aluminium thereby promoting transferrin receptor synthesis while blocking ferritin synthesis. Using the radioactive tracer (26)Al less than 1% of the injected dose was recovered in isolated ferritin, supporting previous studies which also found little evidence for aluminium storage within ferritin. The increases in brain iron may well be contributory to neurodegeneration, although the pathogenesis by which iron exerts such an effect is unclear.

  18. Gallium scan in intracerebral sarcoidosis

    SciTech Connect

    Makhija, M.C.; Anayiotos, C.P.

    1981-07-01

    Sarcoidosis involving the nervous system probably occurs in about 4% of patients. The usefulness of brain scintigraphy in these cases has been suggested. In this case of cerebral sarcoid granuloma, gallium imaging demonstrated the lesion before treatment and showed disappearance of the lesion after corticosteroid treatment, which correlated with the patient's clinical improvement.

  19. Gallium scintigraphy in acute panniculitis

    SciTech Connect

    Choy, D.; Murray, I.P.C.; Ford, J.C.

    1981-11-01

    Gallium scintigraphy was performed in a 27-yr-old female in search of a possible occult focus of infection; it showed an unusual diffuse superficial accumulation in the thighs and buttocks. Biopsy of an area of abnormal uptake showed lobular panniculitis which, in the clinical context, led to the diagnosis of Weber-Christian syndrome.

  20. Liquid gallium rotary electric contract

    NASA Technical Reports Server (NTRS)

    Przybyszewski, J. S.

    1969-01-01

    Due to its low vapor pressure, gallium, when substituted for mercury in a liquid slip ring system, transmits substantial amounts of electrical current to rotating components in an ultrahigh vacuum. It features low electrical loss, little or no wear, and long maintenance-free life.

  1. P-type gallium nitride

    DOEpatents

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

    1997-08-12

    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.

  2. P-type gallium nitride

    DOEpatents

    Rubin, Michael; Newman, Nathan; Fu, Tracy; Ross, Jennifer; Chan, James

    1997-01-01

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

  3. Comparative radiation resistance, temperature dependence and performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.

    1987-01-01

    Indium phosphide solar cells whose p-n junctions were processed by the open tube capped diffusion and by the closed tube uncapped diffusion of sulfur into Czochralski-grown p-type substrates are compared. Differences found in radiation resistance were attributed to the effects of increased base dopant concentration. Both sets of cells showed superior radiation resistance to that of gallium arsenide cells, in agreement with previous results. No correlation was, however, found between the open-circuit voltage and the temperature dependence of the maximum power.

  4. Gallium nitride electronics

    NASA Astrophysics Data System (ADS)

    Rajan, Siddharth; Jena, Debdeep

    2013-07-01

    In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it

  5. Aluminium, antiperspirants and breast cancer.

    PubMed

    Darbre, P D

    2005-09-01

    Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer. PMID:16045991

  6. Aluminium, antiperspirants and breast cancer.

    PubMed

    Darbre, P D

    2005-09-01

    Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer.

  7. The toxicity of aluminium in humans.

    PubMed

    Exley, C

    2016-06-01

    We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored. PMID:26922890

  8. The toxicity of aluminium in humans.

    PubMed

    Exley, C

    2016-06-01

    We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored.

  9. Epitaxial Deposition Of Germanium Doped With Gallium

    NASA Technical Reports Server (NTRS)

    Huffman, James E.

    1994-01-01

    Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

  10. Indium Foil Serves As Thermally Conductive Gasket

    NASA Technical Reports Server (NTRS)

    Eastman, G. Yale; Dussinger, Peter M.

    1993-01-01

    Indium foil found useful as gasket to increase thermal conductance between bodies clamped together. Deforms to fill imperfections on mating surfaces. Used where maximum temperature in joint less than melting temperature of indium. Because of low melting temperature of indium, most useful in cryogenic applications.

  11. Recovering gallium from residual bayer process liquor

    NASA Astrophysics Data System (ADS)

    Afonso de Magalhães, Maria Elizabeth; Tubino, Matthieu

    1991-06-01

    Gallium is normally obtained by direct electrolysis as a by-product from Bayer process residual liquor at an aluminum processing plant. However, to permit any net accumulation of the metal, the gallium concentration must be at least about 0.3 g/l in the liquor. This article describes a continuous process of extraction with organic solvents and rhodamine-B, followed by a re-extraction step into aqueous media. The final product is a solid containing up to 18 wt.% Ga in a solid mixture of hydroxides and oxides of gallium and aluminum. This final product can then be electrolyzed to recover the gallium more efficiently.

  12. Thermal oxidation of gallium arsenide

    SciTech Connect

    Monteiro, O.R.; Evans, J.W.

    1989-01-01

    Here we present some results of transmission electron microscopy and secondary ion mass spectroscopy of thermally oxidized gallium arsenide with different types of dopants. At temperatures below 400 /sup 0/C an amorphous oxide is formed. Oxidation at temperatures between 500 and 600 /sup 0/C initially produces an epitaxial film of ..gamma..-Ga/sub 2/O/sub 3/. As the reaction proceeds, this film becomes polycrystalline and then transforms to ..beta..-Ga/sub 2/O/sub 3/. This film contains small crystallites of As/sub 2/O/sub 5/ and As/sub 2/O/sub 3/ in the case of the chromium doped samples, whereas only the former was detected in the case of silicon and tellurium doped samples. Elemental arsenic was always found at the interface between the oxide and GaAs. Chromium doped gallium also exhibited a slower oxidation kinetics than the other materials.

  13. Synthesis, characterization and catalytic activity of indium substituted nanocrystalline Mobil Five (MFI) zeolite

    SciTech Connect

    Shah, Kishor Kr.; Nandi, Mithun; Talukdar, Anup K.

    2015-06-15

    Highlights: • In situ modification of the MFI zeolite by incorporation of indium. • The samples were characterized by XRD, FTIR, TGA, UV–vis (DRS), SAA, EDX and SEM. • The incorporation of indium was confirmed by XRD, FT-IR, UV–vis (DRS), EDX and TGA. • Hydroxylation of phenol reaction was studied on the synthesized catalysts. - Abstract: A series of indium doped Mobil Five (MFI) zeolite were synthesized hydrothermally with silicon to aluminium and indium molar ratio of 100 and with aluminium to indium molar ratios of 1:1, 2:1 and 3:1. The MFI zeolite phase was identified by XRD and FT-IR analysis. In XRD analysis the prominent peaks were observed at 2θ values of around 6.5° and 23° with a few additional shoulder peaks in case of all the indium incorporated samples suggesting formation of pure phase of the MFI zeolite. All the samples under the present investigation were found to exhibit high crystallinity (∼92%). The crystallite sizes of the samples were found to vary from about 49 to 55 nm. IR results confirmed the formation of MFI zeolite in all cases showing distinct absorbance bands near 1080, 790, 540, 450 and 990 cm{sup −1}. TG analysis of In-MFI zeolites showed mass losses in three different steps which are attributed to the loss due to adsorbed water molecules and the two types TPA{sup +} cations. Further, the UV–vis (DRS) studies reflected the position of the indium metal in the zeolite framework. Surface area analysis of the synthesized samples was carried out to characterize the synthesized samples The analysis showed that the specific surface area ranged from ∼357 to ∼361 m{sup 2} g{sup −1} and the pore volume of the synthesized samples ranged from 0.177 to 0.182 cm{sup 3} g{sup −1}. The scanning electron microscopy studies showed the structure of the samples to be rectangular and twinned rectangular shaped. The EDX analysis was carried out for confirmation of Si, Al and In in zeolite frame work. The catalytic activities of

  14. Facile synthesis of gallium oxide hydroxide by ultrasonic irradiation of molten gallium in water.

    PubMed

    Kumar, Vijay Bhooshan; Gedanken, Aharon; Porat, Ze'ev

    2015-09-01

    This work describes the single-step synthesis of GaO(OH) by ultrasonic irradiation of molten gallium in warm water. The ultrasonic energy causes dispersion of the liquid gallium into micrometric spheres, as-well-as decomposition of some of the water into H and OH radicals. The OH radicals and the dissolved oxygen react on the surface of the gallium spheres to form crystallites of GaO(OH). These crystallites prevent the re-coalescence of the gallium spheres, and as the reaction proceeds all the gallium is converted into crystalline GaO(OH).

  15. Magnetotransport properties of aluminum-indium-arsenic-antimony/gallium antimonide and optical properties of gallium-arsenic-antimony

    NASA Astrophysics Data System (ADS)

    Lukic-Zrnic, Reiko

    Multilayer structures of AlxIn1-xAs ySb1-y/GaSb (0.37 ≤ x ≤ 0.43, 0.50 ≤ y ≤ 0.52), grown by molecular beam epitaxy on GaSb (100) substrates were characterized using variable temperature Hall and Shubnikov-de Haas techniques. For nominally undoped structures both p and n-type conductivity was observed. The mobilities obtained were lower than those predicted by an interpolation method using the binary alloys; therefore, a detailed analysis of mobility versus temperature data was performed to extract the appropriate scattering mechanisms. For p-type samples, the dominant mechanism was ionized impurity scattering at low temperatures and polar optical phonon scattering at higher temperatures. For n-type samples, ionized impurity scattering was predominant at low temperatures, and electron-hole scattering dominated for both the intermediate and high temperature range. Analyses of the Shubnikov-de Haas data indicate the presence of 2-D carrier confinement consistent with energy subbands in GaAszSb1-z potential wells. Epilayers of GaAs1-xSbx (0.19 < x < 0.71), grown by MBE on semi-insulating GaAs with various substrate orientations, were studied by absorption measurements over the temperature range of 4--300 K. The various substrate orientations were chosen to induce different degrees of spontaneous atomic ordering. The temperature dependence of the energy gap (Eg) for each of these samples was modeled using three semi-empirical relationships. The resulting coefficients for each model describe not only the temperature dependence of Eg for each of the alloy compositions investigated, but also for all published results for this alloy system. The effect of ordering in these samples was manifested by a deviation of the value of Eg from the value of the random alloy. The presence of CuPt-B type atomic ordering was verified by transmission electron diffraction measurements, and the order parameter was estimated for all the samples investigated and found to be larger for the samples grown on the (111) A offcut orientations. This result strongly suggests that it is the A steps that contribute to the formation of the CuPt-B type ordering in the GaAs1-xSbx alloy system.

  16. Growth and characterization of room temperature ferromagnetic manganese:gallium nitride and manganese:gallium indium nitride for spintronic applications

    NASA Astrophysics Data System (ADS)

    Reed, Meredith Lynn

    Dilute magnetic semiconductors Mn:GaN and Mn:InGaN showing ferromagnetic behavior at room temperature and above were achieved. Light emitting diode devices doped with Mn via diffusion produced operational devices with ferromagnetic properties at room temperature. Mn:GaN films were grown by: Mn diffusion into metal organic chemical vapor deposition (MOCVD) grown GaN; ion implantation of Mn into MOCVD grown GaN substrates; and MOCVD growth of Mn:GaN using (Et,Cp)2Mn as a Mn precursor. Curie temperatures of these Mn:GaN films ranged from 228 to 520 K, as determined by temperature dependent super conducting quantum interference device (SQUID) and extraordinary Hall effect (EHE) measurements. Ferromagnetic properties were observed over a Mn concentration range of 0.09--3.5% depending on the growth technique used. The Mn:GaN coercivity ranged from 100--1500 Oe, where the saturation magnetization varied from 2 to 45 emu/cm3. The easy axes for these films were determined to be along the c direction (i.e. out of plane). The electrical properties of the Mn:GaN films indicated that the films were highly resistive or n-type. Temperature dependent SQUID and EHE measurements verified the absence of superparamagnetism in the films, confirming the absence of small phase separated particles within the films. XRD and TEM determined that no secondary phases were present in any of the films studied, confirming that the ferromagnetic properties result from a solid solution of Mn in the GaN lattice. Mn:InGaN films were grown by Mn diffusion into InGaN films and by MOCVD using (Et,Cp)2Mn as a Mn precursor. All Mn:InGaN films were grown on an undoped GaN template. We report on the room temperature ferromagnetic properties of Mn-doped InxGa1- xN with x < 0.15. The Curie temperatures for these Mn:InGaN films ranged from 300 to 700 K, which was confirmed by temperature dependent SQUID measurements. The ferromagnetic properties were observed in a Mn concentration range of 0.12--8% depending on how the films were grown. The coercivity of Mn:InGaN films were found to range from 100--800 Oe, where the saturation magnetization varied from 1 to 28 emu/cm3. The easy axis of magnetization depends on the stress state of the InxGa 1-xN film. The easy axis rotates from in-plane to out of plane by changing the film thickness, thus going from strained to fully relaxed films. For intermediate film thickness a transition region of partially relaxed film was identified with isotropic magnetic behavior. The electrical properties of the Mn:InGaN films indicated that the films were n-type or highly resistive. Temperature dependent SQUID measurements verified the absence of superparamagnetism in the films, confirming the absence of small phase separated particles within the films. XRD and TEM determined that no secondary phases were present in any of the films studied, confirming that the ferromagnetic properties result from a solid solution of Mn in the InGaN lattice.

  17. Ultrafast electronic dynamics in unipolar n-doped indium gallium arsenide/gallium arsenide self-assembled quantum dots

    NASA Astrophysics Data System (ADS)

    Wu, Zong-Kwei J.

    2006-12-01

    Photodetectors based on intraband infrared absorption in the quantum dots have demonstrated improved performance over its quantum well counterpart by lower dark current, relative temperature insensitivity, and its ability for normal incidence operation. Various scattering processes, including phonon emission/absorption and carrier-carrier scattering, are critical in understanding device operation on the fundamental level. In previous studies, our group has investigated carrier dynamics in both low- and high-density regime. Ultrafast electron-hole scattering and the predicted phonon bottleneck effect in intrinsic quantum dots have been observed. Further examination on electron dynamics in unipolar structures is presented in this thesis. We used n-doped quantum dot in mid-infrared photodetector device structure to study the electron dynamics in unipolar structure. Differential transmission spectroscopy with mid-infrared intraband pump and optical interband probe was implemented to measure the electron dynamics directly without creating extra electron-hole pair, Electron relaxation after excitation was measured under various density and temperature conditions. Rapid capture into quantum dot within ˜ 10 ps was observed due to Auger-type electron-electron scattering. Intradot relaxation from the quantum dot excited state to the ground state was also observed on the time scale of 100 ps. With highly doped electron density in the structure, the inter-sublevel relaxation is dominated by Auger-type electron-electron scattering and the phonon bottleneck effect is circumvented. Nanosecond-scale recovery in larger-sized quantum dots was observed, not intrinsic to electron dynamics but due to band-bending and built-in voltage drift. An ensemble Monte Carlo simulation was also established to model the dynamics in quantum dots and in goad agreement with the experimental results. We presented a comprehensive picture of electron dynamics in the unipolar quantum dot structure. Although the phonon bottleneck is circumvented with high doped electron density, relaxation processes in unipolar quantum dots have been measured with time scales longer than that of bipolar systems. The results explain the operation principles of the quantum dot infrared photodetector on a microscopic level and provide basic understanding for future applications and designs.

  18. Optical, structural, and transport properties of indium nitride, indium gallium nitride alloys grown by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Khan, Neelam

    InGaN based, blue and green light emitting diodes (LEDs) have been successfully produced over the past decade. But the progress of these LEDs is often limited by the fundamental problems of InGaN such as differences in lattice constants, thermal expansion coefficients and physical properties between InN and GaN. This difficulty could be addressed by studying pure InN and InxGa 1-xN alloys. In this context Ga-rich InxGa1-xN (x ≤ 0.4) epilayers were grown by metal organic chemical vapor deposition (MOCVD). X-ray diffraction (XRD) measurements showed InxGa1-xN films with x= 0.37 had single phase. Phase separation occurred for x ˜ 0.4. To understand the issue of phase separation in Ga-rich InxGa 1-xN, studies on growth of pure InN and In-rich InxGa 1-xN alloys were carried out. InN and In-rich InxGa1-xN (x ˜ 0.97-0.40) epilayers were grown on AlN/Al2O3 templates. A Hall mobility of 1400 cm2/Vs with a carrier concentration of 7x1018cm -3 was observed for InN epilayers grown on AlN templates. Photoluminescence (PL) emission spectra revealed a band to band emission peak at ˜0.75 eV for InN. This peak shifted to 1.15 eV when In content was varied from 1.0 to 0.63 in In-rich InxGa1-xN epilayers. After growth parameter optimization of In-rich InxGa1-xN alloys with (x = 0.97-0.40) were successfully grown without phase separation. Effects of Mg doping on the PL properties of InN epilayers grown on GaN/Al 2O3 templates were investigated. An emission line at ˜ 0.76 eV, which was absent in undoped InN epilayers and was about 60 meV below the band edge emission peak at ˜ 0.82 eV, was observed to be the dominant emission in Mg-doped InN epilayers. PL peak position and the temperature dependent emission intensity corroborated each other and suggested that Mg acceptor level in InN is about 60 meV above the valance band maximum. Strain effects on the emission properties of InGaN/GaN multiple quantum wells (MQWs) were studied using a single blue LED wafer possessing a continuous variation in compressive strain. EL emission peak position of LEDs varies linearly with the biaxial strain; a coefficient of 19 meV/GPa, characterizes the relationship between the band gap energy and biaxial stress of In 0.2Ga0.8N/GaN MQWs.

  19. Controlling Surface Chemistry of Gallium Liquid Metal Alloys to Enhance their Fluidic Properties

    NASA Astrophysics Data System (ADS)

    Ilyas, Nahid; Cumby, Brad; Cook, Alexander; Durstock, Michael; Tabor, Christopher; Materials; Manufacturing Directorate Team

    Gallium liquid metal alloys (GaLMAs) are one of the key components of emerging technologies in reconfigurable electronics, such as tunable radio frequency antennas and electronic switches. Reversible flow of GaLMA in microchannels of these types of devices is hindered by the instantaneous formation of its oxide skin in ambient environment. The oxide film sticks to most surfaces leaving unwanted metallic residues that can cause undesired electronic properties. In this report, residue-free reversible flow of a binary alloy of gallium (eutectic gallium indium) is demonstrated via two types of surface modifications where the oxide film is either protected by an organic thin film or chemically removed. An interface modification layer (alkyl phosphonic acids) was introduced into the microfluidic system to modify the liquid metal surface and protect its oxide layer. Alternatively, an ion exchange membrane was utilized as a 'sponge-like' channel material to store and slowly release small amounts of HCl to react with the surface oxide of the liquid metal. Characterization of these interfaces at molecular level by surface spectroscopy and microscopy provided with mechanistic details for the interfacial interactions between the liquid metal surface and the channel materials.

  20. Phase change cells and the verification of gallium as a thermal calibration reference in space

    NASA Astrophysics Data System (ADS)

    Latvikoski, Harri; Bingham, Gail E.; Topham, T. S.; Podolski, Igor

    2015-09-01

    The validation of models of global climate change and accurate measurement of the atmosphere and surface temperatures require that orbital sensors have low drift rates, and are monitored or regularly recalibrated by accepted standards. Phase change materials (PCM), such as those that make up the ITS-90 standard, are the basis for international commerce and have been suggested for monitoring and recalibration of orbital temperature sensors. Space Dynamics Laboratory (SDL) and its partners have been developing miniaturized phase change reference technologies that could be deployed on an orbital blackbody for nearly a decade. A significant part of this effort has been the exploration of the behavior of gallium (Ga) and its eutectics, gallium-tin (GaSn) and gallium-indium (GaIn) in conditions expected to be encountered in this application. In this paper, these behaviors are detailed and an example of a hardware design that could be used as an infrared blackbody calibration monitor is presented. To determine if and how microgravity will affect the behavior of Ga, the authors conducted an experiment on the International Space Station (ISS) and compared the observed phase change temperature with earth-based measurements. This paper also provides a brief description of the experiment hardware, microgravity considerations, and the pre-flight, flight and post-flight data analysis.

  1. Thin film gallium arsenide solar cell research. Third quarterly project report, September 1, 1980-November 30, 1980. [Antireflection coating

    SciTech Connect

    Chu, S. S.

    1980-12-01

    The major objective of this contract is to produce gallium arsenide solar cells of 10% conversion efficiency in films of less than 10 micrometers thick which have been deposited by chemical vapor deposition on graphite or tungsten coated graphite substrates. Major efforts during this quarter were directed to: (1) the optimization of the deposition of gallium arsenide films of 10 ..mu..m thickness or less on tungsten/graphic substrates, (2) the investigation of the effectiveness of various grain boundary passivation techniques, (3) the deposition of tantalum pentoxide by ion beam sputtering as an antireflection coating, (4) the deposition of gallium aluminium arsenide by the organometallic process, and (5) the fabrication and characterization of large area Schottky barrier type solar cells from gallium arsenide films of about 10 ..mu..m thickness. Various grain boundary passivation techniques, such as the anodic oxidation, thermal oxidation, and ruthenium treatment, have been investigated. The combination of thermal oxidation and ruthenium treatment has been used to fabricate Schottky barrier type solar cells. Large area MOS solar cells of 9 cm/sup 2/ area with AMl efficiency of 8.5% have been fabricated from ruthenium treated gallium arsenide films of 10 ..mu..m thickness. The construction of the apparatus for the deposition of gallium aluminum arsenide by the organometallic process has been completed. The deposition of good quality tantalum pentoxide film as an antireflection coating has been carried out by the ion beam sputtering technique. The short-circuit current density and AMl efficiency of the solar cells are increased by approximately 60%, with a slight increase in the open-circuit voltage. Details are presented. (WHK)

  2. Gallium Electromagnetic (GEM) Thrustor Concept and Design

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.

    2006-01-01

    We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

  3. Pulmonary Fibrosis in an Aluminium Worker

    PubMed Central

    Mitchell, John

    1959-01-01

    Aluminium dust has never been shown to be harmful to man in Great Britain. This paper reports a fatal case of progressive pulmonary fibrosis in a young man occupationally exposed to a heavy concentration of fine aluminium dust. Clinically, radiologically, and pathologically this case was indistinguishable from cases of aluminium fibrosis of the lung described by Shaver in Canada. Images PMID:13651554

  4. The study of aluminium anodes for high power density Al/air batteries with brine electrolytes

    NASA Astrophysics Data System (ADS)

    Nestoridi, Maria; Pletcher, Derek; Wood, Robert J. K.; Wang, Shuncai; Jones, Richard L.; Stokes, Keith R.; Wilcock, Ian

    Aluminium alloys containing small additions of both tin (∼0.1 wt%) and gallium (∼0.05 wt%) are shown to dissolve anodically at high rates in sodium chloride media at room temperatures; current densities >0.2 A cm -2 can be obtained at potentials close to the open circuit potential, ∼-1500 mV versus SCE. The tin exists in the alloys as a second phase, typically as ∼1 μm inclusions (precipitates) distributed throughout the aluminium structure, and anodic dissolution occurs to form pits around the tin inclusions. Although the distribution of the gallium in the alloy could not be established, it is also shown to be critical in the formation of these pits as well as maintaining their activity. The stability of the alloys to open circuit corrosion and the overpotential for high rate dissolution, both critical to battery performance, are shown to depend on factors in addition to elemental composition; both heat treatment and mechanical working influence the performance of the alloy. The correlation between alloy performance and their microstructure has been investigated.

  5. [Three cases of indium lung].

    PubMed

    Taguchi, Osamu; Chonan, Tatsuya

    2006-07-01

    The production of indium tin oxide (ITO) has been increasing during the past decade because of its use in liquid crystal and plasma display panels. Following the first report on lethal lung injury in a ITO worker in 2001, we began pulmonary check-ups for 115 workers in the plant in our capacity of industrial physicians of the plant. Hence, we report interstitial pulmonary disease in 3 workers who had engaged in wet-surface grinding of ITO for 8 to 12 years and had significant lung injuries. The serum indium level and serum concentration of KL-6 were significantly elevated in all 3 cases. One non-smoker case among them showed severe obstructive changes on spirometry and had an episode of repeated bilateral pneumothorax before and during the follow-up period. All 3 cases showed both interstitial and/or emphysematous changes on HRCT. It is suggested that inhaled indium compounds can cause a new and unique interstitial pulmonary disease.

  6. Clinical applications of Gallium-68.

    PubMed

    Banerjee, Sangeeta Ray; Pomper, Martin G

    2013-06-01

    Gallium-68 is a positron-emitting radioisotope that is produced from a (68)Ge/(68)Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. (68)Ga-DOTATOC, (8)Ga-DOTATATE, (68)Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with (68)Ga over the past few years around the world, including within the United States. An estimated ∼10,000 scans are being performed yearly in Europe at about 100 centers utilizing (68)Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied (68)Ga-labeled imaging agents used in nuclear medicine.

  7. Diffusion length variation in 0.5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Jain, Raj K.; Weinberg, Irving; Flood, Dennis J.

    1993-01-01

    Indium phosphide (InP) solar cells are more radiation resistant than gallium arsenide (GaAs) and silicon (Si) solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of light weight, mechanically strong, and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5- and 3-MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence was calculated by simulating the cell performance. The diffusion length damage coefficient, K(sub L), was also plotted as a function of proton fluence.

  8. Gallium arsenide deep-level optical emitter for fibre optics.

    PubMed

    Pan, Janet L; McManis, Joseph E; Osadchy, Thomas; Grober, Louise; Woodall, Jerry M; Kindlmann, Peter J

    2003-06-01

    Fibre-optic components fabricated on the same substrate as integrated circuits are important for future high-speed communications. One industry response has been the costly push to develop indium phosphide (InP) electronics. However, for fabrication simplicity, reliability and cost, gallium arsenide (GaAs) remains the established technology for integrated optoelectronics. Unfortunately, the GaAs bandgap wavelength (0.85 microm) is far too short for fibre optics at 1.3-1.5 microm. This has led to work on materials that have a large lattice mismatch on GaAs. Here we demonstrate the first light-emitting diode (LED) that emits at 1.5 microm fibre-optic wavelengths in GaAs using optical transitions from arsenic antisite (As(Ga)) deep levels. This is an enabling technology for fibre-optic components that are lattice-matched to GaAs integrated circuits. We present experimental results showing significant internal optical power (24 mW) and speed (in terahertz) from GaAs optical emitters using deep-level transitions. Finally, we present theory showing the ultimate limit to the efficiency-bandwidth product of semiconductor deep-level optical emitters.

  9. The surface tension of liquid gallium

    NASA Technical Reports Server (NTRS)

    Hardy, S. C.

    1985-01-01

    The surface tension of liquid gallium has been measured using the sessile drop technique in an Auger spectrometer. The experimental method is described. The surface tension in mJ/sq m is found to decrease linearly with increasing temperature and may be represented as 708-0.66(T-29.8), where T is the temperature in centigrade. This result is of interest because gallium has been suggested as a model fluid for Marangoni flow experiments. In addition, the surface tension is of technological significance in the processing of compound semiconductors involving gallium.

  10. The prophylactic reduction of aluminium intake.

    PubMed

    Lione, A

    1983-02-01

    The use of modern analytical methods has demonstrated that aluminium salts can be absorbed from the gut and concentrated in various human tissues, including bone, the parathyroids and brain. The neurotoxicity of aluminium has been extensively characterized in rabbits and cats, and high concentrations of aluminium have been detected in the brain tissue of patients with Alzheimer's disease. Various reports have suggested that high aluminium intakes may be harmful to some patients with bone disease or renal impairment. Fatal aluminium-induced neuropathies have been reported in patients on renal dialysis. Since there are no demonstrable consequences of aluminium deprivation, the prophylactic reduction of aluminium intake by many patients would appear prudent. In this report, the major sources of aluminium in foods and non-prescription drugs are summarized and alternative products are described. The most common foods that contain substantial amounts of aluminium-containing additives include some processed cheeses, baking powders, cake mixes, frozen doughs, pancake mixes, self-raising flours and pickled vegetables. The aluminium-containing non-prescription drugs include some antacids, buffered aspirins, antidiarrhoeal products, douches and haemorrhoidal medications. The advisability of recommending a low aluminium diet for geriatric patients is discussed in detail. PMID:6337934

  11. Occupational asthma caused by aluminium welding.

    PubMed

    Vandenplas, O; Delwiche, J P; Vanbilsen, M L; Joly, J; Roosels, D

    1998-05-01

    Work-related asthma has been documented in workers employed in the primary aluminium industry and in the production of aluminium salts. The role of aluminium in the development of occupational asthma has, however, never been convincingly substantiated. We investigated a subject who experienced asthmatic reactions related to manual metal arc welding on aluminium. Challenge exposure to aluminium welding with flux-coated electrodes, as well as with electrodes without flux, elicited marked asthmatic reactions. Manual metal arc welding on mild steel did not cause significant bronchial response. The results of inhalation challenges combined with exposure assessments provided evidence that aluminium can cause asthmatic reactions in the absence of fluorides. Awareness of this possibility may be relevant to the investigation of asthma in workers exposed to aluminium. PMID:9648975

  12. Aluminium toxicity in chronic renal insufficiency

    SciTech Connect

    Savory, J.; Bertholf, R.L.; Wills, M.R.

    1985-08-01

    Aluminium is a ubiquitous element in the environment and has been demonstrated to be toxic, especially in individuals with impaired renal function. Not much is known about the biochemistry of aluminium and the mechanisms of its toxic effects. Most of the interest in aluminium has been in the clinical setting of the hemodialysis unit. Here aluminium toxicity occurs due to contamination of dialysis solutions, and treatment of the patients with aluminium-containing phosphate binding gels. Aluminium has been shown to be the major contributor to the dialysis encephalopathy syndrome and an osteomalacic component of dialysis osteodystrophy. Other clinical disturbances associated with aluminium toxicity are a microcytic anemia and metastatic extraskeletal calcification. Aluminium overload can be treated effectively by chelation therapy with desferrioxamine and hemodialysis. Aluminium is readily transferred from the dialysate to the patient's -bloodstream during hemodialysis. Once transferred, the aluminium is tightly bound to non-dialysable plasma constituents. Very low concentrations of dialysate aluminium in the range of 10-15 micrograms/l are recommended to guard against toxic effects. Very few studies have been directed towards the separation of the various plasma species which bind eluminium. Gel filtration chromatography has been used to identify five major fractions, one of which is of low molecular weight and the others appear to be protein-aluminium complexes. Recommendations on aluminium monitoring have been published and provide safe and toxic concentrations. Also, the frequency of monitoring has been addressed. Major problems exist with the analytical methods for measuring aluminium which result from inaccurate techniques and contamination difficulties. 136 references.

  13. Gallium and its competing roles with iron in biological systems.

    PubMed

    Chitambar, Christopher R

    2016-08-01

    Gallium, a group IIIa metal, shares chemical properties with iron. Studies have shown that gallium-based compounds have potential therapeutic activity against certain cancers and infectious microorganisms. By functioning as an iron mimetic, gallium perturbs iron-dependent proliferation processes in tumor cells. Gallium's action on iron homeostasis leads to disruption of ribonucleotide reductase, mitochondrial function, and the regulation of transferrin receptor and ferritin. In addition, gallium nitrate stimulates an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Gallium's anti-infective activity against bacteria and fungi results from disruption of microbial iron utilization through mechanisms which include gallium binding to siderophores and downregulation of bacterial iron uptake. Gallium compounds lack cross-resistance to conventional chemotherapeutic drugs and antibiotics thus making them attractive agents for drug development. This review will focus on the mechanisms of action of gallium with emphasis on its interaction with iron and iron proteins. PMID:27150508

  14. Gallium and its competing roles with iron in biological systems.

    PubMed

    Chitambar, Christopher R

    2016-08-01

    Gallium, a group IIIa metal, shares chemical properties with iron. Studies have shown that gallium-based compounds have potential therapeutic activity against certain cancers and infectious microorganisms. By functioning as an iron mimetic, gallium perturbs iron-dependent proliferation processes in tumor cells. Gallium's action on iron homeostasis leads to disruption of ribonucleotide reductase, mitochondrial function, and the regulation of transferrin receptor and ferritin. In addition, gallium nitrate stimulates an increase in mitochondrial reactive oxygen species in cells which triggers downstream upregulation of metallothionein and hemoxygenase-1. Gallium's anti-infective activity against bacteria and fungi results from disruption of microbial iron utilization through mechanisms which include gallium binding to siderophores and downregulation of bacterial iron uptake. Gallium compounds lack cross-resistance to conventional chemotherapeutic drugs and antibiotics thus making them attractive agents for drug development. This review will focus on the mechanisms of action of gallium with emphasis on its interaction with iron and iron proteins.

  15. Gallium-67 activity in bronchoalveolar lavage fluid in sarcoidosis

    SciTech Connect

    Trauth, H.A.; Heimes, K.; Schubotz, R.; von Wichert, P.

    1986-01-01

    Roentgenograms and gallium-67 scans and gallium-67 counts of BAL fluid samples, together with differential cell counts, have proved to be useful in assessing activity and lung involvement in sarcoidosis. In active pulmonary sarcoidosis gallium-67 scans are usually positive. Quantitation of gallium-67 uptake in lung scans, however, may be difficult. Because gallium-67 uptake and cell counts in BAL fluid may be correlated, we set out to investigate gallium-67 activity in BAL fluid recovered from patient of different groups. Sixteen patients with recently diagnosed and untreated sarcoidosis, nine patients with healthy lungs, and five patients with CFA were studied. Gallium-67 uptake of the lung, gallium-67 activity in the lavage fluid, SACE and LACE levels, and alpha 1-AT activity were measured. Significantly more gallium-67 activity was found in BAL fluid from sarcoidosis patients than in that from CFA patients (alpha = .001) or patients with healthy lungs (alpha = .001). Gallium-67 activity in BAL fluid could be well correlated with the number of lymphocytes in BAL fluid, but poorly with the number of macrophages. Subjects with increased levels of SACE or serum alpha 1-AT showed higher lavage gallium-67 activity than did normals, but no correlation could be established. High gallium-67 activity in lavage fluid may be correlated with acute sarcoidosis or physiological deterioration; low activity denotes change for the better. The results show that gallium-67 counts in BAL fluid reflects the intensity of gallium-67 uptake and thus of activity of pulmonary sarcoidosis.

  16. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching

    SciTech Connect

    Swain, Basudev Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo Lee, Chan Gi; Hong, Hyun Seon

    2015-04-15

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na{sub 2}CO{sub 3}, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na{sub 2}CO{sub 3}, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4 M HCl, 100 °C and pulp density of 20 g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. - Highlights: • Simplest process for treatment of GaN an LED industry waste developed. • The process developed recovers gallium from waste LED waste dust. • Thermal analysis and phase properties of GaN to Ga{sub 2}O{sub 3} and GaN to NaGaO{sub 2} revealed. • Solid-state chemistry involved in this process reported. • Quantitative leaching of the GaN was achieved.

  17. Recovery of gallium from aluminum industry residues

    SciTech Connect

    Carvalho, M.S.; Neto, K.C.M.; Nobrega, A.W.; Medeiros, J.A.

    2000-01-01

    A procedure is proposed to recover gallium from flue dust aluminum residues produced in plants by using solid-phase extraction with a commercial polyether-type polyurethane foam (PUF). Gallium can be separated from high concentrations of aluminum, iron, nickel, titanium, vanadium, copper, zinc, sulfate, fluoride, and chloride by extraction with PUF from 3 M sulfuric acid and 3 M sodium chloride concentration medium with at least a 92% efficiency. Gallium backextraction was fast and quantitative with ethanol solution. In all recovery steps commercial-grade reagents could be used, including tap water. The recovered gallium was precipitated with sodium hydroxide solution, purified by dissolution and precipitation, calcinated, and the final oxide was 98.6% pure.

  18. Radiochemical separation of gallium by amalgam exchange

    USGS Publications Warehouse

    Ruch, R.R.

    1969-01-01

    An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

  19. Comparative performance of diffused junction indium phosphide solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Ghandhi, S. K.; Borrego, J. M.; Parat, K. K.

    1987-01-01

    A comparison is made between indium phosphide solar cells whose p-n junctions were processed by open tube capped diffusion, and closed tube uncapped diffusion, of sulfur into Czochralski grown p-type substrates. Air mass zero, total area, efficiencies ranged from 10 to 14.2 percent, the latter value attributed to cells processed by capped diffusion. The radiation resistance of these latter cells was slightly better, under 1 MeV electron irradiation. However, rather than being process dependent, the difference in radiation resistance could be attributed to the effects of increased base dopant concentration. In agreement with previous results, both cells exhibited radiation resistance superior to that of gallium arsenide. The lowest temperature dependency of maximum power was exhibited by the cells prepared by open tube capped diffusion. Contrary to previous results, no correlation was found between open circuit voltage and the temperature dependency of Pmax. It was concluded that additional process optimization was necessary before concluding that one process was better than another.

  20. Development of gallium arsenide solar cells

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The potential of ion implantation as a means of developing gallium arsenide solar cells with high efficiency performance was investigated. Computer calculations on gallium arsenide cell characteristics are presented to show the effects of surface recombination, junction space-charge recombination, and built-in fields produced by nonuniform doping of the surface region. The fabrication technology is summarized. Electrical and optical measurements on samples of solar cells are included.

  1. Generator for gallium-68 and compositions obtained therefrom

    DOEpatents

    Neirinckx, Rudi D.; Davis, Michael A.

    1981-01-01

    A generator for obtaining radioactive gallium-68 from germanium-68 bound in a resin containing unsubstituted phenolic hydroxyl groups. The germanium-68 is loaded into the resin from an aqueous solution of the germanium-68. A physiologically acceptable solution of gallium-68 having an activity of 0.1 to 50 millicuries per milliliter of gallium-68 solution is obtained. The solution is obtained from the bound germanium-68 which forms gallium-68 in situ by eluting the column with a hydrochloric acid solution to form an acidic solution of gallium-68. The acidic solution of gallium-68 can be neutralized.

  2. Bumblebee Pupae Contain High Levels of Aluminium

    PubMed Central

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer’s disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline. PMID:26042788

  3. Bumblebee pupae contain high levels of aluminium.

    PubMed

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer's disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline.

  4. Bumblebee pupae contain high levels of aluminium.

    PubMed

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer's disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline. PMID:26042788

  5. Gallium poisoning: a rare case report.

    PubMed

    Ivanoff, Chris S; Ivanoff, Athena E; Hottel, Timothy L

    2012-02-01

    The authors present a case of a college student who suffered acute gallium poisoning as a result of accidental exposure to gallium halide complexes. This is extremely rare and has never been reported in the literature. Acute symptoms after the incident, which initially presented as dermatitis and appeared relatively not life-threatening, rapidly progressed to dangerous episodes of tachycardia, tremors, dyspnea, vertigo, and unexpected black-outs. Had there been effective emergency medical care protocols, diagnostic testing, treatment and antidotes, the latent manifestations of irreversible cardiomyopathy may have been prevented. Given how quickly exposure led to morbidity, this article aims to raise an awareness of the toxic potential of gallium. This has particular relevance for workers involved in the production of semiconductors where there is a potential for accidental exposure to gallium by-products during device processing. It may also have implications for dentists who use gallium alloys to replace mercury containing amalgam. In the absence of threshold limit values and exposure limits for humans, as well as emergency medical guidelines for treatment of poisoning, the case calls on the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration to establish guidelines and medical management protocols specific for gallium.

  6. Process for Patterning Indium for Bump Bonding

    NASA Technical Reports Server (NTRS)

    Denis, Kevin

    2012-01-01

    An innovation was created for the Cosmology Large Angular Scale Surveyor for integration of low-temperature detector chips with a silicon backshort and a silicon photonic choke through flipchip bonding. Indium bumps are typically patterned using liftoff processes, which require thick resist. In some applications, it is necessary to locate the bumps close to high-aspect-ratio structures such as wafer through-holes. In those cases, liftoff processes are challenging, and require complicated and time-consuming spray coating technology if the high-aspect-ratio structures are delineated prior to the indium bump process. Alternatively, processing the indium bumps first is limited by compatibility of the indium with subsequent processing. The present invention allows for locating bumps arbitrarily close to multiple-level high-aspect-ratio structures, and for indium bumps to be formed without liftoff resist. The process uses the poor step coverage of indium deposited on a silicon wafer that has been previously etched to delineate the location of the indium bumps. The silicon pattern can be processed through standard lithography prior to adding the high-aspect-ratio structures. Typically, high-aspectratio structures require a thick resist layer so this layer can easily cover the silicon topography. For multiple levels of topography, the silicon can be easily conformally coated through standard processes. A blanket layer of indium is then deposited onto the full wafer; bump bonding only occurs at the high points of the topography.

  7. Aluminium in Allergies and Allergen immunotherapy.

    PubMed

    Jensen-Jarolim, Erika

    2015-01-01

    Aluminium is a hot topic in the current debate. Exposure occurs due to environmental, dietary and intentional exposure to aluminium, such as in vaccines where it was introduced in 1926. In spite of the fact that it is a typical Th2 adjuvant, aluminium redirects the immune response in systemic allergen immunotherapy (SIT) upon prolonged immunization. SIT in the US, and SLIT in general, are at present non-adjuvanted therapies, but in Europe aluminium is used as adjuvant in most SIT preparations. It enhances the safety of SIT by local deposition of the allergen. Undesired properties of aluminium adjuvants comprise acute and chronic inflammation at the injection site, its Th2 immune stimulatory capacity, its accumulation besides biodistribution in the body. The adjuvant and safety profile of aluminium adjuvants in allergy vaccines are discussed, as well as the need for putting modern delivery systems and adjuvants on the fast track.

  8. Temperature and baric dependence of nuclear quadruple resonance spectra in indium and gallium monoselenides

    NASA Astrophysics Data System (ADS)

    Khandozhko, Victor; Raranskii, Nikolai; Balazjuk, Vitaly; Samila, Andriy; Kovalyuk, Zahar

    2013-12-01

    Pulsed radiospectroscopy method has been used to study nuclear quadruple resonance (NQR) spectra of 69Ga and 115In isotopes in the layered semiconductors GaSe and InSe. It has been found that in GaSe and InSe there is a considerable temperature dependence of NQR frequency which in the temperature range of 250 to 390 K is practically linear with conversion slope 1.54 kHz/degree for 69Ga and 2.35 kHz/degree for 115In. In the same crystals the effect of uniaxial pressure on NQR spectra applied along the optical axis с up to the values of 500 kg/сm2 has been studied. A strong attenuation of NQR spectra intensity with increase in pressure on layered crystal package has been established. The unvaried multiplicity of resonance spectra indicates the absence of structural transformations in these layered crystals over the investigated range of temperatures and pressures.

  9. Electric Field-aided Selective Activation for Indium-Gallium-Zinc-Oxide Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Lee, Heesoo; Chang, Ki Soo; Tak, Young Jun; Jung, Tae Soo; Park, Jeong Woo; Kim, Won-Gi; Chung, Jusung; Jeong, Chan Bae; Kim, Hyun Jae

    2016-10-01

    A new technique is proposed for the activation of low temperature amorphous InGaZnO thin film transistor (a-IGZO TFT) backplanes through application of a bias voltage and annealing at 130 °C simultaneously. In this ‘electrical activation’, the effects of annealing under bias are selectively focused in the channel region. Therefore, electrical activation can be an effective method for lower backplane processing temperatures from 280 °C to 130 °C. Devices fabricated with this method exhibit equivalent electrical properties to those of conventionally-fabricated samples. These results are analyzed electrically and thermodynamically using infrared microthermography. Various bias voltages are applied to the gate, source, and drain electrodes while samples are annealed at 130 °C for 1 hour. Without conventional high temperature annealing or electrical activation, current-voltage curves do not show transfer characteristics. However, electrically activated a-IGZO TFTs show superior electrical characteristics, comparable to the reference TFTs annealed at 280 °C for 1 hour. This effect is a result of the lower activation energy, and efficient transfer of electrical and thermal energy to a-IGZO TFTs. With this approach, superior low-temperature a-IGZO TFTs are fabricated successfully.

  10. Radiation Effects in ALUMINUM(X)GALLIUM(1-X)ARSENIDE and Indium-Phosphorus

    NASA Astrophysics Data System (ADS)

    Cross, T. A.

    Available from UMI in association with The British Library. Radiation effects in Al_{ rm x}Ga_{rm 1-x}As and InP produced by hydrogen ion bombardment have been studied using mainly electrical resistivity measurements and thermal annealing techniques. Multiple energy ion bombardments at 400 keV to 100 keV were used in most experiments at beam power densities of below 100 mW cm^{-2}. Two terminal, through layer, resistivity measurements were made on Al_{rm x}Ga _{rm 1-x}As:Se with Al mole fraction, x, from 0 (GaAs) to 0.82. In all cases, a maximum resistivity of 1E8 to 1E10 ohm cm was achieved with proton or deuteron bombardment. As x is increased from 0 the resistivity maximum rises gradually from 1E8 to 1E10 ohm cm at x = 0.45 and then gently falls. This behaviour has been explained by considering a single deep level with an activation energy which varies with x in a similar manner to that of the shallow donor levels in Al_{rm x}Ga _{rm 1-x}As. Using an interdigital contact geometry, the first in-situ measurements of the change in Al_ {rm x}Ga_{rm 1-x}As resistivity with ion dose have been made. This has enabled repeated irradiation-measurement cycles, resulting in a rapid determination of the resistivity behaviour and a more accurate measurement of the optimum ion dose for maximum resistivity. The observed anomalously efficient carrier removal of deuterons in GaAs:Si has not been observed in any GaAs:Se or Al_{rm x}Ga _{rm 1-x}As:Se. Proton bombardment is less efficient in GaAs:Si than in GaAs:Se, perhaps due to a parasitic interaction of the protons with the silicon donor species. The thermal stability of the isolation in Al _{rm x}Ga_ {rm 1-x}As:Se, over the whole composition range, appears to be suitable for device applications if post-implant process steps are kept below 400^ circC. Whilst the isolation in InP was observed to be stable to up to 300^circC, some indications of room temperature annealing were noted. The electrical properties of proton and deuteron bombarded material appear to be closely similar. However, preliminary Rutherford Back Scattering (RBS) and optical absorption measurements on Al_{rm x}Ga_{rm 1-x} As samples have indicated differences. RBS has shown the level of disorder introduced by deuteron bombardments to be slightly higher than expected compared with proton bombardments. Optical absorption has shown the optical activity of the deuteron induced damage to be more intense. (Abstract shortened by UMI.).

  11. Efficiency droop in indium gallium nitride light emitters: An introduction to photon quenching processes

    NASA Astrophysics Data System (ADS)

    Sarkissian, Raymond

    This thesis contains work from two separate projects, a study of the efficiency of light emitting diodes, and a tapered-fiber approach to photonic crystal integrated photonics. The first part of this thesis describes an experimental investigation of the quantum efficiency of InGaN-based light emitters. Blue and Green LEDs that utilize InGaN quantum wells for their active medium suffer from a reduction in efficiency with increasing bias. This phenomenon is called efficiency droop. In this thesis experimental evidence for significant quenching of photon population in InGaN is presented and its relevance to the efficiency droop problem in InGaN-based light emitting structures is discussed. An equilibrium rate equation model is set up to demonstrate that radiative efficiency for this loss mechanism not only has a similar dependence on carrier density as Auger recombination process, but it also possesses the right order of magnitude making it difficult to distinguish between the two and possibly leading to errors in interpretation. The impact of photon quenching processes on device performance is emphasized by demonstrating loss of efficiency for spectral regions where there is experimental evidence for photon quenching. We have observed this phenomenon for both c-plane and m-plane light emitting structures. Both structures exhibit droop-like behavior for spectral regions where there is evidence for photon quenching. We have also observed and characterized the dynamical Stark effect for an m-plane light emitter considered in this manuscript. Our results revealed localization centers with a corresponding band-edge energy of 388nm and an excitonic binding energy of 17.81mev. Furthermore, fabrication of a photonic crystal waveguide fiber taper coupler is demonstrated with a peak coupling efficiency of 97 %. All four ports of the device are accessible providing an opportunity for investigation of simultaneous interaction of different light sources inside the photonic crystal cavity. A numerical model is set forth to analyze such devices with an excellent agreement with the experimental data. One important result of that theory is the ability to experimentally extract the phase contribution of optical resonators that employ periodic structures such as photonic crystal cavities. This device has also been used to demonstrate all-optical nonlinear shift and bleaching of cavity resonances via non-degenerate two photon absorption, non-degenerate Kerr mechanism, free carrier absorption, and free carrier plasma effects. As the response time of two photon processes are very fast, about 10 fs, this device can be used in ultrafast low energy all optical switching applications.

  12. Size-effects in indium gallium arsenide nanowire field-effect transistors

    NASA Astrophysics Data System (ADS)

    Zota, Cezar B.; Lind, E.

    2016-08-01

    We fabricate and analyze InGaAs nanowire MOSFETs with channel widths down to 18 nm. Low-temperature measurements reveal quantized conductance due to subband splitting, a characteristic of 1D systems. We relate these features to device performance at room-temperature. In particular, the threshold voltage versus nanowire width is explained by direct observation of quantization of the first sub-band, i.e., band gap widening. An analytical effective mass quantum well model is able to describe the observed band structure. The results reveal a compromise between reliability, i.e., VT variability, and on-current, through the mean free path, in the choice of the channel material.

  13. Photoluminescence Investigation of Electronic Processes in GALLIUM(0.52) INDIUM(0.48) Phosphorus

    NASA Astrophysics Data System (ADS)

    Delong, Matthew Charles

    The optical properties of Ga_{0.52 }In_{0.48}P have been investigated by the use of a number of variations of photoluminescence (PL). Ga_{0.52 }In_{0.48}P is interesting not only because of its commercial applicability in highly efficient solar cells and light emitting devices but also from a fundamental scientific standpoint as a result of its strong tendency to form an ordered structure. The extent of ordering within the small volumes (domains) where it occurs as well as the sizes of these volumes and fraction of a sample which is ordered or not ordered as well as estimates of the volume fractions ordered in the four nominally equivalent {111 } directions can be semi-quantitatively estimated by transmission electron diffraction (TED). In addition to the fact that Ga_{0.52}In _{0.48}P displays a strong tendency to order under some conditions of growth, it is also found that the band gap may vary by as much as 90 meV at constant composition, depending on conditions of growth. The band gap variation is believed to be related to ordering, although the details of the correlation have yet to be established. In this work the optical properties of a large number of samples of Ga_{0.52} In_{0.48}P have been studied as functions of growth conditions with the objective of determining how the growth conditions determine details of the microstructure by observing the influence of those microstructural changes on the optical properties. A number of variations of the PL technique were used, including excitation intensity, analysis temperature, time/frequency and microwave modulation dependence of the PL. It was determined in the course of this work that some partially ordered samples of Ga_{0.52 }In_{0.48}P, whose band gap is reduced considerably from that which is characteristic of disordered material, have a PL emission peak whose energy depends strongly on the intensity of the light with which the PL is excited. The lifetime of this emission was also found to be dependent on excitation intensity. Such behavior is typically characteristic of materials containing internal electric fields, suggesting the presence of such fields in ordered Ga_ {0.52}In_{0.48} P.

  14. Fourier spectrum based extraction of an equivalent trap state density in indium gallium zinc oxide transistors

    SciTech Connect

    Thakur, Bikash; Sambandan, Sanjiv; Lee, Sungsik; Nathan, Arokia; Ahnood, Arman; Jeon, Sanghun

    2014-05-19

    Segregating the dynamics of gate bias induced threshold voltage shift, and in particular, charge trapping in thin film transistors (TFTs) based on time constants provides insight into the different mechanisms underlying TFTs instability. In this Letter we develop a representation of the time constants and model the magnitude of charge trapped in the form of an equivalent density of created trap states. This representation is extracted from the Fourier spectrum of the dynamics of charge trapping. Using amorphous In-Ga-Zn-O TFTs as an example, the charge trapping was modeled within an energy range of ΔE{sub t}≈ 0.3 eV and with a density of state distribution as D{sub t}(E{sub t−j})=D{sub t0}exp(−ΔE{sub t}/kT)with D{sub t0} = 5.02 × 10{sup 11} cm{sup −2} eV{sup −1}. Such a model is useful for developing simulation tools for circuit design.

  15. Amorphous indium gallium zinc oxide thin film grown by pulse laser deposition technique

    NASA Astrophysics Data System (ADS)

    Mistry, Bhaumik V.; Joshi, U. S.

    2016-05-01

    Highly electrically conducting and transparent in visible light IGZO thin film were grown on glass substrate at substrate temperature of 400 C by a pulse laser deposition techniques. Structural, surface, electrical, and optical properties of IGZO thin films were investigated at room temperature. Smooth surface morphology and amorphous nature of the film has been confirmed from the AFM and GIXRD analysis. A resistivity down to 7.7×10-3 V cm was reproducibly obtained while maintaining optical transmission exceeding 70% at wavelengths from 340 to 780 nm. The carrier densities of the film was obtain to the value 1.9×1018 cm3, while the Hall mobility of the IGZO thin film was 16 cm2 V-1S-1.

  16. Impact of secondary barriers on copper-indium-gallium-selenide solar-cell operation

    NASA Astrophysics Data System (ADS)

    Pudov, Alexei O.

    Thin-film solar cells based on CuInSe2 (CIS) absorber with a band gap of Eg = 1.0 eV and also based on CuIn1-x GaxSe2 (CIGS) alloy absorbers with a band-gap range of Eg = 1.0--1.67 eV are investigated in this work. Intermediate "buffer" semiconductor layers in p-n junctions of CIGS solar cells often improve photodiode properties of the devices. The primary goal of the thesis is to study secondary barriers in the conduction band at the buffer/absorber interface, which may limit current transport and thus reduce the efficiency of the solar cells. The secondary goal is to explore alternative wide-bandgap buffers in CIGS cell structures. CIGS cells with standard CdS buffer layers, and alternative ZnS(O,OH) and InS(O,OH) buffer layers were studied. CdS/CuIn1-xGaxSe2 solar cells with variable Ga content have a range of conduction-band offsets (DeltaEc) in the junction from moderately positive (spike offsets) in CdS/CuInSe2 to moderately negative (cliff offsets) in CdS/CuGaSe 2. Moderate conduction-band spikes in CdS/CIS and low-Ga CdS/CIGS are expected to cause distortions in diode current-voltage (J-V) curves of such solar cells under "red" illumination (hnu < Eg(buffer)); no J-V distortions are expected for high-Ga CdS/CIGS with cliff offsets. These predictions were confirmed in experiments: the distortions were absent for cells with Eg above 1.2--1.3 eV, at which CdS/CIGS DeltaE c is near zero. Experiments and numerical simulations showed that one approach to reduce secondary barriers and J-V distortions in low-Ga high-spike cells is to thin the buffer layer(s). Blue photons (hnu above Eg(buffer)) in the solar spectrum induce photoconductivity in the otherwise compensated buffers, which also results in lowering of the secondary barriers. It was shown that CIGS cells with CdS, InS(O,OH), and ZnS(O,OH) buffers have a similar response to "blue" photons: J-V distortion, if present under red light, is reduced or entirely disappears with blue-light exposure within minutes. The distortion re-appearance without blue light is the order of a thousand times slower. Using wider-gap buffers, such as InS(O,OH) and ZnS(O,OH), was shown to produce higher photocurrents in solar cells. This photocurrent improvement is a central direction in the effort of further increasing efficiencies of thin-film solar cells.

  17. Single-fluxon controlled resistance switching in centimeter-long superconducting gallium-indium eutectic nanowires.

    PubMed

    Zhao, Weiwei; Bischof, Jesse L; Hutasoit, Jimmy; Liu, Xin; Fitzgibbons, Thomas C; Hayes, John R; Sazio, Pier J A; Liu, Chaoxing; Jain, Jainendra K; Badding, John V; Chan, M H W

    2015-01-14

    The ability to manipulate a single quantum object, such as a single electron or a single spin, to induce a change in a macroscopic observable lies at the heart of nanodevices of the future. We report an experiment wherein a single superconducting flux quantum, or a fluxon, can be exploited to switch the resistance of a nanowire between two discrete values. The experimental geometry consists of centimeter-long nanowires of superconducting Ga-In eutectic, with spontaneously formed Ga nanodroplets along the length of the nanowire. The nonzero resistance occurs when a Ga nanodroplet traps one or more superconducting fluxons, thereby driving a Josephson weak-link created by a second nearby Ga nanodroplet normal. The fluxons can be inserted or flipped by careful manipulation of the magnetic field or temperature to produce one of many metastable states of the system. PMID:25426926

  18. Thermochemistry and phase diagram studies in the copper(indium,gallium)selenium system

    NASA Astrophysics Data System (ADS)

    Ider, Muhsin

    Polycrystalline Cu(In,Ga)Se2 and related semiconductors show great potential as alternative materials in production of high efficiency solar cells. This dissertation reports the experimental determination of Gibbs energy changes and phase diagram calculations for selected sections of the Cu-Ga-In-Se system. The Gibbs energy changes were measured with solid-state electrochemical cells and this data along with selected literature data were assessed and model parameters suggested. The homogeneity range of beta-Cu2-xSe was measured by coulometric titration and the thermodynamic properties for defect species estimated. The composition difference between the Se-rich and the Cu-rich boundaries was measured at 900K. A defect model was developed based on vacancy formation on the Cu sublattice. The gas phase equilibrium data for Cu-Se system and the results of a recent assessment of selenium unary system were used to predict defect concentrations. A thermodynamic description of the Cu2Se-In2Se 3 was obtained by optimization of the available phase equilibrium and thermodynamic information along with the direct results of EMF experiments. The Gibbs energy of formation of alpha-CuInSe2 was directly measured by a solid oxide galvanic cell experiment. The transformation enthalpy and Gibbs energy data for CuIn3Se5 and CuIn5Se 8 were estimated. The Redlich-Kister model with a 3-coefficient expression was employed to define the Gibbs energy of the liquid phase. The intermediate beta-CuIn 3Se5 and gamma-CuIn5Se8 phases were modeled with a 2-coefficient expansion of the Redlich-Kister model. The alpha and delta modifications of CuInSe2 phases were modeled with a specific sublattice model. A reasonable agreement between the model calculated values and the thermodynamic phase equilibrium data was achieved. The thermochemistry and phase diagram of GaSe system was critically studied. The activity of Ga was measured along the liquidus between 800--1000K. Selected invariant phase transition temperatures were measured and transition enthalpies were calculated from the EMF measurements. A self-consistent thermodynamic data was obtained. The associated and sublattice models were used to represent the Gibbs energy of the liquid and alpha-Ga2Se3 phases, respectively. The Gibbs energy of formation of CuGaSe2 was measured by an EMT experiment. The phase diagram of Cu-Ga system was calculated and the liquid phase Ga activity measurements was measured for 2 Ga rich compositions.

  19. Radiation and temperature effects in gallium arsenide, indium phosphide, and silicon solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Statler, R. L.

    1987-01-01

    The effects of radiation on performance are determined for both n+p and p+n GaAs and InP cells and for silicon n+p cells. It is found that the radiation resistance of InP is greater than that of both GaAs and Si under 1-MeV electron irradiation. For silicon, the observed decreased radiation resistance with decreased resistivity is attributed to the presence of a radiation-induced boron-oxygen defect. Comparison of radiation damage in both p+n and n+p GaAs cells yields a decreased radiation resistance for the n+p cell attributable to increased series resistance, decreased shunt resistance, and relatively greater losses in the cell's p-region. For InP, the n+p configuration is found to have greater radiation resistance than the p+n cell. The increased loss in this latter cell is attributed to losses in the cell's emitter region. Temperature dependency results are interpreted using a theoretical relation for dVoc/dT, which predicts that increased Voc should result in decreased numerical values for dPm/dT. The predicted correlation is observed for GaAs but not for InP, a result which is attributed to variations in cell processing.

  20. Radiation and temperature effects in gallium arsenide, indium phosphide and silicon solar cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Statler, R. L.

    1987-01-01

    The effects of radiation on performance are determined for both n(+)p and p(+)n GaAs and InP cells and for silicon n(+)p cells. It is found that the radiation resistance of InP is greater than that of both GaAs and Si under 1 MeV electron irradiation. For silicon, the observed decreased radiation resistance with decreased resistivity is attributed to the presence of a radiation induced boron-oxygen defect. Comparison of radiation damage in both p(+)n and n(+)p GaAs cells yields a decreased radiation resistance for the n(+)p cell attributable to increased series resistance, decreased shunt resistance, and relatively greater losses in the cell's p-region. For InP, the n(+)p configuration is found to have greater radiation resistance than the p(+)n cell. The increased loss in this latter cell is attributed to losses in the cell's emitter region. Temperature dependency results are interpreted using a theoretical relation for dVoc/cT which predicts that increased Voc should results in decreased numerical values for dPm/dT. The predicted correlation is observed for GaAs but not for InP a result which is attributed to variations in cell processing.

  1. Use of the aluminum gallium indium tin system for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Ziebarth, Jeffrey Thomas

    The water-reactivity of Al-Ga and Al-Ga-In-Sn alloys is investigated as a means to utilize the chemical potential energy of Al to generate H2 and heat. Bulk quantities of these alloys participate in a heterogeneous reaction with water to produce H2 and alpha-Al(OH)3 (bayerite) as confirmed by gas chromatography and X-ray diffractometry, respectively. Experiments suggest the reaction is enabled by a mechanism involving multiple alloy phases, where Al solvated in a liquid phase is transported to an interface between the alloy and water resulting in the Al being consumed by reaction. Differential scanning calorimetry indicates that for the Al-Ga-In-Sn quaternary system, the temperature at which this reaction-enabling phase liquefies is 9.38°C. H2 yield data is collected from the reaction of 50 wt% Al-34 wt% Ga-11 wt% In-5 wt% Sn alloys with water and analyzed with respect to time and temperature. Samples of this composition produced an average H 2 yield of 83.8%. A fit to the data using fractional order kinetic analysis establishes the activation energy for the rate-limiting step to be 43.8 kJ/mol.

  2. 1.55 um aluminum gallium indium arsenide strained MQW laser diodes

    NASA Astrophysics Data System (ADS)

    Yang, Chi

    At the 1.55 mum eye-safe, telecommunications operating wavelength, semiconductor diode lasers must have low threshold currents and operate at high temperatures without thermoelectric coolers. Existing diode lasers in this wavelength range based on the GaInAsP/InP materials system are very sensitive to operating temperature. To obtain high temperature, high power 1.55 mum semiconductor diode lasers, the AlGaInAs/InP materials system with strained quantum well (QW) active regions was investigated with the goal of improving temperature performance. A set of lasers with active regions consisting of different numbers of QWs (2 to 4) and different QW strains (1.2% and 1.6%) were designed taking into account the quaternary alloy bandgap of AlGaInAs, the effect of strain on the bandgap, and the quantum size effects within the QW. The active region growth temperature was optimized using photoluminescence intensity. The wafers were first processed into broad-area lasers and measured under pulsed injection. The characteristic threshold current temperature, T0, for all AlGaInAs lasers was higher (60-70 K) than for GaInAsP lasers. No strong dependence of temperature parameters on strain was observed, while properties varied significantly with the number of QWs. With more QWs, both internal efficiency and T0 increases, but internal loss increases, reducing the characteristic temperature of the differential efficiency T1. The results show that uncooled laser operation at 1.55 mum is very promising with strained AlGaInAs QWs. Ridge waveguide devices demonstrated low threshold and high output power as well as good temperature performance under continuous wave operation. Devices with different ridge heights were fabricated from one wafer and their performance was compared. It was found that current spreading was significant in these devices and a simple current density-versus-applied voltage analysis was developed to determine the spreading factor. The analysis shows that the current spreading was not effectively limited until etching went below the doped cladding layer. A recombination coefficient analysis was performed to investigate the effect of strain on Auger recombination predicted by theory. An indirect method to infer both the nonradiative recombination coefficient and the Auger recombination coefficient was initially used. The measured values of the recombination coefficients were consistent with theoretical predictions and measurements based on other material systems. The Auger recombination was lower than expected, indicating that Auger recombination is reduced in these strained QWs. To understand the carrier dynamics, impedance measurements were carried out for the first time in AlGaInAs strained QW lasers. A small-signal, sub-threshold equivalent circuit model was derived from the laser rate equations to model the measured laser impedance. Several characteristic carrier lifetimes were obtained directly from these electrical impedance measurements. From the temperature dependence of the QW escape time, it was found that hole rather than electron leakage is dominant in the AlGaInAs system due to the relatively low valence band offset. This may explain why the improvement of T0 in AlGaInAs QW 1.55 mum active regions is limited.

  3. Characterization and modeling of tensil-strained gallium arsenide/indium aluminum arsenic quantum wells

    NASA Astrophysics Data System (ADS)

    Meng, Qingru

    This dissertation intended to provide a foundation for the development of electroabsorptive quantum well devices based on tensile strained GaAs/InAlAs double quantum well (DQW) structures which, in turn, provide polarization insensitivity in the optical response. The effects of structural parameters and electric field on eigenstates and optical properties were examined experimentally and theoretically. A self-consistent analysis program was developed for this study. Samples used in this work were grown by solid-source MBE. The in-situ calibration of alloy composition and growth rate by reflection high energy electron diffraction (RHEED) was compared with ex-situ characterization techniques including double-crystal X-ray diffractometry (DCXD) and transmission electron microscopy (TEM). Quantum confinement effects, coupling effects, and strain effects on carrier eigenstates and interband transitions were investigated by low temperature photoluminescence (PL) and theoretical analysis. Depending on the amount of tensile strain and quantum confinement, electron-light hole transitions can be brought to the absorption edge, which is desired for achieving polarization independence in quantum well structures. Compared to single quantum well structures, the uniqueness of DQWs lies in the interaction of eigenstates in different wells through a finite potential barrier. Energy band diagrams, eigenstates, and absorption coefficients were examined theoretically as a function of electric field applied perpendicularly to the quantum well layers of tensile strained GaAs/InAlAs DQWs with various doping profiles (n-i-n and p-i-n). Low temperature PL measurements were performed on these samples under various bias conditions. It was shown that as far as polarization independence is concerned, the coupled DQW may provide some advantages over the single well. A self-consistent analysis program for tensile strained GaAs/InAlAs DQWs was developed to deal with the quasi-static condition of quantum well structures of interest. The one-dimensional Poisson and Schrodinger equations were solved self-consistently but decoupled from other device equations such as the continuity equations. The eigenstates in DQW structures were analyzed within the framework of the Bastard envelope function approximation using the transfer matrix method (TMM). The solution of Poisson's equation was obtained using a Jacobi-Newton iterator. The self-consistent solutions of eigenstates were then used to calculate the absorption of coupled quantum wells with exciton effects included. Four energy bands were included in the model, i.e.-Gamma band, X band, hh band and lh band. Fermi-Dirac statistics were used to describe the distribution of carriers. Constant quasi-Fermi potential were assumed for electrons and hole as the current flow was neglected. The same band offsets as those used in the Schrodinger equation were applied in Poisson's equation instead of using the electron affinity of the local material. The electron affinity rule is widely adopted by other models and simulators but does not match with experimental results.

  4. Electric Field-aided Selective Activation for Indium-Gallium-Zinc-Oxide Thin Film Transistors

    PubMed Central

    Lee, Heesoo; Chang, Ki Soo; Tak, Young Jun; Jung, Tae Soo; Park, Jeong Woo; Kim, Won-Gi; Chung, Jusung; Jeong, Chan Bae; Kim, Hyun Jae

    2016-01-01

    A new technique is proposed for the activation of low temperature amorphous InGaZnO thin film transistor (a-IGZO TFT) backplanes through application of a bias voltage and annealing at 130 °C simultaneously. In this ‘electrical activation’, the effects of annealing under bias are selectively focused in the channel region. Therefore, electrical activation can be an effective method for lower backplane processing temperatures from 280 °C to 130 °C. Devices fabricated with this method exhibit equivalent electrical properties to those of conventionally-fabricated samples. These results are analyzed electrically and thermodynamically using infrared microthermography. Various bias voltages are applied to the gate, source, and drain electrodes while samples are annealed at 130 °C for 1 hour. Without conventional high temperature annealing or electrical activation, current-voltage curves do not show transfer characteristics. However, electrically activated a-IGZO TFTs show superior electrical characteristics, comparable to the reference TFTs annealed at 280 °C for 1 hour. This effect is a result of the lower activation energy, and efficient transfer of electrical and thermal energy to a-IGZO TFTs. With this approach, superior low-temperature a-IGZO TFTs are fabricated successfully. PMID:27725695

  5. An indium gallium arsenide charge-coupled device (CCD) for 1-3 micron imaging

    NASA Astrophysics Data System (ADS)

    Olsen, Gregory H.; Cohen, Marshall J.

    1993-05-01

    The present program was the most ambitious and had as its primary objective the fabrication of an InGaAs resistive gate CCD with a long term goal of developing 1-3 micrometer InGaAs two dimensional imaging CCD's. The 1-3 micrometer band, at present, is ill-served for imaging. The existence of room temperature imager sensitive to this wavelength range is important for a wide variety of defense, scientific, and commercial applications. Operability at room temperature will allow the camera to be miniaturized, reduce its cost, and increase its ruggedness making it well suited for field applications. As a moderate-sensitivity thermal imager, cameras in this range will be able to detect on-coming vehicles and missiles as well as monitor manufacturing processes. The wavelength band also provides a better match to the natural illumination spectrum of the night sky providing enhance Night Vision capability. When combined with long wavelength (ca. 1.55 micrometer) illumination covert eye-safe surveillance is possible. Finally, one and two dimensional InGaAs arrays will span the gap between silicon based focal plane arrays and CCD's and middle infrared imagers and Fourier spectrometers for near infrared spectroscopic applications.

  6. Electrical Instability of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors under Ultraviolet Illumination

    NASA Astrophysics Data System (ADS)

    Lan-Feng, Tang; Hai, Lu; Fang-Fang, Ren; Dong, Zhou; Rong, Zhang; You-Dou, Zheng; Xiao-Ming, Huang

    2016-03-01

    Not Available Supported by the Key Industrial R&D Program of Jiangsu Province under Grand No BE2015155, the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Fundamental Research Funds for the Central Universities under Grant No 021014380033.

  7. Type-II indium arsenide/gallium antimonide superlattices for infrared detectors

    NASA Astrophysics Data System (ADS)

    Mohseni, Hooman

    In this work, the unique properties of type-II InAs/GaSb heterojunctions were utilized for the realization of novel infrared photodetectors with higher operating temperature, detectivity and uniformity than the commonly available infrared detectors. This effort was concentrated on two major devices: uncooled infrared detectors in the long wavelength infrared (LWIR) range, and cooled devices in the very long wavelength infrared (VLWIR) range. Uncooled infrared (IR) detectors are required for low-cost, lightweight sensor systems that have many industrial and medical applications. Commercially available uncooled IR sensors use ferroelectric or microbolometer detectors. These sensors are inherently slow and cannot detect rapid signal changes needed for high-speed infrared systems. Some of the applications which require a fast detector (tau < 30 msec) are: freespace communication, active infrared countermeasure, non-invasive medical monitoring, and LIDARs. Although photon detectors have frequency responses in the megahertz range, their high temperature detectivity is severely degraded due to high Auger recombination rates. Bandgap engineering was used in order to suppress Auger recombination at room temperature in type-II superlattices. Our experimental results demonstrated nearly one order of magnitude lower Auger recombination rate at room temperature in these type-II superlattices compared to typical intrinsic detectors, such as HgCdTe, with similar bandgap. Uncooled detectors based on the engineered superlattices showed a detectivity of 1.3 x 108g cmHz 1/2/W at 11 Et m, which is comparable to microbolometers. However, the measured response time of the detectors was more than five orders of magnitude faster than microbolometers. In parallel, devices for operation in the VLWIR were developed. High-performance infrared detectors with cutoff wavelength above 14 mum are highly needed for many space-based applications. Commonly used detectors are extrinsic silicon and HgCdTe. However, the former has to be cooled below 10K, and the latter do not have good uniformity in the VLWIR range. We demonstrated high-performance type-II superlattice photodiodes with cutoff wavelength up to 25 mum and excellent bandgap uniformity over a three-inch wafer area. Devices with a 50% cutoff wavelength of 16 mum showed a nearly 50% internal quantum efficiency and background limited infrared photodetector (BLIP) performance at T = 60 K for the first time.

  8. Gallium-doped indium oxide nanoleaves: Structural characterization, growth mechanism and optical properties

    NASA Astrophysics Data System (ADS)

    Liu, Lizhu; Chen, Yiqing; Guo, Linliang; Guo, Taibo; Zhu, Yunqing; Su, Yong; Jia, Chong; Wei, Meiqin; Cheng, Yinfen

    2011-11-01

    The novel two-dimensional (2-D) Ga-doped In2O3 nanoleaves are synthesized by a simple one-step carbonthermal evaporation method using Cu-Sn alloy as the substrates. Two basic parts construct this leaf-like nanostructure: a long central trunk and two tapered nanoribbons in symmetric distribution in relation to the trunk. The Ga-In-O alloy particles are located at or close to the tips of the central trunks and serve as catalysts for the central trunk growth by the self-catalytic vapor-liquid-solid (VLS) mechanism. And the homoepitaxial growth of tapered nanoribbon on the surface of the central trunk can be explained by vapor-solid (VS) mechanism. The room-temperature photoluminescence (PL) measurement of this nanoscaled Ga-doped In2O3 transparent conducting oxide (TCO) detected two blue peaks located at 432 nm and 481 nm, respectively, which can be used by Ru-based dye and indicates potential application in dye-sensitized solar cells (DSSCs). The successful preparation of this novel 2-D Ga-doped In2O3 nanoleaves not only enriches the synthesis of TCO materials, but also provides new blocks in future architecture of functional nano-devices.

  9. Studies of High Performance Indium Gallium Arsenide Metal-Semiconductor Photodiodes.

    NASA Astrophysics Data System (ADS)

    Gao, Wei

    1995-01-01

    The purpose of this study is to achieve high speed and high responsivity metal-semiconductor-metal (MSM) photodiodes, which includes material growth, device design, fabrication, and testing. Liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) growth were used to grow high purity InGaAs layers. To obtain high purity InGaAs layers, rare-earth elements (Yb, Ga, and Er) were used during LPE growth. The rare-earth elements react strongly with donor impurities to purify the epitaxial layers, resulting in higher mobility, lower carrier concentration, and higher photoluminescence efficiency in the rare-earth doped melt grown InGaAs layer. Unfortunately, rare-earth elements have high impurity levels and hardly interact with acceptor impurities; thus, causing undesired deep levels. Both abrupt and digital superlattice InAlAs barrier enhancement InGaAs MSM photodiodes were grown by MBE. To improve the photoresponsivity, a transparent conductive material, cadmium tin oxide (CTO) was used as the MSM contacts. The CTO functions as a Schottky contact, an optical window and an anti-reflection coating. The Schottky barrier height, which is vitally important for MSM photodiodes, was studied with CTO, ITO, Au, Ti, and Pt on InAlAs using the Norde method. The CTO MSM photodiodes showed a factor of almost two improvement in responsivity over conventional Ti/Au MSM photodiodes. Abrupt barrier enhancement MSM photodiodes using CTO and Ti/Au electrodes demonstrated 3-dB bandwidths of 0.3 and 0.8 GHz, respectively. However, digital grading of the heterojunction facilitated better carrier extraction resulting in increased bandwidths of 1.3 and 7.1 GHz, respectively, for CTO and Ti/Au. It was demonstrated that CTO possesses a low resistivity, high transparency, and good Schottky barrier height, which makes CTO a very attractive transparent conductor suitable for optoelectronic applications. Lastly, four novel structures were proposed to improve the responsivity and the bandwidth of conventional MSM photodiodes.

  10. A customizable commercial miniaturized 320×256 indium gallium arsenide shortwave infrared camera

    NASA Astrophysics Data System (ADS)

    Huang, Shih-Che; O'Grady, Matthew; Groppe, Joseph V.; Ettenberg, Martin H.; Brubaker, Robert M.

    2004-10-01

    The design and performance of a commercial short-wave-infrared (SWIR) InGaAs microcamera engine is presented. The 0.9-to-1.7 micron SWIR imaging system consists of a room-temperature-TEC-stabilized, 320x256 (25 μm pitch) InGaAs focal plane array (FPA) and a high-performance, highly customizable image-processing set of electronics. The detectivity, D*, of the system is greater than 1013 cm-√Hz/W at 1.55 μm, and this sensitivity may be adjusted in real-time over 100 dB. It features snapshot-mode integration with a minimum exposure time of 130 μs. The digital video processor provides real time pixel-to-pixel, 2-point dark-current subtraction and non-uniformity compensation along with defective-pixel substitution. Other features include automatic gain control (AGC), gamma correction, 7 preset configurations, adjustable exposure time, external triggering, and windowing. The windowing feature is highly flexible; the region of interest (ROI) may be placed anywhere on the imager and can be varied at will. Windowing allows for high-speed readout enabling such applications as target acquisition and tracking; for example, a 32x32 ROI window may be read out at over 3500 frames per second (fps). Output video is provided as EIA170-compatible analog, or as 12-bit CameraLink-compatible digital. All the above features are accomplished in a small volume < 28 cm3, weight < 70 g, and with low power consumption < 1.3 W at room temperature using this new microcamera engine. Video processing is based on a field-programmable gate array (FPGA) platform with a soft-embedded processor that allows for ease of integration/addition of customer-specific algorithms, processes, or design requirements. The camera was developed with the high-performance, space-restricted, power-conscious application in mind, such as robotic or UAV deployment.

  11. The Aqueous Geochemistry of Trivalent Rare Earth Elements, Gallium and Indium Up to 250C

    NASA Astrophysics Data System (ADS)

    Wood, S. A.

    2011-12-01

    The aqueous solution chemistry of trivalent REE, Ga and In at elevated temperatures is relevant to radioactive waste disposal,economic geology, environmental geochemistry and a variety of other applications. In each of these areas, the ability to model aqueous mass transfer of these elements is essential and dependent on the availability of high-quality thermodynamic data. There has been fairly intense study of aqueous REE complexation and REE solid-phase solubility recently. There are fewer studies of these properties for In and Ga. The available data are reviewed and discussed in this paper. Experimentally measured stability constants at elevated temperatures are available for REE complexes with acetate, chloride, fluoride, hydroxide, and sulfate. Solubility products at elevated temperatures have been determined for selected solid REE fluoride, hydroxide and phosphate phases. The experimental data show that acetate complexes are more stable and fluoride and hydroxide complexes are less stable than predicted based on extrapolation of stability constants determined at standard conditions. The measured stability constants for chloride and sulfate complexes are in reasonable agreement with predicted values. At elevated temperatures, the stabilities of both chloride and fluoride complexes decrease with increasing atomic number across the REE series. The experimental data suggest that chloride complexation is likely to be more important relative to hydroxide and fluoride complexation than predicted from extrapolations. Lack of data prevent definitive conclusions for Ga and In. However, there are some similarities of Ga and In with the REE. In particular, chloride complexes are likely to be less important for Ga than the REE and more important for In. Bisulfide complexation could conceivably play a role for In transport.

  12. Aluminium toxicokinetics: an updated minireview.

    PubMed

    Yokel, R A; McNamara, P J

    2001-04-01

    This MiniReview updates and expands the MiniReview of aluminium toxicokinetics by Wilhelm et al. published by this journal in 1990. The use of 26Al, analyzed by accelerator mass spectrometry, now enables determination of Al toxicokinetics under physiological conditions. There is concern about aluminium in drinking water. The common sources of aluminium for man are reviewed. Oral Al bioavailability from water appears to be about 0.3%. Food is the primary common source. Al bioavailability from food has not been adequately determined. Industrial and medicinal exposure, and perhaps antiperspirant use, can significantly increase absorbed aluminium. Inhalation bioavailability of airborne soluble Al appears to be about 1.5% in the industrial environment. Al may distribute to the brain from the nasal cavity, but the significance of this exposure route is unknown. Systemic Al bioavailability after single underarm antiperspirant application may be up to 0.012%. All intramuscularly injected Al, e.g. from vaccines, may eventually be absorbed. Al distributes unequally to all tissues. Distribution and renal excretion appear to be enhanced by citrate. Brain uptake of Al may be mediated by Al transferrin and Al citrate complexes. There appears to be carrier-mediated efflux of Al citrate from the brain. Elimination half-lives of years have been reported in man, probably reflecting release from bone. Al elimination is primarily renal with < or = 2% excreted in bile. The contribution of food to absorbed Al needs to be determined to advance our understanding of the major components of Al toxicokinetics.

  13. Gallium arsenide quantum well-based far infrared array radiometric imager

    NASA Technical Reports Server (NTRS)

    Forrest, Kathrine A.; Jhabvala, Murzy D.

    1991-01-01

    We have built an array-based camera (FIRARI) for thermal imaging (lambda = 8 to 12 microns). FIRARI uses a square format 128 by 128 element array of aluminum gallium arsenide quantum well detectors that are indium bump bonded to a high capacity silicon multiplexer. The quantum well detectors offer good responsivity along with high response and noise uniformity, resulting in excellent thermal images without compensation for variation in pixel response. A noise equivalent temperature difference of 0.02 K at a scene temperature of 290 K was achieved with the array operating at 60 K. FIRARI demonstrated that AlGaAS quantum well detector technology can provide large format arrays with performance superior to mercury cadmium telluride at far less cost.

  14. Gallium-doped zinc oxide films as transparent electrodes for organic solar cell applications

    NASA Astrophysics Data System (ADS)

    Bhosle, V.; Prater, J. T.; Yang, Fan; Burk, D.; Forrest, S. R.; Narayan, J.

    2007-07-01

    We report microstructural characteristics and properties of gallium-doped ZnO films deposited on glass by pulsed laser deposition. The Zn0.95Ga0.05O film deposited at 200 °C and 1×10-3 Torr showed predominant ⟨0001⟩ orientation with a metallic behavior and a resistivity of 2×10-4 Ω cm at room temperature. Low resistivity of the ZnGaO films has been explained in terms of optimal combination of carrier concentration and minimized scattering, and is correlated with the microstructure and the deposition parameters. Power conversion efficiency comparable to indium tin oxide-based devices (1.25±0.05%) is achieved on a Zn0.95Ga0.05O/Cu-phthalocyanine/C60 double-heterojunction solar cell.

  15. Gallium Nitride Nanowires and Heterostructures: Toward Color-Tunable and White-Light Sources.

    PubMed

    Kuykendall, Tevye R; Schwartzberg, Adam M; Aloni, Shaul

    2015-10-14

    Gallium-nitride-based light-emitting diodes have enabled the commercialization of efficient solid-state lighting devices. Nonplanar nanomaterial architectures, such as nanowires and nanowire-based heterostructures, have the potential to significantly improve the performance of light-emitting devices through defect reduction, strain relaxation, and increased junction area. In addition, relaxation of internal strain caused by indium incorporation will facilitate pushing the emission wavelength into the red. This could eliminate inefficient phosphor conversion and enable color-tunable emission or white-light emission by combining blue, green, and red sources. Utilizing the waveguiding modes of the individual nanowires will further enhance light emission, and the properties of photonic structures formed by nanowire arrays can be implemented to improve light extraction. Recent advances in synthetic methods leading to better control over GaN and InGaN nanowire synthesis are described along with new concept devices leading to efficient white-light emission. PMID:26032973

  16. Gallium Nitride Nanowires and Heterostructures: Toward Color-Tunable and White-Light Sources.

    PubMed

    Kuykendall, Tevye R; Schwartzberg, Adam M; Aloni, Shaul

    2015-10-14

    Gallium-nitride-based light-emitting diodes have enabled the commercialization of efficient solid-state lighting devices. Nonplanar nanomaterial architectures, such as nanowires and nanowire-based heterostructures, have the potential to significantly improve the performance of light-emitting devices through defect reduction, strain relaxation, and increased junction area. In addition, relaxation of internal strain caused by indium incorporation will facilitate pushing the emission wavelength into the red. This could eliminate inefficient phosphor conversion and enable color-tunable emission or white-light emission by combining blue, green, and red sources. Utilizing the waveguiding modes of the individual nanowires will further enhance light emission, and the properties of photonic structures formed by nanowire arrays can be implemented to improve light extraction. Recent advances in synthetic methods leading to better control over GaN and InGaN nanowire synthesis are described along with new concept devices leading to efficient white-light emission.

  17. Grip for fatigue testing pure aluminium

    NASA Astrophysics Data System (ADS)

    Lehmann, P.; Yuan, G. S.; Hartwig, K. T.

    A simple method of clamping pure aluminium for fatigue tests at cryogenic temperatures is described. Easily machined cylindrical specimens are aligned and held firmly by collet grips that counteract sample shrinkage during cooldown. Specimens are quickly mounted and removed after testing without distortion or thermal treatment 99.999% aluminium, aluminium alloys and copper were gripped successfully through tens of thousands of fully reversed tension-compression cycles at 295, 77 and 4.2 K.

  18. A biogeochemical cycle for aluminium?

    PubMed

    Exley, Christopher

    2003-09-15

    The elaboration of biogeochemical cycles for elements which are known to be essential for life has enabled a broad appreciation of the homeostatic mechanisms which underlie element essentiality. In particular they can be used effectively to identify any part played by human activities in element cycling and to predict how such activities might impact upon the lithospheric and biospheric availability of an element in the future. The same criteria were the driving force behind the construction of a biogeochemical cycle for aluminium, a non-essential element which is a known ecotoxicant and a suspected health risk in humans. The purpose of this exercise was to examine the concept of a biogeochemical cycle for aluminium and not to review the biogeochemistry of this element. The cycle as presented is rudimentary and qualitative though, even in this nascent form, it is informative and predictive and, for these reasons alone, it is deserving of future quantification. A fully fledged biogeochemical cycle for aluminium should explain the biospheric abundance of this element and whether we should expect its (continued) active involvement in biochemical evolution.

  19. Controlled Electrochemical Deformation of Liquid-Phase Gallium.

    PubMed

    Chrimes, Adam F; Berean, Kyle J; Mitchell, Arnan; Rosengarten, Gary; Kalantar-zadeh, Kourosh

    2016-02-17

    Pure gallium is a soft metal with a low temperature melting point of 29.8 °C. This low melting temperature can potentially be employed for creating optical components with changeable configurations on demand by manipulating gallium in its liquid state. Gallium is a smooth and highly reflective metal that can be readily maneuvered using electric fields. These features allow gallium to be used as a reconfigurable optical reflector. This work demonstrates the use of gallium for creating reconfigurable optical reflectors manipulated through the use of electric fields when gallium is in a liquid state. The use of gallium allows the formed structures to be frozen and preserved as long as the temperature of the metal remains below its melting temperature. The lens can be readily reshaped by raising the temperature above the melting point and reapplying an electric field to produce a different curvature of the gallium reflector. PMID:26820807

  20. Controlled Electrochemical Deformation of Liquid-Phase Gallium.

    PubMed

    Chrimes, Adam F; Berean, Kyle J; Mitchell, Arnan; Rosengarten, Gary; Kalantar-zadeh, Kourosh

    2016-02-17

    Pure gallium is a soft metal with a low temperature melting point of 29.8 °C. This low melting temperature can potentially be employed for creating optical components with changeable configurations on demand by manipulating gallium in its liquid state. Gallium is a smooth and highly reflective metal that can be readily maneuvered using electric fields. These features allow gallium to be used as a reconfigurable optical reflector. This work demonstrates the use of gallium for creating reconfigurable optical reflectors manipulated through the use of electric fields when gallium is in a liquid state. The use of gallium allows the formed structures to be frozen and preserved as long as the temperature of the metal remains below its melting temperature. The lens can be readily reshaped by raising the temperature above the melting point and reapplying an electric field to produce a different curvature of the gallium reflector.

  1. Window structure for passivating solar cells based on gallium arsenide

    NASA Technical Reports Server (NTRS)

    Barnett, Allen M. (Inventor)

    1985-01-01

    Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

  2. Control of gallium incorporation in sol–gel derived CuIn{sub (1−x)}Ga{sub x}S{sub 2} thin films for photovoltaic applications

    SciTech Connect

    Bourlier, Yoan; Cristini Robbe, Odile; Lethien, Christophe; and others

    2015-10-15

    Highlights: • CuIn{sub (1−x)}Ga{sub x}S{sub 2} thin films were prepared by sol–gel process. • Evolution of lattice parameters is characteristic of a solid solution. • Optical band gap was found to be linearly dependent on the gallium rate. - Abstract: In this paper, we report the elaboration of Cu(In,Ga)S{sub 2} chalcopyrite thin films via a sol–gel process. To reach this aim, solutions containing copper, indium and gallium complexes were prepared. These solutions were thereafter spin-coated onto the soda lime glass substrates and calcined, leading to metallic oxides thin films. Expected chalcopyrite films were finally obtained by sulfurization of oxides layers using a sulfur atmosphere at 500 °C. The rate of gallium incorporation was studied both at the solutions synthesis step and at the thin films sulfurization process. Elemental and X-ray diffraction (XRD) analyses have shown the efficiency of monoethanolamine used as a complexing agent for the preparation of CuIn{sub (1−x)}Ga{sub x}S{sub 2} thin layers. Moreover, the replacement of diethanolamine by monoethanolamine has permitted the substitution of indium by isovalent gallium from x = 0 to x = 0.4 and prevented the precipitation of copper derivatives. XRD analyses of sulfurized thin films CuIn{sub (1−x)}Ga{sub x}S{sub 2,} clearly indicated that the increasing rate of gallium induced a shift of XRD peaks, revealing an evolution of the lattice parameter in the chalcopyrite structure. These results were confirmed by Raman analyses. Moreover, the optical band gap was also found to be linearly dependent upon the gallium rate incorporated within the thin films: it varies from 1.47 eV for x = 0 to 1.63 eV for x = 0.4.

  3. Phase Change of Gallium Enables Highly Reversible and Switchable Adhesion.

    PubMed

    Ye, Zhou; Lum, Guo Zhan; Song, Sukho; Rich, Steven; Sitti, Metin

    2016-07-01

    Gallium exhibits highly reversible and switchable adhesion when it undergoes a solid-liquid phase transition. The robustness of gallium is notable as it exhibits strong performance on a wide range of smooth and rough surfaces, under both dry and wet conditions. Gallium may therefore find numerous applications in transfer printing, robotics, electronic packaging, and biomedicine. PMID:27146217

  4. Gallium Zeolites for Light Paraffin Aromatization

    SciTech Connect

    Price, G.L.; Dooley, K.M.

    1999-02-10

    The primary original goal of this project was to investigate the active state of gallium-containing MFI catalysts for light paraffin aromatization, in particular the state of gallium in the active material. Our original hypothesis was that the most active and selective materials were those which contained gallium zeolitic cations, and that previously reported conditions for the activation of gallium-containing catalysts served to create these active centers. We believed that in high silica materials such as MFI, ion-exchange is most effectively accomplished with metals in their 1+ oxidation state, both because of the sparsity of the anionic ion-exchange sites associated with the zeolite, and because the large hydration shells associated with aqueous 3+ cations hinder transport. Metals such as Ga which commonly exist in higher oxidation states need to be reduced to promote ion-exchange and this is the reason that reduction of gallium-containing catalysts for light paraffin aromatization often yields a dramatic enhancement in catalytic activity. We have effectively combined reduction with ion-exchange and we term this combined process ''reductive solid-state ion-exchange''. Our hypothesis has largely been proven true, and a number of the papers we have published directly address this hypothesis.

  5. Distribution of indium ions in indium substituted Mn-Zn ferrites

    NASA Astrophysics Data System (ADS)

    Rao, K. H.; Mendiratta, R. G.

    1983-04-01

    The variations in dc resistivity and Mossbauer line intensities for various dopant concentrations of indium in a manganese-zinc ferrite have been investigated to analyze the site occupancy of indium ions. The indium ions are observed to occupy both tetrahedral and octahedral sites throughout the whole range of concentration studied. The picture proposed on the basis of resistivity measurements has been confirmed by Mossbauer data.

  6. Chrome doped gallium arsenide evaluation

    SciTech Connect

    Pocha, M.D.; Morse, J.D.; Brazes, W.F.

    1987-10-10

    We received, for free, two sets of Chrome doped Gallium Arsenide (GaAs:Cr) wafers, one from Cominco Electronic Materials, Inc., and the other from Furakawa Electric Co., for the purpose of evaluation as potential material for high speed photoconductive detectors. In return for the free material we promised to give the two manufacturers feed back on our evaluation of these wafers. The primary purpose of this report is to present the results of our evaluation of these wafers and conclusions regarding the usefulness of heavily doped GaAs:Cr for photoconductive detectors. We have found that response times of less than 100 ps (FWHM) are possible with GaAs:Cr detectors, but that there are several time constants to the decay which result in very long ''tails'' to the impulse response of these detectors. These long tails are unacceptable for most detector applications, but there may be some special cases where GaAs:Cr could be used. 5 figs., 1 tab.

  7. Fabrication methods and applications of microstructured gallium based liquid metal alloys

    NASA Astrophysics Data System (ADS)

    Khondoker, M. A. H.; Sameoto, D.

    2016-09-01

    This review contains a comparative study of reported fabrication techniques of gallium based liquid metal alloys embedded in elastomers such as polydimethylsiloxane or other rubbers as well as the primary challenges associated with their use. The eutectic gallium–indium binary alloy (EGaIn) and gallium–indium–tin ternary alloy (galinstan) are the most common non-toxic liquid metals in use today. Due to their deformability, non-toxicity and superior electrical conductivity, these alloys have become very popular among researchers for flexible and reconfigurable electronics applications. All the available manufacturing techniques have been grouped into four major classes. Among them, casting by needle injection is the most widely used technique as it is capable of producing features as small as 150 nm width by high-pressure infiltration. One particular fabrication challenge with gallium based liquid metals is that an oxide skin is rapidly formed on the entire exposed surface. This oxide skin increases wettability on many surfaces, which is excellent for keeping patterned metal in position, but is a drawback in applications like reconfigurable circuits, where the position of liquid metal needs to be altered and controlled accurately. The major challenges involved in many applications of liquid metal alloys have also been discussed thoroughly in this article.

  8. Optical and structural properties of an Eu implanted gallium nitride quantum dots/aluminium nitride superlattice.

    PubMed

    Peres, M; Neves, A J; Monteiro, T; Magalhães, S; Franco, N; Lorenz, K; Alves, E; Damilano, B; Massies, J; Dussaigne, A; Grandjean, N

    2010-04-01

    GaN/AIN structures made of GaN quantum dots (QDs) separated by AIN spacer layers, were doped with Europium by ion implantation. Rutherford Backscattering/Channelling measurements showed that Eu is incorporated mainly on near-substitutional cation sites within the superlattice region. Only slight deterioration of the crystal quality and no intermixing of the different layers are observed after implantation and annealing. After thermal annealing, photoluminescence associated with Eu3+ ions was observed. From its behaviour under different photon energy excitation and sample temperature we concluded that the Eu-related emitting centres are located inside the GaN QDs or dispersed in the GaN and AIN buffer or spacer layers. The 624 nm PL line, associated with Eu-doped GaN QDs, shows very low thermal quenching, suggesting recombination of confined carriers through rare-earth ion excitation.

  9. Lactobacillus plantarum CCFM639 alleviates aluminium toxicity.

    PubMed

    Yu, Leilei; Zhai, Qixiao; Liu, Xiaoming; Wang, Gang; Zhang, Qiuxiang; Zhao, Jianxin; Narbad, Arjan; Zhang, Hao; Tian, Fengwei; Chen, Wei

    2016-02-01

    Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

  10. Aluminium neurotoxicity: neurobehavioural and oxidative aspects.

    PubMed

    Kumar, Vijay; Gill, Kiran Dip

    2009-11-01

    Aluminium is the most widely distributed metal in the environment and is extensively used in daily life that provides easy exposure to human beings. The exposure to this toxic metal occurs through air, food and water. However, there is no known physiological role for aluminium within the body and hence this metal may produce adverse physiological effects. Chronic exposure of animals to aluminium is associated with behavioural, neuropathological and neurochemical changes. Among them, deficits of learning and behavioural functions are most evident. Some epidemiological studies have shown poor performance in cognitive tests and a higher abundance of neurological symptoms for workers occupationally exposed to aluminium. However, in contrast to well established neurotoxic effects, neurobehavioural studies of aluminium in rodents have generally not produced consistent results. Current researches show that any impairment in mitochondrial functions may play a major role in many human disorders including neurodegenerative disorders. Being involved in the production of reactive oxygen species, aluminium may cause impairments in mitochondrial bioenergetics and may lead to the generation of oxidative stress which may lead to a gradual accumulation of oxidatively modified cellular proteins. In this review, the neuropathologies associated with aluminium exposure in terms of neurobehavioural changes have been discussed. In addition, the impact of aluminium on the mitochondrial functions has also been highlighted.

  11. Mineral resource of the month: indium

    USGS Publications Warehouse

    Tolcin, Amy C.

    2011-01-01

    Geologically, the occurrence of indium minerals is rare. The element most often occurs as a sulfide inclusion or substitutes in other base-metal minerals, including cassiterite, chalcopyrite, sphalerite and stannite. Indium’s abundance in the crust is estimated to be 0.05 parts per million, which makes it more abundant than silver, but it is so widely disseminated that it does not occur in high enough concentrations to form mineable deposits. Therefore, indium is most often recovered from byproduct residues produced during the refining of lead and zinc. But only about one-quarter of the indium mined worldwide is refined into metal, as many indium-bearing concentrates are sent to refineries that do not have the capability of recovering the metal.

  12. Gallium uptake in myositis ossificans. Potential pitfalls in diagnosis

    SciTech Connect

    Salzman, L.; Lee, V.W.; Grant, P.

    1987-04-01

    Seven cases of gallium uptake in myositis ossificans are described. Gallium scans are done frequently in paraplegics, quadriplegics, and comatose patients to look for occult infection. It is important to be aware of possible gallium uptake in myositis ossificans, particularly in the extremities, which is frequent in these patients. Gallium uptake may be present prior to any abnormalities seen on plain films or CT scans. It is important to correlate roentgenograms with abnormal gallium scans, particularly in the extremities, to avoid potential pitfalls in diagnosis and prevent unnecessary antibiotic treatment. A bone scan should be obtained whenever possible, particularly when roentgenograms are negative, to confirm the diagnosis.

  13. Aluminium Diphosphamethanides: Hidden Frustrated Lewis Pairs.

    PubMed

    Styra, Steffen; Radius, Michael; Moos, Eric; Bihlmeier, Angela; Breher, Frank

    2016-07-01

    The synthesis and characterisation of two aluminium diphosphamethanide complexes, [Al(tBu)2 {κ(2) P,P'-Mes*PCHPMes*}] (3) and [Al(C6 F5 )2 {κ(2) P,P'-Mes*PCHPMes*}] (4), and the silylated analogue, Mes*PCHP(SiMe3 )Mes* (5), are reported. The aluminium complexes feature four-membered PCPAl core structures consisting of diphosphaallyl ligands. The silylated phosphine 5 was found to be a valuable precursor for the synthesis of 4 as it cleanly reacts with the diaryl aluminium chloride [(C6 F5 )2 AlCl]2 . The aluminium complex 3 reacts with molecular dihydrogen at room temperature under formation of the acyclic σ(2) λ(3) ,σ(3) λ(3) -diphosphine Mes*PCHP(H)Mes* and the corresponding dialkyl aluminium hydride [tBu2 AlH]3 . Thus, 3 belongs to the family of so-called hidden frustrated Lewis pairs. PMID:27271936

  14. Indium Single-Ion Frequency Standard

    NASA Technical Reports Server (NTRS)

    Nagourney, Warren

    2001-01-01

    A single laser-cooled indium ion is a promising candidate for an ultimate resolution optical time or frequency standard. It can be shown that single ions from group IIIA of the periodic table (indium, thallium, etc.) can have extremely small systematic errors. In addition to being free from Doppler, transit-time and collisional shifts, these ions are also quite insensitive to perturbations from ambient magnetic and electric fields (mainly due to the use of a J=0-0 transition for spectroscopy). Of all group IIIA ions, indium seems to be the most practical, since it is heavy enough to have a tolerable intercombination cooling transition rate and (unlike thallium) has transitions which are easily accessible with frequency multiplied continuous-wave lasers. A single indium ion standard has a potential inaccuracy of one part in 10(exp 18) for integration times of 10(exp 6) seconds. We have made substantial progress during the grant period in constructing a frequency standard based upon a single indium ion. At the beginning of the grant period, single indium ions were being successfully trapped, but the lasers and optical systems were inadequate to achieve the desired goal. We have considerably improved the stability of the dye laser used to cool the ions and locked it to a molecular resonance line, making it possible to observe stable cooling-line fluorescence from a single indium ion for reasonable periods of time, as required by the demands of precision spectroscopy. We have substantially improved the single-ion fluorescence signal with significant benefits for the detection efficiency of forbidden transitions using the 'shelving' technique. Finally, we have constructed a compact, efficient UV 'clock' laser and observed 'clock' transitions in single indium ions using this laser system. We will elaborate on these accomplishments.

  15. Pressure-induced decomposition of indium hydroxide.

    PubMed

    Gurlo, Aleksander; Dzivenko, Dmytro; Andrade, Miria; Riedel, Ralf; Lauterbach, Stefan; Kleebe, Hans-Joachim

    2010-09-15

    A static pressure-induced decomposition of indium hydroxide into metallic indium that takes place at ambient temperature is reported. The lattice parameter of c-In(OH)(3) decreased upon compression from 7.977(2) to approximately 7.45 A at 34 GPa, corresponding to a decrease in specific volume of approximately 18%. Fitting the second-order Birch-Murnaghan equation of state to the obtained compression data gave a bulk modulus of 99 +/- 3 GPa for c-In(OH)(3). The c-In(OH)(3) crystals with a size of approximately 100 nm are comminuted upon compression, as indicated by the grain-size reduction reflected in broadening of the diffraction reflections and the appearance of smaller (approximately 5 nm) incoherently oriented domains in TEM. The rapid decompression of compressed c-In(OH)(3) leads to partial decomposition of indium hydroxide into metallic indium, mainly as a result of localized stress gradients caused by relaxation of the highly disordered indium sublattice in indium hydroxide. This partial decomposition of indium hydroxide into metallic indium is irreversible, as confirmed by angle-dispersive X-ray diffraction, transmission electron microscopy imaging, Raman scattering, and FTIR spectroscopy. Recovered c-In(OH)(3) samples become completely black and nontransparent and show typical features of metals, i.e., a falling absorption in the 100-250 cm(-1) region accompanied by a featureless spectrum in the 250-2500 cm(-1) region in the Raman spectrum and Drude-like absorption of free electrons in the region of 4000-8000 cm(-1) in the FTIR spectrum. These features were not observed in the initial c-In(OH)(3), which is a typical white wide-band-gap semiconductor.

  16. Radiation damage of gallium arsenide production cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Joslin, D.; Garlick, J.; Lillington, D.; Gillanders, M.; Cavicchi, B.; Scott-Monck, J.; Kachare, R.; Anspaugh, B.

    1987-01-01

    High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.

  17. Difficult diagnosis and localization of focal nesidioblastosis: clinical implications of (68)Gallium-DOTA-D-Phe(1)-Tyr(3)-octreotide PET scanning.

    PubMed

    Kim, Jae Ri; Jang, Jin-Young; Shin, Yong Chan; Cho, Young Min; Kim, Hongbeom; Kwon, Wooil; Han, Young Min; Kim, Sun-Whe

    2016-07-01

    Focal nesidioblastosis is a rare cause of endogenous hyperinsulinemic hypoglycemia in adults. Because it is difficult to localize and detect with current imaging modalities, nesidioblastosis is challenging for biliary-pancreatic surgeons. (68)Gallium-DOTA-D-Phe(1)-Tyr(3)-octreotide PET scanning and (111)indium-pentetreotide diethylene triamine pentaacetic acid octreotide scanning may be superior to conventional imaging modalities in determining the localization of nesidioblastosis. We report the successful surgical treatment of a 54-year-old woman with focal hyperplasia of the islets of Langerhans, who experienced frequent hypoglycemic symptoms and underwent various diagnostic examinations with different results. PMID:27433465

  18. Difficult diagnosis and localization of focal nesidioblastosis: clinical implications of 68Gallium-DOTA-D-Phe1-Tyr3-octreotide PET scanning

    PubMed Central

    Kim, Jae Ri; Shin, Yong Chan; Cho, Young Min; Kim, Hongbeom; Kwon, Wooil; Han, Young Min; Kim, Sun-Whe

    2016-01-01

    Focal nesidioblastosis is a rare cause of endogenous hyperinsulinemic hypoglycemia in adults. Because it is difficult to localize and detect with current imaging modalities, nesidioblastosis is challenging for biliary-pancreatic surgeons. 68Gallium-DOTA-D-Phe1-Tyr3-octreotide PET scanning and 111indium-pentetreotide diethylene triamine pentaacetic acid octreotide scanning may be superior to conventional imaging modalities in determining the localization of nesidioblastosis. We report the successful surgical treatment of a 54-year-old woman with focal hyperplasia of the islets of Langerhans, who experienced frequent hypoglycemic symptoms and underwent various diagnostic examinations with different results. PMID:27433465

  19. Electron paramagnetic resonance identification of the orthorhombic iron-indium pair in silicon

    NASA Astrophysics Data System (ADS)

    Gehlhoff, W.; Emanuelsson, P.; Omling, P.; Grimmeiss, H. G.

    1990-04-01

    A different EPR spectrum (Lu4) in silicon doped with indium and iron is reported together with an EPR spectrum previously observed by Ludwig and Woodbury. The two spectra show orthorhombic symmetry and are found to originate from the same FeIn pair. They are explained as transitions within the two Kramers doublets of an S=3/2 system with a zero-field splitting which is very large compared with the microwave energy. The ratio between the orthorhombic and axial fine-structure parameters is determined to be E/D=0.052, and the g values of the defect were found to be gz=2.09, gy=2.05, and gx=2.07(z∥<100>, and x,y∥<110>). The temperature dependence of the intensities of both spectra shows that the lower doublet corresponds to Lu4 and the upper one to the previously observed spectrum. Contrary to what has hitherto been believed, this observation implies that the axial fine-structure parameter has the same sign for the iron-indium pair as for the iron-aluminum and iron-gallium pairs.

  20. Highly efficient blue organic light emitting devices with indium-free transparent anode on flexible substrates

    SciTech Connect

    Wang, Liang; Swensen, James S.; Polikarpov, Evgueni; Matson, Dean W.; Bonham, Charles C.; Bennett, Wendy D.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

    2010-09-30

    Indium-free transparent conducting oxides may provide a lower cost solution for the transparent anode in flexible displays and energy efficient solid state lighting. We report herein a near room temperature sputtering process for generating an indium-free transparent conductive oxide (TCO) coating on a flexible substrate. Specifically, we deposited gallium-doped zinc oxide (GZO) uniformly over a 12” diameter area at room temperature on polyethylene terephthalate (PET). During deposition, the system heats to about 60oC due to the energetic sputtering conditions, without any noticeable damage to the PET substrate. The GZO films exhibit excellent physical, optical and electrical properties: roughness ~7 nm, transmittance >85% and resistivity ~ 10-3 ohm• cm. Phosphorescent blue organic light-emitting devices (OLEDs) were fabricated on these substrates with comparable performance (16% external quantum efficiency and 33 lm/W power efficiency at 1mA/cm2) to that of devices fabricated on GZO (or ITO) deposited on glass substrates, suggesting flexible GZO/PET substrates may be used instead of high-cost and rigid ITO and glass for flexible displays and solid state lighting.

  1. Laser direct patterning of indium tin oxide for defining a channel of thin film transistor.

    PubMed

    Wang, Jian-Xun; Kwon, Sang Jik; Han, Jae-Hee; Cho, Eou Sik

    2013-11-01

    In this work, using a Q-switched diode-pumped neodymium-doped yttrium vanadate (Nd:YVO4, lambda = 1064 nm) laser, a direct patterning of indium tin oxide (ITO) channel was realized on glass substrates and the results were compared and analyzed in terms of the effect of repetition rate, scanning speed on etching characteristics. The results showed that the laser conditions of 40 kHz repetition rate with a scanning speed of 500 mm/s were appropriate for the channeling of ITO electrodes. The length of laser-patterned channel was maintained at about 55 microm. However, residual spikes (about 50 nm in height) of ITO were found to be formed at the edges of the laser ablated area and a few ITO residues remained on the glass substrate after laser scanning. By dipping the laser-ablated ITO film in ITO diluted etchant (ITO etchant/DI water: 1/10) at 50 degrees C for 3 min, the spikes and residual ITO were effectively removed. At last, using the laser direct patterning, a bottom-source-drain indium gallium zinc oxide thin film transistor (IGZO-TFT) was fabricated. It is successfully demonstrated that the laser direct patterning can be utilized instead of photolithography to simplify the fabrication process of TFT channel, resulting in the increase of productivity and reduction of cost. PMID:24245327

  2. Biological indicators of exposure to total and respirable aluminium dust fractions in a primary aluminium smelter.

    PubMed Central

    Röllin, H B; Theodorou, P; Cantrell, A C

    1996-01-01

    OBJECTIVES: The study attempts to define biological indicators of aluminium uptake and excretion in workers exposed to airborne aluminium compounds in a primary aluminium smelter. Also, this study defines the total and respirable aluminium dust fractions in two different potrooms, and correlates their concentrations with biological indicators in this group of workers. METHODS: Air was sampled at defined work sites. Non-destructive and conventional techniques were used to find total and respirable aluminium content of the dust. Blood and urine was collected from 84 volunteers employed at various work stations throughout the smelter and from two different cohorts of controls matched for sex, age, and socioeconomic status. Aluminium in serum samples and urine specimens was measured by flameless atomic absorption with a PE 4100 ZL spectrometer. RESULTS: The correlation of aluminium concentrations in serum and urine samples with the degree of exposure was assessed for three arbitrary exposure categories; low (0.036 mg Al/m3), medium (0.35 mg Al/m3) and high (1.47 mg Al/m3) as found in different areas of the smelter. At medium and high exposure, the ratio of respirable to total aluminium in the dust samples varied significantly. At high exposure, serum aluminium, although significantly raised, was still within the normal range of an unexposed population. The workers with low exposure excreted aluminium in urine at levels significantly higher than the controls, but still within the normal range of the population. However, potroom workers with medium and high exposure had significantly higher urinary aluminium than the normal range. CONCLUSIONS: It is concluded that only urinary aluminium constitutes a practical index of occupational exposure at or above 0.35 mg Al/m3, and that the respirable fraction of the dust may play a major role in the biological response to exposure to aluminium in a smelter environment. PMID:8758038

  3. Aluminium electrodeposition under ambient conditions.

    PubMed

    Abbott, Andrew P; Harris, Robert C; Hsieh, Yi-Ting; Ryder, Karl S; Sun, I-Wen

    2014-07-28

    The electrodeposition of aluminium is demonstrated using a eutectic mixture of aluminium chloride and urea. The mixture is shown to be conducting through the formation of both cationic ([AlCl2·urean](+)) and anionic (AlCl4(-)) species and electrodeposition is achieved through the cationic species. The use of a biphasic system with the ionic liquid and a protective hydrocarbon layer allows metal deposition to be carried out in an environment with ambient moisture without the need for a glove box. A direct comparison is made between the AlCl3:urea and imidazolium chloride:AlCl3 systems and the differences in speciation and mass transport manifest themselves in different deposit morphologies. Brighteners which work in the chloroaluminate system such as toluene and LiCl are shown to be ineffective in the urea based system and the reasons for these differences are ascribed to the mechanism of the anodic reaction which is rate limiting. PMID:24916113

  4. Long-chain amine-templated synthesis of gallium sulfide and gallium selenide nanotubes

    NASA Astrophysics Data System (ADS)

    Seral-Ascaso, A.; Metel, S.; Pokle, A.; Backes, C.; Zhang, C. J.; Nerl, H. C.; Rode, K.; Berner, N. C.; Downing, C.; McEvoy, N.; Muñoz, E.; Harvey, A.; Gholamvand, Z.; Duesberg, G. S.; Coleman, J. N.; Nicolosi, V.

    2016-06-01

    We describe the soft chemistry synthesis of amine-templated gallium chalcogenide nanotubes through the reaction of gallium(iii) acetylacetonate and the chalcogen (sulfur, selenium) using a mixture of long-chain amines (hexadecylamine and dodecylamine) as a solvent. Beyond their role as solvent, the amines also act as a template, directing the growth of discrete units with a one-dimensional multilayer tubular nanostructure. These new materials, which broaden the family of amine-stabilized gallium chalcogenides, can be tentatively classified as direct large band gap semiconductors. Their preliminary performance as active material for electrodes in lithium ion batteries has also been tested, demonstrating great potential in energy storage field even without optimization.We describe the soft chemistry synthesis of amine-templated gallium chalcogenide nanotubes through the reaction of gallium(iii) acetylacetonate and the chalcogen (sulfur, selenium) using a mixture of long-chain amines (hexadecylamine and dodecylamine) as a solvent. Beyond their role as solvent, the amines also act as a template, directing the growth of discrete units with a one-dimensional multilayer tubular nanostructure. These new materials, which broaden the family of amine-stabilized gallium chalcogenides, can be tentatively classified as direct large band gap semiconductors. Their preliminary performance as active material for electrodes in lithium ion batteries has also been tested, demonstrating great potential in energy storage field even without optimization. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01663d

  5. A nanoparticle ink printing process for all printed thin film copper-indium-selenide (CIS) solar cells

    NASA Astrophysics Data System (ADS)

    Li, X. Charles; Soltesz, Istvan; Wu, Mindy; Ziobro, Frank; Amidon, Roger; Kiss, Zoltan

    2008-08-01

    Copper indium selenide (CIS) or its derivatives (such as gallium doped CIS and sulfur substituted CIS) are considered the best optical absorber material used in polycrystalline thin film photovoltaic solar cells due to their favorable electrical and optical properties, and long term stability. To develop a low cost yet high throughput thin film deposition process with both composition and film uniformity control, precursor ink has been formulated using nanoparticle metal oxide of copper and indium in an organic solvent system dissolved with selenium or sulfur. Smooth thin film of precursor oxide mixture has been demonstrated by wet printing process. Upon heat treatment of the precursor thin film under atmosphere of selenium and/or sulfur, copper-indium selenide and/or sulfide (CIS) was formed. Several approaches of nanoparticle ink coating processes have been investigated through spin-coating, screen-printing and contact printing. For using glass substrate, contact printing demonstrated superior uniformity and composition control. By using a post-thermal treatment process on the nanoparticle-coated film, good morphology thin film with composition control was achieved. Both the chemical composition and physical morphology has been investigated using ICP-OES and XRD measurements. Based on molybdenum glass substrate, all-printed solar cells have been demonstrated.

  6. In-situ Observation of Surface Graphitization of Gallium Droplet and Concentration of Carbon in Liquid Gallium

    NASA Astrophysics Data System (ADS)

    Ueki, Ryuichi; Nishijima, Takuya; Hikata, Takeshi; Ookubo, Soichiro; Utsunomiya, Risa; Matsuba, Teruaki; Fujita, Jun-ichi

    2012-06-01

    Although carbon has been recognized to be insoluble in gallium, we found that the outermost surface of gallium has unexpectedly high carbon solubility, particularly the limited region of about a few nanometers in depth. Our in-situ transmission electron microscope observations revealed that a graphene layer was precipitated at the surface of a gallium droplet simultaneously with gallium evaporation, and some of the droplets created an internal graphitic layer. On the basis of these experimental data, we evaluated a substantial carbon solubility that seemed to exceed about 50 at. %, but was realized in a very thin surface region of about 4 nm in depth. We believe that this high carbon solubility at the gallium surface is the key mechanism for the catalytic ability of gallium that was observed at the interface between liquid gallium and solid amorphous carbon.

  7. Synchrotron X-ray fluorescence microscopy of gallium in bladder tissue following gallium maltolate administration during urinary tract infection.

    PubMed

    Ball, Katherine R; Sampieri, Francesca; Chirino, Manuel; Hamilton, Don L; Blyth, Robert I R; Sham, Tsun-Kong; Dowling, Patricia M; Thompson, Julie

    2013-11-01

    A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 μg/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli.

  8. Synchrotron X-Ray Fluorescence Microscopy of Gallium in Bladder Tissue following Gallium Maltolate Administration during Urinary Tract Infection

    PubMed Central

    Sampieri, Francesca; Chirino, Manuel; Hamilton, Don L.; Blyth, Robert I. R.; Sham, Tsun-Kong; Dowling, Patricia M.; Thompson, Julie

    2013-01-01

    A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 μg/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli. PMID:23877680

  9. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C.; Shul, Randy J.

    1999-01-01

    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.

  10. Gallium nitride junction field-effect transistor

    DOEpatents

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

    1999-02-02

    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.

  11. Extrapulmonary localization of gallium in sarcoidosis

    SciTech Connect

    Rohatgi, P.K.; Singh, R.; Vieras, F.

    1987-01-01

    This paper describes the spectrum of extrapulmonary localization of gallium in patients with sarcoidosis. The usefulness of Ga-67 scintiscans in detecting clinically occult lesions, in directing clinicians to accessible sites for biopsy, and in following the course of extrapulmonary sites of involvement with therapy is emphasized.

  12. Gallium Electromagnetic (GEM) Thruster Performance Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

    2009-01-01

    Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

  13. Solar cell with a gallium nitride electrode

    DOEpatents

    Pankove, Jacques I.

    1979-01-01

    A solar cell which comprises a body of silicon having a P-N junction therein with a transparent conducting N-type gallium nitride layer as an ohmic contact on the N-type side of the semiconductor exposed to solar radiation.

  14. Anisotropy of the magnetic susceptibility of gallium

    USGS Publications Warehouse

    Pankey, T.

    1960-01-01

    The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25??C. The following anisotropic diamagnetic susceptibilities were found: a axis (-0.119??0. 001)??10-6 emu/g, b axis (-0.416??0.002)??10 -6 emu/g, and c axis (-0.229??0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (-0.257??0.003)??10-6 emu/g at 25??C, and (-0.299??0.003)??10-6 emu/g at -196??C. The susceptibility of liquid gallium was (0.0031??0.001) ??10-6 emu/g at 30??C and 100??C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi-energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state. ?? 1960 The American Institute of Physics.

  15. Development of gallium aluminum phosphide electroluminescent diodes

    NASA Technical Reports Server (NTRS)

    Chicotka, R. J.; Lorenz, M. R.; Nethercot, A. H.; Pettit, G. D.

    1972-01-01

    Work done on the development of gallium aluminum phosphide alloys for electroluminescent light sources is described. The preparation of this wide band gap semiconductor alloy, its physical properties (particularly the band structure, the electrical characteristics, and the light emitting properties) and work done on the fabrication of diode structures from these alloys are broadly covered.

  16. Gallium Nitride Crystals: Novel Supercapacitor Electrode Materials.

    PubMed

    Wang, Shouzhi; Zhang, Lei; Sun, Changlong; Shao, Yongliang; Wu, Yongzhong; Lv, Jiaxin; Hao, Xiaopeng

    2016-05-01

    A type of single-crystal gallium nitride mesoporous membrane is fabricated and its supercapacitor properties are demonstrated for the first time. The supercapacitors exhibit high-rate capability, stable cycling life at high rates, and ultrahigh power density. This study may expand the range of crystals as high-performance electrode materials in the field of energy storage.

  17. Gallium-positive Lyme disease myocarditis

    SciTech Connect

    Alpert, L.I.; Welch, P.; Fisher, N.

    1985-09-01

    In the course of a work-up for fever of unknown origin associated with intermittent arrhythmias, a gallium scan was performed which revealed diffuse myocardial uptake. The diagnosis of Lyme disease myocarditis subsequently was confirmed by serologic titers. One month following recovery from the acute illness, the abnormal myocardial uptake completely resolved.

  18. Alveolar proteinosis associated with aluminium dust inhalation.

    PubMed

    Chew, R; Nigam, S; Sivakumaran, P

    2016-08-01

    Secondary alveolar proteinosis is a rare lung disease which may be triggered by a variety of inhaled particles. The diagnosis is made by detection of anti-granulocyte-macrophage colony-stimulating factor antibodies in bronchoalveolar lavage fluid, which appears milky white and contains lamellar bodies. Aluminium has been suggested as a possible cause, but there is little evidence in the literature to support this assertion. We report the case of a 46-year-old former boilermaker and boat builder who developed secondary alveolar proteinosis following sustained heavy aluminium exposure. The presence of aluminium was confirmed both by histological examination and metallurgical analysis of a mediastinal lymph node. Despite cessation of exposure to aluminium and treatment with whole-lung lavage which normally results in improvements in both symptoms and lung function, the outcome was poor and novel therapies are now being used for this patient. It may be that the natural history in aluminium-related alveolar proteinosis is different, with the metal playing a mediating role in the disease process. Our case further supports the link between aluminium and secondary alveolar proteinosis and highlights the need for measures to prevent excessive aluminium inhalation in relevant industries. PMID:27099254

  19. Aluminium in Biological Environments: A Computational Approach

    PubMed Central

    Mujika, Jon I; Rezabal, Elixabete; Mercero, Jose M; Ruipérez, Fernando; Costa, Dominique; Ugalde, Jesus M; Lopez, Xabier

    2014-01-01

    The increased availability of aluminium in biological environments, due to human intervention in the last century, raises concerns on the effects that this so far “excluded from biology” metal might have on living organisms. Consequently, the bioinorganic chemistry of aluminium has emerged as a very active field of research. This review will focus on our contributions to this field, based on computational studies that can yield an understanding of the aluminum biochemistry at a molecular level. Aluminium can interact and be stabilized in biological environments by complexing with both low molecular mass chelants and high molecular mass peptides. The speciation of the metal is, nonetheless, dictated by the hydrolytic species dominant in each case and which vary according to the pH condition of the medium. In blood, citrate and serum transferrin are identified as the main low molecular mass and high molecular mass molecules interacting with aluminium. The complexation of aluminium to citrate and the subsequent changes exerted on the deprotonation pathways of its tritable groups will be discussed along with the mechanisms for the intake and release of aluminium in serum transferrin at two pH conditions, physiological neutral and endosomatic acidic. Aluminium can substitute other metals, in particular magnesium, in protein buried sites and trigger conformational disorder and alteration of the protonation states of the protein's sidechains. A detailed account of the interaction of aluminium with proteic sidechains will be given. Finally, it will be described how alumnium can exert oxidative stress by stabilizing superoxide radicals either as mononuclear aluminium or clustered in boehmite. The possibility of promotion of Fenton reaction, and production of hydroxyl radicals will also be discussed. PMID:24757505

  20. Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

    NASA Technical Reports Server (NTRS)

    Grove, C. A.; Judd, G.; Ansell, G. S.

    1972-01-01

    Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

  1. Gallium 67 scintigraphy in glomerular disease

    SciTech Connect

    Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.; Rhee, H.L.; Dunea, G.

    1988-12-01

    To evaluate the diagnostic usefulness of gallium 67 scintigraphy in glomerular disease, 45 patients with various glomerulopathies, excluding lupus nephritis and renal vasculitis, were studied. Persistent renal visualization 48 hours after the gallium injection, a positive scintigram, was graded as + (less than), ++ (equal to), and +++ (greater than) the hepatic uptake. Positive scintigrams were seen in ten of 16 cases of focal segmental glomerulosclerosis, six of 11 cases of proliferative glomerulonephritis, and one case of minimal change, and one of two cases of membranous nephropathy; also in three of six cases of sickle glomerulopathy, two cases of diabetic neuropathy, one of two cases of amyloidosis, and one case of mild chronic allograft rejection. The 25 patients with positive scans were younger than the 20 with negative scans (31 +/- 12 v 42 +/- 17 years; P less than 0.01), and exhibited greater proteinuria (8.19 +/- 7.96 v 2.9 +/- 2.3 S/d; P less than 0.01) and lower serum creatinine values (2 +/- 2 v 4.1 +/- 2.8 mg/dL; P less than 0.01). The amount of proteinuria correlated directly with the intensity grade of the gallium image (P less than 0.02), but there was no correlation between the biopsy diagnosis and the outcome of the gallium scan. It was concluded that gallium scintigraphy is not useful in the differential diagnosis of the glomerular diseases under discussion. Younger patients with good renal function and heavy proteinuria are likely to have a positive renal scintigram regardless of the underlying glomerulopathy.

  2. 40 CFR 421.190 - Applicability: Description of the secondary indium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... secondary indium subcategory. 421.190 Section 421.190 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Indium Subcategory § 421.190 Applicability: Description of the secondary indium... indium at secondary indium facilities processing spent electrolyte solutions and scrap indium metal...

  3. 40 CFR 421.190 - Applicability: Description of the secondary indium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... secondary indium subcategory. 421.190 Section 421.190 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Indium Subcategory § 421.190 Applicability: Description of the secondary indium... indium at secondary indium facilities processing spent electrolyte solutions and scrap indium metal...

  4. 40 CFR 421.190 - Applicability: Description of the secondary indium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... secondary indium subcategory. 421.190 Section 421.190 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Indium Subcategory § 421.190 Applicability: Description of the secondary indium... indium at secondary indium facilities processing spent electrolyte solutions and scrap indium metal...

  5. The meaning of aluminium exposure on human health and aluminium-related diseases.

    PubMed

    Crisponi, Guido; Fanni, Daniela; Gerosa, Clara; Nemolato, Sonia; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Faa, Gavino

    2013-02-01

    The aim of this review is to attempt to answer extremely important questions related to aluminium-related diseases. Starting from an overview on the main sources of aluminium exposure in everyday life, the principal aspects of aluminium metabolism in humans have been taken into consideration in an attempt to enlighten the main metabolic pathways utilised by trivalent metal ions in different organs. The second part of this review is focused on the available evidence concerning the pathogenetic consequences of aluminium overload in human health, with particular attention to its putative role in bone and neurodegenerative human diseases.

  6. Thermal Stability of Chelated Indium Activable Tracers

    SciTech Connect

    Chrysikopoulos, Costas; Kruger, Paul

    1986-01-21

    The thermal stability of indium tracer chelated with organic ligands ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) was measured for reservoir temperatures of 150, 200, and 240 C. Measurements of the soluble indium concentration was made as a function of time by neutron activation analysis. From the data, approximate thermal decomposition rates were estimated. At 150 C, both chelated tracers were stable over the experimental period of 20 days. At 200 C, the InEDTA concentration remained constant for 16 days, after which the thermal decomposition occurred at a measured rate constant of k = 0.09 d{sup -1}. The thermal decomposition of InNTA at 200 C showed a first order reaction with a measured rate constant of k = 0.16 d{sup -1}. At 240 C, both indium chelated tracers showed rapid decomposition with rate constants greater than 1.8 d{sup -1}. The data indicate that for geothermal reservoir with temperatures up to about 200 C, indium chelated tracers can be used effectively for transit times of at least 20 days. These experiments were run without reservoir rock media, and do not account for concomitant loss of indium tracer by adsorption processes.

  7. Indium: bringing liquid-crystal displays into focus

    USGS Publications Warehouse

    Mercer, Celestine N.

    2015-01-01

    Compared to more abundant industrial metals such as lead and zinc, information about the behavior and toxicity of indium in the environment is limited. However, many indium compounds have been proven to be toxic to animals.

  8. Indium: bringing liquid-crystal displays into focus

    USGS Publications Warehouse

    Mercer, Celestine N.

    2015-07-30

    Compared to more abundant industrial metals such as lead and zinc, information about the behavior and toxicity of indium in the environment is limited. However, many indium compounds have been proven to be toxic to animals.

  9. Indium oxide/n-silicon heterojunction solar cells

    DOEpatents

    Feng, Tom; Ghosh, Amal K.

    1982-12-28

    A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

  10. Aluminium and Alzheimer's disease: An epidemiological approach.

    PubMed

    Martyn, C N

    1990-03-01

    Epidemiological methods have an important role in the investigation of the postulated connection between exposure to aluminium and the development of Alzheimer's disease. We have examined the usefulness of existing data on prevalence and mortality as a resource for studying variations in the rate of the disease with time and geography. Unfortunately, methodological differences between prevalence surveys and errors and biases in mortality data are large. No reliable conclusions can be drawn from these data about geographical differences in rates of dementia in England and Wales nor about time trends in the disease.Aluminium salts are widely used in the UK for the treatment of drinking water. Residual aluminium concentrations vary more than ten fold between different parts of the country. We have estimated diagnostic rates of pre-senile Alzheimer's disease in seven geographical areas and examined the correlation between rates of Alzheimer's disease and water aluminium concentration. PMID:24202582

  11. The removal of iron from molten aluminium

    SciTech Connect

    Donk, H.M. van der; Nijhof, G.H.; Castelijns, C.A.M.

    1995-12-31

    In this work an overview is given about the techniques available for the removal of metallic impurities from molten aluminium. The overview is focused on the removal of iron. Also, some experimental results are given about the creation of iron-rich intermetallic compounds in an aluminium system, which are subsequently removed by gravity segregation and filtration techniques. This work is part of an ongoing research project of three major European aluminium companies who are co-operating on the subject of recycling of aluminium packaging materials recovered from household waste by means of Eddy-Current techniques. Using this technique the pick-up of some contaminating metals, particularly iron, is almost unavoidable.

  12. Indium-111 leukocyte scanning and fracture healing

    SciTech Connect

    Mead, L.P.; Scott, A.C.; Bondurant, F.J.; Browner, B.D. )

    1990-01-01

    This study was undertaken to determine the specificity of indium-111 leukocyte scans for osteomyelitis when fractures are present. Midshaft tibial osteotomies were performed in 14 New Zealand white rabbits, seven of which were infected postoperatively with Staphylococcus aureus per Norden's protocol. All 14 rabbits were scanned following injection with 75 microCi of indium 111 at 72 h after osteotomy and at weekly intervals for 4 weeks. Before the rabbits were killed, the fracture sites were cultured to document the presence or absence of infection. The results of all infected osteotomy sites were positive, whereas no positive scans were found in the noninfected osteotomies. We concluded from this study that uncomplicated fracture healing does not result in a positive indium-111 leukocyte scan.

  13. Formation of gallium microinclusions in GaAs single crystals

    SciTech Connect

    Vasilenko, N.D.; Gorbatyuk, A.Ya.; Maronchuk, I.E.

    1988-08-01

    In this report we analyze the causes of gallium microinclusion formation in gallium arsenide single crystals. We present a model in which microinclusions result from the decomposition of a supersaturated solid solution. From experimental data available in the literature and calculated kinetic parameters of the model we demonstrate that microinclusion formation in bulk single crystals follows the mechanism of homogeneous nucleation and Brownian coalescence of precipitated liquid gallium metal.

  14. Surface photovoltage spectroscopy applied to gallium arsenide surfaces

    NASA Technical Reports Server (NTRS)

    Bynik, C. E.

    1975-01-01

    The experimental and theoretical basis for surface photovoltage spectroscopy is outlined. Results of this technique applied to gallium arsenide surfaces, are reviewed and discussed. The results suggest that in gallium arsenide the surface voltage may be due to deep bulk impurity acceptor states that are pinned at the Fermi level at the surface. Establishment of the validity of this model will indicate the direction to proceed to increase the efficiency of gallium arsenide solar cells.

  15. Survey of the market, supply and availability of gallium

    SciTech Connect

    Rosi, F.D.

    1980-07-01

    The objective of this study was to assess the present consumption and supply of gallium, its potential availability in the satellite power system (SPS) implementation time frame, and commercial and new processing methods for increasing the production of gallium. Findings are reported in detail. The findings strongly suggest that with proper long range planning adequate gallium would be available from free-enterprise world supplies of bauxite for SPS implementation.

  16. Transport in indium-decorated graphene

    NASA Astrophysics Data System (ADS)

    Chandni, U.; Henriksen, Erik A.; Eisenstein, J. P.

    2015-06-01

    The electronic-transport properties of single-layer graphene that has a dilute coating of indium adatoms have been investigated. Our studies establish that isolated indium atoms donate electrons to graphene and become a source of charged impurity scattering, affecting the conductivity as well as magnetotransport properties of the pristine graphene. Notably, a positive magnetoresistance is observed over a wide density range after In doping. The low-field magnetoresistance carries signatures of quantum interference effects which are significantly altered by the adatoms.

  17. Gallium arsenide phosphide top solar cell

    SciTech Connect

    McNeely, J.B.; Barnett, A.M.

    1986-04-15

    This patent describes a tandem solar cell having a silicon solar cell for a low energy gap bottom cell and a high energy gap top cell. The improvement which a gallium arsenide phosphide top solar cell which described here is a. a transparent gallium phosphide substrate; b. a first active semiconductor layer of GaAs/sub 1-Y/P/sub Y/ and of a first conductivity type overlying the substrate; c. a second active semiconductor layer of GaAs/sub 1-X/P/sub X/ and of a second conductivity type opposite the first conductivity type overlying and forming a photovoltaic junction therewith; d. a transparent first electrical contact in ohmic contact with the substrate; and e. a transparent second electrical contact in ohmic contact with the second active semiconductor layer.

  18. Efficient water reduction with gallium phosphide nanowires

    PubMed Central

    Standing, Anthony; Assali, Simone; Gao, Lu; Verheijen, Marcel A.; van Dam, Dick; Cui, Yingchao; Notten, Peter H. L.; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.

    2015-01-01

    Photoelectrochemical hydrogen production from solar energy and water offers a clean and sustainable fuel option for the future. Planar III/V material systems have shown the highest efficiencies, but are expensive. By moving to the nanowire regime the demand on material quantity is reduced, and new materials can be uncovered, such as wurtzite gallium phosphide, featuring a direct bandgap. This is one of the few materials combining large solar light absorption and (close to) ideal band-edge positions for full water splitting. Here we report the photoelectrochemical reduction of water, on a p-type wurtzite gallium phosphide nanowire photocathode. By modifying geometry to reduce electrical resistance and enhance optical absorption, and modifying the surface with a multistep platinum deposition, high current densities and open circuit potentials were achieved. Our results demonstrate the capabilities of this material, even when used in such low quantities, as in nanowires. PMID:26183949

  19. A preliminary study of the dermal absorption of aluminium from antiperspirants using aluminium-26.

    PubMed

    Flarend, R; Bin, T; Elmore, D; Hem, S L

    2001-02-01

    Aluminium chlorohydrate (ACH), the active ingredient in many antiperspirants, was labeled with the radioisotope 26Al. The labeled ACH was then fractionated into about 100 samples using gel filtration chromatography. Each fraction was analyzed for 26Al and total aluminium content. Aluminium-26 was only detected in the fractions that also contained aluminium, which verified that the ACH was uniformly labeled. 84 mg of the labeled ACH was then applied to a single underarm of two adult subjects with blood and urine samples being collected over 7 weeks. Tape-stripping and mild washings of the skin were also collected for the first 6 days. Results indicate that only 0.012% of the applied aluminium was absorbed through the skin. At this rate, about 4 microg of aluminium is absorbed from a single use of ACH on both underarms. This is about 2.5% of the aluminium typically absorbed by the gut from food over the same time period. Therefore, a one-time use of ACH applied to the skin is not a significant contribution to the body burden of aluminium.

  20. A Gallium multiphase equation of state

    SciTech Connect

    Crockett, Scott D; Greeff, Carl

    2009-01-01

    A new SESAME multiphase Gallium equation of state (EOS) has been developed. The equation of state includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniol data. We also explore the possibility of re-freezing via dynamic means such as isentropic and shock compression.

  1. Gallium-67 imaging in muscular sarcoidosis

    SciTech Connect

    Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

    1984-07-01

    A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

  2. Gallium-67 radionuclide imaging in acute pyelonephritis

    SciTech Connect

    Mendez, G.; Morillo, G.; Alonso, M.; Isikoff, M.B.

    1980-01-01

    The symptoms and clinical course of patients with acute pyelonephritis are variable; likewise, urinalysis, blood cultures, and excretory urography may be normal or equivocal. The ability of gallium-67 to accumulate in areas of active inflammation was useful in the diagnosis of acute pyelonephritis in 12 cases. A multiplane tomographic scanner was used for imaging four of these patients. Initial experience with this scanner is also discussed.

  3. Long-chain amine-templated synthesis of gallium sulfide and gallium selenide nanotubes.

    PubMed

    Seral-Ascaso, A; Metel, S; Pokle, A; Backes, C; Zhang, C J; Nerl, H C; Rode, K; Berner, N C; Downing, C; McEvoy, N; Muñoz, E; Harvey, A; Gholamvand, Z; Duesberg, G S; Coleman, J N; Nicolosi, V

    2016-06-01

    We describe the soft chemistry synthesis of amine-templated gallium chalcogenide nanotubes through the reaction of gallium(iii) acetylacetonate and the chalcogen (sulfur, selenium) using a mixture of long-chain amines (hexadecylamine and dodecylamine) as a solvent. Beyond their role as solvent, the amines also act as a template, directing the growth of discrete units with a one-dimensional multilayer tubular nanostructure. These new materials, which broaden the family of amine-stabilized gallium chalcogenides, can be tentatively classified as direct large band gap semiconductors. Their preliminary performance as active material for electrodes in lithium ion batteries has also been tested, demonstrating great potential in energy storage field even without optimization. PMID:27221399

  4. Molecular beam epitaxy grown indium self-assembled plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Gibson, Ricky; Gehl, Michael; Sears, Jasmine; Zandbergen, Sander; Nader, Nima; Keiffer, Patrick; Hendrickson, Joshua; Arnoult, Alexandre; Khitrova, Galina

    2015-09-01

    We describe molecular beam epitaxy (MBE) growth conditions for self-assembled indium nanostructures, or islands, which allow for the tuning of the density and size of the indium nanostructures. How the plasmonic resonance of indium nanostructures is affected by the island density, size, distribution in sizes, and indium purity of the nanostructures is explored. These self-assembled nanostructures provide a platform for integration of resonant and non-resonant plasmonic structures within a few nm of quantum wells (QWs) or quantum dots (QDs) in a single process. A 4× increase in peak photoluminescence intensity is demonstrated for near-surface QDs resonantly coupled to indium nanostructures.

  5. Interstitial pulmonary disorders in indium-processing workers.

    PubMed

    Chonan, T; Taguchi, O; Omae, K

    2007-02-01

    The production of indium-tin oxide has increased, owing to the increased manufacture of liquid-crystal panels. It has been reported that interstitial pneumonia occurred in two indium-processing workers; therefore, the present study aimed to evaluate whether interstitial pulmonary disorders were prevalent among indium workers. The study was carried out in 108 male workers in the indium plant where the two interstitial pneumonia patients mentioned above were employed, and included high-resolution computed tomography (HRCT) of the lungs, pulmonary function tests and analysis of serum sialylated carbohydrate antigen KL-6 and the serum indium concentration. Significant interstitial changes were observed in 23 indium workers on HRCT and serum KL-6 was abnormally high (>500 U x mL(-1)) in 40 workers. Workers with serum indium concentrations in the highest quartile had significantly longer exposure periods, greater HRCT changes, lower diffusing capacity of the lung for carbon monoxide and higher KL-6 levels compared with those in the lowest quartile. The serum indium concentration was positively correlated with the KL-6 level and with the degree of HRCT changes. In conclusion, the results of the present study indicated that serum KL-6 and high-resolution computed tomography abnormalities were prevalent among indium workers and that these abnormalities increased with the indium burden, suggesting that inhaled indium could be a potential cause of occupational lung disease.

  6. Sinterless Formation Of Contacts On Indium Phosphide

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1995-01-01

    Improved technique makes it possible to form low-resistivity {nearly equal to 10(Sup-6) ohm cm(Sup2)} electrical contacts on indium phosphide semiconductor devices without damaging devices. Layer of AgP2 40 Angstrom thick deposited on InP before depositing metal contact. AgP2 interlayer sharply reduces contact resistance, without need for sintering.

  7. Study of the doping of thermally evaporated zinc oxide thin films with indium and indium oxide

    NASA Astrophysics Data System (ADS)

    Palimar, Sowmya; Bangera, Kasturi V.; Shivakumar, G. K.

    2013-12-01

    The present paper reports observations made on investigations carried out to study structural, optical and electrical properties of thermally evaporated ZnO thin films and their modulations on doping with metallic indium and indium oxide separately. ZnO thin film in the undoped state is found to have a very good conductivity of 90 Ω-1 cm-1 with an excellent transmittance of up to 90 % in the visible region. After doping with metallic indium, the conductivity of the film is found to be 580 Ω-1 cm-1, whereas the conductivity of indium oxide-doped films is increased up to 3.5 × 103 Ω-1 cm-1. Further, the optical band gap of the ZnO thin film is widened from 3.26 to 3.3 eV when doped with indium oxide and with metallic indium it decreases to 3.2 eV. There is no considerable change in the transmittance of the films after doping. All undoped and doped films were amorphous in nature with smooth and flat surface without significant modifications due to doping.

  8. The oxidation and surface speciation of indium and indium oxides exposed to atmospheric oxidants

    NASA Astrophysics Data System (ADS)

    Detweiler, Zachary M.; Wulfsberg, Steven M.; Frith, Matthew G.; Bocarsly, Andrew B.; Bernasek, Steven L.

    2016-06-01

    Metallic indium and its oxides are useful in electronics applications, in transparent conducting electrodes, as well as in electrocatalytic applications. In order to understand more fully the speciation of the indium and oxygen composition of the indium surface exposed to atmospheric oxidants, XPS, HREELS, and TPD were used to study the indium surface exposed to water, oxygen, and carbon dioxide. Clean In and authentic samples of In2O3 and In(OH)3 were examined with XPS to provide standard spectra. Indium was exposed to O2 and H2O, and the ratio of O2 - to OH- in the O1s XPS region was used to monitor oxidation and speciation of the surface. HREELS and TPD indicate that water dissociates on the indium surface even at low temperature, and that In2O3 forms at higher temperatures. Initially, OH- is the major species at the surface. Pure In2O3 is also OH- terminated following water exposure. Ambient pressure XPS studies of water exposure to these surfaces suggest that high water pressures tend to passivate the surface, inhibiting extensive oxide formation.

  9. Aluminium and the human breast.

    PubMed

    Darbre, P D

    2016-06-01

    The human population is exposed to aluminium (Al) from diet, antacids and vaccine adjuvants, but frequent application of Al-based salts to the underarm as antiperspirant adds a high additional exposure directly to the local area of the human breast. Coincidentally the upper outer quadrant of the breast is where there is also a disproportionately high incidence of breast cysts and breast cancer. Al has been measured in human breast tissues/fluids at higher levels than in blood, and experimental evidence suggests that at physiologically relevant concentrations, Al can adversely impact on human breast epithelial cell biology. Gross cystic breast disease is the most common benign disorder of the breast and evidence is presented that Al may be a causative factor in formation of breast cysts. Evidence is also reviewed that Al can enable the development of multiple hallmarks associated with cancer in breast cells, in particular that it can cause genomic instability and inappropriate proliferation in human breast epithelial cells, and can increase migration and invasion of human breast cancer cells. In addition, Al is a metalloestrogen and oestrogen is a risk factor for breast cancer known to influence multiple hallmarks. The microenvironment is established as another determinant of breast cancer development and Al has been shown to cause adverse alterations to the breast microenvironment. If current usage patterns of Al-based antiperspirant salts contribute to causation of breast cysts and breast cancer, then reduction in exposure would offer a strategy for prevention, and regulatory review is now justified. PMID:26997127

  10. Spin-phonon coupling and ferroelectricity in magnetoelectric gallium ferrite

    NASA Astrophysics Data System (ADS)

    Mukherjee, Somdutta

    2014-03-01

    Gallium ferrite (GaFeO3 or GFO) is a low temperature ferrimagnet and room temperature piezoelectric wherein the magnetic transition temperature (TC) could be tailored to room temperature and above by tuning the stoichiometry and processing conditions. Such tunability of the magnetic transition temperature renders GFO a unique perspective in the research of multiferroics to potentially demonstrate room temperature magnetoelectric effect attractive for futuristic digital memory applications. Recent studies in several transition metal oxides highlight the importance of spin-phonon coupling in designing novel multiferroics by means of strain induced phase transition. In the present work, we have systematically studied the evolution of phonons in good quality samples of GFO across the TC using Raman spectroscopy. Using the phonon softening behavior and nearest neighbor spin-spin correlation function below TC we estimated spin-phonon coupling strength in the magnetically ordered state. In the process, we also show, for the first time, the presence of a spin glass phase in GFO where the spin-glass transition has a signature of abrupt change in spin-phonon coupling strength. Though GFO is piezoelectric and crystallizes in polar Pc21n symmetry, its ferroelectric nature remained controversial probably due to the large leakage current in the bulk material. To address this issue, we deposited epitaxial thin film on single crystalline yttria stabilized zirconia (YSZ) substrate using indium tin oxide (ITO) as a bottom conducting layer. We demonstrate clear evidence of room temperature ferroelectricity in the thin films from the 180o phase shift of the piezoresponse upon switching the electric field. Further, suppression of dielectric anomaly in presence of an external magnetic field clearly reveals a pronounced magneto-dielectric coupling across the magnetic transition temperature. In addition, using first principles calculations we elucidate that Fe ions are not only

  11. Study of gallium nitride-based materials for light-emitting applications

    NASA Astrophysics Data System (ADS)

    Barletta, Philip

    The purpose of this study was to explore the possibility of fabricating phosphor-free white-emitting LED's based in the gallium nitride material system. The structures were to be grown using metal-organic chemical vapor deposition (MOCVD). Toward this end, a Thomas Swan Scientific close-coupled showerhead reactor was installed. The first experimental step in this project was the optimization of nominally undoped GaN. This was achieved successfully, as smooth, non-compensated, optically-active films were demonstrated. Additionally, a full on- and off-axis x-ray diffraction study showed that the crystal quality of this material compared favorably to that of published standards. Successful n- and p-type doping of GaN were also demonstrated. Device-worthy mobility and carrier concentration values were demonstrated. Atomic force microscopy of n-type material verified that the films was sufficiently smooth as to serve as a layer upon which active-layer quantum wells could be grown. Photoluminescence of both n- and p-type material was examined as well. An extensive indium gallium nitride growth study was carried out. The effects of several growth parameters on emission characteristics were presented. PL emission wavelengths as high as 561 nm were demonstrated. The issues of uniformity and indium platelet formation were also addressed. This InGaN experimental work was complemented with a series of calculations which gave the expected emission wavelength of an InGaN/GaN quantum well structure based on In content and well width. Strain, the quantum size effect, and the quantum-confined Stark effect were all factored into these calculations in order to study their individual contributions to emission wavelength values. This work concluded with an examination of white device structure and fabrication. Both two- and three-color devices were considered. Monochromtic devices emitting in the green and yellow were fabricated. The yellow device, emitting at 575nm, yielded the

  12. P-n junctions formed in gallium antimonide

    NASA Technical Reports Server (NTRS)

    Clough, R.; Richman, D.; Tietjen, J.

    1970-01-01

    Vapor phase deposition process forms a heavily doped n-region on a melt-grown p-type gallium antimonide substrate. HCl transports gallium to the reaction zone, where it combines with antimony hydride and the dopant carrier, hydrogen telluride. Temperatures as low as 400 degrees C are required.

  13. Behavior of pure gallium in water and various saline solutions.

    PubMed

    Horasawa, N; Nakajima, H; Takahashi, S; Okabe, T

    1997-12-01

    This study investigated the chemical stability of pure gallium in water and saline solutions in order to obtain fundamental knowledge about the corrosion mechanism of gallium-based alloys. A pure gallium plate (99.999%) was suspended in 50 mL of deionized water, 0.01%, 0.1% or 1% NaCl solution at 24 +/- 2 degrees C for 1, 7, or 28 days. The amounts of gallium released into the solutions were determined by atomic absorption spectrophotometry. The surfaces of the specimens were examined after immersion by x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). In the solutions containing 0.1% or more NaCl, the release of gallium ions into the solution was lowered when compared to deionized water after 28-day immersion. Gallium oxide monohydroxide was found by XRD on the specimens immersed in deionized water after 28-day immersion. XPS indicated the formation of gallium oxide/hydroxide on the specimens immersed in water or 0.01% NaCl solution. The chemical stability of pure solid gallium was strongly affected by the presence of Cl- ions in the aqueous solution.

  14. Gallium scintigraphy in bone infarction. Correlation with bone imaging

    SciTech Connect

    Armas, R.R.; Goldsmith, S.J.

    1984-01-01

    The appearance of gallium-67 images in bone infarction was studied in nine patients with sickle cell disease and correlated with the bone scan findings. Gallium uptake in acute infarction was decreased or absent with a variable bone scan uptake, and normal in healing infarcts, which showed increased uptake on bone scan. The significance of these findings is discussed.

  15. Automated realization of the gallium melting and triple points

    NASA Astrophysics Data System (ADS)

    Yan, X.; Duan, Y.; Zhang, J. T.; Wang, W.

    2013-09-01

    In order to improve the automation and convenience of the process involved in realizing the gallium fixed points, an automated apparatus, based on thermoelectric and heat pipe technologies, was designed and developed. This paper describes the apparatus design and procedures for freezing gallium mantles and realizing gallium melting and triple points. Also, investigations on the melting behavior of a gallium melting point cell and of gallium triple point cells were carried out while controlling the temperature outside the gallium point cells at 30 °C, 30.5 °C, 31 °C, and 31.5 °C. The obtained melting plateau curves show dentate temperature oscillations on the melting plateaus for the gallium point cells when thermal couplings occurred between the outer and inner liquid-solid interfaces. The maximum amplitude of the temperature fluctuations was about 1.5 mK. Therefore, the temperature oscillations can be used to indicate the ending of the equilibrium phase transitions. The duration and amplitude of such temperature oscillations depend on the temperature difference between the setting temperature and the gallium point temperature; the smaller the temperature difference, the longer the duration of both the melting plateaus and the temperature fluctuations.

  16. Repurposing of gallium-based drugs for antibacterial therapy.

    PubMed

    Bonchi, Carlo; Imperi, Francesco; Minandri, Fabrizia; Visca, Paolo; Frangipani, Emanuela

    2014-01-01

    While the occurrence and spread of antibiotic resistance in bacterial pathogens is vanishing current anti-infective therapies, the antibiotic discovery pipeline is drying up. In the last years, the repurposing of existing drugs for new clinical applications has become a major research area in drug discovery, also in the field of anti-infectives. This review discusses the potential of repurposing previously approved gallium formulations in antibacterial chemotherapy. Gallium has no proven function in biological systems, but it can act as an iron-mimetic in both prokaryotic and eukaryotic cells. The activity of gallium mostly relies on its ability to replace iron in redox enzymes, thus impairing their function and ultimately hampering cell growth. Cancer cells and bacteria are preferential gallium targets due to their active metabolism and fast growth. The wealth of knowledge on the pharmacological properties of gallium has opened the door to the repurposing of gallium-based drugs for the treatment of infections sustained by antibiotic-resistant bacterial pathogens, such as Acinetobacter baumannii or Pseudomonas aeruginosa, and for suppression of Mycobacterium tuberculosis growth. The promising antibacterial activity of gallium both in vitro and in different animal models of infection raises the hope that gallium will confirm its efficacy in clinical trials, and will become a valuable therapeutic option to cure otherwise untreatable bacterial infections.

  17. Two octanuclear gallium metallamacrocycles of topologically different connectivities.

    PubMed

    Park, Mira; John, Rohith P; Moon, Dohyun; Lee, Kyungjin; Kim, Ghyung Hwa; Lah, Myoung Soo

    2007-12-14

    Two topologically different metallamacrocycles--S8 symmetric octanuclear gallium(III) metalladiazamacrocycle and pseudo-D4 symmetric octanuclear gallium(III) metalladiazamacrocycle--could be prepared using two similar heteroditopic bridging ligands having asymmetrical tridentate-bidentate binding residues.

  18. Crossover from weak localization to anti-weak localization in indium oxide systems with wide range of resistivity

    NASA Astrophysics Data System (ADS)

    Shinozaki, B.; Hidaka, K.; Ezaki, S.; Makise, K.; Asano, T.; Tomai, S.; Yano, K.; Nakamura, H.

    2013-04-01

    We investigated the magnetoconductivity Δσ(H)≡1/ρ(H)-1/ρ(0) in a wide range of magnetic fields for three-dimensional indium oxide films doped with zinc, tin, or gallium in the range of resistivity ρ(300K) between 4.1×10-6 Ωm and 1.7×10-3 Ωm. The weak localization theory was fitted to data for Δσ(H) at various temperatures in the range 2.0 K ≤T≤50 K by the use of suitable characteristics Dτin(T) and Dτso, where D , τin, and τso are the electron diffusion constant, inelastic scattering time, and spin-orbit (s-o) scattering time, respectively. It was found that (i) for films with a large value of ρ, the sign of Δσ(H) changes from positive to negative with decreasing temperature as a precursor to an anti-weak localization effect; (ii) the ratio τso/τin decreases from ≈4000 to≈4.0 with increasing ρ; (iii) the strong ρ dependence of Dτso cannot be explained by the model with a constant atomic number Z in a formula τso∝1/Z4 proposed by Abrikozov and Gorkov Zh. Eksp. Teor. Fiz. 42, 1088 (1962); [Sov. Phys. JETP 15, 752 (1962)]. As a reason for this ρ dependence, we suggest that the s-o scattering changes with increasing ρ from light oxygen atoms to heavy atoms, i.e., indium, zinc, and gallium, because of the decrease in the number of oxygen vacancies acting as s-o scattering centers.

  19. Chemical state determination of molecular gallium compounds using XPS.

    PubMed

    Bourque, Jeremy L; Biesinger, Mark C; Baines, Kim M

    2016-05-01

    A series of molecular gallium compounds were analyzed using X-ray photoelectron spectroscopy (XPS). Specifically, the Ga 2p3/2 and Ga 3d5/2 photoelectron binding energies and the Ga L3M45M45 Auger electron kinetic energies of compounds with gallium in a range of assigned oxidation numbers and with different stabilizing ligands were measured. Auger parameters were calculated and used to generate multiple chemical speciation (or Wagner) plots that were subsequently used to characterize the novel gallium-cryptand[2.2.2] complexes that possess ambiguous oxidation numbers for gallium. The results presented demonstrate the ability of widely accessible XPS instruments to experimentally determine the chemical state of gallium centers and, as a consequence, provide deeper insights into reactivity compared to assigned oxidation and valence numbers.

  20. Nuclear microprobe imaging of gallium nitrate in cancer cells

    NASA Astrophysics Data System (ADS)

    Ortega, Richard; Suda, Asami; Devès, Guillaume

    2003-09-01

    Gallium nitrate is used in clinical oncology as treatment for hypercalcemia and for cancer that has spread to the bone. Its mechanism of antitumor action has not been fully elucidated yet. The knowledge of the intracellular distribution of anticancer drugs is of particular interest in oncology to better understand their cellular pharmacology. In addition, most metal-based anticancer compounds interact with endogenous trace elements in cells, altering their metabolism. The purpose of this experiment was to examine, by use of nuclear microprobe analysis, the cellular distribution of gallium and endogenous trace elements within cancer cells exposed to gallium nitrate. In a majority of cellular analyses, gallium was found homogeneously distributed in cells following the distribution of carbon. In a smaller number of cells, however, gallium appeared concentrated together with P, Ca and Fe within round structures of about 2-5 μm diameter located in the perinuclear region. These intracellular structures are typical of lysosomial material.

  1. Hot tearing evaluation for aluminium alloys

    NASA Astrophysics Data System (ADS)

    Brůna, Marek

    2016-06-01

    Hot tearing during solidification of aluminium alloys castings can be a serious problem. This phenomenon is well known but still insufficiently investigated. Hot tearing occurs in form of irregular cracks in metal castings that develop during solidification and cooling. The cause of hot tearing is generally attributed to the development of thermally induced tensile stresses and strains in a casting as the molten metal contracts during solidification and solid state shrinkage. Submited paper consists of two parts. The first part introduces the reader to the phenomenon of hot tearing. The second part describes newly developed method for assessing hot tearing susceptibility of aluminium alloys, and also gives the results on hot tearing for various aluminium alloys.

  2. 40 CFR 421.190 - Applicability: Description of the secondary indium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... indium at secondary indium facilities processing spent electrolyte solutions and scrap indium metal raw... secondary indium subcategory. 421.190 Section 421.190 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Indium Subcategory § 421.190 Applicability: Description of the secondary...

  3. 40 CFR 421.190 - Applicability: Description of the secondary indium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... indium at secondary indium facilities processing spent electrolyte solutions and scrap indium metal raw... secondary indium subcategory. 421.190 Section 421.190 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Indium Subcategory § 421.190 Applicability: Description of the secondary...

  4. Diamond grooving of rapidly solidified optical aluminium

    NASA Astrophysics Data System (ADS)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  5. Altered biodistribution and incidental findings on gallium and labeled leukocyte/bone marrow scans.

    PubMed

    Love, Charito; Palestro, Christopher J

    2010-07-01

    Gallium-67 citrate and labeled leukocyte imaging are established procedures for diagnosing inflammation and infection. Knowledge of the normal biodistribution of these tracers, variations, and unusual disease presentations improves the accuracy of their interpretation. During the first 24 hours after injection, the principal excretory pathway of gallium is renal; subsequently, excretion is primarily colonic. By 72 hours, approximately 75% remains in the body, equally distributed among soft tissues, liver, and bone/bone marrow. This normal distribution is subject to considerable variation. Nasopharyngeal and lacrimal gland uptake can be prominent. Breast uptake, generally faint and symmetric, is intense in hyperprolactinemic states such as pregnancy. Colonic uptake is very variable. Normally healing surgical incisions concentrate gallium for variable amounts of time. In patients receiving multiple transfusions renal, bladder, and bone activity are increased; liver and colon uptake are decreased. The contrast agent gadolinium exerts similar effects. At 24 hours after injection, the normal biodistribution of indium labeled leukocytes is limited to liver, spleen, and bone marrow. The normal biodistribution of technetium-labeled leukocytes includes, in addition to the reticuloendothelial system, colon, urinary tract, and occasionally gall bladder. Images obtained shortly after injection of labeled leukocytes show intense pulmonary activity, which decreases over time. Except in cystic fibrosis, segmental or lobar pulmonary activity indicates bacterial pneumonia. Diffuse pulmonary uptake is associated with various conditions but rarely with bacterial pneumonia. Labeled leukocytes do not accumulate in surgical wounds that heal by primary intention. They do accumulate in wounds healing by secondary intention, such as ostomies and skin grafts. Because labeled leukocytes accumulate in the bone marrow, complementary bone marrow imaging helps differentiate marrow activity from

  6. Aluminium Sheet Metal Forming at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Schneider, R.; Heine, B.; Grant, R. J.; Zouaoui, Z.

    2015-02-01

    Low-temperature forming technology offers a new potential for forming operations of aluminium wrought alloys which show a limited formability at ambient temperatures. This paper indicates the mechanical behaviour of the commercial aluminium alloys EN AW-5182 and EN AW-6016 at low temperatures. Stress-strain relationships at different temperatures were investigated through tensile testing experiments. Flow curves were extrapolated using an adapted mathematical constitutive relationship of flow stress and strain. A device which allows cupping tests at sub-zero temperatures was specially designed and a limiting dome height was determined.

  7. The Preparation and Structural Characterization of Three Structural Types of Gallium Compounds Derived from Gallium (II) Chloride

    NASA Technical Reports Server (NTRS)

    Gordon, Edward M.; Hepp, Aloysius F.; Duraj. Stan A.; Habash, Tuhfeh S.; Fanwick, Phillip E.; Schupp, John D.; Eckles, William E.; Long, Shawn

    1997-01-01

    The three compounds Ga2Cl4(4-mepy)2 (1),[GaCl2(4-mepy)4]GaCl4x1/2(4-mepy); (2) and GaCl2(4-mepy)2(S2CNEt2); (3) (4-mepy= 4-methylpyridine) have been prepared from reactions of gallium (II) chloride in 4-methylpyridine and characterized by single-crystal X-ray analysis. Small variations in the reaction conditions for gallium(II) chloride can produce crystals with substantially different structural properties. The three compounds described here encompass a neutral gallium(II) dimer in which each gallium is four-coordinate, an ionic compound containing both anionic and cationic gallium complex ions with different coordination numbers and a neutral six-coordinate heteroleptic

  8. Gallium scintigraphic pattern in lung CMV infections

    SciTech Connect

    Ganz, W.I.; Cohen, D.; Mallin, W.

    1994-05-01

    Due to extensive use of prophylactic therapy for Pneumonitis Carinii Pneumonia (PCP), Cytomegalic Viral (CMV) infection may now be the most common lung infection in AIDS patients. This study was performed to determine Gallium-67 patterns in AIDS patients with CMV. Pathology reports were reviewed in AIDS patients who had a dose of 5 to 10 mCi of Gallium-67 citrate. Analysis of images were obtained 48-72 hours later of the entire body was performed. Gallium-67 scans in 14 AIDS patients with biopsy proven CMV, were evaluated for eye, colon, adrenal, lung and renal uptake. These were compared to 40 AIDS patients without CMV. These controls had infections including PCP, Mycobacterial infections, and lymphocytic interstitial pneumonitis. 100% of CMV patients had bowel uptake greater than or equal to liver. Similar bowel activity was seen in 50% of AIDS patients without CMV. 71% had intense eye uptake which was seen in only 10% of patients without CMV. 50% of CMV patients had renal uptake compared to 5% of non-CMV cases. Adrenal uptake was suggested in 50%, however, SPECT imaging is needed for confirmation. 85% had low grade lung uptake. The low grade lung had perihilar prominence. The remaining 15% had high grade lung uptake (greater than sternum) due to superimposed PCP infection. Colon uptake is very sensitive indicator for CMV infection. However, observing eye, renal, and or adrenal uptake improved the diagnostic specificity. SPECT imaging is needed to confirm renal or adrenal abnormalities due to intense bowel activity present in 100% of cases. When high grade lung uptake is seen superimposed PCP is suggested.

  9. Gallium-67 imaging in muscular sarcoidosis

    SciTech Connect

    Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

    1984-07-01

    A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid muscle disease but is consistent with the rarity of clinical evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

  10. Indium and indium tin oxide induce endoplasmic reticulum stress and oxidative stress in zebrafish (Danio rerio).

    PubMed

    Brun, Nadja Rebecca; Christen, Verena; Furrer, Gerhard; Fent, Karl

    2014-10-01

    Indium and indium tin oxide (ITO) are extensively used in electronic technologies. They may be introduced into the environment during production, use, and leaching from electronic devices at the end of their life. At present, surprisingly little is known about potential ecotoxicological implications of indium contamination. Here, molecular effects of indium nitrate (In(NO3)3) and ITO nanoparticles were investigated in vitro in zebrafish liver cells (ZFL) cells and in zebrafish embryos and novel insights into their molecular effects are provided. In(NO3)3 led to induction of endoplasmic reticulum (ER) stress response, induction of reactive oxygen species (ROS) and induction of transcripts of pro-apoptotic genes and TNF-α in vitro at a concentration of 247 μg/L. In(NO3)3 induced the ER stress key gene BiP at mRNA and protein level, as well as atf6, which ultimately led to induction of the important pro-apoptotic marker gene chop. The activity of In(NO3)3 on ER stress induction was much stronger than that of ITO, which is explained by differences in soluble free indium ion concentrations. The effect was also stronger in ZFL cells than in zebrafish embryos. Our study provides first evidence of ER stress and oxidative stress induction by In(NO3)3 and ITO indicating a critical toxicological profile that needs further investigation.

  11. Tracking the Sources of Indium to the Environment

    NASA Astrophysics Data System (ADS)

    White, S. O.; Hemond, H.

    2009-12-01

    Indium is an important metal whose production is increasing dramatically due to new uses in the rapidly growing electronics, photovoltaic, and LED industries. Little is known about the natural or industrial cycling of indium, and although toxicity has been shown, toxicological data is incomplete and indium is not currently regulated in the United States. A review of the literature has shown that industrial releases of indium to the environment presently dominate natural fluxes. Mining and coal burning are the primary industrial sources of indium to the environment, with releases from the semiconductor industry small at present. This scenario may change with the rapid growth of semiconductor industries. In order to quantify releases of indium to the environment, it may be useful to exploit differences in the ratio of indium’s two stable isotopes, indium-113 and indium-115, from various sources. This method of source-tracking has proven useful for elements such as lead, where pollutant sources have significantly different isotopic ratios. Few measurements of indium isotopes have been published, and are mainly for purified indium metal or indium compounds; none are for environmental samples. The most recent measurements have shown 95.67 - 95.77% indium-115 and 4.23 - 4.33% indium-113, suggesting a range of natural isotopic abundances of at least 25 per mil. Our own measurements of highly purified, semiconductor grade indium show 95.9% indium-115 and 4.1% indium-113, indicating this range may be even larger. However, while the differences may be attributed to natural variation in isotopic ratios due to source differences or fractionation during processing, they could also be due to analytical error such as instrument fractionation. No isotopic reference material apparently exists with which to normalize measurements, therefore the reporting of absolute isotope percentages and lab-to-lab comparisons are difficult. Additionally, we have seen only a 0.5 per mil

  12. Indium-111 autologous leukocyte imaging in pancreatitis

    SciTech Connect

    Anderson, J.R.; Spence, R.A.; Laird, J.D.; Ferguson, W.R.; Kennedy, T.L.

    1986-03-01

    Thirty-nine patients with acute pancreatitis have been assessed using a prognostic factor grading system, abdominal ultrasound, and autologous leukocyte imaging. Both prognostic factor grading and leukocyte imaging can accurately assess the severity of the disease early in its course. All patients with a negative indium-labeled leukocyte image recovered without sequelae, whereas five of the 12 patients with a positive image developed complications, including two deaths. Abdominal ultrasound is of no value in assessing severity, but is a useful method of detecting those patients with gallstone-associated disease. In patients with suspected abscess formation following acute pancreatitis, indium leukocyte imaging does not differentiate between fat necrosis and abscess formation. In this situation, computerized tomography should be carried out before laparotomy is undertaken.

  13. Electroplated indium bump arrays and the bonding reliability

    NASA Astrophysics Data System (ADS)

    Qiuping, Huang; Gaowei, Xu; Gang, Quan; Yuan, Yuan; Le, Luo

    2010-11-01

    A novel electroplating indium bumping process is described, as a result of which indium bump arrays with a pitch of 100 μm and a diameter of 40 μm were successfully prepared. UBM (under bump metallization) for indium bumping was investigated with an XRD technique. The experimental results indicate that Ti/Pt (300 Å / 200 Å) has an excellent barrier effect both at room temperature and at 200 °C. The bonding reliability of the indium bumps was evaluated by a shear test. Results show that the shear strength of the indium bump significantly increases after the first reflow and then changes slowly with increasing reflow times. Such a phenomenon may be caused by the change in textures of the indium after reflow. The corresponding flip-chip process is also discussed in this paper.

  14. The toxicology of indium tin oxide.

    PubMed

    Bomhard, Ernst M

    2016-07-01

    Indium tin oxide (ITO) is a technologically important semiconductor. An increasing number of cases of severe lung effects (characterized by pulmonary alveolar proteinosis and/or interstitial fibrosis) in ITO-exposed workers warrants a review of the toxicological hazards. Short- and long-term inhalation studies in rats and mice revealed persistent alveolar proteinosis, inflammation and fibrosis in the lungs down to concentrations as low as 0.01mg/m(3). In rats, the incidences of bronchiolo-alveolar adenomas and carcinomas were significantly increased at all concentrations. In mice, ITO was not carcinogenic. A few bronchiolo-alveolar adenomas occurring after repeated intratracheal instillation of ITO to hamsters have to be interpreted as treatment-related. In vitro and in vivo studies on the formation of reactive oxygen species suggest epigenetic effects as cause of the lung tumor development. Repeated intratracheal instillation of ITO to hamsters slightly affected the male sexual organs, which might be interpreted as a secondary effect of the lung damage. Epidemiological and medical surveillance studies, serum/blood indium levels in workers as well as data on the exposure to airborne indium concentrations indicate a need for measures to reduce exposure at ITO workplaces. PMID:27343753

  15. Improvements in the realization of the ITS-90 over the temperature range from the melting point of gallium to the freezing point of silver at NIM

    SciTech Connect

    Sun, J.; Zhang, J. T.; Ping, Q.

    2013-09-11

    The temperature primary standard over the range from the melting point of gallium to the freezing point of silver in National institute of Metrology (NIM), China, was established in the early 1990s. The performance of all of fixed-point furnaces degraded and needs to be updated due to many years of use. Nowadays, the satisfactory fixed point materials can be available with the development of the modern purification techniques. NIM plans to use a group of three cells for each defining fixed point temperature. In this way the eventual drift of individual cells can be evidenced by periodic intercomparison and this will increase the reliability in disseminating the ITS-90 in China. This article describes the recent improvements in realization of ITS-90 over temperature range from the melting point of gallium to the freezing point of silver at NIM. Taking advantages of the technological advances in the design and manufacture of furnaces, the new three-zone furnaces and the open-type fixed points were developed from the freezing point of indium to the freezing point of silver, and a furnace with the three-zone semiconductor cooling was designed to automatically realize the melting point of gallium. The reproducibility of the new melting point of gallium and the new open-type freezing points of In, Sn, Zn. Al and Ag is improved, especially the freezing points of Al and Ag with the reproducibility of 0.2mK and 0.5mK respectively. The expanded uncertainty in the realization of these defining fixed point temperatures is 0.34mK, 0.44mK, 0.54mK, 0.60mK, 1.30mK and 1.88mK respectively.

  16. Aluminium in Alzheimer's disease: are we still at a crossroad?

    PubMed

    Gupta, Veer Bala; Anitha, S; Hegde, M L; Zecca, L; Garruto, R M; Ravid, R; Shankar, S K; Stein, R; Shanmugavelu, P; Jagannatha Rao, K S

    2005-01-01

    Aluminium, an environmentally abundant non-redox trivalent cation has long been implicated in the pathogenesis of Alzheimer's disease (AD). However, the definite mechanism of aluminium toxicity in AD is not known. Evidence suggests that trace metal homeostasis plays a crucial role in the normal functioning of the brain, and any disturbance in it can exacerbate events associated with AD. The present paper reviews the scientific literature linking aluminium with AD. The focus is on aluminium levels in brain, region-specific and subcellular distribution, its relation to neurofibrillary tangles, amyloid beta, and other metals. A detailed mechanism of the role of aluminium in oxidative stress and cell death is highlighted. The importance of complex speciation chemistry of aluminium in relation to biology has been emphasized. The debatable role of aluminium in AD and the cross-talk between aluminium and genetic susceptibility are also discussed. Finally, it is concluded based on extensive literature that the neurotoxic effects of aluminium are beyond any doubt, and aluminium as a factor in AD cannot be discarded. However, whether aluminium is a sole factor in AD and whether it is a factor in all AD cases still needs to be understood.

  17. Non-Stoichiometric Amorphous Indium Selenide Thin Films as a Buffer Layer for CIGS Solar Cells with Various Temperatures in Rapid Thermal Annealing.

    PubMed

    Yoo, Myoung Han; Kim, Nam-Hoon

    2016-05-01

    The conventional structure of most of copper indium gallium diselenide (Culn(1-x)Ga(x)Se2, CIGS) solar cells includes a CdS thin film as a buffer layer. Cd-free buffer layers have attracted great interest for use in photovoltaic applications to avoid the use of hazardous and toxic materials. The RF magnetron sputtering method was used with an InSe2 compound target to prepare the indium selenide precursor. Rapid thermal annealing (RTA) was conducted in ambient N2 gas to control the concentration of volatile Se from the precursor with a change in temperature. The nature of the RTA-treated indium selenide thin films remained amorphous under annealing temperatures of ≤ 700 degrees C. The Se concentration of the RTA-treated specimens demonstrated an opposite trend to the annealing temperature. The optical transmittance and band gap energies were 75.33% and 2.451-3.085 eV, respectively, and thus were suitable for the buffer layer. As the annealing temperature increased, the resistivity decreased by an order-of-magnitude from 10(4) to 10(1) Ω-cm. At lower Se concentrations, the conductivity abruptly changed from p-type to n-type without crystallite formation in the amorphous phase, with the carrier concentration in the order of 10(17) cm(-3). PMID:27483873

  18. Method for vacuum baking indium in-situ

    NASA Astrophysics Data System (ADS)

    Adamski, J. A.

    1985-12-01

    This invention pertains to a method for producing highly pure indium for subsequent utilization as a reaction component in the synthesis of polycrystalline indium phosphide which includes the step of heating raw indium under vaccuum in an open ended quartz ampoule to a temperature in excess of 850 C, followed by the step of sealing the ampoule while simultaneously maintaining the vacuum in the interior of the ampoule.

  19. Assessment of gallium-67 scanning in pulmonary and extrapulmonary sarcoidosis

    SciTech Connect

    Israel, H.L.; Gushue, G.F.; Park, C.H.

    1986-01-01

    Gallium-67 scans have been widely employed in patients with sarcoidosis as a means of indicating alveolitis and the need for corticosteroid therapy. Observation of 32 patients followed 3 or more years after gallium scans showed no correlation between findings and later course: of 10 patients with pulmonary uptake, 7 recovered with minor residuals; of 18 patients with mediastinal of extrathoracic uptake, 10 had persistent or progressive disease; of 4 patients with negative initial scans, 2 had later progression. The value of gallium-67 scans as an aid to diagnosis was studied in 40 patients with extrapulmonary sarcoidosis. In 12 patients, abnormal lacrimal, nodal, or pulmonary uptake aided in selection of biopsy sites. Gallium-67 scans and serum ACE levels were compared in 97 patients as indices of clinical activity. Abnormal gallium-67 uptake was observed in 96.3% of the tests in active disease, and ACE level elevation occurred in 56.3%. In 24 patients with inactive or recovered disease, abnormal gallium-67 uptake occurred in 62.5% and ACE level elevation in 37.5%. Gallium-67 scans have a limited but valuable role in the diagnosis and management of sarcoidosis.

  20. Gallium induces the production of virulence factors in Pseudomonas aeruginosa.

    PubMed

    García-Contreras, Rodolfo; Pérez-Eretza, Berenice; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Coria-Jiménez, Rafael; Rangel-Vega, Adrián; Maeda, Toshinari; Wood, Thomas K

    2014-02-01

    The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by competing with iron, we hypothesized that it ultimately will lead cells to an iron deficiency status. As iron deficiency promotes the expression of virulence factors in vitro and promotes the pathogenicity of P. aeruginosa in animal models, it is anticipated that treatment with gallium will also promote the production of virulence factors. To test this hypothesis, the reference strain PA14 and two clinical isolates from patients with cystic fibrosis were exposed to gallium, and their production of pyocyanin, rhamnolipids, elastase, alkaline protease, alginate, pyoverdine, and biofilm was determined. Gallium treatment induced the production of all the virulence factors tested in the three strains except for pyoverdine. In addition, as the Ga-induced virulence factors are quorum sensing controlled, co-administration of Ga and the quorum quencher brominated furanone C-30 was assayed, and it was found that C-30 alleviated growth inhibition from gallium. Hence, adding both C-30 and gallium may be more effective in the treatment of P. aeruginosa infections.

  1. Compatibility of ITER candidate structural materials with static gallium

    SciTech Connect

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

    1993-12-01

    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.

  2. The effects of gallium nitrate on bone resorption.

    PubMed

    Bockman, Richard

    2003-04-01

    Gallium nitrate has been shown to be an effective treatment for patients with cancer-related hypercalcemia. Clinical studies have also suggested the drug may have considerably broader use in other diseases associated with accelerated bone loss including multiple myeloma, bone metastases, Paget's disease, and osteoporosis. The actions of gallium nitrate on bone are quite distinct from those of bisphosphonates. Preclinical studies show that gallium preferentially accumulates in trace amounts in metabolically active regions of bone. When present, gallium favorably alters the mineral properties to enhance hydroxyapatite crystallization and reduce mineral solubility. The drug also acts on the cellular components of bone to reduce bone resorption by decreasing acid secretion by osteoclasts. This effect appears to be mediated by inhibition of the ATPase-dependent proton pump of the osteoclast's ruffled membrane. Gallium does not inhibit the development or recruitment of osteoclasts to bone tissue, unlike many bisphosphonates that may induce osteoclast apoptosis. Together, these pharmacologic actions may yield a skeletal system with increased calcium and phosphate content and improved biomechanical strength. Gallium nitrate has potent antiresorptive effects on bone that can be achieved at considerably lower doses than are currently used for cancer-related hypercalcemia. Parenteral and oral formulations of gallium appear to have high activity in bone resorptive disorders, and thus development should be vigorously pursued in these diseases. PMID:12776254

  3. Two-photon excitation of aluminium phthalocyanines

    SciTech Connect

    Meshalkin, Yu P; Alfimov, E E; Makukha, V K; Vasil'ev, N E; Denisov, A N; Ogirenko, A P

    1999-12-31

    A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined. (lasers in medicine)

  4. Molecular breeding of cereals for aluminium resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al3+) toxicity is the primary factor limiting crop production on acidic soils worldwide. In addition to an application of lime for soil amelioration, Al3+ resistant plant varieties have been deployed to raise productivity on such hostile soils. This has been possible due to the exploita...

  5. InP (Indium Phosphide): Into the future

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr.

    1989-01-01

    Major industry is beginning to be devoted to indium phosphide and its potential applications. Key to these applications are high speed and radiation tolerance; however the high cost of indium phosphide may be an inhibitor to progress. The broad applicability of indium phosphide to many devices will be discussed with an emphasis on photovoltaics. Major attention is devoted to radiation tolerance and means of reducing cost of devices. Some of the approaches applicable to solar cells may also be relevant to other devices. The intent is to display the impact of visionary leadership in the field and enable the directions and broad applicability of indium phosphide.

  6. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    PubMed

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

  7. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    PubMed

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

  8. Method to Improve Indium Bump Bonding via Indium Oxide Removal Using a Multi-Step Plasma Process

    NASA Technical Reports Server (NTRS)

    Greer, H. Frank (Inventor); Jones, Todd J. (Inventor); Vasquez, Richard P. (Inventor); Hoenk, Michael E. (Inventor); Dickie, Matthew R. (Inventor); Nikzad, Shouleh (Inventor)

    2012-01-01

    A process for removing indium oxide from indium bumps in a flip-chip structure to reduce contact resistance, by a multi-step plasma treatment. A first plasma treatment of the indium bumps with an argon, methane and hydrogen plasma reduces indium oxide, and a second plasma treatment with an argon and hydrogen plasma removes residual organics. The multi-step plasma process for removing indium oxide from the indium bumps is more effective in reducing the oxide, and yet does not require the use of halogens, does not change the bump morphology, does not attack the bond pad material or under-bump metallization layers, and creates no new mechanisms for open circuits.

  9. Surface Composition, Work Function, and Electrochemical Characteristics of Gallium-Doped Zinc Oxide

    SciTech Connect

    Ratcliff, E. L.; Sigdel, A. K.; Macech, M. R.; Nebesny, K.; Lee, P. A.; Ginley, D. S.; Armstrong, N. R.; Berry, J. J.

    2012-06-30

    Gallium-doped zinc oxide (GZO) possesses the electric conductivity, thermal stability, and earth abundance to be a promising transparent conductive oxide replacement for indium tin oxide electrodes in a number of molecular electronic devices, including organic solar cells and organic light emitting diodes. The surface chemistry of GZO is complex and dominated by the hydrolysis chemistry of ZnO, which influences the work function via charge transfer and band bending caused by adsorbates. A comprehensive characterization of the surface chemical composition and electrochemical properties of GZO electrodes is presented, using both solution and surface adsorbed redox probe molecules. The GZO surface is characterized using monochromatic X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy after the following pretreatments: (i) hydriodic acid etch, (ii) potassium hydroxide etch, (iii) RF oxygen plasma etching, and (iv) high-vacuum argon-ion sputtering. The O 1s spectra for the GZO electrodes have contributions from the stoichiometric oxide lattice, defects within the lattice, hydroxylated species, and carbonaceous impurities, with relative near-surface compositions varying with pretreatment. Solution etching procedures result in an increase of the work function and ionization potential of the GZO electrode, but yield different near surface Zn:Ga atomic ratios, which significantly influence charge transfer rates for a chemisorbed probe molecule. The near surface chemical composition is shown to be the dominant factor in controlling surface work function and significantly influences the rate of electron transfer to both solution and tethered probe molecules.

  10. Near-infrared electroluminescence at room temperature from neodymium-doped gallium nitride thin films

    SciTech Connect

    Kim, Joo Han; Holloway, Paul H.

    2004-09-06

    Strong near-infrared (NIR) electroluminescence (EL) at room temperature from neodymium (Nd)-doped gallium nitride (GaN) thin films is reported. The Nd-doped GaN films were grown by radio-frequency planar magnetron cosputtering of separate GaN and metallic Nd targets in a pure nitrogen ambient. X-ray diffraction data did not identify the presence of any secondary phases and revealed that the Nd-doped GaN films had a highly textured wurtzite crystal structure with the c-axis normal to the surface of the film. The EL devices were fabricated with a thin-film multilayered structure of Al/Nd-doped GaN/Al{sub 2}O{sub 3}-TiO{sub 2}/indium-tin oxide and tested at room temperate. Three distinct NIR EL emission peaks were observed from the devices at 905, 1082, and 1364 nm, arising from the radiative relaxation of the {sup 4}F{sub 3sol2} excited-state energy level to the {sup 4}I{sub 9sol2}, {sup 4}I{sub 11sol2}, and {sup 4}I{sub 13sol2} levels of the Nd{sup 3+} ion, respectively. The threshold voltage for all the three emission peaks was {approx}150 V. The external power efficiency of the fabricated EL devices was {approx}1x10{sup -5} measured at 40 V above the threshold voltage.

  11. Nonpolar m-plane gallium Nitride-based Laser Diodes in the Blue Spectrum

    NASA Astrophysics Data System (ADS)

    Kelchner, Kathryn M.

    Gallium nitride (GaN), together with its alloys with aluminum and indium, have revolutionized the solid-state optoelectronics market for their ability to emit a large portion of the visible electromagnetic spectrum from deep ultraviolet and into the infrared. GaN-based semiconductor laser diodes (LDs) with emission wavelengths in the violet, blue and green are already seeing widespread implementation in applications ranging from energy storage, lighting and displays. However, commercial GaN-based LDs use the basal c-plane orientation of the wurtzite crystal, which can suffer from large internal electric fields due to discontinuities in spontaneous and piezoelectric polarizations, limiting device performance. The nonpolar orientation of GaN benefits from the lack of polarization-induced electric field as well as enhanced gain. This dissertation discusses some of the benefits and limitations of m-plane oriented nonpolar GaN for LD applications in the true blue spectrum (450 nm). Topics include an overview of material growth by metal-organic chemical vapor deposition (MOCVD), waveguide design and processing techniques for improving device performance for multiple lateral mode and single lateral mode ridge waveguides.

  12. Limiting pump intensity for sulfur-doped gallium selenide crystals

    NASA Astrophysics Data System (ADS)

    Guo, J.; Li, D.-J.; Xie, J.-J.; Zhang, L.-M.; Feng, Z.-S.; Andreev, Yu M.; Kokh, K. A.; Lanskii, G. V.; Potekaev, A. I.; Shaiduko, A. V.; Svetlichnyi, V. A.

    2014-05-01

    High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium selenide).

  13. Toxicity and aluminium concentration in bone following dietary administration of two sodium aluminium phosphate formulations in rats.

    PubMed

    Hicks, J S; Hackett, D S; Sprague, G L

    1987-07-01

    The effects of dietary administration of the basic sodium aluminium phosphates, KASAL and KASAL II, were examined in male rats. Aluminium levels in bone were determined in order to estimate the possible aluminium deposition by these compounds. Groups of 25 male Sprague-Dawley rats were fed control diet or diets containing 30,000 ppm KASAL, 7000 or 30,000 ppm KASAL II, or 14,470 ppm aluminium hydroxide for 28 days. The mean daily aluminium doses were calculated to be 5, 141, 67, 288 or 302 mg/kg body weight/day, respectively. Neither form of KASAL induced detectable toxicity. No adverse treatment-related clinical signs were observed. Body weights and food consumptions were similar in treated and control groups. No toxicologically significant changes were observed in haematology, clinical chemistry parameters or organ weights. No treatment-related changes were observed at autopsy or in histopathological examination of collected tissues. Femurs collected at autopsy under conditions free of aluminium contamination showed no significant deposition of aluminium after dietary administration of KASAL, KASAL II or aluminium hydroxide. All aluminium values in bone were less than 1 ppm and most values were not quantifiable. Thus, dietary administration of up to 30,000 ppm of either of the basic sodium aluminium phosphate formulations caused neither toxicity nor significant deposition of aluminium in femur.

  14. Antitumor effect of novel gallium compounds and efficacy of nanoparticle-mediated gallium delivery in lung cancer.

    PubMed

    Wehrung, Daniel; Oyewumi, Moses O

    2012-02-01

    The widespread application of gallium (Ga) in cancer therapy has been greatly hampered by lack of specificity resulting in poor tumor accumulation and retention. To address the challenge, two lipophilic gallium (III) compounds (gallium hexanedione; GaH and gallium acetylacetonate; GaAcAc) were synthesized and antitumor studies were conducted in human lung adenocarcinoma (A549) cells. Nanoparticles (NPs) containing various concentrations of the Ga compounds were prepared using a binary mixture of Gelucire 44/14 and cetyl alcohol as matrix materials. NPs were characterized based on size, morphology, stability and biocompatibility. Antitumor effects of free or NP-loaded Ga compounds were investigated based on cell viability, production of reactive oxygen species and reduction of mitochondrial potential. Compared to free Ga compounds, cytotoxicity of NP-loaded Ga (5-150 microg/ml) was less dependent on concentration and incubation time (exposure) with A549 cells. NP-mediated delivery (5-150 microg Ga/ml) enhanced antitumor effects of Ga compounds and the effect was pronounced at: (i) shorter incubation times; and (ii) at low concentrations of gallium (approximately 50 microg/ml) (p < 0.0006). Additional studies showed that NP-mediated Ga delivery was not dependent on transferrin receptor uptake mechanism (p > 0.13) suggesting the potential in overcoming gallium resistance in some tumors. In general, preparation of stable and biocompatible NPs that facilitated Ga tumor uptake and antitumor effects could be effective in gallium-based cancer therapy.

  15. Measurement of arsenic and gallium content of gallium arsenide semiconductor waste streams by ICP-MS.

    PubMed

    Torrance, Keith W; Keenan, Helen E; Hursthouse, Andrew S; Stirling, David

    2010-01-01

    The chemistry of semiconductor wafer processing liquid waste, contaminated by heavy metals, was investigated to determine arsenic content. Arsenic and gallium concentrations were determined for waste slurries collected from gallium arsenide (GaAs) wafer processing at three industrial sources and compared to slurries prepared under laboratory conditions. The arsenic and gallium content of waste slurries was analyzed using inductively coupled plasma mass-spectrometry (ICP-MS) and it is reported that the arsenic content of the waste streams was related to the wafer thinning process, with slurries from wafer polishing having the highest dissolved arsenic content at over 1,900 mgL(-1). Lapping slurries had much lower dissolved arsenic (< 90 mgL(-1)) content, but higher particulate contents. It is demonstrated that significant percentage of GaAs becomes soluble during wafer lapping. Grinding slurries had the lowest dissolved arsenic content at 15 mgL(-1). All three waste streams are classified as hazardous waste, based on their solids content and dissolved arsenic levels and treatment is required before discharge or disposal. It is calculated that as much as 93% of material is discarded through the entire GaAs device manufacturing process, with limited recycling. Although gallium can be economically recovered from waste slurries, there is little incentive to recover arsenic, which is mostly landfilled. Options for treating GaAs processing waste streams are reviewed and some recommendations made for handling the waste. Therefore, although the quantities of hazardous waste generated are miniscule in comparison to other industries, sustainable manufacturing practices are needed to minimize the environmental impact of GaAs semiconductor device fabrication.

  16. Synthesis of conjugated polymers containing gallium atoms and evaluation of conjugation through four-coordinate gallium atoms.

    PubMed

    Matsumoto, Takuya; Onishi, Yoshinobu; Tanaka, Kazuo; Fueno, Hiroyuki; Tanaka, Kazuyoshi; Chujo, Yoshiki

    2014-12-25

    The synthesis and analysis of the electronic states of the main-chain type-organogallium polymers are presented. We synthesized the polymers containing four-coordinate gallium atoms by organometal coupling reactions. The synthesized polymers showed good solubility in common organic solvents and enough stability for measuring a series of properties under ambient conditions. In the UV-vis absorption spectra, the electronic interaction through four-coordinate gallium atoms was suggested from the peak shifts of the polymer compared to the model compounds. Theoretical calculation of these molecules supports the extended electronic interaction through the polymer main-chain involving gallium atoms.

  17. Flexible copper-indium-diselenide films and devices for space applications

    NASA Technical Reports Server (NTRS)

    Armstrong, J. H.; Pistole, C. O.; Misra, M. S.; Kapur, V. K.; Basol, B. M.

    1991-01-01

    With the ever increasing demands on space power systems, it is imperative that low cost, lightweight, reliable photovoltaics be developed. One avenue of pursuit for future space power applications is the use of low cost, lightweight flexible PV cells and arrays. Most work in this area assumes the use of flexible amorphous silicon (a-Si), despite its inherent instability and low efficiencies. However, polycrystalline thin film PV such as copper-indium-diselenide (CIS) are inherently more stable and exhibit better performance than a-Si. Furthermore, preliminary data indicate that CIS also offers exciting properties with respect to space applications. However, CIS has only heretofore only produced on rigid substrates. The implications of flexible CIS upon present and future space power platforms was explored. Results indicate that space qualified CIS can dramatically reduce the cost of PV, and in most cases, can be substituted for silicon (Si) based on end-of-life (EOL) estimations. Furthermore, where cost is a prime consideration, CIS can become cost effective than gallium arsenide (GaAs) in some applications. Second, investigations into thin film deposition on flexible substrates were made, and data from these tests indicate that fabrication of flexible CIS devices is feasible. Finally, data is also presented on preliminary TCO/CdS/CuInSe2/Mo devices.

  18. Microemulsion extraction separation and determination of aluminium species by spectrofluorimetry.

    PubMed

    Lu, Jusheng; Tian, Jiuying; Guo, Na; Wang, Yan; Pan, Yichun

    2011-01-30

    A simple and sensitive microemulsion extraction separation method was developed for the speciation of aluminium in tea samples by spectrofluorimetry. With 8-hydroxyquinoline (8-HQ) as the chelating agent and Triton X-100 Winsor II microemulsion as the extractant, separation of aluminium species in different pH solutions was achieved by microemulsion extraction. The formation of microemulsion, the conditions of extraction and determination of aluminium species were studied. The results showed that, the contents of aluminium species in tea leaves and infusions samples, such as total aluminium, total soluble aluminium, total granular aluminium, inorganic aluminium except Al-F, and (Al-F+Al-org), were obtained successfully under the optimal conditions. The limit of detection was 0.23 μg L(-1) in pH 9.5 solution, and 0.59 μg L(-1) in pH 6.0 solution respectively; the precision (RSD) for 11 replicate measurements of 10 μg L(-1) aluminium was 2.1% in pH 9.5 solution, and 2.8% in pH 6.0 solution respectively; the recoveries for the spiked samples were 96.8-103.5%. The proposed method is simple and efficient, which has been applied to the speciation of aluminium in tea samples with satisfactory results.

  19. Preliminary Experimental Measurements for a Gallium Electromagnetic (GEM) Thruster

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

    2007-01-01

    A low-energy gallium plasma source is used to perform a spatially and temporally broad spectroscopic survey in the 220-520 nm range. Neutral, singly, and doubly ionized gallium are present in a 20 J, 1.8 kA (peak) arc discharge operating with a central cathode. When the polarity of the inner electrode is reversed the discharge current and arc voltage waveforms remain similar. Utilizing a central anode configuration, multiple Ga lines are absent in the 270-340 nm range. In addition, neutral and singly ionized Fe spectral lines are present, indicating erosion of the outer electrode. With graphite present on the insulator to facilitate breakdown, line emission from the gallium species is further reduced and while emissions from singly and doubly ionized carbon atoms and molecular carbon (C2) radicals are observed. These data indicate that a significant fraction of energy is shifted from the gallium and deposited into the various carbon species.

  20. All-optical modulation in gallium arsenide integrated optical waveguides

    SciTech Connect

    McWright, G.; Ross, B.; Guthreau, W.; Lafaw, D.; Lowry, M.; Tindall, W.

    1988-01-27

    We have investigated all-optical modulators in gallium arsenide integrated optical waveguides; these modulators use electron-hole pair generation to alter the propagation characteristics of a guided light beam. 6 refs., 6 figs.

  1. Computer simulation of radiation damage in gallium arsenide

    NASA Technical Reports Server (NTRS)

    Stith, John J.; Davenport, James C.; Copeland, Randolph L.

    1989-01-01

    A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.

  2. Reversible expansion of gallium-stabilized (delta)-plutonium

    SciTech Connect

    Wolfer, W G; Oudot, B; Baclet, N

    2006-02-27

    It is shown that the transient expansion of plutonium-gallium alloys observed both in the lattice parameter as well as in the dimension of a sample held at ambient temperature can be explained by assuming incipient precipitation of Pu{sub 3}Ga. However, this ordered {zeta}-phase is also subject to radiation-induced disordering. As a result, the gallium-stabilized {delta}-phase, being metastable at ambient temperature, is driven towards thermodynamic equilibrium by radiation-enhanced diffusion of gallium and at the same time reverted back to its metastable state by radiation-induced disordering. A steady state is reached in which only a modest fraction of the gallium present is arranged in ordered {zeta}-phase regions.

  3. Reversible expansion of gallium-stabilized delta-plutonium

    SciTech Connect

    Wolfer, W; Oudot, B; Baclet, N

    2006-01-26

    The transient expansion of plutonium-gallium alloys observed both in the lattice parameter as well as in the dimension of a sample held at ambient temperature is explained by assuming incipient precipitation of Pu{sub 3}Ga. However, this ordered {zeta}{prime}-phase is also subject to radiation-induced disordering. As a result, the gallium-stabilized {delta}-phase, being metastable at ambient temperature, is both driven towards thermodynamic equilibrium by radiation-enhanced diffusion of gallium and at the same time pushed back to its metastable state by radiation-induced disordering. A steady state is reached in which only a modest fraction of the gallium present is tied up in the {zeta}{prime}-phase.

  4. Gallium scanning in Paget's disease of bone: effect of calcitonin

    SciTech Connect

    Waxman, A.D.; McKee, D.; Siemsen, J.K.; Singer, F.R.

    1980-02-01

    Calcitonin has been used in the treatment of Paget's disease of bone, and serum alkaline phosphatase level and 24 hr urinary hydroxyproline excretion have been used to follow therapeutic response. The radionuclide bone scan has been used as a visual indicator; however, there is some uncertainty as to its value in following changes in disease activity. Four patients with both serial technetium phosphate bone scans and serial gallium studies were studied. In each case the beneficial effect of calcitonin was demonstrated more accurately with gallium than with technetium diphosphonate. Since biochemical changes in Paget's disease are believed to be mediated at the cellular level and gallium uptake depends on cellular activity, it is proposed that gallium uptake is more appropriate measure of the activity of Paget's disease than a noncellular marker such as a technetium-containing bone scan agent.

  5. J/{psi} production in indium-indium collisions at SPS energies

    SciTech Connect

    Pillot, P.; Ducroux, L.; Guichard, A.; Tieulent, R.; Arnaldi, R.; Colla, A.; Cortese, P.; Ferretti, A.; Oppedisano, C.; Scomparin, E.; Averbeck, R.; Drees, A.; Banicz, K.; Keil, M.; Castor, J.; Devaux, A.; Force, P.; Manso, F.; Chaurand, B.; Cicalo, C.

    2006-01-12

    The NA60 experiment collected data on dimuon production in indium-indium collisions at 158 GeV/c per incident nucleon, in year 2003, to contribute to the clarification of several questions raised by previous experiments studying high-energy heavy-ion physics at the CERN SPS in search of the quark gluon plasma. Among these previous results stands the observation, by NA50, that the production yield of J/{psi} mesons is suppressed in central Pb-Pb collisions beyond the normal nuclear absorption defined by proton-nucleus data. By comparing the centrality dependence of the suppression pattern between different colliding systems, S-U, Pb-Pb and In-In, we should be able to identify the corresponding scaling variable, and the physics mechanism driving the suppression. In this paper, we will present the ratio of J/{psi} and Drell-Yan production cross-sections in indium-indium collisions, in three centrality bins, and how these values compare to previous measurements. We will also present a study of the transverse momentum distributions of the J/{psi} mesons, in seven centrality bins.

  6. Generator for ionic gallium-68 based on column chromatography

    DOEpatents

    Neirinckx, Rudi D.; Davis, Michael A.

    1981-01-01

    A physiologically acceptable solution of gallium-68 fluorides, having an activity of 0.1 to 50 millicuries per milliliter of solution is provided. The solution is obtained from a generator comprising germanium-68 hexafluoride bound to a column of an anion exchange resin which forms gallium-68 in situ by eluting the column with an acid solution to form a solution containing .sup.68 Ga-fluorides. The solution then is neutralized prior to administration.

  7. Complexometric determination of gallium with calcein blue as indicator

    USGS Publications Warehouse

    Elsheimer, H.N.

    1967-01-01

    A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1 % and a relative standard deviation of about 0.4% for 10 mg of gallium. ?? 1967.

  8. Detection of deep venous thrombophlebitis by gallium 67 scintigraphy

    SciTech Connect

    Miller, J.H.

    1981-07-01

    Deep venous thrombophlebitis may escape clinical detection. Three cases are reported in which whole-body gallium 67 scintigraphy was used to detect unsuspected deep venous thrombophlebitis related to indwelling catheters in three children who were being evaluated for fevers of unknown origin. Two of these children had septicemia from Candida organisms secondary to these venous lines. Gallium 67 scintigraphy may be useful in the detection of complications of indwelling venous catheters.

  9. Gallium-68 PSMA uptake in adrenal adenoma.

    PubMed

    Law, W Phillip; Fiumara, Frank; Fong, William; Miles, Kenneth A

    2016-08-01

    Gallium-68 (Ga-68) labelled prostate-specific membrane antigen (PSMA) imaging by positron emission tomography (PET) has emerged as a promising tool for staging of prostate cancer and restaging of disease in recurrence or biochemical failure after definitive treatment of prostate cancer. Ga-68 PSMA PET produces high target-to-background images of prostate cancer and its metastases which are reflective of the significant overexpression of PSMA in these cells and greatly facilitates tumour detection. However, relatively little is known about the PSMA expression of benign neoplasms and non-prostate epithelial malignancies. This is a case report of PSMA uptake in an adrenal adenoma incidentally discovered on PET performed for restaging of biochemically suspected prostate cancer recurrence. With the increasing use of PSMA PET in the management of prostate cancer - and the not infrequent occurrence of adrenal adenomas - the appearance of low- to moderate-grade PSMA uptake in adrenal adenomas should be one with which reporting clinicians are familiar.

  10. Contact formation in gallium arsenide solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1988-01-01

    Gold and gold-based alloys, commonly used as solar cell contact materials, are known to react readily with gallium arsenide. Experiments were performed to identify the mechanisms involved in these GaAs-metal interactions. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are explained by invoking this mechanism.

  11. Radiation damage of gallium arsenide production cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Garlick, G. F. J.

    1987-01-01

    High-efficiency gallium arsenide cells, made by the liquid epitaxy method (LPE), have been irradiated with 1-MeV electrons up to fluences of 10 to the 16th e/sq cm. Measurements have been made of cell spectral response and dark and light-excited current-voltage characteristics and analyzed using computer-based models to determine underlying parameters such as damage coefficients. It is possible to use spectral response to sort out damage effects in the different cell component layers. Damage coefficients are similar to other reported in the literature for the emitter and buffer (base). However, there is also a damage effect in the window layer and possibly at the window emitter interface similar to that found for proton-irradiated liquid-phase epitaxy-grown cells. Depletion layer recombination is found to be less than theoretically expected at high fluence.

  12. The interaction of gold with gallium arsenide

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1988-01-01

    Gold and gold-based alloys, commonly used as solar-cell contact materials, are known to react readily with gallium arsenide. Experiments designed to identify the mechanisms involved in these GaAs-metal interactions have yielded several interesting results. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are also explained by invoking this mechanism.

  13. Producing gallium arsenide crystals in space

    NASA Technical Reports Server (NTRS)

    Randolph, R. L.

    1984-01-01

    The production of high quality crystals in space is a promising near-term application of microgravity processing. Gallium arsenide is the selected material for initial commercial production because of its inherent superior electronic properties, wide range of market applications, and broad base of on-going device development effort. Plausible product prices can absorb the high cost of space transportation for the initial flights provided by the Space Transportation System. The next step for bulk crystal growth, beyond the STS, is planned to come later with the use of free flyers or a space station, where real benefits are foreseen. The use of these vehicles, together with refinement and increasing automation of space-based crystal growth factories, will bring down costs and will support growing demands for high quality GaAs and other specialty electronic and electro-optical crystals grown in space.

  14. Gallium Arsenide solar cell radiation damage experiment

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

    1991-01-01

    Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

  15. Optical properties of gadolinium gallium garnet.

    PubMed

    Wood, D L; Nassau, K

    1990-09-01

    The refractive index, the temperature coefficient of the refractive index, and the optical transparency of gadolinium gallium garnet are reported as a function of wavelength from the near UV to the middle IR. The materialis transparent enough for good optical components between 0.36 and 6.0 microm, and the refractive index ranges from 2.0 at the UV end to 1.8 at the IR end of the spectrum. The wavelength dependence of index is expressed as a three-term Sellmeier formula with agreement better than two parts in the fourth decimal between calculated and experimental values. Variations in composition depending on growth from various melts (e.g., stoichiometric vs congruent) have no effect on the optical parameters at this level of precision.

  16. Cavity optomechanics in gallium phosphide microdisks

    NASA Astrophysics Data System (ADS)

    Mitchell, Matthew; Hryciw, Aaron C.; Barclay, Paul E.

    2014-04-01

    We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8 × 105 and mode volumes <10(λ/n)3, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0 × 104 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 μm and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g0/2π˜30 kHz for the fundamental mechanical radial breathing mode at 488 MHz.

  17. Cathodoluminescence spectra of gallium nitride nanorods

    PubMed Central

    2011-01-01

    Gallium nitride [GaN] nanorods grown on a Si(111) substrate at 720°C via plasma-assisted molecular beam epitaxy were studied by field-emission electron microscopy and cathodoluminescence [CL]. The surface topography and optical properties of the GaN nanorod cluster and single GaN nanorod were measured and discussed. The defect-related CL spectra of GaN nanorods and their dependence on temperature were investigated. The CL spectra along the length of the individual GaN nanorod were also studied. The results reveal that the 3.2-eV peak comes from the structural defect at the interface between the GaN nanorod and Si substrate. The surface state emission of the single GaN nanorod is stronger as the diameter of the GaN nanorod becomes smaller due to an increased surface-to-volume ratio. PMID:22168896

  18. Direct band gap wurtzite gallium phosphide nanowires.

    PubMed

    Assali, S; Zardo, I; Plissard, S; Kriegner, D; Verheijen, M A; Bauer, G; Meijerink, A; Belabbes, A; Bechstedt, F; Haverkort, J E M; Bakkers, E P A M

    2013-04-10

    The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality.

  19. Gallium arsenide solar array subsystem study

    NASA Technical Reports Server (NTRS)

    Miller, F. Q.

    1982-01-01

    The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

  20. Cavity optomechanics in gallium phosphide microdisks

    SciTech Connect

    Mitchell, Matthew; Barclay, Paul E.; Hryciw, Aaron C.

    2014-04-07

    We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors >2.8 × 10{sup 5} and mode volumes <10(λ/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 μm and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g{sub 0}/2π∼30 kHz for the fundamental mechanical radial breathing mode at 488 MHz.