WorldWideScience

Sample records for antimonides

  1. Growth and characterization of indium antimonide and gallium antimonide crystals

    Indian Academy of Sciences (India)

    N K Udayashankar; H L Bhat

    2001-10-01

    Indium antimonide and gallium antimonide were synthesized from the respective component elements using an indigenously fabricated synthesis unit. Bulk crystals of indium antimonide and gallium antimonide were grown using both the vertical and horizontal Bridgman techniques. Effect of ampoule shapes and diameters on the crystallinity and homogeneity was studied. The grown crystals were characterized using X-ray analysis, EDAX, chemical etching, Hall effect and conductivity measurements. In the case of gallium antimonide, effect of dopants (Te and In) on transport and photoluminescence properties was investigated.

  2. Antimonide-based interdiffused quantum wells

    OpenAIRE

    Sim, SKH; Li, EH; Mutamba, K.; Hartnagel, HL

    1998-01-01

    Antimonide (Sb) is said to be an emerging optoelectronic materials for both high speed and long wavelength electronics devices. Recently, there has been much research activities on antimonide based system. Among Group V elements, antimonide is of particular interest as its lattice parameter matches solid solutions of various ternary and quaternary III-V compounds whose band gap cover a wide spectral range from absorption in antimonide based superlattices, detection of longer wavelength of 8 t...

  3. Temperature Dependent Ultrasonic Study in Scandium Antimonide Semiconductor

    OpenAIRE

    Gupta, A.K.; Srivastava, S.; Thapa, K. B.

    2012-01-01

    In this paper analysis of wave propagation of elastic wave in scandium antimonide semiconductor was investigated. In scandium antimonide semiconductor, NaCl structure was found. Ultrasonic properties like ultrasonic attenuation, sound velocities, acoustic coupling constants, and thermal relaxation time have been investigated in cubic scandium antimonide semiconductor. Second and third order elastic constant have been computed for the evaluation of above said ultrasonic properties. Second and ...

  4. Indium Antimonide Nanowires: Synthesis, Characterization, and Applications

    OpenAIRE

    Penchev, Miroslav Valentinov

    2012-01-01

    Indium Antimonide (InSb) nanowires with a diameter ranging from 30 nm to 200 nm, were synthesized by electrochemical disposition in anodized alumina and polycarbonate porous membranes. In addition, epitaxial single crystalline InSb nanowires with diameters ranging from 5 nm to 100 nm, were synthesized by chemical vapor deposition (CVD) using Au nanoparticles as catalyst. Structural and material characterization of InSb nanowires was carried out by scanning electron microscopy (SEM), energy di...

  5. Indium Antimonide Nanowires: Synthesis and Properties.

    Science.gov (United States)

    Shafa, Muhammad; Akbar, Sadaf; Gao, Lei; Fakhar-E-Alam, Muhammad; Wang, Zhiming M

    2016-12-01

    This article summarizes some of the critical features of pure indium antimonide nanowires (InSb NWs) growth and their potential applications in the industry. In the first section, historical studies on the growth of InSb NWs have been presented, while in the second part, a comprehensive overview of the various synthesis techniques is demonstrated briefly. The major emphasis of current review is vapor phase deposition of NWs by manifold techniques. In addition, author review various protocols and methodologies employed to generate NWs from diverse material systems via self-organized fabrication procedures comprising chemical vapor deposition, annealing in reactive atmosphere, evaporation of InSb, molecular/ chemical beam epitaxy, solution-based techniques, and top-down fabrication method. The benefits and ill effects of the gold and self-catalyzed materials for the growth of NWs are explained at length. Afterward, in the next part, four thermodynamic characteristics of NW growth criterion concerning the expansion of NWs, growth velocity, Gibbs-Thomson effect, and growth model were expounded and discussed concisely. Recent progress in device fabrications is explained in the third part, in which the electrical and optical properties of InSb NWs were reviewed by considering the effects of conductivity which are diameter dependent and the applications of NWs in the fabrications of field-effect transistors, quantum devices, thermoelectrics, and detectors. PMID:27009531

  6. Indium Antimonide Nanowires: Synthesis and Properties

    Science.gov (United States)

    Shafa, Muhammad; Akbar, Sadaf; Gao, Lei; Fakhar-e-Alam, Muhammad; Wang, Zhiming M.

    2016-03-01

    This article summarizes some of the critical features of pure indium antimonide nanowires (InSb NWs) growth and their potential applications in the industry. In the first section, historical studies on the growth of InSb NWs have been presented, while in the second part, a comprehensive overview of the various synthesis techniques is demonstrated briefly. The major emphasis of current review is vapor phase deposition of NWs by manifold techniques. In addition, author review various protocols and methodologies employed to generate NWs from diverse material systems via self-organized fabrication procedures comprising chemical vapor deposition, annealing in reactive atmosphere, evaporation of InSb, molecular/ chemical beam epitaxy, solution-based techniques, and top-down fabrication method. The benefits and ill effects of the gold and self-catalyzed materials for the growth of NWs are explained at length. Afterward, in the next part, four thermodynamic characteristics of NW growth criterion concerning the expansion of NWs, growth velocity, Gibbs-Thomson effect, and growth model were expounded and discussed concisely. Recent progress in device fabrications is explained in the third part, in which the electrical and optical properties of InSb NWs were reviewed by considering the effects of conductivity which are diameter dependent and the applications of NWs in the fabrications of field-effect transistors, quantum devices, thermoelectrics, and detectors.

  7. Self- and zinc diffusion in gallium antimonide

    International Nuclear Information System (INIS)

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

  8. Research on structure and electrical parameters of indium antimonide films

    International Nuclear Information System (INIS)

    Results of investigations into the effect of conditions of formation of indium antimonide films prepared by thermal vacuum spraying on their structure, phase composition and electric parameters, are presented. The method of studying the synthesized semiconductor layers on the DRON-0.5 X-ray device with CoKsub(α)-radiation is tested. The dependence of structure, phase composition and electric properties of InSb layers 1+3 μm thick sprayed on ferrite substrates on condensation temperature, is established. Hexagonal InSb modification is found

  9. Reactive ion beam etching of aluminum indium antimonide, gallium indium antimonide heterostructures in electron cyclotron resonance methane/hydrogen/nitrogen/silicon tetrachloride discharges at room temperature

    OpenAIRE

    Sendra, J. R.; Anguita, José Virgilio; Pérez Camacho, J. J.; Briones Fernández-Pola, Fernando

    1995-01-01

    Reactive ion beam etching of aluminum indium antimonide, gallium indium antimonide heterostructures in electron cyclotron resonance plasma using methane/hydrogen/nitrogen/silicon tetrachloride (CH4/H2/N2/SiCl4) mixtures has been performed at room temperature. Due to the ratio of chlorine to methane, formation of an indium chloride layer on the etched surface is avoided, thus resulting, in etched surfaces as smooth as the original ones and flat mesa sidewalls. Infrared diodes (2.3µm) have been...

  10. Study on actinoid isolation by antimonide ion exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Masamichi [Tokyo Inst. of Tech. (Japan). Faculty of Science; Kubota, Masumitsu; Yamagishi, Isao

    1996-01-01

    To establish a containment of long-life nuclides and an effective reduction of waste volume is important to reduce the loadings on the natural environment. Chemical isolation of radioactive nuclides from wastes was attempted by using inorganic ion exchanger with high specificity and thermal stability. In this study, titanium antimonide was used as an ion exchanger to investigate the adsorption of trivalent metallic ions according to Kielland plot curves. When the ionic equivalent fraction (X-bar{sub M}) was around 0.005, Kielland plot curve of either of 3-valent metallic ions was bent, suggesting the exchanger had two different adsorption sites. The slope of the curve became smaller as an elevation of temperature. These results show that the ion radius was decreased resulting from partial elimination of the hydrated water of ion and thus, the steric conditions around the exchange site might be improved. (M.N.)

  11. High pressure behaviour of heavy rare earth mono antimonides

    International Nuclear Information System (INIS)

    We have investigated theoretically the high-pressure structural phase transition and cohesive properties of two heavy rare earth mono antimonides (RESb; RE = Dy and Lu) by using two body interionic potential with necessary modifications to include the effect of Coulomb screening by the delocalized 4f electrons of the RE ion. The peculiar properties of these compounds have been interpreted in terms of the hybridization of f electrons with the conduction band and strong mixing of f states of RE ion with the p orbital of neighboring pnictogen ion. These compounds exhibit first order crystallographic phase transition from their NaCl (B1) phase to CsCl (B2) phase at 23.6 GPa and 25.4 GPa respectively. The bulk modulii of RESb compounds are obtained from the P-V curve fitted by the Birch equation of state. We also calculated the RE-RE distance as a function of pressure. Elastic properties of these compounds have also been studied and their second order elastic constants are calculated.

  12. Room temperature aluminum antimonide radiation detector and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    Lordi, Vincenzo; Wu, Kuang Jen J.; Aberg, Daniel; Erhart, Paul; Coombs, III, Arthur W; Sturm, Benjamin W

    2015-03-03

    In one embodiment, a method for producing a high-purity single crystal of aluminum antimonide (AlSb) includes providing a growing environment with which to grow a crystal, growing a single crystal of AlSb in the growing environment which comprises hydrogen (H.sub.2) gas to reduce oxide formation and subsequent incorporation of oxygen impurities in the crystal, and adding a controlled amount of at least one impurity to the growing environment to effectively incorporate at least one dopant into the crystal. In another embodiment, a high energy radiation detector includes a single high-purity crystal of AlSb, a supporting structure for the crystal, and logic for interpreting signals obtained from the crystal which is operable as a radiation detector at a temperature of about 25.degree. C. In one embodiment, a high-purity single crystal of AlSb includes AlSb and at least one dopant selected from a group consisting of selenium (Se), tellurium (Te), and tin (Sn).

  13. Sensor of hydrostatic pressure based on gallium antimonide microcrystals

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2015-08-01

    Full Text Available Currently, silicon and germanium, the most common materials in the production of discrete semiconductor devices and integrated circuits, do not always meet all the requirements to the sensing elements of mechanical quantities sensors. Therefore, it is logical to research the properties of other semiconductor materials that could be used as sensing elements in such sensors. A3B5 semiconductor compounds seem promising for such purpose. Effect of hydrostatic pressure up to 5000 bar on the resistance of n-type antimonide gallium whiskers doped by Se or Te was studied. Coefficient of hydrostatic pressure for this crystals was determined, it equals Kh = (16,5—20,0•10–5 bar–1 at 20°N. Temperature dependence of resistance and coefficient Kh for this crystals in the temperature range ±60°N was studied. Design of the developed hydrostatic pressure sensor based on GaSb whiskers and its characteristics are presented. The possibility to decrease the temperature dependence of sensitive element resistance by mounting GaSb whiskers on the substrates fabricated from materials with different temperature coefficient of expansion was examined. It was shown that mounting of GaSb crystals on Cu substrate gives the optimal result, in this case the temperature coefficient decrease to 0,05%•°N–1, that leads to decrease of output temperature dependence. The main advantages of developed pressure sensor are: the simplified design in comparison with pressure sensors with strain gauges mounted on spring elements; the high sensitivity to pressure that is constant in the wide pressure range; the improvement of sensors metrological characteristics owing to hysteresis absence. The possible application fields of developed sensors are measuring of high and extremely high pressure, chemical and oil industries, measuring of pressure in oil bore-holes, investigation of explosive processes.

  14. Indium antimonide nanowires arrays for promising thermoelectric converters

    Directory of Open Access Journals (Sweden)

    Gorokh G. G.

    2015-02-01

    Full Text Available The authors have theoretically substantiated the possibility to create promising thermoelectric converters based on quantum wires. The calculations have shown that the use of quantum wires with lateral dimensions smaller than quantum confinement values and high concentration and mobility of electrons, can lead to a substantial cooling of one of the contacts up to tens of degrees and to the heating of the other. The technological methods of manufacturing of indium antimonide nanowires arrays with high aspect ratio of the nanowire diameters to their length in the modified nanoporous anodic alumina matrixes were developed and tested. The microstructure and composition of the formed nanostructures were investigated. The electron microscopy allowed establishing that within each pore nanowires are formed with diameters of 35 nm and a length of 35 microns (equal to the matrix thickness. The electron probe x-ray microanalysis has shown that the atomic ratio of indium and antimony in the semiconductor nanostructures amounted to 38,26% and 61,74%, respectively. The current-voltage measurement between the upper and lower contacts of Cu/InSb/Cu structure (1 mm2 has shown that at 2.82 V negative voltage at the emitter contact, current density is 129,8 A/cм2, and the collector contact is heated up to 75 degrees during 150 sec. Thus, the experimental results confirmed the theoretical findings that the quantum wire systems can be used to create thermoelectric devices, which can be widely applied in electronics, in particular, for cooling integrated circuits (processors, thermal controlling of the electrical circuits by changing voltage value.

  15. Determination of tellurium in indium antimonide semiconductor material by electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Shiue, M Y; Sun, Y C; Yang, M H

    2001-08-01

    A method for the determination of the dopant concentration of tellurium in dissolved indium antimonide semiconductor material by electrothermal atomic absorption spectrometry (ETAAS) was developed. Efforts were made to investigate the optimal conditions of the furnace heating program and the effect of palladium modifier on the variation of tellurium and the background absorbance. According to the results obtained, the presence of palladium chemical modifier in the analysis of indium antimonide allowed the successful retention of tellurium in the graphite tube, and the optimum mass of palladium modifier was found to be dependent on the sample matrix concentration. The absorbance profile of tellurium and the background level were significantly improved when a pyrolysis temperature of 1100 degrees C and an atomization temperature of 2200 degrees C were employed in the optimized heating program. With the use of this method, a detection limit of 0.8 microg g(-1) tellurium in indium antimonide could be achieved. The applicability of the proposed method was evaluated by comparison with two independent methods, i.e. slurry sampling-ETAAS and ICP-MS. From the good agreement between the results, it was demonstrated that the proposed method is suitable for the determination of typical dopant concentrations of tellurium in indium antimonide. PMID:11534624

  16. Low Cost High Performance Zinc Antimonide Thin Films for Thermoelectric Applications

    DEFF Research Database (Denmark)

    Sun, Ye; Christensen, Mogens; Johnsen, Simon;

    2012-01-01

    Zinc antimonide thin films with high thermoelectric performance are produced by a simple sputtering method. The phase-pure Zn4Sb3 and ZnSb thin films fulfill the key requirements for commercial TE power generation: cheap elements, cheap fabrication method, high performance and thermal stability. In...

  17. Spontaneous atomic ordering in MOVPE grown gallium arsenide antimonide

    Science.gov (United States)

    Jiang, Weiyang

    process. It is unlikely that the ordering mechanism is similar to the dimer-induced strain models that have been successfully used to explain CuPt ordering in InGaP. We propose a simple model based on alternating incorporation of group V adatoms at step edges. Keywords. GaAsSb; MOVPE; Bi surfactant; TEM; CuAu ordering. Subject. Gallium Arsenide Antimonide; Metalorganic Vapor-phase Epitaxy; Bismuth Surfactant; Transmission Electron Microscopy; CuAu Ordering.

  18. Combustion synthesis: A new approach for preparation of thermoelectric zinc antimonide compounds

    International Nuclear Information System (INIS)

    Highlights: ► Reliable preparation method of thermoelectric materials. ► Formation of zinc antimonide by the combustion synthesis method is investigated. ► XRD and Raman spectroscopy as a function of temperature. ► SHS: a new way for synthesizing thermoelectric materials. - Abstract: Due to the interesting properties of Zn4Sb3 thermoelectric material, a reliable preparation method of this material is required. In this study, the formation of zinc antimonides by the combustion synthesis method is investigated and subjected to characterization using X-ray diffraction and Raman spectroscopy as a function of temperature. The results show that combustion synthesis can be a new way for synthesizing these thermoelectric materials.

  19. Synthesis, Structure and Properties of Scandium Dysprosium Antimonide, ScDySb

    OpenAIRE

    Nuss, Jürgen; Wedig, Ulrich; Jansen, Martin

    2010-01-01

    Abstract Scandium dysprosium antimonide ScDySb was synthesized from scandium metal and DySb in an all-solid state reaction at 1770 K. According to X-ray analysis of the crystal structure (P4/nmm, Z = 4, a = 430.78(1) pm, c = 816.43(4) pm, R1 = 0.0238, wR(all) = 0.0688, 268 independent reflections), ScDySb adopts the anti-PbFCl type of structure, but with pronounced deviations in structural details, which are related to specific bonding interactions between the atoms involved. ScDyS...

  20. X-ray Photoemission Spectroscopy Studies of Cesium Antimonide Photocathodes for Photoinjector Applications

    Science.gov (United States)

    Martini, Irene; Chevallay, Eric; Fedosseev, Valentin; Hessler, Christoph; Neupert, Holger; Nistor, Valentin; Taborelli, Mauro

    Within the CLIC (Compact Linear Collider) project, feasibility studies of a photoinjector option for the drive beam as an alternative to its baseline design using a thermionic electron gun (Geschonke et al. [1]) are on-going. This R&D program covers both the laser and the photocathode side. Cesium antimonide cathodes were produced at CERN by co-deposition onto copper substrates and characterized by photoemission and by XPS (X-ray Photoemission Spectroscopy) analysis. A systematic study on newly produced and used photocathodes was conducted in order to correlate the surface composition to the photoemissive properties.

  1. Photoemission from Graphene on Copper and Cesium Antimonide: Theory and Experiment

    Science.gov (United States)

    Finkenstadt, Daniel; Jensen, Kevin L.; Lambrakos, Samuel G.; Shabaev, Andrew; Moody, Nathan A.

    The work function is calculated using DFT for a substrate of flat copper on which a single layer of graphene is deposited. These calculations show a reduced work function, compared to bare copper, when graphene is deposited on a cathode. Based on our DFT-calculated results, a simple model using the transfer matrix approach gives the transmission probability near and above the barrier maximum. An important element of our model is the DFT-calculated, macroscopically-averaged electrostatic potential. Using this potential, graphene behaves as a resonant well for electrons transmitted between the substrate and vacuum regions. Another system to be discussed is graphene atop cesium antimonide, which has very low work function making it technologically useful, in particular for the development of an x-ray free electron laser. On cesium antimonide, we examine whether graphene may allow for the retention of an underlying cesium layer that is often damaged in high-field applications. A discussion of these results in light of recent experimental characterization at LANL will be given. Funding and support provide by ONR and DOE.

  2. The effect of an excess of components on the electrical properties of indium-antimonide films

    International Nuclear Information System (INIS)

    The causes of anomalous behavior of the Hall mobility of charge carriers as a result of a decrease in the measurement temperature from 300 K in indium-antimonide films obtained by the method of three temperatures are studied. It is shown experimentally that there exist drops in the “admissible” temperatures of evaporators of components and the substrate within which continuous conducting films are obtained. The optimal conditions for sample preparation for which the values of the mobility remain practically constant in the temperature range of 150–350 K are determined. On the basis of the comparison with optical-transmission spectra, it is concluded that there is a high concentration of defects in the films; these defects are related to deviation of the composition from stoichiometry and act as donor and acceptor centers. The presence of such defects makes it possible to explain the decrease in mobility in the films as the temperature is lowered

  3. Experimental Investigation of Zinc Antimonide Thin Films under Different Thermal Boundary Conditions

    DEFF Research Database (Denmark)

    Mir Hosseini, Seyed Mojtaba; Rosendahl, Lasse Aistrup; Rezaniakolaei, Alireza

    Zinc antimonide compound ZnxSby is one of the most efficient thermoelectric (TE) materials known at high temperatures regarding to its exceptional low thermal conductivity. For this reason, it continues to be the focus of active research. However, before practical use in actual conditions, it is...... imperative to analyze the thermo electrical behavior of these materials. In this study, the results are considered for different hot side temperature of the film in steady state condition. Six temperatures at hot side of the specimen are provided; 150, 200, 250, 300, 350, and 400 ᵒC. At the beginning of each...... is able to operate in relatively high range of temperature with long working period without failure. Furthermore, effects of implementing thermal cycling on stability analysis of a TEG sample are considered. By testing the thermoelectric thin film specimen during a thermal cycling, behavior of the...

  4. Gallium antimonide texturing for enhanced light extraction from infrared optoelectronics devices

    Directory of Open Access Journals (Sweden)

    Ella Wassweiler

    2016-06-01

    Full Text Available The use of gallium antimonide (GaSb is increasing, especially for optoelectronic devices in the infrared wavelengths. It has been demonstrated in gallium nitride (GaN devices operating at ultraviolet (UV wavelengths, that surface textures increase the overall device efficiency. In this work, we fabricated eight different surface textures in GaSb to be used in enhancing efficiency in infrared wavelength devices. Through chemical etching with hydrofluoric acid, hydrogen peroxide, and tartaric acid we characterize the types of surface textures formed and the removal rate of entire layers of GaSb. Through optimization of the etching recipes we lower the reflectivity from 35.7% to 1% at 4 μm wavelength for bare and textured GaSb, respectively. In addition, we simulate surface textures using ray optics in finite element method solver software to provide explanation of our experimental findings.

  5. Carrier dynamics in highly quantum-confined, colloidal indium antimonide nanocrystals.

    Science.gov (United States)

    Chang, Angela Y; Liu, Wenyong; Talapin, Dmitri V; Schaller, Richard D

    2014-08-26

    Nanometer-sized particles of indium antimonide (InSb) offer opportunities in areas such as solar energy conversion and single photon sources. Here, we measure electron-hole pair dynamics, spectra, and absorption cross sections of strongly quantum-confined colloidal InSb nanocrystal quantum dots using femtosecond transient absorption. For all samples, we observe a bleach feature that develops on ultrafast time scales, which notably moves to lower energy during the first several picoseconds following excitation. We associate this unusual red shift, which becomes larger for larger particles and more distinct at lower sample temperatures, with hot exciton cooling through states that we suggest arise from energetically proximal conduction band levels. From controlled optical excitation intensities, we determine biexciton lifetimes, which range from 2 to 20 ps for the studied 3-6 nm diameter particle sizes. PMID:25106893

  6. Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

    International Nuclear Information System (INIS)

    Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency

  7. Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

    Science.gov (United States)

    Ruiz-Osés, M.; Schubert, S.; Attenkofer, K.; Ben-Zvi, I.; Liang, X.; Muller, E.; Padmore, H.; Rao, T.; Vecchione, T.; Wong, J.; Xie, J.; Smedley, J.

    2014-12-01

    Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.

  8. Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Osés, M.; Ben-Zvi, I.; Liang, X.; Muller, E. [Stony Brook University, Stony Brook, New York 11794 (United States); Schubert, S. [Helmholtz-Zentrum Berlin, Albert-Einstein Str. 15, 12489 Berlin (Germany); Brookhaven National Laboratory, Upton, New York 11973 (United States); Attenkofer, K.; Rao, T.; Smedley, J., E-mail: smedley@bnl.gov [Brookhaven National Laboratory, Upton, New York 11973 (United States); Padmore, H.; Vecchione, T.; Wong, J. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Xie, J. [Argonne National Laboratory, Lemont, Illinois 60439 (United States)

    2014-12-01

    Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K{sub 2}CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K{sub 2}CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.

  9. Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

    Directory of Open Access Journals (Sweden)

    M. Ruiz-Osés

    2014-12-01

    Full Text Available Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100 substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.

  10. Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

    OpenAIRE

    M. Ruiz-Osés; Schubert, S.; Attenkofer, K.; Ben-Zvi, I.; Liang, X; Muller, E; Padmore, H; Rao, T.; T. Vecchione; Wong, J; Xie, J.; Smedley, J.

    2014-01-01

    Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolv...

  11. Thermal Cycling Behavior of Zinc Antimonide Thin Films for High Temperature Thermoelectric Power Generation Applications.

    Science.gov (United States)

    Shim, Hyung Cheoul; Woo, Chang-Su; Han, Seungwoo

    2015-08-19

    The zinc antimonide compound ZnxSby is one of the most efficient thermoelectric materials known at high temperatures due to its exceptional low thermal conductivity. For this reason, it continues to be the focus of active research, especially regarding its glass-like atomic structure. However, before practical use in actual surroundings, such as near a vehicle manifold, it is imperative to analyze the thermal reliability of these materials. Herein, we present the thermal cycling behavior of ZnxSby thin films in nitrogen (N2) purged or ambient atmosphere. ZnxSby thin films were prepared by cosputtering and reached a power factor of 1.39 mW m(-1) K(-2) at 321 °C. We found maximum power factor values gradually decreased in N2 atmosphere due to increasing resistivity with repeated cycling, whereas the specimen in air kept its performance. X-ray diffraction and electron microscopy observations revealed that fluidity of Zn atoms leads to nanoprecipitates, porous morphologies, and even growth of a coating layer or fiber structures on the surface of ZnxSby after repetitive heating and cooling cycles. With this in mind, our results indicate that proper encapsulation of the ZnxSby surface would reduce these unwanted side reactions and the resulting degradation of thermoelectric performance. PMID:26226167

  12. Elusive β-Zn8Sb7: A New Zinc Antimonide Thermoelectric.

    Science.gov (United States)

    Wang, Jian; Kovnir, Kirill

    2015-10-01

    Zn8Sb7 was theoretically predicted to exhibit superior thermoelectric properties; however a crystalline phase with a similar composition was only stabilized in the form of nanoparticles. We report a new metastable compound, β-Zn8Sb7, which was synthesized in the form of bulk polycrystalline powder via high-temperature solid-state annealing followed by quenching. Single crystal X-ray diffraction indicates that β-Zn8Sb7 crystallizes in a new structure type (noncentrosymmetric orthorhombic space group Pmn21 (no. 31) with unit cell parameters of a = 15.029(1) Å, b = 7.7310(5) Å, c = 12.7431(9) Å, which is different from the nanoparticulate phase. According to differential scanning calorimetry, the β-Zn8Sb7 phase melts incongruently at 825(5) K. β-Zn8Sb7 is a p-type semiconductor with high Seebeck thermopower and low thermal conductivity stemming from the complex crystal structure. β-Zn8Sb7 exhibits a promising thermoelectric figure-of-merit, zT, of 0.33 at 400 K, which is comparable to the state-of-the-art thermoelectric materials based on binary zinc antimonides. PMID:26372068

  13. Time-resolved X-ray diffraction at monocrystalline indium antimonide

    International Nuclear Information System (INIS)

    The present work deals with the experimental study of the structural change of the semiconductor indium antimonide (InSb) after excitation by an ultrashort laser pulse (60 fs). The investigation is carried out by ultra-short X-ray pulses (around 100 fs). As a source for ultrashort X-ray pulses serves a laser plasma X-ray source. With this source, a more intense ultrashort optical laser pulse is focused onto a metal foil (intensity to 8.1016 W/cm2), and by the resulting plasma, there is an emission of X-rays. To characterize the X-ray source a novel Timepix detector was used, which made it possible to detect Bremsstrahlung up to photon energies of 700 keV. The penetration depth of X-rays is usually several micrometers and is thus much greater than the penetration depth of 100 nm of the laser pulse used for excitation. By the use of a highly asymmetric Bragg reflex the penetration depth of X-rays could be adapted to the penetration depth of the excitation pulse. Due to the low penetration depth of 2 ps after excitation an expansion of 4% of a 4 nm thin layer at the surface can already be measured. The excitation of the semiconductor will be described with different models theoretically, the temporal evolution of the deformation obtained therefrom is compared with the performed measurements.

  14. Indium-bump-free antimonide superlattice membrane detectors on silicon substrates

    Science.gov (United States)

    Zamiri, M.; Klein, B.; Schuler-Sandy, T.; Myers, S.; Dahiya, V.; Cavallo, F.; Krishna, S.

    2016-02-01

    We present an approach to realize antimonide superlattices on silicon substrates without using conventional Indium-bump hybridization. In this approach, PIN superlattices are grown on top of a 60 nm Al0.6Ga0.4Sb sacrificial layer on a GaSb host substrate. Following the growth, the individual pixels are transferred using our epitaxial-lift off technique, which consists of a wet-etch to undercut the pixels followed by a dry-stamp process to transfer the pixels to a silicon substrate prepared with a gold layer. Structural and optical characterization of the transferred pixels was done using an optical microscope, scanning electron microscopy, and photoluminescence. The interface between the transferred pixels and the new substrate was abrupt, and no significant degradation in the optical quality was observed. An Indium-bump-free membrane detector was then fabricated using this approach. Spectral response measurements provided a 100% cut-off wavelength of 4.3 μm at 77 K. The performance of the membrane detector was compared to a control detector on the as-grown substrate. The membrane detector was limited by surface leakage current. The proposed approach could pave the way for wafer-level integration of photonic detectors on silicon substrates, which could dramatically reduce the cost of these detectors.

  15. Constitutional properties of rare earth antimonides: trends and optimization Sm-Sb and Er-Sb alloys

    International Nuclear Information System (INIS)

    General, constitutional properties of the rare earth antimonides are briefly summarized. The trends observed in the crystallochemistry, thermodynamics and phase diagrams of these substances are discussed and used as an evaluation criterion for the reliability of the different specific data and for defining typical assessment procedures. Some results recently obtained in the thermochemical investigation of binary Er-Sb alloys are presented. The Sm-Sb system is then especially considered and assessed. By using the Lukas program a thermodynamic optimization of this system is carried out. (orig.)

  16. Synthesis and characterisation of (poly-)antimonides and N-doped ZnO

    International Nuclear Information System (INIS)

    This thesis focused on the investigation of novel and known materials in the binary system TxSby (T = transition metal) and in the ternary system MxTySbz (M = Hf, Zr). The compounds were tested as anode materials for lithium-ion-batteries. In addition, the electronic conductivity and the magnetic behavior at low temperatures were tested. Main focus of this work was on the bonding situation in the antimony networks. To compare the results of the characterization of known or novel metallic/covalent compounds, all materials were synthesized and characterized either by solid state synthesis in a muffle furnace or by arc melting. In the ternary system MxTySbz (M = Hf, Zr; T = Cu, Ni, Pd), all compounds show covalent as well as metallic bonding character. Phase pure Zr3TSb7 (T = Ni, Pd) and Zr2TSb3 (T = Cu, Pd), were tested as potential anode materials for lithium-ion batteries. During electrochemical cycling these ternary compounds invariably convert to Li3Sb and the respective transition metals. Magnetic measurements of these materials show typical behaviour of intermetallic compounds. In a ZFC-FC-measurement of Zr3NiSb7 a superconductive phase with 2 vol% superconducting material at Tc = 10.9 K could be detected. The low volume superconductivity indicates that a side phase is responsible for this behaviour. Ternary Hf10NiSb18, Zr5NiSb9 and Zr4CuSb7 were also synthesized by systematic variation of the synthesis conditions. The crystal structures were solved and showed a similar structure to the Hf5Sb9 structure type. In the case of Zr4CuSb9, phase purity was detected by Xray powder diffraction and the physical properties were measured. Due to ex-situ X-ray powder diffraction it was shown that the compound is disintegrating during lithiation and is re-formed during delithiation up to the 20th cycle. MxSby (M = Hf, Zr) as representatives of binary antimonides were synthesized. Through Fe and/or Ni doping superconducting Phases have been found. Furthermore binary chromium-antimonides

  17. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    International Nuclear Information System (INIS)

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0〉 orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 1017 cm−3 were irradiated at 100 MeV Fe7+ ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 1010–1 × 1014 ions cm−2. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 1013, 5 × 1013 and 1 × 1014 ions cm−2, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 1013 ion cm−2 was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E1, E1 + Δ and E2 band gaps in all irradiated samples

  18. Zn(5)Sb(4)In(2-delta) - a ternary derivative of thermoelectric zinc antimonides.

    Science.gov (United States)

    Wu, Yang; Lidin, Sven; Groy, Thomas L; Newman, N; Häussermann, Ulrich

    2009-07-01

    Zn(5)Sb(4)In(2-delta) (delta = 0.15(3)) was synthesized in the form of millimeter-sized crystals from reaction mixtures containing excess zinc. The ternary intermetallic compound is temperature polymorphic, and at room temperature it crystallizes with a new structure type in the orthorhombic space group Pbcn, where a = 7.1619(2), b = 17.1562(4), c = 8.6887(4) A, V = 1067.6(1) A(3), and Z = 4. The structure features 3(2)434 nets of Sb atoms that are stacked in antiposition to yield layers of square antiprisms sharing edges plus intervening tetracapped tetrahedra (tetreadersterns). The majority of Zn atoms occupy peripheral tetrahedra of such tetraedersterns, and attain at the same time the peculiar five-coordination by one like atom and four Sb atoms typical for the structures of binary zinc antimonides. The In and remaining Zn atoms are distributed in the tetragonal channels formed by the square antiprisms and display some disorder. At temperatures below 200 K Zn(5)Sb(4)In(2-delta) undergoes a phase transition into a more ordered structure with monoclinic symmetry (P2(1)/c) without any change of the unit cell. The thermoelectric properties of Zn(5)Sb(4)In(2-delta) were measured between 10 and 350 K. Exceptionally low thermal conductivity values (1 W/mK range) were obtained in the whole temperature range. Resistivity and thermopower values are characteristic of a heavily doped or degenerate semiconductor (2.5 mOmega cm and 160 muV/K, respectively, at room temperature) and show a discontinuity around 220 K. The thermoelectric figure of merit of Zn(5)Sb(4)In(2-delta) is higher than that of Zn(4)Sb(3) in the investigated temperature range. PMID:19476316

  19. Lanthanum Gallium Tin Antimonides LaGa xSn ySb 2

    Science.gov (United States)

    Morgan, Mark G.; Wang, Meitian; Mills, Allison M.; Mar, Arthur

    2002-08-01

    A series of quaternary lanthanum gallium tin antimonides LaGa xSn ySb 2 was elaborated to trace the structural evolution between the known end members LaGaSb 2 (SmGaSb 2-type) and LaSn ySb 2 (LaSn 0.75Sb 2-type). Five members of this series were characterized by single-crystal X-ray diffraction. For low Sn content, the Sn atoms disorder with Ga atoms in zigzag chains to form solid solutions LaGa 1- ySn ySb 2 (0≤y≤0.2) adopting the SmGaSb 2-type structure, as exemplified by LaGa 0.92(3)Sn 0.08Sb 2 and LaGa 0.80(3)Sn 0.20Sb 2 (orthorhombic, space group D52- C222 1, Z=4). For higher Sn and lower Ga content, there is a segregation in which the Sn atoms appear in chains of closely spaced partially occupied sites as in the parent LaSn 0.75Sb 2-type structure whereas the Ga atoms remain in zigzag chains as in the parent SmGaSb 2-type structure. This feature is observed in the structures of LaGa 0.68(4)Sn 0.31(3)Sb 2, LaGa 0.62(3)Sn 0.32(3)Sb 2, and LaGa 0.43(3)Sn 0.39(3)Sb 2 (orthorhombic, space group D172 h- Cmcm, Z=4). The last example illustrates that the combined Ga/Sn content can be substoichiometric ( x+ y<1). These compounds have a layered nature, with the chains of Ga or Sn atoms residing between 2∞[LaSb 2] slabs.

  20. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Vidya, E-mail: vj1510@yahoo.com

    2015-09-01

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0〉 orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 10{sup 17} cm{sup −3} were irradiated at 100 MeV Fe{sup 7+} ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 10{sup 10}–1 × 10{sup 14} ions cm{sup −2}. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 10{sup 13}, 5 × 10{sup 13} and 1 × 10{sup 14} ions cm{sup −2}, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 10{sup 13} ion cm{sup −2} was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E{sub 1}, E{sub 1} + Δ and E{sub 2} band gaps in all irradiated samples.

  1. Inclusion of electronic polarizability effect in high pressure structural properties of alloy of rare-earth antimonides

    International Nuclear Information System (INIS)

    In the present paper, we have investigated the high-pressure structural phase transition of rare-earth antimonides (NdSb and DySb). We studied theoretically the structural properties of alloy of these compounds (NdSb and DySb) by using the three-body potential model with the effect of electronic polarizability (TBIPEP). These compounds exhibit first order crystallographic phase transition from NaCl (B1) to CsCl (B2) phase at 17.8 GPa and 22.6 GPa respectively. The study has been extended to mixed crystals and the effect of composition on transition pressure and volume change is investigated. The phase transition pressures and associated volume collapse obtained from present potential model (TBIPEP) show a good agreement with available experimental data

  2. Evolution of laser damage in indium antimonide(InSb) at 1.06-μm wavelength

    Science.gov (United States)

    Garg, Amit; Tripathi, K. N.; Kapoor, Avinashi; Bansal, S. K.

    2005-01-01

    Evolution of laser damage morphology has been studied in 112 oriented, mirror polished Indium Antimonide(InSb)samples as a function of increasing energy, pulse repetition rate and number of pulses using a Nd:Cr:GSGG laser of 1.06 μm wavelength having a pulse width of 20ns. Scanning Electron Microscope (SEM) investigations of the irradiated samples have been done to understand the evolution of damage morphology. Damage morphology is consistent with surface melting and solidification along with an evidence of subsurface overheating. Temperature profiles calculated at different fluence levels confirm substantial subsurface heating. Multiple pulse damage seen at 20Hz with increasing fluence levels is mainly thermal damage. Thermal modeling has been done to explain different morphological features.

  3. The crystal structure of the new ternary antimonide Dy3Cu20+xSb11-x (x∼2)

    International Nuclear Information System (INIS)

    New ternary antimonide Dy3Cu20+xSb11-x (x∼2) was synthesized and its crystal structure was determined by direct methods from X-ray powder diffraction data (diffractometer DRON-3M, CuKα-radiation, RI=6.99%,Rp=12.27%,Rwp=11.55%). The compound crystallizes with the own cubic structure type: space group F4-bar 3m, Pearson code cF272, a=16.6150(2)A,Z=8. The structure of the Dy3Cu20Sb11-x (x∼2) can be obtained from the structure type BaHg11 by doubling of the lattice parameter and subtraction of 16 atoms. The studied structure was compared with the structures of known compounds, which crystallize in the same space group with similar cell parameters

  4. The crystal structure of the new ternary antimonide Dy 3Cu 20+xSb 11-x ( x≈2)

    Science.gov (United States)

    Fedyna, L. O.; Bodak, O. I.; Fedorchuk, A. O.; Tokaychuk, Ya. O.

    2005-06-01

    New ternary antimonide Dy 3Cu 20+xSb 11-x ( x≈2) was synthesized and its crystal structure was determined by direct methods from X-ray powder diffraction data (diffractometer DRON-3M, Cu Kα-radiation, R=6.99%,R=12.27%,R=11.55%). The compound crystallizes with the own cubic structure type: space group F 4¯ 3m, Pearson code cF272, a=16.6150(2) Å,Z=8. The structure of the Dy 3Cu 20Sb 11-x ( x≈2) can be obtained from the structure type BaHg 11 by doubling of the lattice parameter and subtraction of 16 atoms. The studied structure was compared with the structures of known compounds, which crystallize in the same space group with similar cell parameters.

  5. The crystal structure of a new ternary antimonide: TmCu4-xSb2 (x 1.065)

    International Nuclear Information System (INIS)

    The crystal structure of the new ternary compound TmCu4-xSb2 (x 1.065) was determined by direct methods from X-ray powder data (diffractometer DRON-3M, Cu Kα-radiation). It crystallizes with the orthorhombic structure type ErFe4Ge2 (low-temperature modification) and is the first representative of this structure type among known antimonides: space group Pnnm, Pearson code oP14-2.13, a = 7.00565(6) A, b = 7.83582(6) A, c = 4.25051(3) A, Z = 2. Investigated structure is an orthorhombically deformed derivative of the ZrFe4Si2 structure type

  6. Influence of deposition temperature on the microstructure and thermoelectric properties of antimonide cobalt thin films prepared by ion beam sputtering deposition

    International Nuclear Information System (INIS)

    Highlights: • Co–Sb films were prepared by ion beam sputtering using fan-shape target. • The carrier concentration is suitable for obtaining high-quality sample. • Co–Sb thin film with mixed CoSb3 and Sb phase has highest power factor. - Abstract: Antimonide cobalt thin films were deposited on BK7 glass substrates at various substrate temperatures by ion beam sputtering deposition with a fan-shape target. The influence of deposition temperature on the microstructure and thermoelectric properties of antimonide cobalt thin films were systematically investigated. It is found that the Seebeck coefficient of the thin film increases at first and then decreases with the increasing deposition temperature. The Seebeck coefficient of the sample deposited at 250 °C has maximum value and increases stably when the measuring temperature increased from room-temperature to 600 K. The electrical conductivity of the thin film increases significantly to 5.6 × 104 S cm−1 when the deposition temperature was 450 °C and then decreases greatly when the temperature increased to 500 °C and 550 °C. The behavior of electrical conductivity of the sample deposited at 250 °C changes from metallic to semiconducting after the measuring temperature exceeded 540 K. The power factor of antimonide cobalt thin film deposited at 250 °C has a maximum value of 0.93 × 10−4 W m−1 K−2 at room-temperature and then increases to 3.5 × 10−4 W m−1 K−2 when the measuring temperature was 540 K

  7. Structural and 121Sb M\\"ossbauer Spectroscopic Investigations of the Antimonide Oxides REMnSbO (RE = La, Ce, Pr, Nd, Sm, Gd, Tb) and REZnSbO (RE = La, Ce, Pr)

    OpenAIRE

    Schellenberg, Inga; Nilges, Tom; Pöttgen, Rainer

    2008-01-01

    The quaternary antimonide oxides REMnSbO (RE = La, Ce, Pr, Nd, Sm, Gd, Tb) and REZnSbO (RE = La, Ce, Pr) were synthesized from the RESb monoantimonides and MnO, respectively ZnO. We report on single crystal X-ray data and a detailed 121Sb M\\"ossbauer spectroscopic investigation.

  8. Effect of residual gaseous impurities on the dewetting of antimonide melts in fused silica crucibles in the case of bulk crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Sylla, L. [SIMAP-EPM, ENSEEG, BP 75, 38402 Saint Martin d' Heres (France)], E-mail: lamine.sylla@gmail.com; Paulin, J.P.; Vian, G.; Garnier, C.; Duffar, T. [SIMAP-EPM, ENSEEG, BP 75, 38402 Saint Martin d' Heres (France)

    2008-11-15

    A Bridgman set-up has been modified to perform the contactless growth ('dewetting') of gallium and indium antimonide compounds in fused silica crucibles. According to wetting parameters measured by the sessile drop method given in the literature, both molten InSb and GaSb compounds are considered as non-reactive with silica substrates. A detailed description of the experimental set-up is presented. Each polycrystalline sample is inserted in a sealed silica crucible that is backfilled with industrial argon containing a few ppm of oxygen. Under similar experimental conditions, the dewetted growth of GaSb is much easier to obtain than that for InSb. The presence of residual impurities such as oxygen in the backfilling gas appears to enhance the occurrence of the phenomenon for GaSb.

  9. Effect of residual gaseous impurities on the dewetting of antimonide melts in fused silica crucibles in the case of bulk crystal growth

    International Nuclear Information System (INIS)

    A Bridgman set-up has been modified to perform the contactless growth ('dewetting') of gallium and indium antimonide compounds in fused silica crucibles. According to wetting parameters measured by the sessile drop method given in the literature, both molten InSb and GaSb compounds are considered as non-reactive with silica substrates. A detailed description of the experimental set-up is presented. Each polycrystalline sample is inserted in a sealed silica crucible that is backfilled with industrial argon containing a few ppm of oxygen. Under similar experimental conditions, the dewetted growth of GaSb is much easier to obtain than that for InSb. The presence of residual impurities such as oxygen in the backfilling gas appears to enhance the occurrence of the phenomenon for GaSb

  10. Sensitive detection of carbon monoxide based on a QEPAS sensor with a 2.3 μm fiber-coupled antimonide diode laser

    International Nuclear Information System (INIS)

    In this paper, a sensitive quartz-enhanced photoacoustic spectroscopy (QEPAS)–based carbon monoxide (CO) sensor using a 2.3 μm continuous wave (CW) distributed feedback (DFB) fiber-coupled antimonide diode laser is demonstrated for the first time. Wavelength modulation spectroscopy and a second-harmonic detection technique are used to reduce the sensor background noise and simplify the data process. Water vapor is added into a 1000 ppm CO:N2 gas mixture to improve the vibrational–translational relaxation rate of the analyzed CO for the purpose of enhancement of the QEPAS signal. After the modulation depth is optimized, a minimum detection limit of 43.3 ppm at the 4294.6 cm−1 absorption line is achieved when the modulation depth is set to 0.32 cm−1. (paper)

  11. Theoretical investigations on vibrational properties and thermal conductivities of ternary antimonides TiXSb, ZrXSb and HfXSb (X = Si, Ge)

    Science.gov (United States)

    Deligoz, E.; Ozyar, U. F.; Ozisik, H. B.

    2016-06-01

    We have performed density functional calculations of the vibrational and thermodynamic properties of the ternary antimonides TiXSb, ZrXSb and HfXSb (X = Si, Ge). The direct method is used to calculate the phonon dispersion relation and phonon density of states for these compounds as well as their infrared and Raman active mode frequencies for the first time. Their dynamical stability is confirmed by phonon spectra. The lattice thermal conductivities of these compounds have been calculated from third-order force constants and plotted as a function of temperature. We have also evaluated the high temperature thermal conductivity by means of the Clarke's model and Cahill's model. Some selected thermodynamical properties, e.g. Gibbs free energy, entropy and heat capacity at constant volume are predicted theoretically and discussed. We have showed the relationships between thermodynamical properties and temperature. The numerical calculations reported in this paper were partially performed at Aksaray University, Science and Technology Application and Research Center.

  12. Differences and similarities between the isotypic antimonides MFe1-xSb, ScCo1-xSb, and MNiSb (M = Zr, Hf)

    International Nuclear Information System (INIS)

    The new antimonides MFe1-xSb can be synthesized by arc-melting of M, Fe, and MSb2 (M = Zr, Hf). All title compounds crystallize in the TiNiSi structure type (space group Pnma, Z = 4). The lattice parameters of the new phases of MFe1-xSb, as obtained from the bulk samples of the nominal compositions MFeSb, are a = 681.4(1) pm, b = 417.87(7) pm, c = 740.3(1) pm for ZrFe1-xSb and a = 674.0(1) pm, b = 412.0(2) pm, c = 729.7(2) pm for HfFe1-xSb. Under the reaction conditions used, the occupancy factors of the iron position content of ZrFe1-xSb does not exceed 68(1)% (i.e., x = 0.32(1)). Extended Hueckel calculations, performed on the hypothetical model structures ZrFeSb and ZrFe0.75Sb, point to the phase ZrFe1-xSb being metallic, independent of the x value. The band structure of ZrFeSb, obtained with ab initio LMTO calculations, reveals a three-dimensional metallic conductivity and a nonmagnetic ground state

  13. The layered antimonides RELi{sub 3}Sb{sub 2} (RE=Ce–Nd, Sm, Gd–Ho). Filled derivatives of the CaAl{sub 2}Si{sub 2} structure type

    Energy Technology Data Exchange (ETDEWEB)

    Schäfer, Marion C.; Suen, Nian-Tzu; Raglione, Michaella; Bobev, Svilen, E-mail: bobev@udel.edu

    2014-02-15

    Reported are the synthesis and the structural characterization of an extended family of rare-earth metal–lithium–antimonides with the formula RELi{sub 3}Sb{sub 2} (RE=Ce–Nd, Sm, Gd–Ho). They crystallize in the trigonal space group P3{sup ¯}m1 (No. 164, Pearson symbol hP6) with a structure, best viewed as a filled derivative of the common CaAl{sub 2}Si{sub 2} structure type (ternary variant of α-La{sub 2}O{sub 3}). Across the series, the lattice parameters monotonically decrease, following the lanthanide contraction. Temperature-dependent magnetic susceptibility measurements for CeLi{sub 3}Sb{sub 2}, PrLi{sub 3}Sb{sub 2} and TbLi{sub 3}Sb{sub 2} reveal paramagnetic behavior in the high temperature range, and the obtained effective moments are consistent with the expected ones for the free-ion RE{sup 3+} ground state. Possible ferromagnetic ordering for PrLi{sub 3}Sb{sub 2} and antiferromagnetic ordering for TbLi{sub 3}Sb{sub 2} are observed in the low temperature range (below 20 K). Tight-binding muffin-tin orbital electronic band structure calculations for LaLi{sub 3}Sb{sub 2} are presented and discussed as well. - Graphical abstract: The large family of rare-earth metal–lithium–antimonides with the formula RELi{sub 3}Sb{sub 2} (RE=Ce–Nd, Sm, Gd–Ho) crystallize in the trigonal space group P3{sup ¯}m1 (No. 164, Pearson symbol hP6) with a structure that is a filled derivative of the CaAl{sub 2}Si{sub 2} structure type (ternary variant of α-La{sub 2}O{sub 3}). Display Omitted - Highlights: • RELi{sub 3}Sb{sub 2} (RE=Ce–Nd, Sm, Gd–Ho) constitute an extended family of rare-earth metal–lithium–antimonides. • The layered structure is a filled derivative of the common CaAl{sub 2}Si{sub 2} structure type. • The valence electron count follows the Zintl–Klemm rules. • Electronic band structure calculations for LaLi{sub 3}Sb{sub 2} indicate small band-gap semiconducting behavior.

  14. Structural and {sup 121}Sb Moessbauer spectroscopic investigations of the antimonide oxides REMnSbO (RE = La, Ce, Pr, Nd, Sm, Gd, Tb) and REZnSbO (RE = La, Ce, Pr)

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, I.; Nilges, T.; Poettgen, R. [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2008-07-15

    Quaternary antimonide oxides REMnSbO (RE = La, Ce, Pr, Nd, Sm, Gd, Tb) and REZnSbO (RE = La, Ce, Pr) were synthesized from the RESb monoantimonides and MnO, respectively ZnO, in sealed tubes at 1170 K. Single crystals were obtained from NaCl/KCl salt fluxes. The ZrCuSiAs-type (space group P4/nmm) structures of LaMnSbO (a = 423.95(7), c = 955.5(27) pm, wR2 = 0.067, 247 F{sup 2}), CeMnSbO (a = 420.8(1), c = 950.7(1) pm, wR2 = 0.097, 250 F{sup 2}), SmMnSbO (a = 413.1(1), c = 942.3(1) pm, wR2 = 0.068, 330 F{sup 2}), LaZnSbO (a = 422.67(6), c = 953.8(2) pm, wR2 = 0.052, 259 F{sup 2}), and NdZnSbO (a = 415.9(1), c = 945.4(4) pm, wR2 = 0.109, 206 F{sup 2}) were refined from single crystal X-ray diffractometer data. The structures consist of covalently bonded (RE{sup 3+}O{sup 2-}){sup +} and (T{sup 2+}Sb{sup 3-}){sup -} layers with weak ionic interlayer interactions. The oxygen and transition metal atoms both have tetrahedral coordination within the layers. {sup 121}Sb Moessbauer spectra of the REMnSbO and REZnSbO compounds show single antimony sites with isomer shifts close to -8 mm s{sup -1}, in agreement with the antimonide character of these compounds. PrMnSbO and NdMnSbO show transferred hyperfine fields of 8 T at 4.2 K. (orig.)

  15. Ternary antimonides RE{sub 4}T{sub 7}Sb{sub 6} (RE = Gd-Lu; T = Ru, Rh) with cubic U{sub 4}Re{sub 7}Si{sub 6}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, Inga; Rodewald, Ute C.; Schwickert, Christian; Eul, Matthias; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2013-09-15

    The ternary antimonides RE{sub 4}T{sub 7}Sb{sub 6} (RE = Gd-Lu; T = Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U{sub 4}Re{sub 7}Si{sub 6} type, space group Im anti 3m with a = 862.9(2) pm, wR2 = 0.0296, 163 F{sup 2} values for Er{sub 4}Ru{sub 7}Sb{sub 6}; a = 864.1(1) pm, wR2 = 0.1423, 153 F{sup 2} values for Yb{sub 4}Ru{sub 7}Sb{sub 6}; a = 872.0(2) pm, wR2 = 0.0427, 172 F{sup 2} values for Tb{sub 4}Rh{sub 7}Sb{sub 6}; and a = 868.0(2) pm, wR2 = 0.0529, 154 F{sup 2} values for Er{sub 4}Rh{sub 7}Sb{sub 6}, with 10 variables per refinement. The structures have T1 rate at Sb{sub 6} octahedra and slightly distorted RE rate at T2{sub 6}Sb{sub 6} cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu{sub 4}Ru{sub 7}Sb{sub 6} is Pauli-paramagnetic. The antimonides RE{sub 4}Ru{sub 7}Sb{sub 6} with RE = Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy{sub 4}Ru{sub 7}Sb{sub 6}, Ho{sub 4}Ru{sub 7}Sb{sub 6} and Er{sub 4}Ru{sub 7}Sb{sub 6}, respectively, while Tm{sub 4}Ru{sub 7}Sb{sub 6} remains paramagnetic. Yb{sub 4}Ru{sub 7}Sb{sub 6} is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) {mu}{sub B} per Yb as compared to 4.54 {mu}{sub B} for a free Yb{sup 3+} ion. (orig.)

  16. Alkaline earth filled nickel skutterudite antimonide thermoelectrics

    Science.gov (United States)

    Singh, David Joseph

    2013-07-16

    A thermoelectric material including a body centered cubic filled skutterudite having the formula A.sub.xFe.sub.yNi.sub.zSb.sub.12, where A is an alkaline earth element, x is no more than approximately 1.0, and the sum of y and z is approximately equal to 4.0. The alkaline earth element includes guest atoms selected from the group consisting of Be, Mb, Ca, Sr, Ba, Ra and combinations thereof. The filled skutterudite is shown to have properties suitable for a wide variety of thermoelectric applications.

  17. Ternary rare-earth titanium antimonides: Phase equilibria in the RE-Ti-Sb (RE=La, Er) systems and crystal structures of RE2Ti7Sb12 (RE=La, Ce, Pr, Nd) and RETi3(SnxSb1-x)4 (RE=Nd, Sm)

    International Nuclear Information System (INIS)

    Investigations on phase relationships and crystal structures have been conducted on several ternary rare-earth titanium antimonide systems. The isothermal cross-sections of the ternary RE-Ti-Sb systems containing a representative early (RE=La) and late rare-earth element (RE=Er) have been constructed at 800 deg. C. In the La-Ti-Sb system, the previously known compound La3TiSb5 was confirmed and the new compound La2Ti7Sb12 (own type, Cmmm, Z=2, a=10.5446(10) A, b=20.768(2) A, and c=4.4344(4) A) was discovered. In the Er-Ti-Sb system, no ternary compounds were found. The structure of La2Ti7Sb12 consists of a complex arrangement of TiSb6 octahedra and disordered fragments of homoatomic Sb assemblies, generating a three-dimensional framework in which La atoms reside. Other early rare-earth elements (RE=Ce, Pr, Nd) can be substituted in this structure type. Attempts to prepare crystals in these systems through use of a tin flux resulted in the discovery of a new Sn-containing pseudoternary phase RETi3(SnxSb1-x)4 for RE=Nd, Sm (own type, Fmmm, Z=8; a=5.7806(4) A, b=10.0846(7) A, and c=24.2260(16) A for NdTi3(Sn0.1Sb0.9)4; a=5.7590(4) A, b=10.0686(6) A, and c=24.1167(14) A for SmTi3(Sn0.1Sb0.9)4). Its structure consists of double-layer slabs of Ti-centred octahedra stacked alternately with nets of the RE atoms; the Ti atoms are arranged in kagome nets. - Graphical abstract: La2Ti7Sb12 contains sectioned layers consisting of Ti-centred octahedra linked by corner- and face-sharing

  18. Wet chemistry synthesis towards nanostructures of thermoelectric antimonides

    OpenAIRE

    Birkel, Christina

    2010-01-01

    Die vorliegende Arbeit befasst sich mit der Synthese von nanostrukturierten Antimoniden, wobei die folgenden beiden Themen bearbeitet wurden: rnAus chemischer Sicht wurden neue Synthesewege entwickelt, um Nanopartikel der Verbindungen in den binären Systemen Zn-Sb und Fe-Sb herzustellen (Zn4Sb3, ZnSb, FeSb2, Fe1+xSb). Anders als in konventionellen Festkörperreaktionen, die auf die Synthese von Bulk-Materialien oder Einkristallen zielen, muss die Synthese von Nanopartikeln Agglomerate und Ostw...

  19. Ternary and quaternary antimonide devices for thermophotovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Hitchcock, C.W.; Gutmann, R.J.; Ehsani, H.; Bhat, I.B. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Integrated Electronics and Electronics Manufacturing; Wang, C.A. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Freeman, M.J.; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

    1998-06-01

    Thermophotovoltaic (TPV) devices have been fabricated using epitaxial ternary and quaternary layers grown on GaSb substrates. GaInSb ternary devices were grown by metalorganic vapor phase epitaxy (MOVPE) with buffer layers to accommodate the lattice mismatch, and GaInAsSb lattice-matched quaternaries were grown by MOVPE and by liquid phase epitaxy (LPE). Improved devices are obtained when optical absorption occurs in the p-layer due to the longer minority carrier diffusion length. Thick emitter p/n devices are limited by surface recombination, with highest quantum efficiency and lowest dark current being achieved with epitaxially grown surface passivation layers on lattice-matched MOVPE quaternaries. Thin emitter/thick base n/p devices are very promising, but require improved shallow high-quality n-type ohmic contacts.

  20. Studies on the UFeSb2 uranium antimonide

    International Nuclear Information System (INIS)

    UFe1-xSb2 is a ternary uranium phase that crystallizes in the tetragonal HfCuSi2-type structure (SG. P4/nmm) [1], the U and Fe atoms being located in one position (2c and 2b, respectively), while Sb occupies two sites (2a and 2c). This phase is closely related to the USb2 binary compound (Cu2Sb-type structure, SG. P4/nmm), which is a layered structure with Sb(I), U and Sb(II) sheets stacked along the c axis: UFe1-xSb2 can be seen as formed from USb2 by inserting an additional Fe layer between the planes that compose the Sb(II) sheets. UFeSb2 is the limit compound in of this homogeneity range. Its crystal structure (HfCuSi2-type), unit cell parameters and electrical resistivity as a function of temperature were already reported

  1. Study of the surface of the electrolytically oxidized indium antimonide

    International Nuclear Information System (INIS)

    The composition and properties of the surface of electrolytically oxidized InSb are investigated. The relief and structure of electrolytically oxidized InSb surface, thickness and composition of the oxidized film have been found. A surface layer dehydration scheme is proposed. It is shown that anodic oxide film is represented mainly by In oxides wth possible disseminations of antimony

  2. Czochralski growth of gallium indium antimonide alloy crystals

    Energy Technology Data Exchange (ETDEWEB)

    Tsaur, S.C.

    1998-02-01

    Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform compositions up to nearly 5 mole% InSb.

  3. Thermal emittance and response time of a cesium antimonide photocathode

    Science.gov (United States)

    Cultrera, Luca; Bazarov, Ivan; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Merluzzi, Richard; Nichols, Matthew

    2011-10-01

    Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

  4. Thermal emittance measurements of a cesium potassium antimonide photocathode

    OpenAIRE

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-01-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56+/-0.03 mm-mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  5. Thermal emittance measurements of a cesium potassium antimonide photocathode

    Science.gov (United States)

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-05-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56±0.03 mm mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  6. Thermoelectric properties of cobalt–antimonide thin films prepared by radio frequency co-sputtering

    International Nuclear Information System (INIS)

    Co–Sb thin films with an Sb content in the range 65–76 at.%, were deposited on a thermally oxidized Si (100) substrate preheated at 200 °C using radio-frequency co-sputtering. Evaluation using scanning electron microscopy images and X-ray diffraction reveals that the films were polycrystalline, with a grain size in the range 100–250 nm. Energy-dispersive spectroscopy analysis indicates single-phase CoSb2 and CoSb3 films, as well as multiphase thin films with either CoSb2 or CoSb3 as the dominant phase. The electrical and thermoelectric properties were measured and found to be strongly dependent on the observed phases and the defect concentrations. The CoSb2 thin films were found to exhibit a significant n-type thermoelectric effect, which, coupled with the very low electrical resistivity, resulted in a larger power factor than that of the CoSb3 thin films. We find power factors of 0.73 mWm−1 K−2 and 0.67 mWm−1 K−2 for the CoSb2 and CoSb3 thin films, respectively. - Highlights: • Polycrystalline Co–Sb thin films were obtained by present deposition strategy. • CoSb2 and CoSb3 have semimetal and semiconductor characteristics respectively. • The Seebeck coefficient depends heavily on defect concentration and impurity phases. • Film properties in the second heating cycle were different from the first. • CoSb2 is found to possess significant n-type thermopower

  7. Growth of High Material Quality Group III-Antimonide Semiconductor Nanowires by a Naturally Cooling Process.

    Science.gov (United States)

    Li, Kan; Pan, Wei; Wang, Jingyun; Pan, Huayong; Huang, Shaoyun; Xing, Yingjie; Xu, H Q

    2016-12-01

    We report on a simple but powerful approach to grow high material quality InSb and GaSb nanowires in a commonly used tube furnace setup. The approach employs a process of stable heating at a high temperature and then cooling down naturally to room temperature with the nanowire growth occurred effectively during the naturally cooling step. As-grown nanowires are analyzed using a scanning electron microscope and a transmission electron microscope equipped with an energy-dispersive X-ray spectroscopy setup. It is shown that the grown nanowires are several micrometers in lengths and are zincblende InSb and GaSb crystals. The FET devices are also fabricated with the grown nanowires and investigated. It is shown that the grown nanowires show good, desired electrical properties and should have potential applications in the future nanoelectronics and infrared optoelectronics. PMID:27112353

  8. Thermoelectric properties of cobalt–antimonide thin films prepared by radio frequency co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Aziz; Han, Seungwoo, E-mail: swhan@kimm.re.kr

    2015-07-31

    Co–Sb thin films with an Sb content in the range 65–76 at.%, were deposited on a thermally oxidized Si (100) substrate preheated at 200 °C using radio-frequency co-sputtering. Evaluation using scanning electron microscopy images and X-ray diffraction reveals that the films were polycrystalline, with a grain size in the range 100–250 nm. Energy-dispersive spectroscopy analysis indicates single-phase CoSb{sub 2} and CoSb{sub 3} films, as well as multiphase thin films with either CoSb{sub 2} or CoSb{sub 3} as the dominant phase. The electrical and thermoelectric properties were measured and found to be strongly dependent on the observed phases and the defect concentrations. The CoSb{sub 2} thin films were found to exhibit a significant n-type thermoelectric effect, which, coupled with the very low electrical resistivity, resulted in a larger power factor than that of the CoSb{sub 3} thin films. We find power factors of 0.73 mWm{sup −1} K{sup −2} and 0.67 mWm{sup −1} K{sup −2} for the CoSb{sub 2} and CoSb{sub 3} thin films, respectively. - Highlights: • Polycrystalline Co–Sb thin films were obtained by present deposition strategy. • CoSb{sub 2} and CoSb{sub 3} have semimetal and semiconductor characteristics respectively. • The Seebeck coefficient depends heavily on defect concentration and impurity phases. • Film properties in the second heating cycle were different from the first. • CoSb{sub 2} is found to possess significant n-type thermopower.

  9. Novel strongly correlated electron states in filled skutterudite lanthanide osmium antimonides

    International Nuclear Information System (INIS)

    Recent measurements on the filled skutterudite compounds Pr(Os1-xRux)4Sb12, NdOs4Sb12, and SmOs4Sb12 are discussed. Pr(Os1-xRux)4Sb12 displays superconductivity for all values of x with a minimum at x=0.6, and only the compounds with x4Sb12 and the BCS superconductivity of PrRu4Sb12. NdOs4Sb12 is a heavy fermion ferromagnet, with a sharp transition observed at 1.0K. SmOs4Sb12 is also a heavy fermion material, and it may display weak ferromagnetic behavior below 2.6K

  10. Novel strongly correlated electron states in filled skutterudite lanthanide osmium antimonides

    Energy Technology Data Exchange (ETDEWEB)

    Maple, M.B. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States)]. E-mail: mbmaple@physics.ucsd.edu; Frederick, N.A. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States); Ho, P.-C. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States); Yuhasz, W.M. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States); Sayles, T.A. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States); Butch, N.P. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States); Jeffries, J.R. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States); Taylor, B.J. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California at San Diego, La Jolla, CA 92093 (United States)

    2005-04-30

    Recent measurements on the filled skutterudite compounds Pr(Os{sub 1-x}Ru{sub x}){sub 4}Sb{sub 12}, NdOs{sub 4}Sb{sub 12}, and SmOs{sub 4}Sb{sub 12} are discussed. Pr(Os{sub 1-x}Ru{sub x}){sub 4}Sb{sub 12} displays superconductivity for all values of x with a minimum at x=0.6, and only the compounds with x<0.6 display heavy fermion characteristics, suggesting a competition between the unconventional heavy fermion superconductivity of PrOs{sub 4}Sb{sub 12} and the BCS superconductivity of PrRu{sub 4}Sb{sub 12}. NdOs{sub 4}Sb{sub 12} is a heavy fermion ferromagnet, with a sharp transition observed at 1.0K. SmOs{sub 4}Sb{sub 12} is also a heavy fermion material, and it may display weak ferromagnetic behavior below 2.6K.

  11. Growth of High Material Quality Group III-Antimonide Semiconductor Nanowires by a Naturally Cooling Process

    Science.gov (United States)

    Li, Kan; Pan, Wei; Wang, Jingyun; Pan, Huayong; Huang, Shaoyun; Xing, Yingjie; Xu, H. Q.

    2016-04-01

    We report on a simple but powerful approach to grow high material quality InSb and GaSb nanowires in a commonly used tube furnace setup. The approach employs a process of stable heating at a high temperature and then cooling down naturally to room temperature with the nanowire growth occurred effectively during the naturally cooling step. As-grown nanowires are analyzed using a scanning electron microscope and a transmission electron microscope equipped with an energy-dispersive X-ray spectroscopy setup. It is shown that the grown nanowires are several micrometers in lengths and are zincblende InSb and GaSb crystals. The FET devices are also fabricated with the grown nanowires and investigated. It is shown that the grown nanowires show good, desired electrical properties and should have potential applications in the future nanoelectronics and infrared optoelectronics.

  12. Structural, morphological and Raman studies of pulse electrosynthesised indium antimonide thin films

    International Nuclear Information System (INIS)

    InSb films deposited on fluorine doped tin oxide (FTO) substrates by a pulse elctrodeposition technique. The deposition was carried out at an applied potential −1.3V versus Ag/AgCl electrode. Structural, morphological and optical studies were performed on the electrodeposited InSb. X-ray diffraction (XRD) studies show that the deposited InSb films are polycrystalline in nature having the zinc blend structure. The crystallite size (D), dislocation density (δ) and strain (ε) were calculated using XRD results. The EDAX analysis shows that chemical composition of In3+ and Sb3+ ions is close to the required stoichiometry. The surface morphology of the deposited films was examined using scanning electron microscopy (SEM). SEM studies reveal that the surface of the films is uniformly covered with submicron sized spherical particles. However, the crystallite size determined by the Scherrer method shows a size close to 30 nm. Surface morphology studies of the InSb films were also performed using atomic force microscopy (AFM). The average surface roughness as measured by AFM is around 40 nm. Hot probe studies show that all the electrodeposited thin films have n type conductivity and the thickness of the films is calculated using electrochemical formula

  13. Effect of Sb thickness on the performance of bialkali-antimonide photocathodes

    Energy Technology Data Exchange (ETDEWEB)

    Mamun, Md Abdullah A., E-mail: mmamu001@odu.edu; Elmustafa, Abdelmageed A. [Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, Virginia 23529 and The Applied Research Center, Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Hernandez-Garcia, Carlos; Mammei, Russell; Poelker, Matthew [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

    2016-03-15

    The alkali species Cs and K were codeposited using an effusion source, onto relatively thick layers of Sb (50 nm to ∼7 μm) grown on GaAs and Ta substrates inside a vacuum chamber that was baked and not-vented, and also baked and vented with clean dry nitrogen but not rebaked. The characteristics of the Sb films, including sticking probability, surface roughness, grain size, and crystal properties were very different for these conditions, yet comparable values of photocathode yield [or quantum efficiency (QE)] at 284 V were obtained following codeposition of the alkali materials. Photocathodes manufactured with comparatively thick Sb layers exhibited the highest QE and the best 1/e lifetime. The authors speculate that the alkali codeposition enabled optimized stoichiometry for photocathodes manufactured using thick Sb layers, which could serve as a reservoir for the alkali materials.

  14. Thermal oxidation of single crystal aluminum antimonide and materials having the same

    Science.gov (United States)

    Sherohman, John William; Yee, Jick Hong; Coombs, III, Arthur William; Wu, Kuang Jen J.

    2012-12-25

    In one embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a partial vacuum atmosphere at a temperature conducive for air adsorbed molecules to desorb, surface molecule groups to decompose, and elemental Sb to evaporate from a surface of the AlSb crystal and exposing the AlSb crystal to an atmosphere comprising oxygen to form a crystalline oxide layer on the surface of the AlSb crystal. In another embodiment, a method for forming a non-conductive crystalline oxide layer on an AlSb crystal includes heat treating an AlSb crystal in a non-oxidizing atmosphere at a temperature conducive for decomposition of an amorphous oxidized surface layer and evaporation of elemental Sb from the AlSb crystal surface and forming stable oxides of Al and Sb from residual surface oxygen to form a crystalline oxide layer on the surface of the AlSb crystal.

  15. Structural, morphological and Raman studies of pulse electrosynthesised indium antimonide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Joginder, E-mail: joginderchauhan82@gmail.com; Chandel, Tarun; Rajaram, P. [School of Studies in Physics, Jiwaji University, Gwalior (MP), India-474011 (India)

    2015-08-28

    InSb films deposited on fluorine doped tin oxide (FTO) substrates by a pulse elctrodeposition technique. The deposition was carried out at an applied potential −1.3V versus Ag/AgCl electrode. Structural, morphological and optical studies were performed on the electrodeposited InSb. X-ray diffraction (XRD) studies show that the deposited InSb films are polycrystalline in nature having the zinc blend structure. The crystallite size (D), dislocation density (δ) and strain (ε) were calculated using XRD results. The EDAX analysis shows that chemical composition of In{sup 3+} and Sb{sup 3+} ions is close to the required stoichiometry. The surface morphology of the deposited films was examined using scanning electron microscopy (SEM). SEM studies reveal that the surface of the films is uniformly covered with submicron sized spherical particles. However, the crystallite size determined by the Scherrer method shows a size close to 30 nm. Surface morphology studies of the InSb films were also performed using atomic force microscopy (AFM). The average surface roughness as measured by AFM is around 40 nm. Hot probe studies show that all the electrodeposited thin films have n type conductivity and the thickness of the films is calculated using electrochemical formula.

  16. Integrated array of 2-mum antimonide-based single-photon counting devices

    OpenAIRE

    Diagne, M.A.; Greszik, M.; Duerr, E.K.; Zayhowski, J.J.; Manfra, M. J.; Bailey, R J; Donnelly, J. P.; Turner, G.W.

    2011-01-01

    A 32x32 Sb-based Geiger-mode (GM) avalanche photodiode array, operating at 2 mum with three-dimensional imaging capability, is presented. The array is interfaced with a ROIC (readout integrated circuit) in which each pixel can detect a photon and record the arrival time. The hybridized unit for the 1000-element focal plane array, when operated at 77K with 1 V overbias range, shows an average dark count rate of 1.5 kHz. Three-dimensional range images of objects were acquired.

  17. Integrated array of 2-μm antimonide-based single-photon counting devices.

    Science.gov (United States)

    Diagne, M A; Greszik, M; Duerr, E K; Zayhowski, J J; Manfra, M J; Bailey, R J; Donnelly, J P; Turner, G W

    2011-02-28

    A 32x32 Sb-based Geiger-mode (GM) avalanche photodiode array, operating at 2 μm with three-dimensional imaging capability, is presented. The array is interfaced with a ROIC (readout integrated circuit) in which each pixel can detect a photon and record the arrival time. The hybridized unit for the 1000-element focal plane array, when operated at 77K with 1 V overbias range, shows an average dark count rate of 1.5 kHz. Three-dimensional range images of objects were acquired. PMID:21369250

  18. Chemical bonding and properties of "layered" quaternary antimonide oxide REOZnSb (RE = La, Ce, Pr, Nd).

    Science.gov (United States)

    Guo, Kai; Man, Zhen-Yong; Wang, Xiao-Jun; Chen, Hao-Hong; Tang, Mei-Bo; Zhang, Zhi-Jun; Grin, Yuri; Zhao, Jing-Tai

    2011-10-21

    An efficient route to construct a three-dimensional crystal structure is stacking of two-dimensional building blocks (2D-BBs). The crystal structures of potential thermoelectric compounds REOZnSb (RE = La, Ce, Pr, Nd) were virtually constructed from insulating [REO] and conducting [ZnSb] layers. Further optimizations performed by means of first-principles calculations show that REOZnSb should exhibit semimetal or narrow band-gap semiconductor behaviors, which is a prerequisite for high thermoelectric efficiency. The analysis of the electron localizability indicator for LaOZnSb reveals mostly covalent polar interactions between all four kinds of atoms. The electron density yields completely balanced ionic-like electronic formula La(1.7+)O(1.2-)Zn(0.4+)Sb(0.9-). Furthermore, the samples of REOZnSb have been synthesized via solid-state reaction, and their crystal structures were confirmed by powder X-ray diffraction. The differences in cell parameters between the theoretically optimized and the experimental values are smaller than 2%. The temperature dependence of the magnetic susceptibility shows that LaOZnSb is diamagnetic above 40 K, whereas CeOZnSb, PrOZnSb and NdOZnSb are Curie-Weiss-type paramagnets. Electrical conductivity and Seebeck effect measurements indicate that REOZnSb are p-type semiconductors. A considerably high Seebeck coefficient and low thermal conductivity were obtained for pure LaOZnSb, but its low electrical conductivity leads to a small ZT. The high adjustability of the crystal structure as well as properties by optimization of the chemical composition in the compounds REOZnSb provide good prospects for achieving high thermoelectric efficiency. PMID:21897929

  19. Gravitational influences on the liquid-state homogenization and solidification of aluminum antimonide. [space processing of solar cell material

    Science.gov (United States)

    Ang, C.-Y.; Lacy, L. L.

    1979-01-01

    Typical commercial or laboratory-prepared samples of polycrystalline AlSb contain microstructural inhomogeneities of Al- or Sb-rich phases in addition to the primary AlSb grains. The paper reports on gravitational influences, such as density-driven convection or sedimentation, that cause microscopic phase separation and nonequilibrium conditions to exist in earth-based melts of AlSb. A triple-cavity electric furnace is used to homogenize the multiphase AlSb samples in space and on earth. A comparative characterization of identically processed low- and one-gravity samples of commercial AlSb reveals major improvements in the homogeneity of the low-gravity homogenized material.

  20. Synthesis and characterization of mono- and di-antimonide with the first transition metals in group 8B by mechanical alloying

    International Nuclear Information System (INIS)

    Mono- and di-anitimonide compounds between antimony and the first transition metals in group 8B were synthesized by mechanical alloying method. All samples were investigated by the X-ray powder diffraction technique and differential thermal analysis. The single phase can be obtained only for CoSb, NiSb and CoSb2 compounds. In this investigation, a single phase of a marcasite structure (FeSb2 and NiSb2) and Fe0.56Sb0.44 compound cannot be detected in the XRD patterns after 60 h of milling because of the instability of their structures at low temperature. They decomposed to their starting materials as seen by the characteristic peaks of the starting materials in the XRD patterns after 60 h of milling.

  1. Synthesis and characterization of mono- and di-antimonide with the first transition metals in group 8B by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Amornpitoksuk, Pongsaton, E-mail: ampongsa@yahoo.co [Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla, 90112 (Thailand); Suwanboon, Sumetha [Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla, 90112 (Thailand); Ratana, Tanakorn [Industrial Chemistry Department, Faculty of Science, King Mongkut' s University of Technology North Bangkok, Bangkok, 10800 (Thailand); Ratana, Tanattha [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok, 10140 (Thailand)

    2010-07-02

    Mono- and di-anitimonide compounds between antimony and the first transition metals in group 8B were synthesized by mechanical alloying method. All samples were investigated by the X-ray powder diffraction technique and differential thermal analysis. The single phase can be obtained only for CoSb, NiSb and CoSb{sub 2} compounds. In this investigation, a single phase of a marcasite structure (FeSb{sub 2} and NiSb{sub 2}) and Fe{sub 0.56}Sb{sub 0.44} compound cannot be detected in the XRD patterns after 60 h of milling because of the instability of their structures at low temperature. They decomposed to their starting materials as seen by the characteristic peaks of the starting materials in the XRD patterns after 60 h of milling.

  2. Tracking Sodium-Antimonide Phase Transformations in Sodium-Ion Anodes: Insights from Operando Pair Distribution Function Analysis and Solid-State NMR Spectroscopy

    OpenAIRE

    Allan, Phoebe K.; Griffin, John M; Darwiche, Ali; Borkiewicz, Olaf J.; Wiaderek, Kamila M.; Chapman, Karena W.; Morris, Andrew J.; Chupas, Peter J.; Monconduit, Laure; Grey, Clare P.

    2016-01-01

    Operando pair distribution function (PDF) analysis and ex situ ??Na magic-angle spinning solid-state nuclear magnetic resonance (MAS ssNMR) spectroscopy are used to gain insight into the alloying mechanism of high-capacity antimony anodes for sodium-ion batteries. Subtraction of the PDF of crystalline Na?Sb phases from the total PDF, an approach constrained by chemical phase information gained from ??Na ssNMR in reference to relevant model compounds, leads to the identification of two previou...

  3. First principles gas phase study of the structures, energetics and spectroscopic parameters of aluminium antimonide, AlxSby (x + y = 3,5), clusters1

    Science.gov (United States)

    Gohee, Pravesh; Abdallah, Hassan H.; Archibong, Edet F.; Ramasami, Ponnadurai

    2013-08-01

    Theoretical methods (DFT/B3LYP and MP2) have been used to optimize the geometries of the AlxSby (x + y = 3,5) clusters and their anions. Single point energy computations at CCSD(T) level have also been performed using the optimized B3LYP and MP2 structures. The basis sets used for Al and Sb atoms are 6-311+G(2d) and LANL2DZdp ECP, respectively. Harmonic vibrational frequency computations were carried out to confirm the nature of the stationary points. We report the structural and spectroscopic parameters of the named clusters. We also report the relative energy of the clusters, the vertical electron detachment energy, the adiabatic electron detachment energy and the adiabatic electron affinity. The most stable structures at the CCSD(T)//MP2 level are, the D∞h linear structure (AlSb2) and the C2vV-bent structure (AlSb2-), the C2vV-bent structure (Al2Sb and its anion), the C2v edge-capped tetrahedron (Al2Sb3 and its anion), the C2v trigonal bipyramidal structure (Al3Sb2 and its anion), the C4v square pyramidal (AlSb4) and a C2v ground structure for its anion, the C2v planar trapezoidal structure (Al4Sb) and the C2v edge-capped tetrahedron (Al4Sb-). The adiabatic electron affinities calculated at the CCSD(T)//MP2 level are 2.17 eV (AlSb2), 2.17 eV (Al2Sb), 2.38 eV (Al2Sb3), 2.76 eV (Al3Sb2), 2.21 eV (AlSb4) and 2.03 eV (Al4Sb). The findings of this research are analysed, discussed and compared with the analogous picnogenides clusters. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2013-30660-2

  4. Tracking Sodium-Antimonide Phase Transformations in Sodium-Ion Anodes: Insights from Operando Pair Distribution Function Analysis and Solid-State NMR Spectroscopy.

    Science.gov (United States)

    Allan, Phoebe K; Griffin, John M; Darwiche, Ali; Borkiewicz, Olaf J; Wiaderek, Kamila M; Chapman, Karena W; Morris, Andrew J; Chupas, Peter J; Monconduit, Laure; Grey, Clare P

    2016-02-24

    Operando pair distribution function (PDF) analysis and ex situ (23)Na magic-angle spinning solid-state nuclear magnetic resonance (MAS ssNMR) spectroscopy are used to gain insight into the alloying mechanism of high-capacity antimony anodes for sodium-ion batteries. Subtraction of the PDF of crystalline NaxSb phases from the total PDF, an approach constrained by chemical phase information gained from (23)Na ssNMR in reference to relevant model compounds, identifies two previously uncharacterized intermediate species formed electrochemically; a-Na(3-x)Sb (x ≈ 0.4-0.5), a structure locally similar to crystalline Na3Sb (c-Na3Sb) but with significant numbers of sodium vacancies and a limited correlation length, and a-Na(1.7)Sb, a highly amorphous structure featuring some Sb-Sb bonding. The first sodiation breaks down the crystalline antimony to form first a-Na(3-x)Sb and, finally, crystalline Na3Sb. Desodiation results in the formation of an electrode formed of a composite of crystalline and amorphous antimony networks. We link the different reactivity of these networks to a series of sequential sodiation reactions manifesting as a cascade of processes observed in the electrochemical profile of subsequent cycles. The amorphous network reacts at higher voltages reforming a-Na(1.7)Sb, then a-Na(3-x)Sb, whereas lower potentials are required for the sodiation of crystalline antimony, which reacts to form a-Na(3-x)Sb without the formation of a-Na(1.7)Sb. a-Na(3-x)Sb is converted to crystalline Na3Sb at the end of the second discharge. We find no evidence of formation of NaSb. Variable temperature (23)Na NMR experiments reveal significant sodium mobility within c-Na3Sb; this is a possible contributing factor to the excellent rate performance of Sb anodes. PMID:26824406

  5. Molecular beam epitaxy of gallium arsenide antimonide-based ultra-high-speed double heterojunction bipolar transistors and light emitting transistors

    Science.gov (United States)

    Wu, Bing-Ruey

    In this work, GaAsSb-based double heterojunction bipolar transistors (DHBTs) and light emitting transistors (LETs) are grown using gas source molecular beam epitaxy (GSMBE). High-speed GaAs0.5Sb0.5/InP DHBTs are developed through the exercise of GSMBE growth optimization, device fabrication, and characterization. By adjusting the growth temperature and V/III flux ratio, the optimal conditions for growing GaAs0.5Sb0.5 base are found to be at high growth temperature and low V/III ratio. The switching sequence is also optimized so that the Sb segregation effect is minimized. By using GaAs0.5Sb0.5-In0.2Ga0.8As 0.7Sb0.3 compositional grading in the base of the GaAsSb/InP DHBT, a significant improvement of fT from 380 GHz to 500 GHz was achieved compared to a uniform GaAs0.5Sb 0.5 DHBT, while maintaining a high breakdown voltage BVCEO ˜ 4V. The cutoff frequency---breakdown voltage product, fT·BVCEO, of over 2000 GHz-V, is the record value for DHBTs of any material system. Incorporating graded InAs-InGaAs emitter contact layer is also shown to effectively reduce the total emitter resistance, further improving the DHBT high speed performance. LET characteristics with quantum wells (QWs) inserted into the base region of GaAsSb/InP DHBTs are also investigated and the preliminary results are presented. An LET with a tensile strained InGaAsSb/GaAs0.65Sb 0.35 DQW in the base was designed and achieved the emission wavelength of ˜1.6 mum, despite of its low light output intensity. The potential and limitation of realizing a transistor laser with an emission wavelength of 1.55 mum using GaAsSb/InP material system will be discussed.

  6. Development of a Prototype 2 mm Fiber-Coupled Seed Laser for Integration in Lidar Transmitter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optimize the performance of Gallium Antimonide (GaSb)-based 2.05 mm lasers (previously developed under JPL’s Research and Technology Development (R&TD)...

  7. Semiconducting III-V compounds

    CERN Document Server

    Hilsum, C; Henisch, Heinz R

    1961-01-01

    Semiconducting III-V Compounds deals with the properties of III-V compounds as a family of semiconducting crystals and relates these compounds to the monatomic semiconductors silicon and germanium. Emphasis is placed on physical processes that are peculiar to III-V compounds, particularly those that combine boron, aluminum, gallium, and indium with phosphorus, arsenic, and antimony (for example, indium antimonide, indium arsenide, gallium antimonide, and gallium arsenide).Comprised of eight chapters, this book begins with an assessment of the crystal structure and binding of III-V compounds, f

  8. Design and performance of a dual-laser instrument for multiple isotopologues of carbon dioxide and water.

    Science.gov (United States)

    McManus, J Barry; Nelson, David D; Zahniser, Mark S

    2015-03-01

    A design and results for an instrument with a quantum cascade laser and an antimonide diode laser to measure simultaneously and with high precision seven isotopologues of carbon dioxide and water vapor. Methods and results for determining the effects that limit absorption noise at the level of 5x10(-6) are presented and discussed. PMID:25836875

  9. Performance test results on a miniature Stirling cryocooler for use in integrated dewar detector assemblies

    International Nuclear Information System (INIS)

    An Integral Stirling Minicooler has been introduced to operate with 'integrated' cooler/dewar structures. Performance of prototype units is being measured with platinum silicide, indium antimonide, lead selenide, and mercury cadmium telluride detector arrays. Results of tests on cooler capacity, power consumption, cooldown time, acoustic noise, and self-induced vibration are presented. 3 refs

  10. Interface engineering for improved growth of GaSb on Si(111)

    Czech Academy of Sciences Publication Activity Database

    Proessdorf, A.; Grosse, F.; Romanyuk, Olexandr; Braun, W.; Jenichen, B.; Trampert, A.; Riechert, H.

    2011-01-01

    Roč. 213, č. 1 (2011), 401-404. ISSN 0022-0248 Grant ostatní: AV CR - DFG(DE) Common Project AV CR - DFG Institutional research plan: CEZ:AV0Z10100521 Keywords : defects * RHEED * XRD * MBE * antimonides * III-V semiconductors Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.726, year: 2011

  11. Synthesis and thermoelectric properties of Sb0.20CoSb2.80 skutterudite

    International Nuclear Information System (INIS)

    Highlights: • A HP-HT Sb0.20CoSb2.80 phase was prepared by processing cobalt antimonide at 7.7 GPa and 550 °C, for (at least) 5 min. • The mechanism of formation of this phase involves (i) decomposition of cobalt antimonide into CoSb2 and Sb, and (ii) insertion of Sb into the remaining cobalt antimonide. • The mechanism of formation is qualitatively different from that responsible for the formation of the high pressure (greater than 20 GPa) phase. - Abstract: Polycrystalline samples of cobalt antimonide (CoSb2.79) were submitted to different conditions of pressure, temperature and processing time, in a high-pressure toroidal-type chamber, aiming to maximize the production of the high pressure phase previously observed in experiments with a diamond anvil cell. Rietveld refinements of X-ray powder diffraction data were performed to determine the phase composition and structural parameters. The maximum yield, 89(2) wt.% of SbxCoSb3−x phase, was obtained at 7.7 GPa, 550 °C and (at least) 5 min of processing time. The mechanism behind the formation of SbxCoSb3−x at high pressure and high temperature is actually not the same as that previously inferred from experiments at higher pressures (20 GPa) and room temperature with the diamond anvil cell. Indeed, evidences suggest that, at high pressure and high temperature, SbxCoSb3−x is formed by insertion of Sb resulting from decomposition of cobalt antimonide. Thermal conductivity, Seebeck coefficient and electrical conductivity were estimated for CoSb2.79 and Sb0.20CoSb2.80. The thermoelectric figure of merit at room temperature for Sb0.20CoSb2.80 resulted 33% greater than that for CoSb2.79

  12. High brightness electron sources

    International Nuclear Information System (INIS)

    High energy physics accelerators and free electron lasers put increased demands on the electron beam sources. This paper describes the present research on attaining intense bright electron beams using photoinjectors. Recent results from the experimental programs will be given. The performance advantages and difficulties presently faced by researchers will be discussed, and the following topics will be covered. Progress has been made in photocathode materials, both in lifetime and quantum efficiency. Cesium telluride has demonstrated significantly longer lifetimes than cesium antimonide at 10-8 torr. However, the laser system is more difficult because cesium telluride requires quadrupled YLF instead of the doubled YLF required for cesium antimonide. The difficulty in using photoinjectors is primarily the drive laser, in particular the amplitude stability. Finally, emittance measurements of photoinjector systems can be complicated by the non-thermal nature of the electron beam. An example of the difficulty in measuring beam emittance is given

  13. Electrochemical properties of CoFe3Sb12 as potential anode material for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    赵新兵; 钟耀东; 曹高劭

    2004-01-01

    A skutterudite-related antimonide, CoFe3Sb12,was prepared with vacuum melting.XRD analysis showed the material contained Sb, FeSb2, CoSb2 and CoSb3 phases.The electrochemical properties of the ball-milled CoFe3Sb12-10wt% graphite composite were studied using pure lithium as the reference electrode. A maximal lithium inserting capacity of about 860 mAh/g was obtained in the first cycle.The reversible capacity of the material was about 560mAh/g in the first cycle and decreased to ca.320 mAh/g and 250 mAh/g after 10 and 20 cycles respectively.Ex-situ XRD analyses showed that the antimonides in the pristine material were decomposed after the first discharge and that antimony was the active element for lithium to insert into the host material.

  14. Improved retrieval of gas abundances from near-infrared solar FTIR spectra measured at the Karlsruhe TCCON station

    OpenAIRE

    Kiel, M.; Wunch, D.; Wennberg, P. O.; Toon, G. C.; Hase, F.; Blumenstock, T.

    2016-01-01

    We present a modified retrieval strategy for solar absorption spectra recorded by the Karlsruhe Fourier Transform Infrared (FTIR) spectrometer, which is operational within the Total Carbon Column Observing Network (TCCON). In typical TCCON stations, the 3800–11 000 cm−1 spectral region is measured on a single extended Indium Gallium Arsenide (InGaAs) detector. The Karlsruhe setup instead splits the spectrum across an Indium Antimonide (InSb) and InGaAs detecto...

  15. Preparation of Al–Sb semiconductor by swift heavy ion irradiation

    Indian Academy of Sciences (India)

    R K Mangal; M Singh; Y K Vijay; D K Avasthi

    2006-12-01

    Al–Sb bilayer thin films having various thicknesses were deposited by thermal evaporation on ITO-coated conducting glass substrates at a pressure of 10-5 torr. These films were irradiated by Ag12+ heavy ions of energy, 160 MeV, with a fluence of 2.2 × 1013 ions/cm2, to get aluminum antimonide semiconductor. Rutherford back scattering and optical band gap data confirmed mixing of bilayer to form the semi-conducting system.

  16. Two dimensional metallic photonic crystals for light trapping and anti-reflective coatings in thermophotovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Shemelya, Corey; DeMeo, Dante F.; Vandervelde, Thomas E. [The Renewable Energy and Applied Photonics Laboratories, Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States)

    2014-01-13

    We report the development of a front-side contact design for thermophotovoltaics that utilizes metallic photonic crystals (PhCs). While this front-side grid replacement covers more surface area of the semiconductor, a higher percentage of photons is shown to be converted to usable power in the photodiode. This leads to a 30% increase in the short-circuit current of the gallium antimonide thermophotovoltaic cell.

  17. Coating Thermoelectric Devices To Suppress Sublimation

    Science.gov (United States)

    Sakamoto, Jeffrey; Caillat, Thierry; Fleurial, Jean-Pierre; Snyder, G. Jeffrey

    2007-01-01

    A technique for suppressing sublimation of key elements from skutterudite compounds in advanced thermoelectric devices has been demonstrated. The essence of the technique is to cover what would otherwise be the exposed skutterudite surface of such a device with a thin, continuous film of a chemically and physically compatible metal. Although similar to other sublimation-suppression techniques, this technique has been specifically tailored for application to skutterudite antimonides. The primary cause of deterioration of most thermoelectric materials is thermal decomposition or sublimation - one or more elements sublime from the hot side of a thermoelectric couple, changing the stoichiometry of the device. Examples of elements that sublime from their respective thermoelectric materials are Ge from SiGe, Te from Pb/Te, and now Sb from skutterudite antimonides. The skutterudite antimonides of primary interest are CoSb3 [electron-donor (n) type] and CeFe(3-x)Co(x)Sb12 [electron-acceptor (p) type]. When these compounds are subjected to typical operating conditions [temperature of 700 C and pressure niobium, which was selected for its chemical stability. In the experiment, the wrapped specimen was heated to a temperature of 700 C in a vacuum of residual pressure niobium foil prevented sublimation of antimony at 700 C. This was a considerable improvement, considering that uncoated CoSb3 had been found to decompose to form the lowest antimonide at the surface at only 600 C. Evidently, because the mean free path of Sb at the given temperature and pressure was of the order of tens of centimeters, any barrier closer than tens of centimeters (as was the niobium foil) would have suppressed transport of Sb vapor, thereby suppressing sublimation of Sb

  18. Performance of a Double Gate Nanoscale MOSFET (DG-MOSFET) Based on Novel Channel Materials

    OpenAIRE

    Rakesh Prasher; Devi Dass; Rakesh Vaid

    2013-01-01

    In this paper, we have studied a double gate nanoscale MOSFET for various channel materials using simulation approach. The device metrics considered at the nanometer scale are subthreshold swing (SS), drain induced barrier lowering (DIBL), on and off current, carrier injection velocity (vinj), etc. The channel materials studied are Silicon (Si), Germanium (Ge), Gallium Arsenide (GaAs), Zinc Oxide (ZnO), Zinc Sulfide (ZnS), Indium Arsenide (InAs), Indium Phosphide (InP) and Indium Antimonide (...

  19. La2NiSb. A ternary ordered version of the Bi3Ni type with highly polar bonding

    International Nuclear Information System (INIS)

    The lanthanum-rich antimonide La2NiSb was synthesized by annealing a cold-pressed pellet of the elements in a sealed silica glas tube at 1120 K. La2NiSb was characterized by powder and single-crystal X-ray diffraction: ordered Bi3Ni type, Pnma, Z = 4, a = 825.6(3), b = 452.2(2), c = 1195.5(4) pm, wR = 0.0695, 856 F2 values, 26 variables. The nickel atoms form infinite zig-zag chains (259 pm Ni-Ni) with trigonal-prismatic lanthanum coordination for each nickel atom. The antimony atoms cap the rectangular faces of the lanthanum prisms (336 pm La-Sb) and thereby coordinate also the nickel atoms (271 pm Ni-Sb). These rods run parallel to the b axis and form a herringbone pattern, similar to the FeB-type structure of GdNi. Although metallic conductivity is expected for La2NiSb from DFT-based band structure calculations, the real-space bonding analysis shows prominent localization of electrons on antimonide anions and positively charged lanthanum cations. The chain substructure is strongly bonded by polar covalent Ni-Sb and multicenter Ni-Ni interactions. The nickel atoms, which are involved in multicenter bonding with adjacent nickel and lanthanum atoms, provide a conductivity pathway along the prismatic strands. 121Sb Moessbauer spectroscopic data at 78 K show a single signal at an isomer shift of -7.62(3) mm s-1, supporting the antimonide character. La2NiSb shows weak paramagnetism with a susceptibility of 2.5 x 10-3 emu mol-1 at room temperature.

  20. TEM based analysis of III-Sb VECSELs on GaAs substrates for improved laser performance.

    Science.gov (United States)

    Ahirwar, P.; Shima, D.; Rotter, T. J.; Clark, S. P. R...; Addamane, S. J.; Hains, C. P.; Dawson, L. R.; Balakrishnan, G.; Bedford, R.; Lai, Y. Y.; Laurain, A.; Hader, J.; Moloney, J. V.

    2013-02-01

    The antimonide based vertical external cavity surface emitting lasers (VECSELs) operating in the 1.8 to 2.8 Tm wavelength range are typically based on InGaAsSb/AlGaAsSb quantum wells on AlAsSb/GaSb distributed Bragg reflectors (DBRs) grown lattice-matched on GaSb substrates. The ability to grow such antimonide VECSEL structures on GaAs substrates can take advantage of the superior AlAs based etch-stop layers and mature DBR technology based on GaAs substrates. The growth of such III-Sb VECSELs on GaAs substrates is non-trivial due to the 7.78% lattice mismatch between the antimonide based active region and the GaAs/AlGaAs DBR. The challenge is therefore to reduce the threading dislocation density in the active region without a very thick metamorphic buffer and this is achieved by inducing 90 ° interfacial mist dislocation arrays between the GaSb and GaAs layers. In this presentation we make use of cross section transmission electron microscopy to analyze a variety of approaches to designing and growing III-Sb VECSELs on GaAs substrates to achieve a low threading dislocation density. We shall demonstrate the failure mechanisms in such growths and we analyze the extent to which the threading dislocations are able to permeate a thick active region. Finally, we present growth strategies and supporting results showing low-defect density III-Sb VECSEL active regions on GaAs.

  1. Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

    Science.gov (United States)

    Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D., Jr.; Joslin, G.D.

    2008-01-01

    Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

  2. Influence of crystal–melt interface shape on self-seeding and single crystalline quality

    Indian Academy of Sciences (India)

    D B Gadkari; P Shashidharan; K B Lal; B M Arora

    2001-10-01

    The growth of Sb-based crystals (InSb, GaSb etc) was undertaken using resistive heater furnace by vertical directional solidification (VDS) technique. Crystal–melt interface shape during the growth was shown to convert from concave to convex along the crystal axis of the ingots. Many antimonide (Sb) crystals of 8 mm to 18 mm diameter were grown by optimized growth parameters. The forced convection and absence of conducting support to ampoule showed improvement in crystal quality of as grown ingots. Crystals showed preferred orientation and self-seeding. Results on interface shape and crystallinity of ingots were found to be in good agreement with the experiments.

  3. The National Optical Astronomy Observatories 1-5 micron imaging camera - a new national resource

    International Nuclear Information System (INIS)

    A liquid-cooled two-cryogen imaging camera for IR astronomy is examined. The camera is designed for use with a 58 x 62 indium antimonide photovoltaic hybrid array over the spectral range 1-5 microns. Two versions of the camera design are considered, one using reflective or transmissive optics, and the other using only transmissive optics. The mechanical, cryogenic, and optical design of the camera and the camera's mirror layouts and lens systems are described and illustrated. The observational performance of the camera is discussed and results are presented from astronomical studies using the camera

  4. Quartz-enhanced photoacoustic spectroscopy sensor for ethylene detection with a 3.32 μm distributed feedback laser diode

    International Nuclear Information System (INIS)

    An antimonide distributed feedback quantum wells diode laser operating at 3.32 μm at near room temperature in the continuous wave regime has been used to perform ethylene detection based on quartz enhanced photoacoustic spectroscopy. An absorption line centered at 3007.52 cm−1 was investigated and a normalized noise equivalent absorption coefficient (1σ) of 3.09 10−7 cm−1 W Hz−1/2 was obtained. The linearity and the stability of the detection have been evaluated. Biological samples’ respiration has been measured to validate the feasibility of the detection setup in an agronomic environment, especially on ripening apples

  5. Design and fabrication of 6.1-.ANG. family semiconductor devices using semi-insulating A1Sb substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sherohman, John W. (Livermore, CA); Coombs, III, Arthur W. (Patterson, CA); Yee, Jick Hong (Livermore, CA); Wu, Kuang Jen J. (Cupertino, CA)

    2007-05-29

    For the first time, an aluminum antimonide (AlSb) single crystal substrate is utilized to lattice-match to overlying semiconductor layers. The AlSb substrate establishes a new design and fabrication approach to construct high-speed, low-power electronic devices while establishing inter-device isolation. Such lattice matching between the substrate and overlying semiconductor layers minimizes the formation of defects, such as threaded dislocations, which can decrease the production yield and operational life-time of 6.1-.ANG. family heterostructure devices.

  6. Simulation and Finite Element Analysis of Electrical Characteristics of Gate-all-Around Junctionless Nanowire Transistors

    Directory of Open Access Journals (Sweden)

    Neel Chatterjee

    2016-03-01

    Full Text Available Gate all around nanowire transistors is one of the widely researched semiconductor devices, which has shown possibility of further miniaturization of semiconductor devices. This structure promises better current controllability and also lowers power consumption. In this paper, Silicon and Indium Antimonide based nanowire transistors have been designed and simulated using Multiphysics simulation software to investigate on its electrical properties. Simulations have been carried out to study band bending, drain current and current density inside the device for changing gate voltages. Further analytical model of the device is developed to explain the physical mechanism behind the operation of the device to support the simulation result.

  7. Ultralow Resistance Ohmic Contacts for p-Channel InGaSb Field-Effect Transistors

    OpenAIRE

    Guo, Luke W.; Brian R. Bennett; Boos, John Brad; Lu, Wenjie; del Alamo, Jesus A.

    2015-01-01

    We demonstrate ultralow ohmic contact resistance to antimonide-based, p-channel quantum-well field-effect transistor (QW-FET) structures using a new p[superscript ±]-InAs/InAsSb cap structure. The incorporation of a p[superscript ±]-InAsSb layer enables the use of a thicker cap with lower sheet resistance, resulting in an improved contact resistivity. Using a Pd-based ohmic scheme, the composite cap structure resulted in a 4x reduction in contact resistance compared with a standard p[superscr...

  8. Mn-doped Ga(As,P) and (Al,Ga)As ferromagnetic semiconductors

    OpenAIRE

    J. Masek; Kudrnovsky, J.; Maca, F.; Sinova, Jairo; MacDonald, A. H.; Campion, R. P.; Gallagher, B.L.; Jungwirth, T.

    2006-01-01

    A remarkable progress towards functional ferromagnetic semiconductor materials for spintronics has been achieved in p-type (Ga,Mn)As. Robust hole-mediated ferromagnetism has, however, been observed also in other III-V hosts such as antimonides, GaP or (Al,Ga)As which opens a wide area of possibilities for optimizing the host composition towards higher ferromagnetic Curie temperatures. Here we explore theoretically ferromagnetism and Mn incorporation in Ga(As,P) and (Al,Ga)As ternary hosts. Wh...

  9. Photometric Error Analysis. IX: Optimum Use of Photomultipliers.

    Science.gov (United States)

    Young, A T

    1969-12-01

    A critical study of photomultipliers leads to the following conclusions: (1) the dark current observed in tubes with alkali-antimonide cathodes at room temperature is primarily due to gas ions, not thermionic emission; (2) deviation from idealized (simple Poisson) pulse-height distributions is primarily due to secondary electron loss, particularly in venetian blind multipliers; (3) pulse-counting provides better signal-to-noise ratio than any other simple detection scheme, and is not far from optimum detection in most cases. However, dc methods can approach pulse-counting quite closely if digital readout is used. A convenient method for determining optimum discriminator levels is presented, with examples. PMID:20076054

  10. Status of SAT CID InSb detector technology and applications

    International Nuclear Information System (INIS)

    This paper presents SAT indium antimonide Charge Injection Devices (C.I.D) Technology, post focal plane signal processing and some applications. These detectors are constituted by MOS capacitors realized on InSb wafers using integrated circuit-like processing. When a negative voltage is applied to the structure (put it into depletion) the capacitors form integrating detectors for use in 3-5 μm band. Linear arrays constituted by a line of single capacitors, matrix arrays constituted by a group of two coupled MOS capacitors, collect and store photon generated charge carriers. In the last case, the selection of a site is accomplished by X-Y decoding technique

  11. Skylab experiments on semiconductors and alkali halides. [single crystal growth

    Science.gov (United States)

    Lundquist, C. A.

    1974-01-01

    The space processing experiments performed during the Skylab missions included one on single crystal growth of germanium selenide and telluride, one on pure and doped germanium crystals, two on pure and doped indium antimonide, one on gallium-indium-antimony systems, and one on a sodium chloride-sodium fluoride eutectic. In each experiment, three ampoules of sample were processed in the multipurpose electric furnace within the Skylab Materials Processing Facility. All were successful in varying degrees and gave important information about crystal growth removed from the effects of earth surface gravity.

  12. Measurement of de Haas-van Alphen Effect with Hybrid Magnet(Transport and Fermiology)

    OpenAIRE

    Kido, Giyuu; Nimori, Shigeki; Nakagawa, Yasuaki

    1993-01-01

    An apparatus to measure the de Haas-van Alphen effect in steady high magnetic field has been constructed by using hybrid magnets at Tohoku University. Fermi surfaces were investigated on cuprate high-temperature superconductor and rare earth antimonide. The spectral analyses were performed by using the maximum entropy method as well as the Fourier transformation. In magnetically oriented YBa_2Cu_3O_ and Tl_2Ba_2CuO_ powder , the spectral density shows a peak at 456 T and 400 T, respectively. ...

  13. Performance analysis of InSb based QWFET for ultra high speed applications

    International Nuclear Information System (INIS)

    An indium antimonide based QWFET (quantum well field effect transistor) with the gate length down to 50 nm has been designed and investigated for the first time for L-band radar applications at 230 GHz. QWFETs are designed at the high performance node of the International Technology Road Map for Semiconductors (ITRS) requirements of drive current (Semiconductor Industry Association 2010). The performance of the device is investigated using the SYNOPSYS CAD (TCAD) software. InSb based QWFET could be a promising device technology for very low power and ultra-high speed performance with 5–10 times low DC power dissipation. (semiconductor devices)

  14. Final Report, Photocathodes for High Repetition Rate Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook University

    2014-04-20

    This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus is on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-antimonide cathodes b) Development and testing of a diamond amplifier for photocathodes c) Tests of both cathodes in superconducting RF photoguns and copper RF photoguns

  15. Photocathode aging in MCP PMT

    International Nuclear Information System (INIS)

    We study aging of alkali-antimonide photocathodes in the microchannel plate photomultiplier tubes (MCP PMT) manufactured in Novosibirsk by ''Ekran FEP'' company. Such PMTs are used in the particle identification systems of KEDR, SND and CMD-3 experiments carried out at e+e− colliders VEPP-4M and VEPP-2000 in the Budker Institute of Nuclear Physics. The quantum efficiency (QE) degradation of a PMT equipped with MCP Chevron has been measured at different photon counting rates from 4⋅107 to 6⋅1010 s−1cm−2. It is found that the QE decrease is proportional to the charge extracted from the MCP nearest to the photocathode rather than to the output charge. The comparison of different types of alkali-antimonide photocathodes has shown that the treatment of photocathode with vapors of cesium and antimony can dramatically reduce the photocathode aging rate. The photocathode lifetime of the best MCP PMT sample has been measured at the photon counting rate of 107 cm−2s−1 and the initial gain of 106. The peak quantum efficiency degraded by 20% after accumulation of 3.3 C/cm2 anode charge.

  16. Debye screening length effects of nanostructured materials

    CERN Document Server

    Ghatak, Kamakhya Prasad

    2014-01-01

    This monograph solely investigates the Debye Screening Length (DSL) in semiconductors and their nano-structures. The materials considered are quantized structures of non-linear optical, III-V, II-VI, Ge, Te, Platinum Antimonide, stressed materials, Bismuth, GaP, Gallium Antimonide, II-V and Bismuth Telluride respectively. The DSL in opto-electronic materials and their quantum confined counterparts is studied in the presence of strong light waves and intense electric fields on the basis of newly formulated electron dispersion laws that control the studies of such quantum effect devices. The suggestions for the experimental determination of 2D and 3D DSL and the importance of measurement of band gap in optoelectronic materials under intense built-in electric field in nano devices and strong external photo excitation (for measuring photon induced physical properties) have also been discussed in this context. The influence of crossed electric and quantizing magnetic fields on the DSL and the DSL in heavily doped ...

  17. Einstein's photoemission emission from heavily-doped quantized structures

    CERN Document Server

    Ghatak, Kamakhya Prasad

    2015-01-01

    This monograph solely investigates the Einstein's Photoemission(EP) from Heavily Doped(HD) Quantized Structures on the basis of newly formulated electron dispersion laws. The materials considered are quantized structures of HD non-linear optical, III-V, II-VI, Ge, Te, Platinum Antimonide, stressed materials, GaP, Gallium Antimonide, II-V, Bismuth Telluride together with various types of HD superlattices and their Quantized counterparts respectively. The EP in HD opto-electronic materials and their nanostructures is studied in the presence of strong light waves and intense electric fields  that control the studies of such quantum effect devices. The suggestions for the experimental determinations of different important physical quantities in HD 2D and 3D materials  and the importance of measurement of band gap in HD optoelectronic materials under intense built-in electric field in nano devices and strong external photo excitation (for measuring   physical properties in the presence of intense light waves w...

  18. Heavily-doped 2D-quantized structures and the Einstein relation

    CERN Document Server

    Ghatak, Kamakhya P

    2015-01-01

    This book presents the Einstein Relation(ER) in two-dimensional (2-D) Heavily Doped(HD) Quantized Structures. The materials considered are quantized structures of HD non-linear optical, III-V, II-VI, Ge, Te, Platinum Antimonide, stressed materials, GaP, Gallium Antimonide, II-V, Bismuth Telluride together with various types of HD superlattices and their Quantized counterparts respectively. The ER in HD opto-electronic materials and their nanostructures is studied in the presence of strong light waves and intense electric fields on the basis of newly formulated electron dispersion laws that control the studies of such quantum effect devices. The suggestion for the experimental determination of HD 2D and 3D ERs and the importance of measurement of band gap in HD optoelectronic materials under intense built-in electric field in nanodevices and strong external photo excitation (for measuring photon induced physical properties) are also discussed in this context. The influence of crossed electric and quantizing ma...

  19. Photocathodes inside superconducting cavities. Studies on the feasibility of a superconducting photoelectron source of high brightness. External report

    International Nuclear Information System (INIS)

    We have done studies and experiments to explore the feasibility of a photoemission RF gun with a superconducting accelerator cavity. This concept promises to provide an electron beam of high brightness in continuous operation. It is thus of strong interest for a free-electron-laser or a linear collider based on a superconducting accelerator. In a first step we studied possible technical solutions for its components, especially the material of the photocathode and the geometrical shape of the cavity. Based on these considerations, we developed the complete design for a prototype electron source. The cathode material was chosen to be alkali antimonide. In spite of its sensitivity, it seems to be the best choice for a gun with high average current due to its high quantum efficiency. The cavity shape was at first a reentrant-type single cell of 500 MHz. It is now replaced by a more regular two-and-half cell shape, an independent half cell added for emittance correction. Its beam dynamics properties are investigated by numerical simulations; we estimated a beam brightness of about 5x1011 A/(m.rad)2. But the mutual interactions between alkali antimonide photocathode and superconducting cavity must be investigated experimentally, because they are completely unkown. (orig.)

  20. Design optimization of superlattice type-II IR-detection modules with temporal signal coincidence in two spectral ranges

    Science.gov (United States)

    Breiter, R.; Lutz, H.; Scheibner, R.; Wendler, J.; Hofmann, K.; Ziegler, J.; Walther, M.; Rehm, R.

    2008-04-01

    3rd Generation IR detectors providing e.g. dual-color capability are of great benefit for applications like aircraft missile approach warning systems using this feature for achieving low false alarm rates by separating the hot CO2 missile plume from background and clutter. AIM and IAF selected antimonide based type II Superlattices (SL) for such kind of applications. The type II SL technology provides an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. IAF and AIM already managed to realize a dual-color 384x288 IR-Module based on this technology. It combines spectral selective detection in the 3-4 μm wavelength range and 4-5 μm wavelength range in each pixel with coincident integration in a 384x288x2 format and 40 μm pitch. Excellent thermal resolution with NETD crosstalk between the two colors the layer thickness of the SL-layer was optimized. This paper is intended to present the current status and trends at AIM on antimonide type II Superlattices (SL) IR module developments for ground and airborne applications in the high performance range, where rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - require temporal signal coincidence with integration times of typically 1ms.

  1. Magnetic properties of RE{sub 3}Pd{sub 6}Sb{sub 5} (RE = Pr, Nd, Gd) and a group-subgroup scheme for Ce{sub 3}Pd{sub 6}Sb{sub 5} and Yb{sub 5}Cu{sub 11}Sn{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, Inga; Hoffmann, Rolf-Dieter; Seidel, Stefan; Schwickert, Christian; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2011-10-15

    The Ce3Pd6Sb5-type antimonides RE{sub 3}Pd{sub 6}Sb{sub 5} (RE = Pr, Nd, Sm, Gd, Tb) were synthesized by arc-melting and subsequent annealing in sealed silica ampoules in a high-frequency furnace. The new compounds Sm{sub 3}Pd{sub 6}Sb{sub 5} (a = 1337.0(5), b = 441.5(1), c = 988.6(3) pm) and Tb{sub 3}Pd{sub 6}Sb{sub 5} (a = 1328.8(4), b = 439.9(2), c = 976.6(5) pm) were characterized by powder X-ray diffraction data. The RE{sub 3}Pd{sub 6}Sb{sub 5} antimonides adopt an ordered defect structure that derives from the CaBe{sub 2}Ge{sub 2} type. Their crystal chemistry is compared to the structures of Ce{sub 8}Rh{sub 17}Sb{sub 14} and Yb{sub 5}Cu{sub 11}Sn{sub 8} on the basis of group-subgroup schemes. Temperature-dependent magnetic susceptibility data of the samples with RE = Pr, Nd and Gd show Curie-Weiss paramagnetism of the trivalent rare earths. Low-field susceptibility measurements reveal magnetic ordering at low temperatures. (orig.)

  2. Study of the influence of semiconductor material parameters on acoustic wave propagation modes in GaSb/AlSb bi-layered structures by Legendre polynomial method

    Science.gov (United States)

    Othmani, Cherif; Takali, Farid; Njeh, Anouar; Ben Ghozlen, Mohamed Hédi

    2016-09-01

    The propagation of Rayleigh-Lamb waves in bi-layered structures is studied. For this purpose, an extension of the Legendre polynomial (LP) method is proposed to formulate the acoustic wave equation in the bi-layered structures induced by thin film Gallium Antimonide (GaSb) and with Aluminum Antimonide (AlSb) substrate in moderate thickness. Acoustic modes propagating along a bi-layer plate are shown to be quite different than classical Lamb modes, contrary to most of the multilayered structures. The validation of the LP method is illustrated by a comparison between the associated numerical results and those obtained using the ordinary differential equation (ODE) method. The convergency of the LP method is discussed through a numerical example. Moreover, the influences of thin film GaSb parameters on the characteristics Rayleigh-Lamb waves propagation has been studied in detail. Finally, the advantages of the Legendre polynomial (LP) method to analyze the multilayered structures are described. All the developments performed in this work were implemented in Matlab software.

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

    Science.gov (United States)

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

    2013-07-01

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

  4. Some aspects of detection in the low temperatures diode detectors

    International Nuclear Information System (INIS)

    Diode detectors (DD) are widely used in electronic information and communication systems. The numerical modeling of the electrical properties in the contacts of the high temperature superconductor (HTSC) with semiconductor indium antimonide (InSb) had been made. There were analyzed the possibilities to create DD based on these contacts and working at liquid nitrogen temperature 77.4 K. The influence of the contact potential difference on the DD parameters was analyzed. Also the numerical modeling of the electrical potential distribution and current passing in the contacts of normal metal or superconductor with semiconductor alloy bismuth-antimony (Bi-Sb) was made. There were analyzed possibilities to create DD based on these contacts and working at liquid helium temperature 4.2 K. The comparison with existent literature data shows the proposed DD can be 10-100 times better. Therefore these DD are perspective for cryogenic electronics and there is an actual problem to elaborate them. (authors)

  5. Design and Simulated Characteristics of Nanosized InSb Based Heterostructure Devices

    Directory of Open Access Journals (Sweden)

    T. D. Subash

    2014-01-01

    Full Text Available Indium antimonide nanoparticles were synthesized at room temperature. X-ray diffraction measurements are utilized to characterize the nanocomposites. The InSb nanoparticle has an average particle size in a range of 47 mm to 99 mm which is observed using the XRD result. The InSb is a material which is used to design the transistor. For designing purpose the simulator TCAD is used, by which the HEMT device is structured and its performance is analyzed and it is found that transistor operates as normal devices. This designed device is more valuable since a nanocomposite InSb material is used as a channel in HEMT device, thereby leading to the nanosized HEMT device. In addition, InSb has the property of high saturation velocity and mobility which results in higher performance of the device than any other materials in III-V compounds.

  6. Lattice thermal conductivity of filled skutterudites: An anharmonicity perspective

    International Nuclear Information System (INIS)

    We report a phenomenological model to calculate the high-temperature lattice thermal conductivity of filled skutterudite antimonides. The model needs no phonon resonant scattering terms. Instead, we assume that umklapp processes dominate the high-temperature phonon scattering. In order to represent the anharmonicity introduced by the filling atom, we introduce a Gaussian term into the relaxation time of the umklapp process. The developed model agrees remarkably well with the experimental results of REfCo4Sb12 and REfFe4Sb12 (RE = Yb, Ba, and Ca) alloys. To further test the validity of our model, we calculate the lattice thermal conductivity of nanostructured or multi-filled skutterudites. The calculation results are also in good agreement with experiment, increasing our confidence in the developed anharmonicity model.

  7. Diffusion of impurities and the formation of structural defects in narrow-gap semiconductors by intensive light pulses

    International Nuclear Information System (INIS)

    Introduction of impurity from metal films into the near surface layer of indium antimonide and lead-tin chalcogenide monocrystals under pulsed light irradiation for the purpose of formation of photosensitive p-n transition is investigated. Peculiar features of photostimulated diffusion in the mentioned semiconductors are discussed. The depth of the melted layer during the light pulse action is calculated. An inversion layer on the metallized InSh surface at 0.7 Jxcm-2 irradiation energy density and in lead-tin telluride and selenide monocrystals with copper film at 0.5 Jxcm-2 for 100 ns duration is obtained. The effect of the light pulse power on the photosensitivity and rectification factor of the narrow-band semiconductor diode structures is investigated

  8. Quartz-enhanced photoacoustic spectroscopy sensor for ethylene detection with a 3.32 μm distributed feedback laser diode

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Ba, T.; Triki, M.; Vicet, A., E-mail: a.vicet@univ-montp2.fr [Université de Montpellier, IES, UMR 5214, F-34000 Montpellier (France); CNRS, IES, UMR 5214, F-34000 Montpellier (France); Desbrosses, G. [LSTM, UMR 113, IRD, CIRAD, UM2, SupAgro, Université Montpellier 2, Place E. Baaillon, F-34095 Montpellier (France)

    2015-02-15

    An antimonide distributed feedback quantum wells diode laser operating at 3.32 μm at near room temperature in the continuous wave regime has been used to perform ethylene detection based on quartz enhanced photoacoustic spectroscopy. An absorption line centered at 3007.52 cm{sup −1} was investigated and a normalized noise equivalent absorption coefficient (1σ) of 3.09 10{sup −7} cm{sup −1} W Hz{sup −1/2} was obtained. The linearity and the stability of the detection have been evaluated. Biological samples’ respiration has been measured to validate the feasibility of the detection setup in an agronomic environment, especially on ripening apples.

  9. Thermodynamics of (Ga, In)-Sb-O-Si and impact on dewetting process

    Energy Technology Data Exchange (ETDEWEB)

    Sylla, L. [Cyberstar, Echirolles (France); Duffar, T. [SIMaP-EPM, Saint Martin d' Heres (France)

    2011-11-15

    A thermodynamic study is performed for the systems (Ga or In)-Sb-O-Si in order to better understand the difference observed during dewetting experiments of GaSb and InSb in silica ampoules. Results show that the melts can be considered as non reactive toward silica. When the atmosphere is clean ({<=}1 ppm O{sub 2}), no oxide is formed, while, under oxidising atmosphere, oxides exist above the melting point of the antimonide and are known to increase the wetting angle of the melt on the crucible. However the temperature range for oxide stability is smaller in the case of InSb and this may explain why dewetting is easy for GaSb in presence of oxygen, while it is difficult for InSb. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Growth of GaSb single crystals by an improved dewetting process

    Science.gov (United States)

    Duffar, Th.; Dusserre, P.; Giacometti, N.

    2001-02-01

    Gallium antimonide single crystals have been grown in silica tubes by the modified vertical Bridgman process. This method uses the dewetting phenomenon (Duffar et al., J. Crystal Growth 211 (2000) 434) and avoids crystal-crucible contact by the application of a gas pressure opposing the hydrostatic pressure of the molten sample. It is shown that the process and crystal quality are very sensitive to traces of oxygen in the gas circuit. In order to avoid this problem, and to solve some potential drawbacks of the method, a simplified variant is proposed where the pressure is adjusted by heating an inert gas volume. It is shown experimentally that this new process is self-controlled in terms of pressure adjustment.

  11. Study of bi-alkali photocathode growth on glass by X-ray techniques for fast timing response photomultipliers

    Science.gov (United States)

    Xie, Junqi; Demarteau, Marcel; Wagner, Robert; Ruiz-Oses, Miguel; Liang, Xue; Ben-Zvi, Ilan; Attenkofer, Klaus; Schubert, Susanne; Smedley, John; Wong, Jared; Padmore, Howard; Woll, Arthur

    2014-03-01

    Bi-alkali antimonide photocathode is an essential component in fast timing response photomultipliers. Real-time in-situ grazing incidence x-ray diffraction and post-growth x-ray reflectivity measurement were performed to study the photocathode deposition process on glass substrate. Grazing incidence x-ray diffraction patterns show the formation of Sb crystalline, dissolution of crystalline phase Sb by the application of K vapor and reformation of refined crystal textures. XRR result exhibits that the film thickness increases ~ 4.5 times after K diffusion and almost have no change after Cs diffusion. Further investigation is expected to understand the photocathode growth process and provide guidelines for photocathode development.

  12. Innovation in crystal growth: A personal perspective

    Science.gov (United States)

    Mullin, J. B.

    2008-04-01

    The evolution of crystal growth has been crucially dependent on revolutionary innovations and initiatives involving ideas, technology and communication. A personal perspective is presented on some of these aspects in connection with the early history of semiconductors that have helped evolve our knowledge and advance the science and technology of crystal growth. The presentation considers examples from work on germanium, silicon, indium antimonide, gallium arsenide, indium phosphide, gallium phosphide and mercury cadmium telluride. In connection with metal organic vapour phase epitaxy (MOVPE), the influence of adduct purification for alkyls is noted together with the growth of Hg xCd 1-xTe. The role of crystal growth organisations together with initiatives in the publication of the Journal of Crystal Growth (JCG) and the pivotal role of the International Organisation of Crystal Growth (IOCG) are also highlighted in the quest for scientific excellence.

  13. Nanomaterials for Electronics and Optoelectronics

    Science.gov (United States)

    Koehne, Jessica E.; Meyyappan, M.

    2011-01-01

    Nanomaterials such as carbon nanotubes(CNTs), graphene, and inorganic nanowires(INWs) have shown interesting electronic, mechanical, optical, thermal, and other properties and therefore have been pursued for a variety of applications by the nanotechnology community ranging from electronics to nanocomposites. While the first two are carbon-based materials, the INWs in the literature include silicon, germanium, III-V, II-VI, a variety of oxides, nitrides, antimonides and others. In this talk, first an overview of growth of these three classes of materials by CVD and PECVD will be presented along with results from characterization. Then applications in development of chemical sensors, biosensors, energy storage devices and novel memory architectures will be discussed.

  14. Ultrasensitive detection of nitric oxide at 5.33 μm by using external cavity quantum cascade laser-based Faraday rotation spectroscopy

    Science.gov (United States)

    Lewicki, Rafał; Doty, James H.; Curl, Robert F.; Tittel, Frank K.; Wysocki, Gerard

    2009-01-01

    A transportable prototype Faraday rotation spectroscopic system based on a tunable external cavity quantum cascade laser has been developed for ultrasensitive detection of nitric oxide (NO). A broadly tunable laser source allows targeting the optimum Q3/2(3/2) molecular transition at 1875.81 cm−1 of the NO fundamental band. For an active optical path of 44 cm and 1-s lock-in time constant minimum NO detection limits (1σ) of 4.3 parts per billion by volume (ppbv) and 0.38 ppbv are obtained by using a thermoelectrically cooled mercury–cadmium–telluride photodetector and liquid nitrogen-cooled indium–antimonide photodetector, respectively. Laboratory performance evaluation and results of continuous, unattended monitoring of atmospheric NO concentration levels are reported. PMID:19625625

  15. R(Au∼0.75Sb∼0.25)2 (R = La, Ce, Pr) with UHg2 structure type, new members of the AlB2 family

    International Nuclear Information System (INIS)

    The crystal structure of a new series of ternary rare-earth gold antimonides R(Au∼0.75Sb∼0.25)2 (R = La, Ce, Pr) has been studied by X-ray powder diffraction from the 'as-cast' alloys. The hexagonal UHg2 structure type, a deformation derivative of AlB2 structure type, space group P6/mmm (No. 191), has been found for all compounds. Rietveld refinements for all three compounds were performed. The coordination polyhedron of R atom is hexagonal prism formed by 12 atoms of X (statistical mixture of Au and Sb atoms) with 2 additional atoms of R against base faces: [RX12R2]. The coordination polyhedron of statistical mixture X has the shape of full-capped trigonal prism [XR6X3X2

  16. Visible and infrared linear detector arrays for the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

    International Nuclear Information System (INIS)

    The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) instrument uses four separate focal plane assemblies consisting of line array detectors that are multiplexed to a common J-FET preamp using a FET switch multiplexing (MUX) technique. A 32-element silicon line array covers the spectral range from 0.41 to 0.70 microns. Three additional 64-element indium antimonide (InSb) line arrays cover the spectral range from 0.68 to 2.45 microns. The spectral sampling interval per detector element is nominally 9.8 nm, giving a total of 224 spectral channels. All focal planes operate at liquid nitrogen temperature and are housed in separate dewars. Electrical performance characteristics include a read noise of less than 1000 e(-) in all channels, response and dark nonuniformity of 5 percent peak to peak, and quantum efficiency of greater than 60 percent

  17. Low-noise discrete preamplifiers for InSb IR detectors

    International Nuclear Information System (INIS)

    For many application, for example, in ground-based astronomy, detector systems using small arrays or small numbers of discrete IR detectors are very useful. In particular, systems using indium antimonide (InSb) detectors are approaching background-limited performance throughout most of their useful wavelength band. The general requirements of preamplifiers for background-limited performance of InSb IR detector systems are presented. These amplifiers require a cryogenic Field-effect transistor (FET) first stage to achieve this level of performance. The electrical and thermal design tradeoffs of such amplifiers (TIAs) is estimated from a noise model. Measurements of noise voltage and noise current versus temperature are presented for a sample of commercially available junction FETs (JFETs)

  18. On the magnetic and Moessbauer spectroscopic characterization of EuPd{sub 2}Sb{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, Inga; Eul, Matthias; Poettgen, Rainer [Inst. fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Univ. Muenster (Germany)

    2010-01-15

    The CaBe{sub 2}Ge{sub 2}-type antimonide EuPd{sub 2}Sb{sub 2} (P4/nmm, a = 462.43(7), c = 1056.1(2) pm) was synthesized by induction melting of the elements in a sealed tantalum tube. Temperature-dependent magnetic susceptibility measurements have revealed Curie-Weiss behavior with an experimental magnetic moment of 7.93(1) {mu}{sub B}/Eu atom, indicating stable divalent europium. EuPd{sub 2}Sb{sub 2} orders antiferromagnetically at T{sub N} = 4.5(2) K as is also evident from almost full hyperfine field splitting (B{sub h} = 19.5 T) in the {sup 151}Eu Moessbauer spectrum at 4.2 K. (orig.)

  19. Magnetic studies on a new series of compounds RRh2Sb2 (R=La, Ce, Pr and Nd)

    International Nuclear Information System (INIS)

    We report the magnetic properties of a new ternary phase of antimonides, having the composition RRh2Sb2 (R=La, Ce, Pr and Nd) which have been found to crystallize in the tetragonal structure. Magnetic susceptibility of LaRh2Sb2 shows a peak at around 30 K. No magnetic ordering is seen down to 2 K in the other RRh2Sb2 compounds with R=Ce, Pr and Nd. The susceptibility of all of them largely follows the Curie-Weiss behaviour. The electrical resistivity of all these compounds is typical of metallic systems. No superconductivity is observed down to 2 K in any of these compounds. (orig.)

  20. High performance infrared fast cooled detectors for missile applications

    Science.gov (United States)

    Reibel, Yann; Espuno, Laurent; Taalat, Rachid; Sultan, Ahmad; Cassaigne, Pierre; Matallah, Noura

    2016-05-01

    SOFRADIR was selected in the late 90's for the production of 320×256 MW detectors for major European missile programs. This experience has established our company as a key player in the field of missile programs. SOFRADIR has since developed a vast portfolio of lightweight, compact and high performance JT-based solutions for missiles. ALTAN is a 384x288 Mid Wave infrared detector with 15μm pixel pitch, and is offered in a miniature ultra-fast Joule- Thomson cooled Dewar. Since Sofradir offers both Indium Antimonide (InSb) and Mercury Cadmium Telluride technologies (MCT), we are able to deliver the detectors best suited to customers' needs. In this paper we are discussing different figures of merit for very compact and innovative JT-cooled detectors and are highlighting the challenges for infrared detection technologies.

  1. Development of a long wavelength spectrometer for the 24-channel multispectral scanner: Instructions for installation, start-up, and adjustment

    Science.gov (United States)

    1974-01-01

    The basic information is presented, which is required for start-up and operation of two long-wavelength focal-plane and cooler assemblies, including the amplifiers and temperature control systems. The focal plane systems, referred to as the long wavelength spectrometer (LWS) were developed for direct replacement of Arrays 3 and 4 into the multispectral scanner presently being operated by the NASA Manned Spacecraft Center Facility, and Laboratory Support Branch. The equipment is comprised of two major sub-assemblies: Array 3 with three indium antimonide detector channels and Array 4 with seven mercury doped Germanium detector channels. Each array is mounted on a cryogenic cooler and includes the vacuum housings, mounting hardware (x, y, z translation and rotation stages) and detector signal conditioning, temperature control and monitoring electronics. The two arrays were designed to operate independently and do not share common equipment (viz power supplies, housings, mounts, etc.).

  2. Metallization for Yb14MnSb11-Based Thermoelectric Materials

    Science.gov (United States)

    Firdosy, Samad; Li, Billy Chun-Yip; Ravi, Vilupanur; Sakamoto, Jeffrey; Caillat, Thierry; Ewell, Richard C.; Brandon, Erik J.

    2011-01-01

    Thermoelectric materials provide a means for converting heat into electrical power using a fully solid-state device. Power-generating devices (which include individual couples as well as multicouple modules) require the use of ntype and p-type thermoelectric materials, typically comprising highly doped narrow band-gap semiconductors which are connected to a heat collector and electrodes. To achieve greater device efficiency and greater specific power will require using new thermoelectric materials, in more complex combinations. One such material is the p-type compound semiconductor Yb14MnSb11 (YMS), which has been demonstrated to have one of the highest ZT values at 1,000 C, the desired operational temperature of many space-based radioisotope thermoelectric generators (RTGs). Despite the favorable attributes of the bulk YMS material, it must ultimately be incorporated into a power-generating device using a suitable joining technology. Typically, processes such as diffusion bonding and/or brazing are used to join thermoelectric materials to the heat collector and electrodes, with the goal of providing a stable, ohmic contact with high thermal conductivity at the required operating temperature. Since YMS is an inorganic compound featuring chemical bonds with a mixture of covalent and ionic character, simple metallurgical diffusion bonding is difficult to implement. Furthermore, the Sb within YMS readily reacts with most metals to form antimonide compounds with a wide range of stoichiometries. Although choosing metals that react to form high-melting-point antimonides could be employed to form a stable reaction bond, it is difficult to limit the reactivity of Sb in YMS such that the electrode is not completely consumed at an operating temperature of 1,000 C. Previous attempts to form suitable metallization layers resulted in poor bonding, complete consumption of the metallization layer or fracture within the YMS thermoelement (or leg).

  3. Multispectral IR detection modules and applications

    Science.gov (United States)

    Münzberg, M.; Breiter, R.; Cabanski, W.; Lutz, H.; Wendler, J.; Ziegler, J.; Rehm, R.; Walther, M.

    2006-05-01

    This paper is intended to present firstly the current status at AIM on quantum well (QWIP) and antimonide superlattices (SL) detection modules for multi spectral ground and airborne applications in the high performance range i.e. for missile approach warning systems and secondly presents possibilities with long linear arrays i.e. 576x7 MCT to measure spectral selective in the 2 - 11μm wavelength range. QWIP and antimonide based superlattice (SL) modules are developed and produced in a work share between AIM and the Fraunhofer Institute for Applied Solid State Physics (IAF). The sensitive layers are manufactured by the IAF, hybridized and integrated to IDCA or camera level by AIM. In case of MCT based modules, all steps are done by AIM. QWIP dual band or dual color detectors provide good resolution as long as integration times in the order of 5-10ms can be tolerated. This is acceptable for all applications where no fast motions of the platform or the targets are to be expected. For spectral selective detection, a QWIP detector combining 3-5 μm (MWIR) and 8-10 μm (LWIR) detection in each pixel with coincident integration has been developed in a 384x288x2 format with 40 μm pitch. Excellent thermal resolution with NETD crosstalk in the array usually observed in QWIP arrays resulting in low MTF values was suppressed resulting in sharp image impression. For rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - a material system with higher quantum efficiency is required to limit integration times to typically 1ms. AIM and IAF selected antimonide based type II superlattices (SL) for such kind of applications. The type II SL technology provides - similar to QWIPs - an accurate engineering of sensitive layers by MBE with very good homogeneity and potentially good yield and resistivity against high temperature application i.e. under processing or storage. While promising results on single SL pixels have been reported since

  4. Ab initio study of the unusual thermal transport properties of boron arsenide and related materials

    Science.gov (United States)

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

    2013-12-01

    Recently, using a first principles approach, we predicted that zinc blende boron arsenide (BAs) will have an ultrahigh lattice thermal conductivity, κ, of over 2000 Wm-1K-1 at room temperature (RT), comparable to that of diamond. Here, we provide a detailed ab initio examination of phonon thermal transport in boron arsenide, contrasting its unconventional behavior with that of other related materials, including the zinc blende crystals boron nitride (BN), boron phosphide, boron antimonide, and gallium nitride (GaN). The unusual vibrational properties of BAs contribute to its weak phonon-phonon scattering and phonon-isotope scattering, which are responsible for its exceptionally high κ. The thermal conductivity of BAs has contributions from phonons with anomalously large mean free paths (˜2 μm), two to three times those of diamond and BN. This makes κ in BAs sensitive to phonon scattering from crystal boundaries. An order of magnitude smaller RT thermal conductivity in a similar material, zinc blende GaN, is connected to more separated acoustic phonon branches, larger anharmonic force constants, and a large isotope mixture on the heavy rather than the light constituent atom. The striking difference in κ for BAs and GaN demonstrates the importance of using a microscopic first principles thermal transport approach for calculating κ. BAs also has an advantageous RT coefficient of thermal expansion, which, combined with the high κ value, suggests that it is a promising material for use in thermal management applications.

  5. Dispersion relations in heavily-doped nanostructures

    CERN Document Server

    Ghatak, Kamakhya Prasad

    2016-01-01

    This book presents the dispersion relation in heavily doped nano-structures. The materials considered are III-V, II-VI, IV-VI, GaP, Ge, Platinum Antimonide, stressed, GaSb, Te, II-V, HgTe/CdTe superlattices and Bismuth Telluride semiconductors. The dispersion relation is discussed under magnetic quantization and on the basis of carrier energy spectra. The influences of magnetic field, magneto inversion, and magneto nipi structures on nano-structures is analyzed. The band structure of optoelectronic materials changes with photo-excitation in a fundamental way according to newly formulated electron dispersion laws. They control the quantum effect in optoelectronic devices in the presence of light. The measurement of band gaps in optoelectronic materials in the presence of external photo-excitation is displayed. The influences of magnetic quantization, crossed electric and quantizing fields, intense electric fields on the on the dispersion relation in heavily doped semiconductors and super-lattices are also disc...

  6. Absorption intensity tunability in the near infrared region using phase-change nanostructure (Presentation Recording)

    Science.gov (United States)

    Ozdemir, Abdurrahman; Saraydemir, Safak; Barut, Bilal; Kocer, Hasan

    2015-08-01

    Nanostructured thin film absorbers embedded with phase-change material (PCM) can provide large level of absorption intensity tunability in the near-infrared region. Germanium Antimonide Tellurite (Ge2Sb1Te4-GST) was employed as the phase-change material in the designed structures. The structure is composed of a periodic grating-type array of 200 nm thick Au buried with 100 nm-thick GST layer from the top of the Au layer. The period of the gratings is 2 μm and in each period, GST width is 0.5 μm. GST was selected as the active PCM because its optical properties undergo a substantial change during a structural transition from the amorphous to the crystalline phase. The optical absorption properties of the designed structures with respect to the geometric and material parameters were systematically investigated using finite-difference time-domain computations. It was shown that absorption intensity in the near-infrared region was tuned from the near-perfect to the near-zero level by switching the PCM from its amorphous to crystalline states. The distributions of the electric field and absorbed power at the resonant wavelengths with respect to different phases of the GST were investigated to further explain the physical origin of the absorption tuning. This study provides a path toward the realization of tunable infrared absorbers for the applications, such as selective infrared emitters, infrared camouflage, sensors, and photovoltaic devices.

  7. Real-time observation of coherent acoustic phonons generated by an acoustically mismatched optoacoustic transducer using x-ray diffraction

    International Nuclear Information System (INIS)

    The spectrum of laser-generated acoustic phonons in indium antimonide coated with a thin nickel film has been studied using time-resolved x-ray diffraction. Strain pulses that can be considered to be built up from coherent phonons were generated in the nickel film by absorption of short laser pulses. Acoustic reflections at the Ni–InSb interface leads to interference that strongly modifies the resulting phonon spectrum. The study was performed with high momentum transfer resolution together with high time resolution. This was achieved by using a third-generation synchrotron radiation source that provided a high-brightness beam and an ultrafast x-ray streak camera to obtain a temporal resolution of 10 ps. We also carried out simulations, using commercial finite element software packages and on-line dynamic diffraction tools. Using these tools, it is possible to calculate the time-resolved x-ray reflectivity from these complicated strain shapes. The acoustic pulses have a peak strain amplitude close to 1%, and we investigated the possibility to use this device as an x-ray switch. At a bright source optimized for hard x-ray generation, the low reflectivity may be an acceptable trade-off to obtain a pulse duration that is more than an order of magnitude shorter

  8. Superlattice Barrier Infrared Detector Development at the Jet Propulsion Laboratory

    Science.gov (United States)

    Ting, David Z.; Soibel, Alexander; Rafol, Sir B.; Nguyen, Jean; Hoglund, Linda; Khoshakhlagh, Arezou; Keo, Sam A.; Liu, John K.; Mumolo, Jason M.

    2011-01-01

    We report recent efforts in achieving state-of-the-art performance in type-II superlattice based infrared photodetectors using the barrier infrared detector architecture. We used photoluminescence measurements for evaluating detector material and studied the influence of the material quality on the intensity of the photoluminescence. We performed direct noise measurements of the superlattice detectors and demonstrated that while intrinsic 1/f noise is absent in superlattice heterodiode, side-wall leakage current can become a source of strong frequency-dependent noise. We developed an effective dry etching process for these complex antimonide-based superlattices that enabled us to fabricate single pixel devices as well as large format focal plane arrays. We describe the demonstration of a 1024x1024 pixel long-wavelength infrared focal plane array based the complementary barrier infrared detector (CBIRD) design. An 11.5 micron cutoff focal plane without anti-reflection coating has yielded noise equivalent differential temperature of 53 mK at operating temperature of 80 K, with 300 K background and cold-stop. Imaging results from a recent 10 ?m cutoff focal plane array are also presented.

  9. Infrared detectors: Advances, challenges and new technologies

    International Nuclear Information System (INIS)

    Human knowledge of infrared (IR) radiation is about 200 years old. However it was in the late 20th century that we developed a wide range of smart technologies for detection and started to take advantage for our benefit. Today IR detector technology is in its 3rd generation and comes with challenging demands. Based on the propagation of IR radiation through free space it is divided into different transmission windows. The most interesting for thermal imaging are the mid-wave IR (MWIR) and the long-wave IR (LW IR). Infrared detectors for thermal imaging have a number of applications in industry, security, search and rescue, surveillance, medicine, research, meteorology, climatology and astronomy. Currently high-performance IR imaging technology is mainly based on epitaxially grown structures of the small-bandgap bulk alloy mercury-cadmium-telluride (MCT), indium antimonide (InSb) and GaAs based quantum-well infrared photodetectors (QWIPs), depending on the application and wavelength range. However, they operate at low temperatures requiring costly and bulky cryogenic systems. In addition there is always a need for better performance, which generates possibilities for developing new technologies. Some emerging technologies are quantum dot infrared photodetectors (QDIPs), type-II strained layer super-lattice, and QDIPs with type-II band alignment. In this report a brief review of the current and new technologies for high performance IR detectors, will be presented

  10. Anodic fluoride passivation of type II InAs/GaSb superlattice for short-wavelength infrared detector

    International Nuclear Information System (INIS)

    One of the major challenges of antimonide-based devices arises owing to the large number of surface states generated during fabrication processes. Surface passivation and subsequent capping of the surfaces are absolutely essential for any practical applicability of this material system. In this paper, we proposed a new passivation method (zinc sulfide coating after anodic fluoride) for InAs/GaSb superlattice infrared detectors. InAs/GaSb superlattice short-wavelength infrared materials were grown by molecular beam epitaxy on GaSb (100) substrates. A GaSb buffer layer, which can decrease the occurrence of defects with similar pyramidal structure, was grown for optimized superlattice growth condition. High resolution X-ray diffraction indicated that the period of the superlattice corresponding to fourth satellite peak was 39.77 Aa. The atomic force microscopy images show the roughness was below 1.7 nm. The result of photoresponse spectra shows that the cutoff wavelength was 3.05 μm at 300 K. (orig.)

  11. Status of international co-operation. Case study: Elucidation of the cause and control of second impurity pattern in semiconductors

    Science.gov (United States)

    Nishinaga, Tatau

    1992-01-01

    Cause and control of the 2nd impurity patterns in tellurium doped gallium antimonide and sulfur doped indium phosphide semiconductors were studied. The semiconductors were made using the Travelling Heater Method (THM) on Spacelab SL-1 (1983) and D-1 (1985). Samples were chemically etched and observed by spatial resolution photo luminescence method. As a result, the condition to control the formation of the 2nd impurity pattern is elucidated, and crystal growth without 1st or 2nd impurity patterns can be obtained using the THM method in microgravity. Methods to remove the macrosteps formed by LPE (Liquid Phase Epitaxy), which is a method for the formation of semiconductor thin solids, are found. It is made clear that the latter result is attributable to ground technology improvement yielded by analyzing experiments in microgravity. It is made clear that accurate research on the formation and disappearance of 2nd impurity patterns and accurate measurement of physical constants, such as the diffusion coefficient, are possible in microgravity conditions due to lack of thermal convection.

  12. 34% Efficient InGaP/GaAs/GaSb Cell-Interconnected-Circuits for Line-Focus Concentrator Arrays

    Science.gov (United States)

    Fraas, L. M.; Daniels, W. E.; Huang, H. X.; Minkin, L. E.; Avery, J. E.; Chu, C.; Iles, P.; ONeill, M. J.; McDanal, A. J.; Piszczor, Mike

    2002-01-01

    While monolithic multi-junction cells are preferred for flat plate arrays, mechanically stacked multi-junction cells are superior for solar concentrator applications. Reasons for this are that the mechanical stacked configuration with high efficiency Gallium Antimonide cells allows utilization of a much wider range of the solar energy spectrum, and the ability to use voltage matched interconnects results in full use of low bandgap cell currents. Herein, data are presented for simple two terminal voltage-matched circuits using InGaP/GaAs/GaSb stacked cells showing 34% average circuit efficiency for a lot of 12 circuits given prismatic covers. These circuits have been designed to fit into the ultralight Stretched Lens Array being developed by NASA. With these new cell-interconnected-circuits, we project that the power density at GEO operating temperature can be increased from 296 W/m2 to 350 W/m2 while maintaining the specific power at 190 W/kg at the full wing level.

  13. Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

    International Nuclear Information System (INIS)

    The new metastable compound Cr1+xSb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni2In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr1+xSb crystallized. A change in the activation energy was observed for the diffusion process when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr1+xSb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr1.6Sb in Ni2In-type structure. • The new Cr-rich phase shows half-metallic behavior

  14. OPS laser EPI design for different wavelengths

    Science.gov (United States)

    Moloney, J. V.; Hader, J.; Li, H.; Kaneda, Y.; Wang, T. S.; Yarborough, M.; Koch, S. W.; Stolz, W.; Kunert, B.; Bueckers, C.; Chaterjee, S.; Hardesty, G.

    2009-02-01

    Design of optimized semiconductor optically-pumped semiconductor lasers (OPSLs) depends on many ingredients starting from the quantum wells, barrier and cladding layers all the way through to the resonant-periodic gain (RPG) and high reflectivity Bragg mirror (DBR) making up the OPSL active mirror. Accurate growth of the individual layers making up the RPG region is critical if performance degradation due to cavity misalignment is to be avoided. Optimization of the RPG+DBR structure requires knowledge of the heat generation and heating sinking of the active mirror. Nonlinear Control Strategies SimuLaseTM software, based on rigorous many-body calculations of the semiconductor optical response, allows for quantum well and barrier optimization by correlating low intensity photoluminescence spectra computed for the design, with direct experimentally measured wafer-level edge and surface PL spectra. Consequently, an OPSL device optimization procedure ideally requires a direct iterative interaction between designer and grower. In this article, we discuss the application of the many-body microscopic approach to OPSL devices lasing at 850nm, 1040nm and 2μm. The latter device involves and application of the many-body approach to mid-IR OPSLs based on antimonide materials. Finally we will present results on based on structural modifications of the epitaxial structure and/or novel material combinations that offer the potential to extend OPSL technology to new wavelength ranges.

  15. Semiconductor-topological insulator transition of two-dimensional SbAs induced by biaxial tensile strain

    Science.gov (United States)

    Zhang, Shengli; Xie, Meiqiu; Cai, Bo; Zhang, Haijun; Ma, Yandong; Chen, Zhongfang; Zhu, Zhen; Hu, Ziyu; Zeng, Haibo

    2016-06-01

    A stibarsen [derived from Latin stibium (antimony) and arsenic] or allemontite, is a natural form of arsenic antimonide (SbAs) with the same layered structure as arsenic and antimony. Thus, exploring the two-dimensional SbAs nanosheets is of great importance to gain insights into the properties of group V-V compounds at the atomic scale. Here, we propose a class of two-dimensional V-V honeycomb binary compounds, SbAs monolayers, which can be tuned from semiconductor to topological insulator. By ab initio density functional theory, both α-SbAs and γ-SbAs display a significant direct band gap, while others are indirect semiconductors. Interestingly, in an atomically thin β-SbAs polymorph, spin-orbital coupling is significant, which reduces its band gap by 200 meV. Especially under biaxial tensile strain, the gap of β-SbAs can be closed and reopened with concomitant change of band shapes, which is reminiscent of band inversion known in many topological insulators. In addition, we find that the Z2 topological invariant is 1 for β-SbAs under the tensile strain of 12%, and the nontrivial topological feature of β-SbAs is also confirmed by the gapless edge states which cross linearly at the Γ point. These ultrathin group-V-V semiconductors with outstanding properties are highly favorable for applications in alternative optoelectronic and quantum spin Hall devices.

  16. Structurally complex Zintl compounds for high temperature thermoelectric power generation

    Science.gov (United States)

    Zevalkink, Alexandra; Pomrehn, Gregory; Gibbs, Zachary; Snyder, Jeffrey

    2014-03-01

    Zintl phases, characterized by covalently-bonded substructures surrounded by highly electropositive cations, exhibit many of the characteristics desired for thermoelectric applications. Recently, we demonstrated promising thermoelectric performance (zT values between 0.4 and 0.9) in a class of Zintl antimonides that share a common structural motif: anionic moieties resembling infinite chains of linked tetrahedra. These compounds (A5M2 Sb6 and A3 M Sb3 compounds where A = Ca or Sr and M = Al, Ga and In) crystallize as four distinct, but closely related chain-forming structure types. Their large unit cells lead to exceptionally low lattice thermal conductivity due to the containment of heat in low velocity optical phonon modes. Here, we show that chemical substitutions on the A and M sites can be used to control the electronic and thermal transport properties and optimize the thermoelectric figure of merit. Doping with alio-valent elements allows for rational control of the carrier concentration, while isoelectronic substitutions can be used to fine-tune the intrinsic properties. A combination of Density Functional calculations and classical transport models was used to explain the experimentally observed transport properties of these compounds.

  17. Improved retrieval of gas abundances from near-infrared solar FTIR spectra measured at the Karlsruhe TCCON station

    Science.gov (United States)

    Kiel, M.; Wunch, D.; Wennberg, P. O.; Toon, G. C.; Hase, F.; Blumenstock, T.

    2016-02-01

    We present a modified retrieval strategy for solar absorption spectra recorded by the Karlsruhe Fourier Transform Infrared (FTIR) spectrometer, which is operational within the Total Carbon Column Observing Network (TCCON). In typical TCCON stations, the 3800-11 000 cm-1 spectral region is measured on a single extended Indium Gallium Arsenide (InGaAs) detector. The Karlsruhe setup instead splits the spectrum across an Indium Antimonide (InSb) and InGaAs detector through the use of a dichroic beam splitter. This permits measurements further into the mid-infrared (MIR) that are of scientific interest, but are not considered TCCON measurements. This optical setup induces, however, larger variations in the continuum level of the solar spectra than the typical TCCON setup. Here we investigate the appropriate treatment of continuum-level variations in the retrieval strategy using the spectra recorded in Karlsruhe. The broad spectral windows used by TCCON require special attention with respect to residual curvature in the spectral fits. To accommodate the unique setup of Karlsruhe, higher-order discrete Legendre polynomial basis functions have been enabled in the TCCON retrieval code to fit the continuum. This improves spectral fits and air-mass dependencies for affected spectral windows. After fitting the continuum curvature, the Karlsruhe greenhouse gas records are in good agreement with other European TCCON data sets.

  18. Determination of thermal emission spectra maximizing thermophotovoltaic performance using a genetic algorithm

    CERN Document Server

    DeSutter, John; Francoeur, Mathieu

    2016-01-01

    Optimal radiator thermal emission spectra maximizing thermophotovoltaic (TPV) conversion efficiency and output power density are determined when temperature effects in the cell are considered. To do this, a framework is designed in which a TPV model that accounts for radiative, electrical and thermal losses is coupled with a genetic algorithm. The TPV device under study involves a spectrally selective radiator at a temperature of 2000 K, a gallium antimonide cell, and a cell thermal management system characterized by a fluid temperature and a heat transfer coefficient of 293 K and 600 Wm-2K-1. It is shown that a maximum conversion efficiency of 38.8% is achievable with an emission spectrum that has emissivity of unity between 0.719 eV and 0.763 eV and zero elsewhere. This optimal spectrum is less than half of the width of those when thermal losses are neglected. A maximum output power density of 41708 Wm-2 is achievable with a spectrum having emissivity values of unity between 0.684 eV and 1.082 eV and zero e...

  19. Photoconduction spectroscopy of p-type GaSb films

    Energy Technology Data Exchange (ETDEWEB)

    Shura, M.W., E-mail: Megersa.Shura@live.nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Wagener, V.; Botha, J.R.; Wagener, M.C. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 {mu}m. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley-Read-Hall lifetime and maximum value of the surface recombination velocity.

  20. Strongly correlated electron phenomena in Pr-based filled skutterudite compounds

    International Nuclear Information System (INIS)

    Recent experiments on the Pr-based filled skutterudite arsenides and antimonides PrOs4Sb12, Pr(Os1-xRux)4Sb12, Pr1-xNdxOs4Sb12, PrFe4As12, PrRu4As12, and PrOs4As12 are reviewed. The heavy fermion compound PrOs4Sb12 exhibits unconventional strong-coupling superconductivity below Tc=1.85K that breaks time reversal symmetry, apparently consists of several distinct superconducting phases, and may involve triplet spin pairing of electrons. Studies of the alloy systems Pr(Os1-xRux)4Sb12 and Pr1-xNdxOs4Sb12 revealed rich T-x phase diagrams and a strong suppression of the high field ordered phase and the unconventional superconductivity of PrOs4Sb12 with Ru substitution. Among the three Pr-based filled skutterudite arsenides, PrFe4As12 has a ferromagnetic ground state, PrRu4As12 exhibits conventional BCS superconductivity, and PrOs4As12 is an antiferromagnet

  1. Strongly correlated electron phenomena in Pr-based filled skutterudite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Maple, M.B. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States)]. E-mail: mbmaple@physics.ucsd.edu; Henkie, Z. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland); Yuhasz, W.M. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States); Ho, P.-C. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States); Yanagisawa, T. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States); Sayles, T.A. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States); Butch, N.P. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States); Jeffries, J.R. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA (United States); Pietraszko, A. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland)

    2007-03-15

    Recent experiments on the Pr-based filled skutterudite arsenides and antimonides PrOs{sub 4}Sb{sub 12}, Pr(Os{sub 1-x}Ru{sub x}){sub 4}Sb{sub 12}, Pr{sub 1-x}Nd{sub x}Os{sub 4}Sb{sub 12}, PrFe{sub 4}As{sub 12}, PrRu{sub 4}As{sub 12}, and PrOs{sub 4}As{sub 12} are reviewed. The heavy fermion compound PrOs{sub 4}Sb{sub 12} exhibits unconventional strong-coupling superconductivity below T{sub c}=1.85K that breaks time reversal symmetry, apparently consists of several distinct superconducting phases, and may involve triplet spin pairing of electrons. Studies of the alloy systems Pr(Os{sub 1-x}Ru{sub x}){sub 4}Sb{sub 12} and Pr{sub 1-x}Nd{sub x}Os{sub 4}Sb{sub 12} revealed rich T-x phase diagrams and a strong suppression of the high field ordered phase and the unconventional superconductivity of PrOs{sub 4}Sb{sub 12} with Ru substitution. Among the three Pr-based filled skutterudite arsenides, PrFe{sub 4}As{sub 12} has a ferromagnetic ground state, PrRu{sub 4}As{sub 12} exhibits conventional BCS superconductivity, and PrOs{sub 4}As{sub 12} is an antiferromagnet.

  2. Photoconduction spectroscopy of p-type GaSb films

    International Nuclear Information System (INIS)

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 μm. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley–Read–Hall lifetime and maximum value of the surface recombination velocity.

  3. Superconductivity of ternary metal compounds prepared at high pressures

    CERN Document Server

    Shirotani, I

    2003-01-01

    Various ternary metal phosphides, arsenides, antimonides, silicides and germanides have been prepared at high temperatures and high pressures. These ternary metal compounds can be classified into four groups: [1] metal-rich compounds MM' sub 4 X sub 2 and [2] MM'X, [3] non-metal-rich compounds MXX' and [4] MM' sub 4 X sub 1 sub 2 (M and M' = metal element; X and X' = non-metal element). We have studied the electrical and magnetic properties of these materials at low temperatures, and found many new superconductors with the superconducting transition temperature (T sub c) of above 10 K. The metal-rich compound ZrRu sub 4 P sub 2 with a tetragonal structure showed the superconducting transition at around 11 K, and had an upper critical field (H sub c sub 2) of 12.2 tesla (T) at 0 K. Ternary equiatomic compounds ZrRuP and ZrRuSi crystallize in two modifications, a hexagonal Fe sub 2 P-type structure [h-ZrRuP(Si)] and an orthorhombic Co sub 2 P-type structure [o-ZrRuP(Si)]. Both h-ZrRuP and h-ZrRuSi have rather h...

  4. Concentration and structure inhomogeneities in GaSb(Si) single crystals grown at different heat and mass transfer conditions

    Science.gov (United States)

    Serebryakov, Yu. A.; Prokhorov, I. A.; Vlasov, V. N.; Korobeynikova, E. N.; Zakharov, B. G.; Shul'pina, I. L.; Marchenko, M. P.; Fryazinov, I. V.

    2007-06-01

    Results of ground-based experiments on crystallization of gallium antimonide on the POLIZON facility carried out within the framework of space experiment preparation aboard FOTON satellite are submitted. Technical and technological opportunities of suppression of disturbing factors for improvement of quality of grown crystals in space are substantiated. Features of formation of concentration and structure inhomogeneities in GaSb:Si crystals grown under non-stationary and stationary convection conditions are investigated. Experimental data about structure and dopant distribution inhomogeneities are discussed taking into account results of numerical researches of GaSb:Si crystallization. Also earlier received results of modeling of GaSb:Te crystallization under close temperature conditions are used. Correlation between computational and experimental data is shown. The data on intensity of flows close to crystallization front are received at which non-stationary or stationary conditions of crystallization are realized. The forecast for space conditions is made. The influence of a rotating magnetic field on convection in melt for application in space experiment projected is investigated.

  5. Thin-film 'Thermal Well' Emitters and Absorbers for High-Efficiency Thermophotovoltaics

    CERN Document Server

    Tong, Jonathan K; Huang, Yi; Boriskina, Svetlana V; Chen, Gang

    2015-01-01

    A new approach is introduced to significantly improve the performance of thermophotovoltaic (TPV) systems by using low-dimensional thermal emitters and photovoltaic (PV) cells. By reducing the thickness of both the emitter and the PV cell, strong spectral selectivity in both thermal emission and absorption can be achieved by confining photons in trapped waveguide modes inside the thin-films that act as thermal analogs to quantum wells. Simultaneously, photo-excited carriers travel shorter distances across the thin-films reducing bulk recombination losses resulting in a lower saturation current in the PV cell. We predict a TPV efficiency enhancement with near-field coupling between the thermal emitter and the PV cell of up to 38.7% using a germanium (Ge) emitter at 1000 K and a gallium antimonide (GaSb) cell with optimized thicknesses separated by 100 nm. Even in the far-field limit, the efficiency is predicted to reach 31.5%, which is an order of magnitude higher than the Shockley Queisser limit of 1.6% for a...

  6. Crystal structure of LuCu4-xSb2 (x = 1.053)

    International Nuclear Information System (INIS)

    Crystal structure of new ternary antimonide LuCu4-xSb2 (x = 1.053(8)) was refined by means of powder diffraction method (diffractometer DRON-3M, Cu Kα-radiation, RB = 4.09, χ2 = 1.92). It crystallizes in orthorhombic type of structure ErFe4Ge2 (low-temperature modification): space group Pnnm, Pearson code oP14-2.11, a = 7.01189(14), b = 7.75061(15), c = 4.24323(8) A; Z = 2. Analysing the coordination environments of atoms it was shown, that investigated structure is an inclusion derivative of TiO2 structure type. TiO2, NiAs, MnBi, Ag2HgS2, Ni2In and RCu4-xSb2 (R Tm, Lu) structures belongs to the family of structures built up from the columns of filled octahedra and differ by the filling of space between them by different atoms or groups of atoms

  7. Superconductivity in ZrCuSiAs related structures with extended edge-shared FeAs4/4 tetrahedra

    International Nuclear Information System (INIS)

    The past three years have seen a significant research activity on the new class of Fe based superconductors (LnOFeAs, AFe2As2, AFeAs and FeSe) with maximum Tc of 55 K in Sm(O/F)FeAs. All these Fe-based superconductors consist of edge sharing distorted FeX4/4 (X = P, As and Se) tetrahedra which form the charge carrier layers. Superconductivity can be induced in these AFM semi-metals by doping of electrons or holes which modifies the electronic and magnetic structure of these materials. The Tc is very susceptible to distortion which affects the overlap of the Fe(3d) -As(4p) orbitals and hence fine tuning the structural parameters (Fe-As bond length, As-Fe-As bond angles) through chemical substitution is a major handle to control/design superconductors with high transition temperatures and high critical field. We discuss our results in this direction in which we have been successful in obtaining the first Sb -doped, P-doped oxypnictide superconductors and have also shown pressure to be helpful in enhancing the Tc. We also discuss some interesting non-superconducting antimonides of the type LnOMnSb showing metallic behavior (Ln = La and Pr) and metal-insulator transition (Ln=Ce). (author)

  8. Intermediate-valent Yb{sub 4}Rh{sub 7}Sb{sub 6} with cubic U{sub 4}Re{sub 7}Si{sub 6} type structure

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, Inga; Eul, Matthias; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2010-07-01

    Yb{sub 4}Rh{sub 7}Sb{sub 6} was syntesized by arc-melting of the elements. The structure was refined on the basis of single crystal X-ray diffractometer data: U{sub 4}Re{sub 7}Si{sub 6} type, Im3m, a = 865.9(2) pm, wR2 = 0.0557, 159 F{sup 2} values and 10 variables. The two crystallographically independent rhodium atoms have octahedral and tetrahedral antimony coordination with Rh-Sb distances ranging from 269 to 274 pm. These polyhedra are condensed via common edges and corners, leading to a complex three-dimensional [Rh{sub 7}Sb{sub 6}] network. Corrdination number 12 cavities within this network are filled by the ytterbium atoms. Temperature dependent magnetic susceptibility measurements show modified Curie-Weiss behavior and an experimental magnetic moment of 3.16(1){mu}{sub B}Yb atom, pointing to intermediate-valent ytterbium. Magnetization measurements at 5 K give hint for short-range magnetic ordering. {sup 121}Sb Moessbauer spectra confirm the single crystallographic antimony site and antimonide character. (orig.)

  9. Fowler-Nordheim field emission effects in semiconductor nanostructures

    CERN Document Server

    Bhattacharya, Sitangshu

    2012-01-01

    This monograph solely presents the Fowler-Nordheim field emission (FNFE) from semiconductors and their nanostructures. The materials considered are quantum confined non-linear optical, III-V, II-VI, Ge, Te, carbon nanotubes, PtSb2, stressed materials, Bismuth, GaP, Gallium Antimonide, II-V, Bi2Te3, III-V, II-VI, IV-VI and HgTe/CdTe superlattices with graded interfaces and effective mass superlattices under magnetic quantization and quantum wires of the aforementioned superlattices. The FNFE in opto-electronic materials and their quantum confined counterparts is studied in the presence of light waves and intense electric fields on the basis of newly formulated electron dispersion laws that control the studies of such quantum effect devices. The importance of band gap measurements in opto-electronic materials in the presence of external fields is discussed from this perspective. This monograph contains 200 open research problems which form the very core and are useful for Ph. D students and researchers. The boo...

  10. Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

    Energy Technology Data Exchange (ETDEWEB)

    Regus, Matthias [Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel, Max-Eyth-Str. 2, 24118 Kiel (Germany); Mankovsky, Sergiy; Polesya, Svitlana; Kuhn, Gerhard [Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, D-81377 München (Germany); Ditto, Jeffrey [Department of Chemistry and Materials Science Institute, University of Oregon, 373 Klamath Hall, Eugene, OR 97403 (United States); Schürmann, Ulrich [Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstr. 2, 24118 Kiel (Germany); Jacquot, Alexandre; Bartholomé, Kilian [Fraunhofer Institute for Physical Measurement Techniques IPM, Thermoelectric Systems, Heidenhofstraße 8, 79110 Freiburg (Germany); Näther, Christian [Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel, Max-Eyth-Str. 2, 24118 Kiel (Germany); Winkler, Markus; König, Jan D.; Böttner, Harald [Fraunhofer Institute for Physical Measurement Techniques IPM, Thermoelectric Systems, Heidenhofstraße 8, 79110 Freiburg (Germany); Kienle, Lorenz [Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstr. 2, 24118 Kiel (Germany); Johnson, David C. [Department of Chemistry and Materials Science Institute, University of Oregon, 373 Klamath Hall, Eugene, OR 97403 (United States); Ebert, Hubert [Department of Chemistry, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, D-81377 München (Germany); Bensch, Wolfgang, E-mail: wbensch@ac.uni-kiel.de [Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel, Max-Eyth-Str. 2, 24118 Kiel (Germany)

    2015-10-15

    The new metastable compound Cr{sub 1+x}Sb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni{sub 2}In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr{sub 1+x}Sb crystallized. A change in the activation energy was observed for the diffusion process when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr{sub 1+x}Sb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr{sub 1.6}Sb in Ni{sub 2}In-type structure. • The new Cr-rich phase shows half-metallic behavior.

  11. Synthesis, crystallographic and magnetic properties of protactinium pnictides

    International Nuclear Information System (INIS)

    From a theoretical point of view, protactinium lies in a very important place in the periodic system for it seems to be the first element of the actinide series where the 5f state is occupied. We have studied protactinium pnictides, particularly arsenides and antimonides. PaAs2, Pa3As4, PaSb2 and Pa3Sb4 were synthetized and their crystallographic properties were determined and discussed. We have measured the magnetic susceptibilities of PaC, PaAs2 and PaSb2. Protactinium exhibits a dual character. In its monocarbide, which is a weakly diamagnet, it behaves as a transition element while in the temperature independent paramagnets PaAs2 and PaSb2, it behaves like a 'f' element. This 'f' element character increases with increasing metal-metal distances. Furthermore the radial expansion of the protactinium 5f orbital seems to be more important than the Uranium one, and consequently the corresponding protactinium 5f electrons are less localized. In addition, some protactinium chalcogenides (βPaS2, γPaSe2 and PaOSe) have been identified

  12. Performance of a Double Gate Nanoscale MOSFET (DG-MOSFET Based on Novel Channel Materials

    Directory of Open Access Journals (Sweden)

    Rakesh Prasher

    2013-03-01

    Full Text Available In this paper, we have studied a double gate nanoscale MOSFET for various channel materials using simulation approach. The device metrics considered at the nanometer scale are subthreshold swing (SS, drain induced barrier lowering (DIBL, on and off current, carrier injection velocity (vinj, etc. The channel materials studied are Silicon (Si, Germanium (Ge, Gallium Arsenide (GaAs, Zinc Oxide (ZnO, Zinc Sulfide (ZnS, Indium Arsenide (InAs, Indium Phosphide (InP and Indium Antimonide (InSb. The results suggest that InSb and InAs materials have highest Ion and lowest Ioff values when used in the channel of the proposed MOSFET. Besides, InSb has the highest values for Ion / Ioff ratio, vinj, transconductance (gm and improved short channel effects (SS = 59.71 and DIBL = 1.14, both are very close to ideal values. More results such as effect of quantum capacitance verses gate voltage (Vgs, drain current (Ids vs. gate voltage and drain voltage (Vds, ratio of transconductance (gm and drain current (Id vs. gate voltage, average velocity vs. gate voltage and injection velocity (Vinj for the mentioned channel materials have been investigated. Various results obtained indicate that InSb and InAs as channel material appear to be suitable for high performance logic and even low operating power requirements for future nanoscale devices as suggested by latest ITRS reports.

  13. MTI Focal Plane Assembly Design and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Ballard, M.; Rienstra, J.L.

    1999-06-17

    The focal plane assembly for the Multispectral Thermal Imager (MTI) consists of sensor chip assemblies, optical filters, and a vacuum enclosure. Sensor chip assemblies, composed of linear detector arrays and readout integrated circuits, provide spatial resolution in the cross-track direction for the pushbroom imager. Optical filters define 15 spectral bands in a range from 0.45 {micro}m to 10.7 {micro}m. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. Three pairs of sensor chip assemblies (SCAs) are required to provide cross-track coverage in all 15 spectral bands. Each pair of SCAs includes detector arrays made from silicon, iridium antimonide, and mercury cadmium telluride. Read out integrated circuits multiplex the signals from the detectors to 18 separate video channels. Optical filter assemblies defining the spectral bands are mounted over the linear detector arrays. Each filter assembly consists of several filter strips bonded together side-by-side. The MTI focal plane assembly has been integrated with the rest of the payload and has undergone detailed testing and calibration. This paper includes representative test data for the various spectral bands and the overall performance of the focal plane assembly.

  14. Fast, High-Precision Readout Circuit for Detector Arrays

    Science.gov (United States)

    Rider, David M.; Hancock, Bruce R.; Key, Richard W.; Cunningham, Thomas J.; Wrigley, Chris J.; Seshadri, Suresh; Sander, Stanley P.; Blavier, Jean-Francois L.

    2013-01-01

    The GEO-CAPE mission described in NASA's Earth Science and Applications Decadal Survey requires high spatial, temporal, and spectral resolution measurements to monitor and characterize the rapidly changing chemistry of the troposphere over North and South Americas. High-frame-rate focal plane arrays (FPAs) with many pixels are needed to enable such measurements. A high-throughput digital detector readout integrated circuit (ROIC) that meets the GEO-CAPE FPA needs has been developed, fabricated, and tested. The ROIC is based on an innovative charge integrating, fast, high-precision analog-to-digital circuit that is built into each pixel. The 128×128-pixel ROIC digitizes all 16,384 pixels simultaneously at frame rates up to 16 kHz to provide a completely digital output on a single integrated circuit at an unprecedented rate of 262 million pixels per second. The approach eliminates the need for off focal plane electronics, greatly reducing volume, mass, and power compared to conventional FPA implementations. A focal plane based on this ROIC will require less than 2 W of power on a 1×1-cm integrated circuit. The ROIC is fabricated of silicon using CMOS technology. It is designed to be indium bump bonded to a variety of detector materials including silicon PIN diodes, indium antimonide (InSb), indium gallium arsenide (In- GaAs), and mercury cadmium telluride (HgCdTe) detector arrays to provide coverage over a broad spectral range in the infrared, visible, and ultraviolet spectral ranges.

  15. Segregation of antimony in InP in MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Weeke, Stefan

    2008-07-01

    In this work the segregation of antimony in indium phosphide in metal organic vapour phase epitaxy (MOVPE)was systematically investigated. Therefore phosphine stabilized InP surfaces were treated with tri-methyl-antimony (TMSb) in MOVPE. An antimony rich Sb/InP surface was established, showing a typical spectra for the antimonides observed in reflectance anisotropy spectroscopy (RAS).Adsorption and desorption of antimony are investigated, as well as the incorporation of Sb during overgrowth of the Sb/InP surface with InP. Therefore the growth parameters temperature, TMSb partial pressure and treatment time are varied and their influence investigated. The experiments are monitored in-situ with RAS, the achieved data is correlated with ex-situ characterisation such as X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). It is shown that under treatment with TMSb a stable Sb/InP surface is formed within seconds, which does not change under further TMSb treatment. This process is rarely influenced by the TMSb partial pressure. On the contrary, the desorption of Sb is a very slow process. Two main processes can be distinguished: The desorption of excess Sb from the surface and the formation of the MOVPE prepared InP (2 x 1) surface. The reaction velocity of adsorption and desorption increases with temperature. Above a critical value the increase of TMSb partial pressure has no influence on the time for desorption. During overgrowth of the Sb/InP surface the opposite temperature dependence is observed: with increasing growth temperature the typical spectra for antimonides is observed longer. An analysis of the grown samples with XRD and SIMS showed the formation of an InPSb double quantum well. One layer is formed at the interface, the second one 50 nm-120 nm deep in the InP. The location of the 2nd InPSb layer can be correlated with the vanishing of the Sb signature in RAS. The distance between the quantum wells increases with growth temperature, until it

  16. Structural chemistry and phase relations in the ternary systems: rare earth (Nd)-Fe-(As,Sb,Bi)

    International Nuclear Information System (INIS)

    Phase equilibria in the system Nd-Fe-Sb have been determined in an isothermal section at 800 deg C. No compatibility was observed between Nd and the binary iron antimonides. There is virtually no solid solubility of Sb in binary Nd2Fe17. Seven ternary compounds were found to exist: Nd6Fe13Sb, NdFe3Sb2, NdFe2-xSb2, NdFe1-xSb2, 'Nd2Fe 3-xSb5', 'NdFeSb3'. The crystal structure of the latter two phases have not yet been characterized. Single crystal refinement of the Nd6Fe13Sb compound revealed isotypism with the Nd6Fe13Si structure type. A series of homologous compounds RE6(Fe, Co)13(As, Sb, Bi, Cu, Zn, Cd, Hg) have been prepared with RE= La, Pr, Nd, Sm. NdFe3Sb2 is the tetragonal high temperature modification of the orthorhombic NdFe2-xSb2 with significant Fe deficiency. Four-circle diffractometer data enabled refinement of the crystal structure of NdFe3Sb2 with the space group I4/mmm and Imm2 for the NdFe2-xSb2 structure. In contrast to the Pr, Sm compounds the isotypic La and Ce containing compounds show no orthorhombic distortion of the tetragonal diffraction pattern. Single crystal structure refinement revealed isotypism of NdFe1-xSb2 with the ZrCuSi2 structure type. Compounds RE(Fe, Co)1-xSb2 with RE= La, Ce, Pr, Sm, Gd showed isotypism with NdFe1-xSb2

  17. Uncooled infrared monolithic imaging sensor using pyroelectric polymer

    Science.gov (United States)

    Coutures, Jean-Louis; Lemaitre, Regine; Pourquier, E.; Boucharlat, Gilles C.; Tribolet, Philippe

    1995-09-01

    P(VF2-TrFE) pyroelectric copolymer is chosen for its high level of compatibility with existing microelectronics processes, and convenient electrical properties for infrared (IR) 8 to 14 micrometer imagery in the performance range of NETD 0.1 K to 1 K. Low cost sensors, achievable thanks to the monolithic silicon wafer processing, standard package assembly, and uncooled operations, allow us to address a lot of low-end applications in which conventional IR imaging techniques -- high priced hybrid mercury cadmium telluride or indium antimonide arrays, liquid nitrogen cooling and sophisticated image processing -- are nowadays incompatible with large volume user's needs and market prices. The paper describes pyroelectric device trade-offs, architecture, and process. Based on the interline architecture, the sensor performances of the TH 7441A 128 by 128 area array infrared detector are presented: compatible with 1 inch optics, the square array is made of an 80 by 80 micrometer squared pixel, on a pixel pitch of 85 micrometer. The CCD multiplexer using patented on-site processing is designed to deliver the image information at the maximum rate of 50 image/s. Lower rates are achievable. Imaging performances are the following: a NETD of 1.7 K is achieved with an integration time of 10 ms and the use of a f/1 optics presenting a transmission of 0.8. Recent improvements in the properties of the pyroelectric sandwich include thermal insulation of the pyroelectric layer through mixed air-polyimide material and pixel side to side insulation. Thanks to on-wafer pixel reticulation, an increased modulation transfer function of 51% at Nyquist frequency is achieved.

  18. Improvement of the retrieval used for Karlsruhe TCCON data

    Science.gov (United States)

    Kiel, M.; Wunch, D.; Wennberg, P. O.; Toon, G. C.; Hase, F.; Blumenstock, T.

    2015-11-01

    We present a modified retrieval strategy for solar absorption spectra recorded by the Karlsruhe Fourier Transform Infrared (FTIR) spectrometer which is operational within the Total Carbon Column Observing Network (TCCON). In typical TCCON stations, the (3800-11 000) cm-1 spectral region is measured on a single extended Indium Gallium Arsenide (InGaAs) detector. The Karlsruhe setup instead splits the spectrum across an Indium Antimonide (InSb) and InGaAs detector through the use of a dichroic beam splitter. This permits measurements further into the mid infrared (MIR) that are of scientific interest, but are not considered TCCON measurements. This optical setup induces, however, larger variations in the continuum level of the solar spectra than the typical TCCON setup. Here we investigate the appropriate treatment of continuum level variations in the retrieval strategy using the spectra recorded in Karlsruhe. The broad spectral windows used by TCCON require special attention with respect to residual curvature in the spectral fits. To accommodate the unique setup of Karlsruhe, higher order discrete Legendre polynomial basis functions have been enabled in the TCCON retrieval code to fit the continuum. This improves spectral fits and airmass dependencies for affected spectral windows. After fitting the continuum curvature, the Karlsruhe greenhouse gas records are in good agreement with other European TCCON datasets. A new version (R1) of the Karlsruhe data using the modified retrieval strategy is available through CDIAC (http://tccon.ornl.gov). Future scientific studies should use this superior R1 data, instead of the obsolete R0 data.

  19. Characterization of InSb Nanoparticles Synthesized Using Inert Gas Condensation

    Science.gov (United States)

    Pandya, Sneha G.; Kordesch, Martin E.

    2015-06-01

    Nanoparticles (NPs) of indium antimonide (InSb) were synthesized using a vapor phase synthesis technique known as inert gas condensation (IGC). NPs were directly deposited, at room temperature and under high vacuum, on glass cover slides, TEM grids and (111) p-type silicon wafers. TEM studies showed a bimodal distribution in the size of the NPs with average particle size of 13.70 nm and 33.20 nm. The Raman spectra of InSb NPs exhibited a peak centered at 184.27 cm-1, which corresponds to the longitudinal optical (LO) modes of phonon vibration in InSb. A 1:1 In-to-Sb composition ratio was confirmed by energy dispersive X-ray (EDX). X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HRTEM) studies revealed polycrystalline behavior of these NPs with lattice spacing around 0.37 and 0.23 nm corresponding to the growth directions of (111) and (220), respectively. The average crystallite size of the NPs obtained using XRD peak broadening results and the Debye-Scherrer formula was 25.62 nm, and the value of strain in NPs was found to be 0.0015. NP's band gap obtained using spectroscopy and Fourier transform infrared (FTIR) spectroscopy was around 0.43-0.52 eV at 300 K, which is a blue shift of 0.26-0.35 eV. The effects of increased particle density resulting into aggregation of NPs are also discussed in this paper.

  20. A method of monitoring the temperature of the photoconductive antenna

    Science.gov (United States)

    Liu, Hong; Wang, Yiqi; Li, Zhou; Bai, Yang; Pu, Ting; Kuang, Tingting; Chen, Kejian

    2014-11-01

    Photoconductive antenna (PCA), as the most widely used emitter (or detector) in Terahertz time-domain spectroscopy (TDS) system, virtually acts as a semiconductor switch, whose electrical conductivity controlled by pump light. At the same time, the heat caused by the pump light and the electrical bias will be stacked in a tiny area. Inevitably, the thermal effects, which may reduce the performance of PCA and the operational lifetime of device, need to be considered, especially for that generated by a compact package fiber-pigtailed photoconductive antenna. Nonetheless, there still lacks of relevant reports about real-time temperature monitoring for PCA. This paper proposes a method to obtain the temperature information by observing the temperature dependent frequency drifting of radiation spectroscopy. In other words, it converts the temperature information via analyzing the radiation spectrum of the conventional TDS system. In this work, we simulate a design of meta-atom-loaded PCA with indium antimonide (InSb). As a kind of temperature-dependent permittivity of the semiconductor, InSb is stuffed into the gap of split-ring resonator (SRR). When the temperature increases from 300K to 380 K, the resonance frequency shifts from 0.582THz to 0.678THz (a shift more than 16%), calculated by the commercial software-CST. The significant blue shift is caused by the SRR loading temperature sensitive materials, well analyzed by the LC resonant circuit model. Then, one can clearly obtain the actual antenna temperature from the radiation spectrum through the relationship between temperature and resonance frequency. Always, this simply method could be applied to shift the peak frequency of spectrum for various applications.

  1. Modeling and deformation analyzing of InSb focal plane arrays detector under thermal shock

    Science.gov (United States)

    Zhang, Xiaoling; Meng, Qingduan; Zhang, Liwen; Lv, Yanqiu

    2014-03-01

    A higher fracture probability appearing in indium antimonide (InSb) infrared focal plane arrays (IRFPAs) subjected to the thermal shock test, restricts its final yield. In light of the proposed equivalent method, where a 32 × 32 array is employed to replace the real 128 × 128 array, a three-dimensional modeling of InSb IRFPAs is developed to explore its deformation rules. To research the damage degree to the mechanical properties of InSb chip from the back surface thinning process, the elastic modulus of InSb chip along the normal direction is lessened. Simulation results show when the out-of-plane elastic modulus of InSb chip is set with 30% of its Young's modulus, the simulated Z-components of strain distribution agrees well with the top surface deformation features in 128 × 128 InSb IRFPAs fracture photographs, especially with the crack origination sites, the crack distribution and the global square checkerboard buckling pattern. Thus the Z-components of strain are selected to explore the deformation rules in the layered structure of InSb IRFPAs. Analyzing results show the top surface deformation of InSb IRFPAs originates from the thermal mismatch between the silicon readout integrated circuits (ROIC) and the intermediate layer above, made up of the alternating indium bump array and the reticular underfill. After passing through both the intermediate layer and the InSb chip, the deformation amplitude is reduced firstly from 2.23 μm to 0.24 μm, finally to 0.09 μm. Finally, von Mises stress criterion is employed to explain the causes that cracks always appear in the InSb chip.

  2. Microminiature rotary Stirling cryocooler for compact, lightweight, and low-power thermal imaging systems

    Science.gov (United States)

    Filis, Avishai; Bar Haim, Zvi; Pundak, Nachman; Broyde, Ramon

    2009-05-01

    Novel compact and low power consuming cooled infrared thermal imagers as used in gyro-stabilized payloads of miniature unmanned aerial vehicles, Thermal small arms sights and tactical night vision goggles often rely on integral rotary micro-miniature closed cycle Stirling cryogenic engines. Development of EPI Antimonides technology and optimization of MCT technology allowed decreasing in order of magnitudes the level of dark current in infrared detectors thus enabling an increase in the optimal focal plane temperature in excess of 95K while keeping the same radiometric performances as achieved at 77K using regular technologies. Maintaining focal plane temperature in the range of 95K to 110K instead of 77K improves the efficiency of Stirling thermodynamic cycle thus enlarging cooling power and enabling the development of a mini micro cooler similar to RICOR's K562S model which is three times smaller, lighter and more compact than a standard tactical cryocooler like RICOR's K508 model. This cooler also features a new type of ball bearings and internal components which were optimized to fit tight bulk constraints and maintain the required life span, while keeping a low level of vibration and noise signature. Further, the functions of management the brushless DC motor and temperature stabilization are delivered by the newly developed high performance sensorless digital controller. By reducing Dewar Detector thermal losses and increasing the focal plane temperature, longer life time operation is expected as was proved with RICOR's K508 model. Resulting from this development, the RICOR K562S model cryogenic engine consumes 1.2 - 3.0 WDC while operating in the closed loop mode and maintaining the typical focal plane arrays at 200-100K. This makes it compatible with very compact battery packages allowing further reduction of the overall thermal imager weight thus making it comparable with the compatible uncooled infrared thermal imager relying on a microbolometer detector

  3. InSb纳米结构材料与器件进展与展望%Progress and prospect of the nano structure material and device

    Institute of Scientific and Technical Information of China (English)

    郝秋来

    2014-01-01

    锑化铟(indium antimonide,熔点~525℃)是一种窄禁带半导体。由于其高的电子迁移率、小的有效质量及在极性III-V族材料中有最大的g因子,因而在高速器件、磁阻器件等方面具有潜在的电子学应用价值,而且已被广泛用于磁敏器件、红外探测器等。由于具有较大的波尔半径(60 nm),使得InSb纳米结构成为具有吸引力的进行量子效应研究的半导体。因为这些特性,已有一些关于InSb纳米结构生长的报道。本文描述了近期InSb纳米结构生长的情况。透射电子显微镜等形貌像显示纳米结构为纳米晶体或纳米线,器件制备和性能测试显示其下一步的应用能力。%Indium antimonide(InSb)(melting point~525 ℃)is a narrow bandgap semiconductor,and it is well known for its highest bulk electron mobility,smallest effective mass,and largest g factor among binary III-V materials.It therefore has potential electronic applications in high-speed devices and magnetoresistors,and has been used previous-ly as magnetic sensors and infrared(IR)detectors.It also has a large Bohr exciton radius of 60 nm,consequently mak-ing InSb nanostructure an attractive semiconductor for quantum effect studies.For its interesting properties,some work has been reported on the growth of InSb nanostructure.The recent growth of InSb nanostructure is described in this re-view.Transmission electron microscopy showed the nanostructure to be nanocrystal or nanowires.Device fabrication and characteristics show the application capability of next step.

  4. Experimental analysis of a porous burner operating on kerosene–vegetable cooking oil blends for thermophotovoltaic power generation

    International Nuclear Information System (INIS)

    Highlights: • Blends of kerosene–VCO fuels are successfully demonstrated for TPV power system. • Axial temperature distributions inside the combustion chamber are discussed. • Efficiencies are greatly affected by the change in fuel–air equivalence ratio. • CO and NOx emissions are affected by a change in fuel–air equivalence ratio. - Abstract: An experimental work was conducted to evaluate the performance and combustion characteristics of a porous burner for the cogeneration of heat and TPV applications. The main component comprised a novel tubular combustor that is designed to operate on several mixtures of gravity-fed liquid fuels and is integrated into an array of gallium antimonide (GaSb) TPV cells. Four mixtures of kerosene–vegetable cooking oil (VCO) were prepared and evaluated, as follows: 100% kerosene (100 kerosene), 90%/10% kerosene–VCO (90/10 KVCO), 75%/25% kerosene–VCO (75/25 KVCO), and 50%/50% kerosene–VCO (50/50 KVCO). The fuel–air equivalence ratios were varied from the rich blow-off condition to the lean region, and the corresponding electrical output and combustion characteristics were assessed. The maximum electrical efficiency of 1.03% was achieved using 50/50 KVCO, but the maximum radiant efficiency of 31.5% was obtained by using 100 kerosene. Experimental results indicated that increased fuel–air equivalence ratio adversely affected thermal efficiency. However, this shortcoming offsets the achievement of radiant power and efficiency. The thermal efficiency peaked at around stoichiometric mixture for all tested fuel blends. The combustion characteristics of the burner were clarified by analyzing the axial temperature profiles and emissions of carbon monoxide (CO) and nitrogen oxides (NOx). The temperature at the surface of the porous alumina was significantly higher than the developed flame temperature and the temperature at the exit of the burner. The CO emission fluctuated between 220 and 380 ppm in the lean region

  5. Comparison of ground-based FTIR measurements and EMAC model simulations of trace-gases columns near St. Petersburg (Russia) in 2009-2013

    Science.gov (United States)

    Virolainen, Yana; Makarova, Maria; Ionov, Dmitry; Polyakov, Alexander; Kirner, Oliver; Timofeyev, Yury; Poberovsky, Anatoly; Imhasin, Hamud

    2014-05-01

    The comparison of simulated atmospheric gases abundances with various experimental data is the very important stage of the numerical models validation and improvement process. In this study, we compare and discuss the observational data obtained from ground-based direct solar absorption measurements of high spectral-resolution FTIR spectrometer Bruker 125 HR operated at the Peterhof station (59.82 N, 29.88 E) with the 3-dimensional model EMAC (ECHAM5/MESSy Atmospheric Chemistry) calculations. The FTIR spectrometer has a maximum optical path difference of 180 cm, yielding a spectral resolution of unapodized spectra up to 0.005 cm-1. Two detectors, MCT (Mercury-Cadmium-Telluride) and InSb (Indium-Antimonide), cover the spectral range of 650-5400 cm-1 that includes many distinct and overlapping absorption lines, and allow the retrieval of a large number of atmospheric constituents. We applied two inversion codes using within NDACC infrared community: SFIT2 and PROFFIT for the retrieval of atmospheric gases column amounts from FTIR recorded spectra. The EMAC model is a numerical chemistry and climate simulation system that includes sub-models describing troposphere and middle atmosphere processes and their interaction with oceans, land and human influences. The simulation includes a comprehensive atmospheric chemistry setup for the troposphere, the stratosphere and the lower mesosphere. We applied the EMAC (ECHAM5 version 5.3.01, MESSy version 1.10) in the T42L39MA-resolution, i.e. with a spherical truncation of T42 (corresponding to a quadratic Gaussian grid of approximately 2.8 by 2.8 degrees in latitude and longitude) with 39 vertical hybrid pressure levels up to 0.01 hPa. The model simulation allows the comparison of the tropospheric gases (H2O, CO, CH4, and N2O) as well as the stratospheric gases (HCl, HNO3, NO2, O3 and ClONO2) that have been being continuously retrieved at the Peterhof station since 2009. In the study, we analyze the daily and monthly means of

  6. On the crystal structure and physical properties of the UFeSb2 compound

    International Nuclear Information System (INIS)

    Highlights: • Polycrystalline UFeSb2 was prepared by conventional arc-melting route. • An accurate crystal structure characterization of UFeSb2 was made. • UFeSb2 has a ferromagnetic-type transition at 31(1) K. • The ferromagnetic-like properties of UFeSb2 are determined by the U-sublattice. • Specific heat shows that UFeSb2 is a medium correlated electron system. - Abstract: The UFeSb2 ternary uranium antimonide has been prepared by arc-melting, followed by annealing at 750 °C for 1 week, and was characterized by means of powder X-ray diffraction, electrical resistivity, magnetization, Mössbauer spectroscopy and specific heat measurements. UFeSb2 crystallizes in the tetragonal HfCuSi2-type structure (space group P4/nmm, a = 0.43249(3) nm, c = 0.90962(7) nm), with the U, Fe and Sb atoms at the positions of Hf (2c), Cu (2b) and Si (2a and 2c), respectively. The nearest neighbor atoms of U are at distances close to or higher than the metallic radii sum, pointing to the possibility of a non negligible U magnetic moment, which contrasts with the very short Fe–Sb1 distances that indicate a probable collapse of Fe magnetic moments. The UFeSb2 undergoes a ferromagnetic-type transition at 31(1) K with a small saturation magnetization, suggesting for this compound a non-negligible U hybridization, itinerant magnetism and/or a complex magnetic structure. Mössbauer spectroscopy confirms that the magnetism is ruled by the U sub-lattice, with neither long-range magnetic ordering nor standard spin-glass behavior of the iron sub-lattice. The Sommerfeld coefficient of the electronic specific heat is γ = 51(1) mJ/mol K2, which classifies this compound as a medium correlated system

  7. Time-resolved X-ray diffraction with accelerator- and laser-plasma-based X-ray sources

    International Nuclear Information System (INIS)

    Femtosecond X-ray pulses are a powerful tool to investigate atomic motions triggered by femtosecond pump pulses. This thesis is dedicated to the production of such pulses and their use in optical pump - X-ray probe measurement. This thesis describes the laser-plasma-based sources available at the University of Duisburg-Essen. Part of it consists of the description of the design, built-up and characterization of a new ''modular'' X-ray source dedicated to optimize the X-ray flux onto the sample under investigation. The acoustic wave generation in femtosecond optically excited semiconductor (gallium arsenide) and metal (gold) was performed using the sources of the University of Duisburg-Essen. The physical answer of the material was modeled by a simple strain model for the semiconductor, pressure model for the metal, in order to gain information on the interplay of the electronic and thermal pressures rising after excitation. Whereas no reliable information could be obtain in gallium arsenide (principally due to the use of a bulk), the model for gold achieved very good agreement, providing useful information. The relaxation time of the electron to lattice energy was found to be (5.0±0.3) ps, and the ratio of the Grueneisen parameters was found to be γe / γi = (0.5±0.1). This thesis also describes the Sub-Picosecond Pulse Source (SPPS) which existed at the (formally) Stanford Linear Accelerator Center, an accelerator-based X-ray source, and two measurements performed with it. The first one is the detailed investigation of the phonon softening of the A1g mode launch in bismuth upon fluence excitation. Detailed information concerning the new equilibrium position and phonon frequency were obtained over extended laser pump fluences. The second measurement concerned the study of the liquid phase dynamics in a newly formed liquid phase following ultrafast melting in indium antimonide. The formation of the liquid phase and its development for excitations close to the

  8. High-speed Imaging of Global Surface Temperature Distributions on Hypersonic Ballistic-Range Projectiles

    Science.gov (United States)

    Wilder, Michael C.; Reda, Daniel C.

    2004-01-01

    times as short as 2 ns. The infrared camera uses an Indium Antimonide (InSb) sensor in the 3 to 5 micron band and is capable of integration times as short as 500 ns. The projectiles are imaged nearly head-on using expendable mirrors offset slightly from the flight path. The proposed paper will discuss the application of high-speed digital imaging systems in the NASA-Ames hypersonic ballistic range, and the challenges encountered when applying these systems. Example images of the thermal radiation from the blunt nose of projectiles flying at nearly 14 times the speed of sound will be given.

  9. Residual Gas Effects on Detached Solidification in Microgravity

    Science.gov (United States)

    Wilcox, William R.; Regel, Liya L.; Ramakrishnan; Kota, Arun; Anand, Gaurav

    2004-01-01

    Our long term goal has been to make detached solidification reproducible, which requires a full understanding of the mechanisms underlying it. Our Moving Meniscus Model of steady-state detachment predicts that it depends strongly on the surface tension of the melt and the advancing contact angle with the ampoule wall. Thus, the objective of the current project was to determine the influence of residual gases on the surface tension and contact angle of molten semiconductors on typical ampoule materials. Our focus was on the influence of oxygen on indium antimonide on clean silica ("quartz"). The research was performed by three chemical engineering graduate students, the third of whom will complete his research in the summer of 2005. Originally, we had planned to use a sealed silica cell containing a zirconia electrochemical element to control the oxygen partial pressure. However, zirconia requires an operating temperature above the 530 C melting point of InSb and is difficult to form a gas-tight seal with silica. Thus, we decided instead to flow an oxygen-containing gas through the cell. A special apparatus was designed, built and perfected. A piece of InSb was placed on a horizontal silica plate in a quartz cell. High purity argon, helium or hydrogen-containing gas is passed continuously through the cell while the oxygen concentration in the effluent gas is measured. The shape of the resulting drop was used to determine contact angle and surface tension of Ga-doped and high purity InSb. Oxygen appeared to decrease the contact angle, and definitely did not increase it. The following section gives the background for the research. Section 2 summarizes the results obtained on Ga-doped InSb with relatively high oxygen concentrations. Section 3 describes recent improvements made to the apparatus and methods of analysis. Section 4 gives recent results for high-purity InSb at low oxygen concentrations. Final results will be obtained only this summer (2005). Each section

  10. Structure and properties of EuTSb (T = Cu, Pd, Ag, Pt, Au) and YbIrSb

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Trinath; Schellenberg, Inga; Eul, Matthias; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2011-07-01

    The equiatomic antimonides EuTSb (T = Cu, Pd, Ag, Pt, Au) and YbIrSb were synthesized from the elements in sealed tantalum tubes in an induction furnace. The samples were investigated by powder X-ray diffraction and the structures were refined on the basis of single crystal X-ray diffractometer data: ZrBeSi type, P6{sub 3}/mmc, a = 450.7(5), c = 853.2(7) pm, wR2 = 0.032, 273 F{sup 2} values, 8 variables for EuCuSb, a = 474.9(1), c = 829.4(3) pm, wR2 = 0.028, 166 F{sup 2} values, 8 variables for EuAgSb, a = 467.1(2), c = 848.8(3) pm, wR2 = 0.042, 162 F{sup 2} values, 8 variables for EuAuSb, and TiNiSi type, space group Pnma, a = 762.5(3), b = 469.1(1), c = 792.1(1) pm, wR2 = 0.046, 670 F{sup 2} values, 20 variables for EuPdSb, and a = 700.7(1), b = 444.68(8), c = 781.3(1) pm, wR2 = 0.075, 592 F{sup 2} values, 20 variables for YbIrSb. The structures are ordered superstructure variants of the aristotype AlB{sub 2}3 with planar T{sub 3}Sb{sub 3} hexagons in EuTSb (T = Cu, Ag, Au) and puckered T{sub 3}Sb{sub 3} hexagons in EuTSb (T = Pd, Pt) and YbIrSb. TiNiSi type EuPtSb was characterized via powder data: a = 759.8(3), b = 465.4(3), c = 791.4(3) pm. Temperature dependent magnetic susceptibility measurements indicate antiferromagnetic ordering for all compounds. The samples were additionally characterized by {sup 121}Sb and {sup 151}Eu Moessbauer spectra. (orig.)

  11. Characterization of an infrared detector for high frame rate thermography

    Science.gov (United States)

    Fruehmann, R. K.; Crump, D. A.; Dulieu-Barton, J. M.

    2013-10-01

    The use of a commercially available photodetector based infrared thermography system, operating in the 2-5 µm range, for high frame rate imaging of temperature evolutions in solid materials is investigated. Infrared photodetectors provide a very fast and precise means of obtaining temperature evolutions over a wide range of science and engineering applications. A typical indium antimonide detector will have a thermal resolution of around 4 mK for room temperature measurements, with a noise threshold around 15 to 20 mK. However the precision of the measurement is dependent on the integration time (akin to exposure time in conventional photography). For temperature evolutions that occur at a moderate rate the integration time can be relatively long, enabling a large signal to noise ratio. A matter of increasing importance in engineering is the behaviour of materials at high strain rates, such as those experienced in impact, shock and ballistic loading. The rapid strain evolution in the material is usually accompanied by a temperature change. The temperature change will affect the material constitutive properties and hence it is important to capture both the temperature and the strain evolutions to provide a proper constitutive law for the material behaviour. The present paper concentrates on the capture of the temperature evolutions, which occur at such rates that rule out the use of contact sensors such as thermocouples and electrical resistance thermometers, as their response times are too slow. Furthermore it is desirable to have an indication of the temperature distribution over a test specimen, hence the full-field approach of IRT is investigated. The paper explores the many hitherto unaddressed challenges of IRT when employed at high speed. Firstly the images must be captured at high speeds, which means reduced integration times and hence a reduction in the signal to noise ratio. Furthermore, to achieve the high image capture rates the detector array must be

  12. Time-resolved X-ray diffraction with accelerator- and laser-plasma-based X-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Nicoul, Matthieu

    2010-09-01

    Femtosecond X-ray pulses are a powerful tool to investigate atomic motions triggered by femtosecond pump pulses. This thesis is dedicated to the production of such pulses and their use in optical pump - X-ray probe measurement. This thesis describes the laser-plasma-based sources available at the University of Duisburg-Essen. Part of it consists of the description of the design, built-up and characterization of a new ''modular'' X-ray source dedicated to optimize the X-ray flux onto the sample under investigation. The acoustic wave generation in femtosecond optically excited semiconductor (gallium arsenide) and metal (gold) was performed using the sources of the University of Duisburg-Essen. The physical answer of the material was modeled by a simple strain model for the semiconductor, pressure model for the metal, in order to gain information on the interplay of the electronic and thermal pressures rising after excitation. Whereas no reliable information could be obtain in gallium arsenide (principally due to the use of a bulk), the model for gold achieved very good agreement, providing useful information. The relaxation time of the electron to lattice energy was found to be (5.0{+-}0.3) ps, and the ratio of the Grueneisen parameters was found to be {gamma}{sub e} / {gamma}{sub i} = (0.5{+-}0.1). This thesis also describes the Sub-Picosecond Pulse Source (SPPS) which existed at the (formally) Stanford Linear Accelerator Center, an accelerator-based X-ray source, and two measurements performed with it. The first one is the detailed investigation of the phonon softening of the A{sub 1g} mode launch in bismuth upon fluence excitation. Detailed information concerning the new equilibrium position and phonon frequency were obtained over extended laser pump fluences. The second measurement concerned the study of the liquid phase dynamics in a newly formed liquid phase following ultrafast melting in indium antimonide. The formation of the liquid phase

  13. Interaction of coal-derived synthesis gas impurities with solid oxide fuel cell metallic components

    Science.gov (United States)

    Marina, Olga A.; Pederson, Larry R.; Coyle, Christopher A.; Edwards, Danny J.; Chou, Yeong-Shyung; Cramer, Carolyn N.

    Oxidation-resistant alloys find use as interconnect materials, heat exchangers, and gas supply tubing in solid oxide fuel cell (SOFC) systems, especially when operated at temperatures below ∼800 °C. If fueled with synthesis gas derived from coal or biomass, such metallic components could be exposed to impurities contained in those fuel sources. In this study, coupons of ferritic stainless steels Crofer 22 APU and SS 441, austenitic nickel-chromium superalloy Inconel 600, and an alumina-forming high nickel alloy alumel were exposed to synthesis gas containing ≤2 ppm phosphorus, arsenic and antimony, and reaction products were tested. Crofer 22 APU coupons coated with a (Mn,Co) 3O 4 protective layer were also evaluated. Phosphorus was found to be the most reactive. On Crofer 22 APU, the (Mn,Cr) 3O 4 passivation layer reacted to form an Mn-P-O product, predicted to be manganese phosphate from thermochemical calculations, and Cr 2O 3. On SS 441, reaction of phosphorus with (Mn,Cr) 3O 4 led to the formation of manganese phosphate as well as an Fe-P product, predicted from thermochemical calculations to be Fe 3P. Minimal interactions with antimony or arsenic in synthesis gas were limited to Fe-Sb and Fe-As solid solution formation. Though not intended for use on the anode side, a (Mn,Co) 3O 4 spinel coating on Crofer 22 APU reacted with phosphorus in synthesis gas to produce products consistent with Mn 3(PO 4) 2 and Co 2P. A thin Cr 2O 3 passivation layer on Inconel 600 did not prevent the formation of nickel phosphides and arsenides and of iron phosphides and arsenides, though no reaction with Cr 2O 3 was apparent. On alumel, an Al 2O 3 passivation layer rich in Ni did not prevent the formation of nickel phosphides, arsenides, and antimonides, though no reaction with Al 2O 3 occurred. This work shows that unprotected metallic components of an SOFC stack and system can provide a sink for P, As and Sb impurities that may be present in fuel gases, and thus complicate

  14. Materials growth and characterization of thermoelectric and resistive switching devices

    Science.gov (United States)

    Norris, Kate J.

    erbium monoantimonide (ErSb) thin films with thermal conductivities close to or slightly smaller than the alloy limit of the two ternary alloy hosts. Second we consider an ex-situ monitoring technique based on glancing-angle infrared-absorption used to determine small amounts of erbium antimonide (ErSb) deposited on an indium antimonide (InSb) layer, a concept for thermoelectric devices to scatter phonons. Thirdly we begin our discussion of nanowires with the selective area growth (SAG) of single crystalline indium phosphide (InP) nanopillars on an array of template segments composed of a stack of gold and amorphous silicon. Our approach enables flexible and scalable nanofabrication using industrially proven tools and a wide range of semiconductors on various non-semiconductor substrates. Then we examine the use of graphene to promote the growth of nanowire networks on flexible copper foil leading to the testing of nanowire network devices for thermoelectric applications and the concept of multi-stage devices. We present the ability to tailor current-voltage characteristics to fit a desired application of thermoelectric devices by using nanowire networks as building blocks that can be stacked vertically or laterally. Furthermore, in the study of our flexible nanowire network multi-stage devices, we discovered the presence of nonlinear current-voltage characteristics and discuss how this feature could be utilized to increase efficiency for thermoelectric devices. This work indicates that with sufficient volume and optimized doping, flexible nanowire networks could be a low cost semiconductor solution to our wasted heat challenge. Resistive switching devices are two terminal electrical resistance switches that retain a state of internal resistance based on the history of applied voltage and current. The occurrence of reversible resistance switching has been widely studied in a variety of material systems for applications including nonvolatile memory, logic circuits, and

  15. Mid-Infrared Reflectance Imaging of Thermal-Barrier Coatings

    Science.gov (United States)

    Edlridge, Jeffrey I.; Martin, Richard E.

    2009-01-01

    An apparatus for mid-infrared reflectance imaging has been developed as means of inspecting for subsurface damage in thermal-barrier coatings (TBCs). The apparatus is designed, more specifically, for imaging the progression of buried delamination cracks in plasma-sprayed yttria-stabilized zirconia coatings on turbine-engine components. Progression of TBC delamination occurs by the formation of buried cracks that grow and then link together to produce eventual TBC spallation. The mid-infrared reflectance imaging system described here makes it possible to see delamination progression that is invisible to the unaided eye, and therefore give sufficiently advanced warning before delamination progression adversely affects engine performance and safety. The apparatus (see figure) includes a commercial mid-infrared camera that contains a liquid-nitrogen-cooled focal plane indium antimonide photodetector array, and imaging is restricted by a narrow bandpass centered at wavelength of 4 microns. This narrow wavelength range centered at 4 microns was chosen because (1) it enables avoidance of interfering absorptions by atmospheric OH and CO2 at 3 and 4.25 microns, respectively; and (2) the coating material exhibits maximum transparency in this wavelength range. Delamination contrast is produced in the midinfrared reflectance images because the introduction of cracks into the TBC creates an internal TBC/air-gap interface with a high diffuse reflectivity of 0.81, resulting in substantially higher reflectance of mid-infrared radiation in regions that contain buried delamination cracks. The camera is positioned a short distance (.12 cm) from the specimen. The mid-infrared illumination is generated by a 50-watt silicon carbide source positioned to the side of the mid-infrared camera, and the illumination is collimated and reflected onto the specimen by a 6.35-cm-diameter off-axis paraboloidal mirror. Because the collected images are of a steady-state reflected intensity (in

  16. Laser-based sensors on UAVs for quantifying local emissions of greenhouse gases

    Science.gov (United States)

    Zondlo, Mark; Tao, Lei; O'Brien, Anthony; Ross, Kevin; Khan, Amir; Pan, Da; Golston, Levi; Sun, Kang; DiGangi, Josh

    2015-04-01

    well above the surface (up to 100 m). In addition, plumes were very narrow horizontally (10-30 m width) within 200 m of the emission origin. By using a mass balance approach of upwind versus downwind CH4 concentrations, coupled to meteorological wind data, the CH4 emission rate from the compressor station averaged 13 ± 5 g CH4 s-1, consistent with individual, leak surveys measured within the compressor station itself. More recently, we developed a mid-infrared version of the same sensor using an antimonide laser at 3.3 microns. This sensor has a precision of 2 ppbv CH4 at 10 Hz, a mass of 1.3 kg, and consumes 10 W of power. Flight tests show the improved precision is capable of detecting methane leaks from landfills and cattle feedlots at higher altitudes (500 m) and greater distances downwind (several km) than the near infrared CH4 sensor. Sampling strategy is particularly important for not only UAS-based flight patterns but also sensor design. Many tradeoffs exist between the sampling density of the flight pattern, sensor precision, accuracy of wind data, and geographic isolation of the source of interest, and these will be discussed in the context of airborne-based CH4 measurements in the field. The development of compact yet robust trace gas sensors to be deployed on small UAS opens new capabilities for atmospheric sensing such as quantifying local source emissions (e.g. farms, well pads), vertical profiling of trace gases in a forest canopy, and trace gas distributions in complex areas (mountains, urban canyons).

  17. Development of III-Sb based technologies for p-channel MOSFET in CMOS applications

    Science.gov (United States)

    Madisetti, Shailesh Kumar

    --V characteristics with a similarly low Dit˜1--2x1012 cm 2eV-1 were demonstrated without IPL. Next, biaxial compressive strain on InxGa1-xSb quantum wells were studied by varying In composition and studying Hall mobility to understand major scattering mechanisms in surface and buried MBE grown strained InGaSb quantum well (QW) MOSFET channels with in-situ grown Al 2O3 gate oxide are analyzed as a function of sheet hole density, top-barrier thickness and temperature. Mobility dependence on Al0.8Ga 0.2Sb top-barrier thickness shows that the relative contribution of interface-related scattering is as low as ˜30% in the surface QW channel. An InAs top capping layer reduces the interface scattering even further; the sample with 3 nm total top-barrier thickness demonstrates mobility of 980 cm2/Vs giving sheet resistance of 4.3 kO/sq, very close to the minimum QW resistance in the bulk. The mobility--temperature dependences indicate that the interface-related scattering is dominated by remote Coulomb scattering at hole densities silicon has been studied with the goal to improve the quality of group III-antimonide heteroepitaxial materials for III-Sb CMOS to assess various metamorphic buffer layer technologies, evaluate baseline for density of related defects and surface morphology, uncover their effect on electrical properties, provide baseline for futuristic growth of III-V integration on a common platform.

  18. Material Engineering for Phase Change Memory

    Science.gov (United States)

    Cabrera, David M.

    As semiconductor devices continue to scale downward, and portable consumer electronics become more prevalent there is a need to develop memory technology that will scale with devices and use less energy, while maintaining performance. One of the leading prototypical memories that is being investigated is phase change memory. Phase change memory (PCM) is a non-volatile memory composed of 1 transistor and 1 resistor. The resistive structure includes a memory material alloy which can change between amorphous and crystalline states repeatedly using current/voltage pulses of different lengths and magnitudes. The most widely studied PCM materials are chalcogenides - Germanium-Antimony-Tellerium (GST) with Ge2Sb2Te3 and Germanium-Tellerium (GeTe) being some of the most popular stochiometries. As these cells are scaled downward, the current/voltage needed to switch these materials becomes comparable to the voltage needed to sense the cell's state. The International Roadmap for Semiconductors aims to raise the threshold field of these devices from 66.6 V/mum to be at least 375 V/mum for the year 2024. These cells are also prone to resistance drift between states, leading to bit corruption and memory loss. Phase change material properties are known to influence PCM device performance such as crystallization temperature having an effect on data retention and litetime, while resistivity values in the amorphous and crystalline phases have an effect on the current/voltage needed to write/erase the cell. Addition of dopants is also known to modify the phase change material parameters. The materials G2S2T5, GeTe, with dopants - nitrogen, silicon, titanium, and aluminum oxide and undoped Gallium-Antimonide (GaSb) are studied for these desired characteristics. Thin films of these compositions are deposited via physical vapor deposition at IBM Watson Research Center. Crystallization temperatures are investigated using time resolved x-ray diffraction at Brookhaven National Laboratory

  19. Analysis of Structural Stress in InSb Array Detector without Underfill

    Directory of Open Access Journals (Sweden)

    Qingduan Meng

    2012-08-01

    Full Text Available Hybrid infrared focal plane arrays (IRFPAs are more and more used in both infrared medium and long wavebands for many different applications. In order to offer more spatial resolution, larger format (2048×2048 start to be available, yet its final yield is so low that its cost is very high, and is not affordable. In this paper, basing on viscoplastic Anand’s model, the structural stress of indium antimonide (InSb infrared focal plane arrays detector without underfill dependent on both indium bump sizes and array formats is systematically researched by finite element method. For shortening simulation time, three-step method is employed to research Von Mises stress and its distribution in InSb infrared focal plane arrays. First, the structural stress of 8×8 InSb infrared focal plane arrays detector is systematically analyzed by finite element method, and the impacts of design structural parameters including indium bump diameters, heights and InSb chip thicknesses on both Von Mises stress and its distribution are discussed in this manuscript. Simulation results show that as the diameters of indium bump decreases from 36µm to 24µm in step of 2µm, the maximum stress existing in InSb chip firstly reduces, then increases linearly with reduced indium bump diameters, and reaches minimum with indium bump diameter 30µm, the stress distribution at the contacts areas is uniform and concentrated. Furthermore, it seems that the varied tendency has nothing to do with indium bump standoff height. With indium bump diameter 30 µm, as the thickness of InSb chip reduces from 21µm to 9µm in step of 3µm, the varying tendency of the maximum stress value in InSb chip is just like the letter U, as the indium bump thickness decreases also from 21µm to 6µm in step of 3µm, the maximum stress in 8×8 InSb IRPFAs decreases from 260MPa to 102MPa, which is the smallest Von Mises stress value obtained with the indium diameter 30µm, thickness 9µm and In