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. 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...

  3. Near atomically smooth alkali antimonide photocathode thin films

    CERN Document Server

    Feng, Jun; Nasiatka, James; Schubert, Susanne; Smedley, John; Padmore, Howard

    2016-01-01

    Nano-roughness limits the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. However there is an urgent need for photocathodes that can produce an order of magnitude or more lower emittance than present day systems in order to increase the transverse coherence width of the electron beam. In this paper we demonstrate a method for producing alkali antimonide cathodes with near atomic smoothness with high reproducibility.

  4. Indium antimonide based HEMT for RF applications

    Institute of Scientific and Technical Information of China (English)

    T.D.Subash; T.Gnanasekaran

    2014-01-01

    We report on an indium antimonide high electron mobility transistor with record cut-off frequency characteristics.For high frequency response it is important to minimize parasitic resistance and capacitance to improve short-channel effects.For analog applications adequate pinch-off behavior is demonstrated.For proper device scaling we need high electron mobility and high electron density.Toward this end,the device design features and simulation are carried out by the Synopsys TCAD tool.A 30 nm InSb HEMT exhibits an excellent cut-off frequency of 586 GHz.To the knowledge of the authors,the obtained cut-off frequency is the highest ever reported in any FET on any material system.

  5. Indium Antimonide Nanowires: Synthesis and Properties

    Science.gov (United States)

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

    2016-03-01

    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.

  6. Kinetic Study of MOCVD Ⅲ-Ⅴ Quaternary Antimonides

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The kinetics of MOCVD GaInAsSb and AlGaAsSb was studied by the growth rate as a function of growth temperature and partial pressure of Ⅲ and Ⅴ MO species. The diffusion theory was used to explain the mass transport processes in MOCVD Ⅲ-Ⅴ quaternary antimonides. On the basis of the discussion about their growth kinetics and epilayer properties, the good quality multi-epilayers of these two quaternary antimonides and their photodetectors and arrays with wavelength of 1.8~2.3 μm and detectivities of D*>109 cm Hz1/2 W-1 were obtained.

  7. Low temperature solution synthesis of zinc antimonide, manganese antimonide, and strontium ruthenate compounds

    Science.gov (United States)

    Noblitt, Jennifer Lenkner

    2011-12-01

    Increasing energy demands are fueling research in the area of renewable energy and energy storage. In particular, Li-ion batteries and superconducting wires are attractive choices for energy storage. Improving safety, simplifying manufacturing processes, and advancing technology to increase energy storage capacity is necessary to compete with current marketed energy storage devices. These advancements are accomplished through the study of new materials and new morphologies. Increasing dependence on and rising demand for portable electronic devices has continued to drive research in the area of Li-ion batteries. In order to compete with existing batteries and be applicable to future energy needs such as powering hybrid vehicles, the drawbacks of Li-ion batteries must be addressed including (i) low power density, (ii) safety, and (iii) high manufacturing costs. These drawbacks can be addressed through new materials and morphologies for the anode, cathode, and electrolyte. New intermetallic anode materials such as ZnSb, MnSb, and Mn2Sb are attractive candidates to replace graphite, the current industry standard anode material, because they are safer while maintaining comparable theoretical capacity. Electrodeposition is an inexpensive method that could be used for the synthesis of these electrode materials. Direct electrodeposition allows for excellent electrical contact to the current collector without the use of a binder. To successfully electrodeposit zinc and manganese antimonides, metal precursors with excellent solubility in water were needed. To promote solubility, particularly for the antimony precursor, coordinating ligands were added to the deposition bath solutions. This work shows that the choice of coordinating ligand and metal-ligand speciation can alter both the electrochemistry and the film composition. This work focuses on the search for appropriate coordinating ligands, solution pH, and bath temperatures so that high quality films of ZnSb, MnSb, and

  8. 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.)

  9. Power Generation by Zinc Antimonide Thin Film under Various Load Resistances at its Critical Operating Temperature

    DEFF Research Database (Denmark)

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

    Thermoelectric generators (TEGs) use the Seebeck effect in semiconductors for direct conversion of heat to electrical energy. Zinc antimonide films were deposited on polished fused silica substrates by co-sputtering method in Aarhus University. This study focuses on stability of zinc antimonide...... thin films operating under different load resistances at around its critical operating temperature, 400 ᵒC. The thermoelement is subjected to constant hot side temperature and to room temperature at the cold junction in order to measure the thin film TEG’s sample performance. The nominal loads equal...... to 10, 15, 20, 25, 30, 35, 40, 45… 175, and also 200 Ohms were applied. The results show that the value of the Seebeck coefficient is 0.0002 [V/K] for the specimen, which is in agreement with quantities of other zinc antimonide bulks materials in literature. The results also show that the voltage...

  10. 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.

  11. 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.

  12. 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...

  13. 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...

  14. 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.

  15. 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.

  16. 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.

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

    Science.gov (United States)

    Wassweiler, Ella; Toor, Fatima

    2016-06-01

    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.

  18. 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.

  19. Electrochemical properties of some cobalt antimonides as anode materials for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xinbing; CAO Gaoshao; ZHANG Lijuan; XIE Jian

    2003-01-01

    Some cobalt antimonides have been prepared and studied as the candidate anode materials for lithium ion batteries. Reversible capacities of 424, 423 and 546 mA@h@g -1 were measured at the first cycle for as-solidified CoSb2, CoSb3 and annealed CoSb3 respectively. A low lithium ions diffusion coefficient in the order of 10-16 m 2@s -1 was estimated from the coulometric titration measurements in the annealed CoSb3 electrode. It was found that the electrochemical properties of fine powders are significantly better than coarse powders. However the SEM picture shows that the nano-sized CoSb3powders gathered to larger granules, which worsens somewhat the capacity retention of the nano-sized materials, although the volume capacities of the annealed and ball milled CoSb3 remain near twice of that of graphite after 50 cycles.

  20. Defect reactions in gallium antimonide studied by zinc and self-diffusion

    Science.gov (United States)

    Sunder, Kirsten; Bracht, Hartmut

    2007-12-01

    Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. It is concluded that the changeover of interstitial Zn to substitutional gallium (Ga) sites is mainly mediated by Ga interstitials ( IGa). Fitting of the Zn profiles provides the relative contributions of IGa to Ga diffusion. This contribution is lower than the directly measured Ga diffusion coefficient indicating that Ga diffusion in GaSb is rather mediated by Ga vacancies than by Ga interstitials even under Ga-rich conditions. This finding supports transformation reactions between native point defects that are confirmed by first-principles total-energy calculations. In addition Ga and Sb diffusion experiments under H22 atmosphere were performed to reconcile the controversial data on self-diffusion in GaSb published by Weiler et al. and Bracht et al.

  1. Structural, elastic, electronic and optical properties of bi-alkali antimonides

    Indian Academy of Sciences (India)

    G MURTAZA; MAZHAR ULLAH; NAEEM ULLAH; MALIKA RANI; M MUZAMMIL; R KHENATA; SHAHID M RAMAY; UMAIR KHAN

    2016-10-01

    The structural parameters, elastic constants, electronic and optical properties of the bi-alkali antimonides (Na$_2$KSb, Na$_2$RbSb, Na$_2$CsSb, K$_2$RbSb, K$_2$CsSb and Rb$_2$CsSb) were calculated using state-of-the-art density functional theory. Different exchange-correlation potentials were adopted to predict the physical properties of these compounds. The calculated structural parameters are found in good agreement with the available experimental and theoretical results. All the compounds are mechanically stable. The compounds Na$_2$KSb, K$_2$RbSb, K$_2$CsSb and Rb$_2$CsSb have direct bandgaps, in which chemical bonding among the cations and anions is mainly ionic. Furthermore, the optical properties of these compounds are described in detail in terms of the dielectric function, refractive index, reflectivity, optical conductivity and absorption coefficient.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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...

  7. Nonlinear radiation response of n-doped indium antimonide and indium arsenide in intense terahertz field

    Science.gov (United States)

    Gong, Jiao-Li; Liu, Jin-Song; Chu, Zheng; Yang, Zhen-Gang; Wang, Ke-Jia; Yao, Jian-Quan

    2016-10-01

    The nonlinear radiation responses of two different n-doped bulk semiconductors: indium antimonide (InSb) and indium arsenide (InAs) in an intense terahertz (THz) field are studied by using the method of ensemble Monte Carlo (EMC) at room temperature. The results show that the radiations of two materials generate about 2-THz periodic regular spectrum distributions under a high field of 100 kV/cm at 1-THz center frequency. The center frequencies are enhanced to about 7 THz in InSb, and only 5 THz in InAs, respectively. The electron valley occupancy and the percentage of new electrons excited by impact ionization are also calculated. We find that the band nonparabolicity and impact ionization promote the generation of nonlinear high frequency radiation, while intervalley scattering has the opposite effect. Moreover, the impact ionization dominates in InSb, while impact ionization and intervalley scattering work together in InAs. These characteristics have potential applications in up-convension of THz wave and THz nonlinear frequency multiplication field. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574105 and 61177095), the Natural Science Foundation of Hubei Province, China (Grant Nos. 2012FFA074 and 2013BAA002), the Wuhan Municipal Applied Basic Research Project, China (Grant No. 20140101010009), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 2013KXYQ004 and 2014ZZGH021).

  8. 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.

  9. 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

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

    Science.gov (United States)

    Zamiri, M.; Klein, B.; Schuler, T.; Myers, S.; Cavallo, F.; Krishna, S.

    2016-05-01

    We present an approach to realize antimonide based superlattices on silicon substrates without using conventional Indium-bump hybridization. In this approach, PIN based superlattice detectors 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 epitaxiallift 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.

  11. 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.)

  12. Time-resolved X-ray diffraction at monocrystalline indium antimonide; Zeitaufgeloeste Roentgenbeugung an einkristallinem Indiumantimonid

    Energy Technology Data Exchange (ETDEWEB)

    Hoefer, Sebastian

    2014-11-07

    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 8.10{sup 16} W/cm{sup 2}), 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. [German] Die vorliegende Arbeit behandelt die experimentelle Untersuchung der strukturellen Aenderung des Halbleiters Indiumantimonid (InSB) nach der Anregung durch einen ultrakurzen Laserpuls (60 fs). Die Untersuchung erfolgt durch ultrakurze Roentgenpulse (rund 100 fs). Als Quelle der ultrakurzen Roentgenpulse dient eine Laser-Plasma Roentgenquelle. Bei dieser Quelle wird ein ultrakurzer intensiver optischer Laserpuls auf eine Metallfolie fokussiert (Intensitaet bis 8.10{sup 16} W/cm{sup 2}), durch das entstehende Plasma kommt es zu einer Emission von Roentgenstrahlung. Zur Charakterisierung der Roentgenquelle stand ein neuartiger Timepix- Detektor zu Verfuegung, der

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

    Energy Technology Data Exchange (ETDEWEB)

    Yaduvanshi, Namrata, E-mail: namrata-yaduvanshi@yahoo.com; Kapoor, Shilpa; Singh, Sadhna [High Pressure Research Lab. Department of Physics, Barkatullah University, Bhopal (M.P.) India-462026 (India)

    2015-05-15

    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 (TBIPE{sub P}). These compounds exhibit first order crystallographic phase transition from NaCl (B{sub 1}) to CsCl (B{sub 2}) 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 (TBIPE{sub P}) show a good agreement with available experimental data.

  14. 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.

  15. 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.

  16. 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)

  17. 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

  18. A study of the preparation of epitaxy-ready polished surfaces of (100) Gallium Antimonide substrates demonstrating ultra-low surface defects for MBE growth

    Science.gov (United States)

    Martinez, Rebecca; Tybjerg, Marius; Flint, Patrick; Fastenau, Joel; Lubyshev, Dmitri; Liu, Amy W. K.; Furlong, Mark J.

    2016-05-01

    Gallium Antimonide (GaSb) is an important Group III-V compound semiconductor which is suitable for use in the manufacture of a wide variety of optoelectronic devices such as infra-red (IR) focal plane detectors. A significant issue for the commercialisation of these products is the production of epitaxy ready GaSb, which remains a challenge for the substrate manufacturer, as the stringent demands of the MBE process, requires a high quality starting wafer. In this work large diameter GaSb crystals were grown by the Czochralski (Cz) method and wafers prepared for chemo-mechanical polishing (CMP). Innovative epi-ready treatments and novel post polish cleaning methodologies were applied. The effect of these modified finishing chemistries on substrate surface quality and the performance of epitaxially grown MBE GaSb IR detector structures were investigated. Improvements in the lowering of surface defectivity, maintaining of the surface roughness and optimisation of all flatness parameters is confirmed both pre and post MBE growth. In this paper we also discuss the influence of bulk GaSb quality on substrate surface performance through the characterisation of epitaxial structures grown on near zero etch pit density (EPD) crystals. In summary progression and development of current substrate polishing techniques has been demonstrated to deliver a consistent improved surface on GaSb wafers with a readily desorbed oxide for epitaxial growth.

  19. 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.)

  20. 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.)

  1. Synthesis and characterisation of (poly-)antimonides and N-doped ZnO; Synthese und Charakterisierung von (Poly-)antimoniden und die Darstellung von N-dotiertem ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Greiwe, Magnus Josef Benedikt

    2014-06-16

    }Sb{sub y} (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 with partial Fe or Ni substitution were prepared. Cr{sub 2}Ni{sub 0,3}Sb{sub 3,7} was tested as potential anodic material and a capacity of 98% (520 mAh.g{sup -1}) of the theoretical capacity in the 2{sup nd} cycle was measured. All compounds indicated that antimonies with a covalent bonding character are more stable against lithium intercalation than the intermetallic ones. New compounds in the quaternary system Cu-Hg-Sb-X (X = Br, I) were obtained by using the reaction conditions for the earlier (lighter) elements of the V. main group (P, As). In the new structure [Hg{sub 3}Sb{sub 2}]{sub 4}[CuX{sub 3}]{sub 4}X{sub 2} (X = Br, I) X{sub 2} a barbell of the halide is present. This structure is the first example in the system Hf-Sb-X which shows two different interpenetrated networks: [Hg{sub 3}Sb{sub 2}]{sup 2+} and [CuX{sub 3}]{sup 2-}. For the first time it has been possible to calculate the Br-Br bond length by X-ray single crystal measurements at room temperature. Another topic of this work was to test the solution combustion method (SCM) in order to gain ZnO (Wurtzit structure) with nitrogen defects at the oxygen position. Standard synthesis methods for oxonitrides require high temperature or high pressure procedures. A softer synthesis method is the solution combustion method published by Mapa and Gopinath. The results of various experiments in cooperation with Stefan Soellradl yielded no intercalation of nitrogen defects into ZnO but a new phase was found which is identified as isocyanuric acid after reprocessing.

  2. 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.

  3. Antimonide based devices for thermophotovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Hitchcock, C.W.; Gutmann, R.J.; Borrego, J.M.; Bhat, I.B. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Integrated Electronics and Electronics Manufacturing; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

    1998-12-01

    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. 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. Diffused junction devices using quasi-binary substrates offer the possibility of good performance and low manufacturing cost.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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...

  9. 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.

  10. Structural features of indium antimonide quantum dots on the indium arsenide substrate

    Directory of Open Access Journals (Sweden)

    Liliya A. Sokura

    2015-06-01

    Full Text Available The properties of InSb/InAs quantum dots (QDs have been investigated by transmission electron microscopy (TEM. Specific features of diffraction contrast were discovered in plan-view TEM images of big (9–10 nm in height and 38–50 nm in diameter InSb QDs. To understand the origin of such distortions, a model of an InSb QD on InAs substrate containing a partial Frank dislocation (FD was developed and used for calculations of the displacement field and the subsequent diffraction image simulation of an InSb QD for the first time. The shape of the QD was established to have an insignificant influence on the magnitude of radial displacements. The insertion of a misfit defect (a partial Frank dislocation into the QD reduces the strain at the edges of the QD almost by 30%. The comparison of experimental and simulated data allowed us to explain the observed features of the moiré pattern in the image of a big InSb QD by the presence of a misfit defect at the QD-substrate interface.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  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. 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.

  19. 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.

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

    Science.gov (United States)

    Wistey, Mark Allan

    Fiber optics has revolutionized long distance communication and long haul networks, allowing unimaginable data speeds and noise-free telephone calls around the world for mere pennies per hour at the trunk level. But the high speeds of optical fiber generally do not extend to individual workstations or to the home, in large part because it has been difficult and expensive to produce lasers which emitted light at wavelengths which could take advantage of optical fiber. One of the most promising solutions to this problem is the development of a new class of semiconductors known as dilute nitrides. Dilute nitrides such as GaInNAs can be grown directly on gallium arsenide, which allows well-established processing techniques. More important, gallium arsenide allows the growth of vertical-cavity surface-emitting lasers (VCSELs), which can be grown in dense, 2D arrays on each wafer, providing tremendous economies of scale for manufacturing, testing, and packaging. Unfortunately, GaInNAs lasers have suffered from what has been dubbed the "nitrogen penalty," with high thresholds and low efficiency as the fraction of nitrogen in the semiconductor was increased. This thesis describes the steps taken to identify and essentially eliminate the nitrogen penalty. Protecting the wafer surface from plasma ignition, using an arsenic cap, greatly improved material quality. Using a Langmuir probe, we further found that the nitrogen plasma source produced a large number of ions which damaged the wafer during growth. The ions were dramatically reduced using deflection plates. Low voltage deflection plates were found to be preferable to high voltages, and simulations showed low voltages to be adequate for ion removal. The long wavelengths from dilute nitrides can be partly explained by wafer damage during growth. As a result of these studies, we demonstrated the first CW, room temperature lasers at wavelengths beyond 1.5mum on gallium arsenide, and the first GaInNAs(Sb) VCSELs beyond 1.31mum: 1.46mum. These techniques offer the promise of inexpensive, high speed fiber networking.

  1. Theoretical Design and Material Growth of Type-II Antimonide-based Superlattices for Infrared Detection and Imaging

    Science.gov (United States)

    Nguyen, Binh-Minh

    The goal of this PhD thesis is to investigate quantum properties of the superlattice system, design appropriate device architectures and experimentally fabricate infrared detectors which can outperform currently existing devices. In parallel, efforts in material growth using molecular beam epitaxy (MBE) have resulted in higher material quality and vastly improved growth conditions of III-V compounds as compared to previous work. Superlattices as thick as 15mum were realized without growth defects or dislocations, narrow X-ray diffraction peaks and small surface roughness. Many ternary and quaternary layers such as InAsSb, AlAsSb, GaAlAsSb were routinely used in new design architectures to enhance the electrical performance of the devices. Advances in theoretical calculations and material growth have allowed this work to continue with comprehensive studies of photodetector device architectures. Fundamental parameters affecting the performance of infrared detectors were investigated. We have experimentally pointed out the difference in the collection of photocurrent generated in the n-type and p-type regions. By forcing the device's active region to have an appropriate p-doped concentration, and by assuring long diffusion carrier lengths with high material quality, the quantum efficiency of Type-II superlattice photodiodes have been demonstrated in excess 50% in front side illumination configuration and 75% in back side illumination configuration. In an attempt to optimize the electrical performance, basic mechanisms of the dark current have been thoroughly analyzed. By intentionally doping the active region, the diffusion and generation-recombination currents were reduced until they were overwhelmed by the tunneling current. The device performance was then further enhanced due to the suppression of the tunneling current using the hetero-design of the M-structure superlattice. This optimization scheme can be repeated iteratively to lower all bulk-components of the dark current until the device performance is dominated by the surface component. The results of this thesis' work show that the design and material quality of bulk Type-II-superlattice is thus not a limiting factor for optimal device performance. Further employment of the M-structure superlattice has resulted in a novel device architecture called the pMp design. This novel device is a hybrid between conventional photoconductive and photovoltaic detectors. Profiting from the advantages of its parents' configurations, the pMp design has shown numerous advantageous for infrared detections such as low generation-recombination current, suppressed tunneling current, and reduced surface leakage while keeping high optical efficiency of the detectors based on long-diffusion-length minority electrons. This design can also be used as a simple architecture for bias-selectable dual color detection which is proven to mitigate the difficulties of both the material growth and the device fabrication. In addition to improving the performance of single element detectors, this work also contributed to the successful demonstration of focal plane arrays at the Center for Quantum Devices. For the first time, the polarity of Type-II photodiodes has been matched with the requirement of commercially available Read Out Integrated Circuits (ROICs) through the realization of n-type InAsSb This polarity matching has significantly improved the imaging quality because it allows the bias and carrier types to be correctly utilized. Furthermore, attempts on 3" in diameter superlattice growth wafer were made, which resulted in excellent material uniformity across the whole wafer. Finally, targetting "color" imaging, different sophisticated architectures for dual spectral detection were demonstrated, in which each channel exhibited similar performance as that of single element detectors. (Abstract shortened by UMI.)

  2. 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.

  3. 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.

  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.

  5. 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

  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. Shubnikov-de Haas Oscillations in a Degenerate Semiconductor.

    Science.gov (United States)

    Mansfield, R.

    1978-01-01

    Describes an experiment, in solid-state physics, for measuring the Shubnikov-de Haas oscillations in indium antimonide. It also provides an introduction to low-temperature techniques and to cryomagnetic systems. (Author/GA)

  8. 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

  9. Upconversion imager measures single mid-IR photons

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2013-01-01

    The most sensitive IR detectors today are based on exotic semicoductor technology such as indium antimonide or mercury cadmium telluride. High quality detectors of these sorts are expensive and suffer from high dark currents. Dark current can be somewhat alleviated by extreme cooling. Comparing t...

  10. The Local Electron Scattering on the Lattice Defects in InSb and InN

    Directory of Open Access Journals (Sweden)

    O.P. Malyk

    2016-06-01

    Full Text Available In proposed paper the interaction of electrons with lattice defects characterized by the potential of the limited action radius in indium antimonide and nitride crystals is considered. The dopant concentration in observed n-InSb crystals was (1÷ 8 × 1014 cm – 3 and in n-InN sample ≈ 6 × 1017 cm – 3. In the framework of the analytical solution of the stationary kinetic Boltzmann equation using the short-range principle the temperature dependences of electron mobility, Hall factor and thermoelectric power in indium antimonide in the temperature range 8-700 K are calculated. For indium nitride crystal the temperature dependences of electron mobility and Hall factor in the interval 4.2-560 K are presented.

  11. 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.

  12. 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.

  13. Report of high quantum efficiency photocathode at Milano

    Energy Technology Data Exchange (ETDEWEB)

    Michelato, P. (INFN and University of Milano, Lab. LASA, Via F.lli Cervi 201, 2009, Segrate (Georgia))

    1992-07-01

    R D activity on high quantum efficiency alkali antimonide photocathode is in progress at Milano, in the context of the ARES program. Inside a preliminary preparation chamber, Cs[sub 3]Sb layers with qunatum efficiency up to 9% (at [lambda]=543.5 nm) and lifetime of some days has been recently produced on copper, stainless steel and niobium, using a reproducible deposition procedure adapted to the material of the different substrata.

  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. 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.

  16. 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 (...

  17. Effect of Transition Metal on the Electrochemical Performances of Some Intermetallic Anodes for Lithium Ion Batteries

    Institute of Scientific and Technical Information of China (English)

    Jian XIE; Xinbing ZHAO; Gaoshao CAO; Mingjian ZHAO; Yaodong ZHONG

    2004-01-01

    Some transition metal antimonides were prepared by levitation melting and subsequent ball-milling. The electrochemical behaviors of these materials as new candidate negative electrode materials in lithium ion secondary batteries were investigated. It was found that they exhibited significantly larger volumetric capacity than carbon-based materials. The formation and composition of solid electrolyte interface (SEI) film were characterized by electrochemical impedance spectroscopy (EIS) and Fourier transform infra-red (FTIR) spectroscopy.

  18. 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.

  19. 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.

  20. 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.

  1. Charge-Injection Device (CID) Infrared Staring Imaging Sensor

    Science.gov (United States)

    Baker, W. D.; Wilson, S. H.; Missman, R. A.; Nuttall, D. E.; Ting, R. N.

    1981-07-01

    A laboratory version of an infrared staring imaging sensor, based on a 32 x 32 indium antimonide CID detector array, has been developed. That sensor serves both as a test bed for array evaluation and as a tool for investigating concepts such as non-uniformity compensation. The system is microprocessor based to provide for flexible array operation as well as for the collection and logging of array operating conditions and data. Design features of the sensor, including the focal plane and the supporting electronics, are described. Operation of the sensor is discussed and some of the imaging data collected with this system is presented.

  2. 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

  3. 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)

  4. 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. ...

  5. 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 <10(exp -5) torr (0.0013 Pa)], Sb sublimes from their surfaces, with the result that Sb depletion layers form and advance toward their interiors. As the depletion layer advances in a given device, the change in stoichiometry diminishes the thermal-to-electric conversion efficiency of the device. The problem, then, is to prevent sublimation, or at least reduce it to an acceptably low level. In preparation for an experiment on suppression of sublimation, a specimen of CoSb3 was tightly wrapped in a foil of 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 <10(exp -5) torr (0.0013 Pa), then cooled and sectioned. Examination of the sectioned specimen revealed that no depletion layer had formed, indicating the niobium foil prevented sublimation of antimony at 700 C

  6. 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

  7. An Innovative Gas Sensor with On-Chip Reference Using Monolithic Twin Laser

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Gang; TIAN Zhao-Bing; ZHANG Xiao-Jun; GU Yi; LI Ai-Zhen; ZHU Xiang-Rong; ZHENG Yan-Lan; LIU Sheng

    2007-01-01

    An innovative gas sensor with on-chip reference using a monolithic twin laser is proposed. In this sensor a monolithic twin laser generates two closer laser beams with slight different wavelengths alternatively, one photodiode is used to catch both absorption and reference signals by time division multiplexing. The detection of nitrous oxide adopting this scheme using a 2.1 μm antimonide laser and an InGaAs photodiode has been demonstrated experimentally with detection limit below 1 ppm. Using this on chip reference scheme the fluctuations from the optical path and devices can be compensated effectively; the sensor system is simplified distinctly.

  8. 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.

  9. 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...

  10. Mid-infrared tunable metamaterials

    Science.gov (United States)

    Brener, Igal; Miao, Xiaoyu; Shaner, Eric A; Passmore, Brandon Scott; Jun, Young Chul

    2015-04-28

    A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

  11. 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 ...

  12. 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...

  13. 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...

  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. 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.)

  16. 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.

  17. 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.

  18. 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.)

  19. 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.

  20. 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.).

  1. Ultra-fast dry microwave preparation of SnSb used as negative electrode material for Li-ion batteries

    Science.gov (United States)

    Antitomaso, P.; Fraisse, B.; Sougrati, M. T.; Morato-Lallemand, F.; Biscaglia, S.; Aymé-Perrot, D.; Girard, P.; Monconduit, L.

    2016-09-01

    Tin antimonide alloy was obtained for the first time using a very simple dry microwave route. Up to 1 g of well crystallized SnSb can be easily prepared in 90 s under air in an open crucible. A full characterization by X-ray diffraction and 119Sn Mössbauer spectroscopy demonstrated the benefit of carbon as susceptor, which avoid any oxide contamination. The microwave-prepared SnSb was tested as negative electrode material in Li batteries. Interesting results in terms of capacity and rate capability were obtained with up to 700 mAh/g sustained after 50 cycles at variable current. These results pave the way for the introduction of microwave synthesis as realistic route for a rapid, low cost and up-scalable production of electrode material for Li batteries or other large scale application types.

  2. Estimation of the curvature of the solid liquid interface during Bridgman crystal growth

    Science.gov (United States)

    Barat, Catherine; Duffar, Thierry; Garandet, Jean-Paul

    1998-11-01

    An approximate solution for the solid/liquid interface curvature due to the crucible effect in crystal growth is derived from simple heat flux considerations. The numerical modelling of the problem carried out with the help of the finite element code FIDAP supports the predictions of our analytical expression and allows to identify its range of validity. Experimental interface curvatures, measured in gallium antimonide samples grown by the vertical Bridgman method, are seen to compare satisfactorily to analytical and numerical results. Other literature data are also in fair agreement with the predictions of our models in the case where the amount of heat carried by the crucible is small compared to the overall heat flux.

  3. Design of a thermophotovoltaic battery substitute

    Science.gov (United States)

    Doyle, Edward F.; Becker, Frederick E.; Shukla, Kailash C.; Fraas, Lewis M.

    1999-03-01

    Many military platforms that currently use the BA-5590 primary battery or the BB-390A/U rechargeable battery are limited in performance by low storage capacity and long recharge times. Thermo Power Corporation, with team members JX Crystals and Essential Research Inc. is developing an advanced thermophotovoltaic (TPV) battery substitute that will provide higher storage capacity, lower weight, and instantaneous recharging (by refueling). The TPV battery substitute incorporates several advanced design features including: an evacuated and sealed enclosure for the emitter and PV cells to minimize unwanted convection heat transfer from the emitter to PV cells; selective tungsten emitter with a well matched gallium antimonide PV cell receiver; optical filter to recycle nonconvertible radiant energy; and a silicon carbide thermal recuperator to recover thermal energy from exhaust gases.

  4. Transition from positive to negative magnetoresistance induced by a constriction in semiconductor nanowire

    Science.gov (United States)

    Wołoszyn, M.; Spisak, B. J.; Wójcik, P.; Adamowski, J.

    2016-09-01

    We have studied the magnetotransport through an indium antimonide (InSb) nanowire grown in [111] direction, with a geometric constriction and in an external magnetic field applied along the nanowire axis. We have found that the magnetoresistance is negative for the narrow constriction, nearly zero for the constriction of some intermediate radius, and takes on positive values for the constriction with the radius approaching that of the nanowire. For all magnitudes of the magnetic field, the radius of constriction at which the change of the magnetoresistance sign takes place has been found to be almost the same as long as other geometric parameters of the nanowire are fixed. The sign reversing of the magnetoresistance is explained as a combined effect of two factors: the influence of the constriction on the transverse states and the spin Zeeman effect.

  5. 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.

  6. 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.

  7. Manipulation of adsorbed atoms and creation of new structures on room-temperature surfaces with a scanning tunneling microscope.

    Science.gov (United States)

    Whitman, L J; Stroscio, J A; Dragoset, R A; Celotta, R J

    1991-03-01

    A general method of manipulating adsorbed atoms and molecules on room-temperature surfaces with the use of a scanning tunneling microscope is described. By applying an appropriate voltage pulse between the sample and probe tip, adsorbed atoms can be induced to diffuse into the region beneath the tip. The field-induced diffusion occurs preferentially toward the tip during the voltage pulse because of the local potential energy gradient arising from the interaction of the adsorbate dipole moment with the electric field gradient at the surface. Depending upon the surface and pulse parameters, cesium (Cs) structures from one nanometer to a few tens of nanometers across have been created in this way on the (110) surfaces of gallium arsenide (GaAs) and indium antimonide (InSb), including structures that do not naturally occur.

  8. 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.)

  9. 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.

  10. 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

  11. 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)

  12. Phase dependence of secondary electron emission at the Cs-Sb-Si (111) interface

    Science.gov (United States)

    Govind, Govind; Kumar, Praveen; Shivaprasad, S. M.

    2009-06-01

    The multi-alkali antimonides adsorption on Si (111) surface has drawn much attention of several surface science studies due to its importance in both, fundamental and technological aspects of night vision devices & photocathodes. We report the formation of alkali metal antimonide ternary interface on Si(111)- 7×7 surface and in-situ characterization by X-ray Photoelectron Spectroscopy (XPS). The results show that Cs adsorption on clean Si(111) surface follows the layer-by-layer (Frank van der Merwe) growth mode at low flux rate, while Sb grows as islands (Volmer-Weber) on Cs/Si surface. The changes in the Si (2p) and Cs (3d) core level spectra show the formation of a ternary interface (Sb/Cs/Si) at room temperature, which is further confirmed by changes in the density of states in the valence band spectra. The temperature controlled desorption of ternary interface, by monitoring the chemical species remnant on the surface after annealing at different temperatures, reveal that the Sb islands desorb at 750° C, which implies a stronger Cs-Si bond to Cs-Sb bond. The work function changes from 3.9 eV to 0.8 eV for Cs adsorption on Si, which further reduces to 0.65 eV after Sb adsorption on the Cs/Si interface. The changes in work function corresponds to the compositional and chemical nature of the interface and thus indicate that the secondary electron emission is an extremely phase dependent phenomena.

  13. 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

  14. Fowler-Nordheim field emission. Effects in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Sitangshu [Indian Institute of Science, Bangalore (India). Nano Scale Device Research Laboratory; Ghatak, Kamakhya Prasad [Calcutta Univ. (India). Dept. of Electronics Science

    2012-07-01

    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, PtSb{sub 2}, stressed materials, Bismuth, GaP, Gallium Antimonide, II-V, Bi{sub 2}Te{sub 3}, 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 book can also serve as a basis for a graduate course on field emission from solids. (orig.)

  15. 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...

  16. 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.

  17. Infrared technology XIV; Proceedings of the Meeting, San Diego, CA, Aug. 15-17, 1988

    Science.gov (United States)

    Spiro, Irving J.

    1988-01-01

    Papers on IR technology are presented, covering topics such as crosstalk in closely-spaced In antimonide detectors, elevated temperature operation of InSb linear arrays, a PtSi IR imaging array, avalanche photodiodes for lidar atmospheric return signal detectors, surface leakage current in CdHgTe photodiodes, the responsivity of Si photodiodes, and spatial nonuniformity correction in a staring sensor. Other topics include a multimodule shortwave IR linear array and scene simulator, a 1-5-micron imaging camera, a HgCdTe hybrid focal plane, a dual multiplexed InSb focal plane array, aerosol effects on jet-engine IR radiation, Landsat thermal imaging, hot spot detection, linear pyroelectric arrays, a low altidue IR earth sensor. Additional subjects include an IR high-speed Fabry-Perot interferometer, IR research in Germany, eye safe lasers, In-doped Si detector arrays, rapid multispectral investigations by a compact CO2 lidar, an IR radiation model for aircraft and reentry vehicles, target classification by vibration sensing, thermal IR CCDs for space applications, and high-power solar-pumped solid-state lasers.

  18. MEASUREMENTS OF HIGH-FIELD THZ INDUCED PHOTOCURRENTS IN SEMICONDUCTORS

    Energy Technology Data Exchange (ETDEWEB)

    Wiczer, M.; Lindenberg, A.

    2008-01-01

    THz pulses have provided a useful tool for probing the time-resolved dynamics of free carriers in a system. However, the development of methods to produce intense THz radiation has been slow. We have developed a method for producing intense ultra-short THz pulses, which have a full width at half maximum of 300 fs — approximately a half cycle of THz radiation. These intense half cycle pulses (HCPs) allowed us to use THz radiation as a source of excitation. By exposing the semiconductor indium antimonide (InSb) to intense THz HCP radiation, we have observed non-linear optical effects which suggest the generation of new free carriers by below band-gap THz photons. This generation of free carriers appears to be due to an avalanche multiplication process which then induces a current in the time-scale of our THz pulse. This amplifi cation on such a short timescale suggests the possibility of an ultrafast detector of weak above band-gap radiation. We constructed a device which detects these currents by painting an electrode structure on the surface of the semiconductor. The currents induced across the electrodes by this avalanche multiplication process were measured and compared with other measurements of this non-linear optical process. We successfully measured THz induced currents in InSb, suggesting promise towards the development of an ultra-fast detector. Further, we have gained insight into a possible physical explanation of the THz induced free carriers we observe in InSb.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. Conceptual Design of 500 watt portable thermophotovoltaic power supply using JP-8 fuel

    Science.gov (United States)

    DeBellis, Crispin L.; Scotto, Mark V.; Scoles, Stephen W.; Fraas, Lewis

    1997-03-01

    Babcock & Wilcox (B&W) and JX Crystals (JXC) have developed an innovative design for a compact, 500 watt net electric (We), 24-VDC thermophotovoltaic (TPV) power supply using JP-8 fuel. As currently envisioned, the TPV generator will be approximately 20 cm (8 inches) in diameter and 50 cm (20 inches) high, not including a fuel tank and controls. The total system may weigh as little as 7.5 kg (16.5 lb) without fuel. This system will achieve high efficiency and high power density relative to its size through the use of low bandgap gallium antimonide (GaSb) PV cells and a matched emitter. A thermally integrated fuel vaporizer and recuperator will boost system efficiency by transferring the unused energy in the exhaust stream to the incoming fuel and combustion air. At rated conditions and 500 We output, the system is expected to have an overall efficiency of 8% to 10%. This paper examines the trade-offs between system efficiency, power density, and weight required in the selection and configuration of the major system components.

  5. Component development for 500 watt diesel fueled portable thermophotovoltaic (TPV) power supply

    Science.gov (United States)

    DeBellis, Crispin L.; Scotto, Mark V.; Fraas, Lewis; Samaras, John; Watson, Ron C.; Scoles, Stephen W.

    1999-03-01

    McDermott Technology, Inc. (MTI) and JX Crystals have developed an innovative design for a compact, 500-watt, thermophotovoltaic (TPV) power supply using diesel fuel. Under a contract with the Defense Advanced Research Projects Agency (DARPA) and managed by the U.S. Army Communications-Electronics Command (CECOM), this design is being reduced to hardware. Prototypes of the two main subsystems, the power converter assembly (PCA) and the burner/emitter/recuperator (BER), have been designed, fabricated, and tested. The PCA uses low-band-gap gallium antimonide (GaSb) photovoltaic (PV) cells for high efficiency and power density. The prototype PCA will be air cooled for system simplicity and portability. However, initial testing was performed on a water-cooled PCA. The BER uses a thermal vaporizer to produce a stable, high-intensity, low-emissions combustion zone inside an impervious emitter. A thermally integrated recuperator is utilized to boost system efficiency by transferring the unused energy in the exhaust stream to the incoming fuel and combustion air. This paper describes the design, testing and performance of the first-generation PCA and BER along with model predictions used for design and evaluation.

  6. GaSb film growth by liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Cruz, M.L.; Martinez-Juarez, J.; Lopez-Salazar, P. [CIDS-ICUAP, BUAP, Av. 14 Sur y San Claudio, C.U. Edif.103C, Col. Sn Manuel, C.P. 72570, Puebla, Pue. (Mexico); Diaz, G.J. [Centro de Investigacion y Estudios Avanzados, IPN, Av. IPN 2508, Col. Sn. Pedro Zacatenco, C.P. 07360, D.F. (Mexico)

    2010-04-15

    Doped GaSb (Gallium Antimonide) films on p-GaSb substrates have been obtained by means of a low-cost and fast-growth method: the liquid phase epitaxy (LPE) technique. The growth temperature was 400 C, and the growth time was varied between1 and 5 min. Characterization of the films was performed by means of high resolution X-ray Diffraction, low temperature-photoluminescence and current-voltage curve measurements. The X-ray diffraction pattern confirms a zincblende-type crystal structure with a high-thin peak centred at 30.36 . The PL spectra at 27 K allowed to confirm the band-gap energy to be 0.8 eV and the I-V curves presented a PN junction behavior which corresponds to the obtained structured. Metal contacts of Au-Zn and Au-Ge were placed to perform electrical characterization (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. 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...

  8. Electrochemical, structural and surface characterization of nickel/zirconia solid oxide fuel cell anodes in coal gas containing antimony

    Science.gov (United States)

    Marina, Olga A.; Pederson, Larry R.; Coyle, Christopher A.; Thomsen, Edwin C.; Nachimuthu, Ponnusamy; Edwards, Danny J.

    The interactions of antimony with the nickel-zirconia anode in solid oxide fuel cells (SOFCs) have been investigated. Tests with both anode-supported and electrolyte-supported button cells were performed at 700 and 800 °C in synthetic coal gas containing 100 ppb to 9 ppm antimony. Minor performance loss was observed immediately after Sb introduction to coal gas resulting in ca. 5% power output drop. While no further degradation was observed during the following several hundred hours of testing, cells abruptly and irreversibly failed after 800-1600 h depending on Sb concentration and test temperature. Antimony was found to interact strongly with nickel resulting in extensive alteration phase formation, consistent with expectations based on thermodynamic properties. Nickel antimonide phases, NiSb and Ni 5Sb 2, were partially coalesced into large grains and eventually affected electronic percolation through the anode support. Initial degradation was attributed to diffusion of antimony to the active anode/electrolyte interface to form an adsorption layer, while the late stage degradation was due the Ni-Sb phase formation. Assuming an average Sb concentration in coal gas of 0.07 ppmv, a 500 μm thick Ni/zirconia anode-supported cell is not expected to fail within 7 years when operated at a power output of 0.5 W cm -2 and fuel utilization above 50%.

  9. 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...

  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. 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.

  12. 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...

  13. 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.

  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. 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.)

  16. High spatial resolution Hall sensor array for edge plasma magnetic field measurements

    Science.gov (United States)

    Liu, Yuhong; Maurer, David A.; Navratil, Gerald A.; Rivera, Nicholas

    2005-09-01

    A one-dimensional, high-spatial resolution, 20-element Hall sensor array has been developed to directly measure the edge plasma perpendicular magnetic field and its fluctuations as a function of radius with 4-mm resolution. The array employs new small-area, high-sensitivity indium antimonide (InSb) Hall probes in combination with a high-density seven-layer printed circuit board to provide for connections to supply Hall current, record the measured Hall voltage output signals, and mitigate inductive pickup. A combination of bench and in situ measurements is described that provides absolute calibration of the diagnostic array in the presence of a strong transverse magnetic field component that is approximately 1000 times greater than the perpendicular fluctuating field needed to be resolved by the diagnostic. The Hall probes calibrated using this method are capable of magnetic field measurements with a sensitivity of 7V/T over the frequency band from 0 to 20 kHz.

  17. 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.

  18. 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.

  19. Characterization of Cs-Sb cathodes for high charge RF photoinjectors

    CERN Document Server

    AUTHOR|(CDS)2082505; Beghi, Marco

    Future accelerators such as CLIC (Compact LInear Collider), require high brightness electron beams that could be produced with a photoinjector (laser-driven electron source). Cs2Te photocathodes in combination with ultra-violet (UV) laser beams are currently used in many photoinjector facilities, but requirements to the electron sources for future accelerators like CLIC are more demanding. The main challenge for the CLIC drive beam photoinjector is to achieve high bunch charges (8.4 nC), high bunch repetition rates (500 MHz) within long trains (140 s) and with suciently long cathode lifetimes. In particular the laser pulse energy in UV, for such long pulse trains, is currently limited due to a degradation of the beam quality during the 4th harmonic frequency conversion process. Using the 2nd harmonic (green laser beam), provided it is matched with a low photoemission threshold photocathode material, would overcome this limitation. Cesium antimonide (Cs3Sb), being a photoemissive material in the visible range,...

  20. 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)

  1. Mid-Infrared Laser Beam Diagnostic Wavefront Analyzer

    Science.gov (United States)

    Goranson, Rex; Blea, Joe; Chipps, Art; Denton, Grant; Houchard, Jeff

    1988-08-01

    The Rockwell Wavefront Analyzer (RWA) is an integrated beam diagnostic tool developed for the US Army, STEWS, WSMR, for the MIRACL device. It accepts a 2.5 cm square nominally collimated DF laser beam input of approximately 5 W power level. The electrical signals are reduced and analyzed by an on-line computer processor. The ultimate outputs are plots including total beam power and angular jitter in the x and y axes, an irradiance map of the beam on a 32 X 32 square grid, and a wavefront map of the beam on the same grid. Wavefront aberration poly-nomial coefficient listings are also generated. The wavefront is obtained from measurements of its local slope in two axes by means of a classical Hartmann test done by scanning the pupil with holes in a rotating drum. Earlier versions of this instrument we called SHAPE, for Scanning Hartmann Analyzer Plate Experiment. This design would be SHAPE IV. A single indium antimonide photopot detector measures the transverse ray aberrations, which are then subjected to elaborate processing to extract the polynomial wavefront coefficients. Another photopot is the jitter sensor. Each photopot measures power to normalize the X and Y signals; these "Z" signals also provide the beam power and local irradiance signals.

  2. 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

  3. 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

  4. Free electron laser induced two-photon photoconductivity in Hg1-xCdxTe

    Institute of Scientific and Technical Information of China (English)

    YUAN; Xianzhang

    2001-01-01

    [1]Nathan, V., Guenther, A. H., Mitra, S. S., Review of multiphoton absortion in crystalline solids, J. Opt. Soc. Am. B, 1985, 2: 294—316.[2]Gibson, A. F., Hatch, C. B., Maggs, P. N. D. et al., Two-photon absorption in indium antimonide and germanium, J. Phys., C, 1976, 9: 3259—3275.[3]Miller, A., Johnston, A., Dempsey, J. et al., Two-photon absorption in InSb and Hg1-xCdxTe, J. Phys. C, 1929, 12: 4839—4849.[4]Burghoorn, J., Anderegg, V. F., Klaassen, T. O. et al., Free electron laser induced two-photon absorption in Hg1-xCdxTe, Appl. Phys. Lett., 1992, 61(19): 2320—2322.[5]Hui, Z. X., Yang, Z. H., Free Electron Laser (in Chinese), Beijing: National Defense Industry Press, 1995, 7—8.[6]Matter, J. C., Smirt, A. L., Scully, M. O., Saturable transmission in mercury cadmium telluride, Appl. Phys. Lett., 1976, 28(9): 507—509.[7]Nurmikko, A. V., Nonlinear absorption at 10.6 μm in Hg1-xCdxTe, Optics Communications, 1976, 18(4): 522—524.[8]Catalano, I. M., Cingolani, A., Minafra, A., Multiphoton transitions in ionic crystals, Phys. Rev. B, 1972, 5(4): 1629—1632.[9]Blakemore, J. S., Semiconductor Statistics, Oxford: Pergamon, 1962, 221—222.[10]Shen, S. C., Optical Property of Semiconductor (in Chinese), Beijing: Science Press, 1992, 392—394.

  5. Detached phenomenon: Its effect on the crystal quality of Ga{sub (1−x)}In{sub x}Sb bulk crystal grown by the VDS technique

    Energy Technology Data Exchange (ETDEWEB)

    Gadkari, Dattatray, E-mail: db.gadkari@gmail.com [Department of Physics, Mithibai College, Mumbai 400056 (India)

    2013-05-15

    Vertical directional solidification (VDS) technique is used on the combined growth principals of the conventional methods since 1994, which leads to the detached growth. For evaluation of the detached growth, five bulk ingots of indium doped gallium–antimonide GaSb:In (In = 0.5, 0.25, 0.15) have been grown – without the seed, without contact to the ampoule wall, without coating and without external pressure. The gap is attributed to compensate the differential thermal dilatation that is grown with the reduced diameter than the diameter of the ampoule. VDS experiments have been proved that the sum of the contact angle and growth angle is large enough to allow detachment without any additional pressure difference under the melt to offset hydrostatic pressure. A meniscus forms at the bottom of the melt, the capillarity effect establishes due to which spontaneous gap could be created by the melt free surface, thus no thermal shear stress and thermo-mechanical stresses at the interface. Detached grown bulk GaSb:In crystals showed superior crystal quality with the highest physical properties and mobility than the crystals grown ever. The axial and radial composition profile of the grown GaSb:In ingots showed variation ≤10%. From the conical region, dislocation density decreases in the growth direction and reaches less than 10{sup 3} cm{sup −2}. - Highlights: ► Detachment: without seed, without ampoule contact, without coating, without external pressure. ► Detached ingot growth samples showed the highest physical properties and the carrier mobility. ► Initial to final transition: in detached growth, dislocations decreases and less than 10{sup 3} cm{sup −2}. ► Detached samples: Raman spectrum shows only TO phonon (110) direction of single orientation. ► Detached ingot: FTIR shows highest transmissions % but decreases on increase doping in samples.

  6. 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

  7. Advanced photovoltaic power systems using tandem GaAs/GaSb concentrator modules

    Science.gov (United States)

    Fraas, L. M.; Kuryla, M. S.; Pietila, D. A.; Sundaram, V. S.; Gruenbaum, P. E.; Avery, J. E.; Dihn, V.; Ballantyne, R.; Samuel, C.

    1992-01-01

    In 1989, Boeing announced the fabrication of a tandem gallium concentrator solar cell with an energy conversion efficiency of 30 percent. This research breakthrough has now led to panels which are significantly smaller, lighter, more radiation resistant, and potentially less expensive than the traditional silicon flat plate electric power supply. The new Boeing tandem concentrator (BTC) module uses an array of lightweight silicone Fresnel lenses mounted on the front side of a light weight aluminum honeycomb structure to focus sunlight onto small area solar cells mounted on a thin back plane. This module design is shown schematically. The tandem solar cell in this new module consists of a gallium arsenide light sensitive cell with a 24 percent energy conversion efficiency stacked on top of a gallium antimonide infrared sensitive cell with a conversion efficiency of 6 percent. This gives a total efficiency 30 percent for the cell-stack. The lens optical efficiency is typically 85 percent. Discounting for efficiency losses associated with lens packing, cell wiring, and cell operating temperature still allows for a module efficiency of 22 percent which leads to a module power density of 300 Watts/sq. m. This performance provides more than twice the power density available from a single crystal silicon flat plate module and at least four times the power density available from amorphous silicon modules. The fact that the lenses are only 0.010 ft. thick and the aluminum foil back plane is only 0.003 ft. thick leads to a very lightweight module. Although the cells are an easy to handle thickness of 0.020 ft., the fact that they are small, occupying one-twenty-fifth of the module area, means that they add little to the module weight. After summing all the module weights and given the high module power, we find that we are able to fabricate BTC modules with specific power of 100 watts/kg.

  8. 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

  9. Enhancing selectivity of infrared emitters through quality-factor matching

    Science.gov (United States)

    Sakr, Enas; Zhou, Zhiguang; Bermel, Peter

    2015-09-01

    It has recently been proposed that designing selective emitters with photonic crystals (PhCs) or plasmonic metamaterials can suppress low-energy photon emission, while enhancing higher-energy photon emission. Here, we will consider multiple approaches to designing and fabricating nanophotonic structures concentrating infrared thermal radiation at energies above a critical threshold. These are based on quality factor matching, in which one creates resonant cavities that couple light out at the same rate that the underlying materials emit it. When this quality-factor matching is done properly, emissivities can approach those of a blackbody, but only within a selected range of thermal photon energies. One potential application is for improving the conversion of heat to electricity via a thermophotovoltaic (TPV) system, by using thermal radiation to illuminate a photovoltaic (PV) diode. In this study, realistic simulations of system efficiencies are performed using finite-difference time domain (FDTD) and rigorous coupled wave analysis (RCWA) to capture both thermal radiation and PV diode absorption. We first consider a previously studied 2D molybdenum photonic crystal with a commercially-available silicon PV diode, which can yield TPV efficiencies up to 26.2%. Second, a 1D-periodic samarium-doped glass emitter with a gallium antimonide (GaSb) PV diode is presented, which can yield efficiencies up to 38.5%. Finally, a 2D tungsten photonic crystal with a 1D integrated, chirped filter and the GaSb PV diode can yield efficiencies up to 38.2%; however, the fabrication procedure is expected to be more challenging. The advantages and disadvantages of each strategy will be discussed.

  10. Special Issue featuring invited articles arising from UK Semiconductors 2012

    Science.gov (United States)

    Clarke, Edmund; Wada, Osamu

    2013-07-01

    Semiconductor research has formed the basis of many technological advances over the past 50 years, and the field is still highly active, as new material systems and device concepts are developed to address new applications or operating conditions. In addition to the development of traditional semiconductor devices, the wealth of experience with these materials also allows their use as an ideal environment for testing new physics, leading to new classes of devices exploiting quantum mechanical effects that can also benefit from the advantages of existing semiconductor technology in scalability, compactness and ease of mass production. This special issue features papers arising from the UK Semiconductors 2012 Conference, held at the University of Sheffield. The annual conference covers all aspects of semiconductor research, from crystal growth, through investigations of the physics of semiconductor structures to realization of semiconductor devices and their application in emerging technologies. The 2012 conference featured over 150 presentations, including plenary sessions on interband cascade lasers for the 3-6 µm spectral band, efficient single photon sources based on InAs quantum dots embedded in GaAs photonic nanowires, nitride-based quantum dot visible lasers and single photon sources, and engineering of organic light-emitting diodes. The seven papers collected here highlight current research advances, taken from across the scope of the conference. The papers feature growth of novel nitride-antimonide material systems for mid-infrared sources and detectors, use of semiconductor nanostructures for charge-based memory and visible lasers, optimization of device structures either to reduce losses in solar cells or achieve low noise amplification in transistors, design considerations for surface-emitting lasers incorporating photonic crystals and an assessment of laser power convertors for power transfer. The editors of this special issue and the conference

  11. 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.

  12. High-performance IR detectors at SCD present and future

    Science.gov (United States)

    Nesher, O.; Klipstein, P. C.

    2006-03-01

    For over 27 years, SCD has been manufacturing and developing a wide range of high performance infrared detectors, designed to operate in either the mid-wave (MWIR) or the long-wave (LWIR) atmospheric windows. These detectors have been integrated successfully into many different types of system including missile seekers, time delay integration scanning systems, hand-held cameras, missile warning systems and many others. SCD's technology for the MWIR wavelength range is based on its well established 2D arrays of InSb photodiodes. The arrays are flip-chip bonded to SCD's analogue or digital signal processors, all of which have been designed in-house. The 2D focal plane array (FPA) detectors have a format of 320×256 elements for a 30-μm pitch and 480×384 or 640×512 elements for a 20-μm pitch. Typical operating temperatures are around 77-85 K. Five years ago SCD began to develop a new generation of MWIR detectors based on the epitaxial growth of antimonide based compound semiconductors (ABCS). This ABCS technology allows band-gap engineering of the detection material which enables higher operating temperatures and multi-spectral detection. This year SCD presented its first prototype FPA from this program, an InAlSb based detector operating at a temperature of 100 K. By the end of this year SCD will introduce the first prototype MWIR detector with a 640×512 element format and a pitch of 15 μm. For the LWIR wavelength range SCD manufactures both linear Hg1-xCdxTe (MCT) detectors with a line of 250 elements and time delay and integration (TDI) detectors with formats of 288×4 and 480×6. Recently, SCD has demonstrated its first prototype uncooled detector which is based on VOx technology and which has a format of 384×288 elements, a pitch of 25 μm, and a typical NETD of 50 mK at F/1. In this paper, we describe the present technologies and products of SCD and the future evolution of our detectors for the MWIR and LWIR detection.

  13. 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

  14. Advanced IR detector design at SCD: from D3C to ABCS

    Science.gov (United States)

    Nesher, Ofer; Klipstein, Philip C.; Weiss, Eliezer

    2004-07-01

    Over the past 27 years, SCD has developed and manufactured more than 30 types of Infrared Detector, both with support from the Israeli MOD and in cooperation with institutions and companies such as the Technion, Soreq NRC, RICOR and RAFAEL. SCD's current production line includes Hg1-xCdxTe (MCT) devices with up to 480x6 elements operating in Time Delay and Integration (TDI) mode and InSb Focal Plane Arrays (FPAs) with up to 640x512 elements, all available in various configurations including fully integrated Detector-Dewar-Cooler (DDC) packages. Such DDCs have been designed to range from the very small to the very large. At one end the Piccolo DDC is a small, low weight and power detector, ideal for compact low cost imagers such as handheld IR cameras. At the other end, we manufacture a very long (2048x16) bi-directional TDI InSb detector designed for "whiskbroom scanning" systems. This device consists of four modules precisely butted on a single substrate, with each 512x16 module connected to a single signal processor. In 2003, SCD announced its new breakthrough Digital Read Out Integrated Circuit (ROIC) technology: Digital DDC or D3C. This readout system, with excellent performance and increased flexibility is the first in a series of new imaging solutions that SCD is developing to meet future demands of noise and power reduction, combined with greater wavelength selectivity. To continue along this path we have also been developing our new ABCS (Antimonide Based Compound Semiconductor) technology, which we first reported in 2002. The ABCS program, combining SCD's existing strengths in InSb FPA systems with new concepts in bandgap engineering and smart structure design, is aimed at multispectral IR detectors operating at higher temperatures. This review discusses some of the key trends at SCD as described above. After surveying the performance of SCD's current InSb technology, SCD's evolution towards the next generations will be described, including the

  15. On the crystal structure and physical properties of the UFeSb{sub 2} compound

    Energy Technology Data Exchange (ETDEWEB)

    Gonçalves, A.P., E-mail: apg@ctn.ist.utl.pt [C2TN, Instituto Superior Técnico, Universidade de Lisboa, CFMC-UL, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Henriques, M.S.; Waerenborgh, J.C. [C2TN, Instituto Superior Técnico, Universidade de Lisboa, CFMC-UL, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Curlik, I.; Il’kovič, S.; Reiffers, M. [Faculty of Humanities and Natural Sciences, Prešov University, 081 16 Prešov (Slovakia)

    2014-12-15

    Highlights: • Polycrystalline UFeSb{sub 2} was prepared by conventional arc-melting route. • An accurate crystal structure characterization of UFeSb{sub 2} was made. • UFeSb{sub 2} has a ferromagnetic-type transition at 31(1) K. • The ferromagnetic-like properties of UFeSb{sub 2} are determined by the U-sublattice. • Specific heat shows that UFeSb{sub 2} is a medium correlated electron system. - Abstract: The UFeSb{sub 2} 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. UFeSb{sub 2} crystallizes in the tetragonal HfCuSi{sub 2}-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 UFeSb{sub 2} 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 K{sup 2}, which classifies this compound as a medium correlated system.

  16. 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.

  17. Developing high-performance III-V superlattice IRFPAs for defense: challenges and solutions

    Science.gov (United States)

    Zheng, Lucy; Tidrow, Meimei; Aitcheson, Leslie; O'Connor, Jerry; Brown, Steven

    2010-04-01

    The antimonide superlattice infrared detector technology program was established to explore new infrared detector materials and technology. The ultimate goal is to enhance the infrared sensor system capability and meet challenging requirements for many applications. Certain applications require large-format focal plane arrays (FPAs) for a wide field of view. These FPAs must be able to detect infrared signatures at long wavelengths, at low infrared background radiation, and with minimal spatial cross talk. Other applications require medium-format pixel, co-registered, dual-band capability with minimal spectral cross talk. Under the technology program, three leading research groups have focused on device architecture design, high-quality material growth and characterization, detector and detector array processing, hybridization, testing, and modeling. Tremendous progress has been made in the past few years. This is reflected in orders-of-magnitude reduction in detector dark-current density and substantial increase in quantum efficiency, as well as the demonstration of good-quality long-wavelength infrared FPAs. Many technical challenges must be overcome to realize the theoretical promise of superlattice infrared materials. These include further reduction in dark current density, growth of optically thick materials for high quantum efficiency, and elimination of FPA processing-related performance degradation. In addition, challenges in long-term research and development cost, superlattice material availability, FPA chip assembly availability, and industry sustainability are also to be met. A new program was established in 2009 with a scope that is different from the existing technology program. Called Fabrication of Superlattice Infrared FPA (FastFPA), this 4-year program sets its goal to establish U.S. industry capability of producing high-quality superlattice wafers and fabricating advanced FPAs. It uses horizontal integration strategy by leveraging existing III

  18. 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

  19. 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.

  20. 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.)

  1. 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

  2. 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

  3. 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

  4. 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.

  5. Thermoelectric study of INSB secondary phase based nano composite materials

    Science.gov (United States)

    Zhu, Song

    In the past several decades there has been an intensive study in the field of thermoelectric study that is basically materials driven. As the simplest technology applicable in direct heat-electricity energy conversion, thermoelectricity utilizes the Seebeck effect to generate electricity from heat or conversely achieve the solid-state cooling via the Peltier effect. With many technical merits, thermoelectric devices can be used as spot-size generators or distributed refrigerators, however, their applications are restricted by the energy conversion efficiency, which is mainly determined by the figure of merit ZT of the thermoelectric materials that these devices are made of. A higher ZT (ZT=alpha2*sigma/kappa) entails a larger Seebeck coefficient (alpha), a higher electrical conductivity (sigma) and a lower thermal conductivity (kappa). However, it is challenging to simultaneously optimize these three material parameters because they are adversely correlated. To this end, a promising approach to answer this challenge is nano-compositing or microstructuring at multiple length scales. The numerous grain boundaries in nano-composite allow for significant reduction of lattice thermal conductivity via strong phonon scattering and as well an enhanced Seebeck coefficient via, carrier energy filtering effect. As the same grain boundaries also scatter carriers, a coherent interface between grains is needed to minimize the degradation of carrier mobilities. To this end,in-situ, instead of ex-situ, formation of nano-composite is preferred. It is noteworthy that electrical conductivity can be further enhanced by the injection of high-mobility carriers introduced by the secondary nano-phase. In view of the prevalent use of Antimony (Sb) in thermoelectric materials, Indium Antimonide (InSb) naturally becomes one of the most promising nano-inclusions since it possesses one of the largest carrier mobilities (˜7.8 m 2/V-s) in any semiconductors, while at the same time possesses a

  6. 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).