Showing papers on "Antimonide published in 2005"

Antimonide-based compound semiconductors for electronic devices: A review

Abstract: Several research groups have been actively pursuing antimonide-based electronic devices in recent years. The advantage of narrow-bandgap Sb-based devices over conventional GaAs- or InP-based devices is the attainment of high-frequency operation with much lower power consumption. This paper will review the progress on three antimonide-based electronic devices: high electron mobility transistors (HEMTs), resonant tunneling diodes (RTDs), and heterojunction bipolar transistors (HBTs). Progress on the HEMT includes the demonstration of Ka- and W-band low-noise amplifier circuits that operate at less than one-third the power of similar InP-based circuits. The RTDs exhibit excellent figures of merit but, like their InP- and GaAs-based counterparts, are waiting for a viable commercial application. Several approaches are being investigated for HBTs, with circuits reported using InAs and InGaAs bases.

A W-band InAs/AlSb low-noise/low-power amplifier

Abstract: The first W-band antimonide based compound semiconductor low-noise amplifier has been demonstrated. The compact 1.4-mm/sup 2/ three-stage co-planar waveguide amplifier with 0.1-/spl mu/m InAs/AlSb high electron mobility transistor devices is fabricated on a 100-/spl mu/m GaAs substrate. Minimum noise-figure of 5.4dB with an associated gain of 11.1 dB is demonstrated at a total chip dissipation of 1.8 mW at 94 GHz. Biased for higher gain, 16/spl plusmn/1 dB is measured over a 77-103 GHz frequency band.

Structure and Physical Properties of Ternary Antimonide YbCrSb3

Abstract: The ternary rare-earth antimonide YbCrSb3 was prepared by arc-melting of the elements. Its structure was determined by single-crystal X-ray diffraction (Pearson symbol oP20, orthorhombic, space group Pbcm, Z = 4, a = 12.981(3) A, b = 6.140(1) A, c = 5.993(1) A). YbCrSb3 is isostructural to LaCrSb3 and CeCrSb3, and extends the RECrSb3 series (previously known for RE = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy) to the latest rare-earth member yet and to one that is essentially divalent instead of trivalent. Electrical resistivity measurements on single crystals and magnetic susceptibility measurements on powders revealed a magnetic ordering transition at TC = ∼280 K, the highest observed so far in the RECrSb3 series. The isothermal magnetization at 100 K indicated an approach to saturation, but with low values (0.08 μB/mol at 9 T). These results suggest a ferromagnetic or canted antiferromagnetic structure.

Sb-based HEMTs with InAlSb/InAs heterojunction

Abstract: Antimonide-based HEMTs with a 0.35 µm gate length have been fabricated with an InAlSb/InAs heterojunction. The new Te-doped MBE material, which does not contain highly-reactive AlSb, exhibits a Hall mobility of 23,500 cm2/V-s and a sheet density of 1.7×1012 cm−2. The devices have a DC transconductance of 1000 mS/mm and an fTLg product of 32 GHz-µm at VDS=0.35 V.

Comparison of thermal characteristics of antimonide and phosphide MQW lasers

Abstract: The thermal characteristics of antimonide ridge waveguide MQW lasers have been investigated numerically and experimentally, and compared with phosphide lasers in detail Using the finite-element method, the heat accumulation and dissipation process of the lasers under CW and pulse driving conditions have been simulated, and quantitative thermal time constants were introduced to describe the cooling efficiency of the lasers The non-uniform temperature distribution inside the active core of the laser and its effects on lasing spectra have been discussed, and confirmed by the measurement of the broadening of the lasing spectrum towards the blue side A way to improve the thermal property of antimonide lasers have also been proposed and discussed

Design and characteristics of strained InAs/InAlAs composite-channel heterostructure field-effect transistors

Abstract: We report composite-channel heterostructure field-effect transistors (HFETs) with an InAs channel and an In0.9Al0.1As subchannel. The HFETs are grown on antimonide buffer layers. Two composite-channel structures with different planar Te doping schemes are designed, fabricated, and characterized. High radio-frequency transconductances of above 0.9 S/mm and ∼55GHz current gain cutoff frequencies are achieved in devices with 500 nm gates. Planar Te doping in the buffer layers reduces the high kink-effect currents otherwise found in InAs/AlSb HFETs, an effect which can be attributed to either increased breakdown field in the In0.9Al0.1As subchannel or to suppression of hole blocking in the buffer. The present limitations to device performance and suggested approaches for their elimination are discussed.

Influence of native defects on the infrared transmission of undoped Ga1−xInxSb bulk crystals

Abstract: The below bandgap infrared transmission (up to 25 µm) in undoped Ga1−xInxSb bulk crystals has been studied for the first time and found to be limited by native defects such as antisites and vacancies found in antimonide-based III–V compounds. For the gallium-rich alloy compositions (x 0.5 (the indium-rich alloy compositions), the crystals exhibit n-type conductivity when the net donor concentration and indium content in the crystals increase. A correlation between the optical transmission and the residual carrier concentration arising from the native acceptors and donors has been observed. Due to donor-acceptor compensation, crystals with alloy compositions in the range of x=0.5−0.7 exhibit high optical transmission for a wide wavelength range (up to 22 µm). The light hole to heavy hole interband transition in the valence band and the free electron absorption in the conduction band have been found to be the two dominant absorption processes.

Atomistic simulation studies of iron sulphide, platinum antimonide and platinum arsenide

Abstract: We present the results of atomistic simulations using derived inter- atomic potentials for the pyrite-structured metal chalcogenides FeS2 ,P tSb 2 and PtAs2. Structural and elastic constants were calculated and compared with experimental measurements. Surface energies of low-index surfaces were calculated and closely reflected the measured stabilities of these compounds. Equivalent surfaces on the pyrite and marcasite structures of FeS2 explained the experimentally observed intergrowths of the two phases.

The wide and the narrow: DARPA/MTO programs for RF applications in wide bandgap and antimonide-based semiconductors

Abstract: This paper discusses two DARPA/MTO III-V semiconductor material development programs, the wide bandgap semiconductor for RF applications (WBGS-RF) program and the antimonide-based compound semiconductor (ABCS) program. For WBGS-RF, results are detailed from the recently-completed phase I effort with a focus on semi-insulating substrates and epitaxial growth. Also detailed are the goals and early progress report from phase II of WBGS-RF. Near the end, summarized are results achieved in the recently-completed ABCS program.

Electrode material of cobalt base antimonide pyroelectric material and preparing process thereof

Abstract: The material of the electrode applies the molybdenum with the thickness of 0.5-1.5 mm. The electrode of cobalt antimonide base thermoelectric material achieves the combination, by introducing the titanium through the two-step procedure, the discharging and the sinter. The sinter of the cobalt antimonide thermoelectric material and the combination between the powder and the electrode material are processed simultaneously. The high intensity of combination, excellent stability and convenient combination technology are supplied.

BCl3/Ar ICP Etching of GaSb and Related Materials for Quaternary Antimonide Laser Diodes

Abstract: Inductively coupled plasma (ICP) etching of GaSb, AlGaAsSb, and InGaAsSb using BCl 3 /Ar plasma discharges was investigated for the fabrication of GaInAsSb/AlGaAsSb/GaSb laser diodes. Etching rates and selectivity were characterized as functions of gas flow ratio, accelerating voltage, and ICP source power, and the etching mechanism was discussed in detail. It is observed that the etch rate of GaSb and AlGaAsSb is much higher than that of InGaAsSb. The etched surfaces of GaSb, AlGaAsSb all have comparable root-mean-square roughness to the unetched samples over a wide range of plasma conditions; however, it is much rougher in etching of InGaAsSb. The selectivity between GaSb and AlGaAsSb was close to unity over the entire range of plasma conditions investigated, which is desirable for the fabrication of quaternary antimonide laser diodes.

Method for making transition metal tri-antimonide with skutterudite structure

Abstract: The invention discloses a process for preparing skutterudite structure transition metal antimonide through water heating / solvent thermal method which consists of, Co, Ni, Ru, Rh, Os, Ir} and Sb or As into deionized water or organic solvent based on the proportion determined by the chemical composition of the destination product, and charging reducing agent, sealing in high-pressure reaction kettle, reacting 10-100 hours at 100-300 deg. C, cooling down and washing repeatedly, and drying.

Surface inactivating method for antimonite and its device

Abstract: This invention relates to a surface sulfur passivation method for a new antimonide and its devices including surface preprocess before the passivation and the method which overcomes the rough surface formed by conventional surface erosion and gets a dense flat smooth surface and interface shape to guarantee successive rate and control of technology and effectively increases the response degree and detection rate of detectors. The invented antimonide neutral ammonium sulfide passivation technology has better passivation result than the traditional basic one.

Dry etching, surface passivation and capping processes for antimonide based photodetectors

Abstract: III-V antimonide based devices suffer from leakage currents. Surface passivation and subsequent capping of the surfaces are absolutely essential for any practical applicability of antimonide based devices. The quest for a suitable surface passivation technology is still on. In this paper, we will present some of the promising recent developments in this area based on dry etching of GaSb based homojunction photodiodes structures followed by various passivation and capping schemes. We have developed a damage-free, universal dry etching recipe based on unique ratios of Cl2/BCl3/CH4/Ar/H2 in ECR plasma. This novel dry plasma process etches all III-V compounds at different rates with minimal damage to the side walls. In GaSb based photodiodes, an order of magnitude lower leakage current, improved ideality factor and higher responsivity has been demonstrated using this recipe compared to widely used Cl2/Ar and wet chemical etch recipes. The dynamic zero bias resistance-area product of the Cl2/BCl3/CH4/Ar/H2 etched diodes (830 Ω cm2) is higher than the Cl2/Ar (300 Ω cm2) and wet etched (330 Ω cm2) diodes. Ammonium sulfide has been known to passivate surfaces of III-V compounds. In GaSb photodiodes, the leakage current density reduces by a factor of 3 upon sulfur passivation using ammonium sulfide. However, device performance degrades over a period of time in the absence of any capping or protective layer. Silicon Nitride has been used as a cap layer by various researchers. We have found that by using silicon nitride caps, the devices exhibit higher leakage than unpassivated devices probably due to plasma damage during SiNx deposition. We have experimented with various polymers for capping material. It has been observed that ammonium sulfide passivation when combined with parylene capping layer (150 Å), devices retain their improved performance for over 4 months.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Cobalt antimonide based thermoelectric composite material and its preparation

Abstract: The invention was involved in cobalt antimonides based thermoelectric complex material and its preparation method. The complex material was based on CoSb3 or BayCoSb12,and 0 is less than or equal to y is less than or equal to 0.44.The nanometer particle with lower than 100nm was added at the temperature of high temperature solid phase reaction, the addition was 0-8wt%of the base. The nanometer particle was distributed equably into the base by original position diffusion. All the above nanometer particle was one kind of BN, C60, Si3N4 or Ba6C60. The first step was to produce complex powder and the second step was to sintering rapidly. Compared with the base, the index of heat-electricity transition performance of CoSb3 complex material was increased 30-50%. ZT value of BayCoSb12 was 1.2 under 850K. The efficiency of heat-electricity transition performance was 15% and there was a good practice foreground.

The First Titanium Molybdenum Antimonide: Ti5.42Mo2.58Sb9, a Substitution Variant of Zr2V6Sb9

Abstract: The new ternary antimonide Ti5.42(2)Mo2.58Sb9 was uncovered by a reaction of the elements under exclusion of air at 1150 °C. It crystallizes in a ternary substitution variant of the V7.5Sb9 type, a structure not known to exist in either the Ti/Sb or the Mo/Sb system. The crystal structure of Ti5.42Mo2.58Sb9 was determined from single crystal X-ray data: space group P4/nmm, with a = 9.8178(8) A, c = 7.1857(8) A, V = 692.6(1) A3, Z = 2, R1 = 0.025, wR2 = 0.052 (all data). The structure contains four metal atom sites, two thereof occupied solely by Ti atoms, and two by different Ti/Mo mixtures. The former two correspond to the Zr sites, and the latter two to the V sites of the isostructural antimonide Zr2V6Sb9. The crystal structure is comprised of chains of face-sharing TiSb8 square antiprisms, Ti/Mo tetrahedra and Sb atom pairs and squares. The electronic structure, computed with the LMTO approximation, is indicative of metallic properties. In addition to the dominating metal–Sb bonds, strong metal–metal and Sb–Sb bonds exist as well in Ti5.42Mo2.58Sb9. The Mo content per metal site increases with increasing metal–metal interactions.

Antimonides having novel combinations of properties

Abstract: The invention relates to thermoelectric generators or Peltier systems comprising an antimonide as a semiconductor material. According to said method, a substituted antimonide is used, in which the crystal lattice of the metal antimonides is partially substituted with sulfides, selenides and/or tellurides of the metals antimony, silicon, germanium, zinc, lead, arsenic and/or bismuth.

Quantum cascade laser

Abstract: A quantum cascade laser has an emission wavelength below 3.4 mu m and above 1.5 mu m. The semiconductor multi-layer structure has a cup layer of indium gallium arsenide (InGaAs) and a barrier layer of aluminum arsenic antimonide (AlAsSb). The cup layer thickness is in the optically active range of 1 to 4 nm.

A novel surface preparation methodology for epi-ready antimonide based III-V substrates

Abstract: Surfaces of GaSb substrates currently available from various commercial vendors are nowhere close to device grade GaAs, Si or InP wafer surfaces. Hence epitaxial growth and device fabrication on as-received commercial substrates poses significant difficulties amongst antimonide based researchers. Antimonide based materials are known to have poor surface oxide quality and not so well understood chemical reactions with various chemicals used to remove the oxides prior to growth. There are no existing reports on the detailed recipe for the preparation of "atomically flat and clean" surfaces that works on wafers obtained from various commercial vendors. This paper presents a detailed recipe for obtaining atomically flat and clean GaSb surfaces, irrespective of the initial polishing source. The same recipe (with slight modification) has been found to be successful with other III-V and II-VI compounds. The novel surface preparation process developed in our laboratory includes, chemical-mechanical polishing using an agglomerate-free sub-micron alumina slurry on a soft pad such as velvet, surface cleaning using dilute ammonium or potassium hydroxide-H2O solution and surfactant or glycerol, surface degreasing using organic solvents, oxide desorption using HCl-H2O and HF-H2O mixtures, mild chemical etching using ammonium sulfide and a final rinse in high purity deionized (DI) water and methanol. Using this recipe, we have been able to achieve surfaces with atomic flatness (RMS surface roughness close to 0.5 nm over a 10 x 10 mm2) and extremely clean surfaces, irrespective of the initial contamination or the sources of the wafers. Results of wafer surfaces before and after polishing using our recipe will be presented.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Metalorganic vapor-phase epitaxy of antimonide for application to 1.55 /spl mu/m VCSELs on InP substrates

Abstract: A distributed Bragg reflector at 1.55 mum grown monolithically by metalorganic vapor-phase epitaxy is reported. The DBR composed of 24 AlGaAsSb/InP periods achieves a reflectivity of 99.5% over the 2 inch wafer surface

Method for manufacturing semiconductor substrate

Abstract: PROBLEM TO BE SOLVED: To manufacture a ridge whose width and height is uniform at the same semiconductor substrate or between semiconductor substrates SOLUTION: A polyimide resin film 3 of a heat resistant resin layer is applied to the surface of a gallium arsenide(GaAs) substrate 1, and a stripe-shaped opening 4 is formed at a position corresponding to the formation region of the ridge of the polyimide resin film 3 Then, a GaAs layer 5 being a semiconductor layer as the ridge constituted of the same materials as those of the substrate is grown by a metal organic vapor phase growing method or a molecular beam growing method on the surface of the GaAs substrate 1 exposed from the stripe-shaped opening 4 by using the polyimide resin film 3 as a mask In this case, a growing temperature at the time of manufacturing the ridge is set so as to range from 425°C to 480°C lower than the decomposition temperature of the polyimide resin After growth, the polyimide resin film 3 is removed, and the ridge is formed on the GaAs substrate 1 Also, the substrate is configured of not only GaAs but also at least one type of aluminum arsenide (AlAs), indium phosphide (InP), gallium antimonide (GaP) and antimonide (GaSb) COPYRIGHT: (C)2005,JPO&NCIPI

Nanocrystalline thermoelectric alloys: Processing, chemistry and characterization

Abstract: A novel chemical alloying method has been developed for the fabrication of nanocrystalline thermoelectric alloys cobalt antimonide, CoSb3, and bismuth telluride, Bi2Te3. The method combines a solut ...

Antimonide-based optical devices

Abstract: An optical device includes an antimonide-containing substrate, and an antimonide-containing n-doped layer provided on the substrate. The optical device further includes an antimonide-containing i-doped layer provided on the n-doped layer, an antimonide-containing p-doped layer provided on the i-doped layer, and an antimonide-containing p + -doped layer provided on the p-doped layer.