Showing papers on "Antimonide published in 2000"

Electronic structure of Na3Sb and Na2KSb

Abstract: The photoemissive materials ${\mathrm{Na}}_{3}\mathrm{Sb}$ and ${\mathrm{Na}}_{2}\mathrm{KSb}$ are widely applied as photocathodes in light detection devices. Their application is purely electronic, therefore results from band-structure calculations are important to understand the photon-electron conversion in the cathodes of these devices. This study reports results from band-structure calculations for ${\mathrm{Na}}_{3}\mathrm{Sb}$ and ${\mathrm{Na}}_{2}\mathrm{KSb}.$ These calculations show that the monoalkali antimonide has a small band gap with respect to the photon absorption onset. For the bialkali antimonide the discrepancy between the band gap and the photon absorption onset is significantly smaller. Therefore the photoelectrons in the monoalkali antimonide have a higher escape barrier than those in the bialkali antimonide. This is likely the reason for the higher emission rates of the bialkali antimonide ${\mathrm{Na}}_{2}\mathrm{KSb}.$

Active material of thermoelectricity and thermal converter comprising it

Abstract: PROBLEM TO BE SOLVED: To provide a thermoelectric material having a high Z value as well as being excellent in temperature stability. SOLUTION: Related to a thermal converter comprising a p-doped or an n-doped semiconductor material, the semiconductor material is at least one kind of ternary material formed by combining at least two kinds of compounds among material substance classes, while selected among them; silicide, boride, germanide, telluride, sulfide, selenide, antimonide, lead compound, and semiconductor oxide.

Compound semiconductor multilayer thin film and semiconductor device

Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor device which is very reliable and has a high mobility and a high resistance over a wide range of temperature by forming a strained aluminum.gallium.indium antimonide carrier supply layer which is doped with impurities and whose lattice constant in the direction horizontal with the surface of a substrate is the same as that of InSb. SOLUTION: On a substrate 01 made of semi-insulating or insulating material whose electrical conductivity per unit area is 0.005 S (siemens) or below, a doped InSb buffer layer 02 and an undoped InSb active layer 03 are formed. Then, a strained aluminum.gallium.indium antimonide(AlGaInSb) carrier supply layer 04 which is doped with impurities and whose lattice constant in the direction horizontal with the surface of the substrate 01 is the same as that of InSb is formed. Thereon, an undoped InSb supply layer is formed.

Thermoelectric Properties of Some Phosphide Skutterudite Materials

Abstract: The synthesis and thermoelectric properties of CoP3, CeFe4P12 and CeRu4P12 have been investigated. These compounds were made by recrystallization from Sn flux. The samples were analyzed by x-ray diffraction and electron microprobe analysis for phase purity. Electrical resistivity and Seebeck coefficient measurements showed that all three compounds are p-type semiconductors, in agreement with theoretical predictions and previous literature results. The large difference between the thermal conductivity of the binary and filled compounds can be primarily attributed to the additional phonon scattering by Ce atoms rattling inside the empty cages. The properties of the phosphide compounds are compared to their antimonide analogs and discussed in order to obtain further insights into the transport properties of skutterudite materials. Guidelines for optimizing thermoelectric properties of this class of compounds are also provided.

Semiconductor chip used in optical communications comprises a semiconductor laser element, and a beam former integrated in the chip for forming a laser beam emitted from the element

Abstract: Semiconductor chip (100) comprises a semiconductor laser element (102); and a beam former (103) integrated in the chip for forming a laser beam emitted from the element. The beam former is arranged in the outlet direction of the laser beam so that the beam is guided through the former. An Independent claim is also included for a process for the production of a semiconductor chip. Preferred Features: The beam former is monolithically integrated in the semiconductor chip and is made of an aluminum-containing material, preferably a material system made of indium-gallium-aluminum antimonide, gallium-aluminum-arsenide antimonide or indium-aluminum-arsenic antimonide.

Antimonide interband and intersubband mid-IR and terahertz lasers

Abstract: Antimonide semiconductor lasers for the mid-infrared and terahertz spectral regions are considered. It is predicted that optically pumped interband type-II lasers will be advantageous at long wavelengths, out to λ≈100 μm . In the mid-IR, antimonide intersubband lasers should have higher gains and longer carrier lifetimes than InGaAs/InAlAs quantum cascade lasers, and hence have prospects for room-temperature cw operation. Spin-polarized antimonide intersubband lasers with applied magnetic fields are projected to display room-temperature cw emission at λ=16 μm .

Growth of controlled- thermopower- anisotropy cadmium antimonide crystals

Abstract: Experimental data are presented which demonstrate that the thermopower anisotropy of CdSb crystals can be increased almost threefold, to obtain a difference in the room-temperature thermopower tensor components of up to 750 µV/K, by annealing the seed or passing an electric current through it and by optimizing zone-melting conditions. This procedure is used to grow CdSb crystals for thermoelectric converters employed in commercial illumination radiometers.

Performance Limits of Low Bandgap Thermophotovoltaic Antimonide-Based Cells for Low Temperature Radiators

Abstract: This paper assesses the performance of antimonide-based thermophotovoltaic cells fabricated by different technologies. In particular, the paper compares the performance of lattice matched quaternary (GaInAsSb) cells epitaxially grown on GaSb substrates to the performance of ternary (GaInSb) and binary (GaSb) cells fabricated by Zn diffusion on bulk substrates. The focus of the paper is to delineate the key performance advantages of the highest performance-to-date of the quaternary cells to the performance of the alternative ternary and binary antimonide-based diffusion technology. The performance characteristics of the cells considered are obtained from PC-1D simulations using appropriate material parameters.

Preparation and Evaluation of Phosphide Skutterudites

Abstract: : This report summarizes a three and a half year program on the synthesis of phosphide skutterudite compounds using direct reaction and flux methods as well as a newly developed technique, the molten salt electrodeposition. A number of successfully prepared materials were measured for their thermoelectric properties as a function of temperature. It was found that some of these phosphide compounds exhibited semiconducting behavior in contrast to their antimonide analogs. This provided an opportunity to investigate skutterudite compounds having electrical properties ranging from semiconductors to semimetals/metals when phosphorus was replaced by antimony. In addition, the effect of anion size and mass on thermal conductivity of these compounds were experimentally verified. By extending our study to a binary cobalt phosphide-arsenide solid solution, we found that the thermoelectric properties were improved. We expected that this result could be applied to other filled ternary compounds, including the state-of-the-art CeFe4Sb12.

A Novel Single Step Lapping and Chemo-Mechanical Polishing Scheme for Antimonide Based Semiconductors Using 1 µm Agglomerate-Free Alumina Slurry

Abstract: A novel approach for a single step lapping and chemical-mechanical polishing of antimonide-based III-V compounds using agglomerate-free alumina slurries is presented. Relatively high removal rates, minimal scratching, and low surface roughness have been obtained. The effects of slurry preparation cycle on the slurry properties and chemomechanical polishing results are discussed.