Semiconductors GaSb Research Articles

Identifying the by-products on the surface of porous GaAs and GaSb semiconductors by Raman scattering

Identifying the by-products on the surface of porous GaAs and GaSb semiconductors by Raman scattering

Solid state phase equilibria in the Fe–Ga–Sb ternary system at 600 °C

Solid state phase equilibria in the ternary Fe–Ga–Sb diagram were determined at 600 °C using experimental techniques such as X-ray diffraction, electron probe microanalysis and scanning electron microscopy. Very limited solid solutions were measured in the binary constituent Fe–Ga and Fe–Sb compounds except for the ε-phase (Fe ≈2.55Sb 2) which extends from 42 to 48 at.% Sb. In the Fe-rich part of the diagram, a ternary phase Fe t Ga 2− x Sb x (2.15≤ t≤2.80) was evidenced which corresponds in fact to a solid solution into which Ga and Sb substitute one another on the same hexagonal sublattice. This phase, which can be truly considered as a pseudo-binary one since its origin results from the ε-phase, shows an extended homogeneity range with a Ga-rich limit corresponding to the formula Fe t Ga 0.8Sb 1.2. Moreover, it crystallizes in hexagonal symmetry with a disordered structure derivative from the NiAs-type ( B8 1). This pseudo-binary phase is in thermodynamic equilibrium with all the binaries of the system except FeGa 3. The main result of the ternary Fe–Ga–Sb diagram remains the existence of a diphasic region between the Fe t Ga 2− x Sb x phase (1.2≤ x≤1.6; 2.15≤ t≤2.80) and the semiconductor GaSb. Nevertheless, at 600 °C, this pseudo-binary phase does not extend up to the Fe 3GaSb composition which is stoichiometric in Ga and Sb. Finally, a comparative study has been made with the three other ternary systems Fe–Ga–As, Ni–Ga–As and Ni–Ga–Sb previously reported, and the consequences for the solid state interdiffusions in Metal/III–V semiconductor heterostructures are discussed.

溶融アンチモンの酸化揮発反応速度

In order to elucidate the kinetics and mechanism of liquid antimony oxidation, experiments were conducted with air and oxygen-argon gas mixtures from the view point of an antimony recovery from antimony-bearing materials such as an used lead-battery and InSb, GaSb semiconductors. The experimental condition was in the temperature range between 973 and 1,173 K, in the oxygen partial pressure range between 0.05 and 0.25 atm.The experimental results show that the oxidation rate increases with increasing gas flow rate, oxygen partial pressure and temperature. An evaporation study of pure water into an argon gas stream was then carried out with respect to the mass transfer characteristics in the gas phase in the reactor used for the present work. The Sherwood number is correlated by the following equation : Sh = 1.38Re0.64Sc1/2. Then the equation was applied to analyze the oxidation kinetics of liquid antimony. The kinetic analysis shows that the mass transfer step in the gas phase controls the overall rate in the experimental range studied, except for the condition of 0.05 atm as the oxygen partial pressure.

Influence of temperature and of structure of antimony substrate on gallium diffusion into the GaSb semiconductor compound

The diffusion coefficient of Ga electrodeposits on Sb electrodeposited thin films, either amorphous or crystalline, was investigated to determine the influence of the morphology and structure of the antimony substrates on the diffusion and reaction process. The Ga/Sb bilayer was studied by SEM–EDS and X-ray diffraction before and after heating at temperatures of 50, 75 and 100°C. The formation of the GaSb semiconductor compound was particularly considered and the activation energy and frequency factor of the process was determined. At these temperatures, Ga was at least partially molten and the diffusion coefficient showed that the geometrical factor was prevailing over the structural one. For example, at 75°C, the values of the diffusion coefficient were 1.5×10 −17 and 6.3×10 −17 m 2 s −1 for the amorphous and crystalline antimony, respectively. On the contrary, at 20°C, a temperature at which Ga is in the solid state, the structural factor prevailed over the geometrical one and values were obtained lower by around three orders of magnitude. The prevailing influence at 20°C was identical to that previously observed for In diffusion into amorphous and crystalline Sb with InSb formation. The experimental results, both at low and high temperatures, are discussed also taking the behaviour of the In–Sb system into account.

Magnetic response of E1 electrons in semiconductor crystals

Abstract The quantized magnetic orbits of electrons at non-zone centre locations of the Brillouin zone are calculated semiclassically at certain symmetry points of the electronic band structure, notably at the L(Λ) and X directions. The effect of ellipsoidal averaging on experiments at the E1 edge of InSb, GaSb and other semiconductors is examined. Comparison is made to fundamental gap experiments at E0. Some anomalies in our experiments are resolved. Comments are made on remnant intrinsic lattice magnetization in InSb and GaSb.

Activationless electron and hole recombination rate in semimetallic semiconductor quantum wells

We present numerical calculations of electron–hole recombination in n-type and p-type semimetallic quantum wells made of InAs and GaSb semiconductors. The overlap between the conduction and valence bands in these wells gives rise to an activationless generation and recombination process that does not require an extra excitation particle such as a phonon or a photon. We calculate this recombination rate using the transfer matrix method with a 8×8 k· p matrix Hamiltonian which takes into account the nonparabolicity and anisotropy of the band structure. Our calculations show that the recombination rates increase with increasing electron and hole energies. We also investigate the effect of an externally applied electrical potential on the recombination rates and consider the case when the transition coefficient, T( E, k ⊥), depends on k ⊥.

Nonlinear optical properties of GaSb and GaInAsSb and their application for phase conjugation in degenerate four-wave mixing

The nonlinear optical properties of, and phase conjugation in, the bulk semiconductor GaSb were investigated at 2.1 µm by use of the Z-scan and the degenerate four-wave mixing techniques. Measurements were also carried out near the fundamental bandgap of the quaternary compound Ga0.87In0.13As0.11Sb0.89. Z-scan measurements as a function of sample temperature, in conjunction with theoretical modeling, identified the predominant sources of the medium nonlinearity to be nonequilibrium free carriers generated through two-photon absorption in GaSb, while it is saturation of real transitions near the fundamental band edge in Ga0.87In0.13As0.11Sb0.89 that was identified as the primary cause of this nonlinearity. Degenerate four-wave mixing phase-conjugate reflectivity of as much as 14% has been achieved in GaSb.

Phase relationships in the ternary Ga–Ni–Sb system

Undesirable chemical reactions between metal contacts and a semiconductor substrate may be prevented by selecting metallization layers which are in thermodynamic equilibrium with the substrate. In order to determine the reaction products resulting from the formation of the Ni–GaSb contact, phase equilibria in the Ga–Ni–Sb system have been established experimentally at 500, 600 and 900°C. For the compound semiconductor GaSb negligible solid solubility of Ni was measured both at 500 and 600°C. In an attempt to clarify the existence of the ternary ϵ-phase in this system, a number of alloys with various compositions were prepared, equilibrated, and examined by XRD, EPMA, and optical microscopy. In addition, the variation of the lattice parameters of the ϵ-phase was determined as a function of composition at 900°C; the results are discussed in terms of the filling of the different lattice positions of the hexagonal unit cell.

Inelastic neutron scattering to very high pressures

Progress in high-pressure and neutron scattering methods has recently allowed measurements of phonon dispersion curves of simple solids at high pressures to 10 GPa. In this technique single crystals of 10–25 mm3 volume are compressed by the Paris-Edinburgh cell and the phonon frequencies are measured on high-flux triple axis spectrometers. Detailed studies of the lattice dynamics of low-compressible systems are feasible, including measurements of mode Gruneisen parameters, elastic constants, and precursor effects of phase transitions. We describe the experimental set-up and illustrate its potential by results on semiconductors (Ge and GaSb) and metals (Fe and Zn) obtained at the LLB (Saclay) and ILL (Grenoble) reactor sources.

Interaction of Ce overlayers with the GaSb(111) surface and oxidation of the Ce/GaSb interface

In this paper we use XPS to study the interaction of Ce overlayers with the semiconductor GaSb(111) surface and Ce-promoted oxidation of the substrate. The results show that when cerium deposits on GaSb(111), it forms weak bonds of Ce–Ga and Ce–Sb with the substrate and makes Ga atoms diffuse out. A Ce–Ga intermetallic phase is formed on the surface. When the exposure of O 2 reaches 50 L, the oxide of cerium, Ce 2O 3, begins to change into unstable CeO 2. The dissociation of CeO 2 results in obvious oxidation of the substrate. The main products are Ga 2O 3, Sb 2O 3 and then Sb 2O 5. After annealing at 250 and 400°C, respectively, some of the oxygen atoms transfer from cerium dioxide toward Ga and Sb in the substrate, by which it strongly promotes the oxidation of the substrate.

Comparison of dry etching of III-V semiconductors in ICl/Ar and IBr/Ar electron cyclotron resonance plasmas

ICl/Ar and IBr/Ar plasmas were found to be promising candidates for room temperature dry etching processing of the III-V semiconductors GaAs, AlGaAs, GaSb, InP, InGaAs, and InSb. Results showed fast etch rates (0.7 µm/min in ICl/Ar and −0.3 µm/min in IBr/Ar), and at high microwave power, 1000 W, good surface morphology (typical root mean square roughness ∼2 nm), while retaining the near-surface stoichiometry, especially in IBr/Ar plasmas. There was little change of surface smoothness over a wide range of plasma compositions for Gacontaining materials in both ICl/Ar and IBr/Ar plasmas, (e.g. GaAs), while there was a window region with about 25–50% of IBr in IBr/Ar plasmas to maintain good morphology of In-containing semiconductors like InP. Selectivities of 4–10 over mask materials such as SiO2, SiNx, and W were typical in ICl/Ar plasmas.

Photoemission of the Oxidation of Cerium Overlayers on GaSb(110) Surface

We have used x-ray photoelectron spectroscopy to study the oxidation of cerium overlayers on a semiconductor GaSb(110) surface. A GaSb(110) sample covered with 10 monolayers Ce was used to adsorb oxygen. When the exposure of O2 was up to 50 L, the oxide of cerium, Ce2O3, began to change into unstable CeO2. The dissociation of CeO2 resulted in strong oxidation of the substrate. The main products are Ga2O3, Sb2O3, and then Sb2O5. After annealing, a part of the oxygen atoms transferred from cerium dioxide toward Ga and Sb.

Polariton Effective Mass and Spectral Density in III-V Semiconductors Doped with an Ordered Chain of Identical Two-Level Atoms

We study the polariton effective mass and spectral density of III–V semiconductors doped with an ordered chain of identical two-level atoms. The polariton spectrum in these semiconductors has an energy gap which is caused by photon coupling to optical phonons. We found an impurity band within the energy gap when the resonance frequencies ω0 of the two-level atoms lie in the polariton energy gap. We calculated the effective mass of a polariton in this impurity band as a function of interatomic distance. The polariton spectral function is also calculated as a function of the interatomic distance. Numerical calculations are performed for GaAs, GaSb, and InAs semiconductors. It is found that as the interatomic distance increases, the polariton energy band width decreases. It is also found that the effective mass of the polariton is hole-like and its magnitude decreases as the interatomic distance increases.

Dry etching of III-V semiconductors in IBr/Ar electron cyclotron resonance plasmas

IBr/Ar plasmas were found to be promising candidates for room temperature dry etch processing of the III-V semiconductors GaAs, AlGaAs, GaSb, InP, InGaAs, and InSb. Results showed fast etch rates (∼3,000A/min) at high microwave power (1000W) and good surface morphology (typical root mean square roughness ∼2 nm), while retaining the near-surface stoichiometry. There was little variation of surface smoothness over a wide range of plasma compositions for Gacontaining materials. By contrast, there was a plasma composition window of about 25–50% of IBr in IBr/Ar plasmas for maintaining good morphology of Incontaining semiconductors like InP. Etch rates of the semiconductors generally increased with microwave power (400-1000 W) and rf power (50-250 W), whereas there was little dependence of the rates on the increasing percentage of IBr in the IBr/Ar plasma composition above 30% IBr for In-based, and 50% IBr for Ga-based materials. Those results show the etch rates over 30% of IBr in IBr/ Ar are desorption-limited. Photoresist masks do not hold up well to the IBr under ECR conditions, resulting in poor profile control, whereas SiNx offers much better etch resistance.

Bulk Amorphous GaSb Semiconductors Prepared by Thermobaric Treatment: Formation and Properties

AbstractThe multistage process of solid state amorphization and subsequent crystallization of the quenched “white tin” high pressure phase of Ga‐Sb alloys containing 20 to 80 at% Sb was studied at ambient pressure by differential scanning calorimetry. The heats of both amorphization and crystallization were exothermic and equal to (3.5 ± 0.5) and (8.3 ± 1.0) kJ/mol, respectively. Formation of the bulk amorphous alloys free of any crystalline inclusions was observed for compositions with 47.5 to 52.5 at% Sb. The structure of the amorphous GaSb produced by solid state amorphization was studied by neutron diffraction. It is found to be nearly identical to that of a sample prepared earlier by sputtering.

Electrochemical growth of GaSb and InSb for applications in infra-red detectors and optical communication systems

The low-temperature electrochemical deposition of GaSb and InSb semiconductors from aqueous electrolytes has been investigated. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM) have been used to study the deposits' crystallographic and stoichiometric characteristics. Thin films of GaSb and Sb mixtures have been produced, stoichiometric control being limited by the concurrent evolution of H 2 and SbH 3. Mixtures of InSb with either Sb or In, and also mixtures of In, Sb and InSb have been grown. The type of substrate used was seen to affect the stoichiometry of the deposits. The results indicate that there are kinetic barriers to the formation of stoichiometric InSb under the conditions employed.

Analysis of the phase signal in reflection anisotropy spectroscopy

In this study the analysis of reflection anisotropy signals reveals that an unusual behaviour of the phase signal may occur in the presence of weakly anisotropic surfaces. It will be shown that the measured lineshape has to be considered with extreme care if a single-phase lock-in amplifier is used in the experimental set-up. It not only depends on the sample properties but is also influenced by the experimental conditions, in particular the signal phase, which is usually adjusted for maximum signal before spectra are taken and then fixed during measurement. For this purpose the reflection anisotropy spectra are compared with those of the phase for various semiconductor systems. Ideally one would expect the phase signal to change by 180 degrees whenever the reflection anisotropy signal changes sign. On the contrary it was found that the phase spectra, e.g. from the cubic semiconductor GaSb(100), exhibit continuous phase shifts near the zeros in the reflection anisotropy spectra when measuring the signal at twice the modulation frequency. The reflection anisotropy spectra may therefore be significantly different if measured with distinct phases. Theoretical considerations and further experiments reveal that this effect is likely to be caused by partial polarization, which is hard to avoid in any experimental set-up.

Estimation of activity data for the Ga-Sb, Ga-S and Sb-S systems regarding the doped GaSb semiconductor crystals

Abstract

Nature of semiconductor-to-metal transition and volume properties of bulk tetrahedral amorphous GaSb and GaSb-Ge semiconductors under high pressure.

Electrical properties and compressibility of bulk amorphous semiconductors $a\ensuremath{-}{(\mathrm{GaSb})}_{1\ensuremath{-}x}{({\mathrm{Ge}}_{2})}_{x}(x=0 \mathrm{and} 0.27)$ were investigated at high pressure. Discontinuous crystallization of $a\ensuremath{-}{(\mathrm{GaSb})}_{0.73}{({\mathrm{Ge}}_{2})}_{0.27}$ occurs at 4.7 GPa. In $a\ensuremath{-}(\mathrm{GaSb})$ the continuous volume anomaly occurs at 3-7 GPa, whereas the semiconductor-to-metal transition occurs at 3-4 GPa. Metallization of $a\ensuremath{-}(\mathrm{GaSb})$ occurs by the percolation mechanism involving interaction of nanoregions with higher coordination. Bulk moduli of amorphous compounds at normal pressure are less (35 and 40 GPa for $x=0 \mathrm{and} 0.27$, respectively) than that of crystalline (GaSb) (55 GPa) and exhibit strong softening long before the transitions.

A Low Temperature, Solution Phase Synthesis of III-V Semiconductor Nanocrystals

ABSTRACTNanocrystalline materials have been intensely investigated in the recent past due to the novel properties associated with size-quantized particles. We have developed a new method for high yield, solution phase synthesis of nanocrystalline III-V semiconductors which eliminates the use of substituted or unsubstituted Group V hydrides and Group III alkyls. Our approach consists of in situ syntheses of (Na/K)3E (E = P, As, Sb) in aromatic solvents and subsequent reactions of these pnictides with Group III halide solutions in coordinating solvents. The nanocrystalline III-V semiconductors GaP, GaAs, GaSb, InP, InAs and InSb are readily prepared in a wide range of particle sizes (4–36 nm) and in high yields. The resultant Ill-V materials have been characterized by XRD, EDXA, TEM and elemental analyses.