Study of the Surface Processes in Vapor-Phase Epitaxial GaAs: Asymmetric Trapping of Atoms at the Step

Experimental proofs of asymmetric trapping of atoms at the growth step in vapor-phase epitaxy of gallium arsenide in the GaAs–AsCl₃–H₂ system are given. The data obtained confirm the important role of the surface diffusion mass transfer in the growth of epitaxial GaAs layers on vicinals in the neighborhood of (111)A. The effective diffusion length is estimated.     

Conditions for obtaining backward collinear isotropic acousto-optic interaction in germanium and iodic acid crystals

The possibility of experimentally obtaining backward collinear isotropic acousto-optic interaction based on bulk ultrasonic waves and terahertz electromagnetic waves is considered. The magnitudes of the acousto-optic figure of merit and the corresponding acoustic frequencies are calculated for the basic crystallographic axes in germanium and iodic acid crystals. The acousto-optic parameters of both crystals are compared.     

Doping mechanisms of gallium arsenide with tin in gas phase epitaxy processes

A thermodynamic calculation of the equilibrium composition of the gas phase Ga-As-Sn-Cl-H system was carried out. An estimate of the impurity composition of adsorbate layers was made. A study of the electrophysical and photoluminescent properties of tin-doped GaAs epitaxial layers was conducted. From a comparison of the calculated and experimental data, it follows that the dependence of trapping mechanisms for tin on the conditions of epitaxial growth corresponds to changes in the gas phase and adsorbate layer compositions. A mechanism is proposed in which the introduction of impurities into the layers in elemental and complex forms occurs due to capture of atomic and diatomic tin adsorbed on the surface.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 37–40, June, 1990.     

Influence of thermal processing on the properties of Sn-doped GaAs epitaxial layers

The influence of annealing at a temperature of 750–830°C on the electrophysical, luminescent, and structural characteristics of GaAs layers doped with various concentrations of tin is studied. It is shown that, for low doping levels, the layers possess properties with high thermal stability. During annealing, one observes a lowering of the concentration of electrons, a reduction of the lattice periodicity, and a change in the photoluminescence spectra of strongly-doped layers, which is explained by the process of the formation of complexes and by the decomposition of supersaturated solid solutions of impurity dopants.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 54–59, January, 1989.The authors express gratitude to M. P. Yakuben for x-ray topographical studies.     

Effect of dopant type on the formation of the growth relief of gallium arsenide in a chloride gas-transport system

The effect of dopants (zinc, tellurium) on the microrelief of the growth surface of autoepitaxial gallium arsenide layers is considered. It is shown that the type of dopant exerts a considerable effect on the characteristics of the microstep structure of the surface; the reasons for the reconstruction of the relief under the action of the dopant are analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 44–48, January, 1976.     

Application potential of paratellurite and iodic acid crystals for acousto-optics in the Terahertz range

The possibility of applying paratellurite, iodic acid, and lithium iodate crystals in acousto-optics in the THz range has been investigated. The transparency windows of these crystals and their refractive indices in the THz range have been determined. The acousto-optic figures of merit of these materials are calculated for different acousto-optic interaction geometries.     

Anisotropy of impurity trapping by epitaxial layers of gallium arsenide near singular faces with different chlorine and tellurium pressures

Trapping of impurities near the poles <111>A, <110>, and <001> was studied. It was found that the rates of trapping of the impurity near the singular faces behaved differently when the chlorine and tellurium pressures were increased. A singular maximum appears on the (111)A face, a singular minimum remains on the face (110), and the face (001) corresponds to the point on the smooth section of the curve which is unsymmetrical with respect to the pole. The results are interpreted based on the assumption of the formation of an impurity-main-material complex on the surface of the growing crystal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii,. Fizika, No. 2, pp. 92–96, February, 1985.     

Growth and impurity-trapping kinetics in sulfur-doped gallium arsenide epitaxy

Measurements have been made on the effects of crystallization conditions on the growth rates and electrophysical parameters for sulfur-doped epitaxial gallium arsenide films: gas speed, supersaturation, and deposition temperature. There is a correlation between the impurity concentration and the growth rate. The results are discussed from a model that incorporates interaction between impurity atoms and matrix ones.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 71–76, January, 1988.