M. P. Yakubenya

Preparation and properties of epitaxial ZnGeP2 films

Thermodynamic analysis has been applied to the vapor over a ZnGeP2 crystal when the chlorine source is provided by ZnCl2. ZnGeP2 film growth has been examined and the electrophysical and photoluminescence parameters have been measured. All these autoepitaxial films have the chalcopyrite structure, while those parameters are determined by the defects and the substrate orientation.

PREPARATION AND INVESTIGATION OF SOME PROPERTIES OF EPITAXIAL LAYERS OF THE SOLID SOLUTION SYSTEM

In this paper we give the experimental results of an investigation of the growth process, morphology, structure, and composition of epitaxial layers of the solid solution system ZnGeP2-GaP. It is established that the chemical transfer mechanism for ZnGeP2 in a closed system with the transport agent ZnCl2 is analogous to the transfer mechanism of binary semiconductors and takes place with the decomposition of the compound into its elements. It is demonstrated that when ZnGeP2 is deposited on substrates of GaP monocrystalline films of the solid solution ZnGeP2-2GaP are formed, the composition of which varies along the thickness of the film from 1∶3 at the boundary with the substrate to 1∶1 in the stationary region for the boundary. The films have a zinc blende structure given by the replacement of Zn and Ge in the sites of the cation sublattice of ZnGeP2 by gallium, which enters into the gas phase from the substrate during its gas etching before the start of the growth.

Interphase interactions in a Pd-GaAs system and their effect on electrical properties of schottky-barrier structures I. effect of heat treatment on characteristics of GaAs-Pd/Ni contacts

The electrical characteristics of surface-barrier GaAs-Pd/Ni structures and the physicochemical interaction processes at the metal-semiconductor boundary were comprehensively investigated in relation to heat treatment in various atmospheres. X-Ray structural analysis showed that in the investigated system metallurgical reactions begin at 300–350‡C: Unstable intermediate phases (presumably Pd2Ga) are formed. At 400–550‡C all the palladium is converted to the bound state and the intermetallic compound PdGa is formed. The phase changes have no significant effect on the properties of diode structures fired in a hydrogen atmosphere. Heating in vacuum leads to degradation of the contact parameters at 300‡C or more. This effect is attributed to penetration of oxygen to the interface during formation of the intermediate phases.

Electron microscope investigation of the morphology of the etched surface of gallium arsenide

An investigation was made of the micromorphology of the surface of GaAs single crystals produced by sulfuric acid etching. The observed acicular structure is highly stable to the reagents used to remove oxides and metals from the GaAs surface (HF, Trilon B, etc.) but can be removed mechanically. It is shown that the microstructure parameters depend on the ratio of the etchant components and the dopant level of the specimen. It is assumed that the distribution of the structural elements (columns) reflects the nature of the distribution of the alloying dopant in the crystal. Adsorption processes are taken to be responsible for column formation on the surface.

Structure and properties of epitaxial layers of InxGa1−xAs grown from the gas phase

A study has been made of the dependence of the crystal lattice parameter and the structural perfection of epitaxial layers of InxGa1−xAs on substrates of GaAs and InP and on the composition of the solid solution. The electrophysical properties of layers of various compositions have been studied. From measurements of the photoluminescence spectra, a determination has been made of the dependence of the width of the forbidden band on the composition of the layers.

Solid-state recrystallization processes in Ni-GaAs and Pd-GaAs structures

Electron microscopy, reflection electron diffraction, and x-ray diffraction analysis are used to investigate solid-state recrystallization processes in the Ni-GaAs and Pd-GaAs structures at room temperature and during heat treatment in a hydrogen atmosphere. Contacts were produced by electrodeposition of the metal (Ni, Pd) onto the (111) A surface of a GaAs ingot. It is shown that physical and chemical reactions at Ni-GaAs and Pd-GaAs contacts occur even at room temperature, with the formation of chemical bonds between the metal and both gallium and arsenic. The phases formed at the contacts upon annealing in a hydrogen atmosphere correspond to those expected from the phase diagrams, and solid-state recrystallization occurs under the strong orienting influence of the substrate.

Investigation of the structure and properties of sulfur-doped expitaxial gallium arsenide layers

ConclusionThe electrophysical properties, the lattice constant, and the structure of sulfur doped epitaxial gallium arsenide layers were investigated using a complex of methods. The experimental data indicate that the sulfur atoms can exist in the GaAs lattice simultaneously in the number of states, namely, in the form of substitutional and interstitial solid solutions, as well as in the form of presegregations or second phase segregations. The concentration of interstitial sulfur atoms increases with the overall-sulfur content in the layers. At the maximum sulfur doping level second phase segregations are formed in the layers, which leads to an anamolous decrease in the lattice constant and the electron mobility.

Investigation of anisotropic effects in vapor epitaxy of indium arsenide. I. Anistropy of growth rate and surface microrelief

Kinetic (growth rate), optical, and electron-microscopic (surface relief) studies were made of the process of formation of homoepitaxial films of InAs in a chloride gas-transport system. It was found that the (111)A and B surfaces of indium arsenide and their vicinals grew by the step-layer mechanism, whereas the (001) surfaces and those inclined from them grew by the normal growth mechanism. Two types of defect were observed on the growth surface of homoepitaxial InAs films: a) defects nucleated on the substrate; b) humps formed on the surface during the final stage of the process.

Nondislocation etch pits in gallium arsenide obtained by vapor-phase epitaxy

The effect of the vapor-phase epitaxy conditions on the formation of small nondislocation etch pits (SEP) in autoepitaxial gallium arsenide layers was investigated by the oblique-section metallographic technique. The investigations showed that SEP are found in n-type low-dislocation layers and are located directly in the junction region. The width of the SEP region depends on the concentration and type of dopant in the source, the type of substrate, and also on the concentration of transport agent at the system inlet. The formation of SEP in the layers involves impurity segregates of the second phase.

Electron microscopy of growth surfaces on epitaxial films

It has been found that the final stage in the growth of an epitaxial film is decoration of the surface; to obtain objective information on the growth relief, it is necessary to examine at least two successive carbon replicas.