L. M. Krasil'nikova

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.

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.

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.

Nature of the phase responsible for the formation of SIC-type growth defects during gas-phase epitaxy of III-V compounds

The element composition and crystal structure of a second phase forming growth microdefects were investigated by electron microscopy, reflection electron diffraction, and electron-probe microanalysis at various stages of the gas-phase epitaxy of gallium and indium arsenides. Following chemical-mechanical polishing and gas etching, the elements Cu and Cr were revealed on the substrates; Cu, the element of the III group, and the doping impurity were found on the surface of the epitaxial layers. According to electron diffraction data, after chemical-mechanical polishing the substrate surface is amorphous, following gas etching and epitaxy a second phase in a polycrystalline state is found on the surface. The parameters of its structure are close to those of the basic material and of ternary compounds of the type CuGaX2 and CuInX2, where X=S, Se, Te. The possible sources of the background contamination are analyzed.

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.

Growth mechanism for thin autoepitaxial silicon layers grown in a low-temperature chloride process

Electron-microscope investigations show that in the SiCl4,-H2 system at sufficiently high purity of the substrate surface and the gas-phase mixture in a low-temperature process, morphologically perfect epitaxial layers of silicon grow by a step-layer mechanism. Estimates are given for a number of parameters of the silicon-layer growth surface.

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.

Micromorphology of auto-epitaxial layers of gallium arsenide

The influence of the crystallographic orientation of a substrate and alloying admixture (Zn) on the micromorphology of the growth surface of auto-epitaxial layers of GaAs is investigated. Features of the growth mechanism for layers of different orientations are discussed based on the resulting data and the influence of an admixture on the characteristics of the graduated-layer relief is considered.

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.