Effects of gas flow speed and chlorine concentration on tellurium uptake in gas-phase epitaxy of gallium arsenide

A comparison is made between the growth kinetics of gallium arsenide films and the uptake of tellurium in gas-phase epitaxy in a chlorine system. The ratelimiting stages for both processes are the same and are associated with diffusion through the boundary layer and the rates of surface processes (adsorption and desorption).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 18–21, November, 1982.We are indebted to A. I. Saprykin for performing the mass spectrometry of the gallium arsenide films.     

Complexing of tellurium-doped gallium arsenide in gas-phase epitaxy

The effect of the conditions of gas-phase epitaxy on complexing in tellurium-doped layers of gallium arsenide is studied. Measurements of the intensities of the corresponding photoluminescence lines were used to estimate the concentration of optically-active complexes. A correlation was found between the processes involved in complexing, the growth velocity, and impurity trapping in the layers. The determining role of the surface structure in the formation of complexes, including impurity atoms, is demonstrated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 96–100, February, 1985.     

Study of the Elementary Growth Processes During Vapor-Phase Epitaxy of Semiconducting III–V Compounds

A review of studies performed at the V. D. Kuznetsov Siberian Physical-Technical Institute at Tomsk State University and aimed at obtaining detailed information on the elementary growth processes proceeding at the crystallization front during vapor-phase epitaxy of semiconducting III–V compound films is presented in the paper. The general approach to the problem and methods of its solution are described. Results of investigations of the adsorption layer composition, surface diffusion processes, and incorporation of growth components into a crystal are presented. The mechanism of epitaxial layer growth in semiconducting III–V compounds is discussed.     

Kinetic model of growth of GaAs nanowires

A kinetic model of growth and formation of the crystal structure of gallium arsenide nanowires by molecular beam epitaxy on surfaces activated by Au drops is developed. The thicknesses of alternating layers of cubic and hexagonal phases formed due to fluctuations of the solution composition in the drop are calculated and compared with experimental data.     

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.     

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.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 2, pp. 70–74, February, 1985.The authors are grateful to L. G. Lavrent'eva for useful discussion of the results, G. A. Aleksandrova, and L. P. Porokhovnichenko for supplying the specimens for the investigation and I. G. Lyapichev for carrying out the electron-probe microanalysis.     

Thermodynamic characteristics of phase-transition intensity in describing crystallization processes

It is shown that under realistic conditions the processes of crystallization of complex systems can be described using effective rate functions. Being a thermodynamic stimulant of the process, these functions enter as a composite factor in all equations for the crystallization redistribution of the composition and in the equations for the rate of motion of the liquid zone in the zone-melting method with a temperature gradient. The values of the crystal growth rates achieved are described using these functions. To supplement the results of the theory of concentration supercooling, estimates are obtained of the limiting rates of temperature drop in liquid epitaxy using Nelson's method of forced cooling. The result obtained is found to be in agreement with published experimental data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 106–111, January, 1978     

Structure,electron states,and electrophysical properties of gallium arsenide surfaces

Conclusion This review has analyzed studies of the surface physics of monocrystalline gallium arsenide as of 1978. Special attention has been given to peculiarities in structure, lattice dynamics, and the spectra of surface electron states in atomically pure and real GaAs surfaces as compared to Ge and Si. These peculiarities manifest themselves in the specifics of the electrophysical properties of GaAs surfaces, quasisurface conductivity, capacitance of structures with a potential barrier, nonequilibrium transfer processes, radiant processes, and other phenomena characteristic of polar noncentrally symmetric semiconductors. At present the development of gallium arsenide surface physics is proceeding in two directions: 1) study of the micromechanism of electronic processes on atomically pure surfaces; 2) study of the nature and characteristics of various electron-ion processes on a real surface. Important information on the surface can be obtained by study of phenomena in which surface quasiparticles participate — phonons, plasmons, excitons, and mixed polaritons.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 38–51, January, 1980.     

Nanoscale peculiarities of the thermally stimulated surface autosegregation of covalent crystals: Gallium arsenide

Nanoscale changes in the morphology and elemental composition of cleavage surfaces of gallium arsenide crystals, which arise due to thermally stimulated surface autosegregation, are investigated in detail and systematized. It is shown that, depending on the annealing conditions (temperature, duration, and evacuation), gallium arsenide dissociates, forming submicron nonstoichiometric layers on the surface or local phases of arsenic, gallium, and gallium oxide. The mechanism and nature of autosegregation are determined by the competing processes of arsenic sublimation and its surface diffusion with an activation energy of ～31 kJ/mol. The migration of arsenic atoms is described with the help of a crystallochemical model. The nanomorphology of the surface phases includes arsenic and gallium nanoparticles with sizes of 10-200 nm, their agglomerates, and gallium oxide nano- and microcrystallites combined in plate- and chainlike configurations.     

Epitaxial InGaAs Quantum Dots in Al0.29Ga0.71As Matrix: Intensity and Kinetics of Luminescence in the Near Field of Silver Nanoparticles

Optics and Spectroscopy - Quantum dots of indium gallium arsenide buried in a thin layer of aluminum gallium arsenide were grown by means of molecular-beam epitaxy. The influence of silver...     

Gasdynamic effects during the growth of crystalline gallium nitride via chloride-hydride epitaxy in a vertical reactor

The growth of crystalline gallium nitride during chloride-hydride vapor epitaxy in a vertical reactor is numerically simulated. The effects of a break in the stability of the gas flow and the related changes in the crystal growth characteristics are analyzed; these changes are caused by changes in the flow rates of the gas components and in the crystal position with respect to the source of gallium. Free concentrational convection is found to substantially affect the crystal growth rate distribution over the crystal surface.     

Isothermal liquid epitaxy of variable-gap AlxGa1−xAs films

A mathematical diffusion model is proposed for the isothermal liquid epitaxy which arises when a layer of molten gallium is in contact on its two sides with a substrate of gallium arsenide and aluminum. Computer calculations showed that the thickness of the variable-gap films increases with increasing temperature of the process and increasing thickness of the layer of melt, and that the Al concentration in the films increases monotonically in the direction of growth. The maximal concentration of Al in the solid solution is determined by the amount of Al brought into contact with the melt. Experimental results confirm the theoretical calculations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 38–41, April, 1980.     

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.     

Influence of the Substrate Orientation on the Silicon Capture into A- and B- Sublattices of Gallium Arsenide in Molecular Beam Epitaxy

The influence of crystallographic orientation of the growth surface near (100) and (111)A GaAs singular faces on the silicon capture into A- and B-sublattices of gallium arsenide in molecular beam epitaxy is investigated by the electrophysical and photoluminescence methods. It is demonstrated that the silicon dopand is incorporated into GaAs layers not only as simple Si_Ga donors but also as elemental Si_Ga acceptors and more complex defects, namely, Si_As–V_As complexes. The concentration of defects of different types in layers depends on the orientation of the growth surface, and the amphoteric properties of silicon on the (111)A face are manifested stronger than those on the (100) face.     

Surface chemistry on semiconductors studied by molecular-beam reactive scattering

This Report reviews the use of molecular-beam reactive scattering to study the surface reactions of gas molecules on semiconductors which have relevance to microelectronic technologies. Modern semiconductor fabrication techniques rely heavily on dry processes where gas-surface reactions are the basic premise. This article focuses on the use of supersonic molecular-beam-surface scattering to study the dynamics and kinetics of surface reactions connected with the growth and etching processes on semiconductor surfaces. The discussion on growth processes covers the oxidation of silicon and germanium, the tungsten-hexafluoride-based tungsten deposition, and the organometallic chemical vapor deposition of gallium arsenide. The discussion on etching processes covers the halogen-based etching of gallium arsenide and silicon. An overview of the experimental technique and the underlying principles in surface-reaction dynamics and kinetics is included for readers in the technology area. The potential use of the molecular beams for actual semiconductor materials processing is also discussed.     

Production of Semiconducting III–V Single Crystals: Current Status and Outlook

The current status of and outlook for the worldwide production of semiconducting III–V single crystals, primarily gallium arsenide, are examined. Particular emphasis is placed on improving production technologies and reaching head positions in the vertical crystallization technology.     

Study of the diffusion of gallium and arsenic into germanium during the epitaxial growth of gallium arsenide on the latter

The distribution of gallium and arsenic atomc (as well as the carrier distribution) in the diffusion layer of a germanium surface subjected to the epitaxial growth of gallium arsenide is examined. It is found that the nature of the p-n junction formed in the germanium is determined by the diffusion of gallium as well as arsenic; gallium exhibits an anomalously high rate of diffusion in germanium.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 93–99, January, 1973.     

Development of GaAs Epitaxy from Bulk to Ultrathin Films. Growth for Nanostructure Devices

The effects of stoichiometry on various features of III–V compounds are investigated. It is shown experimentally that the optimum vapor pressure of V elements minimizes the deviation from the stoichiometric composition. Vapor pressure control technology is applied not only to the liquid phase epitaxy and bulk crystal growth but also to the surface reaction in molecular-layer epitaxy. The surface reactions of monomolecular layer growth by using chemical adsorption of precursors were investigated for GaAs, InP, Si, etc. The atomic scale controlled epitaxy of these materials has been studied with the study of surface reaction mechanism. The self-limiting growth in atomic or molecular layer was achieved with doping technology in each materials developed by choosing precursor materials.     

Multimillion Atom Molecular Dynamics Simulations of Nanostructures on Parallel Computers

Scalable space–time multiresolution algorithms implemented on massively parallel computers enable large-scale molecular dynamics (MD) simulations involving up to a billion atoms. Multimillion atom MD simulations are performed to study critical issues in the area of structural and dynamical correlations in nanostructures. Our simulation research is focused on a few semiconductor, ceramic, and metallic nanostructures. These nanostructures systems include: nanometer-scale stress patterns in silicon/silicon nitride nanopixels; self-limiting growth and critical lateral sizes in gallium arsenide/indium arsenide nanomesas; structural transformation in colloidal semiconductor nanocrystals; nanoindentation of crystalline and amorphous silicon nitride films; and dynamics of oxidation of metallic aluminum nanoparticles.     

Component distribution of the solid solution AlxGa1-xAs during zone melting with a temperature gradient of the powderlike source

The component distribution of the ternary solid solution in epitaxial layers of Al_xGa_1-xAs grown by a zone recrystallization method by a temperature gradient during continuous feed maintenance by a powdery source consisting of a mixture of gallium arsenide and aluminum is analyzed theoretically. The possibility is shown of stationary growth of a material of constant composition as well as of epitaxial layers with controllable growing or decreasing aluminum arsenide distributions in the growth direction.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 52–55, February, 1987.In conclusion, the authors are grateful to V. N. Lozovskii for interest in the research and useful discussions.