2000   Vol.1   №1

    Randomly rough surfaces have been prepared by original technology used at chemical doping urfaces by metals (metallization or island metal film growth). The morphology of such disordered microrelief) GaAs (111) surfaces were examined by atomic force microscopy (AFM) and multi-angle-of incidence ellipsometry (MAI). The resulted images were processed to obtain the local and statistical roughness parameters. The smooth character of investigated disordered surfaces has been confirmed by comparison of experimental relief-induced changes of polarization angles with the calculated ones obtained by using the perturbation theory. Optical parameters of equivalent surface absorbing layer with flat interfaces obtained with using the effective medium approximation (EMA) theory in 3D model allow us to describe the optical properties of disordered surfaces.

    Keywords: chalkogenide of lead, atomic defects, crystal chemistry, two-temperature annealing.

    Non-stationary temperature distributions in the electron and phonon subsystems of quasiparticles are calculated with taking into consideration of electron-phonon energetic interaction in the semiconductor submicron film. The external source of non-equlibrium perturbation is the modulated and pulsed laser irradiation, which energy is completely converted into heat on the surface of the film. It is shown that the temperature distributins in the electron and phonon gases are formed independently in the films with the thicknesses smaller than the cooling length. Dynamic electron temperature is quasistationary in the non-degenerated semiconductor materials under the periodic thermal perturbations with the frequencies less then characteristic frequency of energy change in the electron subsystem. The propagation of thermal waves is possible in the phonon subsystem. Under the pulse perturbation the non-equilibrium temperature is formed mainly in the electron gas. Characteristic lengths and times of changes of the electron and phonon temperatures are obtained, the criterias for the high and low modulation frequency as far as for long and short pulses are stablished in the both cases. The possibility of electron temperature detecting in the pulse regime by thermoelectric methods is examined.

    Keywords: chemoepitaxy, supersaturation, mechanism, habitus, nucleation, twinning.

    Non-stationary electron and phonon dynamic temperature distributions is obtained with the system of energy balance equations for electron and phonon subsystems of nondegenerate semiconductors of submicron length when the generation and recombination processes are absent. The modulated laser beam of radiation converted into heat in the bulk of the sample is in the role of an external energy source. It is considered the series of partial cases in correspondence to relationships between the characteristic lengthes of the problem. It is analysed the posibilities of determining both the electron parameters of semiconductors (diffusivity, the bulk and surface heat conductivity) and the light absorption coeficient.

    The investigation have been done on the study of the reductant oxide iron by different reductants. It has been defined, that the reduction process is being fullbilled in one or two reactional zones, depending on the conditions. For the description of the reduction process definding nonstoichiometry and the defects origin crystalquasychemical model has been used.

    Keywords: crystalquasychemical mechanism, nonstoichiometry, antistructure, hematite, magnetite, wustite.

    Diamond-like carbon films, deposited by direct ion beam deposition method using C₆H₁₄ and mixture of C₆H₁₄ and H₂ and were irradiated by low energy electron and ion beams, have been investigated by Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and electrical measurements. The variation of the D- and G-line peak position and integrated intensity ratio (I_D/I_G) in the Raman spectra has shown that these films are amorphous with mixture of sp² and sp³ bonds. It has been found that with increasing substrate temperature during deposition time the DLC films are more graphite-like, and with increasing hydrogen content sp² clusters are smaller and more disordered. The ion irradiation has more modified surface layer. Electron irradiation of the samples coated by SiO₂ can heat the sample because of big current densities and with electric break-down phenomenon can increase sp³ bonds concentration and decrease disorder of diamond clusters.

    Keywords: DLC films, Raman spectroscopy, ion bombardment, electron irradiation.

    We examined the n-p-transition in the crystals of PbSe at the twotemperature anneal. The experimental result are explained by the creation of own atomic defects: interstitial atoms of lead (Pb_i⁺), and vacancies of lead (V_Pb^-). The received analytical expressions describe the n-p-transition and also a dependence of concentration of charge carries on the temperature of anneal and partial pressure of the vapors of selenium. The technological conditions of formation the PbSe crystals with electric properties set before hand are determined.

    Keywords: crystals PbSe, defects, balance constant, n-p-transition, anneal.

    The structure investigations of amorphous films obtained from complex halcogenides A^IBi₃C^VI₅ (A^I - Li, K, Rb; C^VI - S, Se) were carried out by transmission electron microscopy and electron diffraction. It was established the microstructure peculiarities, in particulary the column growth structure of amorphous layers depending on the preparation conditions. The influence of chemical composition of evaporated material on the average column size was found.

The column structure formation mechanism based on the model of soft three-centered bonds in the hard covalent network was suggested.

    Keywords: halcogenides compounds, amorphous films, condensation, column microstructure.

    Is investigated the main dispersion’s mechanisms of the electron condactivity in the crystals of n-PbTe at the 4,2K with parabolic and unparabolic laws of the disperssions for the Kane’s model. It’s shown the role of the Coulomn’s potential of vacansion is one of the main at the low concentrations. The shortinfluence potential is main at the high concentrations for the both models.The obtain results are shows, that parabolic law of the disperssion is good worked at the low and medium concentrations. The unparabolic disperssion’s law must be used at the high concentrations.

    Keyword: telluride of lead, Holl’s mobility, disperssion, band’s model, time of relaxation.

    The influence of the small addition of Bi on the structure, electrophysical properties and optical ones of GeSe thin films has been investigated. Using electronographic studies it is shown that (GeSe)_1-xBi_x (0? x? 0,15) films are amorphous and their structure can be described in the frame of model, which is usually uses for solid GeSe-Bi₂Se₃ solutions. Electroresistivity increases when Bi-atoms are added. At the same time optical gap width E₀ decreases and reciprocal slope of exponential region of absorption edge d(hn )/dlna increases.

    Green’s function method is used to investigation of the energy spectrum and its damping for the lattice electrons with the random energy at the sites in the constant magnetic field. The analytic expression for the spectrum and its damping for the 2-chains system has been obtained. The numerical analysis for the 10-chains system graphically presented.

    The current-voltage characteristics of epitaxial p-Si, amorphous Ge₃₃As₁₂Se₅₅ films and Ge₃₃As₁₂Se₅₅ – p-Si heterostructures with injection (Sb) and blocking (In) contacts are investigated. It this estableshed, that current-voltage characteristics of In–p-Si and In– Ge₃₃As₁₂Se₅₅ junction may be described in the framework of simple Shottky model. By the use of injection contacts the current through the amorphous film and heterostructure at direct bias is restricted by spatial charge, which appears in the film; the current through the heterostructure at reverse bias is determinated by the barrier height on the amorphous film – p-Si interfase.

    The model of defect subsystem of crystal with the simultaneous existence of singly and doubly charged interstitial atoms and vacancies in the metallic sublattice of lead chalcogenides is proposed. On the basic of analysis of the general and “partial” conditions of electroneutrality the dependencies of charge carriers’ and defects’ concentrations upon the chalcogen’s pressure have been investigated under the realization of double temperature annealing.

    Keywords: lead chalcogenides, defects, constants of equilibrium, crystal chemistry.

    In this article briefly represented a crystalloquasichemical approach to the study of point defects of nonstoichiometry, doping and formation of solid solutions for halcohenides of plumbum.

    Keywords: PbTe-SnTe solid solutions; doping with In; thermoelectric characteristics.

    Experimental data on peroxide-induced crosslinking of high-pressure polyethylene have been treated by means of logarithmic scale method. The effective yield of crosslinking has been found to be valua 0,8 to 1,8 mole per peroxide mole and the effective field of scission – 0,3 to 1,0.

    In work the results of researches of resistance against corrosion in critical for titanium solutions of sulphuric acid after it saturation of diffusion by iron and carbon in various modes of processing are given.