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  • Formation of Island Nanostructures by Sublimation Epitaxy in Electronic Technology

    The possibilities of a little-studied method for obtaining nanosized materials of electronic engineering with a given substructure, the zone sublimation epitaxy (ZSE) method, are discussed. In the work, it is combined with the method of gradient liquid phase epitaxy (GLE). A specific feature is mass transfer in a two-phase medium (a solid substrate and an inert gas phase acting as a transport medium) with preliminary deposition of a matrix layer formed from the melt. A feature of the sublimation process in the study was the crystallization of low-melting iron-silicon eutectic. A mathematical model of the process was proposed and compared with the experimental results. Island structures of the composition silicon (more than 90%), iron (up to 8%) and chromium (about 1.5%) have been obtained. Their parameters and size distribution were studied. A Solver-HV scanning probe microscope and a Quanta-200 scanning electron microscope were used. The study shows that the use of sublimation transfer transients makes it possible to reproducibly form doped silicon nanolayers and transform them into regular mesostructures.

    Keywords: microsize growth cell method, zone sublimation epitaxy, gradient liquid phase epitaxy, island nanostructures

  • GaInAsBi epitaxial films based on indium arsenide - a new material for infrared lighting technology

    The results of a theoretical and experimental study of the synthesis of GaInAsBi thin-film structures formed on InAs substrates in the field of a temperature gradient are discussed. The features of interfacial interaction in the In-As-Sb system in the presence of isovalent solvents (In, Bi) have been studied. The values ​​of the interaction parameters and the distribution coefficients of the system components are determined. Optimal technological modes for obtaining InAs-based heterostructures are presented. The properties of the surface of epitaxial layers are studied experimentally. It was found that the main control parameters are the temperature of thermomigration and its gradient. It is shown that the synthesized semiconductor materials can be effectively used in electronic devices of a new generation - electro-optical modulators and supersensitive sensor elements.

    Keywords: epitaxial structure, crystallization, recrystallization, melt, segregation coefficient, organometallic compound, voltage sensitivity, near infrared range, solid solution, optical characteristic

  • Predicting the state of a stochastic system on electrified railways

    Stochastic systems are systems in which changes are random. In which the predicted values depend on a probability distribution. An example of a stochastic system in a power system, the operation of which is affected by many random factors, their analysis and control will allow you to control the safe cycle and reliability of operation. Currently, there are methods and mathematical tools that allow us to estimate the likelihood of any phenomenon and situation with acceptable accuracy, however, they are practically not used to solve this problem on electrified railway transport. Therefore, the work summarizes the existing methods of probabilistic forecasting, and gives recommendations on their application to solve the existing problematic of the issue. Further, the paper shows a method for determining the probability of failure of a constituent structural element of any, arbitrarily complex, stochastic system, to which the contact network of electrified railways belongs. In the conclusion of the work, an elementary method-oriented software tool with the functional purpose of automating statistical methods for solving problems of primary data processing and calculating elementary statistics in the process of risk management is proposed, as well as loading and maintaining a database that is subsequently oriented to the principles of machine learning.

    Keywords: electrified railways, stochastic systems, operational reliability, probability of failure, forecasting

  • Predictive analysis of the state of objects as a new strategy for the technical operation of electrified railways

    Stable reliability characteristics are a guarantee of non-emergency operation of electrified railways, undoubtedly, the profitability of transportation processes is growing. The article proposes an innovative method for determining the characteristics of reliability, with a decrease in the risk of failure or emergency. Electric traction used in most of the railroad landfill. It is necessary to consider the issues of reliability of the power supply system to predict the state of the system and study the patterns of interaction that affect system and non-system communications. Therefore, we will pay special attention to the reliability of the power supply system; in order to predict failures, first of all, it is necessary to know the patterns of interaction and patterns that affect system and non-system communications. The danger of risk directly depends on the number and duration of failures. In the power supply system, a huge number of heterogeneous and differently distributed objects, nodes and elements operate in different modes and are susceptible to different operational influences.Therefore, the work summarizes the existing methods of probabilistic forecasting, and gives recommendations on their application to solve the existing problematic of the issue. Further, the paper shows a method for determining the probability of failure of a constituent structural element of any, arbitrarily complex, stochastic system, to which the contact network of electrified railways belongs. In the conclusion of the work, an elementary method-oriented software tool with the functional purpose of automating statistical methods for solving problems of primary data processing and calculating elementary statistics in the process of risk management is proposed, as well as loading and maintaining a database that is subsequently oriented to the principles of machine learning.

    Keywords: electrified railways, predictive analysis, operational reliability, probability of failure, forecasting

  • Clarifying the criteria for the application of an automated anti-freezing system on contact network wires

    The increasing load on the power supply system of electrified railways leads to higher requirements for reliability of power supply. Clarifying the criteria for the operation of the automated system to combat ice formation on the wires of traction power supply to railways in difficult weather conditions is an urgent task aimed at improving the reliability of uninterrupted power supply of rolling stock

    Keywords: ice melting, calculated coefficients, selection of optimal parameters, traction power supply system

  • The structure of epitaxial layers of narrow-gap solid solutions and compensation of defects

    The paper contains an analysis of the results of experiments on obtaining radiative structures based on gallium antimonide, formed by the method of thermal melt migration in a semiconductor matrix. The epitaxial process modes within the selected range were optimized for such parameters as the wavelength corresponding to the fundamental transition, a small lattice discrepancy, a small discrepancy in the coefficients of thermal expansion of the growing TP and the matrix. An original effect is described - an increase in the solubility of the Bi content in solid solutions, isoperiodic binary compounds A3B5 under conditions of a gradient temperature field. This effect allows a wide variation in the optical parameters of the element base of instruments based on solid solutions of GaSbBi / GaSb. The mechanisms of the generation of dislocations in a crystallized solid solution and the features of electrophysical and photoelectric parameters are analyzed. A structural solution of a light-emitting diode with strip geometry is proposed.

    Keywords: solid solutions, recrystallization, gradient liquid-phase epitaxy, thermomigration, indium antimonide-bismuthide, melt thickness, temperature gradient, components, growth coordinate, epitaxial layers

  • Physical properties of multicomponent narrow-gap solid solutions with mesostructure authors

    In this paper, the modeling of phase equilibria in multicomponent systems of A3B5 compounds was carried out and the compositions of the liquid phase equilibrated with a given solid solution were calculated. A model of excess thermodynamic functions is used, which takes into account the formation of associates in the melt near the solidus temperatures. The developed algorithm allows solving a direct problem (in which the input parameters are the growth temperature of the layers and the composition of the solid phase corresponding to the expected instrument characteristics) and the inverse problem (the growth temperature and composition of the solid solution are sought for the given liquid phase). The limiting concentrations of the alloying components, arsenic and bismuth, are determined. The structural and electrophysical characteristics of multicomponent semiconductor A3B5 heterosystems are discussed, the solid solutions of which crystallize from the liquid phase in a gradient thermal field. The mechanism for introducing impurities into the lattice of epitaxial layers of multicomponent solid solutions is described for the first time. With an increase in the thickness of the crystallizable film, the thermodynamically equilibrium substitution by antimony bismuth atoms is completed and the introduction of Bi atoms into the interstices takes place. The interaction of neighboring atoms with the valence electron shells of Bi becomes more symmetrical, which causes an increase in concentration. The concentration of film defects near its rear surface also increases. The obtained values of electrophysical parameters make it possible to draw a conclusion about the instrumental suitability of the materials under study.

    Keywords: solid solutions, mesostructure, antimonide, alloying, liquid phase, phase transformations, binary compounds, associates, lattice constant, multicomponent systems

  • Optimal physical parameters choice of ice melting in the contact network DC

    The physical process features at the point of contact of the electric rolling stock current collector and the contact wire in the system of traction power supply of DC Railways are considered. The choice of parameters of the combating icy frost formations on the wires of the contact network by melting ice method is justified

    Keywords: physical process, an electric arc, melting of ice, the estimated coefficients, the choice

  • Physical properties of light-emitting sold solutions, isoperiodic gallium antimonide

    The paper contains an analysis of the results of experiments on obtaining radiative structures based on gallium antimonide, formed by the method of thermal melt migration in a semiconductor matrix. The epitaxial process modes within the selected range were optimized for such parameters as the wavelength corresponding to the fundamental transition, a small lattice discrepancy, a small discrepancy in the coefficients of thermal expansion of the growing TP and the matrix. An original effect is described - an increase in the solubility of the Bi content in solid solutions, isoperiodic binary compounds A3B5 under conditions of a gradient temperature field. This effect allows a wide variation in the optical parameters of the element base of instruments based on solid solutions of GaSbBi / GaSb. The mechanisms of the generation of dislocations in a crystallized solid solution and the features of electrophysical and photoelectric parameters are analyzed. A structural solution of a light-emitting diode with strip geometry is proposed.

    Keywords: thermomigration, solid solutions, gradient epitaxy, diode with fine mes, gallium antimonide, fundamental transition, photoluminescence spectra