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
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
The possibility of increasing the reliability of assessing air pollution through the use of probabilistic methods is shown. Evaluation of quality indicators on a quantitative basis made it possible to find an error of the first and second kind in assessing the quality of the atmosphere. Based on the Bayesian approach, dependencies were obtained for estimating and predicting atmospheric pollution in the area of a city that does not have a stationary post, based on data from stationary posts in other areas.
Keywords: atmosphere quality, reliability of the estimate, probabilistic methods, quantitative characteristic, error of the first and second kind, Bayesian approach, a priori probability, posterior probability, likelihood of a quantity
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
First-principles simulation of ultrathin amorphous carbon films has been performed. Nanohybrid graphene-C60 systems were considered. Total energy calculations were performed using pseudopotential method within density functional theory. Local atomic structure and electronic energy spectrum of the systems were studied. It was demonstrated that fullerene-graphene interaction results in significant deformation of their local atomic structure. Obtained results are in good agreement with experimental X-ray UV spectra of hydrogenated amorphous carbon
Keywords: Phase-change resistive memory, ab-initio simulation, pseudopotential method, Kohn-Sham method, graphene, fullerenes, amorphous carbon, atomic structure, electronic structure, adsorption energy
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
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
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
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
The article discusses the possible causes of pollution of Taganrog Bay of the Azov Sea with oil products for the period 2008-2013. The key factors of pollution were highlighted. Effects of navigation for cotion was evaluated by navigation intensity. Effect of wastewater was evaluated by the number of oil products which fall from municipal drains and wastewater from industrial plants. The data processing of the federal statistical reporting on the influence of the main contamination factors was carried out.
Keywords: oil products, water pollution, average annual concentrations
Information about authors of issue №2 (2014)
Keywords: authors
A voice activity detector (VAD) is a device, which analyses a speech signal and generates the signal corresponding to the period containing only noise. In the present work is offered VAD, which increases the probability of correct detection the presence or absence of human speech.
The correct detection begins with SNR 7-10 dB. The quality of derived speech signal remains the same.
Keywords: voice activity detection, voice activity detector, VAD, silent interval detection, speech, speech signals
A method of expanding the bandwidth and improve the performance of the differential voltage divider – attenuator (AT), which have parasitic capacitance on the outputs C01, C02. Wide range of transmission of the AT provided by introducing a compensation circuit C01, C02, which is achieving data quality indicators. Simulation results of desired are shown.
Keywords: a resistive voltage divider, differential attenuator, the parasitic сapacitance load, speed, upper frequency limit, analog-to-digital converters.
There is considered the problem of structuring indicators of the quality of information-computing systems, including transport. For each quality indicator is determined by the number of corresponding criteria. An algorithm for analysis of subscriber delays.
Keywords: quality, indicator of quality, quality criterion, computer information system of railway transport,subscriber delay
This article deals with the unification of the elements of wood as on the principle of similarity with the material counterpart. Also estimated the economic benefits of the technical parameters of Glulam. As a result of optimizing the size of these elements. Unification is held on the main criterion of similarity bearing members with the solution graphically. Resulting in optimal size sections are then calculated the opportunity cost of production.
Keywords: unification, glued wooden structures