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514 results on '"Preobrazhenskii, V."'

7. Kinetics of structural changes on GaSb(001) singular and vicinal surfaces during the UHV annealing

Author

Vasev, A. V., Putyato, M. A., Preobrazhenskii, V. V., Bakarov, A. K., and Toropov, A. I.

Subjects
Condensed Matter - Materials Science
Abstract

The dynamics of processes of antimony desorption was investigated on the singular and vicinal GaSb(001) surface by RHEED method. The role of the terraces edges was determined during antimony evaporation in Langmuir desorption mode. It is shown that the structural transition (2x5) -> (1x3) is a complex of two transitions - order -> disorder and disorder -> order. The influence of the degree of surface miscut from the singular face on the dimension of the transition (2x5) -> DO was studied. The activation energies of structural transitions ex(2x5) -> (2x5), (2x5) -> DO and DO -> (1x3) on singular and vicinal faces GaSb(001) were determined., Comment: 2 pages, 2 figures

Published
2018
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8. Kinetics of (2x4) -> (3x1(6)) structural changes on GaAs(001) surfaces during the UHV annealing

Author

Vasev, A. V., Putyato, M. A., and Preobrazhenskii, V. V.

Subjects
Condensed Matter - Materials Science
Abstract

The peculiarities of superstructural transition (2x4) -> (3x1(6)) on the GaAs(001) surface were studied by the RHEED method in the conditions initiated by a sharp change of the arsenic flux. The specular beam intensities RHEED picture dependences on time were obtained during the transition. The measurement results were analyzed within the JMAK (Johnson - Melh - Avrami - Kolmogorov) kinetic model. It was established that the process of structural rearrangement proceeds in two stages and it is realized through the state of intermediate disordering, domains with different reconstructions being coexistent on the surface. The activation energies and phase transition velocities were determined for each of the stages. The procedure for precise determination of GaAs(001) surface temperature using the features of the a(2x4)->DO transition process kinetic was proposed. The results of this work allow us to broaden our understanding of the reconstruction transitions mechanisms. This information has a key (fundamental and applied) nature for the technologies of epitaxial growth of multilayer heterostructures, where the interface planarity and the sharpness of composition profile are of particular importance., Comment: 11 pages, 9 figures

Published
2018
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9. Some aspects of diffracted waves formation at RHEED on a reconstructed crystal face

Author

Vasev, A. V., Putyato, M. A., and Preobrazhenskii, V. V.

Subjects
Condensed Matter - Materials Science
Abstract

The evolution of RHEED reflexes intensity during reconstructed transitions characterizes (often implicitly) reconstructed surface state peculiarities. The approaches of a correct RHEED data interpretation, aimed at obtaining information about reconstructed transitions kinetics, are considered in the present work. In particular, the nature of RHEED reflexes formation, depending on such parameters as the average size of reconstructed domains and number of such domains per area unit, is analyzed within the kinematic approximation of the diffraction theory. This geometrical description is a convenient and effective (productive) way of analyzing reconstructed transitions mechanisms and parameters. The transformation of the functional dependence between the measured values (RHEED reflexes intensity picture) and the degree of surface coverage by reconstruction domains, at a change of these domains average size and distribution density, is shown. This work provides the community with a useful framework for such type of theoretical studies., Comment: 11 pages, 6 figures

Published
2017

10. Proximity-induced superconductivity within the InAs/GaSb edge conducting state

Author

Kononov, A., Kostarev, V. A., Semyagin, B. R., Preobrazhenskii, V. V., Putyato, M. A., Emelyanov, E. A., and Deviatov, E. V.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We experimentally investigate Andreev transport through the interface between an indium superconductor and the edge of the InAs/GaSb bilayer. To cover all possible regimes of InAs/GaSb spectrum, we study samples with 10 nm, 12 nm, and 14 nm thick InAs quantum wells. For the trivial case of a direct band insulator in 10~nm samples, differential resistance demonstrates standard Andreev reflection. For InAs/GaSb structures with band inversion (12~nm and 14 nm samples), we observe distinct low-energy structures, which we regard as direct evidence for the proximity-induced superconductivity within the current-carrying edge state. For 14~nm InAs well samples, we additionally observe mesoscopic-like resistance fluctuations, which are subjected to threshold suppression in low magnetic fields., Comment: final version

Published
2017
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11. Interlayer current near the edge of an InAs/GaSb double quantum well in proximity with a superconductor

Author

Kononov, A., Egorov, S. V., Titova, N., Semyagin, B. R., Preobrazhenskii, V. V., Putyato, M. A., Emelyanov, E. A., and Deviatov, E. V.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity
Abstract

We investigate charge transport through the junction between a niobium superconductor and the edge of a two-dimensional electron-hole bilayer, realized in an InAs/GaSb double quantum well. For the transparent interface with a superconductor, we demonstrate that the junction resistance is determined by the interlayer charge transfer near the interface. From an analysis of experimental $I-V$ curves we conclude that the proximity induced superconductivity efficiently couples electron and hole layers at low currents. The critical current demonstrates periodic dependence on the in-plane magnetic field, while it is monotonous for the field which is normal to the bilayer plane., Comment: 5 pages

Published
2016
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12. Specular Andreev reflection at the edge of an InAs/GaSb double quantum well with band inversion

Author

Kononov, A., Egorov, S. V., Kostarev, V. A., Semyagin, B. R., Preobrazhenskii, V. V., Putyato, M. A., Emelyanov, E. A., and Deviatov, E. V.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity
Abstract

We experimentally investigate transport through the side junction between a niobium superconductor and the mesa edge of a two-dimensional system, realized in an InAs/GaSb double quantum well with band inversion. We demonstrate, that different transport regimes can be achieved by variation of the mesa step. We observe anomalous behavior of Andreev reflection within a finite low-bias interval, which is invariant for both transport regimes. We connect this behavior with the transition from retro- (at low biases) to specular (at high ones) Andreev reflection channels in an InAs/GaSb double quantum well with band inversion., Comment: As accepted to JETP Letters, vol. 104, issue 1

Published
2016
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14. Optical Gates Based on Semiconductor Quantum Wells A\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${}_{\mathbf{3}}$$\end{document} \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${}_{\mathbf{5}}$$\end{document}B\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${}_{\mathbf{3}}$$\end{document} \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${}_{\mathbf{5}}$$\end{document}

Author

Rubtsova, N. N., Kovalev, A. A., Ledovskikh, D. V., Preobrazhenskii, V. V., Putyato, M. A., and Semyagin, B. R.

Published
2021
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20. Biomodification of Collagen-Containing By-Products by Enzymatic Hydrolysis

Author

Giro T., Zubov S., Yashin A., Giro A., and Preobrazhenskii V.

Subjects
collagen-containing raw materials, enzyme preparations, biotransformation, whey, functional products, Food processing and manufacture, TP368-456
Abstract

Low-value by-products can be processed using biotechnological methods, which seems to be the optimal solution for the problem of rational use of secondary raw materials. The authors introduce a method of biotransformation using whey and enzyme preparation of proteolytic action with subsequent massaging. The method neutralizes the specific smell, reduces the time of heat treatment, increases hydrophilicity, and reduces the mechanical strength of mutton rumen tissue. The experiment proved that the enzymatic effect on the connective tissue of the mutton rumen contributes to the destruction of disulfide and hydrogen bonds of the triple helix of the collagen macromolecule. It significantly reduces the mechanical strength and hydrothermal stability of collagen, which, in its turn, reduces the heat treatment time while increasing the functional and technological properties. The research revealed an increase in collagen digestibility. After 4 hours of fermentation, it was 4.5%, after 6 hours – 5.9%, and after 8 hours – 5.9%. Hence, the optimal period of fermentation was determined as 6 hours, since between 6 and 8 hours the main physical and chemical parameters improved insignificantly. The experiment in the cutting pressure of the raw lamb rumen tissue demonstrated softening of the structure as a result of the effect of the acidic medium on the collagen structure. An excess positive charge formed due to the suppression of dissociation of carboxyl groups of side chains. The loosening of the collagen structure occurred due to the expansion of fibrils in the polar areas, which can be attributed to the repulsion between similarly charged groups. As a result, the brine penetrated into the expanded area and caused swelling. The use of whey and fermentation contributed to an additional increase in moisture-binding and moisture-holding capacity. It loosened the structure of proteins and, thus, increased the degree of penetration and the immobilized moisture in the rumen. As a result, its mass increased by 10–20%, and the heat loss reduced. The composition of the brine contributed to the swelling, increased the diameter of the collagen fibers, and enlarged the surface of interaction in during massaging. Moisture was allowed to enter freely, which increased the water binding capacity by 22.2 ± 0.31%. The increase in the water binding capacity could be explained by the modification of collagen and its destructive changes. The changes occurred due to the additional interaction of whey molecules with the protein and the formation of new intermolecular bonds. Fermentation, combined with the massaging of the tripe, contributed to the development of lactic microflora and hydrolytic decomposition of protein components, thereby reducing the heat treatment process. Such changes are associated not only with the processes of protein hydrolysis under enzyme preparation, but also with the complex activity of lactic acid bacteria, as well as endo- and exoenzymes that hydrolyze proteins. The changes can also be attributed to the fact that low-molecular protein substances can assimilate and contribute to bacterial growth. In addition, lactic acid reduces the pH of the medium, thus activating the enzymatic properties. The proposed method of biotransformation of collagen-containing raw materials makes it possible to create environmentally friendly and low-waste technologies.

Published
2019
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29. Kinetics of exciton photoluminescence in type-II semiconductor superlattices

Author

Braginsky, L. S., Zaharov, M. Yu., Gilinsky, A. M., Preobrazhenskii, V. V., Putyato, M. A., and Zhuravlev, K. S.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation between the exciton recombination at the plane interface and at the roughness. Expressions that relate the parameters of the luminescence kinetics with statistical characteristics of the rough interface are obtained. The mean height and length of roughnesses in GaAs/AlAs superlattices are estimated from the experimental data., Comment: 3 PostScript figures

Published
2000
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34. Structure and Optical Properties of a Composite AsSb–Al0.6Ga0.4As0.97Sb0.03 Metamaterial.

Author

Snigirev, L. A., Ushanov, V. I., Ivanov, A. A., Bert, N. A., Kirilenko, D. A., Yagovkina, M. A., Preobrazhenskii, V. V., Putyato, M. A., Semyagin, B. P., Kasatkin, I. A., and Chaldyshev, V. V.

Subjects
OPTICAL properties, LIGHT absorption, EPITAXIAL layers, MOLECULAR beam epitaxy, ANTIMONY, EPITAXY
Abstract

epitaxial layers of AlxGa1–xAs1–y Sby with an aluminum content x ~ 60% and antimony content y ~ 3% were successfully grown by molecular-beam epitaxy at low temperature. A developed system of AsSb nanoinclusions was formed in the semiconductor matrix by subsequent annealing. The extended transparency window of the obtained metamaterial allows us to document the absorption of light near the interband absorption edge of the AlxGa1–xAs1–ySby semiconductor matrix. Parameters of the observed extinction band allow us to attribute the optical absorption to the plasmon resonance in the system of AsSb nanoinclusions. [ABSTRACT FROM AUTHOR]

Published
2023
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41. Growth of GaAs1–xBix Layers by Molecular-Beam Epitaxy.

Author

Semyagin, B. R., Kolesnikov, A. V., Putyato, M. A., Preobrazhenskii, V. V., Popova, T. B., Ushanov, V. I., and Chaldyshev, V. V.

Subjects
EPITAXY, EPITAXIAL layers, SOLID solutions, BISMUTH, OPTICAL properties
Abstract

by molecular-beam epitaxy we have grown epitaxial layers of GaAs1–xBix solid solutions with a bismuth content of 0 < x < 0.02. Structural and optical properties of the layers were investigated. We determine the influence of the bismuth flux and substrate temperature on the bismuth incorporation into the growing layers. [ABSTRACT FROM AUTHOR]

Published
2023
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44. Arrays of Quasi-One-Dimensional GaAs Nanocrystals Grown on the Oxidized Surface of the Si/GaAs(001) Heterostructure: Effect of the Si Epitaxial Layer on the Array Structure

Author

null Preobrazhenskii V. V., null Putyato M. A., null Vasev A. V., null Semyagin B. R., null Gavrilova T. A., null Spirina A. A., null Nastovjak A. G., null Petrushkov M. O., null Del’ T. A., and null Emelyanov E. A.

Abstract

Structures with arrays of planar and tilted quasi-one-dimensional GaAs nanocrystals have been grown on GaAs(001) substrates. An epitaxial silicon layer oxidized in air was used as a passivation coating. The amount of silicon deposited varied from structure to structure and was equivalent to 1, 2, 4, and 6 atomic layers. It has been found that in the case of a passivation layer based on silicon with a thickness of 1 atomic layer, an array of planar nanocrystals is formed, and in other cases, inclined quasi-one-dimensional nanocrystals. Nanocrystals are surrounded by crystallites, the shape, size, orientation, and distribution density of which change with the amount of silicon. The lowest density of crystallites was achieved with a silicon layer 6 atomic layers thick. Keywords: molecular-beam epitaxial, GaAs, Si, quasi-one-dimensional nanocrystals, vapour-liquid-crystal.

Published
2023
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