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Мигас, Дмитрий Борисович

Организационные подразделения

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Институт нанотехнологий в электронике, спинтронике и фотонике

Институт ИНТЭЛ занимается научной деятельностью и подготовкой специалистов в области исследования физических принципов, проектирования и разработки технологий создания компонентной базы электроники гражданского и специального назначения, а также построения современных приборов на её основе. Наша основная цель – это создание и развитие научно-образовательного центра мирового уровня в области наноструктурных материалов и устройств электроники, спинтроники, фотоники, а также создание эффективной инновационной среды в области СВЧ-электронной и радиационно-стойкой компонентной базы, источников ТГц излучения, ионно-кластерных технологий материалов.

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Мигас

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Дмитрий Борисович

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Теперь показываю 1 - 10 из 26

Только метаданные
Effects of lattice parameter manipulations on electronic and optical properties of BaSi2
(2019) Shohonov, D. A.; Filonov, A. B.; Takabe, R.; Suemasu, T.; Migas, D. B.; Borisenko, V. E.; Мигас, Дмитрий Борисович
© 2019 Elsevier B.V.We present comprehensive experimental and theoretical investigation on a band-gap engineering and modification in optical properties of BaSi2 – a new and very promising material for solar cell fabrication. BaSi2 thin films have been synthesized by molecular beam epitaxy with various deposition rates of Si and Ba. Changes in their band gaps and shifts in absorption edges with respect to alteration in the a lattice parameter have been investigated by optical measurements. It is possible to shrink a by about 0.003 nm (or 0.3%), while the other lattice parameters are locked by the epitaxial relationship with a Si(111) substrate, that leads to the gap reduction from 1.28 eV to 1.20 eV. By means of ab initio calculations we explore a possibility to manipulate band-gap values in BaSi2 along with the corresponding shift in the absorption edge by changing its a, b and c lattice parameters. It is revealed that an increase in any of the lattice parameters provides band-gap enlargement while the opposite trend is observed when decreasing the lattice parameters. Numerically uniaxial lattice strain of 3% can provide variations in the band gap up to 0.1 eV. We also discuss possible reasons for a variation and applicability of the band-gap engineering in BaSi2 by strain.
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Marked enhancement of the photoresponsivity and minority-carrier lifetime of BaS i2 passivated with atomic hydrogen
(2019) Xu, Z.; Shohonov, D. A.; Filonov, A. B.; Gotoh, K.; Migas, D. B.; Borisenko, V. E.; Мигас, Дмитрий Борисович
© 2019 American Physical Society.Passivation of barium disilicide (BaSi2) films is very important for their use in solar cell applications. In this paper, we demonstrated the effect of hydrogen (H) passivation on both the photoresponsivity and minority-carrier lifetime of BaSi2 epitaxial films grown by molecular beam epitaxy. First, we examined the growth conditions of a 3-nm-thick hydrogenated amorphous silicon (a-Si) capping layer formed on a 500-nm-thick BaSi2 film and found that an H supply duration (ta-Si:H) of 15 min at a substrate temperature of 180 °C sizably enhanced the photoresponsivity of the BaSi2 film. We next supplied atomic H to BaSi2 epitaxial films at 580 °C and changed supply duration (tBaSi;H) in the range of 1-30 min, followed by capping with an a-Si layer. The photoresponsivity of the films changed considerably depending on tBaSi;H and reached a maximum of 2.5 A/W at a wavelength of 800 nm for the sample passivated for tBaSi;H=15 min under a bias voltage of 0.3 V applied to the front-surface indium-tin-oxide electrode with respect to the back-surface aluminum electrode. This photoresponsivity is approximately one order of magnitude higher than the highest value previously reported for BaSi2. Microwave photoconductivity decay measurements revealed that the minority-carrier lifetime of the BaSi2 film with the highest photoresponsivity was 14 μs, equivalent to its bulk carrier lifetime ever reported. We performed theoretical analyses based on a rate equation including several recombination mechanisms and reproduced the experimentally obtained decay curves. We also calculated the total density of states of BaSi2 by ab initio studies when one Si vacancy existed in a unit cell and one, two, and three H atoms occupied Si vacancy or interstitial sites. A Si vacancy caused a localized state with two energy bands to appear close to the middle of the band gap. In certain cases, H passivation of the Si dangling bonds can markedly decrease trap concentration. From both experimental and theoretical viewpoints, we conclude that an atomic H supply is beneficial for BaSi2 solar cells.
Только метаданные
Stability of 2D Alkaline-Earth Metal Silicides, Germanides and Stannides
(2019) Alekseev, A. Yu.; Chernykh, A. G.; Filonov, A. B.; Skorodumova, N. V.; Migas, D. B.; Мигас, Дмитрий Борисович
By means of ab initio calculations, we have estimated stability of 2D Me2X (Me = Mg, Ca, Sr, Ba and X = Si, Ge, Sn) in the T and Td phases, which are similar to the ones of 2D transition metal chalcogenides, in addition to their phonon spectra. The T phase is found to be more stable for 2D Ca2X, Sr2X and Ba2X, whereas the Td phase is predicted to be the ground state for 2D Mg2X. We have also discussed that imaginary frequencies in the calculated phonon spectra of 2D Me2X, which appeared in the vicinity of the Gamma point, were not necessarily associated with the dynamic instability.
Только метаданные
Mechanisms of carrier lifetime enhancement and conductivity-type switching on hydrogen-incorporated arsenic-doped BaSi2
(2021) Aonuki, S.; Xu, Z.; Yamashita, Y.; Gotoh, K.; Migas, D. B.; Мигас, Дмитрий Борисович
© 2021 Elsevier B.V.A comparative experimental and theoretical study of the role of H incorporation in As-doped BaSi2 films has been carried out based on the experimental results that an optimal time of H treatment for the increase in photoresponsivity and carrier lifetime was in the range of 1 – 20 min. Adequate theoretical representation of the decay curves in the framework of the model for non-radiative processes accounted for various trap-related recombination mechanisms to estimate the trap concentration to be in the range of 1.9 × 1013 to 1.7 × 1014 cm−3. Additionally, the extended theoretical ab initio quantum-chemical simulation of the electronic structure of the studied systems was performed. It was revealed that interstitial As atoms can mostly provide trap states in the gap while H atoms neutralize such traps. The experimentally observed unexpected switching in conductivity from n-type to p-type and vice versa in As-doped BaSi2 with H incorporation was explained to specific configurations of point defects (an As impurity with a H atom in different positions and various interatomic As-H distances) which affect the position of states in the gap.
Только метаданные
Effects of bipolarons on oxidation states, and the electronic and optical properties of W18O49
(2021) Migas, D. B.; Filonov, A. B.; Skorodumova, N. V.; Мигас, Дмитрий Борисович
W18O49 has been studied by means of ab initio techniques in the framework of the density functional theory using the onsite Hubbard-U correction applied to the W-d states as well as using the hybrid potential. The existence of bipolarons is found to be an intrinsic feature of this oxide resulting in the presence of different oxidation states of W atoms (W6+ and W5+) and in the co-existence of localized and delocalized electrons. We also discuss possible switching from the W6+ to W5+ and from the W5+ to W4+ oxidation states in the presence of an O vacancy. It appears that O vacancy formation does not cause any additional charge localization at W sites but solely contributes to delocalized electrons. The calculated absorption and reflection coefficients manifest a transparency window in the visible region. At the same time, sizable absorption, occurring due to the presence of free carriers, is detected in the far and mid infrared regions. Additionally, in the near infrared region we confirm and explain an experimentally observed shielding effect originating from transitions involving the localized bipolaronic states.
Только метаданные
Crystal Structure, Optical Properties, and Characteristics of the Band Gap of Ca2Si Semiconductor Films on an Al2O3(0001) Substrate
(2022) Galkin, N. G.; Galkin, K. N.; Chernev, I. M.; Kropachev, O. V.; Goroshko, D. L.; Subbotin, E. Y.; Migas, D. B.; Мигас, Дмитрий Борисович
Только метаданные
The Nature of Ferromagnetism in a System of Self-Ordered α-FeSi2 Nanorods on a Si(111)-4° Vicinal Surface: Experiment and Theory
(2022) Galkin, N. G.; Goroshko, D. L.; Tkachenko, I. A.; Samardak, A. Y.; Galkin, K. N.; Subbotin, E. Y.; Dotsenko, S. A.; Migas, D. B.; Gutakovskii, A. K.; Мигас, Дмитрий Борисович
Только метаданные
Recent Progress Toward Realization of High-Efficiency BaSi2 Solar Cells: Thin-Film Deposition Techniques and Passivation of Defects
(2022) Suemasu, T.; Migas, D. B.; Мигас, Дмитрий Борисович
© 2021 Wiley-VCH GmbHSafe, stable, and earth-abundant materials for solar cell applications are of particular importance to realize a decarbonized society. Semiconducting barium disilicide (BaSi2), which is composed of nontoxic and earth-abundant elements, is an emerging material to meet this requirement. BaSi2 has a bandgap of 1.3 eV that is suitable for single-junction solar cells, a large absorption coefficient exceeding that of chalcopyrite, and inactive grain boundaries. This review is started by describing the recent progress of BaSi2 thin-film deposition techniques using radio-frequency sputtering and discuss the high photoresponsivity of BaSi2 thin films. Special attention is paid to passivation of the defects in BaSi2 films by hydrogen or carbon doping. Ab initio studies based on density-functional theory are then used to calculate the positions of the localized defective states and the Fermi level to discuss the experimentally obtained passivation effects. Finally, the issues that need to be resolved toward realization of high-efficiency BaSi2 solar cells are addressed.
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New monoclinic ground state of FeSi
(2024) Galkin, N. G.; Migas, D. B.; Medvedeva, N. V.; Filonov, A. B.; Мигас, Дмитрий Борисович
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Effects of Si/Ge superlattice structure with intermixed interfaces on phonon thermal conductivity
(2025) Khamets, A. L.; Safronov, I. V.; Filonov, A. B.; Migas, D. B.; Мигас, Дмитрий Борисович