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Wyszukujesz frazę "Toropov, A. A." wg kryterium: Autor


Wyświetlanie 1-11 z 11
Tytuł:
AlGaN Quantum Well Heterostructures for Mid-Ultraviolet Emitters with Improved Room Temperature Quantum Efficiency
Autorzy:
Shevchenko, E.
Toropov, A.
Nechaev, D.
Jmerik, V.
Shubina, T.
Ivanov, S.
Yagovkina, M.
Pozina, G.
Bergman, J.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1376069.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
78.55.Cr
71.35.-y
78.66.-w
Opis:
We report on optical studies of exciton localization and recombination kinetics in two single 2.2 nm thick $Al_{x}Ga_{1-x}N$/$Al_{x+0.1}Ga_{0.9-x}N$ quantum well structures (x=0.55 and 0.6) grown by plasma assisted molecular beam epitaxy on a c-sapphire substrate. Strong localization potential inherent for both the quantum well and barrier regions results in merging of the quantum well and barrier emission spectra into a single broad line centered at 285 nm (x=0.55) and 275 nm (x=0.6). Time-resolved photoluminescence measurements revealed surprising temperature stability of the photoluminescence decay time constant ( ≈ 400 ps) relevant to the recombination of the quantum well localized excitons. This observation implies nearly constant quantum efficiency of the quantum well emission in the whole range from 4.6 to 300 K.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1140-1142
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Breakdown of the Quantum Hall Effect
Autorzy:
Maude, D. K.
Rigal, L. B.
Desrat, W.
Potemski, M.
Portal, J. C.
Eaves, L.
Wasilewski, Z. R.
Toropov, A. I.
Hill, G.
Powiązania:
https://bibliotekanauki.pl/articles/2027467.pdf
Data publikacji:
2001-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Pm
74.25.Dw
Opis:
The breakdown of the dissipationless conductance in the integer and fractional quantum Hall effect regime is reviewed. The temperature dependence of the critical current and of the critical magnetic field at breakdown bears a striking resemblance to the phase diagram of the phenomenological two-fluid Gorter-Casimir model for superconductivity. In addition, a remarkably simple scaling law exists between different filling factors.
Źródło:
Acta Physica Polonica A; 2001, 100, 2; 213-226
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cd(Mg)Se Single Layers and CdSe/CdMgSe Heterostructures Grown by Molecular Beam Epitaxy on InAs(001) Substrates
Autorzy:
Kaygorodov, V. A.
Sorokin, V. S.
Sedova, I. V.
Nekrutkina, O. V.
Sorokin, S. V.
Shubina, T. V.
Toropov, A. A.
Ivanov, S. V.
Powiązania:
https://bibliotekanauki.pl/articles/2028799.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Hf
Opis:
We report on molecular beam epitaxy of CdSe/CdMgSe heterostructures on InAs(001) substrates and studies of their optical and structural properties. The CdMgSe energy gap versus composition dependence is determined. The zinc-blende MgSe band-gap energy and optical bowing parameter are estimated to be 4.05 eV and 0.2 eV, respectively. The CdSe quantum wells embedded into CdMgSe barriers demonstrate intense photoluminescence. Effective mass approximation calculations of electron-heavy hole optical transitions in CdSe quantum well are in a good agreement with the experimental data obtained.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 443-450
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CdSe Layers of Below Critical Thickness in ZnSe Matrix: Intrinsic Morphology and Defect Formation
Autorzy:
Sedova, I.
Shubina, T.
Sorokin, S.
Sitnikova, A.
Toropov, A.
Ivanov, S.
Willander, M.
Powiązania:
https://bibliotekanauki.pl/articles/1992185.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.45.+h
Opis:
Three main stages of the intrinsic morphology transformation of MBE grown CdSe fractional monolayers in ZnSe with increase in their nominal thickness w in the 0.1-3.0 monolayer range were found using both structural and optical characterization techniques. Emergence of the extended (15-30 nm) CdSe-enriched quantum-dot-like pseudomorphic islands at w>0.7 monolayer with the density increasing up to 2.5×10$\text{}^{10}$ cm$\text{}^{-2}$ at w=2.8 monolayer is clearly displayed in the optical properties of CdSe fractional monolayer nanostructures. The below critical thickness CdSe fractional monolayers having extremely high quantum efficiency can be very perspective as an active region of ZnSe-based blue-green lasers.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 519-525
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined (ZnSe/MgS)/ZnCdSe Bragg Reflectors Grown Using ZnS as a Sulphur Source
Autorzy:
Solnyshkov, D. D.
Sorokin, S. V.
Sedova, I. V.
Toropov, A. A.
Ivanov, S. V.
Powiązania:
https://bibliotekanauki.pl/articles/2044540.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.40.Fy
Opis:
We report on MBE growth and study of optical and structural properties of (ZnSe/MgS)/ZnCdSe distributed Bragg reflectors with λ=520 nm and R$\text{}_{max}$=97%. The samples were grown pseudomorphically on GaAs substrate using ZnS as a sulphur source. Scanning electron microscopy, X-ray diffraction, and optical measurements showed good optical and structural characteristics of the Bragg reflectors.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 873-877
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of numerical model of Lenze 530 Dc drive in Matlab
Autorzy:
Golodnyi, I.
Lawrinenko, Yu.
Toropov, A.
Powiązania:
https://bibliotekanauki.pl/articles/410698.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
transition process
semiconductor voltage converters
feedback
PI-controls
electromechanical characteristics
model
Opis:
This paper describes DC drive with thyristor voltage regulator Lenze 530 series. To investigate the transients of the drive system developed numerical model in MatLab is developed. Dual circuit structural diagram of “TCV-DC motor” system with negative feedback for the current and angular speed or current and armature voltage in model is realized. By introduction of current feedback, torque and current limit are achieved and with using of armature voltage or tacho automatic speed stabilization is obtained. At this model certain standard settings of cascade control system are made. The basis of the internal loop consist from PI-regulator with KP.C=2 and KI.C=100 gains, TCV and armature transfer functions, covered by armature current feedback. Current controller is configured at technical optimum. Second circuit can have armature voltage feedback; can be tuned at technical optimum and has a P-regulator with KP.S=36 gain. In same way it can have a speed negative feedback with the same tunings. A numerical model has restrictive blocks: to limit the maximum and minimum speed and maximum current. To demonstrate the obtained results virtual oscilloscopes were used. Also the electromechanical characteristics of the drive with armature voltage and current or speed and current feedbacks using XYGraph block are presented. At this paper the electromechanical characteristic of the real DC drive Lenze 530 series is presented too. According to research results at numerical model and physical investigation equipment graphs of instantaneous values of current and electromechanical characteristics are made. Analysis of graphs confirms the adequacy of the results obtained at the numerical model and the real drive system, which enables the use of the developed numerical model for the investigation of similar DC drives. DC drive model with thyristor voltage regulator Lenze 534 and results of investigations of electromechanical properties are presented.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2014, 3, 1; 41-47
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magneto-Optical Studies of Narrow Band-Gap Heterostructures with Type II Quantum Dots InSb in an InAs Matrix
Autorzy:
Mukhin, M.
Terent'ev, Ya.
Golub, L.
Nestoklon, M.
Meltser, B.
Semenov, A.
Solov'ev, V.
Sitnikova, A.
Toropov, A.
Ivanov, S.
Powiązania:
https://bibliotekanauki.pl/articles/1492858.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.-c
71.70.Ej
78.55.Cr
78.67.Hc
78.20.Ls
75.40.Mg
Opis:
Magneto-optical properties of type II heterostructures with InSb/InAs quantum dots has been studied at external magnetic field applied in the Faraday geometry. The emission polarization degree can be changed in the range from 100% σ-minus to 10% σ-plus due to excitation intensity and temperature variation. The detailed calculation of the band structure within a tight-binding approximation is presented. The simulation of the experimental data reveals that the oscillator strength of the optical transitions involving electrons with the spin oriented along and opposite to the magnetic field vector differs by approximately 1.8 times in the heterostructures under study.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 868-869
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Micro-photoluminescence studies of CdSe/ZnSe quantum dot structures grown under different conditions
Autorzy:
Rakhlin, M.
Sorokin, S.
Sedova, I.
Usikova, A.
Gronin, S.
Belyaev, K.
Ivanov, S.
Toropov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1156645.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.65.Hb
78.55.Et
81.07.Ta
Opis:
We report on comparative studies of CdSe/ZnSe quantum dot structures grown by molecular beam epitaxy either with or without predeposition of a sub-monolayer-thick CdTe layer (stressor). Also we consider the structure grown in a thermal activation mode. Emission properties of individual quantum dots are investigated by micro-photoluminescence spectroscopy using 500 nm apertures opened in a non-transparent gold mask. The density of emitting quantum dots and the spectral width of the single-dot emission lines are estimated.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-117-A-119
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Studies of Thermally Activated Vertical Hole Transport in ZnCdSe/ZnSSe Superlattice
Autorzy:
Lebedev, A.
Sorokin, S.
Toropov, A.
Shubina, T.
Il'inskaya, N.
Nekrutkina, O.
Ivanov, S.
Pozina, G.
Bergman, P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1991641.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Hf
78.45.+h
71.35.-y
78.47.+p
72.80.Ey
Opis:
Miniband transport in alternatively-strained ZnCdSe/ZnSSe short period superlattices is investigated using a structure with an enlarged quantum well. Temperature dependences of time-resolved and continuous wave photoluminescence have been measured, demonstrating an efficient temperature-induced vertical hole transport. A quantitative description is given for the carrier kinetics in these structures.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 421-426
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optically Pumped Low Threshold ZnSe Based Lasers with 2.8 ML CdSe Active Region
Autorzy:
Sorokin, S.
Toropov, A.
Shubina, T.
Lebedev, A.
Sedova, I.
Ivanov, S.
Waag, A.
Powiązania:
https://bibliotekanauki.pl/articles/1992195.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Hf
78.45.+h
Opis:
Room-temperature optically pumped (Zn,Mg)(S,Se)/(Zn,Cd)Se laser structures have been grown by molecular beam epitaxy. Using of alternatively-strained short-period superlattice waveguide results in low threshold power density values over the whole blue-green (470-520 nm) wavelength range. Incorporation of CdSe fractional monolayer active region provides more than fourfold further decrease in threshold with respect to quantum well laser structure. Optical and structural properties of laser structure with 2.8 monolayer CdSe are discussed in detail.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 539-544
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Optical Properties of Alternately-Strained $ZnS_{x}Se_{1-x}$/CdSe Superlattices with Effective Band-Gap 2.5-2.6 eV
Autorzy:
Evropeytsev, E.
Sorokin, S.
Gronin, S.
Sedova, I.
Klimko, G.
Sitnikova, A.
Baidakova, M.
Ivanov, S.
Toropov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1376074.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Pt
81.07.-b
78.55.-m
Opis:
We report on design and fabrication of alternately-strained $ZnS_xSe_{1-x}$/CdSe short period superlattices with the effective band-gap 2.52, 2.58, and 2.61 eV and the total thickness ≈300 nm. Transmission electron microscopy, X-ray diffraction, and photoluminescence measurements reveal negligibly small density of misfit dislocations in the superlattices. The investigation of carrier transport along the superlattice growth axis, performed by the photoluminescence measurements of a superlattice with one enlarged quantum well, confirms efficient Bloch-type transport at temperatures above ≈ 100 K. Such superlattices look promising for the applications as a material for the wide band-gap photoactive region of a multi-junction solar cell comprising both III-V and II-VI materials.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1156-1158
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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