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Wyszukujesz frazę "73.21.Fg" wg kryterium: Temat


Tytuł:
Dyakonov--Perel Spin Relaxation Suppressed by an Applied Magnetic Field
Autorzy:
Wilamowski, Z.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/2036865.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Rb
73.21.Fg
85.75.-d
Opis:
We observe a strong anisotropy of spin relaxation and a decrease in the spin relaxation rate with increasing electron mobility in contrast to predictions of the classical D'yakonov-Perel spin relaxation model. We show that for high electron mobility the cyclotron motion causes an additional modulation of spin-orbit coupling, leading to an effective suppression of the spin relaxation rate.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 671-674
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bychkov-Rashba Effect and g-Factor Tuning in Modulation Doped SiGe Quantum Wells
Autorzy:
Malissa, H.
Jantsch, W.
Mühlberger, M.
Schäffler, F.
Wilamowski, Z.
Draxler, M.
Bauer, P.
Powiązania:
https://bibliotekanauki.pl/articles/2038126.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
85.75.-d
Opis:
We investigate the spin resonance of electrons in one-sided modulation doped Si$\text{}_{1-x}$Ge$\text{}_{x}$ (x=0-10%)) quantum wells defined by Si$\text{}_{0.75}$Ge$\text{}_{0.25}$ barriers. In such structures, the Bychkov-Rashba effect induces an effective magnetic field in the quantum well layer which causes anisotropy of both the g-factor and the spin coherence time. Evaluation of the Rashba coefficient as a function of x yields a monotonic increase. For x=5% the shift in the resonance field exceeds the ESR linewidth already, demonstrating the possibility to use this effect for g-factor tuning to select individual spins in an ensemble.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 585-590
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrically Detected Magnetic Resonance
Autorzy:
Fedorych, O. M.
Wilamowski, Z.
Jantsch, W.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2038127.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Pk
72.25.Rb
73.21.Fg
Opis:
We compare the results of electrically detected magnetic resonance in a 2D electron gas in Si/SiGe quantum wells with transport and magnetic resonance measurements on ferromagnetic Ga$\text{}_{1-x}$Mn$\text{}_{x}$As. The results lead us to the conclusion that observation of electrically detected magnetic resonance is possible only in the case of a slow spin relaxation, where the microwave resonant absorption leads to a noticeable change of spin magnetization.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 591-598
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence of Highly Excited Nonpolar a-Plane GaN and AlGaN/GaN Multiple Quantum Wells
Autorzy:
Juršėnas, S.
Kuokštis, E.
Miasojedovas, S.
Kurilčik, G.
Žukauskas, A.
Chen, C. Q.
Yang, J. W.
Adivarahan, V.
Asif Khan, M.
Powiązania:
https://bibliotekanauki.pl/articles/2038100.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.21.Fg
72.20.Jv
78.47.+p
Opis:
Carrier recombination dynamics in polar and nonpolar GaN epilayers and GaN/AlGaN multiple quantum wells grown over sapphire substrates with various crystallographic orientation were studied under high photoexcitation by 20 ps laser pulses. The transient of luminescence featured a significant enhancement in nonradiative recombination of free carriers for nonpolar a-plane GaN epilayers compared to conventional c-plane samples. The epitaxial lateral overgrowth technique was demonstrated to significantly improve the quality of nonpolar a-plane films. This was proved by more than 40-fold increase in luminescence decay time (430 ps compared to ≤10 ps in the ordinary a-plane epilayer). Under high-excitation regime, a complete screening of built-in electric field by free carriers in multiple quantum wells grown on c-plane and r-plane sapphire substrates was achieved. Under such high excitation, luminescence efficiency and carrier lifetime of multiple quantum wells was shown to be determined by the substrate quality.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 567-573
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoluminescence of p-Doped Quantum Wells with Strong Spin Splitting
Autorzy:
Boukari, H.
Kossacki, P.
Bertolini, M.
Ferrand, D.
Cibert, J.
Tatarenko, S.
Gaj, J. A.
Deveaud, B.
Ciulin, V.
Powiązania:
https://bibliotekanauki.pl/articles/2038307.pdf
Data publikacji:
2004-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.-y
71.55.Gs
73.21.Fg
75.30.Hx
75.50.Pp
Opis:
Photoluminescence of p-type modulation doped (Cd,Mn)Te quantum wells is studied with carrier density up to 5×10$\text{}^{11}$ cm$\text{}^{-2}$ at various spin splittings. This splitting can be made larger than the characteristic energies of the system thanks to the giant Zeeman effect. At small spin splitting and regardless of the carrier density, the photoluminescence exhibits a single line, which corresponds to the charged exciton in the singlet state. Above a certain spin splitting, the charged exciton is destabilized in favor of the exciton at vanishing hole density, and in favor of a double line at higher carrier density. It is found here that the charged exciton destabilization energy hardly depends on the carrier density. The double line is found to be band-to-band like, with the same initial state - where the holes have the same spin orientation - and final states that differ by some excitation of the 2D hole gas. In addition, the spin splitting needed to fully polarize the hole gas is twice smaller than expected from the single particle image and gives a unique insight into many-body effects in the hole gas.
Źródło:
Acta Physica Polonica A; 2004, 106, 3; 299-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence of Highly Photoexcited GaN Epilayers and Heterostructures Grown on Different Sapphire Crystal Planes
Autorzy:
Juršėnas, S.
Miasojedovas, S.
Kurilčik, G.
Liuolia, V.
Žukauskas, A.
Chen, C. Q.
Yang, J. W.
Kuokštis, E.
Adivarahan, V.
Asif Khan, M.
Powiązania:
https://bibliotekanauki.pl/articles/2041736.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.21.Fg
72.20.Jv
78.47.+p
Opis:
GaN epilayers and AlGaN/GaN multiple quantum wells grown by metalorganic chemical vapor deposition on different crystal planes (c, a, and r) of the sapphire substrate were studied by excitation intensity dependent and time-resolved photoluminescence. In polar multiple quantum wells grown on a- and c-planes, a blueshift of the luminescence band with increasing the excitation energy was observed, indicating that screening of built-in field by free carriers takes place, whereas in nonpolar r-plane grown multiple quantum wells, the luminescence band maintained an almost constant peak position. Full screening of built-in field was achieved at the excitation densities higher than 0.3 mJ/cm$\text{}^{2}$. Under conditions of screened built-in electric field the structures were characterized by carrier lifetime. It was shown that nonpolar multiple quantum wells suffer from high density of nonradiative traps that can be due to substrate related threading dislocations.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 235-239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stimulated Emission from the MBE Grown Homoepitaxial InGaN Based Multiple Quantum Wells Structures
Autorzy:
Ivanov, V.
Godlewski, M.
Miasojedovas, S.
Juršėnas, S.
Kazlauskas, K.
Žukauskas, A.
Skierbiszewski, C.
Siekacz, M.
Leszczyński, M.
Perlin, P.
Suski, T.
Grzegory, I.
Powiązania:
https://bibliotekanauki.pl/articles/1179597.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.21.Fg
72.20.Jv
78.47.+p
Opis:
We report on photoluminescence characterization of InGaN based laser structures grown by homoepitaxial radio frequency plasma-assisted molecular beam epitaxy. Owing to Si doped barriers, the structures show a negligible impact of the built-in electric field, which was proved by excitation intensity dependent and quantum well width dependent luminescence experiments. Relatively low variation in band potential due to inhomogeneous distribution of In was quantitatively estimated from the photoluminescence temperature behavior using Monte Carlo simulation of in-plane carrier hopping and optically detected cyclotron resonance experiments. Efficient stimulated emission with a low threshold for optically pumped laser structures was observed.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 225-229
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of Exciton and Trion States in CdTe Quantum Well at High Magnetic Fields
Autorzy:
Andronikov, D.
Platonov, A.
Crooker, S.
Barrick, T.
Karczewski, G.
Kochereshko, V.
Powiązania:
https://bibliotekanauki.pl/articles/2043711.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Ji
73.21.Fg
78.55.Et
78.67.De
Opis:
Temperature dependent photoluminescence and reflectivity spectra of excitons, singlet and triplet states of trions were studied in CdTe-based quantum wells at high magnetic fields. Interesting features of the exciton and trion spectral lines with altering temperatures are explained by analyzing the thermal population and the kinetics of the exciton-electron-trion energetic system.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 653-660
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Radiation Induced Spin Photocurrents in Non-Magnetic Low Dimensional Structures
Autorzy:
Ganichev, S. D.
Prettl, W.
Powiązania:
https://bibliotekanauki.pl/articles/2043707.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
72.25.Fe
78.67.-n
73.21.Fg
Opis:
Spin photocurrents generated by homogeneous excitation with terahertz radiation in low dimensional structures are reviewed. Three microscopic mechanisms are responsible for the occurrence of an electric current linked to a uniform spin polarization in a quantum well, the circular photogalvanic effect, the spin-galvanic effect and the magneto-gyrotropic effect. These phenomena provide several methods to investigate various spin properties in low dimensional structures like details of band structure and spin relaxation time.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 581-608
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron-Hole Distribution and Exciton Condensed Phase Formation in Semiconductor Quantum Wells
Autorzy:
Chernyuk, A. A.
Sugakov, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/2046909.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Lk
73.21.Fg
Opis:
We study the development of ring luminescence of indirect excitons at macroscopical distances from the central excitation spot in quantum well structures. The Landau model for exciton condensation generalized for particles with finite lifetimes in conditions of inhomogeneous excitation is proposed. The transition between the fragmented and continuous rings and the temperature dependence of the effects are considered. The irradiation of the system by two spatially separated laser spots is simulated as well.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 169-174
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
III-Nitride Nanostructures for Infrared Optoelectronics
Autorzy:
Monroy, E.
Guillot, F.
Leconte, S.
Bellet-Amalric, E.
Nevou, L.
Doyennette, L.
Tchernycheva, M.
Julien, F. H.
Baumann, E.
Giorgetta, F.
Hofstetter, D.
Dang, Le Si
Powiązania:
https://bibliotekanauki.pl/articles/2046980.pdf
Data publikacji:
2006-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
78.67.De
85.60.Gz
85.35.Be
81.15.Hi
81.07.St
Opis:
Thanks to their large conduction band offset (~1.8 eV for the GaN/AlN system) and subpicosecond intersubband scattering rates, III-nitride heterostructures in the form of quantum wells or quantum dots are excellent candidates for high-speed unipolar devices operating at optical-fiber telecommunication wavelengths, and relying on the quantum confinement of electrons. In this work, we present the plasma-assisted molecular-beam epitaxial growth of quantum well infrared photodetector structures. The growth of Si-doped GaN/AlN multiple quantum well structures is optimized by controlling substrate temperature, metal excess and growth interruptions. Structural characterization confirms a reduction of the interface roughness to the monolayer scale. P-polarized intersubband absorption peaks covering the 1.33-1.91μm wavelength range are measured on samples with quantum well thickness varying from 1 to 2.5 nm. Complete intersubband photodetectors have been grown on conductive AlGaN claddings, the Al mole fraction of the cladding matching the average Al content of the active region. Photovoltage measurements reveal a narrow (~90 meV) detection peak at 1.39μm at room temperature.
Źródło:
Acta Physica Polonica A; 2006, 110, 3; 295-301
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Intersubband Scattering on the Magnetic Field Dependence of the Conductivity Tensor
Autorzy:
Siwiec-Matuszyk, J.
Baj, M.
Babiński, A.
Kasprzak, J.
Powiązania:
https://bibliotekanauki.pl/articles/2046999.pdf
Data publikacji:
2006-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.My
73.50.Jt
73.21.Fg
73.61.Ey
Opis:
In this paper we show that intersubband scattering can lead to apparent inconsistency of the experimental results obtained by means of classical and quantum transport measurements and this discrepancy is entirely connected with the usage of classical formulae to describe magnetic field dependence of a conductivity tensor. We prove that there is no contradiction in our observations and that the models describing quantum oscillations and magnetic-field dependence of the conductivity tensor, which are present in the literature, complement each other.
Źródło:
Acta Physica Polonica A; 2006, 110, 3; 337-344
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Semiconductor Nanostructures with nextnano$\text{}^{3}$
Autorzy:
Birner, S.
Hackenbuchner, S.
Sabathil, M.
Zandler, G.
Majewski, J. A.
Andlauer, T.
Zibold, T.
Morschl, R.
Trellakis, A.
Vogl, P.
Powiązania:
https://bibliotekanauki.pl/articles/2046896.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.43.Cd
73.21.Fg
73.61.Ey
77.65.Ly
85.30.Tv
73.40.Mr
Opis:
nextnano$\text{}^{3}$ is a simulation tool that aims at providing global insight into the basic physical properties of realistic three-dimensional mesoscopic semiconductor structures. It focuses on quantum mechanical properties such as the global electronic structure, optical properties, and the effects of electric and magnetic fields for virtually any geometry and combination of semiconducting materials. For the calculation of the carrier dynamics a drift-diffusion model based on a quantum-mechanically calculated density is employed. In this paper we present an overview of the capabilities of nextnano$\text{}^{3}$ and discuss some of the main equations that are implemented into the code. As examples, we first discuss the strain tensor components and the piezoelectric effect associated with a compressively strained InAs layer for different growth directions, secondly, we calculate self-consistently the quantum mechanical electron density of a Double Gate MOSFET, then we compare the intersubband transitions in a multi-quantum well structure that have been obtained with a single-band effective mass approach and with an 8-band k·p model, and finally, we calculate the energy spectrum of a structure in a uniform magnetic field.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 111-124
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shake-Up Processes in Photoluminescence of Two-Dimensional Holes in a High Magnetic Field
Autorzy:
Wójs, A.
Bryja, L.
Misiewicz, J.
Potemski, M.
Reuter, D.
Wieck, A.
Powiązania:
https://bibliotekanauki.pl/articles/2047047.pdf
Data publikacji:
2006-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Cc
71.35.Ji
73.21.Fg
Opis:
Recombination of excitons and positive trions is studied by two-beam photoluminescence of a two-dimensional hole gas in a high magnetic field. The singlet, dark-triplet and bright-triplet states of a free trion are resolved, and their binding energies are determined. Recombination of acceptor-bound trions is also detected, including a low-energy cyclotron replica, corresponding to a hole shake-up process. Identification of all these different transitions was possible by analysis of optical selection rules and the comparison of experimental spectra with realistic numerical calculations.
Źródło:
Acta Physica Polonica A; 2006, 110, 3; 429-435
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Skyrmions in a Hole Gas with Large Spin Gap and Strong Disorder
Autorzy:
Bryja, L.
Ryczko, K.
Wójs, A.
Misiewicz, J.
Potemski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2046907.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Mf
73.21.Fg
78.20.Ls
78.67.De
Opis:
In the photoluminescence excitation spectra of two-dimensional valence holes with large spin gap and strong disorder we find evidence for quantum Hall ferromagnetism and small skyrmions around the Landau level filling factorν=1. This interpretation is supported by numerical calculations.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 163-168
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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