共查询到20条相似文献,搜索用时 15 毫秒
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Syperek M Yakovlev DR Greilich A Misiewicz J Bayer M Reuter D Wieck AD 《Physical review letters》2007,99(18):187401
Carrier spin coherence in a p-doped GaAs/(Al,Ga)As quantum well with a diluted hole gas is studied by picosecond pump-probe Kerr rotation. For resonant optical excitation of the positively charged exciton the spin precession shows two types of oscillations: Electron spin beats decaying with the charged exciton radiative lifetime of 50 ps, and long-lived hole spin beats with dephasing times up to 650 ps, which decrease with increasing temperature, underlining the importance of hole localization. The mechanism of hole spin coherence generation is discussed. 相似文献
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《Solid State Communications》1986,60(7):557-561
We have studied the effect of superlattice structure on the 1s to 2p+ transition energy of shallow donors. In a strong magnetic field along the growth direction the transition is inhomogeneously broadened with absorption features that can be correlated with the position of the donor with respect to the barriers and wells. The results compare well with recent theory of donors in superlattices and are potentially important for the determination of donor distributions in superlattices. 相似文献
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N. N. Ledentsov R. Nötzel P. S. Kop'ev K. Ploog 《Applied Physics A: Materials Science & Processing》1992,55(6):533-536
Hot exciton relaxation is observed in GaAs/Al
x
Ga1–x
As multiple quantum wells. The photolumnescence excitation spectra of the localized exciton emission at low temperatures and excitation densities are composed of narrow equidistant peaks exactly separated by the GaAs LO-phonon energy (36 meV). The relaxation mechanism via LO-phonons is found to be important for localized excitons in multiple quantum wells with GaAs layer thicknesses of about 50 Å, where pronounced alloy fluctuations in the barriers provide a strong additional lateral potential which suppresses the dissociation of hot excitons. 相似文献
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Il Nuovo Cimento D - The influence of biexciton formation on the four-wave-mixing response of multiple quantum wells having a strong inhomogeneous broadening of the exciton transitions has been... 相似文献
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Summary The normal incidence reflectivity spectrum of excitons in GaAs/Ga1−x
Al
x
As multiple quantum wells is calculated within the local response approximation. It is shown that the reflectivity lineshape
strongly depends on the sample geometry. Using realistic parameters of a multiple quantum well structure, we obtain an excellent
fit of the experimental reflectivity curve, thus giving exciton energies, oscillator strengths and exciton broadening parameters.
Riassunto Lo spettro di riflettività ad incidenza normale degli eccitoni nei pozzi quantistici multipli di GaAs/Ga1−x Al x As è calcolato nell’ambito dell’approssimazione locale. Si mostra con la forma della linea di riflettività dipende in gran misura dalla forma geometrica del campione. Usando parametri realistici di una struttura a pozzi quantistici multipli, si ottiene un’ottima approssimazione della curva di riflettività sperimentale, che fornisce così energie eccitoniche, forze dell’oscillatore e parameri di ampliamento eccitonico.
Резюме В рамках приближения линейного отклика вычисляется спекрт отражательной способности экситонов при нормальном падении для множественных квантовых ям в GaAs/Ga1−x Al x As. Показывается, что форма линии отражательной способности сильно зависит от геометрии образца. Используя реалистические параметры структуры множественных квантовых ям, мы получаем хорошее соответствие с экспериментальной кривой для отражательной способности. Получаются энергии экситонов, силы осцилляторов и парам⪟тры экситонного уширения.相似文献
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R. V. Kuz’min V. V. Krivolapchuk E. S. Moskalenko M. M. Mezdrogina 《Physics of the Solid State》2010,52(6):1260-1266
Fluctuations in time of the intensity of indirect exciton photoluminescence in GaAs/Al0.33Ga0.67As double quantum wells have been studied. An analysis of the behavior of the intensity fluctuations under variation in external control parameters, such as the temperature and the voltage applied perpendicular to the structure, has revealed that they directly reflect the manifestation of Bose condensation. It has been demonstrated that the current flowing perpendicular to the structure also undergoes pronounced fluctuations simultaneously with those of the intensity. A study of possible reasons that could account for the onset of such fluctuations suggests the need for taking into account tunneling transitions in the exciton Bose condensate system. 相似文献
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G. Cassabois S. Meccherini Ph. Roussignol F. Bogani M. Gurioli M. Colocci R. Planel V. Thierry-Mieg 《Physica E: Low-dimensional Systems and Nanostructures》1998,2(1-4)
The intermediate dimensionality regime is studied on a set of shallow GaAs/Ga
Al
As single quantum wells. Such heterostructures exhibit 2D strong excitonic electroabsorption together with near 3D fast transport properties. We report dephasing time measurements
of the heavy-hole exciton and we show that the acoustic phonon contribution decreases with
to a value in good agreement with theoretical predictions for GaAs bulk. 相似文献
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I. M. Catalano A. Cingolani M. Lepore R. Cingolani K. Ploog 《Il Nuovo Cimento D》1990,12(10):1465-1474
Summary The two-photon absorption spectra of GaAs/AlGaAs multiple quantum well and superlattice structures have been experimentally
investigated by means of the nonlinear luminescence technique in different polarization configurations. A strong excitonic
effect overlapping the interband two-photon spectrum has been found and the selection rules for the excitonic transitions
have shown to greatly change for different polarizations. The comparison of linear and nonlinear absorption measurements provides
important information on the excited states of excitons in multiple quantum wells.
Work partially supported by M.P.I. 相似文献
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The internal transitions and absorption spectra of confined magnetoexcitons in GaAs/Ga0.TA10.aAs quan- tum wells have been theoretically investigated under magnetic fields along the growth direction of the semiconductor heterostructure. The magnetoexciton states are obtained within the effective-mass ap- proximation by using a variational procedure. The trial exciton-envelope wavefunctions are described as hydrogeniclike polynomial functions. The internal transition energies are investigated by studying the allowed magnetoexcitonic transitions using terahertz radiation circularly polarized in the plane of the quantum well. The intraexcitonic magnetoabsorption to 2p^± like magnetoexciton states as functions of the coefficients are obtained for transitions from 1s-like applied magnetic field. 相似文献
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