共查询到20条相似文献,搜索用时 15 毫秒
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《Superlattices and Microstructures》1994,15(2):165
Experimental results on high electric field longitudinal transport in GaAs/AlAs and GaAs/Ga1-xAlxAs multiple quantum wells (MQW) are presented and compared with the prediction of a dielectric continuum model. We draw from our experiments the following four conclusions.(i) In GaAs/Ga1-xAlxAs systems the dominant energy and momentum relaxation mechanism is through scattering with GaAs -modes.(ii) However, in GaAs/AlAs systems the AlAs interface mode is dominant in relaxing the energy and momentum of the quantum well electrons.(iii) The hot electron momentum relaxation as obtained from the high-field drift velocity experiments is strongly affected by the production of hot phonons as expected from a model involving a non-drifting hot phonon distribution.(iv) The importance of the AlAs interface mode in GaAs/Ga1-xAlxAs MQW is not the result of the intrinsic scattering rate but related to its shorter lifetime, compared to GaAs modes. 相似文献
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In this paper, the third-harmonic generation (THG) in GaAs/Ga1 ? xAlxAs ridge quantum wires is studied in detail. An analytic expression for the THG is obtained using a compact density matrix approach and an iterative procedure. Numerical calculations are performed for the typical GaAs/Ga1 ? xAlxAs ridge quantum wire. The results show that the maximum THG over 10? 9? m2?/V2? can be obtained. Another important point is that the structural parameters have great influence on the THG in this system. 相似文献
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T. Nguyen-Quang J.-M. Jancu P. Voisin 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):352
A quantitative comparison between different model calculations of valence band states in GaAs/AlGaAs heterostructures is presented. We demonstrate that a 14-band k.p Hamiltonian using a completely new parameterization based on fits of the tight-binding band structure leads to energy dispersion relations in excellent agreement with experiment, whereas previous parameterizations result in significant deviations. The relevance of the present results to the calculation of spin-related phenomena is discussed. 相似文献
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Luminescence experiments have been performed on Multiple Quantum Wells structures with well thicknesses varying between 100 Å and 1000 Å. Varying the laser excitation density between 10mW cm?2 and 5 kW cm?2 allows to separate different bands related to hydrogenic impurities. The position of these bands are compared to the results of theoretical calculations on the binding energy of the impurity and on subband position. All our results are consistent with the calculations. 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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Summary The normal incidence reflectivity spectrum of excitons in GaAs/Ga1−x
Al
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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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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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Nonlinear optical rectification of GaAs/Ga1-xAlxAs quantum dots with Hulthén plus Hellmann confining potential
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Yi-Ming Duan 《中国物理 B》2023,32(1):17303-017303
We investigate the nonlinear optical rectification (NOR) of spherical quantum dots (QDs) under Hulthén plus Hellmann confining potential with the external tuning elements. Energy and wavefunction are determined by using the Nikiforov-Uvarov method. Expression for the NOR coefficient is derived by the density matrix theory. The results show that the applied external elements and internal parameters of this system have a strong influence on intraband nonlinear optical properties. It is hopeful that this tuning of the nonlinear optical properties of GaAs/Ga1-xAlxAs QDs can make a greater contribution to preparation of new functional optical devices. 相似文献
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用选择激发光荧光研究了分子束外延生长的GaAsSb/GaAs单量子阱的光学性质,第一次同时观察到空间直接(Ⅰ类)和间接(Ⅱ类)跃迁.它们表现出不同的特性:Ⅰ类跃迁具有局域化特性,其发光能量不随激发光能量而变;Ⅱ类发光的能量位置随激发功率的增大而蓝移,也随激发光能量的增加而蓝移,复合发光发生在位于异质结GaAs一侧的电子和GaAsSb中的空穴之间,实验结果可以很好地用电荷分离造成的能带弯曲模型来解释,这也是空间间接跃迁的典型特性.还用光荧光的激发强度关系和时间分辨光谱进一步论证了GaAsSb/GaAs能带排列的Ⅱ类特性,并通过简单计算得到了应变和非应变状态下GaAsSb/GaAs异质结的带阶系数. 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