共查询到19条相似文献,搜索用时 93 毫秒
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在多维球坐标体系中,我们对施主为束缚离子激子用二维方法求解薛定谔方程.研究表明,该方法对于半定量分析简便易行,并获得了一个重要的质量比σc=0.512. 相似文献
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在不同晶格温度和不同激发光强度下,测量了四元系GaInAsSb/GaAlAsSb单量子阱中自由激子的荧光光谱,导出了稳态光谱测量条件下自由激子荧光强度与激发光强度和晶格温度的一般性公式.计算结果表明,激子相对占有数引起的温度和密度效应会影响激子发光的强度关系.根据本文的简单模型,线性比例系数I/I0实际上综合地反映了量子阱中自由激子的荧光效率,而从激子荧光强度的Arrhenius图的最佳拟合中不仅可以得到激子的束缚能和激活能,而且还能估计出量子阱材料的本底浓度和散射时间常数.
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本文讨论了在ZnSe薄膜材料及ZnSe-ZnS多量子阱中宽阱材料和窄阱材料的激子弛豫过程和在窄阱材料中激子受激发射. 相似文献
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电场对量子阱中激子能级宽度的影响 总被引:8,自引:1,他引:7
付方正 《光谱学与光谱分析》2001,21(6):749-751
本文把固体中较大窨范围运动的粒子作为准经典粒子来描述。将已导出的能量测不准公式和激子的经典力学模型应用到电场下GaAs/GaAlAs量子阱中,激子能级宽度的计算结果与测量结果基本吻合,能较清楚、简单地解释纵向电场和横向电场下激子光吸收线宽的很大的差异。 相似文献
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近年来,半导体量子阱中激子的玻色一爱因斯坦凝聚研究取得了很大进展.实验上利用耦合量子阱间接激子中电子和空穴在空间上的分离,显著提高了激子的冷却速度和寿命,成功地把激子冷却到1K以下,观察到了激子的准凝聚状态,并且在强激光照射下,发现了随光照强度增强而增大的激子发光环和环上形成的有规则斑点图案,引起了广泛的兴趣和重视.理论研究表明,发光环的出现是电子和空穴在量子阱中的反常输运行为造成的,但环上形成规则斑点的物理机理目前尚不清楚.文章介绍了这方面的实验背景和形成激子环的物理图像,指出了理论研究中存在的问题,并对解决问题的方案进行了讨论. 相似文献
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A theory of the dephasing rate of quasi-2D free excitons due to acoustic phonon interaction at low exciton densities is presented. Both deformation potential and piezoelectric couplings are considered for the exciton–phonon interaction in quantum wells. Using the derived interaction Hamiltonian obtained recently by us, exciton linewidth and dephasing rate are calculated as a function of the exciton density, exciton temperature, exciton momentum and lattice temperature. 相似文献
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Oleg L. Berman Yurii E. Lozovik David W. Snoke Rob D. Coalson 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):268
The theory of what happens to a superfluid in a random field, known as the “dirty boson” problem, directly relates to a real experimental system presently under study by several groups, namely excitons in coupled semiconductor quantum wells. We consider the case of bosons in two dimensions in a random field, when the random field can be large compared to the repulsive exciton–exciton interaction energy, but is small compared to the exciton binding energy. The interaction between excitons is taken into account in the ladder approximation. The coherent potential approximation (CPA) allows us to derive the exciton Green's function for a wide range of the random field strength, and in the weak-scattering limit CPA results in the second-order Born approximation. For quasi-two-dimensional excitonic systems, the density of the superfluid component and the Kosterlitz–Thouless temperature of the superfluid phase transition are obtained, and are found to decrease as the random field increases. 相似文献
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Intersubband absorption with difference-frequency generation in GaAs asymmetric quantum wells 下载免费PDF全文
An asymmetric quantum well(AQW) is designed to emit terahertz(THz) waves by using difference frequency generation(DFG) with the structure of GaAs/Al 0.2 Ga 0.8 As/Al 0.5 Ga 0.5 As.The characteristics of absorption coefficients are analysed under the parabolic and non-parabolic energy-band conditions in detail.We find that the absorption coefficients vary with the two pump optical intensities,and they reach the maxima when the pump wavelengths are given as λ p1 = 9.70 μm and λ p2 = 10.64 μm,respectively.Compared with non-parabolic conditions,the total absorption coefficient under parabolic conditions shows a blue shift,which is due to the increase in the energy difference between the ground and excited states.By adjusting the two pump optical intensities,the wave vector phase-matching condition inside the AQW is satisfied. 相似文献
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A. Filoramo R. Ferreira Ph. Roussignol 《Physica E: Low-dimensional Systems and Nanostructures》1998,2(1-4)
We consider theoretically and experimentally the tunnel transfer of excitons in an asymmetric double quantum well structure. We interpret quantitatively the measured tunnel transfer time in terms of two intrinsic mechanisms for excitons: an inter-well Fano disintegration for excitons photocreated in an excited state and the inter-well emission of optical phonons. 相似文献
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建立了圆柱状量子点量子导线复合系统中激子满足的方程,用微扰论求出激子能量.以CdS/HgS/CdS/HgS/CdS圆柱状量子点量子导线复合系统为例,研究了系统中电子的概率分布和系统线度对激子能量的影响.结果表明:系统中电子、空穴以及激子的能量均随量子点高度h0的增大而减小,电子-空穴相互作用对基态激子能量的影响要大于激发态;电子沿径向方向的概率分布呈起伏状,在轴线和表面附近的概率趋于零,而在R/2附近概率最大;在量子点附近电子沿轴向方向的概率分布呈振荡特征
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量子点
量子导线
激子
能量 相似文献
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在有效质量近似下,考虑内建电场效应,采用变分法详细研究了受限于纤锌矿Mg_xZn_(1-x)O/ZnO/Mg_xZn_(1-x)O圆柱形应变量子点中离子受主束缚激子(A~-,X)的带间光跃迁吸收系数随量子点尺寸、Mg含量和离子受主杂质中心位置的变化情况,并和离子施主束缚激子(D~+,X)及自由激子进行了比较.结果表明:随着量子点尺寸的减小,(A~-,X)的光跃迁吸收强度增强,吸收曲线向高能方向移动,出现蓝移现象.随着Mg含量增加,(A~-,X)的光跃迁吸收曲线蓝移,且吸收强度减弱.随着离子受主杂质从量子点的左界面沿材料生长方向移至量子点的右界面,光跃迁吸收曲线向低能方向移动,出现红移现象.此外,与离子施主束缚激子(D~+,X)相比,随着沿材料生长方向掺入杂质位置的变化,光跃迁吸收曲线移动的方向相反.但不管是掺入离子受主杂质还是离子施主杂质,当离子杂质从量子点的左异质界面沿材料生长方向移至右异质界面时,光跃迁吸收峰的移动量大致相同. 相似文献
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We conducted a theoretical study on the electronic properties of a single-layer graphene asymmetric quantum well.Quantification of energy levels is limited by electron–hole conversion at the barrier interfaces and free-electron continuum.Electron–hole conversion at the barrier interfaces can be controlled by introducing an asymmetry between barriers and taking into account the effect of the interactions of the graphene sheet with the substrate.The interaction with the substrate induces an effective mass to carriers,allowing observation of Fabry–P′erot resonances under normal incidence and extinction of Klein tunneling.The asymmetry,between barriers creates a transmission gap between confined states and free-electron continuum,allowing the large graphene asymmetric quantum well to be exploited as a photo-detector operating at mid-and far-infrared frequency regimes. 相似文献
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We theoretically investigate the spin-orbit interaction in GaAs/AlxGa1 x As coupled quantum wells. We consider the contribution of the interface-related Rashba term as well as the linear and cubic Dresselhaus terms to the spin splitting. For the coupled quantum wells which bear an inherent structure inversion asymmetry, the same probability density distribution of electrons in the two step quantum wells results in a large spin splitting from the interface term. If the widths of the two step quantum wells are different, the electron probability density in the wider step quantum well is considerably higher than that in the narrower one, resulting in the decrease of the spin splitting from the interface term. The results also show that the spin splitting of the coupled quantum well is not significantly larger than that of a step quantum well. 相似文献