SO和LO声子对GaAs-Ga1-xAlxAs量子阱中激子束缚能的影响

本文考虑了电—声子耦合作用,应用么正变换方法计算了GaAs-Ga1-xAlxAs量子阱中的激子束缚能;得到了激子束缚能随阱宽变化的曲线。当考虑激子声子相互作用后,激子相对于电子极化子和空穴极化子的第一子带底的束缚能小于相应的裸激子的束缚能量。     

抛物量子阱中束缚极化子的极化势和结合能

利用改进的Lee-Low-Pines(LLP)方法,用变分法计算了无限深抛物量子阱中同时考虑与体纵光学声子和界面纵光学声子相互作用的束缚极化子的极化势和结合能.数值计算得出:阱宽较大时极化势很小,阱宽较小时极化势较大,所以对于较窄的抛物阱必须考虑极化势.对于给定阱宽的抛物阱,随着远离阱中心极化势迅速减小,当到达阱的界面附近极化势又开始增大.阱宽较小时,束缚极化子的结合能随着阱宽L的增大而急剧减小;阱宽较大时,结合能减小的非常缓慢,最后接近体材料中的三维值.     

磁场对量子阱中弱耦合束缚极化子性质的影响

采用线性组合算符及幺正变换方法研究了磁场对量子阱中弱耦合束缚极化子的性质的影响。导出了量子阱中束缚极化子的基态能量与振动频率、库仑束缚势、磁场和阱宽之间的变化关系。同时也讨论了振动频率与库仑束缚势、磁场之间的变化关系。通过数值计算结果表明:量子阱中束缚极化子的基态能量因振动频率、库仑束缚势、磁场和阱宽的不同而不同,它随振动频率和磁场的增加而增大,随库仑束缚势和阱宽的增大而减小。量子阱中束缚磁极化子的基态能量与振动频率无关,随库仑束缚势和阱宽的增大而减小,随磁场的增大而增大。     

量子阱中强耦合束缚极化子的温度效应

采用线性组合算符与变分相结合的方法讨论了无限深量子阱中强耦合束缚极化子的温度效应.给出了无限深量子阱中束缚极化子的基态能量和振动频率随温度和阱宽的变化关系.对RbCl晶体进行了数值计算,结果表明：当温度升高时,量子阱中强耦合束缚极化子的振动频率增大,基态能量的绝对值增大;并且基态能量的绝对值随阱宽增大而增大.     

量子阱中强耦合束缚极化子的温度效应

采用线性组合算符与变分相结合的方法讨论了无限深量子阱中强耦合束缚极化子的温度效应.给出了无限深量子阱中束缚极化子的基态能量和振动频率随温度和阱宽的变化关系.对RbCl晶体进行了数值计算,结果表明:当温度升高时,量子阱中强耦合束缚极化子的振动频率增大,基态能量的绝对值增大;并且基态能量的绝对值随阱宽增大而增大.     

抛物量子阱中束缚极化子的温度效应

理论研究了抛物量子阱中强耦合束缚极化子的温度效应,采用线性组合算符和幺正变换相结合的方法得到了极化子基态能量和基态结合能的表达式.极化子基态能量和基态结合能分别是振动频率、电子-声子耦合强度、库仑束缚势强度、阱宽以及阱深的函数.在有限温度下,电子-声子系统将不再完全处于基态,晶格振动不但激发实声子,同时也使电子受到激发...     

光学材料 光电功能材料

O471.12006010718抛物量子阱中束缚极化子的极化势和结合能=Polariza-tion potential and binding energy of a bound polaron in aparabolic quantum well[刊,中]/元丽华(兰州理工大学理学院.甘肃,兰州(730050)),王旭…∥发光学报.—2005,26(6).—709-713利用改进的Lee-Low-Pines(LLP)方法,用变分法计算了无限深抛物量子阱中同时考虑与体纵光学声子和界面纵光学声子相互作用的束缚极化子的极化势和结合能。数值计算得出,阱宽较大时极化势很小,阱宽较小时极化势较大,所以对于较窄的抛物阱必须考虑极化势。图4参14(严寒)O471.12006010719…     

Cu-O平面量子阱结构中的大双极化子

在铜氧化物超导体中,空穴在内的运动往往归结为量子阱中的极化子问题.我们首次推广和发展了适用于全耦合空间的非微扰理论方法,对Cu-O平面内的磁极化子问题进行了深入地研究和讨论.通过数值计算,我们发现随着磁场的加强或有效量子阱尺度的减小,Cu-O平面内极化子的束缚能显著增大.同时,磁极化子效应还与Cu-O面的对称性紧密相关.     

纤锌矿In_(0.19)Ga_(0.81)N/GaN量子阱中光学声子和内建电场对束缚极化子结合能的影响

用改进的Lee-Low-Pines变分方法研究纤锌矿In0.19Ga0.81N/GaN量子阱结构中束缚极化子能量和结合能等问题,给出基态结合能、不同支长波光学声子对能量和结合能的贡献随阱宽和杂质中心位置变化的数值结果.在数值计算中包括了该体系中声子频率的各向异性和内建电场对能量和结合能的影响、以及电子和杂质中心与长波光学声子的相互作用.研究结果表明,In0.19Ga0.81N/GaN量子阱材料中光学声子和内建电场对束缚极化子能量和结合能的贡献很大,它们都引起能量和结合能降低.结合能随着阱宽的增大而单调减小,窄阱中减小的速度快,而宽阱中减小的速度慢.不同支声子对能量和结合能的贡献随着阱宽的变化规律不同.没有内建电场时,窄阱中,定域声子贡献小于界面和半空间声子贡献,而宽阱中,定域声子贡献大于界面和半空间声子贡献.有内建电场时,定域声子贡献变小,而界面和半空间声子贡献变大,声子总贡献也有明显变化.在In0.19Ga0.81N/GaN量子阱中,光学声子对束缚极化子能量和结合能的贡献比GaAs/Al0.19Ga0.81As量子阱中的相应贡献(约3.2—1.8和1.6—0.3 meV)约大一个数量级.阱宽(d=8 nm)不变时,在In0.19Ga0.81N/GaN量子阱中结合能随着杂质中心位置Z0的变大而减小,并减小的速度变快.随着Z0的增大,界面和半空间光学声子对结合能的贡献缓慢减小,而定域光学声子的贡献缓慢增大.     

温度对抛物量子阱中极化子能量的影响

采用线性组合算符法和幺正变换法研究温度对抛物型量子阱中极化子基态能和基态结合能的影响. 通过理论推导得到极化子基态能和基态结合能的表达式. 结合量子统计力学中平均声子数的表达式, 得到极化子基态能量和基态结合能与温度的函数关系. 在不同温度下, 分别讨论了极化子基态能量和基态结合能与电子-声子耦合强度和阱宽的关系, 阱深取不同值时讨论了极化子基态能和基态结合能随温度的变化规律. 计算结果表明, 极化子的基态能量和基态结合能都是温度的递增函数.     

Interface phonons and dielectric enhancement effects on excitons in quantum well

The theory of exciton polaron in quantum well is developed. The interaction with symmetric interface phonons is shown to contribute significantly to polaron exciton binding energy. As a result, this energy depends both on effective masses of charge particles in the quantum well and on polarization properties of the barriers. The conditions are found for strong exciton–phonon coupling in quantum well.     

Bound polaron in a spherical quantum dot under an electric field

A variational approach is used to study the ground state of a bound polaron in a spherical quantum dot under an external electric field. The binding energy of the hydrogenic impurity state is calculated by taking the interaction of an electron with both the confined longitudinal optical phonons and the surface optical phonons into account. The interaction between impurity and longitudinal optical phonons has also been considered to obtain the binding energy of a bound polaron. It shows that the polaron effects give significant corrections to the binding energy and its Stark energy shift. The external electric field increases the phonon contributions to the binding energy.     

Bound polaron in a wurtzite GaN/AlxGa1 − xN ellipsoidal finite-potential quantum dot

A variational method is used to study the ground state of a bound polaron in a weakly oblate wurtzite GaN/Al_xGa_1 − xN ellipsoidal quantum dot. The binding energy of the bound polaron is calculated by taking the electron couples with both branches of LO-like and TO-like phonons due to the anisotropic effect into account. The interaction between impurity and phonons has also been considered to obtain the binding energy of a bound polaron. The results show that the binding energy of bound polaron reaches a peak value as the quantum dot radius increases and then diminishes for the finite potential well. We found that the binding energy of bound polaron is reduced by the phonons effect on the impurity states, the contribution of LO-like phonon to the binding energy is dominant, the anisotropic angle and ellipticity influence on the binding energy are small.     

ZnSe/ZnS抛物量子阱中激子的极化子效应(英文)

采用推广的LLP方法研究了ZnSe/ZnS抛物量子阱中激子的极化子效应。考虑电子和空穴与LO声子的相互作用,得到了激子基态能量和结合能随阱宽的变化关系。结果表明,阱宽较小时,能量随着阱宽的增大而急剧减小;阱宽较大时,能量减小的比较缓慢。和我们以前的工作对比,我们发现ZnSe/ZnS抛物量子阱对激子的束缚强于GaAs/Ga1-xAlxAs抛物量子阱。     

The phonon effects on the impurity states in cylindrical quantum wire with a finite confining potential

The variational method and the effective mass approximation are applied to calculate the binding energies of the hydrogenic impurity states in a cylindrical quantum wire with finite deep potential well. The phonon effects on the impurity states are considered by taking both the couplings of the electron-phonon and the impurity ion-phonon into account. The numerical results for the GaAs cylindrical quantum wire are given and discussed. It is found that the ion-phonon interaction reduces the impurity binding energy and supplies key contribution to the energy shift, but the electron-phonon coupling enhances the binding energy less. Longitudinal optical (LO) phonons play more important role than interface optical (IO) phonons in the impurity potential screening. The polaron effect caused by LO phonons is more important when the wire is thinner, otherwise the LO phonons are dominant for the thicker wires.     

A bound polaron in a spherical quantum dot

The binding energy of a bound polaron in a spherical quantum dot has been investigated by using the variational method. The influence of LO and SO phonons have taken into consideration. Result shows that the phonon contribution to the binding energy is dependent on the size of the quantum dot as well as the position of the impurity in the quantum dot. Numerical calculation on the ZnSe quantum dot shows that such contribution is about 5% to 20% of the total binding energy. Received: 13 October 1997 / Revised: 4 March 1998 / Accepted: 26 May 1998     

Phonon effect on binding energies of impurity states in cylindrical quantum wires of polar semiconductors under an electric field

Phonon effect on hydrogenic impurity states in cylindrical quantum wires of polar semiconductors under an applied electric field is studied theoretically by a variational approach. The binding energies are calculated as functions of the transverse dimension of the quantum wire, and the donor-impurity position under different fields. The electron–phonon interaction is considered in the calculations by taking both the confined bulk longitudinal optical phonons and interface optical phonons as well as the impurity-ion–phonon coupling. The numerical results for the CdTe and GaAs quantum wires are given and discussed as examples. It is confirmed that the electron–phonon interaction obviously reduces both the binding energy and the Stark energy-shift of the bound polarons in quantum wires.     

外电场下极性量子阱中杂质态结合能

我们用变分方法研究了外电场下量子阱中的杂质态结合能,计算中既考虑了电子同体纵光学声子和界面光学声子的相互作用又考虑了杂质中心同体纵光学声子和界面光学声子的相互作用。我们以GaAs/Al_0.3Ga_0.7As量子阱为例,讨论了结合能随杂质位置、阱宽和电场强度的变化规律。得到了电子-声子相互作用对杂质态结合能和斯塔克效应的修正是相当明显的。