量子阱中极化子的声子平均数

采用有效质量近似下的变分法,考虑到电子同时与表面光学声子和体纵光学声子相互作用,研究了无限深量子阱中极化子的表面光学声子平均数,体纵光学声子平均数和光学声子平均数。讨论了电子与体纵光学声子耦合强度α,阱宽L和势垒材料Al_xGa_1-xAs中Al的含量x对上述光学声子平均数的影响。以GaAs/Al_xGa_1-xAs量子阱为例进行了数值计算。结果表明:量子阱中表面光学声子平均数随耦合强度α,阱宽L和Al含量x增大而增大。量子阱中体纵光学声子平均数随耦合强度α,阱宽L的增大而增大。光学声子平均数随耦合强度α,阱宽L和Al含量x的增大而增大。

Mean Number of Phonons of Polaron in Quantum Well

With the technological progress in material growth, semiconductor quantum wells and heterostructures were obtained experimentally. There has been considerable interest in physical properties of low-dimensional material. Using perturbation method, Hai studied the energy and effective mass of polaron in Q2D system, in calculation, the interface phonon, 3D bulk phonon mode, parabolic quantum wells , infinite and finite quantum wells have been taken into account. Zheng studied the ground state energy and effective mass of a Q2D polaron system in a Qw by using a modified Lee-Low-Pines transformation. Mori and Ando obtained that the effects for electron and different phonon mode interaction have the same result as bulk phonon mode. Employing second order perturbation theory, intermediate coupling theory and interpolation formula, Sarma discussed the influence of electron-LO phonon interaction on the electronic properties of single two dimensional electronic slab. By using the standard perturbation theory within the Thomas-Fermi approximation, Comas and Racker calculated self-energy of weak coupling laron in a finite and infinite QW by means of polaron. Li investigated the Stark energy shifts of a bound poperturbation-variation method. Ren carried out the FeynmanHaken path integral theory to calculated the ground state energy of polaron in parabolic quantum well. Eerdun studied the temperature dependence of properties of electron-bulk LO phonon interaction system in a quantum well within the electronic-magnetic fields along the growth axis by means of variational wave-function and harmonic oscillator algebra method and he also obtained the self-energy of the system at a finite temperature. Although the properties of polaron in QW were studied by many methods, the study about the mean number of polaron in QW are seldom investigated. The properties of polaron in infinite quantum well were studied by using variational method within the effective-mass approximation. Numerical calculations, taking GaAs/ AI~Ga1_~As quantum well as an example, are performed. The results show that,the mean number of the surface optical phonon nk and the bulk Longitudinal optical phonon nq of the polaron in a quantum well will increase with increasing the electron-phonon coupling strength a, the well width L and the AI concentration x and with the increasing the electron-phonon coupling strength, the well width L and the AI concentration x, the mean number of the optical phonon N is increased.