摘要
讨论电子与体纵光学(LO)声子弱耦合时对抛物量子线中极化子性质的影响。采用Tokuda改进的线性组合算符法、Lagrange乘子和变分法,导出了抛物量子线中弱耦合极化子的有效质量和光学声子平均数随拉格朗日乘子变化的规律及极化子振动频率随量子线约束强度的变化规律。并以ZnS量子线为例进行了数值计算,结果表明:抛物量子线中弱耦合极化子的有效质量m*和光学声子平均数N随着拉格朗日乘子u的增加而增大;该结论与体材料中结论基本一致,但量子线中的效应比体材料更明显,表明量子线对电子约束的增强,使极化子效应更明显。同时,极化子振动频率λ随约束强度ω0的增强而增大。
With recent rapid development of epitaxial techniques such as molecular beam epitaxy （MBE） and metal organic chemical vapor deposition （MOCVD） , there has been great interest in investigating quantum well and wires both in materical science and condensed state physics field. Due to the electron motion along the length of the wire is free size and is quantized in the two dimentions perpendicular to the wire in quantum wires, they had a series of new and serious special physical properties which are quite different from those of the semiconductor constituents. These had brought infinite chance and hope on development and use of new materials. Especially, electron in quantum wire was subject to a two-dimension confinement, so that quantum effect was quite different from those of the bulk metericals, these would brought about great society benefit and economic benefit. So many scientists have been investigating properties of quantum wires. Francisco has studied the hydrogenic impurity binding energy in QWWS ; Chuu et al. have calculated the energies of the ground state and the excited state in cylindrical quantum wires using Pekar alternative approach and peturbration-variational approach. Zhou and Gu have discussed the properties of polaron and magetopolaron in cylindrical quantum wires and in rectangular quantum wires by using variational solutions and linear combination operators methods. Guo et al. have investigated the electron-optic effects of double-layered quantum wires in magnetic field by means of density-matrix treatment. In this paper, taking into account the interaction of the electron with optical phonon modes in parabolic quantum wires, we have investigated weak-coupling polaron effective mass and the mean number of optical phonon by using of Tokuda＇s improved linear combination operators, the Lagrange multiplier and the variational method. Numerical calculations, for the ZnS crystal as an example, are performed. The results indicated that, both the effective mass m ^＊ of polaron and the mean number of optical phonon N increased with the increasing of Lag-range multiplier u. With the increasing of confinement strength too of quantum wire, vibration frequency λ of polaron would increase. In short, both the effective mass m^ ＊ and the mean number of optical phonon N of polaron increase with the increasing of Lag-range multiplier u as well as vibration frequency λ of polaron increase with increasing of confinement strength ω0 for weak-coupling in a parabolic quantum wire.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2005年第6期704-708,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金资助项目(10347004)
关键词
抛物量子线
极化子
有效质量
光学声子平均数
弱耦合
parabolic quantum wire
polaron
effective mass
mean number of optical phonon
weak-coupling
