摘要
研究了抛物量子点中弱耦合束缚极化子的性质。采用线性组合算符和幺正变换方法导出了束缚极化子的振动频率和基态能量。讨论了量子点的有效受限长度、电子-LO声子耦合强度和库仑场对抛物量子点中弱耦合极化子的振动频率和基态能量的影响。数值计算结果表明:弱耦合束缚极化子的振动频率和基态能量随有效受限长度的增加而减小,振动频率随库仑势的增加而增加,基态能量随耦合强度、库仑势的增加而减小。
With the development of several experimental techniques, for example, molecular beam epitaxy, metal-organic chemical-vapour deposition and electron beam lithography combined with reverse mesa etching, there has been a lot of work devoted to the understanding of hydrogenic-impurity states in low-dimensional semiconductor heterostructures such as quantum wells, quantum wires and quantum dots. In recent years, there has been great interest in investigating quantum dots both theoretically and experimentally. Due to the small structures of QD＇s, some physical properties such as optical and electron transport characteristic are quite different from those of the bulk materials. The study of the impurity states in these low dimensional structures is an important aspect to which many theoretical and experimental works based. Recent investigations in the reduced dimensionality show the impurity within the reduced dimensionality shows that the impurity binding energy will be enhanced with the deduction of the dimensionality. The problem of a bound polaron in a quantum dot has been of considerable interest. Woggon et al. studied the states of polarons bound in a potential and determined the local optical absorption spectrum up to firstorder time-dependent perturbation theory with respect to the electron-phonon interaction. Chen et al. derived the expression of the ground-state energy of an electron coupled simultaneously with a Coulomb potential and a longitudinal-optical phonon field in parabolic quantum dots and wires within the framework of Feynman variational path-integral theory. Wang et al. investigated effects of LO phonon for the hydrogen-like impurity in a semiconductor quantum dot. Melnikov et al. studied the effect of the electron-phonon interaction on an electron bound to an impurity in a spherical quantum dot embedded in a nonpolar matrix theoretically. Xie et al. investigated the binding energy of a bound polaron in a spherical quantum dot by using the variational method, and so on. However, few investigators studied the bound polaron in the quantum dot with the linear combination operator and a perturbation method so far. By using the linear combination operator and unitary transformation method, properties of the bound polaron in a parabolic quantum dot are studied for the weak electron-LO-phonon coupling case. Results show that the ground state energy of the bound polaron decreases with the increasing of Coulomb potential, the effective confinement length and the electron-LO-phonon strength increasing. The vibration frequency decreases with the effective confinement length and it increases when the ground energy and the vibration frequency decrease with quantum size effects of a parabolic quantum dot. Coulomb potential enhanced. Meanwhile, that the the effective confinement length increasing reveals
出处
《发光学报》
EI
CAS
CSCD
北大核心
2005年第5期564-568,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金(10347004)
内蒙高校科研基金(NJ04117
NJ03072)资助项目
关键词
抛物量子点
弱耦合
束缚极化子
有效受限长度
parabolic quantum dot
weak coupling
bound polaron
effective confinement length
作者简介
陈英杰（1974-），女，山东乐陵人，硕士研究生，主要从事凝聚态光学性质的研究。
肖景林：通讯联系人；E—mail：xiaojlin@126．com，Tel：（0475）8313561.
