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抛物量子点中弱耦合束缚极化子的相互作用能
引用本文:尹辑文,于毅夫,肖景林.抛物量子点中弱耦合束缚极化子的相互作用能[J].发光学报,2005,26(3):304-308.
作者姓名:尹辑文  于毅夫  肖景林
作者单位:1. 内蒙古赤峰学院, 物理系, 内蒙古, 赤峰, 024000;2. 内蒙古民族大学, 物理与机电学院, 内蒙古, 通辽, 028043
基金项目:国家自然科学基金;内蒙古高等学校科研项目
摘    要:研究了抛物量子点中弱耦合束缚极化子的性质,采用改进的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、有效质量和相互作用能。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、有效质量和相互作用能的影响。数值计算结果表明:弱耦合束缚极化子的振动频率和相互作用能随有效受限长度的减少而急剧增大,振动频率随库仑势以及电子LO声子耦合强度的增加而增加,而相互作用能随库仑势以及电子LO声子耦合强度的增加而减小。有效质量仅与电子LO声子耦合强度有关。

关 键 词:抛物量子点  有效质量  库仑势
文章编号:1000-7032(2005)03-0304-05
收稿时间:2004-12-25
修稿时间:2004年12月25

Interaction Energy of Weak-Coupling Bound Polaron in a Parabolic Quantum Dot
YIN Ji-wen,YU Yi-fu,XIAO Jing-lin.Interaction Energy of Weak-Coupling Bound Polaron in a Parabolic Quantum Dot[J].Chinese Journal of Luminescence,2005,26(3):304-308.
Authors:YIN Ji-wen  YU Yi-fu  XIAO Jing-lin
Institution:1. Inner Mongolia Chifeng College, Chifeng 024000, China;2. College of Physics and Electromechanics, Inner Mongolia National University, Tongliao 028043, China
Abstract: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.In recent years, the physical characteristic of a bound polaron in a quantum dot has been of considerable interest. Wang et al. investigated influence of the LO phonon on the ground state energy of the hydrogen-like impurity in a spherical semiconductor quantum dot by using variational method. 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 dot and wires within the frame-work of Feynman variational path-integral theory are derived by Chen et al.. Melnikov et al. studied the effect of the electron-phonon interaction on an electron bound of an impurity in a spherical quantum dot embedded in a nonpolar matrix theoretically. The all-coupling variational method is used to calculate the polaron energy shift including interaction with both bulk and surface LO phonons.Bound polarons are discrete, confined electronic states, spatially localizd due to a local potential (V(r),)but sharing a common phonon state of the surrounding crystal. Woggon and Miller studied the energy states of (polarons) bound in a potential and determine the local optical absorption spectrum using first-order time-(dependent) perturbation theory with respect to the electron-phonon interaction. However, few of investigators studied the bound polaron in the quantum dot with the improving linear combination operator (method) so far.In the present paper, by using the improving linear combination operator and unitary transformation me-(thod,) properties of the bound polaron in a parabolic quantum dot are studied for the weak electron-LO-phonon coupling case. Results show that the interaction energy of the weak-coupling bound polaron will decreases with increasing the Coulomb potential, the effective confinement length of quantum dot and the electron-LO-phonon coupling strength increasing. The vibration frequency of the weak-coupling bound polaron will decrease with increasing the effective confinement length,but will increase with increasing the Coulomb potential and the (electron-LO) phonon coupling strength. Meanwhile, the interaction energy and the vibration frequency will increase sharply with decreasing the effective confinement length. Those attribute to interesting quantum size effects.
Keywords:parabolic quantum dot  effective confinement length  Coulomb potential
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