内建电场和杂质对双电子柱形量子点系统束缚能的影响

摘要/Abstract

摘要：

在有效质量近似下，采用变分法，研究了内建电场和杂质对双电子柱形GaN/AlxGa1-xN量子点系统束缚能的影响。结果表明：杂质带负电时，体系基态能量都比较大，不易形成稳定的束缚态。带电量为e的施主杂质位于量子点中心时，杂质电子的束缚能随量子点高度和半径的增加先缓慢增大后减小，存在最大值；随着Al含量的增加，体系的束缚能增大。随着杂质从量子点下界面沿z轴移至上界面，体系的束缚能先增大后减小。与单电子杂质态相比，内建电场对双电子量子点系统束缚能的影响比较显著；当量子点高度L<6nm时，杂质双电子量子点系统的束缚能大于单电子杂质态束缚能，而当量子点高度L>6nm时，杂质双电子量子点系统的束缚能小于单电子杂质态束缚能。

关键词: 光电子学, 柱形量子点, 内建电场, 杂质, 束缚能

Abstract:

Based on the framework of effective-mass approximation and variational approach, The influence of built-in electric field and an impurity on the binding energy of a cylindrical wurtzite GaN/AlxGa1-xN quantum dot(QD) with two electrons is discussed. The numerical results show that while the charge of impurity is negative, the impurity state would be instable. When there is a donor impurity with positive charge e in the center of QD , the binding energy of impurity to electron firstly increases rapidly, reachs a maximum value, then decreases with increasing the height and radius of QD. With increasing Al content, the binding energy increases monotonically. The binding energy of impurity to electron firstly increases, and then decreases with moving the impurity position from the bottom of QD to the top, there is a maximum. In comparison with the single-electron impurity states, the influence of the built-in electric field on the binding energy of two-electron quantum dot system is more obvious. While the QD height L is smaller than 6nm in the WZ GaN/Al0.15Ga0.85N QD with the radius R=5nm, the binding energy of two-electron quantum dot system with impurity would be larger than that of the single-electron impurity states. while the QD height L is larger than 6nm, the binding energy of two-electron quantum dot system with impurity would be smaller than that of the single-electron impurity states.

Key words: optoelectronics, cylindrical quantum dot, built-in electric field, impurity, two-electron, binding energy

中图分类号:

O472

郑冬梅王宗篪苏春燕. 内建电场和杂质对双电子柱形量子点系统束缚能的影响[J]. J4, 2011, 28(1): 96-103.

ZHENG Dong-mei, WANG Zong-chi, SU Chun-yan. Effect of built-in electric field and impurity on binding energy of cylindrical quantum dot with two electrons[J]. J4, 2011, 28(1): 96-103.

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