摘要
在有效质量近似和偶极矩近似下,考虑内建电场效应和量子点的三维约束效应,采用变分法详细研究了势垒中Mg含量和离子施主杂质中心位置对受限于纤锌矿ZnO/Mg_xZn_(1-x)O圆柱形应变量子点中离子施主束缚激子(D+,X)体系的带间光跃迁吸收系数的影响。计算结果表明:当垒中Mg含量x<0.25时,随着Mg含量的增加,(D^+,X)体系的光跃迁吸收峰向高能方向移动,出现蓝移现象;而当x>0.25时,随着Mg含量的增加,吸收曲线向低能方向移动,出现红移现象。(D^+,X)体系的带间光跃迁吸收峰强度随着Mg含量的增加而减弱。随着离子施主杂质从量子点左边界沿材料生长方向移至量子点右边界时,光跃迁吸收峰发生蓝移。当在量子点中心左侧沿径向移动离子施主杂质时,光跃迁吸收峰向高能方向移动,发生蓝移现象;而当在量子点中心右侧沿径向移动离子施主杂质时,吸收曲线发生红移现象,但离子施主杂质的掺入位置对光跃迁吸收峰强度影响不明显。
Within the framework of the single band effective-mass approximation and the dipole approximation, considering the three-dimensional confinement of the electron and hole and the strong built-in electric field（BEF） due to the spontaneous and piezoelectric polarizations in wurtzite（WZ） Zn O/MgxZn1-xO strained cylindrical quantum dots（QDs） with finite potential barriers, numerical calculations have been performed by using variational procedure. The dependence of the interband optical absorption coefficient due to an exciton bound to an ion with charge ＋e（called ionized donor bound exciton（D^＋, X）） on the Mg content x of the barrier material MgxZn（1-x）O and the position of the ionized donor has been investigated in detail. Numerical results indicate that increasing Mg content x causes a blue-shift of the absorption coefficient peak of（D^＋,X） complex if x〈0.25, while it causes a red-shift of the absorption coefficient peak if x〉0.25. The intensity of the interband optical absorption is decreased with increasing Mg content. Moreover, the absorption coefficient peak of（D^＋, X） complex is moved towards the higher energy and has a blue-shift with moving the ionized donor from the left interface of QD to the right interface along c-axis of the WZ crystal. Furthermore, the absorption peak is moved towards the higher energy and has a blue-shift with moving the ionized donor along radial direction when the donor is located in the left side of the QD, while it has a red-shift with moving the donor along radial direction when the donor is located in the right side of the QD. But the donor position has not marked effect on the intensity of the interband optical absorption.
出处
《三明学院学报》
2017年第4期8-14,共7页
Journal of Sanming University
基金
福建省自然科学基金项目(2015J01666)
国家自然科学基金项目(51576114)
福建省高等学校新世纪优秀人才支持计划(JA14285)
关键词
量子点
离子施主束缚激子
吸收系数
quantum dot
ionized donor bound exciton
absorption coefficient
