中国物理B ›› 2020, Vol. 29 ›› Issue (7): 77104-077104.doi: 10.1088/1674-1056/ab8d9d

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Exciton optical absorption in asymmetric ZnO/ZnMgO double quantum wells with mixed phases

Zhi-Qiang Han(韩智强), Li-Ying Song(宋丽颖), Yu-Hai Zan(昝宇海), Shi-Liang Ban(班士良)   

  1. School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
  • 收稿日期:2019-12-21 修回日期:2020-04-18 出版日期:2020-07-05 发布日期:2020-07-05
  • 通讯作者: Shi-Liang Ban E-mail:slban@imu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 61764012).

Exciton optical absorption in asymmetric ZnO/ZnMgO double quantum wells with mixed phases

Zhi-Qiang Han(韩智强), Li-Ying Song(宋丽颖), Yu-Hai Zan(昝宇海), Shi-Liang Ban(班士良)   

  1. School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
  • Received:2019-12-21 Revised:2020-04-18 Online:2020-07-05 Published:2020-07-05
  • Contact: Shi-Liang Ban E-mail:slban@imu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 61764012).

摘要: The optical absorption of exciton interstate transition in Zn1-xlMgxlO/ZnO/Zn1-xcMgxcO/ZnO/Zn1-xrMgxrO asymmetric double quantum wells (ADQWs) with mixed phases of zinc-blende and wurtzite in Zn1-xMgxO for 0.37< x < 0.62 is discussed. The mixed phases are taken into account by our weight model of fitting. The states of excitons are obtained by a finite difference method and a variational procedure in consideration of built-in electric fields (BEFs) and the Hartree potential. The optical absorption coefficients (OACs) of exciton interstate transition are obtained by the density matrix method. The results show that Hartree potential bends the conduction and valence bands, whereas a BEF tilts the bands and the combined effect enforces electrons and holes to approach the opposite interfaces to decrease the Coulomb interaction effects between electrons and holes. Furthermore, the OACs indicate a transformation between direct and indirect excitons in zinc-blende ADQWs due to the quantum confinement effects. There are two kinds of peaks corresponding to wurtzite and zinc-blende structures respectively, and the OACs merge together under some special conditions. The computed result of exciton interband emission energy agrees well with a previous experiment. Our conclusions are helpful for further relative theoretical studies, experiments, and design of devices consisting of these quantum well structures.

关键词: quantum well, mixed phase, exciton transition, direct and indirect exciton, optical absorption

Abstract: The optical absorption of exciton interstate transition in Zn1-xlMgxlO/ZnO/Zn1-xcMgxcO/ZnO/Zn1-xrMgxrO asymmetric double quantum wells (ADQWs) with mixed phases of zinc-blende and wurtzite in Zn1-xMgxO for 0.37< x < 0.62 is discussed. The mixed phases are taken into account by our weight model of fitting. The states of excitons are obtained by a finite difference method and a variational procedure in consideration of built-in electric fields (BEFs) and the Hartree potential. The optical absorption coefficients (OACs) of exciton interstate transition are obtained by the density matrix method. The results show that Hartree potential bends the conduction and valence bands, whereas a BEF tilts the bands and the combined effect enforces electrons and holes to approach the opposite interfaces to decrease the Coulomb interaction effects between electrons and holes. Furthermore, the OACs indicate a transformation between direct and indirect excitons in zinc-blende ADQWs due to the quantum confinement effects. There are two kinds of peaks corresponding to wurtzite and zinc-blende structures respectively, and the OACs merge together under some special conditions. The computed result of exciton interband emission energy agrees well with a previous experiment. Our conclusions are helpful for further relative theoretical studies, experiments, and design of devices consisting of these quantum well structures.

Key words: quantum well, mixed phase, exciton transition, direct and indirect exciton, optical absorption

中图分类号:  (Excitons and related phenomena)

  • 71.35.-y
78.20.Ci (Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)) 73.21.Fg (Quantum wells) 71.55.Gs (II-VI semiconductors)