Optical properties of ionized donor-bound excitons confined in strained wurtzite ZnO/Mg_xZn_(1-x)O quantum dots  

作　　者：郑冬梅 王宗篪 肖波齐 

机构地区：[1]College of Electromechanical Engineering, Sanming University

出　　处：《Journal of Semiconductors》2015年第3期46-51,共6页半导体学报（英文版）

基　　金：Project supported by the National Natural Science Foundation for Young Scientists of China(No.11102100);the Program for New Century Excellent Talents in Fujian Province University(No.JA14285);the Program for Young Top-Notch Innovative Talents of Fujian Province of China

摘　　要：Within the framework of the effective-mass approximation and the dipole approximation, considering the three-dimensional confinement of the electron and hole and the strong bulk-in electric field （BEF） in strained wurtzite ZnO/Mgo.25Zno.750 quantum dots （QDs）, the optical properties of ionized donor-bound excitons （D^＋, X） are investigated theoretically using a variational method. The computations are performed in the case of finite band offset. Numerical results indicate that the optical properties of （D^＋, X） complexes sensitively depend on the donor position, the QD size and the BEF. The binding energy of （D^＋, X） complexes is larger when the donor is located in the vicinity of the left interface of the QDs, and it decreases with increasing QD size. The oscillator strength reduces with an increase in the dot height and increases with an increase in the dot radius. Furthermore, when the QD size decreases, the absorption peak intensity shows a marked increment, and the absorption coefficient peak has a blueshift. The strong BEF causes a redshift of the absorption coefficient peak and causes the absorption peak intensity to decrease remarkably. The physical reasons for these relationships have been analyzed in depth.Within the framework of the effective-mass approximation and the dipole approximation, considering the three-dimensional confinement of the electron and hole and the strong bulk-in electric field （BEF） in strained wurtzite ZnO/Mgo.25Zno.750 quantum dots （QDs）, the optical properties of ionized donor-bound excitons （D^＋, X） are investigated theoretically using a variational method. The computations are performed in the case of finite band offset. Numerical results indicate that the optical properties of （D^＋, X） complexes sensitively depend on the donor position, the QD size and the BEF. The binding energy of （D^＋, X） complexes is larger when the donor is located in the vicinity of the left interface of the QDs, and it decreases with increasing QD size. The oscillator strength reduces with an increase in the dot height and increases with an increase in the dot radius. Furthermore, when the QD size decreases, the absorption peak intensity shows a marked increment, and the absorption coefficient peak has a blueshift. The strong BEF causes a redshift of the absorption coefficient peak and causes the absorption peak intensity to decrease remarkably. The physical reasons for these relationships have been analyzed in depth.

关 键 词：ZnO quantum dot ionized donor-bound exciton binding energy oscillator strength absorption coefficient 

分 类 号：TN304.2[电子电信—物理电子学]