纤锌矿ZnSnN_(2)/In_(x)Ga_(1-x)N柱形量子点中的激子态和带间光跃迁  

Exciton States and Interband Transitions of Wurtzite ZnSnN_(2)/In_(x)Ga_(1-x)N Cylindrical Quantum Dot

作　　者：郑冬梅[1,2] 黄思俞[1,2] 许晓赋[1,2] ZHENG Dong-mei;HUANG Si-yu;XU Xiao-fu(College of Electromechanical Engineering,Sanming University,Sanming 365004,China;Key Laboratory of Intelligent Equipment of Fujian Higher Education Institution,Sanming University,Sanming 365004,China)

机构地区：[1]三明学院机电工程学院,福建三明365004 [2]三明学院装备智能控制福建省高校重点实验室,福建三明365004

出　　处：《量子光学学报》2021年第4期342-351,共10页Journal of Quantum Optics

基　　金：福建省自然科学基金项目(2020J01387)。

摘　　要：基于有效质量近似和变分原理,考虑内建电场效应和量子点的三维约束效应,理论研究了纤锌矿ZnSnN_(2)/In_(x)Ga_(1-x)N柱形量子点中基态激子结合能、带间发光波长、激子辐射寿命随量子点尺寸(高度L和半径R)及In_(x)Ga_(1-x)N中In含量x的变化关系,并与In_(x)Ga_(1-x)N量子点的激子态和带间光跃迁作比较。结果表明:当x<0.3时,基态激子结合能随着量子点尺寸及In含量的增加而减小。激子带间发光波长随量子点尺寸的增大而红移;随着In含量的增加,当量子点高度L<2.2 nm(L>2.2 nm)时,发光波长红移(蓝移)。激子辐射寿命随着量子点尺寸的增加而增加,随着In含量的增加而减小。此外,随In含量增加而线性减小的内建电场使基态激子结合能减小,带间发光波长红移,激子辐射寿命增大。受沿着异质结生长方向的内建电场的影响,量子点高度L的变化对激子光学性质的影响要比量子点半径R的变化对激子光学性质的影响更显著。而与In_(x)Ga_(1-x)N量子点相比,ZnSnN_(2)/In_(x)Ga_(1-x)N量子点中激子的结合能、带间发光波长及激子辐射寿命都较大,尤其对于In含量小的量子点。Based on the effective-mass approximation and variational approach,the ground-state exciton binding energy,the interband emission wavelength,and the radiative lifetime as functions of the quantum dot(QD)sizes(height and radius)and In content in the In_(x)Ga_(1-x)N layer are investigated theoretically in strained wurtzite(WZ)ZnSnN_(2)/In_(x)Ga_(1-x)N cylindrical QDs,with considering a three-dimensional carrier confinement in QDs and a strong built-in electric field(BEF)effect due to the piezoelectricity and spontaneous polarization.The computations are performed in the case of finite band offset.Numerical results elucidate that the ground-state exciton binding energy decreases with increasing QD sizes and In content when In content x<0.3.As In content increases,the interband emission wavelength has a red-shift if the dot height L<2.2 nm,but the interband emission wavelength has a blue-shift when L>2.2 nm.and it has a red-shift with increasing QD size.In addition,the radiative lifetime increases with increasing QD size and decreases with increasing In content.The built-in electric field decreasing linearly with In content reduces the ground-state exciton binding energy,and increases the interband emission wavelength and the radiative lifetime.Because the electric field in the ZnSnN_(2) layer exists along the grown direction of the heterostructures,the influence on the luminescent properties from height L is more visible than the influence on the luminescent properties from radius R.So,in the investigation of the luminescent properties,the BEF and the QD height L are important.Furthermore,the ground-state exciton binding energy,the interband emission wavelength,and the radiation lifetime in ZnSnN_(2)/In_(x)Ga_(1-x)N QDs are all larger than those in In_(x)Ga_(1-x)N/GaN QDs,especially for QDs with low In content.

关 键 词：ZnSnN_(2)量子点 激子 内建电场 发光波长 激子寿命 

分 类 号：TN304[电子电信—物理电子学]