耦合GaN/Al_xGa_(1-x)N量子点的非线性光学性质

Nonlinear Optical Properties in Wurtzite GaN/Al_xGa_(1-x)N Coupled Quantum Dots

在有效质量和偶极矩近似下,考虑了由于压电极化和自发极化所引起的内建电场和量子点的三维约束效应,对纤锌矿对称Al_xGa_(1-x)N/GaN/Al_xGa_(1-x)N/GaN/Al_xGa_(1-x)N圆柱型应变耦合量子点中激子非线性光学性质进行了研究。计算结果表明,内建电场使吸收光谱向低能方向移动,发生红移现象,并且使吸收峰强度大大减小。量子限制效应使光吸收峰强度随着量子点尺寸的减小而增强,并且随着量子点尺寸的减小,吸收光谱发生蓝移现象。

Based on effective-mass and the dipole approximation, considering the effect of the strong built-in electric field due to the piezoelectricity and spontaneous polarization and the effect of the 3D confinement of the electron and hole in quantum dots （QDs）, the exciton optical transition absorption coefficient is calculated in symmetric wurtzite AlxGa1-xN/GaN/AlxGa1-xN/GaN/AlxGa1-xN coupled QDs. Numerical results show that the strong built-in electric field in the symmetric AlxGa1-x N/GaN/ AlxGa1-xN/GaN/AlxGa1-xN strained coupled QDs leads to absorption curve shifting to low energy, and makes the exciton absorption peak intensity decreased remarkably. Moreover, the sizes of quan- tum dots also have a great influence on the exciton optical absorption coefficient. When the sizes of quantum dots decrease, the exciton absorption coefficient intensity shows a marked increment, and leads to absorption spectra shifting to high energy.