有强内电场的GaN-基阶梯量子阱中的线性与非线性光吸收（英文）

Intersubband optical absorptions of a Ga N-based step quantum well with built-in electric field

采用密度矩阵方法,考察了带强内建电场GaN-基阶梯量子阱中的线性与非线性光吸收系数.基于能量依赖的有效质量方法,在考虑了带的非抛物性情况下,推导了结构中的精确解析的电子本征态,给出了系统中简单解析的线性与非线性光吸收系数表达式.以AlN/GaN/AlxGa1-xN/AlN阶梯量子阱为例进行了数值计算.结果发现阶梯量子阱的阱宽Lw、阶梯垒宽Lb、阶梯垒的掺杂浓度x的减小将提高体系的吸收系数.而且,随着Lw,Lb和x减小,吸收光子的能量有明显的蓝移,总吸收系数的半宽度及饱和吸收强度均减小.计算获得的部分结果与最近的实验观察完全一致.

By using the compact density matrix approach,the linear and nonlinear optical absorption coefficients in a GaN-based step quantum w ell（ QW） w ith strong built-in electric field（ BEF） have been theoretically deduced and investigated in detail. The band nonparabolicity is taken into account by using an energy-dependent effective mass（ EDEM） method. The exact electronic eigen-states in the step QW w ith strong BEF w ere obtained and the simple analytical formulas for the linear and nonlinear optical absorption coefficients in the systems w ere also deduced. Numerical calculations on an AlN / GaN / AlxGa1-xN / AlN step QW w ere performed. It is found that the decreasing of w ell w idth Lwand step barrier w idth Lband the doped concentration x in step barrier can result in the enhancement of the absorption coefficients. M oreover,w ith the decrease of Lw,Lband x,the photon energies of absorption have blue-shift,and the full-w idth-at-half-maximum of the total absorption coefficient increases and the saturation absorption intensity decrease. Some results are consistent w ith recent experimental observations.