激子效应对抛物量子点中光电导的影响

利用记忆函数方法研究了抛物量子点中的光电导,并导出了光电导的解析表达式.以典型的GaAs/Ga1-xAlxAs抛物量子点为例作了数值计算,结果表明,在弱耦合区域,随着抛物势频率的增加,光电导会随之增强,而在强耦合区域,光电导会随之减弱;在弱耦合区域,随着抛物势频率的增加,光电导峰会向左漂移,而且抛物势频率越大,光电导曲线越不对称;考虑了激子效应后的光电导比未考虑激子效应的光电导大了10%以上.

Excitonic effect on the optical conductivity in parabolic quantum dots

The optical conductivity of parabolic quantum dots is investigated with the memory-function approach, and the analytic expression for the optical conductivity is derived. With characteristic parameters pertaining to GaAs=Ga1-xAlxAs parabolic quantum dots, the numerical results are presented. It is shown that, the optical conductivity σ(ω) increases as the frequency ω0 of the parabolic confining potential increases in the weak-confinement regime, but decreases in the strong-confine-ment regime; the peaks move to the left of the curve as the frequency ω0 of the parabolic confining potential increases, and that the larger the frequency ω0 of the parabolic confining potential, the more asymmetric the shape of the optical conductivity, in the weak-confinement regime;the optical conductivity σ(ω) considering the excitonic effects is over ten percent bigger than that without considering the excitonic effects.