合金无序和界面不平整对InGaAs/GaAs应变量子阱光谱展宽的影响

Influences of Alloy Disorder and Interface Roughness on Optical Spectra of InGaAs/GaAs Strained-Layer Quantum Wells

用光荧光和光吸收的实验方法研究了InGaAs/GaAs应变量子阱低温下的光谱展宽机理。实验观察到激子谱线半宽随着InGaAs层厚度和In的组分增加而增大。采用有效晶体近似的方法分析了实验数据,发现样品中合金组合无序引起的激子谱线展宽是主要的光谱展宽机理。实验中还发现与轻空穴有关的吸收光谱结构在升温过程中由吸收峰变为台阶状的谱结构。该现象可用与轻空穴有关的吸收为空间间接跃过来解释。

We present studies of alloy composition and layer thickness dependences of exciton linewidthsin InGaAs/GaAs strained-layer quantum well grown by MBE, using both photoluminescenceand optical absorption. It is observed that linewidths of exciton spectra increase withindium content and well size.Using the virtual crystal approximation, the experimental dataare analyzed.The results obtained show that the alloy disorder is the dominant mechanismfor line broadening at low temperatures.ln adeition,it is found that the absorption spectrumrelated to light hole transitions has varied from a peak to step-like structure as the temperatureincreases.This behavior can be understood by the space-indirect transition of lightholes.