PHOTOREFLECTANCE AND THERMOREFLECTANCE STUDIES OF STRAINED-LAYER In_(0.2)Ga_(0.8)As/GaAs MULTIPLE QUANTUM WELLS STRUCTURE
In_（0．2）Ga_（0．8）As／GaAs应变多量子阱结构的光调制反射和热调制反射谱的研究

The studies of experimental results in strained In0.2Ga0.8 As/GaAs multiple quantum wells structure by using photoreflectance(PR)and thermoreflectance(TR)techniques at 77K were presented' With a least square' fit of lineshape function,the intersubband transitions in PR spectra can be clearly identified in the multiple quantum wells and compared with an envolope-function calculation. From a comparison of the PR and TR spectra at 77K of a strained InGaAs/GaAs multiple quantum wells structure,it can be confirmed that the first derivative nature of electric field modulation relates to the uncoupled 11H and 13H transitions,and the low field modulation produces a third-derivative line shape related to the coupled states (the tunneling effect between wells).