Photoreflectance study of holehyphen;subband structures in GaAs/InxAl1minus;xAs strainedhyphen;layer superlattices

摘要

We have performed photoreflectance measurements of the exciton transitions associated with the first (n=1) subbands in GaAs(dGAring;)/InxAl1minus;xAs(dIAring;) strainedhyphen;layer superlattices with (dG,dI,x)=(100,100,0), (100,100,0.1), (100,100,0.2), and (40,40,0.2) grown on (001) GaAs substrates. The photoreflectancehyphen;intensity profiles of then=1 excitons, which reflect the oscillator strength, clearly demonstrate that the order of then=1 Verbar;J=3/2,mJ=plusmn;3/2ge; (heavyhyphen;hole) subband and then=1 Verbar;3/2,plusmn;1/2ge; (lighthyphen;hole) subband is changed by the In concentration (latticehyphen;mismatch strain) and the layer thickness (quantumhyphen;size effect). We have analyzed the experimental results of the holehyphen;subband order as a function of the In concentration and the layer thickness on the basis of an effectivehyphen;mass approximation taking into account strain effects.