Interband transitions in strained InGaAs/AlAsSb multiple-quantum-well structures

Room temperature photoreflectance (PR) was performed on strained In{sub x}Ga{sub 1-x}As/AlAsSb quantum wells (QWs) grown on InP substrates. We observed clear and well-resolved structures, which could be attributed to the interband optical transitions originating in the QWs. By comparing the transition energies measured from the PR spectra with those theoretically calculated from the confined energy levels in the QWs, we confirmed that the value of the conduction band offset of In{sub 0.8}Ga{sub 0.2}As/AlAsSb was close to 1.7 eV and the nonparabolicity of the conduction band of In{sub 0.8}Ga{sub 0.2}As was between 2.25 and 2.5, which is higher than that obtained using a three-band model.