Optical studies in ${\mathrm{In}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As/GaAs strained-layer superlattices

We studied the low-temperature photoluminescence, transmission, and the room-temperature Raman scattering spectra of ${\mathrm{In}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As/GaAs strained-layer superlattices. The strain in each type of layer was determined from the Raman measurements. From photoluminescence and transmission spectra we determined the energy difference between the confined states of electrons in the conduction band and the strain-split heavy and light holes in the valence band. From these differences we obtain values for the band offset at the ${\mathrm{In}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As/GaAs heterojunction.