Atomic intermixing in short period GaAs/AlAs superlattices

We compare the confined optical frequencies measured by Raman scattering and predicted by ab initio lattice dynamics including atomic intermixing. We combined the structural information deduced from both GaAs and AlAs phonons. The residual Ga (Al) concentrations in the AlAs (GaAs) layers is estimated. They strongly decrease with decreasing growth temperature. However, a significant amount of gallium in the AlAs is evidenced even at 400-degrees-C.