High-order resonant Raman scattering by combinations and overtones of interface phonons in GaAs-AlAs short-period superlattices

Abstract

We report the observation of high-order Raman scattering at the resonance with the lowest direct optical transition of GaAs-AlAs short-period superlattices. While the one-phonon spectrum involves both confined and interface modes of GaAs and of AlAs, the high-order scattering is dominated by combinations and overtones of a GaAs-like and an AlAs-like phonon of a new type, which appear to be interface modes with large in-plane wave vectors.