Light scattering from quantum confined and interface optical vibrational modes in strained-layer GaSb/AlSb superlattices

Abstract
Raman scattering has been performed on GaSb/AlSb strained-layer superlattices with periods varying from 65 to 300 Å. Discrete quantum confined GaSb longitudinal optical phonons are observed in GaSb layers less than 25 Å thick. The confinement-induced Γ-to-L crossover in GaSb manifests itself in our spectra via the observation of optical-phonon density-of-states structure. This structure disappears for GaSb layers thicker than 50 Å. Spatially extended interface modes have been observed in all superlattices in both the GaSb and AlSb optical-mode spectra.