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 A\r{}. Discrete quantum confined GaSb longitudinal optical phonons are observed in GaSb layers less than 25 A\r{} thick. The confinement-induced \ensuremath{\Gamma}-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 A\r{}. Spatially extended interface modes have been observed in all superlattices in both the GaSb and AlSb optical-mode spectra.