Raman scattering in superlattices: Anisotropy of polar phonons

Abstract

Raman experiments on polar phonons in GaAs-Ga1−xAlxAs superlattices are reported. Other data from the literature, and its interpretation in terms of folding of the phonon Brillouin zone and scattering from q≠0 phonons induced by electronic zone folding, are discussed. An alternative explanation is presented based on optical anisotropy induced by layering. Numerical results show good agreement with experiment.