Inelastic light scattering from strained-layer [formula omitted] superlattices

Abstract

We have studied strained-layer Si Ge superlattices (SL) composed of ultrathin (3–6 ML) Ge layers by inelastic light (Raman) scattering. The SL's with periods ranging from 27 to 72 Å have been grown on Si (100) by MBE. Folded longitudinal acoustic phonons up to the fourth order have been observed indicating abrupt interfaces and exellent uniformity in the growth direction. The energy of the optical modes of the Ge layers is shifted due to strain. The observed shift is consistent with the calculated value obtained using uniaxial stress parameters.