Folded acoustic phonons in Si-SixGe1−xsuperlattices

Abstract

Raman scattering from folded longitudinal acoustic phonons in Si-${\mathrm{Si}}_{\mathrm{x}}$ ${\mathrm{Ge}}_{1\mathrm{-}\mathrm{x}}$ superlattices is observed. The measured phonon energies are explained by use of the elastic continuum theory for the acoustic modes. This leads to an accurate determinatnion of the superlattice period.