Confined phonons in GaAs/AlAs superlattices with periodically corrugated interfaces

Using resonant Raman spectroscopy we have studied novel GaAs/AlAs superlattice (SL) structures, grown on (113) substrates, where the GaAs and AlAs layer widths vary periodically on a nanometer scale along the lateral [110] direction. We observe sharp confined LO phonon lines for both (113) and simultaneously grown (001) SLs, for a range of different layer widths, whose frequencies map the bulk GaAs LO dispersion. The confined phonon lines of the (113) SLs show a side peak, which can be assigned to a mode with finite k vector parallel to the layers, induced by the lateral periodicity.