Angular dispersion and polarization mixing in GaAs/AlAs superlattices grown along the [012] direction

Results of lattice-dynamical calculations of the GaAs/AlAs superlattice grown along the [012] direction are compared with Raman-scattering data. Confined phonon modes and the in-plane (interfacelike) optical modes are clearly observed at frequencies in excellent agreement with theoretical predictions. The confined phonons of the [012]-oriented superlattice have mixed longitudinal and transverse character, as a consequence of the low symmetry of this superlattice (${\mathit{C}}_2$ point group). Special emphasis is placed on the angular dispersion and mixed polarization of superlattice modes.