Phonons in the alloy superlattice GaAs-AlxGa1−xAs

The densities of phonon states near wave vector k=0, projected onto basic vibrational states (i.e., x, y, or z vibrations of the cation or anion sublattice), are obtained for the alloy superlattice GaAs-${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As. Both confined and propagative optic phonons as well as folded acoustic phonons in the alloy superlattice are well accounted for. The results are compared with Raman data and the basic vibrations that give rise to principal features in the spectrum are identified.