CONSEQUENCES OF INTERFACE CORRUGATION ON THE LATTICE-DYNAMICS AND RAMAN-SPECTRA IN HIGH-INDEX ALAS GAAS SUPERLATTICES/

We have studied the effect of the interface corrugation on the Raman r esponse of (113), (112), (331) and (012)-oriented AlAs/GaAs superlatti ces. The phonon frequencies and displacements have been calculated usi ng the bond charge model and a supercell approach, and the Raman spect ra have been calculated using the bond polarizability model. In(113)-o riented superlattices, the corrugation would give rise to an additiona l mode coupling and an enhancement of the phonon confinement. The magn itude of these effects and the consequent modifications on the Raman s pectra would be quite different for the two interface structures propo sed in the literature. For the (112), (331) and (012) superlattices, t he modifications induced by the in-plane periodicity would be weak, ev en in the case of ultrathin superlattices. This is due to the very sma ll height of the interface corrugation and also because the proposed l ateral periodicity would not induce any significant mode coupling.