Lattice dynamical properties of cubic CdS/ZnSe strained-layer superlattices

We investigate the lattice dynamics of cubic CdS/ZnSe strained-layer superl attices grown on GaAs (001). Concerning the longitudinal vibrations our cal culations based on a linear-chain model predict for this AB/CD-type superla ttices confined optical and folded acoustic phonons as well as localized an d extended interface modes. The calculated energies agree very well with th e experimentally observed frequencies in Raman scattering experiments. BE u sing the bond polarizibilty model we discuss the relative scattering intens ities of the different modes. The intensity of the localized Zn-S interface mode is of the order of the confined modes. The observation of this mode i s supported by the behaviour of the overtone scattering of the longitudinal optical modes. (C) 3000 Elsevier Science B.V. All rights reserved.