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

摘要

We investigate the lattice dynamics of cubic CdS/ZnSe strained-layer superlattices grown on GaAs (001). Concerning the longitudinal vibrations our calculations based on a linear-chain model predict for this AB/CD-type superlattices confined optical and folded acoustic phonons as well as localized and extended interface modes. The calculated energies agree very well with the experimentally observed frequencies in Raman -scattering experiments. By using the bond polarizibilty model we discuss the relative scattering intensities 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 is supported by the behaviour of the overtone scattering of the longitudinal optical modes.