Raman Study of Order and Disorder SiGe Ultrathin Superlattices

We present a Raman scattering study of ultrathin SiGe superlattices. The spectra show evidence for the formation of superlattice structures with disordered interfaces. We explain the Raman peak energies in terms of strain and confinement effects and present a simple model for the Raman spectrum, from which we obtain semiquantitative information on the degree of superlattice ordering.