Theory of inelastic light scattering off acoustic modes in superlattices

Abstract

A theory of inelastic normal-incidence backscattering of light off the acoustic modes of a two-component superlattice is considered. The appropriate Green function, derived in an earlier paper (see ibid., vol.18, p.1269, 1985) is used here to derive the scattering cross-section for two cases. In the first, the absorption of light by the superlattice is assumed to be negligibly small. With such a simplification it is possible, as a useful guide, to evaluate the intensities of the light scattering peaks and to explore their variations with the superlattice acoustic mismatch parameter. In the second case the opacity of the medium to light is taken into account. The spectrum predicted by the theory is presented for a GaAs-Ga_1-xAl_xAs superlattice with x approximately=0.4 and equal superlattice layer thicknesses, and exhibits a number of features which are pointed out and discussed.