Elastic light scattering from semiconductor structures: Localized versus propagating intermediate electronic excitations

We present a theoretical study of the relative role of localized and propagating intermediate electronic states in the processes of elastic scattering of light. Only localized excitations lead to isotropic scattering in lowest-order perturbation theory. Inhomogeneous broadening of the optical transition affects the scattering efficiency from the ordered and disordered array of localized states in a qualitatively different way. The propagating electronic excitations may only contribute to elastic light scattering via higher-order processes. The scattering of excitons by impurities or the interface roughness potential is suggested as a mechanism for the contribution of propagating excitations. An analysis of experimental data on elastic scattering of light from quantum-well structures and bulk semiconductors suggests that the bulk materials, rather than widely investigated quantum wells, are favorable systems for studying the role of propagating electronic excitations.