ELASTIC LIGHT-SCATTERING FROM SEMICONDUCTOR STRUCTURES - LOCALIZED VERSUS PROPAGATING INTERMEDIATE ELECTRONIC EXCITATIONS

We present a theoretical study of the relative role of localized and p ropagating intermediate electronic states in the processes of elastic scattering of light. Only localized excitations lead to isotropic scat tering in lowest-order perturbation theory. Inhomogeneous broadening o f the optical transition affects the scattering efficiency from the or dered and disordered array of localized states in a qualitatively diff erent 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 sug gested 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 favorab le systems for studying the role of propagating electronic excitations .