Resonant light scattering induced by Coulomb interaction in semiconductor microstructures

Abstract

We consider inelastic light scattering by electron excitations in a two-dimensional electron system, which is induced by the Coulomb coupling between the Fermi sea and the interband excitons. The distinguishing feature of this mechanism of inelastic light scattering is a strong enhancement of the intensity in resonance with high two-dimensional subbands. Such resonant behaviour of the light scattering was observed in recent experiments for a two-dimensional electron plasma, quantum wires, and dots. In this paper we focus on the effect of the normal electric field on the intensity of the light scattering. We show that the interference between various virtual processes leads to the specific electric field dependence of the intensity. The intensity of the light scattering by charge-density excitations as a function of the normal electric field has a maximum at non-zero field. This maximum arises from the Coulomb direct interaction between the polarized exciton and the electron gas. Light scattering by spin-density excitations is assisted by the exchange interaction, and its intensity decreases with increasing electric field.