Theory of Brillouin scattering in anisotropic, piezoelectric semiconductors

Abstract

A theory of Brillouin scattering in piezoelectric semiconductors is presented. The formula derived for the differential-scattering cross section is valid for crystals of any symmetry and of any optical or acoustic anisotropy in any direction. The scattered light intensity is calculated on the basis of a new dyadic Green's function for radiation in anisotropic conducting media. The expression for the phonon-induced fluctuation in the dielectric-constant tensor is extended to incorporate the contributions from the free-carrier-screened indirect photoelastic effect and from the free-carrier plasma. By using the Boltzmann equation, the phonon-induced self-consistent electric field arising from the piezoelectric coupling and the deformation potential coupling is calculated. The influence of a spatial exponential growth or decay in the phonon beam intensity on the scattering cross section is considered.