TEMPERATURE-DEPENDENCE OF THE CROSS-SECTION FOR LIGHT-SCATTERING BY CHARGE-CARRIERS - OBSERVATION OF AN ACOUSTIC PLASMON (REVIEW)

Recent research on Raman scattering by solid-state plasmas is reviewed . The research has been particularly active on n-type InP and p-type G aAs crystals, which are new materials in semiconductor electronics. Va rious possible mechanisms for the scattering of light by charge carrie rs in direct-gap semiconductors are discussed. The characteristics of a crystal which can be determined from scattering spectra are pointed out. Certain experimental details are discussed: the scattering geomet ry, the joint monitoring of the carrier mobility and density, and the determination of the temperature dependence of the cross section. The theoretical temperature dependence of the total cross section and that of the linewidth are compared in detail with experimental results. Th e frequency dependence of the cross section for quasielastic scatterin g is a superposition of Gaussian and Lorentzian lineshapes. The observ ation of an acoustic plasmon in p-GaAs is described. The heating-effec t-induced formation and existence of an acoustic plasmon in the system of light and heavy holes are explained.