LIGHT-SCATTERING BY A MULTICOMPONENT PLASMA COUPLED WITH LONGITUDINAL-OPTICAL PHONONS - RAMAN-SPECTRA OF P-TYPE GAAS-ZN

The LO-phonon-hole-plasmon coupling is investigated for p-type III-V s emiconductors. Due to a large carrier damping, only one coupled LO-pho non-plasmon mode (CPPM) appears. Expressions for the theoretical Raman scattering efficiency of a multicomponent plasma are derived in the r andom phase approximation. They take into account wave-vector-dependen t intraband transitions within the heavy-and light-hole bands as well as interband transitions between them. Finite lifetime effects were in cluded in a generalized Mermin approximation. The theoretical band sha pes of the CPPM at different temperatures are compared with Raman meas urements of Zn-doped p-type GaAs in the hole concentration range p=10( 17)-10(20) cm(-3). At low temperatures the contribution of the interba nd transitions cannot be neglected in the frequency range of the CPPM, resulting in a mode broadening. Agreement between the theoretical ban d shapes and the Raman spectra is obtained without any fit parameter i f the hole concentration p and the mobility mu are derived from the me asured Hall values p(H) and mu(H) evaluated on the basis of a two-band model of the conductivity. Raman measurements of the CPPM in Zn-doped p-type GaP show a different temperature dependence, which is explaine d by the different ratio of the light-to the heavy-hole effective mass on the interband transitions.