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The LO-phonon--hole-plasmon coupling is investigated for p-type III-V semiconductors. Due to a large carrier damping, only one coupled LO-phonon--plasmon mode (CPPM) appears. Expressions for the theoretical Raman scattering efficiency of a multicomponent plasma are derived in the random phase approximation. They take into account wave-vector-dependent intraband transitions within the heavy- and light-hole bands as well as interband transitions between them. Finite lifetime effects were included in a generalized Mermin approximation. The theoretical band shapes of the CPPM at different temperatures are compared with Raman measurements 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 interband transitions cannot be neglected in the frequency range of the CPPM, resulting in a mode broadening. Agreement between the theoretical band shapes and the Raman spectra is obtained without any fit parameter if the hole concentration p and the mobility are derived from the measured Hall values p₇ and ₇ 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 explained by the different ratio of the light- to the heavy-hole effective mass on the interband transitions.
Irmer et al. (Wed,) studied this question.