Reduced cooling rates of electrons in degenerately p-doped GaAs

We performed femtosecond time-dependent luminescence measurements on highly p-doped GaAs samples. By analysis of the temporal evolution of the luminescense spectra, we determined the energy loss rate of minority electrons created during excitation. For hole concentrations p < 2 x 10(19) cm(-3), it is well known that the energy loss rate increases with increasing doping concentration. In this study, we have found for p = 2 x 10(19) cm(-3) at T-sample = 100 K that the energy loss rate as a function of doping concentration exhibits a maximum. Using Monte Carlo simulations. we have been able to interpret this maximum as due to a gradual crossover from plasmon-mediated scattering at lower hole densities to quasistatically-screened single-particle scattering at higher hole densities.