Influence of the carrier distribution on carrier-carrier scattering in GaAs

Hot electrons in GaAs in the presence of a highly nonequilibrium plasma generated by a 150-fs laser pulse are shown to have an energy-loss rate to the plasma that is two to four times higher than a hot electron in the presence of a cooler, thermalized plasma of the same density. The increased energy-loss rate due to the nonequilibrium plasma is consistent with the reduced screening that has been predicted for such a plasma. In addition, the linewidth of the hot acceptor luminescence peak, which is used to measure the energy-loss rate, is found to be constant under fs laser excitation as the injected carrier density is increased up to about 2×1016 cm-3. This finding disagrees with a recent prediction. Possible reasons for the disagreement are considered. © 1995 The American Physical Society.