ULTRAFAST RELAXATION OF HIGHLY PHOTOEXCITED CARRIERS IN P-TYPE AND INTRINSIC GAAS

The thermalization and energy relaxation of highly photoexcited carriers in p-type and intrinsic GaAs is investigated at room temperature using an ensemble Monte Carlo approach. We present an alternative model for treating carrier-carrier scattering in Monte Carlo simulations. The model takes into account the wave vector and frequency dependence of the dielectric function by using a screened Coulomb potential in q space due to a charge moving at the velocity of the center of mass of the interacting particles. In comparison to the statically screened model, the calculated effective carrier temperatures for an excitation density of 2 x 10(18) cm(-3) are in good agreement with the experimental results for both p-type and intrinsic GaAs. At the lower doping and excitation density of 2.5 x 10(16) cm(-3), the dynamic and the static screening models result in a comparable time evolution of the carrier energies and band populations.