The relaxation process of a dense carrier population created by a light pulse in a polar semiconductor is examined. We analyze the influence of screening in the electron-electron and electron-phonon interactions as well as phonon heating effects upon the thermalization process of the carrier system and the subsequent cooling process. We perform our study by incorporating screening and phonon population effects into a phenomenological model previously proposed to explain some characteristics of the steady-state luminescence of GaAs under high density of excitation. Specifically, the time required for the carrier system to thermalize, the temperature at which this occurs, and the time evolution of the carrier temperature are examined as functions of the carrier density of excitation, the energy of excitation, and the light-pulse duration. We conclude that the thermalization process is mainly affected by a long-lived phonon population created by the relaxing carriers and that phonon heating and screening effects affect the cooling process at different densities of excitation and at different time intervals.

• Received 19 August 1986

DOI:https://doi.org/10.1103/PhysRevB.35.6318