Monte Carlo studies of nonequilibrium phonon effects in polar semiconductors and quantum wells. I. Laser photoexcitation

The present paper illustrates a series of theoretical results on nonequilibrium phonon effects based on a novel Monte Carlo algorithm. The details of the numerical procedure are given. No assumptions on the form of the phonon or the electron distributions are required. The main emphasis is given to the study of LO-phonon perturbations as a result of the relaxation of photoexcited carriers in polar semiconductors. Bulk GaAs and InP, as well as GaAs-${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As heterostructures are analyzed. Good agreement is found with available experimental results from time-resolved luminescence and Raman measurements. The strong phonon emission by the high-energy photoexcited electrons in the first stage of their relaxation (within a few tenths of a picosecond) is found to drive the phonon distribution strongly out of equilibrium. After the excitation, reabsorption of the emitted phonons by the carriers and nonelectronic phonon-decay processes bring the distribution back to its equilibrium value.