| The development of laser pulse compression techniques has made it possible to examine nonequilibrium carrier distributions on time scales of a few tens of femtoseconds (10;At densities near 10;In our description, the electron distribution satisfies both the exclusion principle and uncertainty principle, while obeying a set of equations of motion which resemble those of a classical electron gas. The Coulomb interaction between electrons is simulated by a real space MD approach with the inclusion of exchange interaction. The need to satisfy the uncertainty principle gives rise to corrections to the usual Coulomb interactions.;The electron-electron interaction, together with the other carrier-phonon interactions, determines the initial thermalization of the carrier distributions. To include the electron-electron interaction in a proper way allows us to see if it is the process responsible for some experimental observations. Numerical values for the energy- and density-dependent thermalization times for the various carrier-carrier and carrier-phonon processes have been worked out theoretically using EMC/MD method, which agree with Becker's (1) photon echo experimental data. The inclusion of exchange interaction improves the agreement at the high density.;We have also calculated directly the intervalley transition rates by tracking the source as well as the destination in following intervalley population transfers. This allows us to unfold the complicated multiple pass-through intervalley scattering processes in order to gain information on the initial stages of relaxation, which is essential in developing ultrahigh speed electronic devices. |
