Effect of laser-induced antidiffusion on excited conduction electron dynamics in bulk semiconductors

By including the effect of local fluctuations in the electron kinetic energies, the kinetic Fokker-Planck-type equation for excited conduction electrons in bulk semiconductors (such as GaAs, Si, etc.) is systematically derived in the presence of a pulsed laser beyond the classical limit. A new contribution from an antidiffusion process is found as a correction to the spontaneous-phonon emission from drifting electrons in addition to contributions from joule heating and a field-dependent diffusion of electrons. The stimulated interband optical transitions of electrons from single-photon absorption are included as one of the source terms of the equation. Some possible types of damage in semiconductors including optical, electrical, and structural damage are explored. The calculated results demonstrate the existence of a kinklike feature in the electron distribution function around the edge of the conduction band due to antidiffusion. The energy spectra of the electron distribution function are studied at different times and used to analyze the transient behavior of both the conduction electron density and the hot-electron temperature.