Numerical investigation of ultrashort laser damage in semiconductors

A complete self-consistent model for transport dynamics in semiconductors caused by ultrashort-pulse laser heating is presented based on the relaxation-time approximation of the Boltzmann equation. Carrier-lattice nonequilibrium interactions are simulated to obtain the temporal and spatial evolution of the carrier density and temperature as well as the lattice temperature. It is shown that the calculated damage threshold based on the carrier density criterion agrees fairly well with the experimental data for both Si and Ge semiconductors, especially for sub-picosecond pulses. It is also found that one-photon absorption and Auger recombination are the two critical factors that influence the electron-hole carrier generation.