Breakdown of equilibrium approximation for nanosecond laser-induced electron emission from silicon

We demonstrate that nonequilibrium carrier dynamics play a significant role in nanosecond laser-induced electron emission from semiconductor surfaces. Surface emission current and electron yields due to thermionic and photoelectric effects are calculated for a 2 ns laser pulse irradiation, with fluences below the threshold for melting. The photoelectric effect is found to dominate electron emission only at low fluences, whereas thermionic emission from interband absorption is responsible for electron emission at high incident fluences. The results present a satisfactory interpretation of experimental observations for nanosecond laser-induced electron emission from silicon.