A hybrid method for integrated atomistic-continuum simulation of ultrashort-pulsed laser interaction with semiconductors

摘要

A numerical method coupling the molecular dynamics and the two-step energy transfer model is presented for simulating ultrafast responses of semiconductors irradiated by ultrashort-pulsed lasers. In this method, an additional damping force characterizing the carrier-lattice heat exchange is added to the equations of motion of atoms in the molecular dynamics. The explicit finite difference algorithms are applied for obtaining the laser energy distribution and the carrier density evolution, whereas a semi-implicit finite difference scheme is developed as for the carrier temperature field. Examples of a thin silicon film subjected to femtosecond laser heating are utilized to validate and demonstrate this hybrid method. Results show that the proposed method is able to effectively describe not only the thermal transport but also the thermal stress wave in the ultrafast laser-semiconductor interactions.