Atomic-level modeling of a silicon nanofilm irradiated by ultrashort-pulsed laser bursts

Abstract

Atomic-level simulations of a silicon nanofilm irradiated by ultrashort-pulsed laser bursts were performed using the molecular dynamics coupled with an ultrafast energy transport model. The effects of pulse number in a laser burst and separation time between pulses on the thermomechanical response of the irradiated film were investigated. The numerical results showed that for laser bursts with an identical total energy, the more the pulses or the longer the pulse separation time, the lower the carrier temperature and number density. The same trend was also observed for the lattice temperature at the total laser fluence 0.1 J/cm2 but 0.18 J/cm2, as a result of the dynamical change in optical properties. It was also found that the induced thermal stress wave was weakened by increasing either pulse separation time or pulse number in a laser burst.