MOLECULAR-DYNAMICS SIMULATION OF LASER-ABLATION OF SILICON

Laser ablation of silicon surfaces has been investigated by molecular dynamics (MD) simulations. Results for laser pulse lengths of 200 fs, 1 ps and 5 ps have been obtained for different pulse energy densities. Structures of approximately 100 Angstrom x 100 Angstrom were simulate d. In some cases the impact of up to five successive laser pulses was studied. Calculations of up to 20 ps after the onset of the laser have been performed. The major part of the atoms is removed on a picosecon d time scale even for fs laser pulses. Pressure waves running through the crystal could be traced. Recrystallization of melted silicon leads to irregular crystalline structures around the ablated hole. Redeposi tion of atoms on the surface could be observed.