Combined wave based optical analysis and particle based thermal analysis of nanoscale ultrafast target heating of silicon utilizing a near-field scanning optical probe and a femtosecond laser

A non-equilibrium wave based optical-thermal analysis was developed to study target heating and mass removal for irradiation with a femtosecond laser pulse utilizing a near-field scanning optical microscope probe. It was found that under the conditions when nano-craters were observed experimentally with a pure silicon target (Wen et al 2007 Appl. Phys. Lett. 91 251113) that the calculated electron temperature and electron number density are high enough to induce non-thermal mass removal. Also, the shapes of the nano-crater patterns are consistent with the calculated Joule heating distribution. The results indicate that near-field laser radiation-material interaction is a potential mechanism for forming nano-craters on semiconducting materials.