Laser-induced melting of porous silicon

The dynamics of laser-induced melting of porous silicon (por-Si) irradiated in vacuum by nanosecond pulses of a XeC1 laser (wavelength 308 nm) is inve stigated by time-resolved reflectivity method. The laser-induced modificati ons of por-Si are monitored by SEM, FTIR and photoluminescence spectroscopy . The threshold of laser-induced melting of per-Si is found to decrease fro m 35 to 11 mJ/cm(2) with the increase of porosity from, 45% to 82%, while t he melting threshold of c-Si is 750 mJ/cm(2). A comparison between the expe rimental data and results of simulations shows that the decrease of thermal conductivity and the lowering of por-Si melting temperature are the main r easons for the diminution of the melting threshold with the increase of por osity.