Excimer laser induced thermal evaporation and ablation of silicon carbide

Generally laser ablation of materials is performed at laser fluences above a definite threshold for which a dense plume of energetic particles is ejected from the irradiated target and considerably high ablation rate is achieved. No particular effort has been devoted to correlate the film quality to the employed laser fluence, also in correlation with different possible ablation mechanisms of ablation. We have performed measurements of ablation rate on silicon carbide single crystal targets by XeCl laser pulses as function of the laser fluence and we have investigated the angular distribution of the emitted material through the measurements of the thickness of the deposited films as well as the morphology of the craters in the irradiated targets as a function of the laser fluence. We have also modelled the melting dynamics and calculated the surface temperature and the consequent 'pure thermal' evaporation following each laser pulse by using the well known 'thermal model' often used for the laser annealing. In the presented paper we show that SiC ablation behaviour depends on the laser fluence so that three phenomenologically different energy density ranges may be defined.