Femtosecond laser ablation mechanism of 4H-SiC by two-temperature model, molecular dynamic simulations, and pump–probe experiments

Abstract

Femtosecond laser has been extensively employed in the processing of silicon carbide (SiC) due to its ultrahigh peak power and ultra-short pulse duration. However, the interaction between femtosecond laser and 4H-SiC is an extremely complex process and the material removal mechanism is still controversial. Here, the femtosecond laser ablation of 4H-SiC is investigated by combining our extended non-equilibrium two-temperature model (nTTM), molecular dynamics (MD) simulations, and pump–probe experiments. The temporal and energetic distributions of thermal and non-thermal ablation for 4H-SiC are predicted by employing an improved nTTM. In particular, the non-thermal ablation is observed to present throughout the whole ablation process, which is not highlighted in previous studies. A distinct threshold gap of 0.17 J/cm2 between thermal and non-thermal ablation obtained by the theoretical model is consistent with the pump–probe measurements. Moreover, good agreement between the results by our extended nTTM with experiment in comparison with those of the traditional TTM is obtained. Finally, the microscopic atomic configurations of thermal ablation are compared and analyzed by MD simulations and pump–probe images. This work provides a better understanding of the ablation mechanism and promotes the femtosecond laser processing technology in fields of wide-bandgap semiconductors.