Energy Transfer Between Femtosecond Laser and Silicon Carbide

The femtosecond laser ablation of a wide bandgap semiconductor is characterized by a complicated energy transfer and rarely explored process. A coupled two-temperature-Fourier heat conduction model is developed to investigate the energy deposition and material removal mechanisms of femtosecond laser ablating silicon carbide (SiC). Absorption mechanisms, temperature distribution, and threshold fluence are investigated. Non-thermal melting and thermal melting processes are calculated. The results show that during the interaction between laser and SiC, the main absorption mechanism was governed by multiphoton absorption and Auger recombination. Simulation results of the new model show that the influence of latent heat on lattice temperature is insignificant and the heat accumulation on the surface is little. The obtained damage threshold represents reasonable prediction, based on comparison with experimental and literature data. The damage threshold and the non-thermal melting threshold for 800 nm increase with the pulse duration. The thermal melting occurs immediately after non-thermal melting at high fluence. The molten layer thickens logarithmically with the increase of the fluence.