Surface modification of 4H-SiC using femtosecond and picosecond lasers

Femtosecond (FS) and picosecond (PS) lasers were used to modify the surface of 4H-SiC wafers, and the effects of laser pulse duration and power on surface roughness, ablation depth, depth uniformity, surface morphology, and phase transition were investigated. The results indicate that FS laser produces greater ablation depth due to its higher peak power compared to PS laser, but also results in a significant increase in surface roughness and a decrease in surface uniformity. Regarding the phase transition, both FS and PS lasers cause the decomposition of SiC into amorphous silicon (a-Si), disordered carbon (C), and graphite. However, the intense ablation by the high-power FS laser leads to a substantial reduction in the disordered C and graphite components.