Effects of laser parameters on surface morphology and phase composition in 4H-SiC laser surface modification

Laser surface modification of 4H-SiC was conducted to investigate the effects of laser processing parameters on ablation depth, surface roughness, surface morphology, and phase composition. The results demonstrate that the femtosecond (FS) laser produces a greater ablation depth and a more pronounced increase in surface roughness compared to the picosecond (PS) laser. In addition to pulse duration, key factors influencing ablation depth and surface roughness include laser power, scanning speed, and scanning interval. The PS laser results in more significant surface oxidation. Both PS and FS lasers lead to the transformation of 4H-SiC into amorphous silicon (a-Si), disordered carbon, and graphite. In contrast to the PS laser, the high-power FS laser significantly reduces the content of disordered carbon and graphite. These effects are primarily attributed to the higher peak energy density of the FS laser, which drives more intensive ablation, and the longer interaction time of the PS laser, which leads to stronger thermal effects. These findings provide valuable insights into the mechanism of laser-SiC interaction and offer a basis for optimizing process parameters in laser surface modification applications.