Study on the damage and growth characteristics and mechanism of 4H-SiC crystal induced by ultrashort pulse laser

Background Silicon carbide (SiC) crystal possesses excellent physical properties, including a wide band gap, high breakdown field strength, high thermal conductivity and a low thermal expansion. These attributes make SiC highly valuable for applications in new energy vehicles, power grid equipment, aerospace, and other fields. However, due to its extremely high hardness, traditional contact processing is difficult to meet the processing requirements of high efficiency and high precision.

Purpose The use of ultra-short pulse laser with high peak intensity has become an effective way to solve this problem. In this paper, the material removal effect and material transformation and spatial distribution of SiC surface irradiated by ultrashort pulse laser under different pulse conditions are studied.

Methods By systematically adjusting the pulse duration, laser energy and pulse number, the variation of the processing properties of different SiC materials under ultrashort pulse laser irradiation have been revealed. The processing morphology was observed by scanning electron microscopy (SEM), and the material distribution and transformation in different laser irradiation regions were analyzed by energy dispersive spectroscopy (EDS).

Results The experimental results show that under the irradiation of single pulse laser, the high purity SiC (HP-SiC) crystal achieves effective material removal by relying on the peak intensity and the very short interaction time of femtosecond and picosecond pulse laser, and the material removal area decreases significantly with the increase of pulse duration. After ultrashort pulse laser processing, nitrogen-doped SiC (N-SiC) crystals form an ablation zone characterized by randomly distributed cracks. The evolution of the ablation zone is less dependent on the pulse duration. The chemical composition changes of different irradiated areas of various SiC crystals were characterized in detail by EDS, and the processing mechanisms of laser-induced HP-SiC and N-SiC crystal surfaces under different pulse durations and pulse numbers were further discussed.

Conclusions In this paper, the processing characteristics of SiC crystals under the irradiation of ultrashort pulse laser are systematically summarized, which can provide reference for the size and ablation effect control of SiC materials.