Ablation behavior and mechanism analysis of AlN single crystals induced by nanosecond laser

This study systematically investigates the ablation behavior and underlying mechanisms of nanosecond laser processing on aluminum nitride (AlN) single crystals. By comparing different post-processing cleaning strategies, the composition and formation origins of the particle-like and clustered ablation products inside the laser-etched grooves were analyzed. The results indicate that these residues mainly originate from a laser-induced melt–ejection–resolidification process. Cleaning treatments, particularly acid etching, are shown to effectively remove surface redeposits and expose the true ablation interface. Based on this, the influence of laser energy density on the groove geometry was examined. It was found that the depth-to-width ratio of the grooves increases continuously with energy density, evolving into a typical "deep-andnarrow" inverted triangular profile, consistent with the axial energy concentration characteristics of a Gaussian beam. Further Raman spectroscopy analysis reveals a progressive structural evolution of the AlN lattice under laser irradiation— from intact crystallinity to microcrystallization and eventually amorphization—along the depth direction, accompanied by stress modulation and the formation of oxide products. The findings elucidate the nanosecond laser–AlN interaction mechanisms and provide experimental insights and theoretical support for the precision fabrication of AlN-based micro/nanostructures in fourth-generation semiconductor applications.