Precise microfabrication of wide band gap semiconductors (SiC and GaN) by VUV-UV multiwavelength laser ablation

High-quality deep etching of single crystal 6H-SiC substrate and epitaxial GaN thin film by 266-nm laser ablation coupled with a vacuum ultraviolet (VUV) Raman laser (133-184 nm), followed by chemical treatment in HF for SiC and HCl solution for GaN is demonstrated. The etch rate was as high as 35 nm pulse-1 for SiC and 55 nm pulse-1 for GaN. Scanning probe microscopy measurement indicates that the surface of the etched films was structurally well defined and cleanly patterned. Micro-Raman measurement of ablated SiC samples, and micro-photoluminescence measurement of ablated GaN samples revealed no severe damage to the optical properties or the crystal structure. The mechanism of the VUV-266 nm laser ablation of SiC and GaN is discussed based on the band structure.