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 epita xial GaN thin film by 266-nm laser ablation coupled with a vacuum ultr aviolet (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. S canning probe microscopy measurement indicates that the surface of the etched films was structurally well defined and cleanly patterned. Mic ro-Raman measurement of ablated SiC samples, and micro-photoluminescen ce 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 s tructure. (C) 1998 Elsevier Science B.V.