Subsurface-damaged layer in (010)-oriented β-Ga2O3 substrates

Abstract
Subsurface damage (SSD) in chemical mechanical polishing (CMP)-finished (010)-oriented β-Ga2O3 substrates was investigated using optical microscopy and X-ray topography (XRT). Damaged layers at the surface of (010)-oriented substrates caused by lapping and mechanical polishing had measured thicknesses of 50 μm and 20 μm, respectively, but no detectable damage was caused by CMP. The damage remained as SSD underneath the CMP-finished surface unless the SSD was completely removed by heat treatment. XRT images of an SSD-free (010)-oriented substrate prepared using CMP after heat treatment unambiguously showed dislocations and twin boundaries.