Subsurface-damaged layer in (010)-oriented β -Ga 2 O 3 substrates

Abstract Subsurface damage (SSD) in chemical mechanical polishing (CMP)-finished (010)-oriented β -Ga 2 O 3 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 μ m and 20 μ m, 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.