The morphology of etch pits on a sapphire surface

In this work, the pits were successfully etched onto (0 0 0 1) or (1 1 over(2, -) 0) sapphire single crystal surfaces by using a Na₂B₄O₇ solution. The difference in the morphology of etch pits on different planes of the sapphire was examined by atomic force microscopy measurements. It was found that the size of the etch pits was affected by the etching duration. The results of X-ray diffraction analysis also indicated the particular in-plane orientation of the etch pits on the sapphire surface. The relationship between the morphology of etch pit and the sapphire structure will be explained in the paper. In addition, the etching rates for the (0 0 0 1) and (1 1 over(2, -) 0) types of sapphire will be compared.