Origins of etch pits in β-Ga2O3(010) single crystals

Abstract

Etch pits of various shapes were observed on etched β-Ga2O3(010) single crystals and classified into types A-F according to shape. Type-A etch pits changed in shape in the order of types B, C, and D by etching. Groove-shaped pits observed on as-grown β-Ga2O3(010) single crystal surfaces [K. Hanada et al., Jpn. J. Appl. Phys. 55, 030303 (2016)] were classified into type G. Type-G pits, which were determined to be void defects because of three-dimentional spaces in single crystals, existed before etching and changed to type A after etching. Therefore, after etching, void defects must change in shape as follows: Type G → A → B → C → D. The exposed facets change with etching time. Types-E and-F etch pits were observed to be parallelograms and hexagons, respectively. Types-E and-F etch pits must include dislocations along the [010] direction because they did not change in shape after etching.