Line-shaped defects in bulk β-Ga2O3 single crystals grown by the vertical Bridgman method

We conducted an investigation of line-shaped defects, extending in the < 010 > direction, in bulk beta-Ga2O3 single crystals grown by the vertical Bridgman (VB) method. Parallelepiped cross-section samples with {010} polished surfaces and {100} cleavage planes were prepared and were then etched in phosphoric acid at 140 degrees C. Rhombic etch pits were observed on the (010) surface and they were similar in shape to those reported as nanometer-sized grooves or plate-like nanopipes in crystals grown by the edge-defined film-fed growth (EFG) method. Groove-like voids in the < 010 > direction were also observed on {100} cleavage planes below the etch pits observed on the {010} surface. Therefore, we concluded that line-shaped defects observed in VB-grown crystals are similar to defects observed in EFG-grown crystals. The size of these defects was considerably smaller than that observed in EFG-grown crystals, but with a density of 5 x 10(5) cm(-2). Based on these results, possible formation mechanisms for such defects were discussed. (c) 2023 The Japan Society of Applied Physics