Characterization of defects in β-Ga 2 O 3 single crystals

We have investigated defects in beta-type gallium oxide (β-Ga 2 O 3 ) single crystals by X-ray topography, selective etching, and transmission electron microscopy. Two types of defects, namely, dislocations and nanopipes, were found. Dislocations are screw dislocations with Burgers vector parallel to [010]. The majority of them lie on and (001). Nanopipes are hollow pipes of 0.1 µm diameter and of at least 15 µm length elongated along [010]. No strain field was found around them. From the observation results, we have discussed the formation mechanisms of these defects.