Relationship Between Propagation Angle of Dislocations in β-Ga 2 O 3 (001) Bulk Wafers and Their Etch Pit Shapes

In this study, we examined the etch pits formed by molten alkali etching on beta-gallium oxide (β-Ga 2 O 3 ) (001) bulk wafers and their dislocations to understand the behavior of crystal defects in β-Ga 2 O 3 . For this, we used focused ion beam (FIB), scanning transmission electron microscopy (STEM), and scanning electron microscopy (SEM). The FIB–STEM observation shows that the etch pits, named Cannonball type, correspond to dislocation propagation on the (100) plane, and the asymmetry of etch pit shapes is proportional to the propagation angle of dislocations. These findings allow for the determination of the propagation angles of dislocation in β-Ga 2 O 3 without using any FIB preprocessing of cross-sectional STEM observations. SEM was used to examine more than 100 Cannonball-type etch pits, and the propagation angle distribution of the associated dislocations was derived using the deviation of the core of each etch pit. Our results show that the propagation angle distribution is almost flat regardless of its angle; however, with lower occurrences at around 20° and 70°, the core deviation ratio was 1:2 in the ± [010] direction.