Defect distribution in β -Ga2O3 single crystal via selective wet etching

Dislocation density in β-Ga2O3 has been determined by chemical etching for four (100), (010), (001), and (2̄01) orientated samples by employing a distillation apparatus to maintain the etch conditions where dislocations and voids can be well identified. Severe non-uniform distribution of etch pits was found where mean and standard deviation of dislocation density from a large amount of measurements are proposed for evaluating the quality of the β-Ga2O3 single crystal. It was found that (001) orientated sample has the minimum mean dislocation density around 103 cm−2, one order less than the other orientated samples. Intertwined dislocations for the (010) orientated sample, single dislocation lying on (100) for the (001) orientated sample, and a stack of dislocations lying on the (2̄01) plane for the (100) orientated sample have been observed. The anisotropy growth of dislocations and voids, their migration and interaction, and direction-dependent etch rate are believed to be the root cause for the formation of a variety of etch patterns and orientation-related dislocation densities. With higher etchant concentration, less etch time and lower magnification images are suggested for accurately computing the etch pit density.