Dislocation slip behaviors in high-quality bulk GaN investigated by nanoindentation

The dislocation slip behaviors in GaN bulk crystal are investigated by nanoindentation, the dislocation distribution patterns formed around an impress are observed by cathodoluminescence(CL) and cross-sectional transmission electron microscope(TEM). Dislocation loops, vacancy luminescence, and cross-slips show hexagonal symmetry around the 11-20 and 1-100 direction on c-plane. It is found that the slip planes of dislocation in GaN crystal are dominated in {0001}basal plane and {10-11} pyramid plane. According to the dislocation intersection theory, we come up with the dislocation formation process and the related mechanisms are discussed.