The dislocation multiplication and movement mechanism in GaN single crystals was studied using nano-indentation and cathodoluminescence. Dislocation loops could multiply and moved from plane to plane by cross-slip, thus producing a wide plastic deformation in GaN during indentation. This mechanism was further supported by the remarkable movement of indentation-induced dislocations during annealing. Furthermore, the so-called pop-in events, in which the indenter suddenly enters deeper into the material without the application of any additional force, could be better understood by considering the cross-slip mechanism.

Dislocation Cross-Slip in GaN Single Crystals under Nanoindentation. J.Huang, K.Xu, X.J.Gong, J.F.Wang, Y.M.Fan, J.Q.Liu, X.H.Zeng, G.Q.Ren, T.F.Zhou, H.Yang: Applied Physics Letters, 2011, 98[22], 221906