Single-crystal (00•1) GaN samples were deformed using a Vickers indenter at room temperature using loads in the range of 0.02 to 4.90N. Dislocations and cracks at the indentations were examined by means of scanning electron microscopy, cathodoluminescence, light microscopy and transmission electron microscopy. Geometrical relationships could be found between the dislocation arrangement, cracks and the orientation of the indenter. The orientation of the indenter had only a slight effect upon the dislocation pattern, but the crack system was determined mainly by the symmetry and orientation of the indenter.

Dislocations and Cracks at Vickers Indentations in (0001) GaN Single Crystals. I.Ratschinski, H.S.Leipner, F.Heyroth, W.Fränzel, R.Hammer, M.Jurisch: Philosophical Magazine Letters, 2010, 90[8], 565-71