The (00•1) surface of GaN single crystals and (¯1¯1¯1)-oriented GaAs wafers were deformed using a Vickers indenter with two different orientations at room temperature. Dislocations and cracks at the indentations were observed by means of scanning electron microscopy, cathodoluminescence, light microscopy and transmission electron microscopy. Between dislocations, cracks and the orientation of the indenter, geometrical relations could be found. The GaN and GaAs samples were indented with loads in the range of 0.02 to 4.90N and 0.02 to 1.00N, respectively. In both materials, the dislocation rosettes correspond to the symmetry of the indented surface. In (00•1) GaN, the crack system was predominantly determined by the symmetry and orientation of the indenter. In contrast, the crack formation in (¯1¯1¯1)-GaAs was determined by the symmetry of the crystal and consisted of different types of radial cracks with different probabilities.

Dislocations and Cracks at Vickers Indentations in GaN and GaAs Bulk Crystals. I.Ratschinski, H.S.Leipner, F.Heyroth, W.Fränzel, R.Hammer, M.Jurisch: Physica Status Solidi C, 2011, 8[4], 1325–9