• dislocations;
  • cracks;
  • GaN;
  • GaAs;
  • indentation


The (0001) surface of GaN single crystals and (equation image)-oriented GaAs wafers have been 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 N to 4.90 N and 0.02 N to 1.00 N, respectively. In both materials, the dislocation rosettes correspond to the symmetry of the indented surface. In (0001) GaN, the crack system is predominantly determined by the symmetry and orientation of the indenter. In contrast, the crack formation in (equation image) GaAs is determined by the symmetry of the crystal and consists of different types of radial cracks with different probabilities. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)