Extended defects such as dislocations were induced by the nano- and micro-indentation of GaN layers, grown by molecular beam epitaxy onto 6H-SiC. The resultant local variations in the strain and optical properties were investigated using spectrally and spatially resolved cathodoluminescence techniques. The micro-indentation caused the evolution of dark-line defects, compressive strain within the region of the defects and cracking along directions determined by the symmetry of the arrangement of dark-line defects. The evolution of extended dark-line defects was correlated with the dislocation structure, which was analyzed via transmission electron microscopic measurements of the plastically deformed indented regions.

Indentation of GaN - a Study of the Optical Activity and Strain State of Extended Defects. U.Jahn, A.Trampert, T.Wagner, O.Brandt, K.H.Ploog: Physica Status Solidi A, 2002, 192[1], 79-84