Raman and cathodoluminescence study of dislocations in GaN

Structural and optical properties of freshly created and in-grown dislocations in GaN single crystal are investigated by Raman and cathodoluminescence (CL) microscopy. The introduction of a high density of dislocations by micro-indentation is accompanied by the generation of intrinsic point defects. A high amount of VGa–impurity complexes is responsible for the decrease in the free electron concentration and the enhanced yellow luminescence around the indentation. A compressive stress induced by deformation is revealed by Raman scattering and CL. In-grown dislocations are decorated with a point defect atmosphere, leading to a reduction in the free carrier concentration around the dislocation.