Defect formation in wurtzite a-plane GaN grown on r-plane sapphire was studied using transmission electron microscopy. The observed defect pattern grown along the [11-20] direction shows significant differences compared to films grown along the [00•1] direction. Predominant line defects identified in the a-plane GaN were Frank-Shockley partial dislocations bounding basal plane stacking faults and originating at the film/substrate interface. In order to understand the impact of the anisotropic elastic properties of the wurtzite structure on the dislocation formation and the stress around the dislocations anisotropic plane strain elasticity theory was applied and compared with results obtained from isotropic theory calculations. Furthermore, dislocation properties were calculated for AlN and InN. It was found that the line energy found for InN amounts only to about one third of the values obtained for GaN and AlN.

The Role of Anisotropy for Defect Properties in a-Plane GaN. R.Kröger, T.Paskova: Proceedings of the SPIE, 2008, 6894, 689403