Investigation of threading dislocation atomic configurations in GaN by HRTEM, geometrical phase analysis and atomistic modelling

The dislocation core distribution maps and in-plane Burgers vector components are derived from the experimental strain tensor by applying the continuum dislocation theorem and geometric phase analysis. Atomic configuration of 7/5 and 8 atom cycles are identified in experimental HRTEM images of edge threading dislocations in GaN layers. This was possible by a careful analysis of the splitting of dislocation density distribution peaks in these images and simulated ones using an edge dislocation model calculated from a modified Stillinger-Weber potential.