Atomic structure of dislocation cores in GaN

The atomic structures of a and c dislocation cores in the wurtzite gallium nitride have been studied by atomic computer simulation using an interatomic potential of the Stillinger-Weber type. Initially, the field of displacements is imposed according to the classical linear elasticity theory and then the system is relaxed to the minimum energy. The dislocation cores present multiple structures that can be related to the location of the dislocation line. The shape and extension of the dislocation cores are analyzed by means of the atomic relative displacements map. The core energy ${E}_{c}$ and core radius ${r}_{c}$ are determined by fitting the strain energy stored in the cylinder of radius R, centered on the dislocation line, to the expression ${E}_{s}{(R)=A}_{0}\mathrm{ln}{(R/r}_{c}{)+E}_{c}.$