The behavior of interstitial Mg atoms at an edge dislocation was studied in the wurtzite-type GaN crystal by molecular dynamics simulation. Parameters for a two-body interatomic potential were determined by the Hartree-Fock ab initio method. First, an edge dislocation extending to the [00▪1] direction was generated in an molecular dynamics basic cell composed of about 11000 atoms. Second, Mg atoms were placed at substitutional and interstitial positions in the molecular dynamics basic cell, and the Mg atoms were traced. It was found that the diffusivity of Mg atoms at a dislocation was enhanced along the dislocation. At 1000K, the diffusivity of interstitial Mg atoms inside the dislocation core was approximately 3 orders of magnitude larger than that of interstitial Mg atoms located outside the dislocation. The enhanced diffusion along the dislocation originated from unbalanced atomic forces between the Mg atom and surrounding atoms.

Magnesium Diffusion at Dislocation in Wurtzite-Type GaN Crystal. K.Harafuji, K.Kawamura: Japanese Journal of Applied Physics, 2005, 44[9A], 6495-504