The behavior of Ga and N vacancies (Schottky defects, Frenkel defects), lattice-site and interstitial Mg atoms and interstitial H atoms were studied in wurtzite-type crystals using molecular dynamic simulation. Parameters for a two-body interatomic potential were determined by using the Hartree-Fock ab initio method. When Schottky defects were present, Ga and N vacancies were often paired and the paired vacancies repeatedly formed and disappeared during the simulation. When Frenkel defects were present, interstitial Ga or N atoms became lattice-site members via the substitutional-interstitial mechanism. The lattice-site Mg atom was in a very stable state, stayed there for a long time and underwent thermal vibration. The interstitial Mg atom was in a semi-stable state at the cage center of a hexagonal crystal structure. The Mg atom underwent thermal vibration there, then hopped from one cage-center to an adjacent one. Diffusivity of interstitial Mg atoms on the (00•1) plane was predominant compared with diffusivity along the [00•1] direction.

Molecular Dynamics of Magnesium Diffusion in Wurtzite-Type GaN Crystal. Harafuji, K., Tsuchiya, T., Kawamura, K.: Japanese Journal of Applied Physics - 1, 2004, 43[2], 522-31