The structures and formation energies of neutral and charged edge dislocations were investigated by means of density-functional calculations. Stoichiometric structures with full or open cores were considered, as well as non-stoichiometric structures with Al or N vacancies along the dislocation core. The formation energies were found to depend strongly upon the Fermi level, due to the presence of defect levels in the band-gap, and upon the growth conditions; in the case of non-stoichiometric structures. A structure with Al vacancies along the dislocation core was predicted to be most stable in n-type material that was grown under N-rich conditions. On the other hand, a N-vacancy structure was most stable in p-type material that were grown under Al-rich conditions.

A.F.Wright, J.Furthmüller: Applied Physics Letters, 1998, 72[26], 3467-9