Density functional theory calculations were used to study the effect of doping and growth stoichiometry upon the core structure of a threading edge dislocation. Four possible candidate structures were examined, and their formation energies were found to depend strongly upon the Fermi level and growth stoichiometry. A structure with Ga vacancies at the dislocation core was predicted to be most stable in n-type material which had been grown under N-rich conditions, while a structure without vacancies was most stable in p-type material which had been grown under those conditions. In material which had been grown under Ga-rich conditions, a structure with N vacancies at the dislocation core was predicted to be most stable in p-type material. Various core structures were expected to be present in n-type material. Edge dislocations were predicted to behave as electron traps in n-type material, and could act as hole traps in p-type material; depending upon the growth conditions.

The Effect of Doping and Growth Stoichiometry on the Core Structure of a Threading Edge Dislocation in GaN. A.F.Wright, U.Grossner: Applied Physics Letters, 1998, 73[19], 2751-3