Electronic structures of GaN edge dislocations

We investigate atomic and electronic structures of the threading edge dislo cations of GaN using self-consistent-charge density-functional tight-bindin g approaches. Full-core, open-core, Ca-vacancy, and N-vacancy edge dislocat ions are fully relaxed in our total-energy scheme. The Ca-vacancy dislocati on is the most stable in a wide range of Ga chemical potentials, whereas fu ll-core and open-core dislocations are more stable than others in the Ga-ri ch region. Partial dehybridization takes place during the lattice relaxatio n near the dislocation in all cases. The dangling bonds at Ga atoms mostly contribute to the deep-gap states, whereas those at N atoms contribute to t he valence-band tails. All the edge dislocations can act as deep trap cente rs, except the Ga-vacancy dislocation, which may act as an origin of yellow luminescence.