First-principles total-energy calculations were performed for [00•1] screw dislocations in GaN, with |b| = c. These indicated that a model which involved a helical Ga-filled core was more stable, than a hollow-core model, under Ga-rich conditions. This model gave rise to electronic states which were dispersed throughout the band gap. Such a dislocation was therefore expected to be a very strong center for non-radiative recombination, and a pathway for current leakage.

Screw Dislocations in GaN: the Ga-Filled Core Model. J.E.Northrup: Applied Physics Letters, 2001, 78[16], 2288-90