The relative stabilities of specific atomic models of the b = c[00•1] screw dislocation in GaN were calculated by using density-functional theory. The calculations showed that the dislocation core structure and electrical activity changed as the chemical potential of Ga varied across the thermodynamically allowed range. Under Ga-rich conditions, the core region was filled with Ga atoms and these atoms formed a pair of helical chains. Under N-rich conditions, a core structure containing both Ga and N atoms was most stable. Both types of dislocations gave rise to bands of electronic states deep within the gap. The conditions required for H to passivate the screw dislocation were determined.

Theory of Intrinsic and H-Passivated Screw Dislocations in GaN. J.E.Northrup: Physical Review B, 2002, 66[4], 045204 (5pp)