Threading screw dislocations in GaN by the Heyd‐Scuseria‐Ernzerhof hybrid functional

Threading screw dislocations in wurtzite GaN are studied using Heyd-Scuseria-Ernzerhof hybrid functional with in generalized Kohn-Sham scheme. Several types of core structures, both stoichiometric and non-stoichiometric, are constructed from the unconventional dislocation line position. We computed the formation energies and compared their stabilities systematically. For the open core type structure, the equilibrium diameter is ˜ 4.9 A. With the intermediate value of Ga chemical potential, the Ga-filled type dislocation core, where N atoms near the dislocation line are removed and only Ga atoms exist, becomes the most stable structure. This dislocation core does not introduce deep empty states into the band gap, but introduces deep filled states originated from the Ga–Ga wrong bonds of Ga atoms located along the dislocation core. This leads to the band gap narrowing and degrades the electronic properties such as breakdown voltage. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)