Dislocations inhexagonal and cubic GaN

Abstract

The structure and electronic activity of several types ofdislocations in both hexagonal and cubic GaN are calculated usingfirst-principles methods. Most of the stoichiometric dislocationsinvestigated in hexagonal GaN do not induce deep acceptor states andthus cannot be responsible for the yellow luminescence. However, itis shown that electrically active point defects, in particulargallium vacancies and oxygen-related defect complexes, can betrapped at the stress field of the dislocations and may beresponsible for this luminescence. For cubic GaN, we find the idealstoichiometric 60° dislocation to be electrically activeand the glide set to be more stable than the shuffle. The dissociationof the latter is considered.