We use first-principles calculations to investigate the electronic structure, atomic geometries and formation energies of point vacancies (V B , V N ), antisites (B N , N B ) and interstitials (Bi , Ni ) in cubic boron nitride (c-BN). We find that nitrogen and boron vacancies exhibit the lowest formation energies in nonstoichiometric c-BN for p-type and n-type conditions, respectively, showing intrinsic donor(V B ) and acceptor (V N ) characters. The equilibrium geometries show large outward breathing relaxations for both vacancies and for B N , with slight Jahn-Teller distortions from Td symmetry. For N B we nd an off-center distortion inducing a negative-U behavior in this center. For both interstitial centers we find stable confi- gurations in which an atomic pair occupies a nitrogen site in the lattice, N-N for Ni and N-B for Bi . These systems are stable for the different charge states investigated.
