EN
Native defects (vacancies, antisites and interstitials) and substitutional impurities (Mg, Zn, and C) in cubic GaN and AlN are studied by means of ab initio theoretical calculations. We examine the energetic positions of the defect levels and lattice relaxations effects. Whereas small relaxations are found in the case of vacancies, the calculations predict that large atomic displacements are associated with antisites. We also discuss the metastable behavior of the nitrogen antisite.