In high resistance AlN irradiated with 2 MeV electrons, an electron paramagnetic resonance (EPR) spectrum, labeled EI-1, with an electron spin S = 1/2 and a clear hyperfine (hf) structure was observed. The hf structure was shown to be due the interaction between the electron spin and the nuclear spins of four 27A nuclei with the hf splitting varying between ∼ 6.0 and ∼ 7.2 mT. Comparing the hf data obtained from EPR and ab initio supercell calculations we suggest the EI-1 defect to be the best candidate for the neutral nitrogen vacancy in AlN
