Formation of NV centers in diamond: A theoretical study based on calculated transitions and migration of nitrogen and vacancy related defects

Formation and excitation energies as well charge transition levels are determined for the substitutional nitrogen (N-s), the vacancy (V), and related point defects (NV, NVH, N-2, N2V, and V-2) by screened nonlocal hybrid density functional supercell plane wave calculations in bulk diamond. In addition, the activation energy for V and NV diffusion is calculated. We find good agreement between theory and experiment for the previously well-established data and predict missing ones. Based on the calculated properties of these defects, the formation of the negatively charged NV center is studied, because it is a prominent candidate for application in quantum information processing and for nanosensors. Our results indicate that NV defects are predominantly created directly by irradiation, while simultaneously produced vacancies will form V-2 pairs during postirradiation annealing. Divacancies may pin the Fermi level, making the NV defects neutral.