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 (Ns), the vacancy (V), and related point defects (NV, NVH, N2, N2V, and V2) 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 V2 pairs during postirradiation annealing. Divacancies may pin the Fermi level, making the NV defects neutral.