Identification and Reversible Optical Switching of NV+ Centers in Diamond

Abstract Positive nitrogen‐vacancy centers (NV + ) in diamond are predicted to exist in conjunction with neutral (NV 0 ) and negative (NV − ) centers. However, the existence of NV + has only been indirectly inferred through a shift of the Fermi level. Evidence of NV + coexisting with NV 0 and NV – in diamond has not yet been observed. In this paper, positron annihilation spectroscopy in combination with in situ light illumination is applied, in order to investigate the presence of NV + centers in nitrogen implanted and subsequently annealed diamond. Switching of NV + to NV 0 centers is observed with a threshold photon energy of 1.234(8) eV. In complete darkness, a decay of NV 0 centers with a decay time of 1.73(22) h can be detected. In conclusion, previously converted NV 0 centers are metastable and partially decay in darkness, leading to the reformation of NV + centers.