Optical characterization of nitrogen-vacancy centers created by proton implantation in diamond

We report the results of high-energy (1.8 MeV) proton implantation in a type-Ib diamond. The focused ion beam was used to introduce vacancies in a 20 µm-deep layer with applied doses in the range of 10¹³ to 10¹⁶ ions/cm² . The sample was subsequently annealed in vacuum which resulted in migration of vacancies and their association with the nitrogen present in the diamond matrix. We studied properties of the formed nitrogen-vacancy centers with photoluminescence and optically detected magnetic resonance. The samples are aimed to be used in sensing applications, e.g., magnetometry and bio-magnetic imaging.