Nitrogen-Vacancy Color Centers Created by Proton Implantation in a Diamond

We present an experimental study of the longitudinal and transverse relaxation of ensembles of negatively charged nitrogen-vacancy (NV−) centers in a diamond monocrystal prepared by 1.8 MeV proton implantation. The focused proton beam was used to introduce vacancies at a 20 µm depth layer. Applied doses were in the range of 1.5 × 10^13 to 1.5 × 10^17 ions / cm^2 . The samples were subsequently annealed in vacuum which resulted in a migration of vacancies and their association with the nitrogen present in the diamond matrix. The proton implantation technique proved versatile to control production of nitrogen-vacancy color centers in thin films.