Relationships between the concentrations of neutral (N0) and charged (N+) single substitutional N and N-V complexes in chemical vapour-deposited films were studied. The films were about 0.2mm-thick, and contained N impurity concentrations of 10ppm. The films were subjected to 8MeV electron irradiation at room temperature, and were then annealed at 800C. The samples were analysed by using micro-photoluminescence, visible and infra-red absorption, and electron spin resonance techniques. It was found that the concentrations of N in the N-V and N forms, in as-grown films, were less than 0.1% and 10% of the neutral substitutional N content, respectively.

Relative Abundance of Single and Vacancy-Bonded Substitutional Nitrogen in CVD Diamond. I.I.Vlasov, V.G.Ralchenko, A.V.Khomich, S.V.Nistor, D.Schoemaker, R.A.Khmelnitskii: Physica Status Solidi A, 2000, 181[1], 83-90

[34