CC BY 4.0Lagomarsino, StefanoStefanoLagomarsinoMarkešević, NemanjaNemanjaMarkeševićRashid, ZeeshanZeeshanRashidFlatae, Assegid MengistuAssegid MengistuFlataeMägdefessel, SvenSvenMägdefesselHernández-Gómez, SantiagoSantiagoHernández-GómezBianchini, GiovanniGiovanniBianchiniSledz, FlorianFlorianSledzGelli, NiclaNiclaGelliGiuntini, LorenzoLorenzoGiuntiniMassi, MirkoMirkoMassiSciortino, SilvioSilvioSciortinoCorsi, ChiaraChiaraCorsiCimalla, VolkerVolkerCimallaKnittel, PeterPeterKnittelKunzer, MichaelMichaelKunzerBellini, MarcoMarcoBelliniFabbri, NicoleNicoleFabbriAgio, MarioMarioAgio2025-08-222025-08-222025https://publica.fraunhofer.de/handle/publica/490929https://doi.org/10.24406/publica-515610.1016/j.diamond.2025.11263210.24406/publica-5156We investigate the activation yield and optical properties of the negatively charged nitrogen-vacancy (NV -) and silicon-vacancy (SiV -) centers in single-crystal diamonds, focusing on the effect of proton (p) and carbon-ion (C) irradiation on their formation. The samples, either nitrogen-rich or silicon-implanted, are grown by chemical vapor deposition or high pressure-high temperature synthesis. They are irradiated over three orders of magnitude in fluence, up to ∼1014C/cm2 or ∼ 1016 p/cm2, generating up to ∼104 ppm of extra vacancies at the end-of-range. Following thermal annealing at 1150 °C for 1 h, we characterize the samples using time-resolved spectroscopy, optical spectroscopy, and optically detected magnetic resonance. The optical properties of the NV - and SiV− centers remain stable even at vacancy concentrations of ∼103-104 ppm. At the same time, the activation yield of substitutional nitrogen and (primarily) interstitial silicon increases significantly with vacancy density, from below 2 % to approximately 15–20 % for both centers. A statistical model of defect dynamics during annealing accounts for these results, showing that the activation yield follows a logarithmic dependence on local vacancy concentration - extending over three decades for NV - and two for SiV -.enNitrogen-vacancy centers (NV-)Silicon-vacancy centers (SiV-)Diamond color centersIon implantationVacancy engineeringDefect activationjournal article