Enhanced activation yield of nitrogen-vacancy and silicon-vacancy diamond color centers by proton and carbon irradiation

Abstract:

We 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 ⁻.

Authors: Stefano Lagomarsino, Nemanja Markešević, Zeeshan Rashid, Assegid Mengistu Flatae, Sven Mägdefessel, Santiago Hernández-Gómez, Giovanni Bianchini, Florian Sledz, Nicla Gelli, Lorenzo Giuntini, Mirko Massi, Silvio Sciortino, Chiara Corsi, Volker Cimalla, Peter Knittel, Michael Kunzer, Marco Bellini, Nicole Fabbri, Mario Agio

Publication location: Diamond and Related Materials

Date of publication: October 2025

D.O.I: https://doi.org/10.1016/j.diamond.2025.112632

How to cite this article: Stefano Lagomarsino, Nemanja Markešević, Zeeshan Rashid, Assegid Mengistu Flatae, Sven Mägdefessel, Santiago Hernández-Gómez, Giovanni Bianchini, Florian Sledz, Nicla Gelli, Lorenzo Giuntini, Mirko Massi, Silvio Sciortino, Chiara Corsi, Volker Cimalla, Peter Knittel, Michael Kunzer, Marco Bellini, Nicole Fabbri, Mario Agio, Enhanced activation yield of nitrogen-vacancy and silicon-vacancy diamond color centers by proton and carbon irradiation, Diamond and Related Materials, Volume 158, 2025, 112632, ISSN 0925-9635, https://doi.org/10.1016/j.diamond.2025.112632