Optically enhanced dissociation of divacancies in diamond

Nitrogen vacancy (NV) centers in diamonds are one of the promising examples of solid-state spin defects, with remarkable applications in quantum sensing and optics. While ion implantation with thermal annealing is extensively employed to generate NV centers in diamonds, the detrimental formation of divacancy (VV) centers degrades the resulting spin and optical properties by introducing a source of decoherence. As designing an annealing time and temperature progression for the targeted removal of VV centers is challenging, in this project, we demonstrate that the optical excitation of the VV centers can be an additional method to mediate its dissociation. Using first-principles simulations, we predict that the binding energy of VV centers is reduced by 1.7 eV due to the excitation of electrons from the VV-related defect states. Thus, a reduced annealing temperature may be sufficient to target specifically the removal of VV centers, without activating the dissociation of any other defect complexes. With experimental validation, we will provide a quantitative understanding and practical process of eliminating VV centers, which can improve the engineering of quantum devices.