Equilibrium charge state of NV centers in diamond

We investigated charge states of nitrogen vacancy (NV) centers in diamond single crystals. The charge states were evaluated using concentrations of both negatively charged (NV−) and neutral-state (NV0) NV centers. This study specifically examines diamond crystals containing mainly neutral substitutional nitrogen (N0s), NV− centers, and NV0 centers. Results show that the charged states of NV centers evaluated for this study depended on concentrations of both neutral substitutional nitrogen (N0s) and NVT centers, which is a sum of [NV−] and [NV0]. The NV centers were fully negatively charged when the ratio of [NVT] to [N0s] was 1%–20% in our diamond crystals. When [NVT]/[N0s] is larger than 20%–30%, NV0 centers appeared gradually. The concentration ratio between NV− centers and NV0 centers was described using an equilibrium equation.