Photoelectric Imaging of the Optically Inactive Charge State of Silicon-Vacancy Defects in Diamond

The investigation of optically active point defects in wide-bandgap semiconductors is driven by the development of solid-state quantum technologies. Such atom-like defects are used for the realization of quantum registers and quantum sensors. Reproducible engineering of even well-established defects with predictable properties remains challenging, as the local environment and complex charge dynamics limit their performance and applicability. Furthermore, not all defects are optically accessible, which hinders our ability to study them. Here, we use the photoelectric detection technique to study switching and control of desired double and single charge states of silicon vacancy (SiV) defect in diamond. We demonstrate the first direct imaging of the dark charge state of SiV, which cannot be addressed by optical methods or electron paramagnetic resonance. We discuss a model for SiV charge state conversion involving proximal substitutional nitrogen defects. These findings are important for the charge state control of the entire family of group-IV defects in diamond.