Single carrier capture at color centers with cross section approaching 1 µm²

Understanding the generation, diffusion, and capture of charge carriers in semiconductors is of fundamental and technological importance, but the ensemble measurement techniques typically in use tend to obscure microscopic processes otherwise relevant to grasp key features of the system dynamics. Here, we combine widefield illumination and resonant optical excitation to examine the capture of photogenerated holes by negatively charged nitrogen vacancy (NV^-) centers in diamond under cryogenic conditions. Single-shot charge readout of individual NVs allows us to monitor carrier capture events individually, a capability we then exploit to derive the distribution functions governing the statistics of the capture process. We calculate hole capture cross sections for NV^- approaching 1 µm², a result we attribute to the formation of transient Rydberg states. These values should be seen as a lower limit stemming from bound exciton dissociation in the presence of coexisting defects, a notion we demonstrate through observations under varying, optically initialized environments.