Towards Optically Coupled Scanning Tunneling Microscopy of NV-Centers in Diamond

Despite tremendous interest in diamond’s nitrogen-vacancy (NV) centers, there have as yet been no atomic-scale investigations of the structural and electronic characteristics of these defects. While the ideal technique for such local measurements is scanning tunneling microscopy (STM), diamond’s insulating nature has thus far prevented study of NVs by STM. In this talk, we show how over the past year, we first developed a technique for transferring monolayer graphene onto clean NV-enriched diamond crystals. The conducting graphene makes STM on diamond possible, while still allowing for electronic states from subsurface defects to be detected. We’ve then found defects with peaks in the electronic density of states (DOS) consistent with NV^- and also have manipulated the individual defect charge states using the electric field at our tip-sample junction. We will further discuss our more recent progress in coupling optical photoluminescence (PL) measurements with STM to correlate the defects we see topographically and in the local electronic DOS with PL signals. This combined optical STM approach strengthens our identification of the defects we see as NVs and paves the way toward a robust technique for atomic-scale visualization and manipulation of NV-centers in diamond.