Precisely Controllable Generation and Characterization of Graphene Nanogaps

Electrode pairs with sub-3 nm nanogaps are essential for single-molecule devices. However, previously reported nanogap fabrication techniques are stochastically driven and often lead to nanogaps with broad resistance distributions. Here, we present a deterministic method for the precise generation of single-layer graphene nanogaps by controlling the electric breakdown process. Using autoranging source-measure hardware and adopting different control logics before and after breakdown, the gap generation process could be well-controlled. About 80% of devices fall within the same order of magnitude in nanogap resistance, which can be tuned by the termination parameter. Moreover, the SLG nanogaps are directly visualized on Si₃N₄ membrane windows by using transmission electron microscopy. This work establishes a robust approach for controlled SLG nanogap fabrication with sub-3 nm separations, paving the way toward the high yield of single-molecule junctions and related solid-state devices.