Molecular Nanosensors based on the Inter-sheet Tunneling Effect of a Bilayer Graphene

This paper presents the design, fabrication, and characterization of a novel high-performance molecule sensor using the inter-sheet tunneling effect of a bilayer graphene. Nanosensors for ethanol molecules have been fabricated based on mechanical exfoliation and e-beam lithography for demonstrating the feasibility. Experiments reveled that by making electric contacts to different sheets of a bilayer graphene, inter-sheet effects can be exposed. As a result, the "inter-layer" sensor has a much higher (a typical result showed more than 8 times higher) sensitivity than that of an "intra-layer" sensor, in which the electric contacts are placed on the same layer. The adoption of the inter-sheet effects remarkably enriched the applicable transduction mechanisms. These include the enhanced edge effects due to the extra sides, inter-sheet tunneling due to the spacing change caused by molecule adsorption/desorption, force/displacement, pressure, surface tension, and heating, and potentially inter-sheet doping due to the open step.