Local conductance mapping of water-intercalated graphene on mica

Abstract

We report that the conductance of graphene is influenced by intercalated water layers using current sensing atomic force microscopy (AFM). We obtained a confined water layer between chemical vapor deposition graphene and mica by transferring graphene onto mica in a liquid water bath. Atomic force microscopy topographic images confirm high coverage by a single water layer, and scanning tunneling microscopy (STM) verifies a clean surface without contamination by measuring the honeycomb lattice structure of the graphene. We show that the surface conductance is perturbed by the presence of a water layer between the graphene and mica, which is not found in the STM topographic image. We found that the graphene on the edge and at pinholes of the water layer exhibits lower conductance, compared with that of graphene on the water terrace. We attribute the perturbation of conductance to structural defects from the water film and a variation of interaction between the edge of the water and graphene. Published by AIP Publishing.