Conductive Atomic Force Microscopy of Chemically Synthesized Graphene Oxide and Interlayer Conduction

Graphene oxide, a chemically modified graphene, has been attracting wide attention because of promising adaptability to a wide variety of applications. However, the properties of graphene oxide itself are not known well. Using a conductive cantilever, we observed a current image of graphene oxide nanosheets of various thicknesses. Current-voltage characteristics were found to reflect the local conductivity normal to the nanosheets. Under high electric fields, the conduction was well described in terms of Poole-Frenkel emission mechanism. The fitting of I-V curves to the Poole-Frenkel model provides information on dielectric properties, and the relative permittivity of graphene oxide was found to be 4.8 +/- 0.8.