The influence of grain boundaries and mechanical deformations in graphene film on the electric charge transport was investigated at nanoscale with conductive atomic force microcopy. Large area monolayer graphene samples were prepared by the chemical vapor deposition technique. Field emission scanning electron microscopy confirmed the formation of grain boundaries and the presence of wrinkles. The presence of the D-band in the Raman spectrum also indicated the existence of sharp defects such as grain boundaries. Extremely low conductivity was found at the grain boundaries and the wrinkled surface was also more resistive in comparison to the plain graphene surface. Many samples were experimented with, to justify the present findings, by selecting different areas on the graphene surface. Uniform conductivity was found on grain boundary and wrinkle free graphene surfaces. Channels of various lengths were made, using local anodic oxidation, to confine the charge carrier to the smallest dimensions and better confirm the alteration in current due to grain boundaries and wrinkles.

Nanoscale Investigation of Charge Transport at the Grain Boundaries and Wrinkles in Graphene Film. M.Ahmad, H.An, Y.S.Kim, J.H.Lee, J.Jung, S.H.Chun, Y.Seo: Nanotechnology, 2012, 23[28], 285705