Contact resistivity and current flow path at metal/graphene contact

The contact properties between metal and graphene were examined. The electrical measurement on a multiprobe device with different contact areas revealed that the current flow preferentially entered graphene at the edge of the contact metal. The analysis using the cross-bridge Kelvin (CBK) structure suggested that a transition from the edge conduction to area conduction occurred for a contact length shorter than the transfer length of $∼1μm$⁠. The contact resistivity for Ni was measured as $∼5×10−6Ωcm2$ using the CBK. A simple calculation suggests that a contact resistivity less than $10−9Ωcm2$ is required for miniaturized graphene field effect transistors.