Contact resistivity and current flow path at metal/graphene contact

TL;DR

This study investigates the contact resistivity and current flow paths at metal/graphene interfaces, revealing edge-dominant conduction and providing measurements crucial for miniaturized graphene transistors.

Contribution

It introduces a detailed analysis of current flow transition from edge to area conduction and measures contact resistivity using the cross-bridge Kelvin structure.

Findings

Current preferentially enters graphene at the contact edge.

Transition from edge to area conduction occurs at contact lengths shorter than ~1 micron.

Measured contact resistivity for Ni is approximately 5×10⁻⁶ Ohm·cm².

Abstract

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 structure (CBK) suggested that a transition from the edge conduction to area conduction occurred for a contact length shorter than the transfer length of ~1 micron. The contact resistivity for Ni was measured as ~5*10-6 Ohmcm2 using the CBK. A simple calculation suggests that a contact resistivity less than 10-9 Ohmcm2 is required for miniaturized graphene field effect transistors.