Double contacts for improved performance of graphene transistors

A new double-contact geometry for graphene devices is studied and compared to traditional top contacts. Double contacts consist of metal below and above the graphene in a sandwich-type configuration. Four-probe structures were tested for both single-layer [chemical-vapor-deposition (CVD)-grown] graphene and bilayer (mechanically exfoliated) graphene, with both showing a decrease in contact resistance of at least 40% and an increase in transconductance greater than 20%. CVD-grown single-layer graphene transistors exhibited contact resistance as low as 260 Ωμm, with an average of 320 Ωμm. This new geometry can help minimize the impact of contacts on graphene device performance.