RF model of a back-gated graphene field effect transistor

This paper presents the RF characterization and modeling of a back-gated graphene field effect transistor (GFET) embedded in a coplanar waveguide (CPW). The electromagnetic model (EM) of the graphene structure includes both channel and metal/graphene contact resistances as well as all involved parasitic capacitances. The S-parameters of the resulting structures have been measured at room temperature in the frequency range from 10 MHz to 67 GHz for back-gate voltages up to 37 V. Measurements show a roughly back-gate independent contact resistance (~ 900 Ωμm) and a highly rise in channel resistance from 20 Ω to 2.34 kΩ when increasing the back-gate voltage from 0 V to 37 V (Dirac point). Moreover, the associated capacitance decreases from 4.1 fF to 0.7 fF for the same voltage range. The simulation results of the electromagnetic model from the CPW together with the graphene structure are in reasonable well agreement with our measurements.