Chemical Vapour Deposition Graphene Radio-Frequency Field-Effect Transistors

We report the dc and rf performance of graphene rf field-effect transistors, where the graphene films are grown on copper by using the chemical vapour deposition (CVD) method and transferred to SiO₂/Si substrates. Composite materials, benzocyclobutene and atomic layer deposition Al₂O₃ are used as the gate dielectrics. The observation of n− and p-type transitions verifies the ambipolar characteristics in the graphene layers. While the intrinsic carrier mobility of CVD graphene is extracted to be 1200 cm²/V⋅s, the parasitic series resistances are demonstrated to have a serious impact on device performance. With a gate length of 1 µm and an extrinsic transconductance of 72 mS/mm, a cutoff frequency of 6.6 GHz and a maximum oscillation frequency of 8.8 GHz are measured for the transistors, illustrating the potential of the CVD graphene for rf applications.