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Analog applications attract increasing interest for graphene field-effect transistors (GFETs). GFET with a cutoff frequency of up to 427 GHz has been reported; however, the device suffered from the large parasitic parameters and poor drain current saturation, which made their maximum oscillation frequency lower than the cutoff frequency. In this letter, quasi-free-standing bilayer graphene transistors with a gate length of 60 nm and ultra-thin gate dielectric are fabricated by an improved, self-aligned, process. Good gate coupling is achieved, and parasitic parameters are suppressed to a significant extent. The as-measured extrinsic cutoff frequency reaches 70 GHz and the maximum oscillation frequency reaches 120 GHz, which are the highest extrinsic frequencies reported for graphene transistors to date. Our results show the application potential of graphene RF devices in future high-speed electronic systems. [ABSTRACT FROM AUTHOR]

Quasi-free-standing epitaxialgraphenegrown on wide band gap semiconductorSiC demonstrates high carrier mobility and good material uniformity, which make it promising for graphene-based electronic devices. In this work, quasi-free-standing bilayer epitaxialgraphene is prepared and its transistors with gate lengths of 100 nm and 200 nm are fabricated and characterized. The 100 nm gate length graphenetransistor shows improved DC and RF performances including a maximum current density Ids of 4.2 A/mm, and a peak transconductance gm of 2880 mS/mm. Intrinsic current-gain cutoff frequency fT of 407 GHz is obtained. The exciting DC and RF performances obtained in the quasi-free-standing bilayer epitaxialgraphenetransistor show the great application potential of this material system. [ABSTRACT FROM AUTHOR]