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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]

Considering its high carrier mobility and high saturation velocity, a low-noise amplifier is thought of as being the most attractive analogue application of graphene field-effect transistors. The noise performance of graphene field-effect transistors at frequencies in the K-band remains unknown. In this work, the noise parameters of a graphene transistor are measured from 10 to 26 GHz and noise models are built with the data. The extrinsic minimum noise figure for a graphene transistor reached 1.5 dB, and the intrinsic minimum noise figure was as low as 0.8 dB at a frequency of 10 GHz, which were comparable with the results from tests on Si CMOS and started to approach those for GaAs and InP transistors. Considering the short development time, the current results are a significant step forward for graphene transistors and show their application potential in high-frequency electronics. [ABSTRACT FROM AUTHOR]

Low-noise amplifier is one of the most attractive applications of graphene transistors in the RF area. In this letter, a graphene amplifier MMIC is fabricated on the quasi-free-standing bilayer epitaxial graphene grown on SiC (0001) substrate. In order to realize both the high gain and low return loss, Au matching lines are designed as the input and output impedance match networks. The fabricated graphene amplifier MMIC shows a small-signal power gain of 3.4 dB at 14.3 GHz and a minimum noise figure of 6.2 dB. This letter is a significant step forward for graphene electronics in low-noise amplifier and demonstrates graphene’s potential in RF applications for future high-speed electronics. [ABSTRACT FROM PUBLISHER]

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]