High-Gain Graphene Transistors with a Thin AlOx Top-Gate Oxide.

The high-frequency performance of transistors is usually assessed by speed and gain figures of merit, such as the maximum oscillation frequency f , cutoff frequency f , ratio f /f , forward transmission coefficient S , and open-circuit voltage gain A . All these figures of merit must be as large as possible for transistors to be useful in practical electronics applications. Here we demonstrate high-performance graphene field-effect transistors (GFETs) with a thin AlOx gate dielectric which outperform previous state-of-the-art GFETs: we obtained f /f  > 3, A  > 30 dB, and S  = 12.5 dB (at 10 MHz and depending on the transistor geometry) from S-parameter measurements. A dc characterization of GFETs in ambient conditions reveals good current saturation and relatively large transconductance ~600 S/m. The realized GFETs offer the prospect of using graphene in a much wider range of electronic applications which require substantial gain.