Abstract
In this letter, we report on the performance of graphene field-effect transistors (GFETs) in which the extrinsic transit frequency (f(T)) and maximum frequency of oscillation (f(max)) showed improved scaling behavior with respect to the gate length (L-g). This improvement was achieved by the use of high-quality graphene in combination with successful optimization of the GFET technology, where extreme low source/drain contact resistances were obtained together with reduced parasitic pad capacitances. GFETs with gate lengths ranging from 0.5 mu m to 2 mu m have been characterized, and extrinsic f(T) and f(max) frequencies of up to 34 and 37 GHz, respectively, were obtained for GFETs with the shortest gate lengths. Simulations based on a small-signal equivalent circuit model are in good agreement with the measured data. Extrapolation predicts extrinsic f(T) and fmax values of approximately 100 GHz at L-g = 50 nm. Further optimization of the GFET technology enables f(max) values above 100 GHz, which is suitable for many millimeter wave applications.