Multifinger Embedded T-Shaped Gate Graphene RF Transistors With High $f_{\rm MAX}/f_{T}$ Ratio

Gate resistance plays a key role in determining the maximum oscillation frequency (fMAX) of all radio frequency transistors. This letter presents a new graphene device structure having multiple-finger T-shaped gates embedded in the substrate. The structure possesses several advantages over conventional top gate structures, including low gate resistance, low parasitic capacitance, scalable gate dielectric, and simple interconnect wiring. With 1 V drain bias, fMAX up to 20 GHz, and ~25%-43% higher than the current gain cutoff frequency (fT), is achieved from devices with a channel length down to 250 nm.