RF performance projections for 2D graphene transistors: Role of parasitics at the ballistic transport limit

Graphene is a two-dimensional zero bandgap material with carbon atoms arranged in a honeycomb lattice. Although 2D monolayer graphene lacks a bandgap, it still shows promising potential for applications in high frequency analog devices that do not require a high on/off ratio as demanded by digital logic. A cutoff frequency, fτ , as high as 170GHz is achieved in a 90 nm channel length Graphene Field-Effect-Transistor (GFET) with back-gated structure. Projected fτ = 300GHz is reported for channel length Lch = 140nm top-gated structure. The motivation of this work is to explore the potential of high frequency performance of GFETs, and to elucidate the major factors that limit their performance. Our model captures the degradation of intrinsic performance due to parasitics, and the effect of metal-graphene (M-G) contacts as: (1) contact doping effect due to M-G work function difference, and (2) DOS broadening by M-G coupling and metal-induced states in the channel.