Assessment of High-Frequency Performance Limits of Graphene Field-Effect Transistors

TL;DR

This study uses quantum simulations to explore the high-frequency limits of graphene FETs at very small channel lengths, revealing potential for THz operation despite tunneling effects.

Contribution

It provides a detailed analysis of the performance limits of graphene FETs at 20nm channel length using self-consistent quantum simulations, highlighting the impact of tunneling and parasitic capacitances.

Findings

Good transconductance and on-off ratio achievable at 20nm

Intrinsic cut-off frequency remains in the THz range

Thin gate insulators improve performance amidst parasitic effects

Abstract

High frequency performance limits of graphene field-effect transistors (FETs) down to a channel length of 20nm are examined by using self-consistent quantum simulations. The results indicate that although Klein band-to-band tunneling is significant for sub-100nm graphene FET, it is possible to achieve a good transconductance and ballistic on-off ratio larger than 3 even at a channel length of 20nm. At a channel length of 20nm, the intrinsic cut-off frequency remains at a couple of THz for various gate insulator thickness values, but a thin gate insulator is necessary for a good transconductance and smaller degradation of cut-off frequency in the presence of parasitic capacitance. The intrinsic cut-off frequency is close to the LC characteristic frequency set by graphene kinetic inductance and quantum capacitance, which is about 100GHz \cdot {\mu}m divided by the gate length.