Compact virtual-source currentvoltage model for top-and back-gated graphene field-effect transistors

Abstract

This paper presents a compact model for the currentvoltage characteristics of graphene field-effect transistors (GFETs), which is based on an extension of the virtual-source model previously proposed for Si MOSFETs and is valid for both saturation and nonsaturation regions of device operation. This GFET virtual-source model provides a simple and intuitive understanding of carrier transport in GFETs, allowing extraction of the virtual-source injection velocity vVS, which is a physical parameter with great technological significance for short-channel graphene transistors. The derived IV characteristics account for the combined effects of the drainsource voltage VDS, the top-gate voltage VTGS, and the back-gate voltage VBGS. With only a small set of fitting parameters, the model shows excellent agreement with experimental data. It is also shown that the extracted virtual-source carrier injection velocity for graphene devices is much higher than in Si MOSFETs and state-of-the-art IIIV heterostructure FETs with similar gate length, demonstrating the great potential of GFETs for high-frequency applications. Comparison with experimental data for chemical-vapor-deposited GFETs from our group and epitaxial GFETs in the literature confirms the validity and flexibility of the model for a wide range of existing GFET devices. © 2010 IEEE.