An Enhanced Verilog-A Model for Graphene Field-Effect Transistors Using Variable Fermi Velocity

This paper presents a novel Verilog-A model for the Fermi velocity in Graphene Field-Effect Transistors (GFETs). The Fermi velocity is an important parameter associated with the energy spectrum of the delocalized bonds in graphene which impact the performance of a GFET. Unlike existing GFET models where the Fermi velocity is assumed to have a constant value, the proposed model considers carrier concentrations in the channel and gate dielectrics to create a closed-form solution for the Fermi velocity, a parameter previously demonstrated to vary based on these two factors. The proposed mathematical model is then adapted to Verilog-A for interfacing with computer-aided design (CAD) circuit simulators. To demonstrate the accuracy of the proposed model, the simulation results are compared to measured drain–source currents obtained from various GFET devices (including GFETs measured by authors). The measured results show good agreement with the values predicted using the proposed model (<±1%), demonstrating the superior accuracy of the model compared to other published Verilog-A-based models, especially around the Dirac point.