Design of circuit compatible model for carbon nanotube field effect transistor

Abstract

Device scaling drives technological advancements, but CMOS technology faces imminent limitations. To extend its functionality and explore new device paradigms, alternative nanoscale devices are being investigated under the ‘More than Moore’ approach. This trend integrates functionalities that do not scale according to Moore’s law. Emerging devices such as FinFET, Tunnel FET, Junction-less FET, Tri-gate, Si-nanowire MOSFETs, Carbon-based FETs, and Spin-FETs are being explored. To incorporate these devices into circuit simulations, equivalent models must be developed since conventional models cannot accurately represent nanoscale behavior. This study presents a compact model for Carbon Nanotube Field-Effect Transistors (CNTFETs) for circuit simulations. Carbon nanotubes (CNTs) have gained significant academic interest due to their unique electrical properties, including ballistic and non-ballistic electron transport. CNTFETs offer advantages such as mechanical strength, flexibility, low power consumption, thermal stability, and high circuit density. Initially, the OPV molecule—considered part of a graphene sheet—will be analyzed before extending the model to CNTs, which are essentially rolled-up graphene sheets. Current CNT transistor modeling techniques primarily use MATLAB to simulate transport mechanisms. These models rely on ideal numerical equations, often failing to account for non-ballistic transport effects, resulting in discrepancies between simulations and real-world performance. The primary goal of CNT transistor modeling is to predict circuit performance before fabrication, ensuring simulation results closely reflect actual device behavior. This work develops a simple compact model that accurately reproduces CNTFET I–V characteristics using the Non-Equilibrium Green’s Function (NEGF) approach. By leveraging NEGF, the model bypasses complex density function tight-binding calculations, facilitating efficient I–V characterization and improving the integration of CNTFETs in circuit simulations.

Keywords: Carbon Nanotube Field-Effect Transistor (CNTFET), Compact Modeling, Non-Equilibrium Green’s Function (NEGF), Circuit Simulation, Nanoelectronic Devices