A SPICE Compact Model for Ambipolar 2-D-Material FETs Aiming at Circuit Design

We report a charge-based analytic and explicit compact model for field-effect transistors (FETs) based on 2-D materials (2DMs), for the simulation of 2DM-based analog and digital circuits. The device electrostatics is handled by invoking 2-D density of states and Fermi-Dirac statistics that are later combined with the Lambert-W function and Halley's correction to eventually obtain explicit expressions for the electron and hole charges, which are exploited in the calculation of drift-diffusion currents for both carriers. Furthermore, the charge model is extended to obtain characteristics of 2DM-based negative capacitance FETs. The model is benchmarked against experimental MoS₂ FET measurements and experimental ambipolar characteristics of narrowband-gap materials, such as black phosphorus. Its soundness for SPICE circuit-level simulations is also demonstrated.