A Compact Current–Voltage Model for 2-D-Semiconductor-Based Lateral Homo-/Hetero-Junction Tunnel-FETs

Abstract

A fully analytical surface potential and current–voltage model is presented for the first time for both lateral homojunction (HMJ) and heterojunction (HTJ) tunneling-field-effect transistors (TFETs) based on 2-D semiconducting channel materials. The dynamic gate-modulated electrostatic potential at the source/channel tunneling junction is suitably captured by solving a quasi-2-D Poisson’s equation in both source and channel. Subsequently, the band-to-band tunneling current is accurately derived starting from the Landauer’s equation by integrating over all possible carrier energies (or wave-vectors) over which tunneling is possible. The model employs Fermi–Dirac statistics in both the degenerate source and drain to compute the surface potential and net current, which yields more physical results than the commonly employed Boltzmann statistics. Its use in Landauer’s approach for evaluating the net ON-current leads to an analytical model of the TFET, which physically guarantees zero drain current at zero drain–source bias. Input and output characteristics for both HMJ and HTJ TFETs are computed and compared against rigorous nonequilibrium Green’s function (NEGF) simulations for different device parameters to prove the veracity of the model, and the match has been found to be excellent up to ultrashort channel length of 5 nm.