Theoretical comparison of 3C-SiC and Si nanowire FETs in ballistic and diffusiveregimes

Abstract

Silicon carbide (SiC) nanowires (NWs) could combine the properties of one-dimensional(1D) structures with those of a wide band gap semiconductor. For this reason, we solvedself-consistently the Poisson equation with both the quantum Non-Equilibrium GreenFunction Formalism (NEGF) and the classical drift–diffusion model in order tomodel and compare 3C-SiC and Si NW Field Effect Transistors (FETs) operatingin ballistic and diffusive regimes. As a general conclusion from our calculationsin the ballistic regime, Si and SiC NW FETs have almost the same electricalbehavior. They show the same subthreshold slope and have similar on-current(ION/IOFF (SiC) ∼81% ION/IOFF (Si) in the case of a 4 nm NW cross-section side). The drift–diffusion model predicts a betterperformance for SiC NW FETs. More specifically, SiC devices have a lower subthreshold slope(∼85% for a Si device with 200 nm channel length) than Si devices as the FET channel lengthincreases (from 200 to 750 nm), and as in case of ballistic regime SiC devices have a slightlysmaller on-current.