Impact of near-contact barriers on the subthreshold slope of short-channel CNTFETs

Recent experimental investigations of sub-10nm carbon nanotube (CNT) field-effect transistors (FETs) promote CNT based 1D-electronics as a candidate for a future aggressively scaled transistor technology. However, the ballistic transport within the 1D semiconducting CNT channel is largely determined by charge injection from the contacts rendering reliable theoretical predictions of the transistor performance difficult. Based on a simplified heterojunction like contact model, we demonstrate by solving the Schrödinger-Poisson equations that aggressive scaling will rely on a careful balance between two components of the injected charges, one responsible for the formation of near-contact barriers and the other carrying the current. Excellent electrostatic gate control (e.g. employing thin gate oxides) may then enable transistor scaling until the onset of direct source-drain tunneling.