High-Performance Carbon Nanotube Field-Effect Transistor With Tunable Polarities

TLDR

Carbon‑nanotube field‑effect transistors are Schottky‑barrier‑modulated devices whose performance improves with thinner gate oxides, yet this scaling also induces ambipolar behavior and higher drain leakage. The proposed device architecture permits aggressive scaling of oxide thickness and gate length while preserving the desired transistor characteristics. Using this design, the authors fabricated enhancement‑mode CNFETs that can be tuned to n‑ or p‑type unipolar operation, achieving excellent OFF‑state performance and a steep subthreshold swing of 63 mV/dec.

Abstract

State-of-the-art carbon nanotube field-effect transistors (CNFETs) behave as Schottky-barrier-modulated transistors. It is known that vertical scaling of the gate oxide significantly improves the performance of these devices. However, decreasing the oxide thickness also results in pronounced ambipolar transistor characteristics and increased drain leakage currents. Using a novel device concept, we have fabricated high-performance enhancement-mode CNFETs exhibiting n- or p-type unipolar behavior, tunable by electrostatic and/or chemical doping, with excellent OFF-state performance and a steep subthreshold swing (S=63 mV/dec). The device design allows for aggressive oxide thickness and gate-length scaling while maintaining the desired device characteristics.