Effect of Gate Dielectric on Ballistic Transport of Cylindrical Carbon Nanotube MOSFET

Abstract

Carbon NanoTube (CNT) channel promises near ballistic transport and is examined extensively for potential application in next-generation Nano-scale transistor. Cylindrical gate-all-around CNT field effect transistor (CNTFET) with semiconducting CNT S/D contacts and Schottky barrier CNTFET (SBCNTFET) are modeled numerically based on self-consistent solution of Poisson-Schrödinger equation with open boundary conditions within Non-Equilibrium Green’s Function formalism considering coaxial symmetry. The effect of dielectric constant (κ) and physical thickness of gate dielectric on transport characteristics of CNTFET and SBCNTFET are examined in this work. Gate capacitance, carrier injection velocity, current and therefore speed increases significantly with the inclusion of high κ dielectric and decrease in thickness. SBCNTFET also shows better performance with thin high κ dielectric layer. High trans-conductance and much lower Sub-threshold swing is visible with the inclusion of high κ gate stack.