Transport through the Interface between a Semiconducting Carbon Nanotube and a Metal Electrode

TL;DR

This paper presents a numerical analysis of tunnel conductance at the interface between semiconducting carbon nanotubes and metal electrodes, highlighting the effects of doping asymmetry, gate distance, and tunneling behavior, with results aligning with experimental data.

Contribution

It provides a detailed numerical model of the Schottky barrier in carbon nanotube transistors, emphasizing the impact of device geometry and doping on conductance and on--off ratios.

Findings

Asymmetry depends mainly on Fermi level and band gap differences.

Gate/nanotube distance significantly affects on--off ratios.

Transition from thermal activation to tunneling explains current behavior.

Abstract

We report a numerical study of the tunnel conductance through the Schottky barrier at the contact between a semiconducting carbon nanotube and a metal electrode. In a planar gate model the asymmetry between the p--doped and the n--doped region is shown to depend mainly on the difference between the electrode Fermi level and the band gap of carbon nanotubes. We quantitatively show how the gate/nanotube distance is important to get large on--off ratios. We explain the bend of the current versus gate voltage as the transition from a thermal--activation region to a tunneling region. A good agreement is obtained with experimental results for carbon nanotubes field--effect transistors.