Fermi-level alignment at metal-carbon nanotube interfaces: application to scanning tunneling spectroscopy

TL;DR

This paper investigates how charge transfer at metal-carbon nanotube interfaces affects the Fermi-level alignment, using electrostatic modeling to explain scanning tunneling spectroscopy observations and implications for nanotube transistors.

Contribution

The study provides a detailed electrostatic model explaining Fermi-level shifts at metal-carbon nanotube interfaces and discusses its relevance to nanotube transistor contact behavior.

Findings

Charge transfer induces local electrostatic potential changes.

Fermi-level shifts observed in STS are explained by the model.

Fermi-level alignment varies with contact resistance in nanotube transistors.

Abstract

At any metal-carbon nanotube interface there is charge transfer and the induced interfacial field determines the position of the carbon nanotube band structure relative to the metal Fermi-level. In the case of a single-wall carbon nanotube (SWNT) supported on a gold substrate, we show that the charge transfers induce a local electrostatic potential perturbation which gives rise to the observed Fermi-level shift in scanning tunneling spectroscopy (STS) measurements. We also discuss the relevance of this study to recent experiments on carbon nanotube transistors and argue that the Fermi-level alignment will be different for carbon nanotube transistors with low resistance and high resistance contacts.