Nanotube-Metal Junctions: 2- and 3- Terminal Electrical Transport

TL;DR

This study uses first-principles calculations to analyze electron transmission in nanotube-metal junctions, revealing the physical limits of conduction and the influence of metal material on transport properties.

Contribution

It provides a detailed theoretical analysis of 2- and 3-terminal nanotube-metal junctions, clarifying the impact of contact area and metal type on electrical conductance.

Findings

Metallic tubes approach ideal conductance with large contact area

Transmission depends strongly on metal material in three-terminal setups

Pd electrodes nearly perfect transmission but suppress straight tube transport

Abstract

We address the quality of electrical contact between carbon nanotubes and metallic electrodes by performing first-principles calculations for the electron transmission through ideal 2- and 3-terminal junctions, thus revealing the physical limit of tube-metal conduction. The structural model constructed involves surrounding the tube by the metal atoms of the electrode as in most experiments; we consider metallic (5,5) and n-doped semiconducting (10,0) tubes surrounded by Au or Pd. In the case of metallic tubes, the contact conductance is shown to approach the ideal 4e^2/h in the limit of large contact area. For three-terminals, the division of flux among the different transmission channels depends strongly on the metal material. A Pd electrode has nearly perfect tube-electrode transmission and therefore turns off the straight transport along the tube. Our results are in good agreement with some recent experimental reports and clarify a fundamental discrepancy between theory and experiment.