Four-Probe Measurements of Carbon Nanotubes with Narrow Metal Contacts

TL;DR

This study demonstrates that electrons in single-wall carbon nanotubes can travel significant distances under narrow metal contacts, leading to deviations from classical circuit behavior in four-probe measurements.

Contribution

It reveals electron propagation under metal contacts and challenges standard Kirchhoff's rules in nanotube transport measurements.

Findings

Electrons propagate tens of nanometers under metal contacts.

Four-probe measurements show deviations from Kirchhoff's rules.

Current injection affects voltage at distant contacts.

Abstract

We find that electrons in single-wall carbon nanotubes may propagate substantial distances (tens of nanometers) under the metal contacts. We perform four-probe transport measurements of the nanotube conductance and observe significant deviations from the standard Kirchhoff's circuit rules. Most noticeably, injecting current between two neighboring contacts on one end of the nanotube, induces a non-zero voltage difference between two contacts on the other end.