Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments

TL;DR

This paper introduces a method to fabricate and characterize carbon-fiber tips for combined scanning tunneling and force microscopy, demonstrating their use in forming and studying single-molecule junctions with octanethiol.

Contribution

It presents a reproducible electrochemical fabrication process for sub-100-nm carbon tips and explores their application in molecular electronics experiments.

Findings

Reproducible sub-100-nm apex carbon tips fabricated.

Observation of conductance plateaus indicating molecular junction formation.

Successful measurement of electron transport through single-molecule junctions.

Abstract

We fabricate and characterize carbon-fiber tips for their use in combined scanning tunneling and force microscopy based on piezoelectric quartz tuning fork force sensors. An electrochemical fabrication procedure to etch the tips is used to yield reproducible sub-100-nm apex. We also study electron transport through single-molecule junctions formed by a single octanethiol molecule bonded by the thiol anchoring group to a gold electrode and linked to a carbon tip by the methyl group. We observe the presence of conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction.