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

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. PACS, 07.79.-v, scanning probe microscopes and components, 68.37.Ef, scanning tunneling microscopy (including chemistry induced with STM), 73.63.-b, electronic transport in nanoscale materials and structures, 85.65. + h, molecular electronic devices, 73.40.-c, electronic transport in interface structures. © 2012 Rubio-Bollinger et al.