Carbon fibre tips for scanning probe microscopy based on quartz tuning fork force sensors

TL;DR

This paper introduces a method to fabricate and characterize carbon fibre tips for combined scanning tunnelling and force microscopy using quartz tuning fork sensors, highlighting their high sensitivity, robustness, and high-resolution imaging capabilities.

Contribution

It presents a reproducible electrochemical fabrication process for sub-100 nm carbon fibre tips optimized for high-resolution, combined microscopy techniques.

Findings

Carbon fibre tips minimally impact tuning fork dynamics.

Tips exhibit high electrical conductivity and oxidation resistance.

Reproducible fabrication yields high-resolution imaging.

Abstract

We report the fabrication and the characterization of carbon fibre tips for their use in combined scanning tunnelling and force microscopy based on piezoelectric quartz tuning fork force sensors. We find that the use of carbon fibre tips results in a minimum impact on the dynamics of quartz tuning fork force sensors yielding a high quality factor and consequently a high force gradient sensitivity. This high force sensitivity in combination with high electrical conductivity and oxidation resistance of carbon fibre tips make them very convenient for combined and simultaneous scanning tunnelling microscopy and atomic force microscopy measurements. Interestingly, these tips are quite robust against occasionally occurring tip crashes. An electrochemical fabrication procedure to etch the tips is presented that produces a sub-100 nm apex radius in a reproducible way which can yield high resolution images.