High-Percentage Success Method for Preparing and Pre-Evaluating Tungsten Tips for Atomic-Resolution Scanning Tunneling Microscopy

TL;DR

This paper introduces a custom double-lamella electrochemical etching method for tungsten STM tips, which reliably produces larger cone angles and higher-quality atomically resolved images compared to conventional techniques.

Contribution

The paper presents a novel double-lamella etching technique that improves the reliability and quality of tungsten tips for atomic-resolution STM imaging.

Findings

Larger cone angles correlate with higher image quality.

The custom etching method produces more reliable high-quality tips.

Tips etched with the new method yield clearer atomic-resolution images.

Abstract

A custom double-lamella method is presented for electrochemically etching tungsten wire for use as tips in scanning tunneling microscopy (STM). For comparison, tips were also manufactured in-house using numerous conventional methods and examined using an optical microscope. Both sets of tips were used to obtain STM images of highly-oriented pyrolytic graphite, the quality of which varied. The clarity of the STM images was found to be correlated to the optically-measured cone angle of the STM tip, with larger cone angles consistently producing atomically resolved images. The custom etching procedure described allows one to create larger cone angles and consequently proved superior in reliably producing high-quality tips.