Highly reproducible low temperature scanning tunnelling microscopy and spectroscopy with in situ prepared tips

TL;DR

This paper introduces a simple in situ tip preparation method for low temperature STM that enhances tip stability and measurement reproducibility without extra processing steps, demonstrated on epitaxial graphene.

Contribution

The authors present a novel in situ tip preparation technique that improves STM tip stability and reproducibility at low temperatures without additional preparation methods.

Findings

In situ prepared tips increase stability of STM images.

Reproducibility of spectroscopy measurements is improved.

Method is effective on epitaxial graphene surfaces.

Abstract

An in situ tip preparation procedure compatible with ultra-low temperature and high magnetic field scanning tunneling microscopes is presented. This procedure does not require additional preparation techniques such as thermal annealing or ion milling. It relies on the local electric-field-induced deposition of material from the tip onto the studied surface. Subsequently, repeated indentations are performed onto the sputtered cluster to mechanically anneal the tip apex and thus to ensure the stability of the tip. The efficiency of this method is confirmed by comparing the topography and spectroscopy data acquired with either unprepared or in situ prepared tips on epitaxial graphene grown on Ru (0001). We demonstrate that the use of in situ prepared tips increases the stability of the scanning tunneling images and the reproducibility of the spectroscopic measurements.