Electric field effects in STM imaging

TL;DR

This paper extends the Tersoff-Hamann theory to include electric field effects in STM imaging, using first-principles calculations to better match experimental observations of surface features.

Contribution

It introduces a high voltage extension of STM theory that accounts for electric fields without adjustable parameters, improving the accuracy of surface imaging simulations.

Findings

Electric field enhances surface corrugation in STM images.

Theoretical images agree well with experimental data.

Method applies to high voltage STM imaging scenarios.

Abstract

We present a high voltage extension of the Tersoff-Hamann theory of STM images, which includes the effect of the electric field between the tip and the sample. The theoretical model is based on first principles electronic structure calculations and has no adjustable parameters. We use the method to calculate theoretical STM images of the monohydrate Si(100)-H(2$\times$1) surface with missing hydrogen defects at $- 2$~V and find an enhanced corrugation due to the electric field, in good agreement with experimental images.