A phantom force induced by the tunneling current, characterized on Si(111)

TL;DR

This paper investigates how tunneling currents can induce a phantom force during atomic force measurements, especially on low-conductance samples like Si(111), affecting the interpretation of atomic-scale force data.

Contribution

It provides experimental and theoretical insights into the impact of tunneling current on measured forces, highlighting a previously underappreciated effect in atomic-scale measurements.

Findings

Tunneling current can induce a significant phantom force on Si(111) surfaces.

The effect is pronounced in low-conductance samples and influences Kelvin probe measurements.

The study combines experimental data with calculations to elucidate this phenomenon.

Abstract

Simultaneous measurements of tunneling currents and atomic forces on surfaces and adsorbates provide new insights into the electronic and structural properties of matter on the atomic scale. We report on experimental observations and calculations of a strong impact the tunneling current can have on the measured force, which arises when the resistivity of the sample cannot be neglected. We present a study on Si(111)-7\times7 with various doping levels, but this effect is expected to occur on other low-conductance samples like adsorbed molecules, and is likely to strongly affect Kelvin probe measurements on the atomic scale.