Simultaneous current-, force- and work function measurement with atomic resolution

TL;DR

This paper introduces a method combining STM and AFM to measure local work function, forces, and tunneling current simultaneously at atomic resolution, providing detailed surface electronic and force information.

Contribution

It presents a novel technique for concurrent atomic-scale measurement of work function, forces, and tunneling current using a combined STM/AFM system.

Findings

Atomic resolution work function maps of silicon surface

Correlation between work function, current, and force measurements

Demonstration of simultaneous measurement capability

Abstract

The local work function of a surface determines the spatial decay of the charge density at the Fermi level normal to the surface. Here, we present a method that enables simultaneous measurements of local work function and tip-sample forces. A combined dynamic scanning tunneling microscope and atomic force microscope is used to measure the tunneling current between an oscillating tip and the sample in real time as a function of the cantilever's deflection. Atomically resolved work function measurements on a silicon (111)-($7\times 7$) surface are presented and related to concurrently recorded tunneling current- and force- measurements.