Versatile scanning tunneling microscopy with 120ps time resolution

TL;DR

This paper presents a versatile ultra-high vacuum scanning tunneling microscope capable of 120 ps time resolution, enabling dynamic measurements of local electronic properties with atomic spatial resolution.

Contribution

The development of a fully compatible STM with ultra-high vacuum, high-frequency cabling, and 120 ps time resolution for dynamic electronic measurements.

Findings

Achieved 120 ps time resolution using nonlinear I(V) characteristics.

Demonstrated atomic resolution imaging in pulse mode.

Detected 50 pA tunneling current changes at 120 ps.

Abstract

We describe a fully ultra-high vacuum compatible scanning tunneling microscope (STM) optimized for radio-frequency signals. It includes in-situ exchangeable tips adapted to high frequency cabling and a standard sample holder, which offer access to the whole range of samples typically investigated by STM. We demonstrate a time resolution of 120 ps using the nonlinear I(V)-characteristic of the surface of highly oriented pyrolithic graphite. We provide atomically resolved images in pulse mode related to a spatially varying nonlinearity of the local density of states of the sample, thus, demonstrating the possible spatial resolution of the instrument in pulse mode. Analysis of the noise reveals that changes in the tunneling junction of 50 pA are dynamically detectable at 120 ps time resolution.