True Alternating Current Scanning Tunneling Microscope (ACSTM): tunneling on insulators

TL;DR

The paper introduces a novel ACSTM technique that enables atomic-resolution imaging on insulators and provides high-frequency electronic information, expanding STM capabilities beyond conductive samples.

Contribution

A new ACSTM method that operates without DC current, allowing atomic imaging on insulators and access to high-frequency electronic data.

Findings

Achieved atomic resolution imaging on insulating surfaces like glass and oxides.

Demonstrated measurement on 25nm thick silicon oxide at 10 MHz.

Enabled access to high-frequency electronic sample information.

Abstract

Scanning Tunneling Microscopy (STM) has revolutionized our atomic scale understanding of surfaces and accelerated progress in nanotechnology. This technique, however, is restricted to metal or semiconducting samples, as it requires a tiny current to stabilize the tip-sample distance with atomic scale precision. We developed a new imaging and feedback method that relies on true alternating current (AC) without any direct current (DC) component. This technique does not only enable the imaging on non-conducting surfaces with atomic resolution, like (thin) glass and oxides, it provides also access to high-frequency electronic sample information. We demonstrate that it is possible to measure on 25nm thick silicon oxide with 10 MHz tunneling current.