Nanogaps with very large aspect ratios for electrical measurements

TL;DR

This paper presents a self-aligned fabrication process for creating nanoscale metal electrodes with extremely high aspect ratios and very small gaps, enabling advanced electrical measurements on nanostructures.

Contribution

A novel self-aligned method using a Cr sacrificial layer to produce large aspect ratio nanogaps below 100 nm with excellent isolation.

Findings

Gaps as small as 10 nm achieved

Aspect ratios exceeding 1000 demonstrated

Effective on reactive substrates like Si

Abstract

For nanoscale electrical characterization and device fabrication it is often desirable to fabricate planar metal electrodes separated by large aspect ratio gaps with interelectrode distances well below 100 nm. We demonstrate a self-aligned process to accomplish this goal using a thin Cr film as a sacrificial etch layer. The resulting gaps can be as small as 10 nm and have aspect ratios exceeding 1000, with excellent interelectrode isolation. Such Ti/Au electrodes are demonstrated on Si substrates and are used to examine a voltage-driven transition in magnetite nanostructures. This shows the utility of this fabrication approach even with relatively reactive substrates.