Controlled Fabrication of Nanogaps in Ambient Environment for Molecular Electronics

TL;DR

This paper presents a reproducible ambient-condition electromigration method for fabricating nanogaps suitable for single-molecule electronics, overcoming temperature and resistance control limitations of previous techniques.

Contribution

It introduces a controlled fabrication process for nanogaps in ambient conditions, enabling precise resistance tuning and compatibility with fragile biomolecules.

Findings

Achieved reproducible nanogap formation in ambient environment.

Controlled nanogap resistance matching specific tunnelling requirements.

Identified three regimes of nanogap evolution during electromigration.

Abstract

We have developed a controlled and highly reproducible method of making nanometer-spaced electrodes using electromigration in ambient lab conditions. This advance will make feasible single molecule measurements of macromolecules with tertiary and quaternary structures that do not survive the liquid-helium temperatures at which electromigration is typically performed. A second advance is that it yields gaps of desired tunnelling resistance, as opposed to the random formation at liquid-helium temperatures. Nanogap formation occurs through three regimes: First it evolves through a bulk-neck regime where electromigration is triggered at constant temperature, then to a few-atom regime characterized by conductance quantum plateaus and jumps, and finally to a tunnelling regime across the nanogap once the conductance falls below the conductance quantum.