The role of Joule heating in the formation of nanogaps by electromigration

TL;DR

This paper explores how Joule heating influences nanogap formation in gold wires during electromigration, showing that controlling resistance can prevent melting and enable precise gap creation.

Contribution

It demonstrates that Joule heating is crucial for nanogap formation and introduces a method to control breaking dynamics without active feedback.

Findings

Breaking occurs at ~400 K local temperature due to Joule heating.

Minimizing series resistance limits temperature rise and prevents melting.

Quantized conductance steps observed before gap formation.

Abstract

We investigate the formation of nanogaps in gold wires due to electromigration. We show that the breaking process will not start until a local temperature of typically 400 K is reached by Joule heating. This value is rather independent of the temperature of the sample environment (4.2-295 K). Furthermore, we demonstrate that the breaking dynamics can be controlled by minimizing the total series resistance of the system. In this way, the local temperature rise just before break down is limited and melting effects are prevented. Hence, electrodes with gaps < 2 nm are easily made, without the need of active feedback. For optimized samples, we observe quantized conductance steps prior the gap formation.