Feedback controlled electromigration in four-terminal nano-junctions

TL;DR

This paper presents a rapid, reproducible method for fabricating nanoscale metallic electrodes using feedback-controlled electromigration in four-terminal devices, enabling precise gap formation in the quasi-ballistic regime.

Contribution

It introduces a novel feedback-controlled electromigration technique with four-terminal configuration for improved control over nanoscale electrode fabrication.

Findings

Electromigration can be precisely controlled in the quasi-ballistic regime.

The method achieves rapid and reproducible nanogap formation.

Temperature increases significantly during initial electromigration phase.

Abstract

We have developed a fast, yet highly reproducible method to fabricate metallic electrodes with nanometer separation using electromigration (EM). We employ four-terminal instead of two-terminal devices in combination with an analog feedback to maintain the voltage $U$ over the junction constant. After the initialization phase ($U < 0.2V), during which the temperature $T$ increases by 80-150 degs C, EM sets in shrinking the wire locally. This quickly leads to a transition from the diffusive to a quasi-ballistic regime ($0.2V < U < 0.6V). At the end of this second regime, a gap forms (U > 0.6V). Remarkably, controlled electromigration is still possible in the quasi-ballistic regime.