Au nanowire junction breakup through surface atom diffusion

TL;DR

This study investigates how gold nanowire junctions break up due to surface atom diffusion at elevated temperatures, revealing that junctions are more prone to fragmentation, which can be controlled for nanodot array fabrication.

Contribution

The paper introduces a kinetic Monte Carlo model for gold nanowire junction breakup driven by surface diffusion, supported by experimental annealing data.

Findings

Junctions break up at lower temperatures than single nanowires.

Fragmentation is highly temperature dependent.

Aligning nanowires can facilitate nanodot array fabrication.

Abstract

Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200, 400, 600 and 700 {\deg}C) during a time period of 10 minutes. We show that nanowires are especially prone to fragmentation around junctions and crossing points even at comparatively low temperatures. The fragmentation process is highly temperature dependent and the junction region breaks up at a lower temperature than a single nanowire. We develop a gold parametrization for Kinetic Monte Carlo simulations and demonstrate the surface diffusion origin of the nanowire junction fragmentation. We show that nanowire fragmentation starts at the junctions with high reliability and propose that aligning nanowires in a regular grid could be used as a technique for fabricating arrays of nanodots.