Carrier dynamics in ultrathin gold nanowires: Role of Auger processes

TL;DR

This study investigates ultrafast carrier dynamics in 2 nm gold nanowires, revealing that Auger processes significantly slow down hot carrier cooling, with implications for nanostructure-based optoelectronic applications.

Contribution

It demonstrates the role of Auger-assisted processes in carrier dynamics of ultrathin gold nanowires, providing a rate equation model and estimating the Auger coefficient.

Findings

Carrier cooling is slower than two-temperature model predictions.

Auger-assisted carrier heating significantly influences dynamics.

Estimated Auger coefficient for gold nanostructures.

Abstract

Carrier dynamics in metallic nanostructures is strongly influenced by their confining dimensions. Gold nanoparticles of size $\sim 2$ nm lie at the boundary separating metallic and non-metallic behavior. In this work, we report carrier dynamics in high aspect ratio ultrathin gold nanowires (Au-UNWs) of average diameter $\sim$2 nm using pump (3.1 eV) and coherent white light continuum as probe in the spectral range of 1.15 eV to 2.75 eV. The transient carrier dynamics in Au-UNWs under extreme excitation regime is slower than predicted by the often used two temperature model. We identify Auger-assisted carrier heating process which slows down the hot carrier cooling dynamics. The rate equation model fitted to the data yields an estimate of Auger coefficient for gold nanostructures.