Temperature-dependent permittivity of annealed and unannealed gold films

TL;DR

This study measures how gold's permittivity changes with temperature, revealing significant differences between annealed and unannealed films, which impacts the design of thermo-plasmonic devices.

Contribution

It provides the first detailed characterization of gold permittivity across a wide temperature range, highlighting the effects of annealing on thermo-derivative.

Findings

Over one-order difference in thermo-derivative of permittivity between annealed and unannealed films

Large variation in plasmonic properties due to temperature effects

Data useful for designing thermo-nano-plasmonic systems

Abstract

Due to local field enhancement and subwavelength confinements, nano-plasmonics provide numerous novel applications. Simultaneously, as an efficient nanoscale heat generator from inherent absorption, thermo-plasmonics is emerging as an important branch. However, although significant temperature increase is involved in applications, detailed characterization of metal permittivity at different temperatures and corresponding thermo-derivative are lacking. In this work, we extract the permittivity of gold from 300K to the annealing temperature of 570K. By comparing annealed and unannealed films, more than one-order difference in thermo-derivative of permittivity is revealed, resulting in unexpectedly large variation of plasmonic properties. Our result is valuable not only for characterizing extensively used unannealed nanoparticles, but also for designing future thermo-nano-plasmonic systems.