How to Fix Silver for Plasmonics

Fuente: arXiv
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Autori principali: Ewald, Björn, Siebigs, Leo, Zhang, Cheng, Graf, Jonas, Tiwari, Achyut, Rödel, Maximilian, Hammer, Sebastian, Stepanenko, Vladimir, Würthner, Frank, Gompf, Bruno, Hecht, Bert, Pflaum, Jens
Natura: Preprint
Pubblicazione: 2025
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author Ewald, Björn
Siebigs, Leo
Zhang, Cheng
Graf, Jonas
Tiwari, Achyut
Rödel, Maximilian
Hammer, Sebastian
Stepanenko, Vladimir
Würthner, Frank
Gompf, Bruno
Hecht, Bert
Pflaum, Jens
author_facet Ewald, Björn
Siebigs, Leo
Zhang, Cheng
Graf, Jonas
Tiwari, Achyut
Rödel, Maximilian
Hammer, Sebastian
Stepanenko, Vladimir
Würthner, Frank
Gompf, Bruno
Hecht, Bert
Pflaum, Jens
contents Silver (Ag) is considered an ideal material for plasmonic applications in the visible wavelength regime due to its superior optical properties, but its use is limited by the poor chemical stability and structural quality of thermally evaporated thin films and resulting nanostructures. In this study, we present a simple approach to enhance the structural and optical quality as well as the chemical stability of Ag thin films by alloying with gold (Au) through thermal co-evaporation. We investigate Ag$_{100-x}$Au$_x$ thin films with Au contents ranging from 5 to 20 at% analyzing their surface morphology, crystallite structure, optical properties, and chemical stability. Our results show that low Au concentrations significantly reduce the roughness of co-evaporated thin films (down to 0.4 nm RMS), and significantly enhance the resistance to oxidation, while maintaining a defined crystallite growth. Importantly, these improvements are achieved without the need for template stripping, metallic wetting layers, or epitaxial substrates, enabling direct deposition on glass. Among the compositions studied, Ag$_{95}$Au$_5$ thin films exhibit the highest chemical stability, lowest optical losses in the visible spectral range, and excellent plasmonic properties even outcompeting pure Ag. As a proof-of-concept, we fabricate high-quality Ag$_{95}$Au$_5$ optical antennas that exhibit long-term durability under ambient conditions. Our approach provides a practical solution to overcome the limitations of Ag for plasmonic device applications.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09569
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How to Fix Silver for Plasmonics
Ewald, Björn
Siebigs, Leo
Zhang, Cheng
Graf, Jonas
Tiwari, Achyut
Rödel, Maximilian
Hammer, Sebastian
Stepanenko, Vladimir
Würthner, Frank
Gompf, Bruno
Hecht, Bert
Pflaum, Jens
Materials Science
Applied Physics
Optics
Silver (Ag) is considered an ideal material for plasmonic applications in the visible wavelength regime due to its superior optical properties, but its use is limited by the poor chemical stability and structural quality of thermally evaporated thin films and resulting nanostructures. In this study, we present a simple approach to enhance the structural and optical quality as well as the chemical stability of Ag thin films by alloying with gold (Au) through thermal co-evaporation. We investigate Ag$_{100-x}$Au$_x$ thin films with Au contents ranging from 5 to 20 at% analyzing their surface morphology, crystallite structure, optical properties, and chemical stability. Our results show that low Au concentrations significantly reduce the roughness of co-evaporated thin films (down to 0.4 nm RMS), and significantly enhance the resistance to oxidation, while maintaining a defined crystallite growth. Importantly, these improvements are achieved without the need for template stripping, metallic wetting layers, or epitaxial substrates, enabling direct deposition on glass. Among the compositions studied, Ag$_{95}$Au$_5$ thin films exhibit the highest chemical stability, lowest optical losses in the visible spectral range, and excellent plasmonic properties even outcompeting pure Ag. As a proof-of-concept, we fabricate high-quality Ag$_{95}$Au$_5$ optical antennas that exhibit long-term durability under ambient conditions. Our approach provides a practical solution to overcome the limitations of Ag for plasmonic device applications.
title How to Fix Silver for Plasmonics
topic Materials Science
Applied Physics
Optics
url https://arxiv.org/abs/2507.09569