Graphene-protected copper and silver plasmonics

TL;DR

This paper demonstrates that graphene-protected copper and silver films exhibit excellent plasmonic properties, durability, and corrosion resistance, making them promising alternatives to gold for plasmonic devices and applications.

Contribution

It introduces graphene protection as a method to stabilize copper and silver plasmonic films, surpassing gold in performance and longevity for practical applications.

Findings

Copper films with graphene show superior plasmonic characteristics.

Graphene protection enables copper and silver films to last over a year in harsh conditions.

Successful demonstration of graphene-protected copper in plasmonic waveguides.

Abstract

Plasmonics has established itself as a branch of physics which promises to revolutionize data processing, improve photovoltaics, increase sensitivity of bio-detection. A widespread use of plasmonic devices is notably hindered (in addition to high losses) by the absence of stable and inexpensive metal films suitable for plasmonic applications. This may seem surprising given the number of metal compounds to choose from. Unfortunately, most of them either exhibit a strong damping of surface plasmons or easily oxidize and corrode. To this end, there has been continuous search for alternative plasmonic materials that are, unlike gold, the current metal of choice in plasmonics, compatible with complementary metal oxide semiconductor technology. Here we show that copper and silver protected by graphene are viable candidates. Copper films covered with one to a few graphene layers show excellent plasmonics characteristics surpassing those of gold films. They can be used to fabricate plasmonic devices and survive for at least a year, even in wet and corroding conditions. As a proof of concept, we use the graphene-protected copper to demonstrate dielectric loaded plasmonic waveguides and test sensitivity of surface plasmon resonances. Our results are likely to initiate a wide use of graphene-protected plasmonics.