Stratified Graphene-Noble Metal Systems for Low-Loss Plasmonics Applications

TL;DR

This paper introduces a layered composite structure with graphene, noble metals, and hBN to achieve tunable, low-loss surface plasmon resonances, enhancing plasmonic performance for potential applications.

Contribution

It presents a novel layered design and a systematic model for tunable, low-loss plasmonics using graphene, noble metals, and hBN substrates, with detailed spectral analysis.

Findings

Bulk plasmon losses can be significantly reduced.

Surface coupling is enhanced through the layered structure.

Plasmon peak tunability is demonstrated across various configurations.

Abstract

We propose a composite layered structure for tunable, low-loss plasmon resonances, which con- sists of a noble-metal thin film coated in graphene and supported on a hexagonal boron nitride (hBN) substrate. We calculate electron energy loss spectra (EELS) for these structures, and nu- merically demonstrate that bulk plasmon losses in noble-metal films can be significantly reduced, and surface coupling enhanced, through the addition of a graphene coating and the wide-bandgap hBN substrate. Silver films with a trilayer graphene coating and hBN substrate demonstrated sur- face plasmon-dominant spectral profiles for metallic layers as thick as 34 nm. A continued-fraction expression for the effective dielectric function, based on a specular reflection model which includes boundary interactions, is used to systematically demonstrate plasmon peak tunability for a variety of configurations. Variations include substrate, plasmonic metal, and individual layer thickness for each material. Mesoscale calculation of EELS is performed with individual layer dielectric functions as input to the effective dielectric function calculation, from which the loss spectra are directly determined.