Towards Perfect Absorption of Single Layer CVD Graphene in an Optical Resonant Cavity: Challenges and Experimental Achievements.

Abedin Nematpour,Laura Lancellotti,Maria Luisa Grilli,Nicola Lisi

doi:10.3390/ma15010352

Abedin Nematpour, Laura Lancellotti + Show 2 more

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https://doi.org/10.3390/ma15010352

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Abstract

Graphene is emerging as a promising material for the integration in the most common Si platform, capable to convey some of its unique properties to fabricate novel photonic and optoelectronic devices. For many real functions and devices however, graphene absorption is too low and must be enhanced. Among strategies, the use of an optical resonant cavity was recently proposed, and graphene absorption enhancement was demonstrated, both, by theoretical and experimental studies. This paper summarizes our recent progress in graphene absorption enhancement by means of Si/SiO2-based Fabry–Perot filters fabricated by radiofrequency sputtering. Simulations and experimental achievements carried out during more than two years of investigations are reported here, detailing the technical expedients that were necessary to increase the single layer CVD graphene absorption first to 39% and then up to 84%. Graphene absorption increased when an asymmetric Fabry–Perot filter was applied rather than a symmetric one, and a further absorption increase was obtained when graphene was embedded in a reflective rather than a transmissive Fabry–Perot filter. Moreover, the effect of the incident angle of the electromagnetic radiation and of the polarization of the light was investigated in the case of the optimized reflective Fabry–Perot filter. Experimental challenges and precautions to avoid evaporation or sputtering induced damage on the graphene layers are described as well, disclosing some experimental procedures that may help other researchers to embed graphene inside PVD grown materials with minimal alterations.

Highlights

Graphene-based absorbers are receiving a considerable interest due to their potential applications in photovoltaics [1,2,3], as wave modulators [4,5,6,7,8], biological sensors [9,10,11], photodetectors [12,13,14,15], etc
We summarize our recent studies [67,68,69] on CVD graphene absorption inside three different Fabry–Perot (FP) filters fabricated by radiofrequency sputtering
This work summarizes our recent findings on single layer graphene absorption when

Summary

Introduction

Graphene-based absorbers are receiving a considerable interest due to their potential applications in photovoltaics [1,2,3], as wave modulators [4,5,6,7,8], biological sensors [9,10,11], photodetectors [12,13,14,15], etc. In the THz and IR regions, high quality graphene may show strong interaction with light thanks to generation of surface plasmon polaritons (SPPs), making graphene a promising alternative to typical plasmonic materials [22,23,24,25]. This is thanks to the capability of graphene to support plasmon modes with extremely tight confinement, long lifetime, and low losses at IR and THz frequencies [26,27,28,29]. In the Vis and NIR regions, on the contrary, absence of SSPs makes it necessary to couple graphene with resonant structures such as metamaterials, photonic crystals and plasmonic materials [33,34,35,36,37,38,39]

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