Plasmon Resonance in Multilayer Graphene Nanoribbons

TL;DR

This study investigates plasmon resonance in multilayer graphene nanoribbons through experiments and simulations, revealing tunable plasmons and the effects of layer stacking on resonance strength.

Contribution

First experimental verification of electrically tunable plasmons in multilayer graphene nanoribbons with detailed numerical simulation validation.

Findings

Resonance strength increases from single to double layer GNRs.

No significant resonance increase from double to triple layer GNRs.

Simulations closely match experimental results for unpatterned graphene.

Abstract

Plasmon resonance in nanopatterned single layer graphene nanoribbon (SL-GNR), double layer graphene nanoribbon (DL-GNR) and triple layer graphene nanoribbon (TL-GNR) structures is studied both experimentally and by numerical simulations. We use 'realistic' graphene samples in our experiments to identify the key bottle necks in both experiments and theoretical models. The existence of electrical tunable plasmons in such stacked multilayer GNRs was first experimentally verified by infrared microscopy. We find that the strength of the plasmonic resonance increases in DL-GNR when compared to SL-GNRs. However, we do not find a further such increase in TL-GNRs compared to DL-GNRs. We carried out systematic full wave simulations using finite element technique to validate and fit experimental results, and extract the carrier scattering rate as a fitting parameter. The numerical simulations show remarkable agreement with experiments for unpatterned SLG sheet, and a qualitative agreement for patterned graphene sheet. We believe that further improvements such as introducing a bandgap into the numerical model could lead to a better quantitative agreement of numerical simulations with experiments. We also note that such advanced modeling would first require better quality graphene samples and accurate measurements.