Fano Resonance and Spectrally Modified Photoluminescence
Enhancement in Monolayer MoS<sub>2</sub> Integrated with Plasmonic
Nanoantenna Array
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Abstract
The
manipulation of light-matter interactions in two-dimensional atomically
thin crystals is critical for obtaining new optoelectronic functionalities
in these strongly confined materials. Here, by integrating chemically
grown monolayers of MoS<sub>2</sub> with a silver-bowtie nanoantenna
array supporting narrow surface-lattice plasmonic resonances, a unique
two-dimensional optical system has been achieved. The enhanced exciton–plasmon
coupling enables profound changes in the emission and excitation processes
leading to spectrally tunable, large photoluminescence enhancement
as well as surface-enhanced Raman scattering at room temperature.
Furthermore, due to the decreased damping of MoS<sub>2</sub> excitons
interacting with the plasmonic resonances of the bowtie array at low
temperatures stronger exciton–plasmon coupling is achieved
resulting in a Fano line shape in the reflection spectrum. The Fano
line shape, which is due to the interference between the pathways
involving the excitation of the exciton and plasmon, can be tuned
by altering the coupling strengths between the two systems via changing
the design of the bowties lattice. The ability to manipulate the optical
properties of two-dimensional systems with tunable plasmonic resonators
offers a new platform for the design of novel optical devices with
precisely tailored responses