Light-matter interaction between few-layer MoS₂ and electrically driven plasmonic tunnel junctions

Optically-active two-dimensional materials combined with nano-plasmonic systems provide great potential for exploring light-matter interactions. Recent photoluminescence studies of 2D materials coupled to plasmonic resonators have shown evidence of strong light-matter couplings.  In this work, we investigated the interactions between few-layer MoS₂ and electromigrated Au tunnel junctions similar to those that have been studied previously through electroluminescence. When biased into the electroluminescent regime, on top of the broad plasmonic resonance, we observed a feature at ~1.9 eV which matches the exciton energy of MoS₂. The exciton in these devices could be either excited optically by light emission from the metal electroluminescence, or excited directly by plasmon-induced hot carriers. Intriguingly, the spectra show a Fano-like shape indicating an interaction between the exciton mode and plasmonic resonance. Moreover, highly localized plasmon-enhanced Raman scattering from MoS₂ was observed at the junction, which provides sub-nanometers spatial resolution indicating nanometer-scale field enhancements. We report progress on experiments to further reveal the nature of exciton-plasmon interaction throughe gate-tunable carrier density in MoS₂.