Monolayer Excitonic Semiconductors Integrated with Au Quasi-Periodic Nanoterrace Morphology on Fused Silica Substrates for Light-Emitting Devices

Two-dimensional transition metal dichalcogenides (TMDs) have a promising future in the nanophotonics field due to their unique optoelectronic properties such as large exciton binding energies and carrier mobility. Among these properties, monolayer TMDs exhibit enhanced photoluminescence (PL) by utilizing micro-/nanostructure surface plasmon polariton (SPP) modes. In this work, we present a unique technique to achieve substantial PL enhancement by integrating MoS2 monolayers to gold quasi-periodic nanoterrace morphology with gradient periods on fused silica substrates. Gold quasi-periodic nanostructures were fabricated through cost-effective and fast ion bombardment with iron co-deposition followed by a gold coating technique, and monolayers were deposited by a polymer-assisted technique. Our results show clear evidence that the light emission is enhanced due to the SPP modes produced by the quasi-periodic nanoterrace morphology. Comprehensive spectroscopy studies were performed on monolayer flakes with different laser polarizations, morphology periods, and temperatures to offer detailed insights on the mechanism behind PL enhancement. Together with numerical simulations, our results provided a basis for understanding the PL enhancement effects and shed light on future directions of high-efficiency light-emitting devices such as diodes, lasers, and heterostructure solar cells based on TMD monolayers.