We fabricate and characterize mono- and few- layers of MoS2 and WSe2 on glass and SiO2/Si substrates. PbS quantum dots and/or Au nanoparticles are deposited on the fabricated thin metal dichalcogenide films by controlled drop casting and electron beam evaporation techniques. The reflection spectra of the fabricated structures are measured with a spatially resolved reflectometry setup. Both experimental and numerical results show that surface functionalization with metal nanoparticles can enhance atomically thin transition metal dichalcogenides’ absorption and scattering capabilities, however semiconducting quantum dots do not create such effect.
In order to protect optoelectronic and mechanical properties of atomically thin layered materials (ATLMs) fabricated over SiO2/Si substrates, a secondary oxide or nitride layer can be capped over. However, such protective capping might decrease ATLMs’ visibility dramatically. Similar to the early studies conducted for graphene, we numerically determine optimum thicknesses both for capping and underlying oxide layers for strongest visibility of monolayer MoS2, MoSe2, WS2, and WSe2 in different regions of visible spectrum. We find that the capping layer should not be thicker than 60 nm. Furthermore the optimum capping layer thickness value can be calculated as a function of underlying oxide thickness, and vice versa.
Graphene’s controllable optical conductivity and mechanically strong structure make it a suitable material to de- sign tunable localized surface plasmon resonance (LSPR) sensors. In this work, we theoretically and numerically demonstrate that the resonance wavelength of an LSPR sensor can be tuned to any value within a reasonably wide range of wavelengths by changing the voltage applied to graphene layer. Theoretical results reveal a higher sensitivity with respect to regular LSPR sensors.