Influence of direct deposition of dielectric materials on the optical response of monolayer WS₂

The integration of two-dimensional transition metal dichalcogenide crystals (TMDCs) into a dielectric environment is critical for optoelectronic and photonic device applications. Here, we investigate the effects direct deposition different materials (Al$_2$O$_3$, SiO$_2$, SiN$_x$) onto atomically thin (monolayer) TMDC WS$_2$ on its optical response. Atomic layer (ALD), electron beam evaporation (EBE), plasma enhanced chemical vapour (PECVD), magnetron sputtering methods material are investigated. photoluminescence (PL) measurements reveal quenching excitonic emission after all processes. reduction in neutral exciton PL linked to increased level charge doping associated rise trion emission, and/or localized (bound) emission. Furthermore, Raman spectroscopy allows us clearly correlate observed changes with levels lattice disorder defects. Overall, EBE process results lowest defect densities preserves spectral weight PL, as well oscillator strength. Encapsulation ALD appears cause changes, which makes it distinct from other techniques. Sputtering revealed most aggressive method WS$_2$, fully Our demonstrate quantify monolayer can provide valuable guidance efforts integrate TMDCs functional devices.