Enhancement of light absorption in a WS2 monolayer using spacer andAg plasmonic layers

Among 2D nanomaterials, WS2 monolayers with a direct bandgap and sharp absorption at 619 nm have  opened a new horizon for the use of these materials in photonics and electropopics. In this paper, in order to increase the absorption, the role of Ag thin film as a plasmonic layer on the substrate and also,  the effect  of spacer and cover layers are theoretically investigated. The optical properties of the designed structures are investigated by the transfer matrix method in the visible wavelength region. In the structure consisting of a WS2 monolayer with Ag and spacer layers, the absorption at 619 nm was increased to 57%. Sharp optical absorption as high as 40% for a large range of incidence angles in both polarizations was retained, giving  a good perspective on the realization of WS2 applications