Enhanced light absorption in monolayer tungsten disulfide with dielectric Bragg reflector and metallic thin film

Abstract

Abstract A multi-layer structure based on the microcavity effect of a dielectric Bragg reflector (DBR) and metallic thin film to enhance light absorption of monolayer tungsten disulfide (WS2) is proposed. This structure is combined with a cover layer and a spacer layer to adjust the phase-matching condition. The transfer matrix method (TMM) was used to study its optical transport characteristics. It was found that the microcavity effect of DBR and the metallic thin film forms a maximum value of electric field intensity near the monolayer WS2, which effectively promotes the light-matter interaction in monolayer WS2. As the thicknesses of the spacer layer and cover layer were comprehensively optimized, the light absorption of monolayer WS2 at the wavelength of 611 nm reached 94.38 % and the full width at half maximum (FWHM) is only 9 nm. Furthermore, the effect of DBR periodicity and angle of incidence on the light absorption of monolayer WS2 were discussed. The research presented here confirms that changing the above structural parameters can effectively regulate the absorption peak wavelength and maximum value of monolayer WS2. The results of this study provide new ideas for the preparation of high-performance monolayer WS2 photodetectors and other new optoelectronic devices.