Plasmon-induced hot electron injection and local surface potential modification in WS2/Au-nanogratings

The integration of metal nanostructures and transition metal dichalcogenides (TMDs) can lead to exciton-plasmon coupling, which can provide a platform to investigate intriguing physics and cutting-edge applications. In this work, we fabricated hybrid systems, consisting of WS2 multilayer flakes and Au nanogratings (AuNGs), and investigated their optical and electrical characteristics. WS2 flakes were directly exfoliated on large-area AuNGs, prepared by evaporation of Au thin films on Blu-ray disc templates. The polarization- and angle-dependence of the reflectance spectra of WS2/AuNGs indicated surface plasmon polariton (SPP) excitation and SPP-exciton coupling in the visible wavelength range. The surface potential maps in WS2/AuNGs, acquired by Kelvin probe force microscopy, could visualize how the SPP-exciton coupling affected the creation and redistribution of charge carriers. The SPP-induced hot electron injection from AuNG to WS2 as well as band-to-band excitation in WS2 contributed to the local modification of the potential distribution under light illumination.