Au and Ti induced charge redistributions on monolayer WS₂

By using the first-principles calculations, structural and electronic properties of Au and Ti adsorbed WS₂ monolayers are studied systematically. For Au-adsorbed WS₂, metallic interface states are induced in the middle of the band gap across the Fermi level. These interface states origin mainly from the Au-6s states. As to the Ti adsorbed WS₂, some delocalized interface states appear and follow the bottom of conduction band. The Fermi level arises into the conduction band and leads to the n-type conducting behavior. The n-type interface states are found mainly come from the Ti-3d and W-5d states due to the strong Ti–S hybridization. The related partial charge densities between Ti and S atoms are much higher and increased by an order of magnitude as compared with that of Au-adsorbed WS₂. Therefore, the electron transport across the Ti-adsorbed WS₂ system is mainly by the resonant transport, which would further enhances the electronic transparency when monolayer WS₂ contacts with metal Ti. These investigations are of significant importance in understanding the electronic properties of metal atom adsorption on monolayer WS₂ and offer valuable references for the design and fabrication of 2D nanodevices.