Fig. 1: The Au-WS₂-Au junction and modulation of excitonic emission under lateral DC bias.

a Schematic illustration of the Au-WS₂-Au junction. b Optical micrograph of the fabricated device with the monolayer boundary indicated by the white dashed line. c DC bias induced modulation of excitonic emission. Bias of +5 V was applied to the left electrode while the right electrode was grounded. The red line and black line indicate the excitonic emission intensity and the DC bias, respectively. The insets show the fluorescence images at specific times, where the scale bars indicate 10 μm. Energy level diagrams of the junction under zero bias (d) and positive bias (e) conditions. Bias-dependent carrier (e^-, electrons and h⁺, holes) trapping/detrapping happens at the Au/WS₂ interface, followed by carrier drift (blue dashed arrows) in the monolayer plane due to bias-induced band bending. E_F means the Fermi level of the Au electrode.