Chloride Molecular Doping Technique on 2D Materials: WS2 and MoS2

Low-resistivity metal-semiconductor (M-S) contact is one of the urgent challenges in the research of 2D transition metal dichalcogenides (TMDs). Here, we report a chloride molecular doping technique which greatly reduces the contact resistance (R-c) in the few-layer WS2 and MoS2. After doping, the R-c of WS2 and MoS2 have been decreased to 0.7 k Omega center dot mu m and 0.5 k Omega center dot mu m, respectively. The significant reduction of the R-c is attributed to the achieved high electron-doping density, thus a significant reduction of Schottky barrier width. As a proof-of-concept, high-performance few-layer WS2 field-effect transistors (FETs) are demonstrated, exhibiting a high drain current of 380 mu A/mu m, an on/off ratio of 4 x 10(6), and a peak field-effect mobility of 60 cm(2)/(V.s). This doping technique provides a highly viable route to diminish the Rc in TMDs, paving the way for high-performance 2D nanoelectronic devices.