Hole mobility enhancement and p-doping in monolayer WSe<inf>2</inf> by gold decoration

Tungsten diselenide (WSe<inf>2</inf>) is an attractive transition metal dichalcogenide material, since its Fermi energy close to the mid gap makes it an excellent candidate for realizing p-n junction devices and complementary digital logic applications. Doping is one of the most important technologies for controlling the Fermi energy in semiconductors, including 2D materials. Here we present a simple, stable and controllable p-doping technique on a WSe<inf>2</inf> monolayer, where a more p-typed WSe<inf>2</inf> field effect transistor is realized by electron transfer from the WSe<inf>2</inf> to the gold (Au) decorated on the WSe<inf>2</inf> surfaces. Related changes in Raman spectroscopy are also reported. The p-doping caused by Au on WSe<inf>2</inf> monolayers lowers the channel resistance by orders of magnitude. The effective hole mobility is ∼100 (cm²/Vs) and the near ideal subthreshold swing of ∼60mV/decade and high on/off current ratio of >106 are observed. The Au deposited on the WSe<inf>2</inf> also serves as a protection layer to prevent a reaction between the WSe<inf>2</inf> and the environment, making the doping stable and promising for future scalable fabrication.