A systematic study of the synthesis of monolayer tungsten diselenide films on gold foil

We report a systematic study of the synthesis of large-area monolayer WSe2 on gold foil by controlling the growth temperature and the partial pressure of hydrogen during chemical vapor deposition. The gold surface causes surface-mediated growth to form monolayer WSe2 films. The amount of the tungsten source is controlled by adjusting the partial pressure of hydrogen, which plays a role in the reduction of WO3 (solid phase) into WO3-x (vapor phase). The coverage of monolayer WSe2 can be effectively controlled by changing either the partial pressure of hydrogen or the growth temperature at a fixed growth time under an Se-rich atmosphere, resulting in 100% coverage of the WSe2 film. The crystallinity and thickness uniformity are characterized by Raman spectroscopy, photoluminescence, and transmission electron microscopy. This characterization reveals that the quality of the WSe2 film is comparable to mechanically-exfoliated monolayer WSe2 and possesses good thickness uniformity. (C) 2016 Elsevier B.V. All rights reserved.