Electronic Changes in Molybdenum Dichalcogenides on Gold Surfaces

X-ray and ultraviolet photoelectron spectroscopy are performed on transition metal dichalcogenides (TMDs) MoS2, MoSe2, and MoTe2 monolayers on Au surfaces, to identify charge transfer processes and changes in structural phase upon annealing up to 500 degrees C. Although charge transfer does appear to occur as the spacing between the TMD monolayer and the Au surface decreases, we do not find spectroscopic evidence for the 2H to 1T phase change in exfoliated TMDs. However, we find the defect density of the TMDs influences the evolution of the X-ray photoelectron spectra during thermal treatment on Au. Both metal-organic chemical vapor deposition grown and helium-ion irradiated exfoliated-TMDs annealed on Au surfaces show shifts in their spectra that could be interpreted as a phase change, but are the result of TMD/Au hybridization, grain boundaries and defects interacting with the Au surface.