Determination of the Impact of Thermal Annealing on the Interface Between Monolayer MoS₂and Au by In-Situ Raman Spectroscopy

We have performed in-situ Raman study to determine the impact of thermal annealing on the device-relevant interface between single layer MoS₂ and Au. Our data indicates that the MoS­₂/Au interface has strongly- and weakly-coupled regions. Raman spectra has been used to track the doping and the strain levels of these regions as a function of the annealing temperature, up to 300 . Weakly-coupled regions begin hole-doped (~5x10¹²/cm²) upon exfoliation of MoS₂ on Au and trend towards charge-neutral as the annealing temperature is increased. Further, strongly-coupled regions are electron-doped (~3.5x10¹³/cm²) with the doping level unaffected by annealing. The strain remains constant upon annealing with weakly-coupled regions having 1.0% strain and the strongly-coupled region having 0.2% strain. We compare our results to our previous study [1] using scanning tunneling microscopy (STM) and ultraviolet and x-ray photoelectron spectroscopy (UPS/XPS) and conclude that annealing increases the fraction of the MoS₂ regions that are strongly-coupled to Au.