Strain and Charge Doping Fingerprints of the Strong Interaction between Monolayer MoS₂ and Gold

Gold-mediated exfoliation of MoS₂ has recently attracted considerable interest. The strong interaction between MoS₂ and Au facilitates preferential production of centimeter-sized monolayer MoS₂ with near-unity yield and provides a heterostructure system noteworthy from a fundamental standpoint. However, little is known about the detailed nature of the MoS₂-Au interaction and its evolution with the MoS₂ thickness. Here, we identify the specific vibrational and binding energy fingerprints of this interaction using Raman and X-ray photoelectron spectroscopy, which indicate substantial strain and charge doping in monolayer MoS₂. Tip-enhanced Raman spectroscopy reveals heterogeneity of the MoS₂-Au interaction at the nanoscale, reflecting the spatial nonconformity between the two materials. Micro-Raman spectroscopy shows that this interaction is strongly affected by the roughness and cleanliness of the underlying Au. Our results elucidate the nature of the MoS₂-Au interaction and guide strain and charge doping engineering of MoS₂.