Morphology-Driven Interfacial Coupling in Monolayer MoS2 on Gold

Abstract Properties of transition metal dichalcogenide monolayers are strongly modified when interfaced with metals rather than weakly interacting substrates such as SiO2. For monolayer MoS2 on Au, the vibrational spectrum serves as a sensitive probe of substrate-driven charge transfer, strain, and hybridization. However, how these interactions evolve in response to roughness-induced changes in Au surface morphology remains poorly understood. Here, we investigate monolayer MoS2 exfoliated onto Au films with varying surface roughness and show that its properties are governed by the balance between regions that conform to the underlying Au surface and regions that remain locally suspended. Correlative analyses combining atomic force microscopy, Raman/photoluminescence spectroscopy, and molecular dynamics simulations reveal that increasing substrate roughness hinders conformal contact between MoS2 and Au, promotes the formation of locally suspended regions, and enhances tensile strain in the monolayer. Furthermore, we demonstrate that incorporating a Pt adhesion layer yields exceptionally smooth Au surfaces, enabling efficient exfoliation even on ultrathin Au films and providing a cost-effective route toward large-area monolayer preparation. These findings establish interfacial morphology as a key parameter governing the mechanical, vibrational, and optical properties of monolayer MoS2 and provide practical design guidelines for engineering metal−2D material interfaces for (opto)electronic, catalytic, and sensing applications.