Interfacial Properties of MoS₂ Thin Films Grown on Functional Substrates

Interface chemistry and defect formation in MoS₂ thin films grown on single crystal substrates critically determine the electronic structure of MoS₂ and thus can strongly modify material functionality relevant for many applications, including electronics, optoelectronics, and energy-related catalysis. We investigate MoS₂ grown on three technologically relevant substrates, namely SrTiO₃(111), c-axis Al₂O₃(0001) and 6H-SiC(0001). Experimental investigations by temperature dependent resistivity, photoemission spectroscopy and scanning transmission electron microscopy with coupled energy dispersive spectroscopy, with the support of theoretical calculation by Density Functional Theory, allow the identification of the substrate induced specific defects and their correlation with the electronic properties. Ti interdiffusion in SrTiO₃/MoS₂ generates p-type states near the Fermi level, leading to metallic transport. Al₂O₃/MoS₂ exhibits a high density of sulfur-related defects that introduce localized states and yield nearly temperature independent conductivity. SiC/MoS₂ exhibits significant interface disorder resulting in a semiconducting temperature dependent resistivity, yet deviating from the ideal bulk-like behavior. These results demonstrate how substrate choice governs defect formation and ultimately dominates the electronic behavior of MoS₂ thin films, making the control of film/substrate interactions essential for the engineering of new functional devices.