Thickness scaling effect on interfacial barrier and electrical contact to two-dimensional MoS₂ layers

Understanding the interfacial electrical properties between metallic electrodes and low-dimensional semiconductors is essential for both fundamental science and practical applications. Here we report the observation of thickness reduction induced crossover of electrical contact at Au/MoS₂ interfaces. For MoS₂ thicker than 5 layers, the contact resistivity slightly decreases with reducing MoS₂ thickness. By contrast, the contact resistivity sharply increases with reducing MoS₂ thickness below 5 layers, mainly governed by the quantum confinement effect. We find that the interfacial potential barrier can be finely tailored from 0.3 to 0.6 eV by merely varying MoS₂ thickness. A full evolution diagram of energy level alignment is also drawn to elucidate the thickness scaling effect. The finding of tailoring interfacial properties with channel thickness represents a useful approach controlling the metal/semiconductor interfaces which may result in conceptually innovative functionalities.