Screening and interlayer coupling in multilayer MoS₂

The two-dimensional layered semiconducting di-chalcogenides are emerging as promising candidates for post-Si-CMOS applications owing to their excellent electrostatic integrity and the presence of a finite energy bandgap, unlike graphene. However, in order to unravel the ultimate potential of these materials, one needs to investigate different aspects of carrier transport. In this Letter, we present the first comprehensive experimental study on the dependence of carrier mobility on the layer thickness of back-gated multilayer MoS₂ field-effect transistors. We observe a non-monotonic trend in the extracted effective field-effect mobility with layer thickness which is of relevance for the design of high-performance devices. We also discuss a detailed theoretical model based on Thomas-Fermi charge screening and interlayer coupling in order to explain our experimental observations. Our model is generic and, therefore, is believed to be applicable to any two-dimensional layered system. A model explaining the experimental findings related to screening and interlayer coupling in multilayer MoS₂.