Computational Design of Silicon Contacts on 2D Transition-Metal Dichalcogenides: The Roles of Crystalline Orientation, Doping Level, Passivation and Interfacial Layer

Systematic numerical simulations based on density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalism have been carried out for comprehensive understanding of the physical properties of silicon (Si) contacts on monolayer transition metal dichalcogenides (TMDs). The effects of different contact crystalline orientations including Si (001), (110) and (111), Si doping levels, possible surface passivation such as H- and F-, as well as interfacial layer (IL) engineering using BN and Graphene are thoroughly discussed. On the one hand, it is found that the contact properties of different crystalline orientations follow similar trend, and the doping modulation of the Schottky barrier height (SBH) remains inappreciable in a practical range of doping level. On the other hand, H- and F- passivation are found to be effective ways to diverge the intrinsic contact into n - and p - type contacts, respectively. In addition, it is found that surprisingly good p-type contact with vanishing p-SBH could be formed by using monolayer BN as the IL.