Structures, Energetics, and Electronic Properties of Multifarious Stacking Patterns for High-Buckled and Low-Buckled Silicene on the MoS2 Substrate

The interfaces between silicene and substrate materials play important roles in the electronic properties of the systems. High-buckled (HB) silicene synthesized on bulk MoS2 surface has been reported [Adv. Mater. 2014, 26, 2096-2101]. Using first-principles calculations, we studied the interfaces between silicene and the monolayer MoS2 substrate. We found that silicene can adsorb on the MoS2 substrate via van der Waals (vdW) interactions forming silicene/MoS2 heterostructures with HB or low-buckled (LB) configuration. The lattice mismatch between LB silicene and the MoS2 substrate leads to the formation of Moire superstructures. The heterostructures of HB silicene on the MoS2 substrate are metallic, while those of LB silicene on the MoS2 substrate are semiconductors with small band gaps due to the interface effects. The band gap is dependent on the rotation angle and stacking pattern, whereas the formation energy is not. High carrier mobility of LB silicene is preserved in these heterostructures. More interestingly, the band gap can be further tuned by applying a vertical external electric field. These features are helpful for the fabrication of nanoscaled electronic devices using silicene.