Strong interfacial interaction and enhanced optical absorption in graphene/InAs and MoS2/InAs heterostructures

Vertical heterostructures of two-dimensional materials have recently emerged as a promising application in designing novel electronic and optoelectronic devices. By using first principles methods, we investigated the electronic and optical properties of two heterostructures, graphene/InAs and MoS2/InAs. The results reveal that the interfacial structure, coupling, and transfer charges are crucial to enhance the electronic properties and optical adsorption of heterostructures. We found obvious electron-hole pair separation and an in-built polarized electric field at the interface in graphene/InAs heterostructures. In particular, the strong interface electronic coupling opens a 15 meV band gap in graphene after the adsorption on an InAs slab substrate. Benefiting from the interfacial coupling and transfer charge, the optical properties of graphene/InAs heterostructures are slightly enhanced compared to those of isolated composites of heterostructures. Remarkably, MoS2/InAs heterostructures were found to have a larger redistribution of charge, a smaller interlayer distance, and a stronger interfacial interaction than graphene/InAs heterostructures. The calculated optical absorption of MoS2/InAs heterostructures shows more significant absorption properties in the visible region than that of graphene/InAs heterostructures. The mechanisms to understand these phenomena are suggested.