Bidirectional heterostructures consisting of graphene and lateral MoS2/WS2 composites: a first-principles study

摘要

First-principles calculations have been performed to explore the structural and electronic properties of bidirectional heterostructures composed of graphene and (MoS _(2) ) _( X ) /(WS _(2) ) _(4? X ) ( X = 1, 2, 3) lateral composites and compare them with those of heterobilayers formed by graphene and pristine MS _(2) (M = Mo, W). The band gaps of the lateral heterostructures lie between those of pristine MoS _(2) and WS _(2) . The weak coupling between the two layers can induce a tiny band-gap opening of graphene and formation of an n-type Schottky contact at the G-(MoS _(2) ) _( X ) /(WS _(2) ) _(4? X ) interface. Moreover, the combination ratio of MoS _(2) /WS _(2) can control the electronic properties of G-(MoS _(2) ) _( X ) /(WS _(2) ) _(4? X ) . By applying external electric fields, the band gaps of (MoS _(2) ) _( X ) /(WS _(2) ) _(4? X ) ( X = 0, 1, 2, 3, 4) monolayers undergo a direct–indirect transition, and semiconductor–metal transitions can be found in WS _(2) . External electric fields can also be used effectively to tune the binding energies, charge transfers, and band structures (the types of Schottky and Ohmic contacts) of G-(MoS _(2) ) _( X ) /(WS _(2) ) _(4? X ) heterostructures. These findings suggest that G-(MoS _(2) ) _( X ) /(WS _(2) ) _(4? X ) heterostructures can serve as high-performance nano-electronic devices.