Research On Modulating Electronic Structure Of Graphene/MoSSe Heterostructures

Due to their excellent properties and potential application prospects,twodimensional transition metal dichalcogenides have attracted extensive attention both theoretically and experimentally.Base on the Janus MoSSe which has been successfully synthesized experimentally,a theoretically more stable non-Janus MoSSe has been proposed by proper exchanges of equivalent S and Se atoms.Firstly,this work investigates the structure and electronic properties of(non-)Janus MoSSe,and then stack them with graphene,investigating the most stable configuration.Interlayer distance can be obtained by calculating the binding energies as a function of the interlayer distance.It is found that with the adhesion of graphene,graphene/non-Janus MoSSe configuration has the minimum interlayer distance,but the less-stable Janus MoSSe becomes the most stable configuration.Then the energy band structure and Schottky contact of three heterostructures have been studied.The band structure appears to be a simple summation of isolated graphene and(non-)Janus MoSSe,the unique electronic properties of these materials are wellpreserved around the Fermi level.An n-type Schottky contact with the Schottky barrier height(SBH)of 0.38 e V is formed at the equilibrium state for graphene/non-Janus MoSSe,while the n-type SBH for two configurations of graphene/Janus MoSSe is 0.67 and 0.10 e V,respectively.Finally,the modulation by an external electric field applied perpendicularly to the surface on both Schottky barrier height and Schottky contact is investigated.The positive direction of electric field is defined as the same direction pointing from(non-)Janus MoSSe layer to graphene layer.As the strength of electric field increases,the n-type Schottky barrier height increases linearly,and meanwhile the p-type Schottky barrier height decreases.Transition between Ohmic contact and n-type Schottky contact appears when the strength of electric field exceeds-0.2 V/? for graphene/Janus MoSSe,and in graphene/Janus MoSe S,transition between n-type and p-type Schottky contact occurs at0.03 V/?.As for graphene/non-Janus MoSSe,the former type appears at-0.5 V/? while the latter occurs at 0.28 V/?.Therefore,in graphene/non-Janus MoSSe,the transition of n-type,p-type Schottky contact and Ohmic contact can be modulated within a relatively small electric field strength,which is relatively easy to be introduced by experiments,and brings it about great applications potential in optoelectronic and nanoelectronic and devices.