Research On The Electron Properties Of Two-dimensional Heterostructures Based On Graphene

Since 2004,monolayer graphene has been successfully prepared by mechanical stripping.Twodimensional materials(2D)attract much attention researchers due to their excellent physical and chemical properties.Metal chalcogenides are layered materials with hexagonal honeycomb structure and A-B-B-A atomic stack.Because of its unique structure and novel properties,researchers have been attracted to study metal chalcogenides.Unlike graphene,metal chalcogenides have moderate band gaps.Which makes it widely used in optoelectronic devices,biocatalysis,sensors.In order to solve the limitation of the properties of single 2D layered materials,different advanced 2D materials are combined to form 2D heterostructures.Based on the first principle methods,the structures and related electronic properties of the heterostructure formed by the metal chalcogenides and graphene are studied.The heterostructures of Ga Te/graphene and In Te/graphene are designed.Several stacking methods of two heterostructures are studied,and the lowest energy and most stable stacking methods are selected.In the following calculation,the most stable stacking structures are used to explore the electronic properties of heterostructures.Firstly,the binding energies of heterostructures are calculated and analyzed.Secondly,the electrostatic potential energy and surface difference charge density of heterostructures are calculated,and the electric field and charge transfer between layers are analyzed.Finally,the effects of layer spacing and applied vertical electric field on the schottky barrier height and the transformation of schottky contact types are investigated.In this paper,the structures are stable by calculating the binding energy of heterogeneous structures.The electronic structure of Ga Te/graphene and In Te/graphene heterostructures arecalculated,which results suggest that the electronic properties of Ga Te and graphene monolayers,In Te and graphene monolayers are well preserved in the heterostructures of Ga Te/graphene and In Te/graphene and p-type schottky contacts are formed in the equilibrium of heterostructures.It is also noted that the band gaps of graphene in both heterostructures are opened by tens of millivolt.It can be concluded from the electrostatic potential energy and differential charge that there is a large electrostatic potential energy difference between the semiconductor and the graphene interface in these two heterostructures and the charge is transferred from the graphene to the semiconductor.By adjusting the interlayer distance of heterogeneous structures or applying a vertical electric field,it is found that the Fermi energy levels of Ga Te and In Te monolayers move up and down in the heterostructures,resulting in the transformation of the barrier height and the contact type of these two heterostructures.Both methods can sensitively adjust the schottky barrier height and schottky contact type of heterogeneous structures.It is hoped that these results can provide effective help for the design and experiment of materials in the future.