Study On Tunning Of Electronic Structure In Graphene-based Van Der Waals Heterostructures

Since 2004,British scientist Andrei Gem and Constantine Novo Shawlov succeeded instripping out of graphene from graphite.Graphene has become the most promising the two-dimensiona nanomaterials of the 21 st century,because of its unique physical and chemical properties,such as quantum tunneling,oversized theoretical area,excellent electrical properties and high electron mobility and high Young's modulus.However,two-dimensiona graphene material is not perfect,there are some problems in practical applications need to be resolved.In the case of graphene,graphene has an extremely high electron mobility,but its bandgap is zero,which limits its application in electronic device engineering.In this paper,we use the first-principles method of density functional theory to analyze the tunning of electronic structure of graphene and arsenene,graphene and Sn S2 van der Waals heterostructures,As follows:Firistly,study on tunning of electronic structure in the van der Waals heterostructures of arsenene and graphene.First of all,as a basic parameter,the lattice parameters and electric structures of graphene and arsenene were studied.Based on this,the van der Waals heterostructures of arsenene and graphene was constructed.The results show,the positions of Dirac point and fermi level shift from the valence band maximum(VBM)to conduction band minimum(CBM)of arsenene as the conduction band to the valence,the p-type Schottky barrier to n-type Schttky barrier transition occurs when the interlayer distance increases from 2.8 to 4.5 ?.Through further analysis,we found that varying the interlayer distance between the arsenene and graphene heterostructures can tunne the Schottky barrier height of the Schottky contact.In addition,we also construct a symmetrical three-layer graphene and arsenene van der Waals heterostructures structure,and the electronic structure and the effects of electronic field on the electronic structure of the van der Waals heterostructures was simply analyzed.The calculated results show that the charge in the three-layer heterostructures is transferred from arsenene to graphene and rearranged at the interface.Simultaneously,the Schottky barrier of the heterostructures have not obviously changing for the tunning of the electric field,indicating that the Schottky contact of the symmetric three-layer heterostructures is insensitive for the electricfield.Secondly,study on tunning of electronic structure in the van der Waals heterostructures of graphene and Sn S2,The calculated results show,interlaye distance and electron field can effectively tune the electronic structure of heterostructures.When the interlayer distance of heterostructures increases(2.5?~4.4?),the height of the Schottky barrier have a slightly reduction,basically remain the same.which is consistent with relating to van der Waals Force effect.Under the effect of the electric field,when the negative electric field is applied,the Dirac point of graphene and fermi level moves to the valence band of Sn S2 form the conduction band,and the barrier height also have a slightly increasing.When the positive electric field is applied,the Dirac points of graphene and fermi level enter the conduction band of Sn S2,form an ohmic contact.