Vacancy Defect Scattering In Ag(111)-supported Silicene With Spin–orbit Coupling

Monolayer materials provide us with the most active field in two-dimensional electronic systems.The success of graphene has led to extensive research into other monolayers.Graphene,a flat sheet of hexagonal carbon atoms,has attracted much attention in recent years because of its unique physical,chemical and mechanical properties.Theory predicts that graphene's monolayer honeycomb structure can be obtained from other IV elements.One of the most interesting materials is silicene,a silicon analogue of graphene,which may have promising technical applications because of its compatibility with existing electronic infrastructure.Due to its similar lattice structure,it has similar electron band structure with graphene,and due to its special low-buckled structure,silicene has quantum spin hall effect and electrically modulated band gap.This also makes silicene one of the most promising new materials in silicon atom nanotechnology.In this master thesis,the research progress of the electronic and topological properties of graphene and other analogue 2D materials is briefly described.Starting from the description of the topological properties of the general Dirac electronic system,it is applied to the silicene by introducing vacancy and spin.Based on them,the scattering of vacancy defects in the electron mobility of 2D silicene on Ag(111)substrate was studied.The structure of silicene-silver substrate interface and the effect of silicene surface charge density on electron mobility are discussed.In addition,based on the strong spin orbit coupling effect of silicene and the inevitable defect structure under the current experimental conditions,we introduce the influence of electrostatic potential and applied electric field of vacancy defect charge.The effect of spin orbit coupling correction on electron scattering from vacancy defect is analyzed in detail,and the carrier mobility near the interface between silicene and silver substrate is calculated carefully.The results show that the influence of vacancy defect on electron mobility depends on energy,vacancy density,vacuum thickness and vertical external electric field strength.The mobility limited by the vacancy defect of the silicene substrate is kept within the range of10~2-10~5cm~2/V?s.The method in this thesis provides a valuable scientific method for predicting the mobility of other two-dimensional graphene-like materials.