Effect Of Charging On Silicene With Alkai Metal Atom Adsorption

Having similar honeycomb structure,silicene also possesses many properties of graphene,such as massless Dirac fermions,Dirac cone,gapless band structure and high carrier mobility.Dissimilarly,the band gap of silicene can be opened by the interface interaction between silicene and substrate,external vertical electronic field and the surface adsorption.Especially,the adsorption of alkali metal(AM)atoms on silicene can make silicene open a band gap without degrading its high carrier mobility.According to previous studies,the silicene with AM atoms adsorption can be used as the channel of a high-performance field effect transistor(FET).In addition,silicene has been used as the anode materials for Li-ion and Na-ion batteries.However,whether being applied in FET or in Li-ion and Na-ion batteries,silicene with AM atoms adsorption is not electrically neutral.Therefore,the effect of charging on silicene with AM atoms adsorption may be helpful for its application in modern electronic industry.In this thesis,based on the first-principles calculations,we studied the effects of charging on structure,binding energy and electronic property of silicene with AM atoms adsorption.We also studied the distribution of the doping charge.In chapter 1,a briefly introduction of silicene from preparation and application is presented.In chapter 2,we have a general review of the various techniques,including density functional theory,exchange association functional,energy band theory,the Vienna Ab-inito Simulation Package and the details of computational in this thesis.In chapter 3,we studied the effects of charging on structure,binding energy and electronic property of silicene with AM atoms adsorption.The results show that electron doping mainly affects the structure of the system,while hole doping mainly affects the AM-Si vertical distance and the binding energy.When the hole doping is as large as +e per unit cell,although the system is semiconductor,dense AM atoms may be unstable on silicene.In the system of 12.5% adsorption concentration,only the band gap of silicene with potassium atoms adsorption is not so sensitive to the charge doping and the AM-Si vertical distance,which may be more practicable in nanotechnology.In chapter 4,we studied the distribution of the doping charge in charged systems.The complex AM–Si interaction,including electrostatic and covalent effects,may be the main reason for the complex change of the structure and the binding energy in charged systems.The finale chapter is a brief summary of this thesis.