First-principles Study On The Band Structure Engineering Of Topological Insulator Bi₂Se₃ Family

The interest of topological insulators(TIs)is to a large extent driven by the exotic surface electronic properties and the anticipated numerous potential applications in semiconductor spintronics.The gapless topological SSs of TIs,which is protected by time-reversal symmetry(TRS),also contribute to the development of theoretical and experimental investigations.Bi2Se3 and Bi2Te3 are two of the hottest topological insulator materials.Their bulk energy band gaps are far beyond the room temperature scale,which make them have a good prospect in the use of quantum devices.However,there are still a large number of defects in the process of the production which makes the transport properties of their surface states difficult to be used.Therefore,taking control by simulation,not only for spintronics and topological insulator device has a very important significance,but also provide a theoretical basis for the research on the experiment the.In this paper,we performed a first-principles calculation within density functional theory(DFT)to investigate several popular TIs films,including Bi2Se3,Bi2Te3,Cr-doped Bi2Se3 and Bi2(SexTe1-x)3.Our main purpose is to achieve the simulating of the electronic structures by magnetic doping,applied stress and applied electric field.We use the VASP package to calculate the band structure,density of states,average planar electrostatic potentials and electron density.We analyzed these results to find out the mechanism of the influence of different external fields on the materials.