The Properties Of Electrons Transport Through The Step Barrier On The Surface Of The Topological Insulator

Recently, the research of topological insulators has become focus in the field of condensedmatter physics. It is a kind of new material that has a energy gap in the bulk such as that inordinary insulators and gapless helical edge or metallic surface states on the boundary,which depends on the topology of the electronic state. Moreover, the electron in thesurface possess linear dispersion relation. Topological insulators have attracted increasingattentions due to its unique band structure and the special properties of massless Dimefermion. It is expected that the metallic state of the surface or boundary is observed and itspractical application is explored. The special physical properties of these new materialshave a significant impact for the quantum computing and the spintronics, etc.In this paper, we study the properties of the electronic transport through the stepbarrier on the surface of topological insulator. We starting from the Dirac equationanalyzed the wave function of the step barrier on the surface of topological insulator, andcalculated the the probabilities of the transmission and conductance of the step barrier. Wefound that the number of resonance peaks in the transmission about the surface oftopological insulator related to the barrier width, the wider the barrier, the more thenumber of peaks. We also found that the transmission probability of the surface oftopological insulator determined by the height of the barrier and there exist Kleintunneling. We calculated the conductance in the step barrier using the transfer matrixtheory and the formula of Landauer-Buttiker. We found that there exist the resonanttunneling phenomena. As the difference between the high and low potentials of the stepbarrier changes, the conductance exists the switch effect. Therefore we can control theconductance by adjusting the Fermi level and the difference between the high and lowpotential of the step barrier.