Effects of an external electric field on electronic states and transport of a Bi2Se3 thin film

We study the electronic band structure, density distribution, and electronic transport of surface states in a Bi2Se3 thin film. By using the four-band model, it is demonstrated that an appropriate external electric field can eliminate the coupling between the top and bottom surface states of the film, and contribute to the realization of the quantum spin Hall effects. However, a sufficient high electric field may destroy the property of the surface states. Using the scattering matrix approach, we further study theoretically the spin-dependent electron transport of a Bi2Se3 thin-film junction. Interestingly, a transverse electric field can switch on/off the spin-up or -down electronic channel of the surface states in the junction.