First-Principles Investigation on Electronic Structure of Bi 2 Se 3 Thin Film and the Films Doped with Pb

Abstract First-principles calculations were performed to investigate the electronic structure of the Bi 2 Se 3 single quintuple layer thin film and the films doped with Pb. Their band structures and densities of states were explored. The results show that the main composition of the valence band and conduction band of these films is p-states, and their band-gap type can change from the direct to the indirect as Bi 2 Se 3 from block to film. For the BiPbSe 3 film, the newly appearing Se(1′) layer in its structure caused by the doped Pb has an impact on the electronic structures of the film, but for the Pb 0.25 Bi 1.75 Se 3 thin film with the concentration of Pb ∼5%, it has the similar band structure to the pristine film. This paper also discussed the modulation of Bi 6s orbital states at the valence band maximum and the concentration of carriers in doped films