title: Rapid surface oxidation as a source of surface degradation factor for Bi₂Se₃.
abstract: Bismuth selenide (Bi(2)Se(3)) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi(2)Se(3) is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi(2)Se(3) gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi(2)Se(3) nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi(2)Se(3) under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi(2)Se(3) by transport measurements.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
authors.forename: Desheng
authors.initials: D
authors.lastname: Kong
authors.forename: Judy J
authors.initials: JJ
authors.lastname: Cha
authors.forename: Keji
authors.initials: K
authors.lastname: Lai
authors.forename: Hailin
authors.initials: H
authors.lastname: Peng
authors.forename: James G
authors.initials: JG
authors.lastname: Analytis
authors.forename: Stefan
authors.initials: S
authors.lastname: Meister
authors.forename: Yulin
authors.initials: Y
authors.lastname: Chen
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Zhang
authors.forename: Ian R
authors.initials: IR
authors.lastname: Fisher
authors.forename: Zhi-Xun
authors.initials: ZX
authors.lastname: Shen
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui