Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 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 Bi2Se3 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 Bi2Se3 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 Bi2Se3 by transport measurements. © 2011 American Chemical Society.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-I1-001-12, KLIS-F1-033-02
Acknowledgements: Y.C. acknowledges the supported from the Keck Foundation and King Abdullah University of Science and Technology (KAUST) Investigator Award (No. KUS-I1-001-12). K.L. acknowledges the KAUST Postdoctoral Fellowship support No. KLIS-F1-033-02. J.G.A. and I.R.F. acknowledge support from the Department of Energy, Office of Basic Energy Sciences, under contract DE-AC02-76SF00515.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.