Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3

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• 作者：Desheng Kong ; Judy J. Cha ; Keji Lai ; Hailin Peng ; James G. Analytis ; Stefan Meister ; Yulin Chen ; Hai-Jun Zhang ; Ian R. Fisher ; Zhi-Xun Shen ; Yi Cui
• 刊名：ACS Nano
• 出版年：2011
• 出版时间：June 28, 2011
• 年：2011
• 卷：5
• 期：6
• 页码：4698-4703
• 全文大小：895K
• 年卷期：0
• ISSN：1936-086X

文摘

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.