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

TL;DR

This paper investigates how rapid surface oxidation of Bi2Se3 nanoribbons causes surface degradation, affecting topological surface states, and highlights the need for surface passivation to preserve these states for transport measurements.

Contribution

It provides experimental evidence linking surface oxidation to degradation of topological surface states in Bi2Se3, emphasizing the importance of surface passivation.

Findings

Native oxide forms rapidly on Bi2Se3 in ambient conditions

Surface oxidation induces n-type doping at the surface

Oxidation likely causes degradation of topological surface states

Abstract

Bi2Se3 is a topological insulator with metallic surface states residing in a large bulk bandgap. It is believed that Bi2Se3 gets additional n-type doping after exposure to atmosphere, thereby reducing the relative contribution of surface states in total conductivity. In this letter, 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 surface states. Appropriate surface passivation or encapsulation may be required to probe topological surface states of Bi2Se3 by transport measurements.