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arXiv · 1105.2664

Reactive chemical doping of the $Bi_2 Se_3$ topological insulator

Hadj M. Benia·Chengtian Lin·Klaus Kern·Christian R. Ast
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Abstract

Using angle resolved photoemission spectroscopy we studied the evolution of the surface electronic structure of the topological insulator $\text{Bi}_2\text{Se}_3$ as a function of water vapor exposure. We find that a surface reaction with water induces a band bending shifting the Dirac point deep into the occupied states and creating quantum well states with a strong Rashba-type splitting. The surface is thus not chemically inert, but the topological state remains protected. The band bending is traced back to Se-abstraction leaving positively charged vacancies at the surface. Due to the presence of water vapor, a similar effect takes place when $\text{Bi}_2\text{Se}_3$ crystals are left in vacuum or cleaved in air, which likely explains the aging effect observed in the $\text{Bi}_2\text{Se}_3$ band structure.

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Hadj M. Benia, Chengtian Lin, Klaus Kern, Christian R. Ast. 2011-05-13. Reactive chemical doping of the $Bi_2 Se_3$ topological insulator. https://doi.org/10.1103/physrevlett.107.177602

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