Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 21: [MA] Joint Session "Topological Insulators I" (jointly with DS, HL, O, TT)
O 21.4: Vortrag
Montag, 26. März 2012, 18:30–18:45, H 1012
Reactive chemical doping of the Bi2Se3 topological insulator — •Hadj Mohamed Benia, Chengtian Lin, Klaus Kern, and Christian R. Ast — Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany
We studied the evolution of the surface electronic structure of the topological insulator Bi2Se3 as a function of water vapor exposure using angle resolved photoemission spectroscopy. We find that a surface reaction with water induces a band bending, which shifts the Dirac point deep into the occupied states and creates 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 Bi2Se3 crystals are left in vacuum or cleaved in air, which likely explains the aging effect observed in the Bi2Se3 band structure.