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Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 13: Electronic Structure of Surfaces II

O 13.3: Talk

Monday, March 16, 2015, 15:45–16:00, MA 041

Epitaxial Sb2Te3 / Bi2Te3 heterostructures: a new (route to) topological p-n junction — •Markus Eschbach1, Ewa Mlynczak1, Jens Kellner2, Jörn Kampmeier1, Martin Lanius1, Christian Weyrich1, Gregor Mussler1, Natalya Demarina1, Thomas Schäpers1, Lukasz Plucinski1, Detlev Grützmacher1, Markus Morgenstern2, and Claus M. Schneider11Forschungszentrum Jülich GmbH, Peter Grünberg Institut, 52425 Jülich, Germany — 2II. Physikalisches Institut B, RWTH Aachen University, 52074 Aachen, Germany

Recently, in the field of 3D Topological Insulators various attempts have been carried out to tune the chemical potential and, more specifically, the Dirac point to a desired energetic position i.e. to engineer the electronic bandstructure for the purpose of designing future spintronic devices. Here we show the first direct experimental proof, by angle-resolved photoemission, of the realization of a topological p-n junction made of a heterostructure of two different 3D TI materials Bi2Te3 and Sb2Te3 grown on Si(111). In the experiment we observe an energetic shift of the entire electronic structure of about 200 meV when decreasing the upper Sb2Te3 layer from a thickness of 25 QL to 6 QL. On one hand, we consider surface doping and the creation of a ternary alloy at the surface and on the other hand the creation of a depletion region and a built-in electric field at the interface of the two TI materials to be responsible for the shift. The latter contribution is supported by solving Schrödinger and Poisson equations self-consistently for a 1D model system.

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