Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 13: Electronic Structure of Surfaces II

O 13.3: Vortrag

Montag, 16. März 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. Schneider¹ — ¹Forschungszentrum 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.