Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 47: Electronic Structure of Surfaces: Spectroscopy, Surface States

O 47.14: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Alpha-Sn: doping and Te coating study — •Caroline von Andrian-Werburg, Markus Scholz, Felix Reis, Victor Rogalev, Ralph Claessen, and Jörg Schäfer — Physikalisches Institut, Universität Würzburg, 97074 Würzburg, Germany

Topological insulators (TIs) promise an outstanding progress in transformation of conventional electronics to spintronics. In that scope mono-elemental 3D TIs would have a significant advantage due to the simplicity of growth and defect control. However, the only example described so far is the low temperature phase of Sn (α-Sn) [1]. Recently it was found that using Molecular Beam Epitaxy one can stabilize the low-T phase of Sn with topological character on a substrate with a slightly mismatched lattice (0, 14%)[2]. This compressive strain induces a gap at the Fermi level of the otherwise gapless α-Sn with band inversion, thus enabling the occurrence of the topological surface states. In the current study we explore further important steps towards the technological application of α-Sn, namely, the possibility of doping to vary the position of the Fermi level and protective capping of the film. The protective layer is required in case of ex-situ transfer operations. For both purposes we find elemental Te to be a suitable candidate. A small amount of the Te during the co-deposition with Sn allows to introduce a n-doping of the material, while the amorphous Te overlayer protects the surface from the unnecessary contamination and can be removed by moderate annealing.

[1] L. Fu and C. L. Kane, Phys. Rev. B. 76, 045302 (2007).

[2] A. Barfuss et al., Phys. Rev. Lett. 111, 157205 (2013).