Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 50: HL Poster IV

HL 50.25: Poster

Thursday, March 15, 2018, 19:00–21:00, Poster B

Growth and Electrical Characterization of (Bi_1−xSb_x)₂Te₃ Topological Insulator Nanoribbons — •Dingxun Fan, Matthias Rössler, Zhiwei Wang, Oliver Breunig, Fan Yang, Alexey Taskin, and Yoichi Ando — II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany

Surface states of topological insulator (TI) nanoribbons, when proximitized by s-wave superconductors, are expected to realize topological superconducting phases harbouring Majorana bound states (MBS) at the ends. MBS platform based on TI nanoribbons has the advantage of a wide parameter range in terms of the chemical potential and magnetic field, resulting from the inherent property of spin-momentum locking. However, the experimental progress is largely hindered by bulk conduction. As a first step, it is desired to grow bulk-insulating TI nanoribbons where the bulk contribution is minimized while preserving circumferential quantization from quasi-1D band structure.

Here we study the growth of ternary (Bi_1−xSb_x)₂Te₃ nanoribbons by a Au-catalysed VLS method in a tube furnace. High quality Bi₂Te₃ and Sb₂Te₃ powders prepared by crushing lab-grown single crystals are placed at different temperatures in an Ar gas flow. By tuning the growth temperature and flow rate, very thin (Bi_1−xSb_x)₂Te₃ nanoribbons down to ∼20 nm in width and thickness and up to ∼10 um in length can be achieved. The composition of the nanoribbons is determined by electron diffraction spectroscopy. Subsequent nanofabrication is also carried out to characterize the electrical properties of these nanoribbons.