Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 30: Poster I
HL 30.35: Poster
Tuesday, March 17, 2020, 13:30–15:45, P3
Topological insulator nanowires grown selectively by molecular beam epitaxy — •Gertjan Lippertz1,2, Andrea Bliesener1, Anjana Uday1, Gian-Luca Ansermetti1, Oliver Breunig1, Alexey Taskin1, Lino Pereira2, and Yoichi Ando1 — 1Physics Institute II, University of Cologne, Germany — 2Quantum Solid State Physics, KU Leuven, Belgium
Inducing superconductivity into a topological insulator (TI) nanowire by proximitizing it with an s-wave superconductor is predicted to give rise to Majorana bound states. However, TI nanowires grown by the Vapor-Liquid-Solid (VLS) technique are difficult to integrate into scalable device structures. Therefore, we are pursuing an alternative route towards nanowire structures, selective-area growth (SAG) by molecular beam epitaxy (MBE). A Si3N4 layer is deposited on a sapphire substrate and patterned into nanowire devices using electron-beam lithography and reactive ion etching. Within a small parameter range, (Bi1−xSbx)2Te3 can be selectively grown by MBE inside the trenches of the pre-patterned substrate. Control over the chemical potential of the nanowires is achieved by a side-gate fabricated in the same process, alleviating the need for additional fabrication steps after growth.
In this presentation, we show our first results towards growing bulk-insulating TI nanowires with a width below 100 nm. Such SAG-TI nanowires are expected to show non-equidistant resistance peaks as a function of the gate voltage, which was recently shown to be the unique signature of quantum-confined Dirac surface states.