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O: Fachverband Oberflächenphysik

O 122: Topology and Symmetry Protected Materials II

O 122.10: Vortrag

Freitag, 20. März 2020, 12:45–13:00, WIL A317

MBE Growth of 3D Topological Insulators on Sapphire — •Christoph Ringkamp, Gregor Mussler, and Detlev Grützmacher — PGI-9, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Germany

Topological insulators (TI) possess topologically protected, conducting surface states, which are predicted to show Majorana signatures in conjunction with superconductors (SC). A prerequisite for this is a high transparency between the TI and the SC, and that is why an in-situ fabrication of the TI/SC heterostructures is crucial. On Si(111) substrates, we have already established the selective area growth and a shadow mask technique to fabricate such heterostructures via molecular-beam epitaxy (MBE) [1]. However, one major problem in transport experiments still poses the impact of the Si substrate, as the Si/TI interface may serve as an additional conducting channel. Hence, we intend to grow the TI/SC heterostructures on sapphire, as it is a purely insulating substrate which may allow to investigate the topological properties of the TI films in transport experiments in more detail.

I will report on the MBE growth of Bi2Te3, Bi2Se3, Sb2Te3 and its alloys on sapphire substrates, and I will show a substantial reduction of crystal defects in the TI films on sapphire compared to Si(111). Furthermore, I will present first results of selective area growth of TIs on sapphire, using a combination of lithographically defined SiO2 and Si3N4 structures as a growth mask.

[1] Schüffelgen et al., Nature Nanotechnology 14, 825 (2019)