SKM 2021 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 4: Poster

DS 4.15: Poster

Dienstag, 28. September 2021, 10:00–13:00, P

Selective Area Epitaxy of Bi-based 3D Topological Insulators on Sapphire — •Christoph Ringkamp, Michael Schleenvoigt, Peter Schüffelgen, Gregor Mussler, and Detlev Grützmacher — Peter-Grünberg-Institut 9, Forschungszentrum Jülich, 52428 Jülich, Germany

Topological insulators (TI) possess topologically protected, conducting surface states, which – in conjunction with superconductors (SC), are predicted to show Majorana signatures. 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). 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.

We will report on the selective area epitaxy via MBE of Bi-based TI like Bi2Te3 and Bi2Se3 on sapphire substrates that are prepared with a combination of lithographically defined SiO2 and Si3N4 structures as a growth mask and their application as a shadow mask for TI/SC heterostructures. Additionally, I will show a substantial improvement of the carrier mobility in the TI films on sapphire compared to Si(111).