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TY - THES AU - Janßen, Kevin TI - Fabrication and characterization of single interfaces of Niobium and selectively molecular beam epitaxy grown (Bi<sub>1−x</sub>Sb<sub>x</sub>)<sub>2</sub>Te<sub>3</sub> nanoribbons PB - RWTH Aachen University VL - Dissertation CY - Aachen M1 - RWTH-2024-04651 SP - 1 Online-Ressource : Illustrationen PY - 2024 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University N1 - Dissertation, RWTH Aachen University, 2024 AB - In the scope of this thesis a comprehensive differential conductance analysis of in-situ and ex-situ fabricated single interfaces of niobium and selective-area molecular beam epitaxy grown (Bi1-xSbx)2Te3 ribbons with widths ranging from 100 nm - 300 nm has been carried out. For the in-situ single interfaces a new fabrication process has been developed which utilizes shadow mask evaporation and selective-area molecular beam epitaxy. The resulting interfaces show a high transparency which leads to a zero bias conductance increase of 1.7 compared to the normal state conductance, originating from a large contribution of Andreev reflection at the interface. The spectra have been compared with the Blonder-Tinkham-Klapwijk model and a density functional theory analysis. Furthermore, the temperature, perpendicular magnetic field, and top gate dependence of the differential conductance spectrum has been investigated in order to achieve a comprehensive overview of the interface physics. In addition to that, the differential conductance of the (Bi1-xSbx)2Te3 ribbon itself has been analyzed. The ex-situ interfaces have been fabricated by a conventional lift-off procedure with and without argon-milling before the niobium deposition. The differential conductance has been investigated for different temperatures and perpendicular magnetic fields. The resulting zero bias conductance peak and sharp conductance dips in the spectrum can be related to the critical current in the disordered interface region and do not originate from a high contribution of Andreev reflection at the interface. LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2024-04651 UR - https://publications.rwth-aachen.de/record/985491 ER -