Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films

Peter Schüffelgen*, Daniel Rosenbach, Elmar Neumann, Martin P. Stehno, Martin Lanius, Jialin Zhao, Meng Wang, Brendan Sheehan, Michael Schmidt, Bo Gao, Alexander Brinkman, Gregor Mussler, Thomas Schäpers, Detlev Grützmacher

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Topological insulator (Bi0.06Sb0.94)2Te3 thin films grown by molecular beam epitaxy have been capped in-situ with a 2 nm Al film to conserve the pristine topological surface states. Subsequently, a shadow mask - structured by means of focus ion beam - was in-situ placed underneath the sample to deposit a thick layer of Al on well-defined microscopically small areas. The 2 nm thin Al layer fully oxidizes after exposure to air and in this way protects the TI surface from degradation. The thick Al layer remains metallic underneath a 3–4 nm thick native oxide layer and therefore serves as (super-) conducting contacts. Superconductor-Topological Insulator-Superconductor junctions with lateral dimensions in the nm range have then been fabricated via an alternative stencil lithography technique. Despite the in-situ deposition, transport measurements and transmission electron microscope analysis indicate a low transparency, due to an intermixed region at the interface between topological insulator thin film and metallic Al.

Original languageEnglish
Pages (from-to)183-187
Number of pages5
JournalJournal of crystal growth
Volume477
DOIs
Publication statusPublished - 1 Nov 2017

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Keywords

  • A1. Shadow mask
  • A1. Stencil lithography
  • A3. Molecular beam epitaxy
  • B2. Superconductor
  • B2. Topological insulator
  • B3. Josephson junction

Cite this

Schüffelgen, P., Rosenbach, D., Neumann, E., Stehno, M. P., Lanius, M., Zhao, J., ... Grützmacher, D. (2017). Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films. Journal of crystal growth, 477, 183-187. https://doi.org/10.1016/j.jcrysgro.2017.03.035