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

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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

Fingerprint

Molecular beam epitaxy
Lithography
Superconducting materials
lithography
insulators
Thin films
Surface states
thin films
Transparency
Oxides
Ion beams
Masks
Electron microscopes
Deposits
SIS (superconductors)
Degradation
Air
molecular beam epitaxy
masks
electron microscopes

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
Schüffelgen, Peter ; Rosenbach, Daniel ; Neumann, Elmar ; Stehno, Martin P. ; Lanius, Martin ; Zhao, Jialin ; Wang, Meng ; Sheehan, Brendan ; Schmidt, Michael ; Gao, Bo ; Brinkman, Alexander ; Mussler, Gregor ; Schäpers, Thomas ; Grützmacher, Detlev. / Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films. In: Journal of crystal growth. 2017 ; Vol. 477. pp. 183-187.
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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.",
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Schüffelgen, P, Rosenbach, D, Neumann, E, Stehno, MP, Lanius, M, Zhao, J, Wang, M, Sheehan, B, Schmidt, M, Gao, B, Brinkman, A, Mussler, G, Schäpers, T & Grützmacher, D 2017, 'Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films' Journal of crystal growth, vol. 477, pp. 183-187. https://doi.org/10.1016/j.jcrysgro.2017.03.035

Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films. / Schüffelgen, Peter; Rosenbach, Daniel; Neumann, Elmar; Stehno, Martin P.; Lanius, Martin; Zhao, Jialin; Wang, Meng; Sheehan, Brendan; Schmidt, Michael; Gao, Bo; Brinkman, Alexander; Mussler, Gregor; Schäpers, Thomas; Grützmacher, Detlev.

In: Journal of crystal growth, Vol. 477, 01.11.2017, p. 183-187.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films

AU - Schüffelgen, Peter

AU - Rosenbach, Daniel

AU - Neumann, Elmar

AU - Stehno, Martin P.

AU - Lanius, Martin

AU - Zhao, Jialin

AU - Wang, Meng

AU - Sheehan, Brendan

AU - Schmidt, Michael

AU - Gao, Bo

AU - Brinkman, Alexander

AU - Mussler, Gregor

AU - Schäpers, Thomas

AU - Grützmacher, Detlev

PY - 2017/11/1

Y1 - 2017/11/1

N2 - 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.

AB - 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.

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KW - A1. Stencil lithography

KW - A3. Molecular beam epitaxy

KW - B2. Superconductor

KW - B2. Topological insulator

KW - B3. Josephson junction

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U2 - 10.1016/j.jcrysgro.2017.03.035

DO - 10.1016/j.jcrysgro.2017.03.035

M3 - Article

VL - 477

SP - 183

EP - 187

JO - Journal of crystal growth

JF - Journal of crystal growth

SN - 0022-0248

ER -