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  • Open Access

Enhancement of proximity-induced superconductivity in a planar Ge hole gas

Kushagra Aggarwal1,*, Andrea Hofmann1, Daniel Jirovec1, Ivan Prieto1, Amir Sammak2, Marc Botifoll3, Sara Martí-Sánchez3, Menno Veldhorst4, Jordi Arbiol3,5 et al.

Giordano Scappucci4, Jeroen Danon6, and Georgios Katsaros1,†

  • 1Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
  • 2QuTech and Netherlands Organisation for Applied Scientific Research (TNO), Stieltjesweg 1, 2628 CK Delft, The Netherlands
  • 3Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Bellaterra, Barcelona, Catalonia, Spain
  • 4QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
  • 5ICREA, Pg. Llus Companys 23, 08010 Barcelona, Catalonia, Spain
  • 6Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway

  • *kushagra.aggarwal@ist.ac.at
  • †georgios.katsaros@ist.ac.at
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Phys. Rev. Research 3, L022005 – Published 15 April, 2021

DOI: https://doi.org/10.1103/PhysRevResearch.3.L022005

Abstract

Hole gases in planar germanium can have high mobilities in combination with strong spin-orbit interaction and electrically tunable g factors, and are therefore emerging as a promising platform for creating hybrid superconductor-semiconductor devices. A key challenge towards hybrid Ge-based quantum technologies is the design of high-quality interfaces and superconducting contacts that are robust against magnetic fields. In this work, by combining the assets of aluminum, which provides good contact to the Ge, and niobium, which has a significant superconducting gap, we demonstrate highly transparent low-disordered JoFETs with relatively large ICRN products that are capable of withstanding high magnetic fields. We furthermore demonstrate the ability of phase-biasing individual JoFETs, opening up an avenue to explore topological superconductivity in planar Ge. The persistence of superconductivity in the reported hybrid devices beyond 1.8 T paves the way towards integrating spin qubits and proximity-induced superconductivity on the same chip.

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Phys. Rev. Research 3, L022005– Published 15 April, 2021
  • Received 10 November 2020
  • Revised 23 March 2021
  • Accepted 24 March 2021
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