Surface Repair and Passivation of InAs Quantum Wells with ALD

ORAL

Abstract

The two-dimensional electron gas formed in InAs quantum wells and proximitized with epitaxially grown Aluminium has attracted interest as a possible host for Majorana zero modes. This is due to the strong spin-orbit coupling and large Landé g-factor in this material. However, the need to induce superconductivity in the quantum well requires it to be grown close to the surface (~12nm), making the 2DEG highly sensitive to any processing. In particular, the aluminium etch, typically a Transene-based wet etch, has limited measured mobility in InAs quantum wells.

In this work, we report on the use of Al2O3 grown by ALD, with in-situ surface pre-treatment via TMA pulses or an Ar/H plasma, to repair and passivate the surface after processing, and demonstrate the reduction of charged surface states. We show that by this method, we are able to enhance the measured carrier mobility of these devices up to ~45000 cm2/(V s). Finally, the spin orbit length is extracted as a function of density, controlled using a global top-gate, to determine spin-scattering mechanisms. Our results provide a path towards high quality, shallow 2DEG-based Majorana devices.

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Presenters

  • Sebastian Pauka

    School of Physics, The University of Sydney, School of Physics, Univ of Sydney, ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney

Authors

  • Sebastian Pauka

    School of Physics, The University of Sydney, School of Physics, Univ of Sydney, ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney

  • James Witt

    School of Physics, Univ of Sydney

  • Cioffi Nicole Murphy

    Microsoft Station Q Sydney

  • Geoffrey C. Gardner

    Microsoft, Microsoft Quantum at Station Q Purdue, Purdue University, Microsoft Quantum at Station Q Purdue, Purdue University, West Lafayette, Indiana 47907, USA, Microsoft Station Q Purdue, Birck Nanotechnology Center, Purdue University, Department of Physics and Astronomy, Purdue University, Microsoft Quantum at Station Q Purdue, Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA, Purdue University, Station Q Purdue

  • Sergei Gronin

    Microsoft, Microsoft Quantum at Station Q Purdue, Purdue University, Department of Physics and Astronomy, Purdue University, Microsoft Quantum at Station Q Purdue, Purdue University, West Lafayette, Indiana 47907, USA, Microsoft Station Q Purdue, Department of Physics and Astronomy and Station Q Purdue, Purdue University

  • Tian Wang

    Department of Physics and Astronomy and Station Q Purdue, Purdue University, Department of Physics and Astronomy, Purdue University, Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907 USA, Microsoft Station Q Purdue, Birck Nanotechnology Center, Purdue University

  • Candice Thomas

    Microsoft Station Q Purdue, Birck Nanotechnology Center, Purdue University

  • Michael Manfra

    Purdue University, Microsoft, Department of Physics and Astronomy and Station Q Purdue, Purdue University, Department of Physics and Astronomy, Purdue University, Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907 USA, Microsoft Station Q Purdue, Physics and Astronomy, Purdue University, Department of Physics and Astronomy, School of Materials Engineering and School of Electrical and Computer Engineering, Purdue University, Station Q Purdue and Department of Physics and Astronomy, Purdue University, Dept. of Physics, Purdue University, Department of Physics and Astronomy and Station Q Purdue, Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA, Dept. of Physics and Astronomy, Purdue, Purdue University, Station Q Purdue, Department of Physics and Astronomy, Station Q Purdue, and Birck Nanotechnology Center, Purdue University

  • David Reilly

    Microsoft Corporation Sydney, Microsoft Station Q Sydney

  • Maja C Cassidy

    Microsoft Corporation Sydney, Microsoft Station Q Sydney