Wafer Bonding Approach for Epitaxial Al/GaAs(001)/Al Tri-layers

ORAL

Abstract

Superconductor-insulator-superconductor (Josephson) junctions utilizing amorphous oxide barriers have been studied extensively, however relatively little work has been done using single crystal semiconductors in place of amorphous oxide barriers. This is likely due to difficulty in fabrication of such structures including symmetry mismatch of the semiconductor to the superconductor and the reactions and roughening that may occur at the temperatures needed for semiconductor growth. This work focuses on a wafer bonding approach, subsequent substrate removal, and superconductor regrowth for fabrication of Al/GaAs(001)/Al Josephson junctions. AlGaAs/GaAs/Al structures are grown by molecular beam epitaxy and wafer-bonded to Si. The substrate and sacrificial AlGaAs layers were removed by selective wet etching followed by surface cleaning in ultrahigh vacuum and aluminum regrowth. The wafer bond and Al/GaAs interfaces are studied by transmission electron microscopy . X-ray photoelectron microscopy is used to determine GaAs surface cleaning conditions compatible with the wafer bonding process following substrate removal. X-ray and electron diffraction are used to assess crystalline quality and orientation of the epitaxial aluminum.

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Presenters

  • Anthony McFadden

    University of California, Santa Barbara, ECE and Materials, University of California, Santa Barbara, University of California Santa Barbara

Authors

  • Anthony McFadden

    University of California, Santa Barbara, ECE and Materials, University of California, Santa Barbara, University of California Santa Barbara

  • Corey Rae McRae

    National Institute of Standards and Technology (NIST), Boulder

  • Russell Lake

    National Institute of Standards and Technology (NIST), Boulder, Boulder, NIST, National Institute of Standards and Technology Boulder, National Institute of Standards and Technology, Boulder

  • Michael A Seas

    University of California, Santa Barbara, University of Wyoming

  • Jianguo Wen

    Center for Nanoscale Materials, Argonne National Laboratory, Argonne National Laboratory

  • Jie Wang

    Center for Nanoscale Materials, Argonne National Laboratory, Argonne National Laboratory

  • Ilke Arslan

    Center for Nanoscale Materials, Argonne National Laboratory, Argonne National Laboratory

  • David Pappas

    National Institute of Standards and Technology (NIST), Boulder, Quantum Devices, NIST-Boulder, National Institute of Standards and Technology Boulder, NIST, Boulder, Colorado, National Institute of Standards and Technology, Boulder

  • Chris Palmstrom

    University of California, Santa Barbara, University of California - Santa Barbara, University of California Santa Barbara, Electrical & Computer Engineering, University of California, Santa Barbara, ECE and Materials, University of California, Santa Barbara, Dept. of ECE, University of California Santa Barbara, Materials Department, University of California, Santa Barbara, Materials Engineering, University of California, Santa Barbara, University of California Santa Barbara, Materials Engineering, Departments of Electrical and Computer Engineering and Materials, University of California, Santa Barbara