Surfaces, Interfaces, and Impurity Elements in Niobium-based Materials for Superconducting Quantum Computing Analyzed by Atom-Probe Tomography

ORAL

Abstract

Superconductivity with Tc=9.3 K makes niobium the material of choice for thin film resonator structures in transmon qubits, one of the leading candidates in quantum computing. While the superconducting properties of the Nb thin film itself are robust, the qubit coherency times are thought to be limited by dielectric losses originating from defects at surfaces and interfaces. We apply atom-probe tomography (APT) to compositionally and structurally characterize the surfaces, interfaces, and grain boundaries in Nb thin-films fabricated by high-power impulse magnetron sputtering (HIPIMS) on silicon substrate. The results indicate the formation of a 5-8 nm thick surface oxide film with a NbO or Nb2O5 stoichiometry on top of the Nb thin film, and the formation of a 6-8 nm thick silicide interreaction layer between the Nb thin-film and the Si substrate. The single-atom time-of-flight mass spectrometric sensitivity of APT is particularly suitable to track presence, location, and concentrations of interstitial impurity elements, H, C, N, and O.

*This work is supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Superconducting Quantum Materials and Systems Center (SQMS) under contract No. DE-AC02-07CH11359.

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Presenters

  • Dieter Isheim

    • Northwestern University

Authors

  • Dieter Isheim

    • Northwestern University

  • Dominic P Goronzy

    • Northwestern University
    • Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States

  • Carlos G Torres Castanedo

    • Northwestern University
    • Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States

  • Michael J Bedzyk

    • Northwestern University
    • Department of Physics and Astronomy, Department of Materials Science and Engineering, Northwestern University

  • Mark C Hersam

    • Northwestern University
    • Materials Science and Engineering, Northwestern University, Evanston, IL 60208

  • James A Sauls

    • Northwestern University

  • Jayss Marshall

    • Rigetti Computing
    • Rigetti Quantum Computing

  • Cameron Kopas

    • Rigetti Computing

  • Mark Field

    • Rigetti Computing

  • Gregory Stiehl

    • Rigetti Computing

  • Hilal Cansizoglu

    • Rigetti Computing

  • Josh Mutus

    • Rigetti Computing

  • Matthew J Reagor

    • Rigetti Computing
    • Rigetti Quantum Computing

  • Michael Harburn

    • Rigetti Computing

  • Alexander Romanenko

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab

  • Anna Grassellino

    • Fermilab
    • Superconducting Quantum Materials and Systems Center (SQMS), Fermilab

  • David N Seidman

    • Northwestern University