Scanning tunneling microscopy and spectroscopy characterization of Nb films for quantum applications

G. Berti, C. G. Torres-Castanedo, D. P. Goronzy, M. J. Bedzyk, M. C. Hersam, C. Kopas, J. Marshall, M. Iavarone*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Niobium thin films are key components of superconducting microwave resonators. Interest in these devices has increased dramatically because of their application in quantum systems. Despite tremendous effort to improve their performance, loss mechanisms are still not well understood. Nb/substrate and Nb/air interfaces are likely culprits in contributing to decoherence and ultimately limiting the performance of superconducting devices. Here, we investigate the Nb/substrate interface by studying the effect of hydrogen-passivated H:Si(111) substrates on the local superconducting properties of ∼40 nm thick Nb films compared to Nb films grown on typical Si(001) substrates. Specifically, low-temperature scanning tunneling microscopy and spectroscopy are employed to compare nanoscale material properties. The atomically flat monohydride H:Si(111) substrates are found to yield a smoother and less defective interface with the Nb film. Correspondingly, the Nb films grown on H:Si(111) substrates present more uniform superconducting properties and exhibit less quasiparticle broadening.

Original languageEnglish (US)
Article number192605
JournalApplied Physics Letters
Volume122
Issue number19
DOIs
StatePublished - May 9 2023

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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