Unusual I/V characteristics of Nb/Al/AlOx/Al/AlOx/Nb SINIS tunnel junctions

I. P. Nevirkovets*, J. B. Ketterson, J. M. Rowell

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Double-barrier Nb/Al-AlOx-Al-AlOx-(Al/)Nb devices with various thickness and purity of the middle Al layer were fabricated and investigated. It is found that the subgap structure that appears in the current voltage characteristics is very sensitive to the parameters of the middle film. In addition to the formerly reported gap-difference structure, we observed its half-voltage 'subharmonic' and a novel magnetic-field-sensitive structure that develops at a voltage V≈ΔNb/e (ΔNb is the superconducting energy gap of Nb). In general, the devices with a cleaner Al electrode reveal better reproducibility of their characteristics, whereas the devices with 'impure' Al (deposited in presence of a small amount of oxygen added to the Ar) tend to have more complicated and difficult to reproduce subgap structure. In addition, an anomalously large Josephson critical current was observed for devices with a small thickness of the middle Al layer.

Original languageEnglish (US)
Pages (from-to)212-219
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2000
EventSuperconducting and Related Oxides:Physics and Nanoengineering IV - Orlando, FL, USA
Duration: Apr 24 2000Apr 28 2000

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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