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

Ivan P. Nevirkovets; John B. Ketterson; J. M. Rowell

doi:10.1117/12.397836

6 September 2000 Unusual I/V characteristics of Nb/Al/AlO_x/Al/AlO_x/Nb SINIS tunnel junctions

Ivan P. Nevirkovets, John B. Ketterson, J. M. Rowell

Proceedings Volume 4058, Superconducting and Related Oxides: Physics and Nanoengineering IV; (2000) https://doi.org/10.1117/12.397836
Event: AeroSense 2000, 2000, Orlando, FL, United States

Abstract

Double-barrier Nb/Al-AlO_x-Al-AlO_x-(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 approximately equals (Delta) _Nb/e ((Delta) _Nb 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.

Citation Download Citation

Ivan P. Nevirkovets, John B. Ketterson, and J. M. Rowell "Unusual I/V characteristics of Nb/Al/AlO_x/Al/AlO_x/Nb SINIS tunnel junctions", Proc. SPIE 4058, Superconducting and Related Oxides: Physics and Nanoengineering IV, (6 September 2000); https://doi.org/10.1117/12.397836

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