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

I. P. Nevirkovets; J. B. Ketterson; J. M. Rowell

doi:10.1117/12.397836

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

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

^*Corresponding author for this work

Physics and Astronomy

Research output: Contribution to journal › Conference article › peer-review

1 Scopus citations

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≈Δ_Nb/e (Δ_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.

Original language	English (US)
Pages (from-to)	212-219
Number of pages	8
Journal	Proceedings of SPIE - The International Society for Optical Engineering
Volume	4058
DOIs	https://doi.org/10.1117/12.397836
State	Published - 2000
Event	Superconducting and Related Oxides:Physics and Nanoengineering IV - Orlando, FL, USA Duration: Apr 24 2000 → Apr 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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title = "Unusual I/V characteristics of Nb/Al/AlOx/Al/AlOx/Nb SINIS tunnel junctions",

abstract = "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.",

author = "Nevirkovets, {I. P.} and Ketterson, {J. B.} and Rowell, {J. M.}",

year = "2000",

doi = "10.1117/12.397836",

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note = "Superconducting and Related Oxides:Physics and Nanoengineering IV ; Conference date: 24-04-2000 Through 28-04-2000",

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T1 - Unusual I/V characteristics of Nb/Al/AlOx/Al/AlOx/Nb SINIS tunnel junctions

AU - Nevirkovets, I. P.

AU - Ketterson, J. B.

AU - Rowell, J. M.

PY - 2000

Y1 - 2000

N2 - 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.

AB - 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.

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Y2 - 24 April 2000 through 28 April 2000

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

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