• DocumentCode
    1474477
  • Title

    Fabrication of Nb/Al-Nx/NbTiN junctions for SIS mixer applications

  • Author

    Bumble, B. ; LeDuc, H.G. ; Stern, J.A. ; Megerian, K.G.

  • Author_Institution
    Jet Propulsion Lab., California Inst. of Technol., Pasadena, CA, USA
  • Volume
    11
  • Issue
    1
  • fYear
    2001
  • fDate
    3/1/2001 12:00:00 AM
  • Firstpage
    76
  • Lastpage
    79
  • Abstract
    We discuss fabrication and characteristics of superconductor-insulator-superconductor (SIS) junctions which typically exhibit a 3.5 mV sum-gap voltage. Junctions have a sub-gap to normal state resistance ratio of RSG/RN=27 for resistance-area products down to RNA=8 Ω μm2 and high quality junctions have been produced with RNA products as low as 4 Ω μm2. The device structure incorporates a Nb base electrode, a tunnel barrier formed by plasma nitridation of a thin Al proximity layer, and a NbTiN counter-electrode. Results for all Nb junctions with high current density aluminum-nitride barriers are also shown. Nitridation of the aluminum layer is investigated by control of the dc floating potential on a separate rf driven electrode in the vacuum process chamber. Devices are integrated to a mixer antenna structure incorporating NbTiN as a ground plane. The wire circuit layer can be either normal metal or NbTiN. Annealing results show improved I-V characteristics with increased RNA products. Recent receiver measurements employing these junctions exhibit low noise performance up to 900 GHz
  • Keywords
    aluminium compounds; annealing; niobium; niobium compounds; nitridation; submillimetre wave mixers; superconducting device noise; superconducting microwave devices; superconductor-insulator-superconductor mixers; titanium compounds; type II superconductors; 3.5 mV; I-V characteristics; Nb base electrode; Nb-AlN-NbTiN; Nb/Al-Nx/NbTiN junctions; NbTiN counter-electrode; SIS mixer applications; annealing; dc floating potential; fabrication; low noise performance; mixer antenna structure; nitridation; plasma nitridation; resistance-area products; rf driven electrode; sub-gap/normal state resistance ratio; sum-gap voltage; superconductor-insulator-superconductor junctions; thin Al proximity layer; tunnel barrier; wire circuit layer; Current density; Electrodes; Fabrication; Josephson junctions; Niobium; Plasma density; Plasma devices; RNA; Superconducting devices; Voltage;
  • fLanguage
    English
  • Journal_Title
    Applied Superconductivity, IEEE Transactions on
  • Publisher
    ieee
  • ISSN
    1051-8223
  • Type

    jour

  • DOI
    10.1109/77.919288
  • Filename
    919288
    • Link To Document
    https://search.isc.ac/dl/search/defaultta.aspx?DTC=49&DC=1474477