Very Large Scale Integration of Nano-patterned YBa$_2$Cu$_3$O$_{7-\delta}$ Josephson Junctions in a Two-dimensional Array

ORAL

Abstract

Very large scale integration of Josephson junctions in a two- dimensional series-parallel array has been achieved by ion irradiating a YBa$_2$Cu$_3$O$_{7-\delta}$ film through slits in a nano-fabricated mask created with electron beam lithography and reactive ion etching. The mask consisted of 15,820 high-aspect ratio (20:1), 35-nm wide slits that restricted the irradiation in the film below to form a 28 x 565 Josephson junction array. Characterizing each parallel segment, containing 28 junctions, with a single critical current we found a standard deviation of about 16\%. To study array configuration, the number of SQUIDs connected in parallel was decreased by etching the array with photolithography and ion milling. We compare voltage --- magnetic field characteristics for the different configurations and have found that the modulation depth of the voltage has a much stronger than expected dependence on the inductances of the SQUIDs.

*This work supported by AFOSR FA9550-08-1-0305.

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Authors

  • Shane Cybart

    • Materials Sciences Division, Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley, CA 94720

  • S.M. Anton

    • University of California, Berkeley
    • Department of Physics, University of California, Berkeley, CA 94720

  • S.M. Wu

    • Department of Physics, University of California, Berkeley, CA 94720

  • John Clarke

    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California, Berkeley
    • UC Berkeley
    • Dept. of Physics, UC Berkeley
    • Department of Physics, University of California Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley, CA 94720

  • R.C. Dynes

    • Materials Sciences Division, Lawrence Berkeley National Laboratory
    • Department of Physics, University of California, Berkeley, CA 94720