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.

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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