High temperature Josephson bicrystal junctions and arrays for metrological applications

Concerning metrological applications of high-temperature superconductor (HTS) Josephson junctions, we investigated the properties of gold shunted bicrystal YBCO junctions on yttria-stabilized zirconia (YSZ) and sapphire substrates. We focus on three important items that are related to the problem of parameter spreads: (a) the control of the shunt resistance-this parameter is dominated by the contact resistivity between the YBCO and the Au-a direct method for the measurement of this crucial parameter was applied; (b) the impact of the shunt resistance and the spread in junction resistance on the tolerable junction size and the frequency working regime for metrological arrays; and (c) the realization of series arrays with a high packing density of junctions using electron-beam-patterning. The parameter spreads are comparable to those of standard lithography processed junctions.