Resistance of Nb-Pb-alloy Josephson tunnel junctions at cryogenic and ambient temperatures

Abstract

We report experimental measurements of the ratio of the tunneling resistance of edge junctions at ∼4 and ∼300 K. The results, after correction for the contribution of the electrode resistance in the normal state, are compared with theory. The temperature dependence measured in these Nb-NbOx-Pb-alloy junctions is greater than the theory for a simple trapezoidal ∼0.5 eV high barrier. Nevertheless, the consistency of the ∼4 and ∼300 K tunneling resistances is adequate to allow the use of the resistance at ambient temperature as a process monitor in Josephson junction circuit fabrication.