Investigation of in-situ Ag/YBCO contacts for SNS devices

Using a completely in-situ process, the authors have investigated Ag metal contacts to thin films of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7/, in order to study the properties of the Ag/YBCO interface as well as the Josephson effect in SNS (superconductor-normal-superconductor) bridges made with this technique. Measurements of the temperature dependence of the Josephson current in these devices have been made and are compared to recent theoretical predictions. SNS devices which exhibited Josephson effects had the critical-current-resistance products of the junctions limited by the high specific contact resistance of the SN interfaces. The lowest values of the specific contact resistance obtained were on the order of 10/sup -8/ Omega -cm/sup 2/ for contacts in the c-axis direction. The influence of the specific contact resistance on the magnitude of the Josephson current in SNS bridges is discussed.<
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