Development of low contact resistivity electrode for HTSC films

The electrodes on LPE films for the case of persistent current switches were developed. The electrode was fabricated by the sputtering method using targets of Ag-based metal alloys. In the targets, the different amounts of Cu were added in order to suppress the reaction between the RE123 and the electrode metal films. Consequently, the suitable composition of the Ag–Cu electrode to obtain a low contact resistance was found. When the copper composition in the Ag electrode was controlled to be 1.09 wt.%, the lowest contact resistance of 1.7×10−12 Ωm2 was obtained. And all of these results are reasonable values as the requirements for the LPE film. Moreover, we found that a thick film is necessary to fabricate electrodes with low contact resistivity since fine grains in a small bare surface area were expended due to vaporization, etc., by the heat treatment in the case of thin films.