Fabrication of full high-Tc superconducting YBa2Cu3O7-x trilayer junctions using a polishing technique

We have successfully fabricated full high-T-c superconducting YBa2Cu3O7-x(YBCO)/PrBa2Cu3O7-x(PBCO)/YBCO trilayer junctions, which have a simple device structure, such as a Pb-alloy-based Josephson tunneling junction. It has been demonstrated that a polishing technique is extremely useful in the fabrication process: it is effective in smoothing a coarse surface and gentling the slopes of the edges, or decreasing the slope angles. Owing to the polishing technique, the PBCO barrier layer and the upper YBCO layer have been notably thinned: the thicknesses of these. layers are 10 nm and 250 run, respectively. Junctions with the dimensions of 5 mum x 5 mum showed resistively shunted junction-like current-voltage curves with a typical critical current density of 110A/cm(2) at 4.2K. Furthermore, the operation of superconducting quantum interference devices has been demonstrated.