APPLICATION OF SILICON SUBSTRATES FOR HIGH-T-C JOSEPHSON-JUNCTIONS AND SQUIDS

We investigated the realization of YBCO Josephson junctions and SQUIDs on 10x10 mm(2) silicon bicrystal substrates and on 2 inch single crys talline silicon wafers. All buffer layers, YBCO films, passivation and metallization layers were deposited with the laser ablation technique . Bicrystal junctions with RSJ-like I-V characteristics, ICRN products of 150 mu V at 77 K and microwave response up to the THz range were r ealized. DC-SQUIDs consisting of these junctions have working temperat ures up to 80 K and transfer functions up to 30 mu V/Phi(o) at 77 K. F urther we enlarge our standard preparation technique of Josephson step -edge junctions on 5x10 mm(2) to 2 inch silicon wafers. YBCO films of this size have a critical temperature T-C > 87 K and critical current densities j(c) (77 K) > 3.10(6) A/cm(2) over the whole wafer area.