PLANAR-TYPE BA1-XKXBIO3 JOSEPHSON TUNNEL-JUNCTIONS PREPARED ON SRTIO3BICRYSTAL SUBSTRATES

We have prepared planar-type Josephson junctions using Ba1-xKxBiO3 thi n films deposited on SrTiO3 bicrystal substrates by the rf magnetron s puttering method, and investigated their properties. The current-volta ge characteristics of the junctions were those of superconductor-insul ator-superconductor junctions and both the Josephson current and the e nergy gap were observed clearly. The critical current density of the j unction was 5.5X10(2) A/cm2 at 4.2 K and the I(c)R(n) product was 2.2 mV. A magnetic field applied perpendicular to the substrate modulated the critical current, which gave a clear Fraunhofer pattern.