SRTIO3 BUFFER LAYERS AND TUNNEL BARRIERS FOR BA-K-BI-O JUNCTIONS

Epitaxial SrTiO3 films were used as buffer layers and tunnel barriers for Ba0.6K0.4BiO3 (BKBO) films and tunnel junctions, respectively. In contrast to BKBO films grown directly on LaAlO3, films grown on SrTiO3 (001) buffer layers on LaAlO3 had a single (001) growth orientation, with T(c)'s of 26 K and DELTAomega = 0.7-degrees. These values are bot h equal to those obtained for growth on a SrTiO3 Single crystal. A sim ilar improvement was obtained for BKBO grown on SrTiO3-buffered NdGaO3 substrates. Tunnel junctions consisting of BKBO(001)/SrTiO3/BKBO laye rs had substantial contributions to the gap voltage from both the base and top BKBO electrodes.