Microstructure of superconducting YBa sub 2 Cu sub 3 O sub 7 minus. delta. thin films on Si and alumina substrates with buffer layers

The microstructure of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) films grown on silicon and alumina substrates with yttria-stabilized zirconia (YSZ) buffer layers has been studied by transmission electron microscopy (TEM) and x-ray diffraction. The as-deposited films are not amorphous, but are in fact composed of small crystalline grains. The top surface of the post-annealed YBCO film consists mainly of the orthorhombic structure of YBCO with large grains. Other phases are present within the films and have been identified. The presence of a very thin interdiffused layer of BaZrO{sub 3} between the YSZ and the YBCO has been shown by cross-sectional TEM.