STUDY OF Y1BA2CU3O7-DELTA FILM GROWTH ON (200) ORIENTED YTTRIA-STABILIZED ZIRCONIA BUFFER LAYER ON METALLIC SUBSTRATES

This work presents the first report on the growth mechanism of 123 fil ms on metallic substrates with (200) oriented and partially a-b plane oriented polycrystalline yttria stabilized zirconia (YSZ) buffer layer , with and without a metallic underlayer coating used between the subs trate and the buffer layer. The microstructure and grain morphology of 9- and 160-nm-thick films of Y1Ba2Cu3O7-delta (YBCO) were studied by scanning electron microscopy, scanning tunneling microscopy, and x-ray diffraction. Our studies reveal that YBCO films on c-axis oriented an d partial a-b plane oriented YSZ buffer layers on metallic substrates, initially grow two dimensionally, with the elongated grains of approx imately 100 nm length, mostly aligned along the (200) axis of the YSZ, owing to the strong atom-substrate bonding. The thicker films, howeve r, show three-dimensional terraced island growth with several turns of the screws, with the screw edges still along the (200) axis of YSZ. T hese terraced islands seem to coalesce in the film with the highest J( c) value, approximately 1 X 10(5) A/cm2.