INTERFACIAL INTERACTIONS OF YBA2CU3O7-X THIN-FILMS ON SI SUBSTRATES WITH POLYCRYSTALLINE Y STABILIZED ZRO2 BUFFER LAYERS

The interfacial interactions of high-temperature superconducting YBa2C u3O7-x (YBCO) thin films on Si substrates with polycrystalline yttrium -stabilized ZrO2 (YSZ) buffer layers have been characterized using tra nsmission electron microscopy in combination with X-ray microanalysis. It has been found that polycrystalline YSZ buffer layers do not preve nt detrimental interdiffusion between a Si substrate and a YBCO film d uring film deposition at 700 to 750 degrees C. Diffusion is relatively fast along the grain boundaries of the columnar-structured YSZ buffer layer and results in the formation of Cu rich precipitates at the YSZ /Si interface and in amorphous regions at the YBCO/BaZrO3/YSZ interfac e. In addition, a local surface roughness of the YSZ upper interface g ives rise to significant deviation from the c-axis orientation of the YBCO film ([001] axis of YBCO parallel to the surface normal of the Si substrate). It is therefore important to maintain a smooth surface as well as an epitaxial growth of the YSZ buffer layer.