Superconducting Y-Ba-Cu-O thin films on Si and Al 2 O 3 substrates

YBaCuO superconducting thin films have been prepared by sequential evaporation of Cu, Y 2 O 3 and BaF 2 layers on Si[100] and polycrystalline Al 2 O 3 substrates. One, ten and thirty-sequences were evaporated on Si[100] with a 0.6 μm ZrO 2 buffer layer. The effects of different buffer layers were studied for Al 2 O 3 substrates by means of the deposition of ZrO 2 , Cu, Ag and BaTiO 3 layers with thicknesses of 20, 100 and 500 nm. The film properties were studied using electrical measurements, scanning electron microscopy, x-ray diffractometry, electron microprobe analysis and secondary ion mass spectrometry. The best properties were found in the film obtained on ZrO 2 /Si[100] with one-sequence. The studies of the different buffers show a strongly dependence of the film properties on the nature and thickness of the buffer, with the best results for films deposited on an Ag layer.