Interaction of YBCO thin film and substrates and its effects on the quality of the film

YBCO thin films grown on SrTiO3, yttria-stabilized zirconia (YSZ), and YSZ with a CeO2 buffer layer, by pulsed laser deposition, were studied by high resolution X-ray diffraction, including rocking curves, and Phi-scans. It i s shown that the distortion of the thin films is different in the different substrates. The lattice mismatch between them can partially explain this. The larger mismatch corresponds to the larger distortion of the films, whic h can be determined by the full width at half maximum (FWHM) in the rocking curve and Phi-scan curve. As the mismatch between the film and substrate i ncreases, the FWHM of both rocking curve and Phi-scan curve increases simul taneously. But, the YBCO on the YSZ with CeO2 buffer layer does not obey th is regulation. The careful calculation of the cohesive energy of the thin f ilms and substrates, especially considering the effect of the interaction o f the YBCO and substrates, indicates there is a close relationship between the cohesive energy and the distortion of the films. Using this to explain the distortion is better than using mismatch. (C) 2000 Elsevier Science B.V . All rights reserved.