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DS: Dünne Schichten

DS 13: Strukturbildung

DS 13.5: Vortrag

Mittwoch, 26. März 2003, 17:45–18:00, GER/37

Growth of CeO2 thin films deposited on biaxially textured nickel substrates — •Dominique Eyidi, Balaji Birajdar , and Oliver Eibl — Institut fuer Angewandte Physik - Universitaet Tuebingen - Auf der Morgenstelle 10 - D-72076 Tuebingen Germany

CeO2 films are used as buffer layers for the integration of superconducting YBa2Cu3O7 films on 100 - biaxially textured Ni substrates. Such coated conductors show critical currents of about 10 000 Amperes pro square centimeters at 0 T and 77 K. The investigated CeO2 films were deposited by a reactive thermal evaporation process with a thickness of 100 nm after deposition. They were characterized by plan view and cross-section transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). They had a strong 100 - biaxial texture with a roughness of approximately 90 nm. No intermediate layer could be found at the Ni-CeO2 interface. The films had columnar grains with diameters of 20 - 50 nm, much smaller than the grain size of the Ni substrate which was larger than 1 micrometer. Small-angle grain boundaries and small amounts of 111- oriented grains are evidenced in plan-view samples. The Moire fringes technique was applied to image the small rotations (less than 3 degrees) of the small CeO2 grains with respect to the Ni substrate. The growth is non-epitaxial, however biaxially textured. In the CeO2 film samples, nanovoids 5 - 10 nm in size were mostly located close to the film surface. A model for the growth of CeO2 thin films on nickel substrates can be proposed on the basis of our results.