High quality La1.8Sr0.2CuO4and YBa2Cu3O7superconducting thin films, with zero resistance at 88 K, have been made by dualhyphen;ionhyphen;beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 mgr;m thick and are single phase after annealing. The substrates investigated are Ndhyphen;YAP, MgO, SrF2, Si, CaF2, ZrO2hyphen;9percnt; Y2O3, BaF2, Al2O3, and SrTiO3. Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, transmission electron microscopy, xhyphen;ray diffraction, and secondary ion mass spectroscopy. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa2Cu2O7structure, in the case of SrTiO3substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film. In general, the superconducting transition temperature is found to depend on substrate temperature and ion beam energy, film composition, annealing conditions, and the nature and the magnitude of the substrate/film interaction.
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