Synthesis and characterisation of nanostructured barium cuprate thin films

Thin films of Ba_1-yCuO_2+x system were prepared by DC magnetron sputtering technique, using a BaCuO2 target sintered at 850°C for 24 hours. The sputtering was performed under 0.04 Torr Ar-pressure and at 500 V- 135 mA target current. The effect of substrate and substrate bias on the morphology of the films was investigated. The films were characterised by atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD and XPS analyses revealed a major phase closed to BaCuO₂ as well as a minor phase of BaCO₃ (30%). AFM observations in the phase mode showed a uniform distribution of isolated grains covering about 30% of the film. We identified these grains with BaCO ₃. The AFM images in the topography mode showed a uniform distribution of 60 nm diameter grains of BaCuO₂.