SUPERSTRUCTURE IN THIN-FILMS OF BI-BASED COMPOUNDS ON MGO

In situ epitaxial growth of BiSrCaCuO films by three target sputtering was performed on MgO substrates at a temperature of 650°C. From high resolution transmission electron microscopy, the film showed a superstructure consisting of the alternate stacking of the low-Tc and high-Tc phases with a c-axis of 34 Å. The film in the [110] or [110] directions was parallel to<100>MgO, and the transient layers between the substrate and the film were less than a few atomic layers thick. X-ray diffraction simulations indicated that the films contained random layer ordering of 34 Å bi-layers (low-Tc+high-Tc and high-Tc+low-Tc) and random layer ordering of low-Tc and high-Tc phase layers. © 1990 The Japan Society of Applied Physics.