Improvement of Surface Flatness on BiSrCaCuO Film

This paper reports on the improvement of the surface flatness on BiSrCaCuO films. By keeping the film surface in contact with a MgO(100) plane during annealing, it is possible to greatly improve the surface flatness at each annealing temperature. The smooth surface is mainly made up of several-µm platelike crystals approximately 60 nm thick. The average surface roughness is determined by the annealing temperature, regardless of film thickness, in the range of 0.1–1.5 µm. As the critical temperature and surface morphology change due to the contacted MgO crystal plane, the improvement of surface flatness is considered to result from the crystal growth restriction on the film surface in contact with a MgO(100) plane.