Effect of oxygen partial pressure on the surface morphology of sputtered YBCO thin films

Abstract

YBCO thin films were fabricated by off-axis rf magnetron sputtering at various oxygen partial pressures to obtain a smooth surface morphology applicable to the fabrication of various heterostructures, such as a perovskite-type ferroelectric film on YBCO, a Pr(1-x)ca(x)MnO(3) film on YBCO for a high-density nonvolatile memory, and so on. The surface morphologies of the YBCO thin films were enhanced gradually with increasing oxygen partial pressure; finally, a smooth surface was obtained at the highest oxygen partial pressure attempted in this study, at which the flow rates of 02 and Ar were 5 and 1 sccm, respectively (02 : Ar = 5 : 1). Both the stoichiometric composition and the growth rate compatible with the substrate temperature were found to be favorable for getting a smooth surface morphology for YBCO thin films.