Morphology and superconducting properties of photo-assisted MOCVD processed YBCO film by variation of sublimation temperature of the Cu-based precursor

Abstract: Normally, surface of c-axis oriented YBCO films grown by MOCVD are found to be populated by micron-sized outgrowths with elemental compositions such as Ba–Cu–O and Cu–O. For both low and high current applications with the YBCO films, these surface outgrowths should be eliminated. In this study, it is found that by using a simple processing technique of decreasing appropriately the sublimation temperature of the Cu-based precursor, the surface outgrowths can be essentially subdued. At the same time it is qualitatively predictable that J c of these smoother YBCO films will be lowered. However, experimentally, it is found that at appropriate YBCO film growth conditions, the lowered J c value is acceptable for most applications. Actually, a surface outgrowth covered YBCO film made by photo-assisted MOCVD, with film composition Y:Ba:Cu as 1:1.2:1.5, has its J c being 3.4MA/cm2 (0T, 77K). As composition of YBCO film is changed to 1:0.9:1.2 by lowering the sublimation rate of the Cu-based precursor, then there are no more outgrowths on surface, with its J c being 2.6MA/cm2. [Copyright &y& Elsevier]