Growth of Bi-Sr-Ca-Cu-O ribbon-like thin films on sputter-deposited Ag film

This is a report on the melt growth process of Bi2Sr2Ca1Cu2Ox ribbon-like t hin films on sputter-deposited Ag films. Ag films were used as the substrat es for this process instead of Ag plates because their flat surfaces are su perior to the Ag plate surfaces. Six Ag films on MgO single crystal (001) w ere prepared. Their deposition rates ranged from 11.2 to 51.4 Angstrom /s. Although the flatness of the Ag films as they were deposited was similar to 1 nm independent of the deposition rate, the (001) texture of the Ag films that had been deposited slowly was superior. After annealing, the films wit h a faster sputter deposition rate were roughened (> 100 nm). On the other hand, even though the roughness of the Ag films at a slower sputter deposit ion rate increased (< 40 nm), the films retained a mirror-like surface even after annealing. The ribbon-like crystals on these Ag films grew by the me lt process only on the Ag films that lost their flatness (> 100 nm). The ro ughness of the surface allows for further crystal growth during the melting process, which can be attributed to the capillary phenomenon. The results suggest that the wettability is important during the melting process on the Ag surface to the growth of the ribbon-like thin films. (C) 2001 Elsevier Science B,V. All rights reserved.