Highly oriented Bi(Pb)-Sr-Ca-Cu-O superconducting thin films by magnetron sputtering of a single target

Abstract

Superconducting Bi(Pb)-Sr-Ca-Cu-O thin films have been prepared onto (100) MgO substrates by dc magnetron sputtering using a single sintered target. The targets used were Bi2.7 ,Pbx Sr2 Ca2.25 Cu3.75 Oy (x=1.5, 1.75, 2.0, 2.25 and 2.5) in nominal composition. All the films were deposited at 400 °C and annealed at 850 °C for 3 h in air. Although the superconducting properties of the thin films were very sensitive to the Pb content of the target, reproducible results were obtained. After deposition from the target with x=2.0 and subsequent high-temperature annealing, we have succeeded in obtaining highly c-axis oriented thin films which have shown zero resistivity at 115 K. This may be due to the optimum substitution of Pb for Bi in addition to the conditions during the high-temperature process. The average cationic ratio of the film was shown to be Bi:Pb:Sr:Ca:Cu=1.75:0.17:2:2.1:3.2 by electron-probe x-ray microanalysis.