Concentration Effect of Pb in Sputter-Deposited Bi-Sr-Ca-Cu-O Superconducting Thin Films

Superconducting thin films of the Pb-doped Bi-Sr-Ca-Cu-O system have been prepared on MgO substrates by dc magnetron sputtering using a single sintered target. After deposition at 400°C and post-annealing at 850°C for 3 h in air, we have succeeded in obtaining highly c-axis oriented thin films which have shown zero resistivity at 115 K. In order to examine the effect of Pb concentration, composition analysis was performed by electron probe X-ray microanalysis. As a result, the composition of the as-sputtered films deposited below 400°C was almost the same as that of the targets, except for a slight decrease in the Bi concentration. Further, we found that the Pb-content of the film decreased quickly only during the early stage of annealing at 850°C and quite slowly thereafter.