Transport and structural properties of Bi-Sr-Ca-Cu-oxide thin films prepared by reactive magnetron sputtering

Highly oriented superconducting thin films of Bi-Sr-Ca-Cu-oxides have been reproducibly prepared by reactive magnetically-enhanced triode sputtering using three separate metal targets (Sr, Ca, and Cu-Bi). The as-deposited films had composition ratios of Bi:Sr:Ca:Cu that were very close to either 2:2:1:2 or 2:2:2:3. The films were deposited on SrTiO ₃, MgO, CaF₂, Al₂O₃, and yttria stabilized zirconia (YSZ) substrates and had thicknesses of about 250 nm. After deposition, the films were annealed to 850-900°C in various partial pressures of oxygen (0.05, 0.2 and 1 atm). Films deposited on [100]SrTiO₃ and [100]MgO substrates showed little or not interaction with the substrate after annealing and are the primary focus of this study. Significant substrate interaction and poor film quality were observed for films on CaF₂, Al₂O ₃, and YSZ substrates. Reduced partial pressures of oxygen (0.05 and 0.2 atm.) generally gave the highest quality films for a given annealing cycle. The electrical resistance of the best 2212 films on MgO and SrTiO₃ decreased approximately linearly with temperature until the onset of superconductivity at about 85 K