In-situ preparation of superconducting Bi-Sr-Ca-Cu-O thin films by high pressure DC sputtering

Superconducting Bi-Sr-Ca-Cu-O films on (100) MgO substrates have been reproducibly prepared by the high-pressure DC sputtering process without further annealing treatment. The sputtering gas was Ar-50%O₂, and total gas pressure was 1.5 torr. The target was Bi₂Sr₂Ca_1.3Cu₂O_x composite made by solid-state reaction. The substrate temperatures were 600-750°C. The film thickness is 0.8-1.5 μm. The films consisted of highly c-oriented Bi₂Sr₂Ca₁Cu₂ O_x or Bi₂Sr₂Cu₁O_x phase. The best superconducting properties of the films are T_c(onset)=93 K and T_c (R=0)=68 K. The detailed process and effect of processing parameters on superconductivities, phases, and surface morphologies of the films are discussed