Preparation of Bi-Sr-Ca-Cu-O thin film by coevaporation and its thermal stability

Abstract

Thin film with a high T_c single phase was prepared on a (100)MgO substrate at a substrate temperature of about 620 °C by coevaporation of Bi₂O₃, Sr, Ca, and Cu metal. The resistive superconducting transition with onset T_c of 80 K was observed for this film. By post‐deposition annealing at 850 °C, the high T_c phase was transformed into a low T_c phase, while films annealed at a higher temperature such as 890 °C maintained the high T_c phase. These results indicated that the high T_c phase can exist only at the high‐temperature region (∼890 °C) while the stable phase existing at the low‐temperature region (∼850 °C) is the low T_c phase.