RF plasma deposition and in-situ property enhancement of Bi₂Sr₂Ca_n-1Cu_nO_x thin films

An atmospheric pressure, inductively coupled, argon-oxygen RF plasma process has been used to prepare, in-situ, superconducting Bi₂Sr₂Ca_n-1Cu_nO_x thin films. Film properties have been enhanced by exposing the grown film, in-situ, to the same argon-oxygen plasma used for its deposition. This is achieved by switching off the atomized precursor nitrate solution to the plasma torch. T_c's of 76 K and J_c's of 1.3 × 10⁵ A/cm² at 60 K and zero field have been achieved in the in-situ, Bi₂Sr₂Ca₁Cu₂O_x films. Bi₂Sr₂Ca₂Cu₃O_x films with T_c's of 100 K and J_c's of 1 × 10⁵ A/cm² at 77 K and zero field have also been grown. The effects of film exposure to the plasma for different time periods and RF power levels are discussed. The effects of deposition parameters, such as substrate temperature, bismuth content, solution concentration and phase control, are analyzed. Finally, the critical current behavior of the films under a external magnetic field of up to 5 T is reported.