Preparation of superconducting Bi-Sr-Ca-Cu-oxide thin films by thermal evaporation

Abstract
Superconducting Bi-Sr-Ca-Cu-oxide thin films were prepared by sequential evaporation of two layers of Ca/Cu and Bi/Sr on single-crystal SrTiO3 substrates followed by a two-step oxidation process. The film properties were found to be sensitive to the annealing conditions. The best films showed a narrow transition to superconductivity (5 K) and the completion of the transition above 83 K. X-ray analysis of the films showed a strong correlation of the midpoint of the transition with the dimensions of the unit cell.