Effect of in situ and ex situ annealing on the growth of Bi2Sr2Can-1CunOy sputtered films

We prepared Bi2Sr2CaCu2Oy (Bi-2212) films by the rf magnetron sputtering method with a single target using an off-axis geometry and a gas mixture of He and O2, and investigated the effect of in situ and ex situ annealing on the crystallinity and superconductivity of the as-deposited Bi-2212 film without any other phases. We found that in situ annealing improved the crystallinity of the as-deposited films, and that ex situ annealing improved both the crystallinity and superconductivity of the as-deposited films. The optimum temperatures of in situ and ex situ annealing were 630 and 800 deg. C, respectively. (author)