Effects in sputtered Y1Ba2Cu3O7-8 films

The fabrication of superconducting Y1Ba2Cu3O7-delta films by d.c. sputter deposition was investigated. The observed compositional deviations of the films from the target composition can be explained by a selective resputtering effect from the films as a result of oxygen anions emitted from the target. This can be concluded from a study of the thickness profile, the morphology, and the compositional inhomogeneity of the films. Also, a strong substrate temperature dependance of the film composition, i.e. an increase of the barium deficiency in the films at higher substrate temperatures, is observed. By using a magnetron cathode, the film composition can be improved and films of 1:2:3 composition can be prepared reproducibly. Moreover, successful preparation of sputtered Bi0.8Pb0.2Ca1Sr1Cu2chi films with Tc,zero=70K is reported.