Vacuum deposition of multilayer Bi-Ca-Sr-Cu-O superconducting thin films

Superconducting Bi-Ca-Sr-Cu-O thin films were prepared by sequential evaporation of layers of Cu, Ca, Bi2O3, and Sr on single-crystal MgO substrates, followed by an anneal in an O2 atmosphere. An electron beam source was used for Sr and resistively heated sources for Cu, Ca, and Bi2O3. An onset transition temperature of around 80 K was observed with a resistance anomaly at 105 K. The film properties were found to be very sensitive to the anneal conditions. Samples were characterized by resistivity measurements, Auger spectroscopy, scanning electron microscopy, and energy dispersive x-ray microanalysis.