DC sputtered high-temperature superconducting thin films in the Bi-Sr-Ca-Cu-O system

Abstract
High-Tc superconducting thin films have been successfully obtained from single-target DC sputtering deposition followed by an appropriate annealing. Sapphire and (100) SrTiO3 substrates were used. In the latter case, strongly oriented c-axis films were obtained. For the nominal composition 2:2:1:2 the films exhibit a strong metallic behaviour in the normal state and a sharp superconducting transition, with an onset around 84 K. The critical current density is at least 2*103 A cm-2 at 70 K. For the composition 1:1:1:2 a kink in the R(T) curve clearly appears near 110 K. This transition appears especially sensitive to thermal treatment.