Preparation and properties of superconducting Bi–Sr–Ca–Cu–O thin films on polycristalline silver substrates by organometallic chemical vapor deposition

Abstract

Abstract High- T c superconducting Bi–Sr–Ca–Cu–O thin films have been successfully prepared by low-pressure organometallic chemical vapor deposition using metallic silver as a substrate. N 2 O is employed as an efficient reactant gas in combination with the volatile metal-organic complexes Cu(acetylacetonate) 2 , Sr(dipivaloymethanate) 2 , Ca(dipivaloymethanate) 2 , and triphenyl bismuth (Bi(C 6 H 5 ) 3 ) as sources. X-ray diffraction measurements reveal that the as-deposited films deposited at 625–650°C contain a mixture of the Bi 2 (Sr,Ca) 2 CuO x and Bi 2 (Sr,Ca) 3 Cu 2 O x phases, and that the proportion of the high- T c phase increases with increasing deposition temperature. The post-annealed films are composed predominantly of the Bi 2 (Sr,Ca) 3 Cu 2 O x phase with high preferential orientation of the crystallite c axes perpendicular to the substrate surface. Deposition on polycrystalline Ag substrates significantly improves the texture and morphology of BSCCO films as compared with films deposited on MgO. Possible mechanisms for the improvement of BSCCO films when using Ag as a substrate are discussed.