Layer-by-layer preparation of Bi-Sr-Ca-Cu-O films by multitarget sputtering

Abstract

Thin‐film preparation of Bi‐Sr‐Ca‐Cu‐O system has been studied by layer‐by‐layer method using multitarget sputtering. Targets of Bi metal, SrCu and CaCu aloys were used and reactive dc sputtering was carried out in argon and oxygen mixed atmosphere. Oxide thin layers were sequentially deposited in the order of Bi, SrCu, CaCu and SrCu onto MgO(100) substrates heated at 600–700 °C. By adjusting the thickness of each layer to the ideal value, Bi‐based thin films of various crystal structure with different numbers of CuO2 planes between Bi‐O bilayers were selectively prepared. As‐grown films with three CuO2 planes showed the highest superconducting onset temperature (Tc) of 110 K and the highest zero‐resistance temperature of 45 K. Films with two and four CuO2 planes showed Tc’s of 95 K and 85 K, respectively. Films with five CuO2 planes showed high resistivity and exhibited semiconductor‐like behavior. Furthermore, by using this method new Bi‐based multilayer films with different numbers of CuO2 planes were successfully prepared.