Formation of As-Grown BiSrCaCuO Thin Films by Sputtering Three Targets Heavily Doped with Pb in Atmospheres of O2 and N2O/O2 Mixtures

Abstract

As-grown BiSrCaCuO thin films have been formed on MgO(100) substrates at various temperatures by RF magnetron sputtering from three targets in atmospheres of neat O₂ and N₂O/O₂ mixtures (1:1). The three targets had slightly different compositions heavily doped with Pb: Bi₃Pb₃Sr₂Ca₂Cu₃O _x , Bi₂Pb₂Sr₃Ca₃Cu₃O _x and Bi₂Pb₂Sr₂Ca₂Cu_4.5O _x . Both films formed in O₂ and N₂O/O₂ mixtures at 660°C showed zero resistivity at 77–78 K. A film obtained at 540°C by N₂O/O₂ mixtures showed superconductivity, while a film obtained at the same substrate temperature by neat O₂ did not. Gas mixtures of N₂O and O₂ used instead of neat O₂ as a sputtering gas were effective in lowering the growth temperature by 20–40 degrees.