Preparation of high-Tc superconducting Bi-Sr-Ca-Cu-O films by organometallic chemical vapor deposition using second-generation fluorocarbon-based precursors

High-Tc superconducting Bi-Sr-Ca-Cu-O thin films with good electrical properties and smooth surface morphologies have been prepared by low-pressure organometallic chemical vapor deposition using the new fluorocarbon-based precursors Sr(hexafluoroacetylacetonate)2⋅tetraglyme and Ca(hexafluoroacetylacetonate)2⋅triglyme together with Cu(acetylacetonate)2 and triphenylbismuth [Bi(C6H5)3]. The fluorinated precursors are air-stable and exhibit high, stable volatility even after prolonged heating. X-ray diffraction measurements reveal that the films deposited at 650 °C contain some fluoride phases but no high-Tc phases. However, post-annealing in oxygen produces films composed predominantly of the Bi2Sr2CaCu2Ox phase with high preferential orientation of the crystallite c axes perpendicular to the substrate surface. Four-probe resistivity measurements indicate the onset of film superconductivity at ∼100 K and zero resistivity achieved at 73 K.