Microstructure control in Pb3Bi thin films for Josephson junctions

Investigation of PbBi thin films deposited by thermal evaporation was made in the range of 22–40% of bismuth. Low temperature resistivity and critical superconductive temperature depend strongly on bismuth concentration.SIMS depth profiling, X-ray diffraction and TEM analysis allow us to identify the mixture of crystallized HCPPb₃Bi phase and other surface and internal phases. Drastic oxidation effects were observed on these layers; some additional thin film materials, such as indium and SiO were deposited upon PbBi to reduce oxidation.Low leakage current, niobium-oxide-Pb₃Bi junctions were made with these alloys as counter-electrodes.