Compositional Dependence of Properties of rf-Sputtered Bi-Sr-Ca-Cu-O thin Films

Authors: Ayhan GÜLDESTE

Abstract: Compositional dependence of superconducting transition temperature (T_c) of Bi_2Sr_{3-x}Ca_xCu_2O_{8+x} thin films grown by rf sputtering on single crystal MgO substrates has been investigated. Films have been assessed by considering their initial composition in terms of (Ca+Sr)/Bi ratio with their atomic concentration normalized to Cu:2. It was found that T_{c-zero} of around 80K is achievable for (Ca+Sr)/Bi ratio between 1.4 and 1.65, while T_{c-onset} remains above 90K. Quenching from high temperature increased T_{c-zero,} but it may result in a deterioration in resistivity due to micro cracks induced by the thermal stress.

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