Reactive coevaporation of YBaCuO superconducting films

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Abstract
Growth conditions for YBaCuO thin films are investigated. Films have been made by reactive e-beam coevaporation using three metal sources. In the best cases, as-made films are superconducting with Tc's (R = 0) up to 90 K and Jc's (at 4.2 K) above 107 A/cm2. Oxygen pressure, deposition temperature, as well as compositional dependencies of the films are presented. It is found that in conditions of lower oxygen, pressure films with average composition off the 1–2–3 stoichiometry have higher Tc's. For pressure 100 mTorr). The expanded c0's for these films cannot be reduced by a low temperature oxygen anneal. We suggest that metal-atom point-like defects are quenched into these films and we discuss a particular Ba-for-Y substitution model.