Reactive coevaporation of YBaCuO superconducting films

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 T_c's (R = 0) up to 90 K and J_c'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 T_c'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.