Oxygen tracer diffusion through BaF2 and MgO overcoats on YBa2Cu3O7−Δ

Abstract
The movement of oxygen through MgO and BaF2 overcoats on YBa2Cu3O7−Δ has been studied using 18O tracer diffusion techniques. By analyzing the 18O and 16O signals from secondary‐ion mass spectrometry depth profiles, the motion of small concentrations of oxygen in both insulating and oxygenated hosts has been tracked. BaF2 was found to be transparent to oxygen diffusion while MgO blocked its motion during 10 min 500–600 °C anneals. Uncovered YBa2Cu3O7−Δ films were also found to exchange up to 90% of their oxygen during similar anneals. These results have important ramifications for reoxygenation steps during device fabrications.