OXYGEN DIFFUSION THROUGH DIELECTRICS - A CRITICAL PARAMETER IN HIGH CRITICAL-TEMPERATURE SUPERCONDUCTORS MULTILAYER TECHNOLOGY

We have studied the relative diffusion rates of oxygen through dielect ric/buffer layers used in high critical temperature superconducting mu ltilayer structures. Epitaxial bilayer films of dielectric (CeO2, LaGa O3, NdGaO3, LaAlO3, MgO, SrTiO3, LaLiTi2O6, or LaNaTi2O6) on YBa2Cu3O7 -delta (YBCO) have been deposited onto (001) oriented single-crystal M gO substrates using pulsed laser deposition, These bilayers have been investigated for oxygen diffusion over the temperature range 350 to 65 0 degrees C by postdeposition annealing the films for 20 min in 0.5 at m of O-18 enriched molecular oxygen gas. Secondary ion mass spectrosco py was used to depth profile the relative concentration of O-18 to O-1 6 in each bilayer, Compared to YBCO, the dielectrics MgO, SrTiO3, LaLi Ti2O6, and LaNaTi2O6 are relatively slow diffusers, while CeO2, LaGaO3 , NdGaO3, and LaAlO3 are relatively fast diffusers.