Oxygen diffusion in YBa2Cu3O7-δ films with different microstructures

We have investigated the oxygen out- and in-diffusion in epitaxial c-axis oriented YBa2Cu3O7-delta films from isothermal four-point electric resistivity measurements, The films were grown by two different deposition methods: off-axis pulsed laser deposition (PLD) and hollow-cathode magnetron sputtering (HCMS). Chemical diffusion relaxation times have been determined for the out- and in-diffusion of oxygen at temperatures from 500 K up to 800 K. Both types of films yielded the same activation energy of about E-A = 1.1 eV for the diffusion processes. However, at the same temperature, differences in the diffusion relaxation times were observed, This difference results from the different morphologies and microstructures we have studied with scanning electron microscopy (SEM), Additionally, these results are compared to sputtered YBa2Cu3O7-delta films passivated by amorphous Si-C-H-O-N overlay films. The activation energy in these films was about 1 eV, and the diffusion relaxation times were much larger than in the samples without the overlay. (C) 1998 Elsevier Science B.V, All rights reserved.