The diffusion of O in thin films was investigated by performing resistivity measurements under isobaric and isothermal conditions, at an O pressure of 1mbar and at temperatures ranging from 650 to 1050K. No difference was found between the in-diffusion and out-diffusion processes. The activation energy for all of the measured samples was close to 1.5eV, and was attributed to diffusion on the ab-plane. It was found that the absolute values of the diffusivity depended upon the film morphology rather than the thickness. It was suggested that O propagated along the c-axis, via a network of defects, whereas its motion in the ab-plane was governed by vacancy-mediated chemical diffusion.

V.Dediu, F.C.Matacotta: Physical Review B, 1996, 54[22], 16259-63