OXYGEN DIFFUSION IN EPITAXIAL YBA2CU3O7-X THIN-FILMS

In situ resistance changes of YBa2Cu3O7-x thin films during deposition were investigated at four different substrate temperatures in the 560-700-degrees-C range. The shapes of the resistance curves with time and the measurement of deposition rates clearly indicated that the film grew epitaxially on the (100)SrTiO3 substrate at 700-degrees-C. Isothermal oxygen diffusion along the c-axis direction into the epitaxially grown YBa2Cu3O7-x thin films was investigated by monitoring in situ resistance changes in the 450-600-degrees-C range; the apparent diffusion coefficients were (3.1-6.3) x 10(-11) cm2/s. An Arrhenius plot of the diffusion coefficients in the 450-550-degrees-C range gave an activation energy of 0.33 eV for oxygen diffusion plus a tetragonal-orthorhombic phase transition.