Real-time study of oxygen in c-axis oriented YBa2Cu3O7-delta thin films using in situ spectroscopic ellipsometry

The oxygen transport process in c-axis oriented YBa2Cu3O7-delta thin films was investigated in real time during deposition and postdeposition oxidatio n using in situ spectroscopic ellipsometry (SE). Two transport regimes domi nated by oxygen out- and in-diffusion have been observed during deposition by ion beam sputtering at 700 degrees C. The effect of oxygen partial press ure on the extent of oxidation of as-deposited films has also been studied during the postdeposition cooling process. The thermodynamic stability of t he grown films was examined by real time SE during the postannealing proces s. The relaxation time for oxygen diffusion has been found to decrease with higher oxygen partial pressures. The imaginary part of the pseudodielectri c function <epsilon(2)> at an absorption peak was quantitatively correlated to the oxygen concentration. The pseudodielectric functions of oxygen defi cient YBa2Cu3O6 films in the temperature range from 27 to 700 degrees C hav e been modeled using Lorentz oscillators. (C) 1999 American Institute of Ph ysics. [S0021-8979(99)05224-X].