MODIFICATION OF THE X-RAY PHOTOEMISSION SPECTRUM OF IN-SITU DEPOSITEDTHIN-FILMS OF Y1BA2CU3O7-Y FOR VARIOUS OXYGEN TREATMENTS

We have grown thin films of the Y1Ba2Cu3O7-y superconductor onto MgO a nd LaGaO3 substrates by off-axis sputtering. The films were all deposi ted under the same conditions, but were cooled in various oxygen press ures resulting in films with superconducting transition temperatures f rom 85 K to nonsuperconducting. The samples have been examined by x-ra y photoemission spectroscopy without exposing the samples to air. We h ave characterized the core levels of Y, Ba, Cu, and O and the Auger pa rameter of Ba, Cu, and O as a function of the oxygen pressure used dur ing cooldown. We find that the core lines sharpen and the Auger parame ter for copper reduces as the oxygen pressure is decreased. We interpr et this latter result as a possible change in the valence state of cop per. We also see a variation in the valence structure.