RBS STUDY OF INSITU GROWN BISRCACUO FILMS

BiSrCaCuO thin films have been grown in situ on MgO single crystals by pulsed laser deposition under 0.1 mbar oxygen pressure, the substrate temperature being around 700-degrees-C. These films are nearly pure 2212 phase, highly textured with a full c-axis orientation, and Rutherford backscattering spectrometry (RBS) in channeling geometry has been used to obtain precise information on their crystallinity. Although the X(min) values were found higher (about 35%) than those measured on bulk single crystals, they show partial epitaxy of the films, which was not observed with post annealed films. The comparison of backscattering yield in random and aligned orientations evidences the fact that all the cationic elements behave in a similar way in the channeling experiments, while differences are observed for the oxygen species according to their precise location in the network. These in situ grown films were found very sensitive to the ion irradiation, and showed large dechanneling effect with increasing ion dosis.