SURFACE AND INPLANE CHARACTERIZATION OF YBA2CU3O7 THIN-FILMS GROWN BY LASER ABLATION

We have used reflection high energy electron diffraction (RHEED) and oscillating crystal X-ray diffraction to analyze the surface and in-plane structural characteristics of YBa2Cu3O7 (YBCO) thin films that were grown in-situ by laser ablation onto substrates of (100) MgO and (100) SrTiO3. We obtain RHEED streaks, characteristic of atomically smooth surfaces and indicative of epitaxial order, for these thin films. Oscillating crystal diffraction also indicates that the YBCO film axes are collinear with the substrate axes. The films grown on (100) substrates are solely c-axis oriented (perpendicular to the plane of the film) as determined by theta-2-theta diffractometry and the FWHM of rocking curves about the (005) reflection are 0.3-degrees to 0.5-degrees for the best films on SrTiO3 substrates and 0.4-degrees to 0.6-degrees for films grown on MgO. Weissenberg photography allows us to determine the in-plane structure of some films grown on MgO that display anomalous surface features seen by RHEED and by scanning electron microscopy.