STRUCTURE AND GROWTH OF YBA2CU3O7-DELTA THIN-FILMS ON MG2TIO4 (001) .2. SURFACE-MORPHOLOGY - SCANNING PROBE METHODS

Superconducting YBa2Cu3O7-delta (YBCO) thin films with T(c)onset up tp 88 K have been prepared on single-crystalline Mg2TiO4 substrate layers grown on MgO cleavage faces as shown in Part I. The orientation and morphology of the YBCO films have been characterized by X-ray diffraction, scanning electron microscopy and scanning probe methods. A series of YBCO films has been prepared at different substrate temperatures T(s) on Mg2TiO4 (001) layers from a single batch in order to optimize the growth conditions. Depending on T(s), YBCO (001), (100) and (103) growth structures have been detected by X-ray diffraction and scanning tunneling microscopy. The film growth in (001) orientation is characterized by growth spirals originating from screw dislocations, whereas growth in (100) and (103) orientations exhibits needle and platelet structures, respectively.