YBA2CU3O7-X FILMS ON YTTRIA-STABILIZED ZRO2 SUBSTRATES : INFLUENCE OF THE SUBSTRATE MORPHOLOGY

c‐axis‐oriented YBa2Cu3O7−x (YBCO) thin films were laser deposited on (001) yttria‐stabilized ZrO2 (YSZ) substrates with different surface morphologies. The in‐plane orientation of the films on smooth substrates was sensitive to the deposition conditions, often resulting in mixed orientations. However, a strongly dominating [110]YBCO//[110]YSZ orientation was obtained at a deposition temperature of 770 °C. Films on substrates with surface steps, induced by depositing a homoepitaxial buffer layer or by thermally annealing the substrate, had a [110]YBCO//[100]YSZ orientation when deposited at the same temperature. It was concluded that the [110]YBCO//[100]YSZ orientation was promoted by a graphoepitaxial mechanism. Films prepared under identical conditions on smooth and stepped substrates grew with extended c axes on the former. It is proposed that the extension can be induced by disorder, invoked by a low oxygen pressure and a low density of adsorption sites. The disorder may be eliminated by either an inc...