Microstructural characterization of YBa2Cu3O 7-δ thin films on SrTiO3 using four-axis X-ray diffraction

Microstructural characteristics of YBa₂Cu₃O _7-δ thin films on SrTiO₃ have an important influence on their physical properties. Four-axis X-ray diffraction methods have been used to characterize textured and nontextured phases in several YBa₂Cu₃O_7-δ thin films deposited on single-crystal SrTiO₃. The type of epitaxial orientation of a- and c-axis textured films has been analyzed by tilting the specimen and observing the distribution of YBa₂Cu₃ O_7-δ {102} plane X-ray intensities over 95% of the reciprocal lattice hemisphere. The ratio of a- to c-axis material was determined. Several films were found to contain nonepitaxially oriented YBa₂Cu₃O_7-δ, Y₂ BaCuO₅, and BaCuO₂. Methods for quantifying the amounts of these random phases are discussed. The existence of stacking faults, such as those caused by the presence of extra Cu-O planes in YBa₂Cu₃O_7-δ, can sometimes manifest itself as a broadening and shifting of diffraction peaks. Consistent with the X-ray data, the stacking faults are readily seen in high-resolution electron microscopy images