Raman and XRD characterisation, microstructure and microwave loss in YBCO 123 thin films

Several YBa2Cu3O7-delta thin films grown by e-beam co-evaporation were chosen because of the variation of microstructural disorder between them. Raman microscopy and x-ray diffraction were used to determine the degree of oxygen and structural disorder in the films. Transmission electron microscopy was used to examine microtwinning and a axis coverage. The films were grown under different conditions of temperature and oxygen partial pressure and apart from other microstructural features they also show different levels of cation disorder. The microwave loss and power dependence of the surface impedance were also studied. As the films exhibited a range of microstructual properties it was not possible to make a direct correlation between microwave loss and strucural disorder. The study illuminates the problems associated with optimisation of films for good power handling capabilities.