電総研, 山形大工A
@カテリン・デベロス, 山崎 裕文, 澤彰仁, 中川愛彦, 大嶋重利A, 向田昌志A
We investigated the microstructure of epitaxial c-axis oriented YBCOfilms laser-deposited onto CeO2-buffered Al2O3 using transmission electronmicroscopy (TEM), scanning electron microscopy (SEM), and x-ray diffraction(XRD). As investigated by atomic force microscopy (AFM), the CeO2 film hasa rough surface morphology characterized by longitudinal islands. However,cross-sectional TEM results revealed a smooth interface between the YBCO andCeO2 layers. TEM and SEM results show that the YBCO films contain surfaceoutgrowths of approximately 0.3 ‾ 1.0 mm in size well interspersed across arelatively smooth background. The surface outgrowths, most of which areassociated with misoriented YBCO, typically originate at a film thickness ‾50-100 nm, i.e., far from the YBCO/CeO2 interface. The microscopiccomposition of the outgrowths was investigated using scanning Auger electronspectroscopy (AES) and energy dispersive analysis by x-ray (EDAX). Resultsshow that the composition did not deviate significantly from that of theunderlying YBCO (123) matrix, although a few outgrowths were found to beslightly rich in Cu and deficient in Y. Inspite of the presence of theseoutgrowths, critical current density Jc measurements yielded typically highvalues in the order of 106 A/cm2.