Distribution of Ag in Ag-doped YBa2Cu3O7-δ thin film prepared by dual-beam pulsed-laser deposition

Abstract

The Ag distribution in Ag-doped YBa2Cu3O7-δ (YBCO) thin films fabricated by dual-beam pulsed-laser deposition on SrTiO3 (100) substrates has been studied by Auger electron spectroscopy, microproton-induced x-ray emission, atomic force microscopy and scanning electron microscopy. All the results consistently show that Ag aggregated in the bar-like structures observed in the film. These bars are aligned along the a-b-axis or at 45° to the a-b-axis of the YBCO thin film. The main body of the long bars aligned with the a-b-axes of the film was found to be a combination of metallic Ag with other precipitates of YBCO film that may grow from the substrate surface to the YBCO film surface. There were other precipitates aggregating as well at the surface of these bars, such as oxides of Cu and Ba. The short bars that aligned along 45° to the a-b-axes of the film were found to be deficient in Ag but rich in Cu, Ba and O, which could be oxide precipitates of YBCO. The growth mechanisms of the two types of bars seem quite different.