Structural properties of Zn-substituted epitaxial thin-films

We optimized the deposition of thin-films using inverted cylindrical magnetron sputtering and report here a detailed structural study, especially in relation to crystal growth, associated surface morphology, precipitation and other secondary phases important for flux pinning. We find that the epitaxial quality of the Zn-substituted films is decreased compared with high-quality pure films prepared under identical conditions. The pure films have smoother surfaces, while those of Zn-substituted films contain pinholes and outgrowths. Secondary phases and a-axis grains were observed in the Zn-substituted films. precipitates with typical dimensions of 50 - 100 Å have been found in both pure and Zn-substituted samples. However, their density of about , observed in the pure films, is significantly reduced in the Zn-substituted films when increasing the Zn concentration up to 4%.