Epitaxial growth of YBa2Cu3O7-δ superconducting thin films by DC magnetron sputtering using a partially melted sintered target

In situ epitaxially grown YBa2Cu3O7-δ (YBCO) thin films on (100)SrTiO3 substrates with high critical current Jc=3.4x106 A/cm2 (at 77 K) and low microwave surface resistance RS≤37 mΩ (at 77 K, 50.9 GHz) are fabricated by dc magnetron sputtering using a large partially melted sintered planar target. A comparatively large homogeneous composition region can be obtained. The X-ray diffraction, X-ray double crystal diffraction, and high resolution transmission electron microscopy (HRTEM) analyses show that our deposited YBCO thin films are single crystalline containing mosaic blocks. The influence of substrate quality on the orientation behaviour of the films is also discussed. A method to improve the surface quality of the SrTiO3 substrate, which improves the properties of the thin film, is presented. (orig.)