Preparation and characterization of YBa2Cu3O7−x high Tc superconducting thin films deposited by S-gun sputtering

We have prepared YBa₂Cu₃O_7?x high T_c superconducting (HTS) thin films on (100) yttria-stabilized zirconia (YSZ) and LaAlO₃ (LAO) substrates, using a 2 kW S-gun in an off-axis mode. By varying the temperature of the substrates, films with a axis and c axis orientations were readily obtained. The X-ray diffraction pattern and Laue pattern confirmed that films with a axis orientation exhibited a single-crystal texture. All films had a good mirror-like surface. For films grown on YSZ substrates, scanning electron microscopy (SEM) revealed a clear distinction between the surfaces of the films grown at various temperatures (520–780°C). Films grown on LAO substrates exhibited even smoother and flatter surfaces. The SEM changes will be discussed in correlation with J_c. The best HTS thin films were obtained on LAO substrates at a temperature of 820°C, with T_c=89 K and J_c=1×10⁶ A cm^-2 (77 K).