Improvement of the homo-biepitaxial YBCO film fabrication process on Yttrium Stabilized Zirconia

We present the results of the application of the dc magnetron sputtering modulation mode to fabricate YBCO homo-biepitaxial thin film Josephson junctions on Yttrium Stabilized Zirconia substrate. A 45° in-plane rotation of the grown YBCO films with respect to the substrate orientation is realized by using a thin YBCO buffer layer deposited at a temperature (~600 °C) lower than the optimal value (800 °C). The control of the in-plane orientation allows to form Josephson junctions between two YBCO superconducting region of the film with and without buffer layer. We obtained that the modulated deposition mode improves the crystalline in-plane orientation of YBCO on buffer layer/YSZ substrate, increases the grain size and decreases the film stress. The improved homo-epitaxial process was applied for fabrication of dc SQUID devices.