Effect of substrate and buffer layer materials on properties of thin YBa2Cu3O7-x films
High-temperature superconducting thin films (YBa2Cu3O7−x) are emerging in superconducting single photon detector (SSPD) research as a novel replacement for conventional and semiconductor detectors. The major hindrance for this is the degradation of the superconducting properties of YBa2Cu3O7−x (YBCO) thin film with reduction of its lateral and longitudinal dimensions (i.e., film thickness and width of the stripe). Furthermore, the surface of the film should be smooth to enable fabrication of the SSPD device. In order to improve the quality of YBCO thin films, we exploited various buffer layers (i.e., SrTiO3, CeO2, and PrBa2 Cu3O7) with thickness of 30 ± 5 nm. We have also investigated the properties of (65 ± 5-nm-thick) YBCO films grown simultaneously on different substrates (i.e., SrTiO3, LaAlO3, MgO, and yttrium stabilized zirconia). For some substrate/buffer material combinations, the surface morphology of the YBCO film has been effectively improved. Also, there was only a small or no degradation of their critical temperature values. These structures give a precursor for further development of fabrication technology for YBCO-based SSPD devices.