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.