MOD growth of epitaxial cerium oxide buffer layer on LAO substrates for fabrication of c-axis oriented YBCO

Epitaxial cerium oxide (CeO2) buffer layer has been grown on lanthanum aluminate (LAO) single crystal substrates for fabrication of c-axis oriented YBa2Cu3O72x (YBCO). Precursor solution of cerium acetylacetonates with viscosity of 0.6 centipoises was spin coated on the 1 × 1 cm area LAO substrates. The calcination was carried out by very slow ramp (18C per minute) until the final temperature of 5008C in oxygen flow to remove most of the organic compounds. The final heat treatment has been done at 7808C by a ramp of 208 per minute in gas flow of mixed argon–oxygen with 5 Pa partial pressure of oxygen. The thickness of the deposited CeO2 buffer layer was 20 nm. Then, 100 nm thick YBCO film was deposited by sputtering on the CeO2 buffered LAO substrate. Another film with same deposition conditions was also fabricated on the bare LAO crystal for comparison. The scanning electron microscopy (SEM) and X-ray diffraction characterisations show a/b axis YBCO decreases significantly when using the CeO2 buffered LAO instead of the bare LAO. R–T and Jc measurements of the samples are also reported. Superconducting transition width of the fabricated film on the substrate with CeO2 buffer layer is less than 0.4 K and the Jc of the fabricated film is above 3.5 MA/cm .