Selective deposition of epitaxial YBCO films on Al2O3/CeO2 substrate and titanium oxide mask applicable for patterning of stable microbridges

Crystallographic and physical properties of epitaxial YBa2Cu3Ox (YBCO) films selectively grown on the titanium oxide mask and CeO2 buffer layer are presented. The deposition process was realized on a sapphire single-crystal substrate. It took place as an in situ deposition from the moment when a system, substrate + CeO2 buffer + metallic Ti film, was available. It involved plasma oxidation of Ti to titanium oxide at 750 deg. C and deposition of YBCO at the same temperature, but in a gas mixture: argon + oxygen. Epitaxial thin YBCO layers were deposited by magnetron sputtering. The evaporated titanium oxide mask on CeO2 showed no significant incorporation of YBCO slab, while deposition of YBCO on the CeO2 buffer layer produced a superconducting film. These properties predetermine the use of the stable TiO2 mask for patterning of lasting submicrometre bridges. Estimation of the oxygen content in YBa2Cu3Ox from the x-ray pattern is also briefly described. (author)