Increase of achievable film thickness by UV-lamp irradiation in a fluorine-free metal-organic deposition process of YBa2Cu3O7

We have studied the effects of UV-lamp irradiation in a fluorine-free metal-organic deposition (FF-MOD) process for epitaxial YBa₂Cu₃O₇ (YBCO) films. We found that the irradiation dramatically improves the elemental homogeneity in a precursor film, and increases the thickness of epitaxial growth by twofold with respect to the same process without irradiation. We obtained a 1.05-μm-thick epitaxial YBCO film, which is thickest for FF-MOD processes. A possible reason for the improved element uniformity is simultaneous decompositions of three metal-organic ingredients by photons, which strongly reduce grain growths in a precursor film that have been known as an unavoidable feature in the conventional all-pyrolytic MOD.