Preparation of YBa₂Cu₃O_7-x films on cap-layer-buffered MgO substrates using precursor films deposited from Y, BaF₂ and Cu

YBa₂Cu₃O_7-x (YBCO) is prepared by low-oxygen-pressure annealing of precursor films which are deposited from Y, BaF₂ and Cu sources at room temperature. In the annealing process, pure oxygen gas is introduced into the reaction chamber. The other gases, for example, water vapor or nitrogen gas, are not intentionally introduced. We previously reported that it is difficult to control the in-plane alignment YBCO films on MgO substrates. Therefore, a single cap layer (BaSnO₃) or double cap layers (CeO₂/BaSnO₃) are deposited on the MgO substrate. Subsequently, the YBCO films are prepared on the cap-layer-buffered MgO substrates. We evaluated the crystallinity and the film growth of the YBCO films on single-cap-layer-buffered and double-cap-layer-buffered MgO substrates.