A buffer layer is indispensable for preventing chemical reactions between high-temperature superconducting thin films and R-Al
2O
3. CeO
2 is a promising buffer layer. However, when a CeO
2 buffer layer with a thickness of more than 50 nm is sputter-deposited onto a R-Al
2O
3 substrate, grains with facets grow and a high-quality EuBa
2Cu
3O
7-δ (EBCO) thin film do not grow on the buffer layer. In order to fabricate a flat and facet-free CeO
2 buffer layer and a high-quality EuBa
2Cu
3O
7-δ (EBCO) thin film, we examined the effects of off-center distance (
Doff) and substrate temperature (
Ts) of the CeO
2 buffer layer on the properties of CeO
2 buffer layers and EBCO thin films.
Doff was defined by the distance from the on-center position to the off-center position. The deposition rate (
Rd) was controlled by
Doff. A 300-nm-thick CeO
2 buffer layer and a 150-nm-thick EBCO thin film were prepared by RF and DC magnetron sputtering, respectively. The surface morphology of CeO
2 buffer layer was dependent on
Ts and
Doff. At
Ts = 650°C and
Doff = 30 mm, minute grains grew. When
Doff was increased to 50 mm, grains with (111) facet planes grew. The surface roughness (
Rz) of the CeO
2 buffer layer rapidly increased as
Doff was increased. The orientation of the EBCO thin film was dependent on the
Doff of the buffer layer. At
Doff = 0 ∼ 30 mm, only (00
l) peaks of an EBCO thin film were observed in X-ray diffraction patterns. Typical rectangular grains were observed on the surface of the thin film. At
Doff values over 40 mm, (110) or (103) peaks, in addition to (00
l) peaks, were observed. At
Doff = 30 mm, the EBCO thin film exhibited a critical temperature (
Tce) of approximately 89 K and a critical current density (
Jc) of approximately 3.6 MA/cm
2.
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