Preparation of high-quality CuGa₂O₄ film via annealing process of Cu/β-Ga₂O₃

High-quality CuGa₂O₄ film has been successfully prepared on β-Ga₂O₃ (\( \bar{2}01 \)) single-crystal substrate via annealing method at 1050 °C temperature under air after evaporating Cu film. According to high-resolution X-ray diffraction measurement results, the crystallinity of CuGa₂O₄ film and epitaxial relationship between CuGa₂O₄ film and β-Ga₂O₃ (\( \bar{2}01 \)) substrate was confirmed. The CuGa₂O₄ film has the preferred [111] orientation and the full-width half-maximum of CuGa₂O₄ film of (222) peak is 0.228°. The CuGa₂O₄ (111) plane is parallel to the β-Ga₂O₃ (\( \bar{2}01 \)) plane (out-plane) and the CuGa₂O₄ [\( \bar{1}\bar{1}2 \)], and [110] directions are parallel to the β-Ga₂O₃ [102] and [010] directions (in-plane), respectively. In addition, the lattice mismatch between CuGa₂O₄ [111] and β-Ga₂O₃ (\( \bar{2}01 \)) substrate has also been calculated. These results suggest that high-quality and preferred orientation CuGa₂O₄ film can be prepared on β-Ga₂O₃ (\( \bar{2}01 \)) substrate with Cu film.