Crystal Orientation of Cubic NiO Thin Films Formed on Monoclinic β‐Ga2O3 Substrates

The crystal orientation relationship between cubic NiO and monoclinic β‐Ga2O3 in NiO thin films formed on , (010), and (001) β‐Ga2O3 substrates is investigated by X‐ray diffraction analysis and cross‐sectional transmission electron microscopy imaging. The NiO films formed on and (010) β‐Ga2O3 substrates satisfy the orientation relationships NiO (111) [] ‖ β‐Ga2O3 [010] and NiO [] ‖ β‐Ga2O3 (010) [001], respectively. In the NiO films on (001) β‐Ga2O3 substrates, the NiO plane near (133) is parallel to the (001) plane of β‐Ga2O3 under the relationship NiO [] ‖ β‐Ga2O3 [010]. In addition, NiO films also satisfy the relationship NiO (100) ‖ β‐Ga2O3 (100) in each case. That is, for each case of , (010), and (001) β‐Ga2O3 substrates, the relationship of NiO (100) [011] ‖ β‐Ga2O3 (100) [001] is confirmed, consistent with the orientation relationship reported previously for NiO films on (100) β‐Ga2O3 substrates. The crystal orientation relationship is discussed in terms of the atomic arrangement models of NiO and β‐Ga2O3.