The orientational relationship between monoclinic β-Ga2O3 and cubic NiO

Abstract

The orientational relationship between β-Ga2O3 and NiO was studied by X-ray diffraction measurements and cross-sectional high resolution transmission electron microscopy. A β-Ga2O3 thin film was formed on a (100) NiO layer on a (100) MgO substrate by gallium evaporation in an oxygen plasma. It was found that the resulting β-Ga2O3 had a four-fold domain structure satisfying both (100) β-Ga2O3 ‖ (100) NiO and (010) β-Ga2O3 ‖ {011} NiO. A γ-Ga2O3 layer was observed at the interface between the β-Ga2O3 and the NiO. An NiO film was also formed on a (100) β-Ga2O3 single-crystal substrate by the sol–gel method. An epitaxial (100) NiO film was formed on a (100) β-Ga2O3 substrate, and satisfied (011) NiO ‖ (010) β-Ga2O3. The crystal orientations of β-Ga2O3 on (100) NiO and NiO on (100) β-Ga2O3 can be explained using atomic arrangement models of the (100) plane of NiO and the (100) plane of β-Ga2O3.