Structural and optical properties of heteroepitaxial beta Ga2O3 films grown on MgO (100) substrates

Gallium oxide (Ga2O3) films were deposited on MgO (100) substrates by metalorganic vapor phase epitaxy. Structure analyses showed that the films deposited at 550–700 °C were epitaxial β-Ga2O3 films with an out of plane relationship of β-Ga2O3(100)||MgO(100). The film deposited at 650 °C showed the best crystallinity and the microstructure of the film was investigated by high resolution transmission electron microscopy. A theoretical model of the growth mechanism was proposed and the in-plane epitaxial relationship was given to be β-Ga2O3[001]||MgO<011>. A four-domain structure inside the epitaxial film was clarified. The β-Ga2O3 film deposited at 650 °C showed an absolute average transmittance of 95.9% in the ultraviolet and visible range, which had an optical band gap of 4.87 eV.

► Beta Ga2O3 epitaxial films were deposited on MgO(100) substrate.
► A theoretical model of the growth mechanism was proposed.
► The transmittance of the film in the ultraviolet and visible region exceeded 95.9%.