Characterization of β-Ga2O3 epitaxial films grown on MgO (111) substrates by metal-organic chemical vapor deposition

Gallium oxide (Ga2O3) films were prepared on MgO (111) substrates at different temperatures by metal-organic chemical vapor deposition (MOCVD). The film deposited at 650 °C exhibited the best crystallinity with a monoclinic structure (β-Ga2O3). Structure analysis revealed an epitaxial relationship of β-Ga2O3 (2¯01) ‖ MgO (111) with β-Ga2O3 [010] ‖ MgO 〈110〉 and six-fold rotation domain structure was existed inside the film. A schematic diagram was proposed to explain the structure relationship between the film and the substrate. The average transmittance of the films in the visible wavelength range exceeded 91%. The optical band gap of the films deposited at 550, 600, 650 and 700 °C were 4.94, 4.90, 4.79 and 4.86 eV, respectively.