Structural and optical properties of Al2xIn2−2xO3 films prepared by metal-organic chemical vapor deposition

Abstract

Tunable band gap Al_2xIn_2−2xO₃ films with different compositions x[Al/(Al + In) atomic ratio] were grown on MgO (110) substrates by the metal organic chemical vapor deposition (MOCVD) method at a temperature of 700 °C. The effects of different Al concentrations on the structural and optical properties of the obtained films were discussed in detail. The film deposited with an Al concentration of x = 0.1 showed single crystalline bixbyite In₂O₃ structure with Al_0.2In_1.8O₃ (110)‖MgO (110), while the films with x = 0.3 and 0.5 had polycrystalline structures, and the sample prepared with x = 0.9 exhibited γ-Al₂O₃ structure. The transmittances of all the samples exceeded 80% in the visible region. The optical absorption edges of the films shifted to short wavelength, and the bandgap of the prepared films could be monotonously modulated from 3.73 eV to 5.82 eV as the Al concentration increased from 0.1 to 0.9.