Structural and optical properties of Al sub(2x)In sub(2-2 x)O sub(3) films prepared by metal-organic chemical vapor deposition

Tunable band gap Al sub(2x)In sub(2-2x)O sub(3) 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 degree 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 In sub(2)O sub(3) structure with Al sub(0.2)In sub(1.8)O sub(3) (110)[Verbar]MgO (110), while the films with x= 0.3 and 0.5 had polycrystalline structures, and the sample prepared with x= 0.9 exhibited gamma -Al sub(2)O sub(3) 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.