The use of combinatorial aerosol-assisted chemical vapour deposition for the formation of gallium-indium-oxide thin films

Abstract

We describe a novel combinatorial aerosol-assisted chemical vapour deposition (cAACVD) technique to deposit gallium-doped indium oxide thin films. The oxide films, Ga_xIn_2-xO₃ (where x = 0.4–1.6) were deposited within composition graduated films from the aerosol-assisted CVD of GaMe₃, InMe₃ and HOCH₂CH₂OMe. Amorphous Ga₂O₃ was deposited closest to the inlet from the bubbler containing GaMe₃/HOCH₂CH₂OMe whereas crystalline In₂O₃ was grown on the substrate closest to the inlet from the bubbler containing InMe₃/HOCH₂CH₂OMe. A range of gallium-indium-oxide compositions, Ga_xIn_2-xO₃, were deposited on the substrate in the region between the two inlets. This allowed for a systematic investigation on the effect of doping on gallium and indium oxide and a direct relationship between composition and conductivity of the films was observed. The films were characterised viaX-ray diffraction (XRD) mapping, energy dispersive X-ray analysis (EDXA), scanning electron microscopy (SEM) and conductivity measurements. The lattice parameters for crystalline films are sensitive to composition and were determined to range from a = 10.091 to 10.057 Å. This is to our knowledge the first time that a combinatorial aerosol-assisted CVD method has been described. This provides a rapid route to investigate the effect of a dopant on the functional properties of a wide range of materials. Moreover, since it is a solution-based technique, films with a range of compositions could be deposited even if volatile precursors are not available.