Growth and photocatalytic properties of gallium oxide films using chemical bath deposition

Gallium oxide (Ga₂O₃) thin films were fabricated on glass substrates using a combination of chemical bath deposition and post-annealing process. From the field-emission scanning electron microscopy and x-ray diffraction results, the GaOOH nanorods precursors with better crystallinity can be achieved under higher concentrations (≥0.05 M) of gallium nitrate (Ga(NO₃)₃). It was found that the GaOOH synthesized from lower Ga(NO₃)₃ concentration did not transform into α-Ga₂O₃ among the annealing temperatures used (400–600 °C). Under higher Ga(NO₃)₃ concentrations (≥0.05 M) with higher annealing temperatures (≥500 °C), the GaOOH can be transformed into the Ga₂O₃ film successfully. An α-Ga₂O₃ sample synthesized in a mixed solution of 0.075 M Ga(NO₃)₃ and 0.5 M hexamethylenetetramine exhibited optimum crystallinity after annealing at 500 °C, where the α-Ga₂O₃ nanostructure film showed the highest aspect ratio of 5.23. As a result, the photodegeneration efficiencies of the α-Ga₂O₃ film for the methylene blue aqueous solution can reach 90%.