Gallium (III) oxide Ga2O3 is emerging in the field of wide bandgap semiconductor for various applications such as solar-blind photodetectors et al. because of its wide bandgap. For this reason, the optical properties of Ga2O3 by sol-gel method are analyzed. Ga2O3 thin films are prepared by spin coating method. The annealing temperature to make α-Ga2O3 is in the range of 450°C-550°C, where after 550°C, β-Ga2O3 is obtained as reported in reviewed works. Therefore, annealing temperatures of samples are set at 500°C, 700°C and 900°C. X-ray diffraction is performed to characterize the structure of the sample. The optical bandgap of Ga2O3 is calculated based on the transmittance value measured from UV-Visible spectrophotometer, which range from 4.8eV to 5.0eV.
