Depositions of In_2xGa_2-2xO₃-based films and their application in the fabrication of a thin-film transistor

Compositions of 0.2In2O3 + 0.8Ga2O3 and 0.4In2O3 + 0.6Ga2O3 were mixed and sintered at 1250°C to fabricate In0.4Ga1.6O3 and In0.8Ga1.2O3 targets, and RF sputtering method was used to deposit In0.4Ga1.6O3 and In0.8Ga1.2O3 films by introducing pure Argon during the deposition process. After In0.4Ga1.6O3 and In0.8Ga1.2O3 films were deposited, we used the X-ray diffraction pattern to analyze their crystalline properties, the ultraviolet-visible-infrared spectrophotometry to measure their transmittance spectra in the wavelength range of 200-800 nm, an X-ray photoelectron spectroscopy to find their composition variation, and a Hall equipment to measure their electrical properties, including the carrier concentration, the mobility, and the resistivity. We found that the absorption edges of In2xGa2-2xO3 films were shifted to higher wavelength as x value increased from 0.2 to 0.4. We also found that the Hall parameters of In0.4Ga1.6O3 film could not be measured because of its high resistivity. Therefore, In0.8Ga1.2O3 film was used to fabricate thin-film transistor (TFT), and the electrical properties of the fabricated TFT were also well investigated.