Impact of oxygen vacancy on the photo-electrical properties of In₂O₃-based thin-film transistor by doping Ga

In this study, amorphous indium gallium oxide thin-film transistors (IGO TFTs) were fabricated by co-sputtering. Three samples with different deposition powers of the In₂O₃ target, namely, sample A with 50W deposition power, sample B with 60Wdeposition power, and sample C with 70 W deposition power, were investigated. The device performance revealed that oxygen vacancies are strongly dependent on indium content. However, when the deposition power of the In₂O₃ target increased, the number of oxygen vacancies, which act as charge carriers to improve the device performance, increased. The best performance was recorded at a threshold voltage of 1.1 V, on-off current ratio of 4.5 → 10₆, and subthreshold swing of 3.82 V/dec in sample B. Meanwhile, the optical properties of sample B included a responsivity of 0.16 A/W and excellent ultraviolet-to-visible rejection ratio of 8 → 10₄. IGO TFTs may act as photodetectors according to the results obtained for optical properties.