Low driving voltage amorphous In-Ga-Zn-O thin film transistors with small subthreshold swing using high-κ Hf-Si-O dielectrics

Low driving voltage thin-film transistors (TFTs) were fabricated by integrating both a sputtered high-κ Hf-Si-O gate dielectric and an amorphous In-Ga-Zn-O active layer on a silicon substrate. The influence of postdeposition annealing (PDA) temperature for the Hf-Si-O gate dielectric on device performance was investigated. The 400 °C PDA Hf-Si-O/a-In-Ga-Zn-O TFT exhibits a low threshold voltage of 0.005 V, a small subthreshold swing (SS) of 0.11 V-dec^-1, a high saturation mobility of 12.7 cm ².V^-1.s^-1, and an acceptable current ratio of 3 × 10⁵. The low threshold voltage and small SS are attributed to the excellent gate control ability which allows the device to operate at 2.0 V for low power applications.