Investigation of low operation voltage InZnSnO thin-film transistors with different high-k gate dielectric by physical vapor deposition

Amorphous Indium-Zinc-Tin-Oxide thin-film transistors (a-IZTO TFT) using different types of high-k materials (like HfO₂, ZrO₂ and Al₂O₃) as gate dielectric are studied in this work. All gate dielectric films were deposited by physical vapor deposition (PVD) process for better composition control. Compared with the traditional SiO₂ gate insulator, a high-k gate dielectric can reduce the operation voltage of TFT device significantly. The TFT device with ZrO₂ gate insulator exhibits a small subthreshold swing of 0.126 V/decade, high field-effect mobility of ~40.7 cm²/Vs, low threshold voltage of −0.05 V, and large On/Off current ratio of ~1.01 × 10⁷. The mechanisms for electrical improvements are also investigated. These results demonstrate the potential application of PVD-deposited ZrO₂ thin film as a promising gate dielectric in oxide-based thin-film transistors.