Low-Voltage a-InGaZnO Thin-Film Transistors With Anodized Thin HfO2 Gate Dielectric

Low-voltage amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with thin HfO2gate dielectric grown by anodic oxidation (anodization) method are investigated. The morphological and electrical properties of the anodized thin HfO2film are studied. It is shown that the as-grown HfO2film with an equivalent oxide thickness of 3.8 nm has a low leakage current density of 3.6 × 10-8A/cm2at 1 MV/cm and high dielectric constant of ~21. The room-temperature fabricated a-IGZO TFTs with the anodized HfO2gate dielectrics exhibit a low threshold voltage of -0.15 ± 0.08 V, small subthreshold swing value of 109 ± 4 mV/decade, reasonable saturation mobility of 8.1 ± 0.2 cm2/Vs, and an ON/OFF current ratio exceeding 1 × 107.