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 HfO
₂
gate dielectric grown by anodic oxidation (anodization) method are investigated. The morphological and electrical properties of the anodized thin HfO
₂
film are studied. It is shown that the as-grown HfO
₂
film with an equivalent oxide thickness of 3.8 nm has a low leakage current density of 3.6 × 10
^-8
A/cm
²
at 1 MV/cm and high dielectric constant of ~21. The room-temperature fabricated a-IGZO TFTs with the anodized HfO
₂
gate 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 cm
²
/Vs, and an ON/OFF current ratio exceeding 1 × 10
⁷
.