Effects of Oxidants on the Bias-Stress Instabilities of In-Ga-Zn-O Thin Film Transistors Using HfO₂ Gate Insulator Prepared by Atomic Layer Deposition

We fabricated the In-Ga-Zn-O thin-film transistors using HfO₂ gate insulator prepared by atomic-layer deposition with different oxidants of H₂O and O₃ at 200 °C. While the device using H₂O showed almost no change in threshold voltage (V_th) even after 10⁴ s with bias-stresses, the device using O₃ showed the V_th shifts of-1.4 and +1.2 V under positive and negative bias stresses, respectively. Defect-related carrier generation model was suggested as a physical origin for the anomalous bias-stress instabilities and the related mechanisms, in which the incorporated hydrogens can interact with oxygen-related defects.