Solution-Processed Amorphous In–Zn–Sn Oxide Thin-Film Transistor Performance Improvement by Solution-Processed Y₂O₃Passivation

Abstract

We report the effect of water-based Y ₂ O ₃ passivation on the performances of solution-processed amorphous indium-zinc-tin oxide (a-IZTO) thin-film transistors (TFTs) employing a solution-processed ZrO ^x gate insulator. The Y ₂ O ₃ passivation increases the saturation mobility (μ _sat ) and the current ratio (I _ON / _OFF ) from 1.64 ± 0.70 to 4.75 ± 0.87 cm ² V ^-1 s ^-1 and from 10 ⁸ to 10 ⁹ , respectively, and decreases the hysteresis voltage (V _H ), subthreshold swing, and threshold voltage (V _th ) from 0.09 ± 0.09 to 0 V, from 147.44 ± 44.55 to 114.29 ± 15.06 mV/decade, and from 0.54 ± 0.21 to 0.42 ± 0.23 V, respectively. The threshold voltage shift under positive gate bias stress is also reduced from 1.78 to 0 V. The improvements can be explained by the diffusion of Y into a-IZTO. Yttrium concentration in the a-IZTO active layer is found to be ~16 at.%, which leads to the decrease in oxygen vacancy and hydroxyl group concentrations, and to the increase in M-O-M bond concentration at the a-IZTO/ZrO _x and a-IZTO/Y ₂ O ₃ interfaces.