Solution-Processed Amorphous In–Zn–Sn Oxide Thin-Film Transistor Performance Improvement by Solution-Processed Y2O3 Passivation

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.