Eco-Friendly Fully Water-Driven Metal–Oxide Thin Films and Their Applications in Transistors and Logic Circuits

In this paper, a nontoxic and environmentally friendly water-driven (WD) route to prepare InZnO thin films with various molar ratio of In and Zn has been reported. The formation mechanisms and physical properties of InZnO thin films as a function of element molar ratio are investigated by various characterization techniques. By comparing the performance of InZnO/SiO
₂
thin-film transistors (TFTs) at different element molar ratio, the results indicate that the molar ratio of 2:1 (In:Zn) is the optimal choice. Based on the optimal molar ratio, fully WD InZnO/HfO
_x
TFT is fabricated and the excellent electrical properties are obtained at a low operating voltage of 5 V, including a higher field-effect mobility of 9.1 cm
²
V
^-1
s
^-1
, a larger ON-/OFF-state current ratio of 1.5×10
⁷
, a smaller subthreshold swing of 0.09 V/dec, and a smaller threshold voltage shift of 0.44 V after 5400-s bias stressing, separately. Finally, to further validate the feasibility of InZnO TFTs in complex logic circuits, an inverter is assembled based on the InZnO/HfO
_x
TFT, exhibiting a high gain of 8.8. More importantly, the excellent properties of InZnO/HfO
_x
TFT are achieved at a low-voltage stage, which stands for the great application prospects of WD TFTs in low-cost and excellent performance electronic devices.