Eco-Friendly, Water-Induced In2O3 Thin Films for High-Performance Thin-Film Transistors and Inverters
Solution-driven metal–oxide semiconductors have recently received much attention as a viable option for low-cost, flexible electronic devices. In this paper, a simple, environmentally friendly aqueous solution method has been adopted to deposit an ultrathin In<sub>2</sub>O<sub>3</sub> semiconductor layer with a thickness of about 7 nm at low temperature. Then, in combination with the advantages of atomic layer deposition (ALD) technology, an ultrathin aluminum oxide dielectric layer of about 20 nm was prepared to fabricate high-performance In<sub>2</sub>O<sub>3</sub>/Al<sub>2</sub>O<sub>3</sub> thin-film transistor (TFT) devices. The device with optimized annealing temperature of 280 °C has demonstrated an excellent electrical performance, including a high saturation mobility of 11.85 cm<sup>2</sup> · V<sup>−1</sup> · s<sup>−1</sup>, a large ON/OFF current ratio of 10<sup>6</sup>, a low threshold voltage of 0.12 V, a small hysteresis voltage of 0.05 V, and a small density of interface state of <inline-formula> <tex-math notation="LaTeX">$\textsf {1.97} \times \textsf {10}^{\textsf {12}}$ </tex-math></inline-formula> cm<sup>−2</sup>, respectively. To demonstrate the potential of In<sub>2</sub>O<sub>3</sub>/AlO<sub><italic>x</italic></sub> TFT toward more complex logic applications, the unipolar inverter was further constructed and exhibited a high gain of 5. Importantly, all these device parameters were obtained at an ultralow operating voltage of 2.5 V. As a result, it can be inferred that the water-induced In<sub>2</sub>O<sub>3</sub> TFTs based on ALD-derived Al<sub>2</sub>O<sub>3</sub> dielectrics have a potential application as a promising alternative for low-cost, low-power consumption, and large-area environmentally friendly oxide flexible electronics.