A water-induced high-k yttrium oxide dielectric for fully-solution-processed oxide thin-film transistors

• Water-inducement route was proposed to fabricate oxide TFT at low temperature.
• Metal nitrates and deionized water were used as the source materials.
• A UV-assisted pre-treatment was used prior to thermal annealing process.
• The In2O3/YOx TFT exhibits high performance compared with SiO2-based TFT.
• The In2O3/YOx TFT can be operated at an ultra-low voltage of 1.5 V.

In this work, we develop a simple and eco-friendly water-inducement method for high-k yttrium oxide (YOx) dielectric. To prepare YOx thin films at low temperature, yttrium nitrate and deionized water were used as the source materials. No toxic organic materials were required in the YOx coating process. The YOx thin film annealed at 350 °C showed a low leakage current density of 2 × 10−9 A/cm2 at 5 MV/cm and a large areal-capacitance of 448 nF/cm2 at 1 kHz. On the basis of its implementation as the gate dielectric, the fully-water-induced In2O3 TFT based on YOx exhibited a high field-effect mobility of 15.98 cm2/Vs, excellent subthreshold swing of 75 mV/dec, an on/off current ratio of 6 × 106, and a negligible hysteresis of 50 mV. The as-fabricated TFT operated at a low voltage (∼1.5 V) and showed high drain current drive capability, enabling oxide TFT with a water-induced high-k dielectric for use in backplane electronics for low-power mobile display applications.