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

In this work, we develop a simple and eco-friendly water-inducement method for high-k yttrium oxide (YO_x) dielectric. To prepare YO_x thin films at low temperature, yttrium nitrate and deionized water were used as the source materials. No toxic organic materials were required in the YO_x coating process. The YO_x 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 YO_x 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.