Printed, Highly Stable Metal Oxide Thin-Film Transistors with Ultra-Thin High-κ Oxide Dielectric

Lately, printed oxide electronics have advanced in the performance and low-temperature solution processability that are required for the dawn of low-cost flexible applications. However, some of the remaining limitations need to be surpassed without compromising the device electronic performance and operational stability. The printing of a highly stable ultra-thin high-κ aluminum-oxide dielectric with a high-throughput (50 m min⁻¹) flexographic printing is accomplished while simultaneously demonstrating low-temperature processing (≤200 °C). Thermal annealing is combined with low-wavelength far-ultraviolet exposure and the electrical, chemical, and morphological properties of the printed dielectric films are studied. The high-κ dielectric exhibits a very low leakage-current density (10⁻¹⁰ A cm⁻²) at 1 MV cm⁻¹, a breakdown field higher than 1.75 MV cm⁻¹, and a dielectric constant of 8.2 (at 1 Hz frequency). Printed indium oxide transistors are fabricated using the optimized dielectric and they achieve a mobility up to 2.83 ± 0.59 cm² V⁻¹ s⁻¹, a subthreshold slope <80 mV dec⁻¹, and a current ON/OFF ratio >10⁶. The flexible devices reveal enhanced operational stability with a negligible shift in the electrical parameters after ageing, bias, and bending stresses. The present work lifts printed oxide thin film transistors a step closer to the flexible applications of future electronics.