Printed, Highly Stable Metal Oxide Thin‐Film Transistors with Ultra‐Thin High‐κ Oxide Dielectric
Emanuel Carlos, Jaakko Leppäniemi, Asko Sneck, Ari Alastalo, Jonas Deuermeier, Rita Branquinho, Rodrigo Martins, Elvira Fortunato
Abstract
Abstract 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 cm 2 V −1 s −1 , a subthreshold slope <80 mV dec −1 , and a current ON/OFF ratio >10 6 . 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.