Redox Chloride Elimination Reaction: Facile Solution Route for Indium‐Free, Low‐Voltage, and High‐Performance Transistors

Abstract

Solution‐processed oxide semiconductor and dielectric thin films have been widely studied for achieving flexible, high‐performance, and low‐power electronics and circuits. In this report, high‐k HfO2 dielectrics and amorphous ZnSnO (ZTO) semiconductors are synthesized via a simple and facile redox reaction by introducing perchloric acid (HClO4, PA) as oxidizer to eliminate the Cl residuals. Thermogravimetric analysis indicates that the thermal decomposition of PA‐involved HfCl4(PA‐HfO2) xerogel is completed at 350 °C, whereas the decomposition temperature of pristine HfCl4 xerogel is higher than 450 °C. The optical, structural, morphological, compositional, and electrical properties of PA‐HfO2 and the pristine HfO2 dielectric films are investigated systematically. Meanwhile, by using chloride elimination reaction, PA‐ZTO semiconducting thin films are fabricated at various temperatures and their applications in thin‐film transistors (TFTs) are examined. Furthermore, the optimized PA‐ZTO channel layer is fabricated on PA‐HfO2 dielectric. The resulting device exhibits high electrical performance and operational stability at a low voltage of 2 V, including high saturation mobility of 13.2 cm2 V−1 s−1, small subthreshold slope of 70 mV dec−1, current ratio of 108, and threshold voltage shift of 0.05 V under positive bias stress for 3000 s. Finally, a low‐voltage resistor‐loaded inverter is built using PA‐ZTO/PA‐HfO2 TFT, exhibiting a linear relationship between supplied voltage and gain voltage and a maximum gain of 11 at 2.5 V.