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

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.