Dual Role of AgNO₃ as an Oxidizer and Chloride Remover toward Enhanced Combustion Synthesis of Low-Voltage and Low-Temperature Amorphous Rare Metal-Free Oxide Thin-Film Transistors

SnO2 transistors show great promise as an alternative to existing In2O3-based transistors, considering their abundance and similar electronic properties. However, they suffer from highly negative on-voltages, large subthreshold swings, and high processing temperatures. One of the reasons for this is the residual chloride in the SnO2 film, which negatively impacts the transistor by increasing the defects or acting as a dopant, thereby shifting the turn-on voltage negatively and increasing the subthreshold swing. Herein, we present a facile method of producing Si x Sn y O films with fewer chloride impurities, which can be used in high-performance, solution-processed TFTs. We employed AgNO3 as an oxidizer for a low-temperature combustion reaction at 300 degrees C, which simultaneously acts as a chloride remover. We successfully reduced the turn-on voltage from -35.0 to -0.7 V using this route. The subthreshold swing was decreased from 2.91 to 0.32 V/dec using the same Sn concentration. The highest mobility obtained was 1.92 cm(2)/(V s) from the 0.25 M Sn precursor at a low drain voltage of 0.1 V. This method can be used as a general route for fabricating solution process-based SnO2 TFTs and further expanding its application to flexible devices via low-temperature combustion.