Optimization of Dual-Fuel Combustion Synthesis for Rapid Formation of Solution-Processed Metal-Oxide Thin-Film Transistors

Abstract

Solution processing of metal-oxide semiconductors has received significant attention in various fields of electronics owing to its advantages such as simple fabrication process, large-area scalability, and facile stoichiometric tunability. However, the conventional sol–gel route requires a relatively long annealing time to obtain a low-defect film with high density and sufficient amount of metal–oxygen–metal bonding state, which prevents implementation in cost-effective continuous manufacturing. Here, we report rapid formation of solution-processed oxide semiconductors by employing a dual-fuel-based solution combustion synthesis route. In particular, by optimizing the ratio of dual fuels of acetylacetone and 1,1,1-trifluoro-acetylacetone (molar ratio of 7:3), high-performance indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs) could be fabricated at 350 °C with the annealing time as short as 5 min (In:Ga:Zn = 0.68:0.1:0.22). Based on spectroscopic analysis, it was found that the dual fuels enabled rapid formation of the metal–oxygen–metal lattice structure with low defective oxygen bonding states. The IGZO TFTs fabricated with an optimized fuel ratio exhibited average field-effect mobilities of 1.11 and 3.69 cm2 V–1 s–1 with annealing times of 5 and 20 min, respectively (averaged in 9∼12 devices). Also, in the case of the 5 min annealed device, the threshold voltage was −0.48 ± 1.96 V, showing enhancement-mode operation. Furthermore, the device showed good stability against both positive gate bias stress and negative gate bias stress conditions with small threshold voltage shifts of −1.28 and – 1.28 V in 5760 s, respectively.