Comparison of electrical performances of water and organic solvent-based amorphous indium-gallium-zinc-oxide thin-film transistors

Water and organic-based amorphous InGaZnO thin-film transistors (a-IGZO TFT) were fabricated and their electrical performances were analyzed. By comparing the threshold voltage, subthreshold slope, and field-effect mobility with scaling characteristics, we found that the a-IGZO TFT performances were mainly dependent on the solvent types and stirring times of the precursor solution. In addition, it is shown that the field-effect mobility values follow the Poole-Frenkel mobility model for water-based TFTs when the stirring time is under 24 h indicating that there are large defect density of states that degrade the field-effect mobility. When the stirring time is sufficiently long for the water-based sample, the sample shows superior field-effect mobility compared to the organic-based one, which is attributed to the high annealing efficiency of the water-based IGZO active layer compared to the organic-based one. (C) 2019 The Japan Society of Applied Physics