Photochemically activated flexible metal-oxide transistors and circuits using low impurity aqueous system

High mobility flexible metal-oxide thin-film transistors and circuits have been fabricated on an ultrathin plastic substrate using environmentally benign aqueous solution system and low-temperature photochemical activation process (∼150 °C). Results show that the indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) fabricated from nitrate-based precursors in aqueous solution outperform the devices from acetate-based precursors in alcohol solution. Here, IGZO TFTs and seven-stage ring oscillators are demonstrated on a 3∼5 μm-thick polyimide substrates with an average mobility of >6.9 cm²/V-s, subthreshold slope of ∼0.14 V/decade, and oscillation frequency of ∼340 kHz corresponding to 210 ns of propagation delay per stage at a supply bias of 20 V.