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 (
$\sim 150$
°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\sim 5~\mu $
m-thick polyimide substrates with an average mobility of
$>6.9~\mathrm{cm}^{2}$
/V-s, subthreshold slope of
$\sim 0.14$
V/decade, and oscillation frequency of
$\sim 340$
kHz corresponding to 210 ns of propagation delay per stage at a supply bias of 20 V.