Sol-gel-based metal-oxide thin-film transistors for high-performance flexible NMOS inverters

High-performance metal-oxide thin-film transistors (oxide-TFTs) with high-k zirconium dioxide (ZrO2) dielectric and indium-gallium-zinc oxide (IGZO) semiconducting films were developed on flexible polyimide substrates. The flexible IGZO-TFTs fabricated using a simple and effective sol-gel-based solution -process combined with oxygen-enriched consecutive annealing at 200 & DEG;C, exhibited a high field-effect mobility of 13.6 cm(2) V-1 s(-1) at 5 V, on/off ratio of 1.05 x 10(6), gate leakage current of 2.7 x 10(-11) A, and threshold voltage of 0.44 V. The effects of O-2 annealing on the film quality of the sol-gel-based ZrO2 and IGZO were investigated by analyzing the crystallinity, morphology, and degree of metal-oxygen bonding states. Temperature-dependent steady-state direct-current measurements over the temperature range of 90-300 K, and time-domain non-quasi-static transient measurements with a minimized resistance-capacitance time constant were performed. Thus, the activation energy, density of states, interface trap density, and velocity distribution were determined to investigate the charge transport mechanism responsible for the high performance of the oxide-TFTs proposed in this study. An enhancement-load-type N-channel metal-oxide semiconductor (NMOS) inverter consisting of two oxide-TFTs fabricated via O-2 annealing was demonstrated. The flexible NMOS inverter exhibited a high gain of 10.8 at 5 V and outstanding mechanical stability against 10,000 cycles of bending stresses at a strain of 30% without a passivation or buffer film.(c) 2022 Elsevier B.V. All rights reserved.