In this study, a unique strategy for the improvement in aqueous solution-processed indium zinc oxide (IZO) thin film transistor (TFT) is investigated. As an simple one-pot process without post treatment, inorganic acids (sulfuric acid, phosphoric acid and boric acid) are added into aqueous metal nitrate solution and the subsequent thermal annealing of spun-on film at $350^\circ C$ is conducted. Oxyanions derived from inorganic acid do not undergo thermal decomposition and form robust metal-oxyanion complex. In oxyanion-incorporated IZO thin films, oxyanions turn out to not only reduce oxygen vacancies and hydroxyl residues but also form M-O-S-O-M network. As the amount of inorganic acids increased, the transfer curves shift to the positive direction, caused by effective suppression of charge carrier. The optimized oxyanion incorporated IZO TFTs show improved stability against gate bias and additional thermal stresses.
Secondly, we also report an unique combination of bilayer stucture to utilize conductive $In_2O_3$ nanowire due to abundant carrier electrons. $In_2O_3$ nanowires were fabricated by electrospinning process and $ZrO_2$ films were fabricated by solution-process and both were annealed at $400^circ C$ for 1 hour. The $ZrO_2$ layer coated onto nanowire had a thickness around 35 nm. The excess electrons were controlled by insulating $ZrO_2$ layer coated onto $In_2O_3$ nanwoires beneath the source/drain contact. The $In_2O_3$ naonowire transistor with $ZrO_2$ layer exhibited the enhanced switching property with clear on/off state indicating that the $ZrO_2$ layer contols the conductivity of the channel rather than electrically blocks the current fom the channel. In order to elucidate the underlying mechanism for electrical performance, the characteristics of $In_2O_3 film/ZrO_2$ film bilayer TFT are tested and analyzed based on electronic energy band structure.