Low-Impurity High-Performance Solution-Processed Metal Oxide Semiconductors via a Facile Redox Reaction

Metal oxide semiconductors realized using solution processes have received a great deal of attention because of their low cost and simple fabrication. One major problem associated with the solution approach is the presence of undesired impurity species introduced by precursor solutions. Here, we investigated the effects of impurities on the electrical properties and device performance of metal oxide semiconductor thin-film transistors. It was found that chlorine residues inhibit the formation of the oxide framework and impede electron transport in a chloride precursor-derived metal oxide. To minimize the impurity concentration and produce high-quality oxide semiconductors, we used perchloric acid to remove excess chlorine species in a facile redox reaction. After the removal of chlorine species, the oxygen lattice concentration increased from 53 to 62%, and the field-effect mobility of indium oxide thin-film transistors was improved by >20-fold. Furthermore, devices treated with perchloric acid showed superior electrical stability under bias stress tests, corresponding to an improved oxide quality.