Low-Temperature Chemical Transformations for High-Performance Solution-Processed Oxide Transistors

The challenges associated with low-temperature solution-processed metal oxide network formation have hindered the realization of high-performance solution-based electronic circuitry at temperatures lower than 200 degrees C. Here, UV irradiation is embarked upon as a route to effectively transform the chemical precursors to semiconducting metal oxides with high electrical quality. High-performance UV-irradiated indium oxide (In2O3) and indium zinc oxide (IZO) thin film transistors with mobility greater than 30 cm(2)/(V s) have been obtained from nitrate-based precursors. The chemical transformation has been monitored by detailed spectroscopic studies, physical characterization, and temperature-dependent electrical transport measurements. In comparison to thermal annealing, UV annealing seems to result in higher M-O-M network formation (depicted by M-O bonds in XPS), better removal of chemical impurities (depicted by FTIR and XPS), and structural relaxation driven electron doping, transforming the oxygen vacancies to act as shallow donors (depicted by TFT characteristics, XPS, XRD, and Urbach studies). Our results provide new insight into how UV irradiation drives metal oxide network formation and passivates the subgap density of states (DOS).