Low-Temperature Chemical Transformations for High-Performance
Solution-Processed Oxide Transistors
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Abstract
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
°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
(In<sub>2</sub>O<sub>3</sub>) and indium zinc oxide (IZO) thin film
transistors with mobility greater than 30 cm<sup>2</sup>/(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)
