Low-temperature, solution-processed indium-oxide thin-film transistors fabricated by using an ultraviolet-ozone treatment

For the fabrication of low-temperature solution-processed metal-oxide thin-film transistors (TFTs), alternative annealing processes have recently been studied for reduced fabrication cost and applications to flexible devices. Indium nitrate solution has been proposed as a precursor for the low-temperature solution-processed TFTs. However, due to its high decomposition temperature, achieving a high-performance indium-oxide (In 2 O 3 ) TFT at temperatures below 200°C is still difficult. In this study, for improved metal-oxide formation in low-temperature solution-processed In 2 O 3 TFT, indium nitrate film was exposed to UV-ozone for 30 min before annealing at 200°C. The smooth scanning electron microscopy (SEM) image of the UV-ozone treated film implies that the indium nitrates are condensed after treatment. In addition, X-ray photoemission spectroscopy (XPS) data suggest that UV-ozone decreases the number of oxygen vacancies and increases the number of metal-oxygen-metal bonds in the indium-oxide films. As a result, high electrical device performance was achieved with an improved Ion/off ratio (∼10 7 ) and mobility (1.25 cm 2 V −1 s −1 ).