Low-Temperature Fabrication of Indium Oxynitride Thin-Film Transistors via Plasma-Assisted Solution Process

The relatively high thermal annealing (TA) temperature and long TA time during the postprocessing seriously impede the application of solution-processed routes in printable flexible metal oxide (MO) electronic devices. Here, we propose a novel low-temperature solution-processed route, which employs NH ₃ or N ₂ plasma instead of TA to treat preannealing MO thin films, for the fabrication of MO thin films at low temperatures. The results indicate that the NH ₃ or N ₂ "plasma-assisted solution processes" (PASPs) make the preannealing indium oxide (InO _x ) thin films change into indium oxynitride (InON) thin films and effectively reduce the postprocessing temperature and time of InON thin films. The InON thin-film transistor (TFT) based on NH ₃ PASP exhibits acceptable electrical characteristics with a saturation mobility ( $\mu _{\text {sat}}{)}$ of 1.30 cm ² /Vs and an ${I}_{\text {on}}/{I}_{\text {off}}$ of 10 ⁷ at 160 °C; however, there are apparent local plasma-damage regions on the surface of InON thin films. Compared to NH ₃ PASP, the N ₂ PASP shows a better low-temperature activation effect while avoiding plasma damage. The InON TFT based on N ₂ PASP exhibits excellent electrical characteristics with $\mu _{\text {sat}}$ of 5.91 cm ² /Vs and ${I}_{\text {on}}/{I}_{\text {off}}$ of 10 ⁸ at postprocessing temperatures as low as 100 °C and time as short as 33 min. These findings highlight the critical role of plasma treatment (PT) atmospheres in the low-temperature fabrication of the InON thin films via PASP and provide an effective low-temperature solution-processed route to guarantee the development of printable flexible MO electronic devices in the future.