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 NH3 or N2 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 NH3 or N2 'plasma-assisted solution processes' (PASPs) make the preannealing indium oxide (InOx) 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 NH3 PASP exhibits acceptable electrical characteristics with a saturation mobility (μsat) of 1.30 cm2/Vs and an Ion/Ioff of 107 at 160 °C; however, there are apparent local plasma-damage regions on the surface of InON thin films. Compared to NH3 PASP, the N2 PASP shows a better low-temperature activation effect while avoiding plasma damage. The InON TFT based on N2 PASP exhibits excellent electrical characteristics with μsat of 5.91 cm2/Vs and Ion/Ioff of 108 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.