Improved performance of solution-processed a-InGaZnO thin-film transistors due to Ar/O₂ mixed-plasma treatment

We investigated the effects of Ar and O₂ treatment and of Ar/O₂ mixedplasma treatment on the electrical characteristics of solution-processed amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs). The electrical performance and the instability of a-IGZO TFTs were significantly improved by the plasma treatments. The plasma treatments reduced the carbon-based residual contamination that acted as possible trap sites. In particular, the O₂-plasma treatment produced a significant improvement in the reliability of a-IGZO TFTs when compared with the Ar-plasma-treated device, owing to the elimination of residual carbon in the active channel of the solution-processed a-IGZO. However, the optimized improvement of the solution-processed a-IGZO TFT under a gate bias stress was obtained for the device treated with an Ar/O₂ mixed-gas plasma. The plasma treatment in the Ar/O₂-mixed ambience remarkably enhanced not only the reliability but also the electrical performance of the a-IGZO TFT; the on/off-current ratio, the field-effect mobility, and the subthreshold slope were 6.78 × 10⁷, 1.24 cm²/V·s, and 513 mV/dec, respectively.