Improvement of PrIZO Thin Films by O2 Plasma Treatment Combined With Low-Temperature Annealing for Thin-Film Transistors

The amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) are of great interest due to their high mobility, excellent homogeneity, and low processing temperature. With energy conservation and flexible electronics emerging, further reducing post-processing temperatures has become a primary concern. $\text{O}_{{2}}$ plasma treatment has received much attention because it can supply oxygen atoms directly and enhance the performance of AOS thin films at low temperatures. In this study, we provide a combined post-treatment incorporating low-temperature annealing and $\text{O}_{{2}}$ plasma treatment to improve the performance of praseodymium-doped indium zinc oxide (PrIZO) thin films and TFTs. With the increase of $\text{O}_{{2}}$ plasma treatment power, the density of PrIZO thin films first increases and then decreases, reaching a maximum of 6.3 $\text{g}\cdot $ cm $^{-{3}}$ at 40 W. With the increasing $\text{O}_{{2}}$ plasma treatment power, the surface roughness of PrIZO thin films first decreases and then increases, achieving a minimum of 0.49 nm at 40 W. The optimized PrIZO TFT exhibits good electric performance with a $\mu _{\text {sat}}$ of 17.9 cm $^{{2}} \cdot \text{V}^{-{1}} \cdot \text{s}^{-{1}}$ , a subthreshold swing (SS) of 0.40 $\text{V}\cdot $ dec $^{-1}$ , a threshold voltage ( ${V}_{\text {TH}}$ ) of −1.1 V, and an ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio of 7.4 $\times \,\,10^{{7}}$ ultimately. A novel combined posttreatment incorporating low-temperature annealing and $\text{O}_{\mathbf {2}}$ plasma treatment is proposed and proved promising.