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.