Tunable physical properties of Al-doped ZnO thin films by O2 and Ar plasma treatments

Al-doped ZnO (AZO) is a promising transparent conducting oxide that can replace indium tin oxide (ITO) owing to its excellent flexibility and eco-friendly characteristics. However, it is difficult to immediately replace ITO with AZO because of the difference in their physical properties. Here, we study the changes in the physical properties of AZO thin films using Ar and O2 plasma treatments. Ar plasma treatment causes the changes in the surface and physical properties of the AZO thin film. The surface roughness of the AZO thin film decreases, the work function and bandgap slightly increase, and the sheet resistance significantly decreases. In contrast, a large work function change is observed in the AZO thin film treated with O2 plasma; however, the change in other characteristics is not significant. Therefore, the results indicate that post-treatment using plasma can accelerate the development of high-performance transparent devices.