Enhanced Electrical Performance and Stability in Zinc Oxynitride Thin-Film Transistors via Sequential Ultraviolet and Thermal Treatment

In this letter, the sequential combination of ultraviolet (UV) irradiation and thermal annealing is proposed as an effective post-deposition treatment method to improve the electrical performance and stability in high-mobility zinc oxynitride (ZnON) thin-film transistors (TFTs). The results indicated that the sequential combination of UV irradiation and thermal annealing at 270°C more effectively increased the field-effect mobility of the TFT and improved the electrical stability of the device under positive gate-bias stresses when compared with other post-deposition treatment methods of UV irradiation, thermal annealing at 270°C, and thermal annealing at 350°C. A decrease in the number of the defective ZnXNY bonds and an increase in that of the stoichiometric Zn3N2bonds were clearly observed when the ZnON thin-film was post-treated by the sequential combination of UV irradiation and thermal annealing at 270°C. A decrease in the defective ZnXNY bond-related subgap states is considered as the dominant mechanism responsible for the enhanced electrical properties of the UV-after thermally treated ZnON TFTs.