Synergistic Fluorine and Zirconium Codoping for High-Mobility and Bias-Stable ZnO Thin-Film Transistors

Oxide semiconductors have attracted considerable attention for next-generation electronic applications because of their desirable optoelectronic properties. However, achieving both high performance and long-term stability in zinc oxide (ZnO)-based thin-film transistors (TFTs) is a key challenge. Herein, this issue was addressed using spray-coated ZnO TFTs with fluorine (F) and zirconium (Zr) codoping. The ZnO TFT with 5% Zr doping and a F treatment for 10 s exhibited a high saturation mobility of 31.65 cm²/V·s and a low subthreshold swing of 0.157 V/dec. The codoped TFT showed a superior bias stability (ΔV_TH = ∼0.1 V) under positive bias temperature stress compared to the undoped counterpart (ΔV_TH = ∼0.7 V). These results were attributed to synergistic Zr and F doping, where Zr passivates defects and F increases the free electron concentration. Therefore, F and Zr codoping can be a useful technique to produce more reliable and high-performance solution-processed oxide TFTs.