Effects of Nitrogen and Hydrogen Codoping on the Electrical Performance and Reliability of InGaZnO Thin-Film Transistors

Abstract

Despite intensive research on improvement in electrical performances of ZnO-based thin-film transistors (TFTs), the instability issues have limited their applications for complementary electronics. Herein, we have investigated the effect of nitrogen and hydrogen (N/H) codoping on the electrical performance and reliability of amorphous InGaZnO (α-IGZO) TFTs. The performance and bias stress stability of α-IGZO device were simultaneously improved by N/H plasma treatment with a high field-effect mobility of 45.3 cm²/(V s) and small shifts of threshold voltage (V_th). On the basis of X-ray photoelectron spectroscopy analysis, the improved electrical performances of α-IGZO TFT should be attributed to the appropriate amount of N/H codoping, which could not only control the V_th and carrier concentration efficiently, but also passivate the defects such as oxygen vacancy due to the formation of stable Zn-N and N-H bonds. Meanwhile, low-frequency noise analysis indicates that the average trap density near the α-IGZO/SiO₂ interface is reduced by the nitrogen and hydrogen plasma treatment. This method could provide a step toward the development of α-IGZO TFTs for potential applications in next-generation high-definition optoelectronic displays.