Enhancement of IGZO TFT Performance via Metal-Induced Crystallization: A Pathway to High-Performance Next-Generation Displays

This study demonstrates that IGZO compositions with low-indium (In) content can undergo effective crystallization via a low-temperature route. The IGZO films were initially thermally annealed at 400 °C to enhance structural quality, followed by titanium (Ti) metal-induced crystallization (MIC) at 300 °C under ambient oxygen conditions. Systematically varying the zinc (Zn) content in the IGZO channel while maintaining a fixed indium-to-gallium ratio revealed the relationship between microstructural evolution and electrical performance/stability. The optimized composition, In_0.22Ga_0.17Zn_0.61O, enabled the formation of a highly aligned crystalline phase, resulting in excellent electrical performance in the corresponding thin-film transistors (TFTs), including a field-effect mobility of 73.4 ± 8.9 cm²/V·s, a near-zero threshold voltage (V_TH) of 0.33 ± 0.48 V, and a low subthreshold swing of 174.9 ± 66.8 mV/decade. The devices exhibited consistent electrical characteristics across reproducibility tests on independently fabricated samples and aging tests after storage in ambient air for over three months. In addition, the devices demonstrated excellent operational stability under both positive- and negative-bias temperature stress (ΔV_TH = +0.13 and -0.20 V, respectively) and strong stability under positive- and negative-bias illumination stress (ΔV_TH = +0.23 and -0.28 V, respectively). Under constant current stress, the devices maintained a current retention rate of 98.79%, further confirming their robustness. In contrast, excessive Zn content induced ZnO phase separation, increased trap densities, and deteriorated device characteristics. These results highlight the pivotal role of Zn in governing crystallization behavior and defect control in oxide semiconductors. The MIC strategy employing Ti, an industry-compatible material, offers a scalable, low-temperature route to high-performance IGZO TFTs and a compelling alternative to conventional low-temperature polycrystalline oxide technologies for next-generation active-matrix organic light-emitting diode displays, including information technology, automotive, transparent, and flexible applications.