High-Mobility Crystalline Hexagonal Homologous Compound IZTO Thin-Film Transistors for Next-Generation Active-Matrix Organic Light-Emitting Diode Displays: A Metal-Induced Crystallization Approach

Abstract

While amorphous indium gallium zinc oxide (α-IGZO) thin film transistors (TFTs) are practical alternatives to silicon-based TFTs, their field-effect mobility (∼50 cm2/(V s), depending on deposition conditions) remains insufficient to meet the growing demands of high-resolution active-matrix organic light-emitting diode (AMOLED) displays. The need for high-performance oxide TFTs with mobility ≥100 cm2/(V s) has become critical to meet the evolving display industry’s requirements. This study explored the development of high-mobility hexagonal homologous compound (HC) indium zinc tin oxide (IZTO) TFTs as an alternative to α-IGZO TFTs. A metal-induced crystallization (MIC) technique using tantalum (Ta) was employed to induce crystallization in the IZTO thin films at significantly reduced annealing temperatures, overcoming the fabrication challenges associated with nonuniform capping layer etching. The HC IZTO thin films were optimized with an In/Zn/Sn stoichiometry of 15:75:10 and a thickness of 10 nm. The resulting HC IZTO TFTs exhibited exceptional performance, with a μFE of 110.6 ± 2.4 cm2/(V s), a threshold voltage (VTH) of 0.2 ± 0.3 V, a subthreshold gate swing of 116.8 ± 1.4 mV/dec, and an ION/OFF ratio of 8.2 × 109. Furthermore, the devices exhibited excellent reproducibility, with a VTH standard deviation of ±0.3 V across 30 devices, and outstanding stability under both positive and negative bias temperature stress, with VTH shifts of +0.08 and −0.05 V, respectively, after 3 h at 80 °C. These results set a new benchmark for physical vapor deposition (PVD)-based multicomponent oxide TFTs, highlighting the potential of HC IZTO TFTs for next-generation, high-resolution AMOLED displays with enhanced performance, reliability, and manufacturability.