HfO₂ Gate Dielectric Modulation on Electrical Properties and Stability of IGZTO Thin-Film Transistors

In the fields of display and flexible electronics, indium gallium zinc tin oxide thin-film transistors (IGZTO TFTs) have become core devices promoting the development of next-generation high-resolution displays, transparent circuits and flexible sensing technologies, owing to their high mobility, low leakage current and excellent optical transmittance. High-k gate dielectrics possess outstanding charge modulation capability, which can effectively reduce operating voltage and subthreshold swing of devices, playing a crucial role in improving TFTs performance. In this work, IGZTO TFTs were fabricated by radio frequency magnetron sputtering with SiO₂ and high-k HfO₂ as gate dielectrics, respectively. The results demonstrate that interface engineering and gate voltage modulation between HfO₂ dielectric and IGZTO channel layer remarkably optimize carrier transport behavior, realize low-voltage driving and low subthreshold swing, and greatly enhance electrical characteristics as well as bias stability. Compared with SiO₂/IGZTO TFTs, HfO₂/IGZTO TFTs exhibit superior device performance: the threshold voltage is tuned from −7.34 to 0.35 V, subthreshold swing decreases from 0.827 to 0.096 V/decade, and field-effect mobility increases from 30.3 to 45.8 cm²V⁻¹s⁻¹. Device stability is also significantly improved, with threshold voltage shifts ΔV_th of −0.21 V and −0.11 V under negative bias stress (NBS) and positive bias stress (PBS), respectively. The results indicate that the HfO₂/IGZTO TFTs prepared at room temperature, which combine high mobility and high stability, have broad application prospects in future high-resolution displays and advanced flexible electronics.