Solution-Processed High-k HfO₂ Gate Insulator for High-Performance Indium-Zinc-Oxide Thin-Film Transistors:...

With the continuous advancement of display technology and advanced integrated circuits, oxide thin-film transistors (TFTs) have become core devices due to their high mobility, low leakage current and excellent large-area uniformity. To achieve low power consumption, high performance and high reliability, the introduction of high-k gate insulating layers is crucial. Among the numerous high-k materials, hafnium oxide (HfO₂) has attracted significant attention due to its excellent dielectric properties and good compatibility with CMOS processes. In this paper, uniform and dense HfO₂ films were successfully fabricated using the sol-gel method to serve as insulating layers for TFT devices. Through experimental analysis, 400 °C was determined to be the optimal annealing temperature. At this temperature, the effects of replacing SiO₂ with HfO₂ as the insulating layer, as well as the impact of reducing film thickness, on TFT devices were investigated. Ultimately, at an annealing temperature of 400 °C, an 85 nm-thick HfO₂ film achieved the highest on/off current ratio (I_on/off = 1.11 × 10⁶), the lowest subthreshold swing (SS = 0.53 V/dec), the lowest threshold voltage (Vth = -1.1 V) and the lowest off-current ratio (I_off = 2.5 × 10^-12 A). It was confirmed that replacing SiO₂ with HfO₂ as the insulating layer is a viable approach for reducing the volume of TFT devices.