Effects of Atomic-Layer-Deposition Temperature on the Properties of Al2O3 Insulators and InAlZnO Thin-Film-Transistors with Dual-Active-Layer Structure

Abstract The influence of atomic layer deposition (ALD) temperature on the properties of Al2O3 gate insulators and InAlZnO (IAZO) thin film transistors (TFTs) with a dual-active-layer structure was systematically investigated. The 150℃-prepared Al2O3 film had the best surface morphology as well as capacitance and breakdown characteristics, and the corresponding IAZO TFT also showed the optimal overall performance with a high saturation mobility (11.39 cm2 V-1 s-1), a low threshold voltage (0.32 V), a small subthreshold swing (0.13 V dec-1) and an ideal on-off current ratio (1.25×108). The IAZO TFTs using 150℃-deposited Al2O3 insulator also exhibited excellent illumination reliability and good positive bias stress (PBS) stability. In particular, the band offsets between Al2O3 and IAZO were investigated to better understand the PBS mechanism of our IAZO TFTs.