30.3: Impact of Top Gate Insulator Deposition Temperature on Electrical Performance of Dual‐Gate a‐InZnO TFTs

Abstract

The electrical characteristics and stability of dual‐gate amorphous InZnO thin film transistors (a‐IZO TFTs) with top gate insulators (TGIs) deposited under different conditions were investigated. It is found that the TFT with 150°C SiO2 as TGI has higher mobility, while TFT with 300°C SiO2 as TGI has lower off‐state leakage current and better stability under bias stress. Experimental results show that the TFT with stacked TGI deposited at 150°C first and then 300°C can combine the merit of the 150°C SiO2 and 300°C SiO2, achieving high saturation mobility (23.9 cm2/V·s), low off‐state leakage current (10‐14 ~10‐12 A) and also good stability under negative bias stress (NBS) and positive bias stress (PBS) of 3600 s @30 V, with only negative drift of 0.02 V and 0.15 V, respectively. Moreover, it also performs well under negative bias temperature illumination stress (NBTIS) and positive bias temperature illumination stress (PBTIS).