Dynamic Response of a-InGaZnO and Amorphous Silicon Thin-Film Transistors for Ultra-High Definition Active-Matrix Liquid Crystal Displays

The dynamic response of hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) and amorphous In-Ga-Zn-O (a-IGZO) T_FT are compared. We study the storage capacitor (Cst) charging characteristics by applying gate and data voltage waveforms corresponding to ultra-high definition (UHD) active-matrix liquid crystal displays (AM-LCDs). We show that the charging behavior of the a-Si:H T_FT is insufficient for UHD AM-LCDs and that the a-IGZO T_FT is capable of supporting at least 8 K ×4 K display resolution at 480 Hz. The impact of C_st and gate voltage falling edge (t_FE) on feedthrough voltage (ΔV_P) is investigated. Because of higher mobility of the a-IGZO T_FT, it is possible to reduce ΔV_P by mitigating channel charge redistribution with non-abrupt tFE. The a-IGZO TFT shows no drawbacks in terms of ΔV_P when compared to the a-Si:H T_FT. In addition, a larger C_st can be used in combination with the a-IGZO T_FT to reduce ΔV_P with minimal impact on its charging behavior. Gate overdrive operation is also evaluated for the a-IGZO T_FT, which may improve charging characteristics with no adverse effects on ΔV_P. Our results show that the a-IGZO T_FT is a suitable technology for UHD high-frame rate AM-LCDs.