Dynamic Response of a-InGaZnO and Amorphous Silicon Thin-Film Transistors for Ultra-High Definition Active-Matrix Liquid Crystal Displays
- Resource Type
- Periodical
- Authors
- Yu, E. K.-H.; Zhang, R.; Bie, L.; Kuo, A.; Kanicki, J.
- Source
- Journal of Display Technology J. Display Technol. Display Technology, Journal of. 11(5):471-479 May, 2015
- Subject
- Photonics and Electrooptics
Thin film transistors
Logic gates
Capacitance
Electrodes
Capacitors
Amorphous silicon
Active-matrix
a-IGZO
AM-LCD
amorphous silicon
dynamic response
falling edge
feedthrough voltage
flat-panel displays
overdrive
thin-film transistors (TFTs)
ultra-high definition
- Language
- ISSN
- 1551-319X
1558-9323
The dynamic response of hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) and amorphous In-Ga-Zn-O (a-IGZO) TFT are compared. We study the storage capacitor $(C_{\rm st})$ 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 TFT is insufficient for UHD AM-LCDs and that the a-IGZO TFT is capable of supporting at least 8 K$\times$ 4 K display resolution at 480 Hz. The impact of $C_{\rm st}$ and gate voltage falling edge $(t_{\rm FE})$ on feedthrough voltage $(\Delta V_{\rm P})$ is investigated. Because of higher mobility of the a-IGZO TFT, it is possible to reduce $\Delta V_{\rm P}$ by mitigating channel charge redistribution with non-abrupt $t_{\rm FE}$. The a-IGZO TFT shows no drawbacks in terms of $\Delta V_{\rm P}$ when compared to the a-Si:H TFT. In addition, a larger $C_{\rm st}$ can be used in combination with the a-IGZO TFT to reduce $\Delta V_{\rm P}$ with minimal impact on its charging behavior. Gate overdrive operation is also evaluated for the a-IGZO TFT, which may improve charging characteristics with no adverse effects on $\Delta V_{\rm P}$. Our results show that the a-IGZO TFT is a suitable technology for UHD high-frame rate AM-LCDs.