Double-stacked gate insulators SiOx/TaOx for flexible amorphous InGaZnO thin film transistors

Abstract

The double-stacked gate insulators (DSGI), which consisted of SiOx (300 nm)/TaOx (300 nm), were used to improve the electrical performance and bias-stress stability of flexible amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). Compared with the devices with single-layer gate insulators (SLGI, 600-nm-thick SiOx), the flexible a-IGZO TFTs with DSGI exhibited not only better electrical performance but also more stable properties during their positive bias-stress (PBS) tests. This was assumed to result from the fact that DSGI had both larger relative dielectric constant and better interface to a-IGZO. Especially, the flexible a-IGZO TFTs with DSGI were more prone to the bending treatment during their PBS tests. This was mostly due to the smaller bending-induced tensional stresses in the devices with DSGI, which arose from the much larger Young's modulus of TaOx films.