Improvement in negative-bias-illumination-stress stability of fully-transparent double-gate a-IGZO thin-film transistors

Fully-transparent amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) with double-gate (DG) configuration were demonstrated. Each top-gate (TG) and bottom-gate (BG) TFT fabricated with single gate-stack structure was found to exhibit sound device characteristics. The benefits of DG configuration, such as improved current drivability and threshold voltage tunability, were also well confirmed. It was noticeable that the device stability under the negative-bias-illumination-stress (NBIS) conditions could be successfully enhanced by controlling the fixed voltage bias applied to the B G. From these results, it was suggested that the NBIS instabilities at blue wavelength were dominantly caused by the hole trapping mechanism.