Effect of temperature and illumination on the instability of a-Si:H thin-film transistors under AC gate bias stress

This work investigates the temperature and illumination effects on the a-Si:H thin-film transistors (a-Sill TFTs) under AC gate bias stress to find the larger threshold voltage shift and subthreshold swing change for the bias-temperature-stress (BTS) and bias-illumination-stress (BIS). Excess carriers from thermal-generation electron-hole pairs or photoexcited electron-hole pairs may significantly influence the instability of a-Si:H TFTs during bias stress. The instability mechanisms originate from the carrier-induced defect creation enhanced by thermal generation in the BTS case and also emphasized by photoexcitation for the BIS case. Both stress conditions will induce a larger threshold voltage shift and higher cutoff frequency than those for simple bias stresses.