Analysis of threshold voltage shift caused by bias stress in low temperature poly-Si TFTs

The degradation phenomenon of low temperature (/spl les/425/spl deg/C) polycrystalline-silicon thin film transistors (poly-Si TFTs) caused by self-heating has been investigated. In n-channel TFTs, the subthreshold characteristics are significantly and rapidly shifted in the positive direction. This is particularly marked in wide channel TFTs and/or small size TFTs. In order to improve reliability, TFTs with divided channel patterns have also been introduced.