Degradation in polysilicon thin film transistors related to the quality of the polysilicon material

摘要

Gate bias stress as well as hot-carrier stress are applied to polysilicon thin film transistors made from two types of channel-silicon dioxide interface. The transfer characteristics of the two types of TFTs were measured in the range of temperature from 90K up to 450K. Initially the material constituting the channel region is more defected in one type and TFTs made from this last type degrade more than the other. The degradation is observed from the increase of the substhreshold slope S, the shift of the threshold voltage V_T, and the increase of the defect density in the channel region.