Degradation Induced by Forward Synchronized Stress in Poly-Si TFTs and Its Reduction by a Bridged-Grain Structure

In this letter, forward synchronized stress (FSS) is proposed to further simulate the working conditions of switching thin-film transistors (TFTs) in active-matrix displays. The FSS induces tremendous device degradation in polycrystalline (poly-Si) TFTs, which is dominated by a dynamic hot carrier (HC) effect. For the first time, it is found that the dynamic HC effect is dependent on both rising time and falling time. Incorporated with TCAD simulations, the degradation mechanism is tentatively discussed. To alleviate such FSS-induced tremendous degradation, a bridged-grain structure, which can effectively suppress the peak value of lateral electric field by multiple reversed junctions, is applied in the active channel of poly-Si TFTs.