Analysis of Degradation Mechanism in Polycrystalline Silicon Thin-Film Transistors under Dynamic Off-State Stress with Fast Transition Time

Abstract This study represents the investigation into the degradation of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) under dynamic off-state stress, with a focus on transition times as rapid as 1 nanosecond (ns). The study found that dynamic off-state stress with larger amplitude leads to more severe device degradation. Unlike previous studies, both the rising time ( t r ) and falling time ( t f ) of the pulse significantly influence the hot carrier (HC) degradation in the poly-Si TFTs. The on-state current degradation rate (Δ I on ) after 10 4 s stress dramatically increases from 11.8% to 80.8% when t r decreases from 500 ns to 1 ns. When t f decreases from 500 ns to 1 ns, Δ I on also dramatically increases from 22.9% to 69.2%. Combined with transient simulations, the source of the carrier for HC degradation is clarified and consequently, a non-equilibrium PN junction degradation model modulated by accumulated electrons is developed.