Gate Voltage Pulse Rising Edge Dependent Dynamic Hot Carrier Degradation in Poly-Si Thin-Film Transistors

Dynamic degradation becomes a critical issue for thin-film transistors (TFTs) used in emerging new displays driven by high frequency gate voltage {V}_{\text {G}} pulses. In this study, {V}_{\text {G}} pulse rising edge dependent dynamic hot carrier degradation of poly-Si TFTs is investigated. It is demonstrated that rising edge of {V}_{\text {G}} pulses which swing within the OFF-state of TFTs causes the degradation, while that of normal {V}_{\text {G}} pulses which switch between the ON and OFF states across the flat band voltage {V}_{\text {FB}} of TFTs does not. Based on transient TCAD simulation, the underlying mechanism of rising edge dependent degradation is proposed, which is based on the non-equilibrium PN junction degradation model previously proposed to explain {V}_{\text {G}} pulse falling edge dependent degradation of poly-Si TFTs. Hence, the dynamic degradation model of poly-Si TFTs related to both rising and falling edge of the {V}_{\text {G}} pulses can be unified now, which is applicable to fast gate pulses with steep rising and/or falling edges in sub- \mu \text{s} level.