The degradation mechanisms of both negative bias temperature instability ͑NBTI͒ and positive bias temperature instability ͑PBTI͒ were studied for low-temperature polycrystalline silicon complementary thin-film transistors. Measurements show that both NBTI and PBTI are highly bias dependent; however, the effect of the temperature is only functional on the NBTI stress. Furthermore, instead of interfacial trap-state generation during the NBTI stress, the PBTI stress passivates the interface trap

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... ates. We conclude that the diffusion-controlled electrochemical reactions dominate the NBTI degradation while charge trapping in the gate dielectric controls the PBTI degradation.