Effect of Temperature and Electric Field on Degradation in Amorphous InGaZnO TFTs Under Positive Gate and Drain Bias Stress

The mechanism of the electrical degradation in amorphous InGaZnO thin-film transistors under a positive gate and drain bias stress is investigated. The stress tests under various combinations of bias and temperature reveal that the negative shift of transfer curves accompanied by a hump is attributed to not an electric field or heating alone, but the simultaneous effect of them. Furthermore, the mitigated degradation under a pulsed stress of a reduced pulse period from 2 s to 0.1 ms and the difference in output characteristics between a dc sweep and a pulsed sweep measurements imply that self-heating with the high field could be the main cause of the degradation rather than hot-carrier effect.