Self-Heating Effect on Bias-Stressed Reliability for Low-Temperature a-Si:H TFT on Flexible Substrate

Hydrogenated amorphous silicon thin-film transistors on colorless polyimide substrates were successfully fabricated at a low process temperature (160°C). The gate leakage current is as low as 10^-13 A, while the field-effect mobility is 0.42 cm²V^-1 · s^-1, and the subthreshold swing is 0.77 V/dec. Using bias-temperature stress on devices with different channel widths, the enhancement of self-heating effect on bias-stressed reliability is investigated for the first time. Elevated temperature due to self-heating effect is estimated either by extending the bias-stressed model or by modifying the thermal equivalent circuit model. Degradation of device reliability on a bent substrate is also significant when self-heating effect is incorporated.