Degradation Phenomena of low-temp. poly-Si TFT's Under Electrical Stress Before and After Hydrogenation

The degradation mechanism in hydrogen passivated and as-fabricated poly-Si TFT’s are investigated under the various electrical stress conditions. It is observed that the charge trapping in the gate dielectric is the dominant degradation mechanism in poly-Si TFT’s which was stressed by the gate bias alone while the creation of defects in the poly-Si film is prevalent in gate and drain bias stressed devices. The degradation due to the gate bias stress is dramatically reduced with hydrogenation time while the degradation due to the gate and drain bias stress is increased a little. From the experimental results, it is considered that hydrogenation suppress the charge trapping at gate dielectrics as well as improve the characteristics of poly-Si TFT’s.