Modified threshold voltage shift model in a-Si:H TFTs under prolonged gate pulse stress

The threshold voltage (V(T)) instability of hydrogenated amorphous silicon thin film transistor under constant gate bias stress has been examined and modeled as a stretched-exponential equation previously. However, the V(T) shift (Delta V(T)) characteristic under prolonged gate pulsed stress, which also occurs in practical circuit operation, has not been well modeled so far. In this letter, we compared the V(T) shift property with existing models under gate pulse stress. For Delta V(T) under prolonged stress, we found inaccuracies in the previous models and subsequently proposed a modified model, which can be applied to estimate V(T) shift correctly for prolonged pulse stress of various duty ratios.