High fields effects in polysilicon thin film transistors

Since the performance of both analogue and digital circuits is heavily dependent on device output resistances, accurate simulation of these circuits requires that the saturation regime of the device output characteristics be carefully modelled. However, deviations from the gradual channel approximation, even at drain voltages below saturation, are observed in polysilicon thin-film transistors (TFTs). This paper investigates the effects of nonohmic conduction mechanisms on the output characteristics, and accounts for the excess current through a simple physical model suitable for implementation in a circuit simulator. The model is then used to investigate high-field effects in polysilicon TFTs.