HIGH-FIELD 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 char acteristics be carefully modelled. However, deviations from the gradua l channel approximation, even at drain voltages below saturation, are observed in polysilicon thin-film transistors (TFTs). This paper inves tigates the effects of nonohmic conduction mechanisms on the output ch aracteristics, and accounts for the excess current through a simple ph ysical model suitable for implementation in a circuit simulator. The m odel is then used to investigate high-field effects in polysilicon TFT s.