Abstract: A new physical current-voltage model for polysilicon thin-film transistors (poly-Si TFTs) is presented.Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function,which greatly improves computational efficiency and is critical in circuit simulation.Based on the exponential density of trap states and the calculated surface potential,the drain current characteristics of the subthreshold and the strong inversion region are predicted.A complete and unique drain current expression,including kink effect,is deduced.The model and the experimental data agree well over a wide range of channel lengths and operational regions.

Key words: polysilicon thin film transistors, surface potential, DC model, kink effect