A Physics-Based Approximation for the Polysilicon Thin-Film Transistor Surface Potential

A closed-form approximation for the surface potential of partially depleted polysilicon thin-film transistors with an undoped or lightly doped body is developed by including both monoenergetic midgap and exponential band-tail trap states. The proposed scheme provides a complete modeling for surface potential and is computationally efficient, which is critical in compact modeling and circuit simulator applications. Its high accuracy in predicting the surface potential under various bias and trap density conditions has been verified by a comparison with the numerical results.