Surface potential calculation and drain current model for junctionless double-gate polysilicon TFTs

Abstract

Surface potential is a key parameter in evaluating the DC property of thin-film transistors (TFTs). In this paper, for the junctionless symmetric double-gate polysilicon TFTs, a physical-based explicit calculation to surface potential has been derived. Incorporating impurity concentration, mobile charge and trap density into Poisson's equation, a closed form of band bending as a function of gate voltage is obtained and demonstrated as an accurate and computationally efficient solution. Based on surface potential, a drain current model for long-channel devices is provided in explicit forms. Furthermore, it is verified successfully by comparisons with both 2D numerical simulation and experimental data in different operation regions.