A Physics-Based Effective Mobility Model for Polycrystalline Silicon Thin Film Transistor Considering Discontinuous Energy Band at Grain Boundaries

Abstract

A physics-based effective mobility model for polycrystalline silicon (poly-Si) thin film transistor (TFT) is developed by considering the discontinuous energy band between grain and grain boundary and Gaussian energy distribution at grain boundary. Three conduction mechanisms, thermionic-emission effect, drift-diffusion effect and tunneling effect, are introduced to describe the mobility. It is found that the physical factors, such as the trapped state distribution at grain boundary, the additional potential barrier, the rate of carriers' thermal velocity to diffusion velocity and the in-grain quality, have a strong influence on the effective mobility of poly-Si TFT and would not be neglected or replaced by some fitting parameters. The proposed model provides an accurate and analytical description for the effective mobility of poly-Si TFT. The calculated results of the proposed model are verified by the experimental data. #