基于晶界离散分布的多晶硅薄膜晶体管直流模型

Direct Current Model of Polysilicon Thin Film Transistor Based on Discrete Grain Boundary Distribution

基于表面势的多晶硅薄膜晶体管(poly-Si TFT)漏电流模型无法体现晶界的离散分布特性,而基于阈值电压模型的各工作分区电流表达式存在不连续性.为克服此缺点,根据基于表面势模型的建模思想,考虑晶界势垒在沟道中离散分布的特点,提出了多晶硅薄膜晶体管的直流漏电流模型.该模型采用单一的解析方程描述多晶硅TFT各工作区的电流.研究结果表明:TFT工作于线性区且栅压一定时,随着漏压的增大,沟道有效迁移率降低;随着栅压的增大或沟道的缩短,漏电压对沟道有效迁移率的影响减弱.

The drain current model of the polysilicon thin film transistor（poly-Si TFT） based on surface potential can not accurately describe the discrete grain boundary distribution,while the threshold-voltage-based model is not capable of continuously representing the drain currents in different operation regions.In order to solve these pro-blems,a direct drain current model of the poly-Si TFT considering the discrete distribution of grain boundary potential in drains is established based on the surface potential.The proposed model describes the drain currents of the poly-Si TFT in different operating regions via an analytic equation.Simulated results indicate that,when the poly-Si TFT works in the linear region at a certain gate bias,its effective mobility decreases with the increase in drain voltage,and that,with the increase in gate bias or with the decrease in channel length,the effect of drain voltage on the effective mobility weakens.