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本文利用薄层电荷理论,建立了一个基于表面势的、物理的多晶硅薄膜晶体管(Polysilicon Thin-Film Transistors ,poly-Si TFTs)的电流模型,且该模型适用于电路仿真。推导了poly-Si TFTs表面势的近似解法,该求解法非迭代的计算大大地提高了计算效率,且精确度高并得到实验验证。基于物理的迁移率方程考虑了晶界势垒高度,和由于声子散射与表面粗糙散射引起的迁移率退化。基于Brews的薄层电荷模型和上述非迭代计算表面势,本电流模型同时考虑了漏致势垒降低(DIBL)效应、kink效应和沟道长度调制效应。对不同沟长的器件实验数据比较发现,提出的模型在很广的工作电压内与实验数据符合得非常好。同时本模型的所有方程都具有解析形式,电流方程光滑连续,适用于电路仿真器如SPICE。
In this paper, a current model based on surface potential and physical properties of poly-Si TFTs is established by using the TLC theory. The model is suitable for circuit simulation. The approximate solution of the surface potential of poly-Si TFTs is deduced. The non-iterative calculation of the solution greatly improves the computational efficiency and is highly accurate and validated experimentally. The physics-based mobility equation takes into account the barrier height of the grain boundary and mobility degradation due to phonon scattering and surface roughness scattering. Based on the Brews-based thin-layer charge model and the above non-iterative calculation of surface potential, the current model considers both the Leakage barrier reduction (DIBL) effect, the kink effect, and the channel length modulation effect. Comparison of experimental data of different device lengths shows that the proposed model is in good agreement with the experimental data over a wide operating voltage range. At the same time, all the equations in this model have the analytical form. The current equation is smooth and continuous, which is suitable for circuit simulator such as SPICE.