基于表面势的N沟4H-SiCMOSFETI-V特性解析模型

Analytical Model for the I-V Characteristic of N-channel 4H-SiC MOSFET Based on Surface Poten tial

报道了一种适于模拟 n沟 4H-Si C MOSFET直流 I-V特性的整体模型。该模型充分考虑了常温下 Si C中杂质不完全离化以及界面态电荷在禁带中不均匀分布的影响 ,通过解析求解泊松方程以及牛顿 -拉夫森迭代计算表面势 ,得到了表面电场以及表面势的分布 ,并以此为基础采用薄层电荷近似 ,计入栅压引起的载流子迁移率退化效应 ,导出了可用于所有器件工作区的统一漏电流解析表达式。当漏偏压为 1 0 V,栅压为 1 2 V时 ,模拟得到的饱和漏电流接近 40 m A。计算结果与实验值符合较好。

An improved physi cal-based analytical model which can be used in all the operation regions for th e dc I-V characteristic of n-channel 4 H- SiC MOSFET is reported. The electric fie ld at the semiconductor surface is obtai ned by an analytical solution of the Poi sson equation and iterative calculation of the surface potential firstly, and th en the analytical expression for drain c u rrent is developed based on charge-sheet simplification. The influences of incom plete dopant ionization and the non-unif orm distribution of interface state char ge are considered simultaneously. The saturation drain current of nearly 40 mA is obtained at a gate voltage of 12 V as drain voltage is 10 V. The co mparison between simulations and physica l measurements shows a good agreement.