4H-SiC PIN二极管的各向异性迁移率效应

Effect of Anisotropic Mobility on Forward DC Characteristics of 4H-SiC PIN Diodes

对制造的单mesa终端4H-SiC PIN二极管,采用数值仿真和测试结果比对的方法,分析了各向异性迁移率效应对4H-SiC PIN二极管正向直流特性的影响。详细阐述了器件的正向直流仿真物理模型和参数选取,其中,迁移率的各向异性关系是在各向同性迁移率模型的基础上引入的,载流子寿命采用空间赋值的方法代入模型进行计算。对比结果显示,采用各向同性迁移率模型的仿真结果与实验值偏差较大,对迁移率模型进行各向异性修正后,仿真结果与实验结果符合得较好。研究表明,实际制造的4H-SiC PIN二极管在直流开态下,存在迁移率的各向异性效应。

The effect of anisotropic mobility on the forward DC characteristics of mesa-terminated 4H-SiC PIN diodes has been studied by comparing the numerical simulation and experimental results. The physical models and relevant characteristic parameters used in the simulation have been described in detail. In particular, the anisotropic mobility has been introduced based on the isotropic mobility model, and the carrier lifetime extracted from the switch-off measurement has been taken directly as spatial lifetime for the numerical calculation. Comparative results show that the simulation using single isotropic mobility model can not achieve quite well agreement with the measured curve, unless adding an anisotropic correction into the mobility model. This indicates that there is an anisotropic mobility of carrier transport when diode operates at ON-state.