6H-和4H-SiC功率VDMOS的比较与分析

采用二维器件模拟器ISE TCAD 7.0,对比研究了6H-SiC和4H-SiC VDMOS的基本特性.结果表明,在Vgs为8 V时,4H-SiC VDMOS的漏极电流比6H-SiC高约1.5倍,证实了4H-SiC具有较高的体迁移率,且受准饱和效应的影响较小,因此比6H-SiC器件具有更高的饱和电流密度,而两种器件的阈值电压基本相同,均为7 V左右.对器件开关时间和单位面积损耗的分析表明,4H-SiC比6H-SiC更适合用于VDMOS功率器件.此外,还研究了沟道长度对器件漏极饱和电流的影响,结果表明,随着沟道长度的减小,器件的漏极电流增大.

Comparison and Analysis Between 6H-and 4H-SiC Power VDMOSFETs

The basic characteristics of 6H-and 4H-SiC VDMOSFETs were compared and investigated by 2D device simulator ISE TCAD 7.0, and the results show that the drain current of 4H-SiC VDMOSFETs was 1.5 times higher than that of 6H-SiC VDMOSFETs, when Vgs was 8 V. It validates that 4H-SiC devices have much higher saturation current density than 6H-SiC devices, as it has higher body mobility and the effect of quasi-saturation on it was small. Both devices has almost the same threshold voltage of about 7 V. Analysis of the switching time and switching loss per unit area of devices indicates that 4H-SiC is more suitable for use in power VDMOSFETs devices. The effect of channel length on the drain current of devices was studied, and results show that the drain current increases with decrease in channel length.