4H-SiC基MPS二极管迅回效应分析

Analysis of snapback effect of 4H-SiC based MPS diode

为优化二极管抗浪涌电流能力及正向特性,针对器件工艺参数对迅回效应的影响进行了研究。采用建模仿真对比不同参数下的器件正向特性,分别对P+区和漂移区的掺杂浓度以及P+区宽度3个方面进行讨论。提取在迅回效应过程中器件的正向偏置处于转折与折回电压时漂移区内空穴的分布,进而细化研究该效应的产生过程机理。仿真结果表明,增加P+区的掺杂浓度与宽度可以有效抑制迅回效应,较高的漂移区掺杂浓度会增加器件在单极工作模式下的电流密度,但同时增大转折电压可使迅回效应加剧,适当减小漂移区掺杂浓度可以抑制迅回效应。

In order to optimize the surge current resistance ability and the forward characteristics of diodes,the effect of device process parameters on snapback effect was investigated.A method for modeling and simulation was used to compare the forward characteristics of the devices with different parameters,and three aspects including the doping concentration in P+region,the doping concentration in drift regions and the P+region width were discussed respectively.In addition,the distribution of holes in drift region when the device forward bias was located at the turning and returning voltage under the snapback effect was extracted to elaborately study the generation mechanism of this effect.The results show that increasing the doping concentration and the P+region width can effectively suppress the snapback effect,and higher doping concentration in the drift region will not only increase the current density of the device in unipolar operation mode,but also increase the turning voltage to aggravate the snapback effect.The doping concentration in drift region can be reduced appropriately to suppress the snapback effect.