Reverse-Bias Stress-Induced Electrical Parameters Instability in 4H-SiC JBS Diodes Terminated Nonequidistance FLRs

In this article, the breakdown voltage (V-BR) shift of 4H-SiC JunctionBarrier Schottky (JBS) diodes terminated by optimum nonequidistant field limiting rings (FLRs) subject to reverse-bias stress (RBS) has been investigated, and the corresponding mechanisms are studied in-depth. It can be observed that VBR gradually increases with increasing stress time, but there is no obvious shift of the forward voltage (V-F). The increment in the magnitude of VBR induced by RBS testing is shown to depend strongly on the degree of applied reverse-bias voltage. The physical mechanism of V-BR shifthas been investigatedand explained by means of numerical technical computer-aided design (T-CAD) simulations. Our analysis shows that the hole injection and trapping into SiO2 at the FLR terminal area are identified to be the main cause, resulting in the increase of VBR. Besides, a simple model is proposed to explain the behavior of VBR instability.