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 Junction Barrier 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 V
_BR
gradually increases with increasing stress time, but there is no obvious shift of the forward voltage (V
_F
). The increment in the magnitude of V
_BR
induced by RBS testing is shown to depend strongly on the degree of applied reverse-bias voltage. The physical mechanism of V
_BR
shift has been investigated and explained by means of numerical technical computer-aided design (T-CAD) simulations. Our analysis shows that the hole injection and trapping into SiO
₂
at the FLR terminal area are identified to be the main cause, resulting in the increase of V
_BR
. Besides, a simple model is proposed to explain the behavior of V
_BR
instability.