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

Abstract

In this article, the breakdown voltage ( ${V}_{\text {BR}}$ ) 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 ${V}_{\text {BR}}$ gradually increases with increasing stress time, but there is no obvious shift of the forward voltage ( ${V}_{F}$ ). The increment in the magnitude of ${V}_{\text {BR}}$ induced by RBS testing is shown to depend strongly on the degree of applied reverse-bias voltage. The physical mechanism of ${V}_{\text {BR}}$ 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 SiO2 at the FLR terminal area are identified to be the main cause, resulting in the increase of ${V}_{\text {BR}}$ . Besides, a simple model is proposed to explain the behavior of ${V}_{\text {BR}}$ instability.