IEEE Transactions on Electron Devices | 2019
Reverse-Bias Stress-Induced Electrical Parameters Instability in 4H-SiC JBS Diodes Terminated Nonequidistance FLRs
Abstract
In this article, the breakdown voltage (<inline-formula> <tex-math notation= LaTeX >${V}_{\\text {BR}}$ </tex-math></inline-formula>) 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 <inline-formula> <tex-math notation= LaTeX >${V}_{\\text {BR}}$ </tex-math></inline-formula> gradually increases with increasing stress time, but there is no obvious shift of the forward voltage (<inline-formula> <tex-math notation= LaTeX >${V}_{F}$ </tex-math></inline-formula>). The increment in the magnitude of <inline-formula> <tex-math notation= LaTeX >${V}_{\\text {BR}}$ </tex-math></inline-formula> induced by RBS testing is shown to depend strongly on the degree of applied reverse-bias voltage. The physical mechanism of <inline-formula> <tex-math notation= LaTeX >${V}_{\\text {BR}}$ </tex-math></inline-formula> 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<sub>2</sub> at the FLR terminal area are identified to be the main cause, resulting in the increase of <inline-formula> <tex-math notation= LaTeX >${V}_{\\text {BR}}$ </tex-math></inline-formula>. Besides, a simple model is proposed to explain the behavior of <inline-formula> <tex-math notation= LaTeX >${V}_{\\text {BR}}$ </tex-math></inline-formula> instability.