Analysis of Effects of Defects on Degradation Mechanism of 1200-V/40-A 4H-SiC Junction Barrier Schottky Diodes Induced by High-Reserve Bias Stress

The influence of morphological defects on long-term reliability of 1200-V/40-A 4H-SiC junction barrier Schottky (JBS) diodes under the 668 h of reverse bias stress (RBS) is investigated in depth. The variation of electrical properties and related degradation mechanisms is analyzed. It is found that the breakdown voltage ( <tex-math notation="LaTeX">VBR</tex-math> ) increment of the samples containing morphological defects is significantly larger than that of samples without defects after RBS. Moreover, the specific on-resistance ( <tex-math notation="LaTeX">Rₛₚ</tex-math> ) of the former increases with the increase in stress time due to the increase in ideal factor ( n ) and the decrease in barrier height (2.). The C – V characteristics and simulation results demonstrate that the hole injection in the SiO <tex-math notation="LaTeX">₂</tex-math> /SiC interface of edge termination could be responsible for the observed variation of <tex-math notation="LaTeX">VBR</tex-math> after RBS. In addition, further analysis indicate that the trap energy levels related to the morphological defects contribute to the process of trapping carriers at the interface, and the degradation mechanism of the forward and reverse characteristics of 4H-SiC JBS under RBS is revealed by the energy band model.