Effects of Oxide Electric Field Stress on the Gate Oxide Reliability of Commercial SiC Power MOSFETs

In this work, the influence of various oxide electric field (Eox) stress conditions on the gate oxide lifetime, gate leakage current, and threshold voltage of 1.2 kV 4H-SiC power planar metal-oxide-semiconductor field-effect transistors (MOSFETs) is investigated. The results suggest that high Eox stress (> 9.4 MV/cm) applied to the gate oxide of commercial SiC power MOSFETs for a certain period degrades the oxide lifetime due to high Fowler-Nordheim (F-N) electron tunneling current followed by hole trapping. Moreover, hole trapping enhances the gate leakage current and reduces the threshold voltage. Therefore, the generation of holes under high electric field conditions should be avoided to ensure the reliability of SiC power MOSFETs.