Degradation Behavior and Mechanism of SiC Power MOSFETs Under Repetitive Transmission Line Pulse Stress

The electrostatic discharge robustness of silicon carbide (SiC) power metal–oxide–semiconductor field-effect transistors (MOSFETs) are investigated by the transmission line pulse (TLP) method. The degradation behavior of key electrical parameters of the device under repetitive TLP stress is investigated. A decrease in threshold voltage, an increase in gate leakage current, and the degradation of gate capacitance parameters are observed compared with the prestress values. Low-frequency noise (LFN) test results show that after multiple TLP stress cycles, the typical leakage current noise of the device increases by approximately one order of magnitude compared to prestress, which means that the trap density extracted based on the McWhorter model increases by one order of magnitude after 1000 TLP stress pulses. Furthermore, sources of defects in the gate oxide dielectric of the devices after stresses are analyzed. The physical mechanism of the changes of SiC MOSFETs characteristics could be attributed to the hole trapping by oxygen vacancy defects and single carbon interstitial in the oxide layer after TLP stresses, which induces an electrostatic effect and results in the changes in the electrical properties of the devices. The results may be useful in the design and application of SiC power MOSFETs.