Comparison of Dynamic Gate Stress Test Results of SiC MOSFETs

Abstract:
Silicon MOSFETs are continuously replaced by silicon carbide MOSFETs in several applications such as automotive, railway, or renewables. While utilizing the advantages of silicon carbide, such as higher junction temperatures, switching speeds, or efficiency, reliability must be equal or better. Switching a silicon carbide MOSFET using a bipolar gate-source voltage causes drift of the gate-source threshold voltage and the drain-source on resistance. This paper describes the setup used for dynamic gate stress tests of discrete silicon carbide MOSFETs of five manufacturers. It aims to show whether a static voltage below minimum gate-source voltage, an undershoot, or the difference between gate-source on and off state voltage affect the gate-source threshold voltage drift. Therefore, gate switching waveforms as well as observed drift are provided and compared.