Gate Switching Instability in Silicon Carbide MOSFETs—Part I: Experimental

Abstract

In the context of renewable energy generation, compact and efficient electric power conversion is becoming increasingly important. Due to their low-loss switching capability at high frequencies, of up to hundreds of kilohertz, silicon carbide (SiC) MOSFETs are currently gaining a lot of attention from industry and are gradually replacing silicon (Si)-based devices in numerous applications. Recently, it has been revealed that SiC MOSFETs show a new type of instability in extensive high-frequency operations when the device is switched in bipolar mode. This gate switching instability has been observed in all commercial devices and occurs concurrently with the well-known bias temperature instability. We summarize the defining experimental characteristics of gate switching instability, including frequency, voltage, temperature, transition time dependencies, and the impact of undershoots in gate voltage. Subsequently, we discuss these observations together with those from other researchers, including recently proposed mechanisms and how they agree or disagree with the available experimental evidence. In the second part of this publication, we will present a detailed physics-based model that fully agrees with all presented experiments.