A Figure of Merit for Power FET Switching Devices

SiC MOSFETs are now widely accepted as replacement parts for IGBTs. In contrast, however, the presumption is that a GaN HEMT devices should be used with a higher switching frequency, as their use tends to suggest a reduction in size of the overall equipment. To understand what advantages might be possible, in this paper we present the characteristics of WBG devices as they are currently available, compare their switching results to Si devices and propose a new Figure of Merit that can be used to compare devices in a way that gives insight into their actual switching performance and what can be easily achieved practically.