Potential of GaN vertical JFETs presented through a comprehensive discussion of dynamic performance compared to SiC JFETs

Abstract

In this paper, a comparative study on the switching characteristics and power losses in GaN and SiC vertical junction field effect transistors (VJFETs) is presented. Models of VJFETs based on GaN and SiC, were separately built in Sivaco ATLAS and applied to a mixedmode device/circuit simulator for dynamic evaluation under identical test conditions. The device figure of merit (RonQg) of GaN VJFET is 57% of that for SiC VJFET, showing significantly lower power loss. The switching loss of the GaN VJFET was found to be half that of the SiC device at 100 kHz. From the material point of view, GaN has similar breakdown electric field with SiC, however, the electron mobility in bulk GaN has been experimentally proven to be higher [1] than that in SiC. High mobility enables GaN devices to be operated at high frequency with remarkably lower switching loss.