(Invited) Thermal Limitations in Wide Bandgap (WBG) Semiconductor Power Switching Devices

Power switching devices made using wide bandgap (WBG) semiconductors such as Silicon Carbide (SiC) and Gallium Nitride (GaN) have the potential to make transformative impact on electrical energy generation, transmission, distribution and conditioning [1]. Although SiC power diodes and power MOSFETs are commercially available for voltage ratings up to 1,700 volts, a careful review of the published data suggests that reliability of WBG power devices may be severely compromised compared to identically rated silicon power devices. For example, dv/dt, avalanche, and safe-operating area (SOA) of SiC power diodes and MOSFETs are inferior to silicon power devices with identical ratings. This paper will present a simple physics-based thermal analysis of the power handling capability of WBG power devices and explain the possible causes of lower reliability ratings.

[1] K. Shenai et al, “Current status and emerging trends in wide bandgap (WBG) semiconductor power devices,” ECS J. Solid State Sci. and Tech. 2(8), N3055-N3063, Jul. 2013.