Thermal Management of (Ultra) Wide-Bandgap Power Semiconductor Devices

Compared to silicon, Wide and Ultra-Wide BandGap (WBG/UWBG) semiconductor materials allow impressive performance gains for power devices. They can operate at higher voltage and higher switching frequency, and it is often assumed that all of these materials allow for operation at higher power density and higher temperature.In reality, optimal junction temperature and heat flux density depend widely from one material to another and from one device type to another. While it is true that some WBG transistors can operate at high temperature (>200 or even 300°C for SiC JFETs), some others should be maintained at a much lower junction temperature (100°C or less for high-voltage SiC MOSFETs, for example). Some devices benefit from a high-performance cooling system, enabling them to operate at a high heat flux density (up to 1000W/cm² for low-voltage SiC MOSFETs), while some others are best used at the same heat flux density as silicon devices (200W/cm² for GaN HeMTs, for example).In this presentation, I will review the limiting factor for these materials and devices, showing what is the "sweet spot" in terms of thermal management for devices such as SiC MOSFETs, JFETs and diodes, GaN HeMTs, and Ga2O3 diodes. I will highlight the key advantages of WBG and UWBG materials, but also discuss some common misconceptions. Case studies will be presented showing how thermal management systems could be designed to best match the requirements of each device.