Thermal Requirements of SiC Power Devices
Résumé
Silicon Carbide (SiC) is a very promising material for power devices, for various reasons. In particular, it can operate at very high junction temperature (several hundreds of degrees more than with silicon). As a consequence, it should be possible to reduce the cooling system of a SiC power device compared to its Si counterpart. This would result in a device operating at high junction temperature (relative to the ambient), with a compact thermal management system. However, I will show that depending on the device type (unipolar of bipolar), instabilities can exist : For example, in the case of a unipolar schottky) diode, the conduction losses increase with the junction temperature, and the increase is non-linear. For a given current and thermal resistance of the cooling system, there is a maximum junction temperature above which the device becomes unstable. This means that above this point, the dissipated power increases more quickly than the cooling performance of the thermal system. In the presentation, we will give some experimental results, which we will use to present a very simple model of the phenomenon. This model will be used to show that for some SiC power devices, an despite their high-temperature capability, an efficient thermal management system is mandatory.