Avalanche robustness of SiC Schottky diode

Reliability is one of the key issues for the application of Silicon carbide (SiC) diode in high power conversion systems. For instance, in high voltage direct current (HVDC) converters, the devices can be submitted to high voltage transients which yield to avalanche. This paper presents the experimental evaluation of SiC diodes submitted to avalanche, and shows that the energy dissipation in the device can increase quickly and will not be uniformly distributed across the surface of the device. It has been observed that failure occurs at a fairly low energy level (< 0.3 J/cm2), on the edge of the die, where the electrical field intensity is the greatest. The failure results in the collapse of the voltage across the diode (short-circuit failure mode). If a large current is maintained through the diode after its failure, then the damage site is enlarged, masking the initial failure spot, and eventually resulting in a destruction of the device and an open circuit.