Analysis of on-state static and dynamic transients of high voltage 4H-SiC Merged-PiN-Schottky diode

The 4H-SiC vertical Merged-PiN-Schottky (MPS) diodes are attractive power devices with potentials to be used in high-power DC-DC converter with high voltage ratings in the range of 1.7 kV and high operating temperatures, as an alternative to Junction Barrier Schottky (JBS) diodes. This paper reveals the dynamic switching performance and the static characteristics of the SiC MPS diode in comparison with the Silicon PiN diodes and SiC JBS diodes through a wide range of experimental measurements. It shows the superior switching performance of the SiC MPS and JBS diodes due to the absence of the reverse recovery charge. However, it is shown that this is at the cost of the large on state voltage especially at high currents and high temperatures and the increasing forward voltage during the conduction state. As the temperature dependence of forward voltage of Silicon PiN diodes is negative, they are prone to thermal runaway when connected in parallel. Such destructive consequence is also hold for single SiC MPS diode as it is shown that the lack of conductivity modulation leads to a surge of forward voltage in the on-state.