Advanced HF SiC MOS devices

The characteristics of silicon carbide, 1200 V, 20 A MOSFETs have been described from a user´s perspective. DC and dynamic characteristics of SiC MOSFETs have been compared with Si 900 V super junction MOSFET (SJMOSFET), Si 1200 V MOSFET and IGBTs. The advantages of SiC MOSFET are their lower turn-off losses, lower conduction losses and lower gate charge. However, they have low output impedance, low transconductance and low threshold voltage. These factors should be taken into account when designing the gate drive and fault detection circuits. The use of the internal body diode is not recommended for SiC MOSFETs due to its high voltage drop and therefore considerations for choosing the rating of external SiC Schottky diode have been presented. The absence of turn-off current tail results in voltage overshoot and ringing and therefore careful minimization of parasitics in the gate drive and load circuits is required. Finally, the results of reliability tests on SiC MOSFETs have been summarized.