Experimental Comparison of SiC MOSFET and BJT

Abstract

While silicon carbide (SiC) MOSFET is more popular for medium-voltage power semiconductor devices today, the SiC BJT is still an attractive candidate for high-power, high-frequency and high-temperature power electronics applications because of its several unique advantages such as lower specific on-resistance and higher operation temperature. To know the exact performance difference between SiC MOSFET and SiC BJT, in this paper, a comprehensive comparison between SiC MOSFET and SiC BJT with same voltage and current rating was experimentally investigated under different conditions. At first, we measured all parts of power losses consumed on the power devices in different input voltages, load currents, and operation temperatures. The power losses analysis results show that even though the SiC BJT has smaller turn-off loss and conduction loss than its SiC MOSFET counterpart, the larger turn-on loss and driver loss still make the overall power losses a little larger than SiC MOSFET. Then based on the power losses analysis, we evaluated their maximum power handling capability by comparing the conduction current in a 100kHz fixed input voltage DC/DC boost converter with same temperature margin taken into account. It is experimentally verified that the SiC BJT can stably handle 10A current at $T_{c}=136^{\circ}\mathrm{C}$ while the SiC MOSFET only can handle 7.6A at $T_{c}=110^{\circ}\mathrm{C}$ when considering $40^{\circ}\mathrm{C}$ temperature margin, indicating that the SiC BJT has larger power handling capability because of its more excellent temperature durability.