Characteristics of High-Speed Silicon Carbide (Sic) Power Transistors

This paper describes the temperature and operating characteristics of NPN 4H-SiC (a polytype of silicon carbide) bipolar junction transistor (BJT) and 4H-SIC Darlington pairs. A large amount of experimental data was collected. The wafer BJTs were able to block over the rated 600 V in the common-emitter configuration and the TO-220 BJTs were able to block over the 1200 V rated voltage. In the thermal analysis, it is found out that at higher temperatures the forward and blocking characteristics were stable at 100degC and 200degC. The transistors show positive temperature coefficients of forward voltage (V). In general the current gain (beta) characteristics obtained (with ^fV_CE = 6 V) were approximately as expected for the BJTs. The beta ´s were very low (2 to 5 for wafer BJTs, 5 to 20 for the wafer Darlington pairs, and 5 to 30 for TO-220 BJTs). The large amount of experimental data collected confirms some of the superior properties of the SiC material when used to fabricate power semiconductor devices, namely high thermal conductivity and high operating temperature capability. The SiC BJT has fast switching and recovery characteristics.