Impact of Temperature on Dynamics and Reliability of High-Voltage Silicon & 4H-SiC Bipolar Junction Transistors

This paper analyses the impact of high temperature on the dynamic characteristics and performance of the highest voltage bipolar junction transistors available commercially: an 800 V, 20 A Fairchild Silicon BJT and a 1.7 kV, 15 A GeneSiC 4H-SiC BJT, under conditions of high injection levels, unclamped inductive switching, and short circuit at case temperatures of at least 150°C. The high temperature investigations are conducted through measurements at a range of base resistance and collector currents. Clamped inductive switching tests have been performed at 800 V with a maximum collector current of 14 A, varying the switching rates. In the unclamped inductive switching and short circuit tests, the stress level is increased by either raising the DC-link voltage or extending the pulse length until device failure. According to the dynamic transient results, 4H-SiC BJTs outperform their Silicon counterparts, exhibiting a DC current gain at least ten times higher than that of Silicon and faster switching performance without delay in transitions. The withstand energy density in reliability tests are also higher in SiC thanks to significantly smaller die size.