An insight into the high temperature performance of SiC bipolar junction transistor

Technology computer aided design (TCAD) tools were applied in a systematic manner to gain an insight on the effect of high temperature on the operation of SiC bipolar junction transistors (BJT) and obtain useful parameters directly. Simple physical models (Schockley Read Hall recombination, Auger recombination, incomplete ionization, bandgap narrowing, temperature and doping dependent mobility models, etc.) available for BJT were employed to study the device characteristics. This was done by carefully selecting the size of the mesh, which is very important to determine the properties at the SiC-SiO₂ interface. Results show that, at elevated temperatures, the e-current contours increase the area deep in the collector region and the SRH recombination processes are high at the SiC-SiO₂ interface, both of which play big roles in degrading the device performance. The gain drops by about 30% in the temperature range from 150 K to 700 K. This is due to the increased ionization level of deep acceptor atoms in the base (i.e., increased hole concentration in the emitter and hence larger hole component of the emitter current), resulting in the reduced emitter injection efficiency. The value of on-resistance also increases with increase in the temperature initially and then saturates at around 500 K.