Abstract: The Early voltage of 4H-SiC BJT,which has an exponential impurity profile in the base,is calculated,taking into account the current gain of the device and four recombination processes in the device.The effects of temperature on the Early voltage and the current gain of the 4H-SiC BJT are investigated.Simulation results show that,keeping the other parameters unchanged,the Early voltage increases with NE (emitter doping density),and decreases when NC (collector doping density) increases and W(base width) decreases.The incomplete ionization of the impurities in 4H-SiC can affect the temperature dependences of the Early voltage and current gain.

Key words: SiC BJT, Early voltage, common-emitter current gain, temperature