The paper presents a study of the different aspects of the temperature dependent performance of a 4H-SiC epi-emitter Bipolar Junction Transistor particularly the low temperature performance. Some critical device physics related factors that affect the forward active performance of the device are explored and the device behavior is modeled up to 100K. We present for the first time the experimental low-temperature (down to 100K) performance of 4H-SiC epi-emitter BJTs and the determination of the temperature beyond which the current gain starts to increase with temperature. We have also corroborated these results with 2-dimensional device simulations.