A new reliability study in SiGe heterojunction bipolar transistors (HBTs) is investigated resulting from electromagnetic field aggression. We demonstrate experimental evidence of current gain degradation during electromagnetic stress. The device degradation is due to the hot carrier (HC) injected into the emitter-base spacer oxide, which induces generation/recombination trap centers, and leads to excess non-ideal base currents. Two-dimensional simulations, based on the HBT cross section, have been used to help understand the device physics associated with this degradation mechanism. As a consequence of introducing the surface recombination centers at the emitter-base spacer oxide, a non-ideal base current arises in agreement with the experimental data extracted. Simulation results show a strong correlation between stress time and recombination rate induced by the Si/SiO2 interface damage.