Characteristics of base current components in planar bipolar transistors

The paper analyzes the role of two current components in the base current at low polarization levels: a surface current, and a current due to bulk effects. A numerical identification method allows quantitative study of the effect of temperature, surface potential (for tetrode transistors), and ionizing radiation on the characteristics of these two components. The results show that the surface component is due to recombinations taking place in the surface region of the transition zone of the emitter-base junction, while the bulk component is related to the injection efficiency of the active region of the emitter-base junction.