Bipolar junction transistor structure with improved current gain characteristics

1. Technical Field of the Invention A Bipolar Junction Transistor (BJT) that reduces the variation in the current gain through the use of a trench pullback structure. The trench pullback structure is comprised of a trench and an active region. The trench reduces recombination in the emitter-base region through increasing the distance charge carriers must travel between the emitter and the base. The trench also reduces recombination by reducing the amount of interfacial traps that the electrons injected from the emitter are exposed to. Further, the trench is pulled back from the emitter allowing an active region where electrons injected from a sidewall of the emitter can contribute to the overall injected emitter current. This structure offers the same current capability and current gain as a device without the trench between the emitter and the base while reducing the current gain variation.