A PNP transistor is fabricated with an increased base doping concentration while keeping all other physical dimensions and doping levels constant. What is the effect on the transistor's performance?
The common-emitter current gain decreases
When base doping concentration of a PNP transistor is increased:
- More acceptor atoms in the base → more recombination centres for minority carriers (electrons injected from emitter).
- Base transport factor (αT) decreases — fewer carriers reach the collector.
- Common base current gain α decreases → Common emitter current gain β = α/(1−α) decreases.
The emitter injection efficiency and base transport factor both decrease with higher base doping, leading to lower β (hFE).
Similar Questions
A PNP transistor is operating in active region. If the emitter voltage decreases such that the emitter becomes less positive than the base while the biasing condition of the collector-base junction remains unchanged, the transistor will enter _______.
In a properly biased PNP transistor operating in active region, the emitter terminal is _______.
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