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In a uniformly doped BJT, assume that NE, NB and NC are the emitter, base and collector doping in atoms/cm3, respectively. If the emitter injection efficiency of the BJT is close to unity, which one of the following conditions is TRUE?

In a uniformly doped BJT, assume that NE, NB and NC are the emitter, base and collector doping in atoms/cm3, respectively. If the emitter injection efficiency of the BJT is close to unity, which one of the following conditions is TRUE? Correct Answer N<sub>E </sub>≫ N<sub>B</sub> and N<sub>B </sub>&lt; N<sub>C</sub>

The emitter injection efficiency is a measure of how efficient the emitter is in injecting electrons into the base.

It is important because the entire transistor action is due to the electrons injected into the base.

The holes, which are simultaneously injected into the emitter, are useless from this point of view.

In BJT the doping profile are related as-

NE> NC> NB

Now, as emitter injection efficiency of the BJT is close to unity we can say

NE≫ NB

Thus, NE≫ NB and NB < NC

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