CBSE Class 12 · 2006 · All India · SemiconductorsShort Answer

What is the function of the base region of a transistor? Why is this region made thin and slightly doped?

Solution

The base governs the number of majority carriers passing from the emitter to the collector, which makes transistor action possible.
If the base is thin and lightly doped it contains few majority carriers, so recombination there is small and about 95–98% of the injected carriers cross into the collector, giving a large collector current.

Thin, lightly doped base \Rightarrow minimal recombination, large I_{C} .

CBSE Class 12 Board · 2006 · All India · Subjective

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