Question

The part of a transistor that is heavily doped to produce a large number of majority carriers is

• A. Base
• B. Emitter
• C. Collector
• D. None of these

Answer 1

The correct option is B

Emitter

Explanation for the correct option:

In the case of option B,

1. In comparison to the base and collector, the emitter terminal is the region that is extensively doped.
2. This is because the emitter's job is to give charge carriers to the collector through the base. The emitter is larger than the base but smaller than the collector.
3. The doping is directly related to the concentration of ions. If the region is heavily doped, it means there is a high concentration of ions near the junction.

Explanation for the incorrect options:

In the case of option A,

1. Doping levels rise along with conductivity. Therefore, if the base area is heavily doped, more current will flow to the base terminal. Thus, the collector current (output current) is decreased.

In the case of option C,

1. Since the electrons from the Emitter-Base channel may be repelled by a high concentration of ions in the collector and due to this collector current may drop. So, to avoid this the collector is moderately doped.

In the case of option D,

1. All options are not incorrect because the emitter is dopped heavily to emit a large number of ions.

Hence, option B is the correct answer.