For transistor action:
(a) the base, emitter and collector regions should have similar size and doping concent

Question

For transistor action:
(a) the base, emitter and collector regions should have similar size and doping concentrations.
(b) the base region must be very thin and lightly doped.
(c) the emitter-base junction is forward biased and the base-collector junction is reverse biased.
(d) both the emitter-base junction as well as the base-collector junction are forward biased.
Which of the following pairs of statements is correct?

Accepted Answer

1. **Doping and Size:** For proper transistor action, the three regions have distinct properties. The emitter is heavily doped to inject a large number of charge carriers. The base is very thin and lightly doped to minimize the recombination of carriers. The collector is moderately doped and is the largest in size to dissipate the heat generated during operation. Thus, statement (a) is incorrect, and statement (b) is correct.
2. **Biasing:** For a transistor to operate in its active region (normal transistor action for amplification), the emitter-base junction must be forward-biased to allow majority carriers to flow into the base, and the base-collector junction must be reverse-biased to sweep the carriers into the collector. Thus, statement (c) is correct, and statement (d) is incorrect.
3. **Conclusion:** Statements (b) and (c) are the correct pair.

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