Which are the Facts about the Transistor?

Which are the Facts about the Transistor?

- Before discussing transistor action, it is important that the reader may keep in mind the following facts about the transistor:
(i) The transistor has three regions, namely; emitter, base and collector. The base is much thinner than the emitter while **collector is wider than both as shown in Fig. 4.3. However, for the sake of convenience, it is customary to show emitter and collector to be of equal size.

(ii) The emitter is heavily doped so that it can inject a large number of charge carriers (electrons or holes) into the base. The base is lightly doped and very thin; it passes most of the emitter injected charge carriers to the collector. The collector is moderately doped.



(iii) The transistor has two pn junctions i.e. it is like two diodes. The junction between emitter and base may be called emitter-base diode or simply the emitter diode. The junction between the base and collector may be called collector-base diode or simply collector diode.

(iv) The emitter diode is always forward biased whereas collector diode is always reverse biased.

(v) The resistance of emitter diode (forward biased) is very small as compared to collector diode (reverse biased). Therefore, forward bias applied to the emitter diode is generally very small whereas reverse bias on the collector diode is much higher.

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Wilfykil answered the question on August 14, 2019 at 12:28

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