In all the fields of electronics, transistors are used in almost all practical purposes. Semiconductor are mainly used to manufacture two devices, those are diodes and transistors. For amplifying a signal, junction diode cannot be used. For that another type of semiconductor device came into account, these type of devices are known as Bipolar Junction Transistor . It has three sections combined at the two ends, which have the same type of majority carriers. The section in the middle has minority carriers, based on this, there are two types of transistors which are named as:
- n-p-n transistor
- p-n-p transistor
In n-p-n junction transistor, p-type has the majority charge carriers and the other two ends have n-type majority carriers. On the other hand, in a p-n-p transistor, n-type has the minority charge carriers whereas the other two hands have p-type majority carriers.
The three sections of a junction transistor are named as emitter (E), base (B), collector (C). In comparison to the emitter and collector, the base of a transistor is made thin and is lightly doped which means that the density of the majority carriers in the base is less than the density of majority carriers in the emitter and collector.
The flow of current is supplied through the emitter and the collector collects them. For proper connection between the emitter and the collector, base provides the interaction for the connectivity. In a junction transistor the arrow points towards the conventional current. In n-p-n transistor’s emitter, the arrow points away from the base and in a p-n-p transistor’s emitter, the arrow points towards the base. The base-emitter junction is usually forward biased and the base-collector junction is reversed biased when the junction transistor is used in a circuit.
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