The mobility of electrons is better than the mobility of holes, therefore, NPN transistor works faster as compared to PNP transistors.

In NPN transistors the majority charge carriers are electrons and in PNP transistors the majority charge carriers are holes. Usually, NPN transistors are used because it is easy to design them. The current flows in the direction from the collector to the emitter. The NPN transistor turns on when the current flow through the base of the transistor. If the arrow is pointing outside then it is NPN transistor and if it is pointing inwards then it is PNP transistor.Ī transistor, in which there is one p-type semiconductor that is doped by two n-type semiconductors from both sides are called NPN transistors. To identify whether it is NPN or PNP we use this arrow. The arrow shows the direction of the electric current and the electric current always flows from positive to negative. Here, which has an arrow is known as emitter, the base is always in the center.

The base size is small and it is lightly doped, the emitter size is moderate (between the base size and the collector size) and the doping is strong, collector size is large as compared to base and emitter and the doping is moderate (between the base and emitter doping). Here the collector and the emitter old of p-type and the base are of n-type. In PNP transistors instead of electrons, the emitter emits holes and they are collected by the collector. The PNP transistor turns on when there is no current at the base of the transistor. In PNP transistor they are two differences between both P, that is doping and the size of both p is different.Ī transistor in which there is one n-type semiconductor that is doped by two p-type semiconductors from both sides is called PNP transistor. Thee are two types of transistors NPN and PNP transistor. The emitter emits the charges and these charges are collected by the collector. The transistor has three regions that are emitter, base, collector. In a transistor, one semiconductor is sandwiched from both sides by another semiconductor. With the help of diodes, amplification of the signal is not possible and that is the reason we use transistors. Semiconductors are basically used in manufacturing two devices that are diodes and transistors.

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