The difference and function between PNP and NPN transistors in triodes

The main reason is that the semiconductor types of each pole are different. The E, B, and C poles of PNP transistors are P-type, N-type, and P-type semiconductors, respectively, while NPN transistors are exactly the opposite.

P-type semiconductors refer to carriers that are mainly holes, while N-type semiconductors are mainly electrons.

The main difference between the two types of transistors is that the potentials of each pole are exactly opposite. The base of a PNP transistor needs to be connected to a negative potential, while the base of an NPN transistor needs to be connected to a positive potential.

The difference between PNP and NPN is defined on the surface by the direction of the PN junction, but in reality, it is distinguished by the structural material of the transistor. PNP has gallium on both sides and silicon in the middle. Gallium is an element of the third main group, with three electrons outside its nucleus,

Silicon is an element of the fourth main group, with four electrons outside its core, so the order in the two PN directions is P-N-N relationship; On the contrary, NPN has silicon on both sides and gallium in the middle, forming a PN junction in the order of N-P-N.

By the way, P means a material that lacks electrons at the PN junction and conducts electricity mainly through holes, also known as P-type material; The meaning of N is a material with excess electrons at the PN junction, mainly conducting electricity through electrons, also known as N-type material.