P–n junction

A p–n junction is a special type of electric circuit that is made up of two different types of materials—p-type and n-type. These types of materials are also called semiconductors because they can help control the movement of electricity. The p-type material has a lot of extra holes (kind of like little pockets) to move electricity around, while the n-type material has a lot of extra electrons ready to carry current. When they are put together, they create an electric field that can do special things to control the flow of electricity.