Short Answer

Intrinsic semiconductors are pure semiconductor materials without any added impurities. Their conductivity depends only on temperature, and they have an equal number of electrons and holes. Examples include pure silicon and germanium.

Extrinsic semiconductors are formed by adding small amounts of impurities to intrinsic semiconductors through a process called doping. This increases their conductivity. In these semiconductors, the number of electrons and holes is not equal, and they are classified as N-type or P-type.

Detailed Explanation

Intrinsic and extrinsic semiconductors difference

Intrinsic semiconductor

An intrinsic semiconductor is a pure form of semiconductor material. It does not contain any impurity atoms. In this type, electrical conduction happens due to thermally generated charge carriers. At very low temperature, it behaves like an insulator because there are no free electrons available for conduction.

When temperature increases, some electrons gain energy and move from the valence band to the conduction band. This movement creates a free electron and leaves behind a hole. Therefore, in intrinsic semiconductors, the number of electrons is always equal to the number of holes. These charge carriers help in conducting electricity.

The conductivity of intrinsic semiconductors is low because the number of free charge carriers is small. Materials like pure silicon and germanium are common examples. Due to their low conductivity, intrinsic semiconductors are not widely used directly in electronic devices.

Extrinsic semiconductor

An extrinsic semiconductor is formed by adding a small amount of impurity atoms to a pure semiconductor. This process is called doping. The main purpose of doping is to increase the number of charge carriers and improve conductivity.

There are two types of extrinsic semiconductors based on the type of impurity added. In an N-type semiconductor, elements like phosphorus are added, which have extra electrons. These extra electrons become free and increase conductivity. In this case, electrons are the majority carriers.

In a P-type semiconductor, elements like boron are added, which have fewer electrons. This creates more holes in the material. Here, holes act as majority carriers and help in conduction.

Extrinsic semiconductors have much higher conductivity compared to intrinsic semiconductors. They are widely used in devices like diodes, transistors, and integrated circuits.

Main differences

The main difference between intrinsic and extrinsic semiconductors is purity. Intrinsic semiconductors are pure, while extrinsic semiconductors are doped with impurities. Another difference is conductivity, where intrinsic semiconductors have low conductivity and extrinsic semiconductors have high conductivity.

In intrinsic semiconductors, the number of electrons and holes is equal, but in extrinsic semiconductors, they are unequal. Also, intrinsic semiconductors depend mainly on temperature for conduction, while extrinsic semiconductors depend on doping.

Conclusion

Intrinsic semiconductors are pure materials with limited conductivity, whereas extrinsic semiconductors are doped materials with improved and controllable conductivity. Because of their better performance, extrinsic semiconductors are widely used in modern electronic devices and circuits.