Definition: semiconductor
Semiconductors are materials that have electrical conductivity between that of a conductor and an insulator. They are commonly used in electronic devices such as transistors, diodes, and integrated circuits. The most well-known semiconductor material is silicon, but other materials such as germanium and gallium arsenide are also used. Semiconductors have played a major role in the development of modern electronics and continue to be a crucial component in many technologies.
Types of Semiconductors
There are two main types of semiconductors: intrinsic and extrinsic.
Intrinsic semiconductors are pure semiconductor materials, such as silicon or germanium, that have had no impurities added. These materials have a very small number of free electrons and holes, making them poor conductors of electricity.
Extrinsic semiconductors are formed by adding impurities, known as dopants, to intrinsic semiconductors. There are two types of extrinsic semiconductors: p-type and n-type.
P-type semiconductors are created by adding impurities such as boron, which has one less electron than the semiconductor atoms. This creates a “hole” in the crystal lattice where an electron is missing, which can carry electrical current.
N-type semiconductors are created by adding impurities such as phosphorus, which has one more electron than the semiconductor atoms. This creates an excess of free electrons, which can also carry electrical current.
Both p-type and n-type semiconductors are used in electronic devices, and when combined, they can create p-n junctions which forms the basis of many electronic devices like transistors, solar cells and diodes.