1. Electrical conductivity between that of a conductor and an insulator: Semiconductors have a conductivity that is significantly higher than insulators but lower than conductors. This means they can conduct electricity under certain conditions, but not as freely as metals.
2. Electrical conductivity increases with temperature: Unlike metals, where conductivity decreases with increasing temperature, semiconductors show an increase in conductivity as temperature rises. This is because more electrons gain enough energy to jump into the conduction band.
3. Ability to be doped: Semiconductors can be doped with impurities to alter their conductivity. Doping involves adding small amounts of other elements to the semiconductor's crystal structure. This can create either n-type semiconductors with an excess of free electrons or p-type semiconductors with an excess of holes (electron vacancies).
4. Band structure with a small band gap: The energy difference between the valence band (where electrons reside at rest) and the conduction band (where electrons can freely move) is called the band gap. Semiconductors have a relatively small band gap, allowing electrons to move into the conduction band with moderate amounts of energy (like heat or light).
In simpler terms:
Semiconductors are materials that are "in between" conductors and insulators. They can be made to conduct electricity better by adding impurities, and their ability to conduct electricity increases with temperature. This unique combination of properties makes them essential for modern electronics.
