Semiconductors

Semiconductors

1. A semiconductor is a class of crystalline solid with conductivity between a conductor and an insulator.
2. Example of semiconductors are:
1. Silicon
2. Germanium
3. Boron
4. Tellurium
5. Selenium

The Silicon Crystal

1. The typical example of semiconductor is silicon.
2. Silicon has 4 valence electrons. Each of these 4 electrons are shared with another 4 silicon atoms to form 4 pairs of covalent bond, as shown in the diagram above.
3. The bonded valence electrons are not free to move. Therefore silicon is not a good conductor at room temperature.
4. At room temperature, a silicon crystal acts approximately like an insulator because only a few free electrons and holes are presence.