Semiconductor
Definition and meaning of Semiconductor in chemistry.
A semiconductor is a material with electrical conductivity between that of a conductor and an insulator, whose conductivity increases dramatically with thermal energy or doping. Common examples include silicon, germanium, and gallium arsenide.
In more detail
In semiconductors, electrons in the valence band must overcome an energy barrier called the band gap to reach the conduction band, where they contribute to electrical current. Heat provides this energy, which is why semiconductor conductivity increases with temperature, unlike metals. Semiconductors can also be intentionally doped by adding impurities: n-type doping adds donor atoms like phosphorus to provide free electrons, while p-type doping adds acceptors like boron to create electron vacancies (holes). This controllable conductivity makes semiconductors indispensable for transistors, diodes, integrated circuits, and solar cells.
Key facts
| Field | Physical Chemistry |
|---|---|
| Common Examples | Silicon (Si), germanium (Ge), gallium arsenide (GaAs) |
| Band Gap | Minimum energy electrons need to move from valence to conduction band |
| Doping Types | n-type (donor atoms provide electrons) or p-type (acceptor atoms create holes) |
Silicon (Si) is the primary semiconductor in modern electronics; pure silicon at room temperature has moderate conductivity, but doping it with phosphorus creates n-type material, while doping with boron creates p-type material for junction-based devices like transistors.
Frequently asked questions
Why does semiconductor conductivity increase with temperature?
Thermal energy helps electrons jump across the band gap to the conduction band. As temperature increases, more electrons gain sufficient energy, increasing conductivity.
What is the difference between semiconductors and conductors?
Conductors have free electrons at room temperature and conduct readily. Semiconductors require energy input (heat or doping) to conduct, making their conductivity controllable and tunable.