Conduction band

The conduction band is the range of electron energies enough to free an electron from binding with its atom to move freely within the atomic lattice of the material as a 'delocalized electron'. Various materials may be classified by their band gap: this is defined as the difference between the valence and conduction bands.

• In non-conductors, commonly known as insulators, the conduction band is higher than that of the valence band, so it takes infeasibly high energies to delocalize their valence electrons. They are said to have a non-zero band gap.
• In semiconductors, the band gap is small. This explains why it takes a little energy (in the form of heat or light) to make semiconductors' electrons delocalize and conduct electricity, hence the name, semiconductor.
• In metals, the Fermi level is inside at least one band. These Fermi-level-crossing bands may be called conduction band, valence band, or something else depending on circumstance.

Electrons within the conduction band are mobile charge carriers in solids, responsible for conduction of electric currents in metals and other good electrical conductors.

The concept has wide applications in the solid-state physics field of semiconductors and insulators.

Semiconductor band structure
See electrical conduction and semiconductor for a more detailed description of band structure.

See also

• Band theory
• Electrical conduction for more information about conduction in solids, and another description of band structure.
• Fermi sea
• Semiconductor for a full explanation of the band structure of materials.
• Valence band

External links

• Direct Band Gap Energy Calculator