Valence and conduction bands
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (December 2021) |
In
The distinction between the valence and conduction bands is meaningless in metals, because conduction occurs in one or more partially filled bands that take on the properties of both the valence and conduction bands.
Band gap
In semiconductors and insulators the two bands are separated by a band gap, while in conductors the bands overlap. A band gap is an energy range in a solid where no electron states can exist due to the quantization of energy. Within the concept of bands, the energy gap between the valence band and the conduction band is the band gap.[1] Electrical conductivity of non-metals is determined by the susceptibility of electrons to be excited from the valence band to the conduction band.
Electrical conductivity
In solids, the ability of electrons to act as
As such, the
There is some conductivity in semiconductors, however. This is due to thermal excitation—some of the electrons get enough energy to jump the band gap in one go. Once they are in the conduction band, they can conduct electricity, as can the hole they left behind in the valence band. The hole is an empty state that allows electrons in the valence band some degree of freedom.
Band edge shifts of semiconductor nanoparticles
The edge shifting of size-dependent conduction and/or valence band is a phenomenon being studied in the field of semiconductor nanocrystals. The radius limit of occurrence of the semiconductor nanocrystal is the effective Bohr radius of the nanocrystal. The conduction and/or valence band edges shift to higher energy levels under this radius limit due to discrete optical transitions when semiconductor nanocrystal is restricted by the exciton. As a result of this edge shifting, the size of the conduction and/or valence band is decreased. This size-dependent edge shifting of conduction and/or valence band can provide plenty of useful information regarding the size or concentration of the semiconductor nanoparticles or band structures.[2]
See also
- Electrical conductionfor more information about conduction in solids, and another description of band structure.
- Fermi sea
- HOMO/LUMO
- Semiconductor for a full explanation of the band structure of materials.
- Valleytronics
References
Citations
General references
- Kittel, Charles (2005). ISBN 0-471-41526-X.
- Kornic, Steve (11 April 1997). "The Valence Band". Chembio. Archived from the original on 4 March 2021. Retrieved 8 December 2021.
- Nave, Carl R. (Rod) (1999). "Band Theory for Solids". Hyperphysics. Retrieved 8 December 2021.