Valence and Conduction Bands
– Valence band and conduction band determine the electrical conductivity of a solid.
– In nonmetals, the valence band is the highest range of electron energies present at absolute zero temperature.
– The conduction band is the lowest range of vacant electronic states.
– In semiconducting materials, the valence band is located below the Fermi level, while the conduction band is located above it.
– In metals, conduction occurs in one or more partially filled bands that have properties of both valence and conduction bands.
Band Gap
– Semiconductors and insulators have a band gap that separates the valence and conduction bands.
– The band gap is an energy range where no electron states can exist.
– Electrical conductivity in non-metals depends on the ability of electrons to be excited from the valence band to the conduction band.
– Conductors have overlapping valence and conduction bands.
– The energy gap between the valence and conduction bands is the band gap.
Electrical Conductivity
– The ability of electrons to act as charge carriers depends on the availability of vacant electronic states.
– Electrons can increase their energy and accelerate when an electric field is applied.
– Holes in the valence band also contribute to conductivity.
– Semimetals with overlap regions have high electrical conductivity.
– Semiconductors have a small band gap and require external energy for electron flow, while insulators have a large band gap and negligible electron flow.
Band Edge Shifts of Semiconductor Nanoparticles
– Semiconductor nanocrystals exhibit size-dependent conduction and valence band edge shifts.
– The edge shifting occurs when the nanocrystal is restricted by the exciton.
– The conduction and valence band edges shift to higher energy levels under the radius limit of the nanocrystal.
– This edge shifting provides information about the size or concentration of semiconductor nanoparticles.
– The size-dependent edge shifting of the band structure is useful in understanding the properties of semiconductor nanocrystals.
Related Concepts
– Electrical conduction provides more information about conduction in solids and band structure.
– Fermi sea is a concept related to the distribution of electrons in energy levels.
– HOMO/LUMO refers to the highest occupied molecular orbital and lowest unoccupied molecular orbital.
– Semiconductor offers a comprehensive explanation of the band structure of materials.
– Valleytronics is a field of research exploring the manipulation of electrons in energy valleys. Source: https://en.wikipedia.org/wiki/Conduction_electron
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (December 2021) |
In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determines the electrical conductivity of the solid. In nonmetals, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature, while the conduction band is the lowest range of vacant electronic states. On a graph of the electronic band structure of a semiconducting material, the valence band is located below the Fermi level, while the conduction band is located above it.
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.
