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The conduction of current of intrinsic semiconductor is enabled purely by electron excitation across the band-gap, which is usually small at room temperature except for narrow-bandgap semiconductors, like Hg 0.8 Cd 0.2 Te. The conductivity of a semiconductor can be modeled in terms of the band theory of solids.
The conductivity of a water/aqueous solution is highly dependent on its concentration of dissolved salts, and other chemical species that ionize in the solution. Electrical conductivity of water samples is used as an indicator of how salt-free, ion-free, or impurity-free the sample is; the purer the water, the lower the conductivity (the higher ...
The carrier density is important for semiconductors, where it is an important quantity for the process of chemical doping. Using band theory, the electron density, is number of electrons per unit volume in the conduction band. For holes, is the number of holes per unit volume in the valence band.
The conductivity of semiconductors may easily be modified by introducing impurities into their crystal lattice. The process of adding controlled impurities to a semiconductor is known as doping. The amount of impurity, or dopant, added to an intrinsic (pure) semiconductor varies its level of conductivity. [26]
In an intrinsic or lightly doped semiconductor, μ is close enough to a band edge that there are a dilute number of thermally excited carriers residing near that band edge. In semiconductors and semimetals the position of μ relative to the band structure can usually be controlled to a significant degree by doping or gating.
A compound semiconductor is a semiconductor compound composed of chemical elements of at least two different species. These semiconductors form for example in periodic table groups 13–15 (old groups III–V), for example of elements from the Boron group (old group III, boron, aluminium, gallium, indium) and from group 15 (old group V, nitrogen, phosphorus, arsenic, antimony, bismuth).
Doping of a pure silicon array. Silicon based intrinsic semiconductor becomes extrinsic when impurities such as boron and antimony are introduced.. In semiconductor production, doping is the intentional introduction of impurities into an intrinsic (undoped) semiconductor for the purpose of modulating its electrical, optical and structural properties.
In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determine 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.