Intrinsic Semiconductor

An intrinsic semiconductor, also called an undoped semiconductor or i-type semiconductor, is a pure semiconductor without any significant dopant species present. The number of charge carriers is therefore determined by the properties of the material itself instead of the amount of impurities. In intrinsic semiconductors the number of excited electrons and the number of holes are equal: n = p.

The electrical conductivity of intrinsic semiconductors can be due to crystallographic defects or electron excitation. In an intrinsic semiconductor the number of electrons in the conduction band is equal to the number of holes in the valence band. An example is Hg0.8Cd0.2Te at room temperature.

An indirect band gap intrinsic semiconductor is one in which the maximum energy of the valence band occurs at a different k (k-space wave vector) than the minimum energy of the conduction band. Examples include silicon and germanium. A direct band gap intrinsic semiconductor is one where the maximum energy of the valence band occurs at the same k as the minimum energy of the conduction band. Examples include gallium arsenide.

A silicon crystal is different from an insulator because at any temperature above absolute zero temperature, there is a finite probability that an electron in the lattice will be knocked loose from its position, leaving behind an electron deficiency called a "hole".

If a voltage is applied, then both the electron and the hole can contribute to a small current flow.

The conductivity of a semiconductor can be modeled in terms of the band theory of solids. The band model of a semiconductor suggests that at ordinary temperatures there is a finite possibility that electrons can reach the conduction band and contribute to electrical conduction.

The term intrinsic here distinguishes between the properties of pure "intrinsic" silicon and the dramatically different properties of doped n-type or p-type semiconductors.

Read more about Intrinsic SemiconductorElectrons and Holes, Semiconductor Current

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Extrinsic Semiconductor - Semiconductor Doping
... Semiconductor doping is the process that changes an intrinsic semiconductor to an extrinsic semiconductor ... During doping, impurity atoms are introduced to an intrinsic semiconductor ... a different element than the atoms of the intrinsic semiconductor ...
Intrinsic Semiconductor - Semiconductor Current
... The current which will flow in an intrinsic semiconductor consists of both electron and hole current ... The current flow in an intrinsic semiconductor is influenced by the density of energy states which in turn influences the electron density in the conduction band ...
Semiconductor - Doping - Carrier Concentration
... The concentration of dopant introduced to an intrinsic semiconductor determines its concentration and indirectly affects many of its electrical properties ... In an intrinsic semiconductor under thermal equilibrium, the concentration of electrons and holes is equivalent ... That is, If we have a non-intrinsic semiconductor in thermal equilibrium the relation becomes where n0 is the concentration of conducting electrons, p0 is ...

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