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A homojunction is a
A homojunction is a semiconductor
A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...
interface that occurs between layers of similar semiconductor material;Yang 1978, p. 141. these materials have equal band gap
In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to t ...
s but typically have different doping. In most practical cases a homojunction occurs at the interface between an n-type ( donor doped) and p-type (acceptor
Acceptor may refer to:
* Acceptor (accounting), the addressee of a bill of exchange
* In the Indian Contract Act of 1872, the acceptor is the person to whom a proposal is made, and who has communicated his or her acceptance of the said proposal
* ...
doped) semiconductor such as silicon
Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...
, this is called a p–n junction.
This is not a necessary condition as the only requirement is that the same semiconductor (same band gap
In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to t ...
) is found on both sides of the junction, in contrast to a heterojunction. An n-type to n-type junction, for example, would be considered a homojunction even if the doping levels are different.
The different doping level will cause band bending, and a depletion region
In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region, or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobil ...
will be formed at the interface, as shown in the figure to the right.
See also
*Transistor
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...
* p–n junction
* Band bending
* Doping (semiconductor)
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. The doped material is referred to as a ...
Notes
References
* Yang, Edward S (1978). ''Fundamentals of semiconductor devices''. McGraw-Hill. ISBN 0070722366External links
* {{Commonscatinline, PN-junction band diagrams Semiconductor structures