Semiconductor

n. solid material with electrical conductivity that is between that of a conductor and an insulator at normal temperatures

A semiconductor is a solid that has electrical conductivity in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically. Semiconductors are tremendously important in technology. Semiconductor devices, electronic components made of semiconductor materials, are essential in modern electrical devices. Examples range from computers to cellular phones to digital audio players.  Silicon is used to create most semiconductors commercially, but dozens of other materials are used as well.
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Noun
1. a substance as germanium or silicon whose electrical conductivity is intermediate between that of a metal and an insulator; its conductivity increases with temperature and in the presence of impurities
(synonym) semiconducting material
(hypernym) conductor
(hyponym) germanium, Ge, atomic number 32
(substance-holonym) semiconductor device, semiconductor unit
2. a conductor made with semiconducting material
(synonym) semiconductor device, semiconductor unit
(hypernym) conductor
(hyponym) chip, microchip, micro chip, silicon chip
(substance-meronym) semiconducting material

n. semiconductor, solid material with electrical conductivity that is between that of a conductor and an insulator at normal temperatures

<electronics> A material, typically crystaline, which allows current to flow under certain circumstances. Common semiconductors are silicon, germanium, gallium arsenide. Semiconductors are used to make diodes, transistors and other basic "solid state" electronic components.
As crystals of these materials are grown, they are "doped" with traces of other elements called donors or acceptors to make regions which are n- or p-type respectively for the electron model or p- or n-type under the hole model. Where n and p type regions adjoin, a junction is formed which will pass current in one direction (from p to n) but not the other, giving a diode.
One model of semiconductor behaviour describes the doping elements as having either free electrons or holes dangling at the points in the crystal lattice where the doping elements replace one of the atoms of the foundation material. When external electrons are applied to n-type material (which already has free electrons present) the repulsive force of like charges causes the free electrons to migrate toward the junction, where they are attracted to the holes in the p-type material. Thus the junction conducts current.
In contrast, when external electrons are applied to p-type material, the attraction of unlike charges causes the holes to migrate away from the junction and toward the source of external electrons. The junction thus becomes "depleted" of its charge carriers and is non-conducting.
(1995-10-04)