 - A semiconductor is a substance, usually a solid chemical element
or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current. Its conductance
varies depending on the current or voltage applied to a control electrode, or on the intensity of
irradiation by infrared (IR), visible light, ultraviolet (UV), or X rays.
The specific properties of a semiconductor depend on the
impurities, or dopants, added to it. An N-type semiconductor carries current mainly in the form of
negatively-charged electrons,
in a manner similar to the conduction of current in a wire. A P-type
semiconductor carries current predominantly as electron deficiencies called holes. A hole has a positive electric charge, equal and opposite to the charge on an electron. In
a semiconductor material, the flow of holes occurs in a direction opposite
to the flow of electrons.
Elemental semiconductors include antimony, arsenic, boron, carbon,
germanium, selenium, silicon, sulfur, and tellurium. silicon is the best-known of these, forming the basis of most integrated circuits (ICs). Common semiconductor compounds include gallium arsenide, indium antimonide, and the oxides of most metals. Of these, gallium arsenide (GaAs) is widely used in low-noise, high-gain, weak-signal amplifying devices.
A semiconductor device can perform the function of a vacuum tube having hundreds of times its volume. A single integrated circuit (IC), such as a microprocessor chip, can do the work of a set of vacuum tubes that would fill a large building and require its own electric generating plant.
See also atom, transistor, bipolar transistor, and field-effect transistor.
| LAST UPDATED: |
02 Sep 2002
|
|
Do you have something to add to this definition? Let us know.
Send your comments to techterms@whatis.com
|
|
