Semiconductor

Semiconductors are materials that are not insulators or conductors, but somewhere in the middle. What makes semiconductors useful for electronic purposes is that they have the property of being able to carry an electric current by electron propagation or "hole" propagation. Electron propagation is the same sort of current flow seen in a standard copper wire - heavily ionized atoms? pass excess electrons down the wire from one atom to another in order to move from a more negatively ionized area to a less negatively ionized area. "Hole" propagation is a rather different proposition - in the case of a semiconductor experiencing hole propagation, the charge moves from a more positively ionized area to a less positively ionized area by the movement of the [electron hole]? created by the absence of an electron in a nearly-full electron shell.

While silicon dioxide or sand? is an insulator, pure silicon is a semiconductor.

The properties of semiconductors, e.g. the number of carriers (and therefore the prevalence of electron propagation or hole propagation), can be controlled by "doping" the semiconductor blocks with impurities. A semiconductor with more electrons than holes is called an [n-type semiconductor]?, while a semiconductor with more holes than electrons is called a [p-type semiconductor]?.

Semiconductors are the fundamental materials in many modern electronic devices.

See also semiconductor device fabrication, [semiconductor devices]?, transistors, diodes, microprocessors, electrical engineering, tunneling.