Definition: semiconductor

A solid state material that can be electrically altered. Certain elements in nature, such as silicon and germanium become semiconductors when chemically combined with other elements. Various optical materials can also change their state (see phase change disc).

When electricity or light is applied to semiconductors, they change their state between conductive and non-conductive or reflective and non-reflective. The most significant semiconductor device is the transistor, which in digital circuits is an on/off switch. Today, the semiconductor and chip industries are generally considered one and the same. However, although all chips are semiconductors, not all semiconductors are chips because individual transistors packaged separately are still widely used (see discrete transistor). See chip and chip manufacturing.

Analog Semiconductors Are Amplifiers
For analog applications, a semiconductor is used as an amplifier, taking in a low-power signal and sending out a higher power (see amplifier). See n-type silicon.

Like an On/Off Switch

Silicon can be altered to either conduct or not conduct electricity, making it operate like an on/off switch not much different than a light switch on the wall.