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The '''transistor''' was invented at Bell Labs in Murray Hill, New Jersey, by scientists William Shockley, Walter Brattain, and John Bardeen from the University of Minnesota.
The '''transistor''' is a device used to switch electrical signals on and off, or to amplify them (make them larger). It was invented at Bell Labs in Murray Hill, [[New Jersey]], by scientists William Shockley, Walter Brattain, and John Bardeen from the University of Minnesota.
==Function==
Modern transistors are so small that designers make heavy use of [[quantum mechanics|quantum theory]]. However, this isn't important for everyday use of the devices and a simple explanation of transistors is given below. There are two basic types of transistor: field-effect transistors (FETs) and bipolar junction transistors (BJTs).
=== Field-effect transistors ===
A field effect transistor contains a thin strip of [[semiconductor]] called the "channel". A pair of metal contacts are put at either end of the channel, allowing it to be connected into a [[circuit]]. These contacts are called the "source" and the "drain". The rest of the channel is coated with an [[insulator]] to stop any unwanted currents from entering or leaving.
Finally, a third metal contact called the "gate" is placed on top of the insulator. When a battery is connected between the gate and source, the insulator stops current getting through. Instead, the electrons in the channel are all pushed away from the gate. In other words, they can only move through a very thin part of the channel, making it difficult for current to flow between the source and drain. The [[resistance]] of the channel therefore depends on the [[voltage]] at the gate. If a big enough voltage is placed on the gate, the electrons can be pushed completely out of the channel and no current can flow at all.
The first transistors were made of [[germanium]], but more modern devices are made of [[silicon]]. Some modern devices use [[silicon-germanium]] alloys or [[gallium arsenide]].
==History==
==History==
==Significance==
==Significance==
Transistors created a revolution in electronics.
Transistors created a revolution in [[electronics]].
Prior to the transistor, electronics relied on vacuum tubes. Vacuum tubes made possible very sophisticated electronics, including broadcast radio and television as we know them, radar, and the first electronic computers.
Prior to the transistor, electronics relied on vacuum tubes. Vacuum tubes made possible very sophisticated electronics, including broadcast radio and television as we know them, radar, and the first electronic computers.
[[Category:Technology]]
[[Category:Technology]]
[[Category:Electronics]]