science · 30 March 1950 · 74 years ago
In 1950, the invention of the phototransistor was announced. This was a transistor operated by light rather than electric current, invented by Dr. John Northrup Shive of the Bell Telephone Laboratories at Murray Hill, N.J. It used a tiny chip of germanium, a semiconductor material, but only a single collector wire. The tip of this wire rests in a small dimple ground into one side of the germanium disk. At this point the germanium disk is only three thousandths of an inch thick. Light focussed on the opposite, un-dimpled side of the disk can control the flow of current in the wire, thus making a control device similar in function to a photo-electric cell.
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