Transistors

Transistor

For other uses, see Transistor (disambiguation).

Assorted discrete transistors. Packages in order from top to bottom: TO-3,TO-126, TO-92, SOT-23.

A transistor is a semiconductor device used to amplify orswitch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

The transistor is the fundamental building block of modernelectronic devices, and is ubiquitous in modern electronic systems. Following its development in 1947 by Americanphysicists John Bardeen, Walter Brattain, and William Shockley, the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios,calculators, and computers, among other things. The transistor is on the list of IEEE milestones in electronics,^[1]and the inventors were jointly awarded the 1956 Nobel Prize in Physics for their achievement.^[2]

History

Main article: History of the transistor

 

A replica of the first working transistor.

The thermionic triode, a vacuum tube invented in 1907, enabled amplified radio technology and long-distancetelephony. The triode, however, was a fragile device that consumed a lot of power. Physicist Julius Edgar Lilienfeldfiled a patent for a field-effect transistor (FET) in Canada in 1925, which was intended to be a solid-state replacement for the triode.^[3][4] Lilienfeld also filed identical patents in the United States in 1926^[5] and 1928.^[6][7] However, Lilienfeld did not publish any research articles about his devices nor did his patents cite any specific examples of a working prototype. Because the production of high-quality semiconductor materials was still decades away, Lilienfeld's solid-state amplifier ideas would not have found practical use in the 1920s and 1930s, even if such a device had been built.^[8] In 1934, German inventor Oskar Heil patented a similar device.^[9]

John Bardeen, William Shockley andWalter Brattain at Bell Labs, 1948.

From November 17, 1947 to December 23, 1947, John Bardeen and Walter Brattain at AT&T's Bell Labs in the United States performed experiments and observed that when two gold point contacts were applied to a crystal of germanium, a signal was produced with the output power greater than the input.^[10] Solid State Physics Group leader William Shockleysaw the potential in this, and over the next few months worked to greatly expand the knowledge of semiconductors. The term transistor was coined by John R. Pierce as a contraction of the term transresistance.^[11][12][13] According to Lillian Hoddeson and Vicki Daitch, authors of a biography of John Bardeen, Shockley had proposed that Bell Labs' first patent for a transistor should be based on the field-effect and that he be named as the inventor. Having unearthed Lilienfeld’s patents that went into obscurity years earlier, lawyers at Bell Labs advised against Shockley's proposal because the idea of a field-effect transistor that used an electric field as a "grid" was not new. Instead, what Bardeen, Brattain, and Shockley invented in 1947 was the first point-contact transistor.^[8] In acknowledgement of this accomplishment, Shockley, Bardeen, and Brattain were jointly awarded the 1956 Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect."^[14]