File:Sectionalized transistor besides an ordinary paper clip – Bell Telephone Magazine (Spring 1950, p. 22) (14568400179).jpg

Identifier: belltelephonemag00vol2930amerrich (find matches)
Title: Bell telephone magazine
Year:Spring 1950 (magazine date)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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ut-and-tryexperiments. Many experimentershad had the idea that a solid-stateamplifier should be a practical possi-bility, but all of their attempts tomake one had failed. It was not forlack of trying that such an amplifierwas not invented earlier, but tor lackof understanding. The transistor is as much a prod- uct of invention as was the vacuumtube amplifier; but in the absence ofknowledge of just what goes on atthe contact of a metal point with thesurface of a semi-conductor, no onehad the basis tor conceiving how tomake an amplifier from a germaniumcrystal with a couple of metallicpoints pressing on it. It was to getan understanding, ami with a confi-dence that something useful wouldcome out of it, that a systematic re-search on the properties of semi-con-ductors was organized. Semi-conductors are those mate-rials in the solid state intermediate inconductivity between metals and in-sulators. Silicon and germanium aretwo such materials. We had a spe- 12 Bell Telephone Magazine SPRING
Text Appearing After Image:
Set beside an ordinary paper clip, thisregionalized transistor reveals its diminu-tive size :ial interest in them because of appli-cations we were making of these ma-terials in certain control devices andin rectifiers for very high frequencies. One of the characteristics of ger-manium, and also of silicon, is that itmay exist in either of two states de-pending on the presence of minute im-purities. In one of these states ametallic point in contact with it willpass current in one direction but notthe other, and in the second state thedirection of rectification is reversed.This oddity is explained by those whounderstand solid-state conduction asdue in one case to conduction of elec-tricity by a slight excess of free elec-trons, which conduct electricity in thesame manner as free electrons inmetals, and in the other case to con-duction by the transfer of holes where electrons might be but are notbecause of a deficiency of supply. On purely theoretical grounds,there was reason to believe

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