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What’s the point?: The Point Contact transistor

In his 1948 white paper1 , Shockley wrote, “The theory of the point-contact transistor is that the emitter point-contact introduces holes into the n-type base material. The collector point-contact, which is biased negative, withdraws these holes. Current in the emitter point-contact thus controls the current in the collector contact.”

Hole and electron currents in a point-contact transistor. (Image courtesy of reference 1)

Hole and electron currents in a point-contact transistor. (Image courtesy of reference 1)

The general functioning of the point-contact transistor was described by Bardeen and Brattain2 in 1949. The nature of the mechanism of the forming process is one of the central problems of the point-contact transistor.

From the point of view of imperfections in nearly perfect crystals, the situation at point contacts is seen to be in a highly unsatisfactory state so far as fundamental knowledge is concerned. From the point of view of manufacturing control, on the other hand, the situation is quite different, and point-contact transistors can be formed to highly precise tolerances3 .

Schockley’s final conclusion in his article is that transistor electronics is a large and diverse field. It may be expected to show rapid growth for many years to come.

Here is Arlie Stonestreet, chief engineer from Ultra-ICE, holding a point-contact transistor at the 2017 Analog Aficionados dinner. (Image courtesy of Ron Quan)

Here is Arlie Stonestreet, chief engineer from Ultra-ICE, holding a point-contact transistor at the 2017 Analog Aficionados dinner. (Image courtesy of Ron Quan)

Reference

1 PROCEEDINGS OF THE I.R.E., Transistor Electronics: Imperfections, Unipolar and Analog Transistors, W. SHOCKLEY

2 J. Bardeen and W. H. Brattain, “Physical principles involved in transistor action,” Phys. Rev., vol. 75, p. 1208; 1949.

3 J. A. Morton, “Present status of transistor development”, Bell Sys. Tech. Jour., vol. 31, pp. 441-442; 1952.

2 comments on “What’s the point?: The Point Contact transistor

  1. Servilav
    March 13, 2017

    Amazing! i like the discovery

  2. clashroyale
    March 16, 2017

    I can't agree more.

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