Sunday, 19 August 2012

A Lecture on Semiconductor Physics by a Nobel Lauriate

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In 1947 Shockley, Bardeen, and Brattain invented the first bipolar point-contact transistor. They were jointly awarded the 1956 Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect." In the following half hour video, Brattain explains semiconductors and ends with a demo of an LED. Excellent.

However, light emission from semiconductors was noticed long before this -

Electroluminescent Silicon Carbide Crystals in 1907
An Early Light Emitting Diode.

A Note on Carborundum, from Electrical World Feb 9th 1907

To the Editors of Electrical World:

SIRS:- During an investigation of the unsymmetrical passage of current through a contact of carborundum and other substances a curious phenomenon was noted. On applying a potential of 10 volts between two points on a crystal of carborundum, the crystal gave out a yellowish light. Only one or two specimens could be found which gave a bright glow on such a low voltage, but with 110 volts a large number could be found to glow. In some crystals only edges gave the light and others gave instead of a yellow light green, orange or blue. In all cases tested the glow appears to come from the negative pole, a bright blue-green spark appearing at the positive pole. In a single crystal, if contact is made near the center with the negative pole, and the positive pole is put in contact at any other place, only one section of the crystal will glow and that the same section wherever the positive pole is placed.

There seems to be some connection between the above effect and the e.m.f. produced by a junction of carborundum and another conductor when heated by a direct or alternating current; but the connection may be only secondary as an obvious explanation of the e.m.f. effect is the thermoelectric one. The writer would be glad of references to any published account of an investigation of this or any allied phenomena.

New York. H.J.Round.

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Unrelated to this post, below is an example of
eclectic science esoterica 

Brave pilot has just launched a live Genie air to air nuclear rocket. Below, the result -
1.5-kiloton W25 nuclear warhead,
Plumbbob John Test, 15000 ft

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