Description: The first bipolar junction transistors were invented by Bell labs William Shockley, which applied for patent(2,569,347) on June 26, 1948. On April 12, 1950, Bell Labs chemists Gordon Teal and Morgan Sparks had successfully produced a working bipolar NPN junction amplifying germanium transistor. Bell Labs had made this new sandwich transistor discovery announcement, in a press release on July 4, 1951.[18][19]
Philco surface-barrier transistor developed and produced in 1953
The first high-frequency transistor was the surface-barrier germanium transistor developed by Philco in 1953, capable of operating up to 60 MHz.[20] These were made by etching depressions into an N-type germanium base both sides with jets of Indium(III) sulfate until it was a few ten-thousandths of an inch thick. Indium electroplated into the depressions formed the collector and emitter.[21][22]
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