Tony Smith at The Register:
The Light Emitting Diode (LED) is 50 years old. Well, kind of…
It’s certainly 50 years since Nick Holonyak, working at GEC’s Syracuse, New York facility, developed what is considered the first LED capable of generating visible light. Holonyak’s LED was also the first to be in form ready for commercial usage. He wrote up his work and sent it off to Applied Physics Letters on 17 October 1962. The journal published the work in December 1962 under the headline ‘Coherent (visible) Light Emission from GaAs xPx Junctions’.
However, Holonyak’s work followed that of Gary Pittman and Robert Baird who, in 1961, observed the emission of infrared light by Gallium Arsenide — the GaAs in Holonyak’s headline — and, on the back of it, applied for and gained a patent — US number 3,025,589 — for the infrared LED.
[. . .]
Follow the literature back and you end up in Britain in February 1907, with the work of Marconi assistant Henry Round, who first observed the emission of light from a crystal of silicon carbide when a current was applied to it, a phenomenon called electroluminescence. In that sense, the LED is more than 100 years old. Round, however, never wrote a report on his findings.
