'Another early character to have touched LEDs is Kurt Lehovec, who is best known for inventing junction isolation for integrated circuits when he worked for Sprague, patenting it in 1959.
Less well known is that in 1952 he applied for a patent on SiC visible light LEDs.
He appears to have grown n-type SiC doped with arsenic, then locally introducing boron with an electron beam to make p-SiC for the junction.
In the patent he speaks of ‘activator’ impurities including silver, lead, manganese, bismuth, thallium, tin, copper, zinc, cerium, europium and samarium which are proposed to control the colour of light, noting blue, greenish-yellow and pale yellow emission.
Lehovec seems to have made a manganese activated SiC LED, measuring operation to over 200kHz, and proposes it be used to record the audio track down the edge of movie film.'
- link to pdf file google search
