A light-emitting semiconductor device
A light-emitting diode (LED) is a semiconductor device that emits light when a forward voltage is applied to it. The fact that certain semiconductors emit light has been observed by a number of semiconductor researchers from early on. After it was successfully demonstrated in 1960 that ruby could be used as a source of laser, inspired researchers sought to produce laser beams using the electroluminescence effect of semiconductors.
At the time, compound semiconductors based on gallium arsenide (GaAs) and other materials were attracting greater attention than silicon-based semiconductors. Since GaAs is superior to silicon in terms of electric properties at high frequencies, it was considered to be suitable for laser applications, too. After a fierce competition among researchers, three American teams separately conducted successful experiments on LEDs in 1962.