Light Emitting Diodes

The field of photonics starts with the generation of light. The efficient generation of highly controllable light can indeed be accomplished with light-emitting diodes (LEDs), which are, in principle, capable of generating any single-colored light as well as white light; the latter with a 20 times greater efficiency than conventional lightbulbs. Today, the infrared, entire visible, and ultraviolet spectrum regions can be covered by light-emitting semiconductors, mainly AlGaInP and AlGaInN compound semiconductors. In this entry, fundamental research in LEDs will be presented and reviewed to give a short summary of the development of solid-state LEDs during the last few decades.