Light-emitting diode

A semiconductor device that emits light when electric current flows through it. Its color depends mainly on the semiconductor’s band gap.

Electroluminescence: Light emission caused by an electric field or electric current acting on a material. An LED is a semiconductor example of this broader light-emission process.
Semiconductor: A material whose electrical conductivity lies between that of a conductor and an insulator and can be controlled. LEDs are semiconductor devices whose optical behavior depends on composition and doping.
Solid-state lighting: Lighting produced by semiconductor devices rather than incandescent filaments or gas discharges. LEDs are the dominant technology behind modern solid-state lighting.
H. J. Round: A British engineer who reported light emission from silicon carbide in 1907. His observation is an early documented report of electroluminescence in a solid.
P–n junction: A boundary between p-type and n-type semiconductor regions, where mobile-carrier behavior changes. The junction’s electric field and carrier injection enable light production in many LEDs.
Doping (semiconductor): The intentional addition of impurities to change a semiconductor’s charge-carrier concentration. Doping creates the p-type and n-type regions used to form an LED junction.
White LED: An LED-based light source that produces white light, commonly by converting blue light with a phosphor. Phosphor-converted white LEDs made efficient general-purpose LED lighting practical.
Oleg Losev: A Russian physicist who investigated and published on semiconductor light-emitting devices in the 1920s. His work described practical crystal-based light emitters decades before commercial LEDs.
Electron–hole recombination: The process in which an electron fills a hole in a semiconductor, releasing energy. In an LED, some recombination energy leaves the semiconductor as photons.
Forward bias: A voltage polarity across a semiconductor junction that lowers its barrier and permits substantial current. Forward bias injects carriers across the LED junction so they can recombine.

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