A semiconductor device that converts electrical energy into light or infrared radiation in the range from 550 nm (green light) to 1300 nm (infrared radiation). The most commonly used LED emits red light and consists of gallium arsenide–phosphide on a gallium arsenide substrate, light being emitted at a p–n junction when electrons and holes recombine (see recombination process). LEDs are extensively used for displaying letters and numbers in digital instruments in which a self-luminous display is required. In the early 1990s Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura invented blue LEDs that allow the production of energy-efficient white light; for this work they were awarded the Nobel Prize for physics in 2014.
Light-emitting diode.
See LED display.
A p-n junction diode that emits light as a result of direct radiative recombination of excess electron-hole pairs (see recombination processes). In direct-gap semiconductors, such as gallium arsenide, it is a major part of recombination and a significant amount of light will be emitted following injection of excess minority carriers. The quantity of light produced in a forward-biased p-n junction diode formed from such material will be proportional to the numbers of excess minority carriers, i.e. to the bias current. The useful light obtained from the diode is dependent on the optical quality of the crystal surfaces. The frequency, and hence the colour, is a property of the material used, since the energy of the emitted photon is determined by the band-gap energy. LEDs are useful for low-voltage display devices, such as calculators or digital watches, and are now widely used in flatscreen displays. Single LEDs are widely used as on/off indicators. See also active-matrix organic light-emitting diode; organic light-emitting diode.
https://www.youtube.com/watch?v=Yo6JI_bzUzo A video tutorial on LED basics
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