A light-emitting diode (LED) is based on a forward-biased heterojunction and emits narrow-band radiation whose wavelength is determined by the bandgap of the semiconductor material. Recently-developed white LEDs are typically based on blue LEDs (InGaN,indium gallium nitride) coated with doped YAG (yttrium aluminum garnet) crystals which act as a phosphor,down-converting part of the blue radiation to a broad spectrum centreed in the yellow. The resulting spectral mix has appearance of white light to the human eye. Shown here are two white LEDs in 5-mm packages. (Aug 2007) | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Giphotostock |
Bildgröße: | 2991 px × 4500 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: |
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