What is a light emitting diode (LED)?

Explanation

Light emitting diodes (LED) are specially made p-n junction diode (gallium arsenide phosphide-GaAsP) in which when current is made to flow in the forward direction, visible light is emitted from the region of the depletion layer.
When `p-n` junction is forward biased, the potential barrier gets lowered, the conduction band electrons from n-region cross the barrier and enters the p-region . Also some holes may cross the junction from p region to n-region. A conduction band electron in the p-region may fall into a hole, even before it crosses the junction . In either case, recombination takes place around the junction. Each recombination radiates energy in a visible form. Such light emitting diodes are called LED for short.