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Saturday, January 21, 2012

How does a Light Emitting diode (LED) work?


Light Emitting Diode (LED) is always operated in forward bias mode.


Direct band semiconductors are used for LEDs.

Before applying voltage




After applying voltage



At sufficient voltage, electrons gain sufficient voltage so that they combine with holes to give light which has color that depends on energy gap of chosen semiconductor.

The wavelength of emitted light depends on energy gap and is expressed as 1.24 / Eg; where Eg is energy gap.