-
The
light-emitting section of an LED is made by joining n-type and p-type
semiconductors
together
to form a pn junction.
=
When the pn
junction is forward-biased, electrons in the n side are excited across the pn
junction
and into the p side, where they combine with holes.
§
As the electrons
combine with the holes, photons are emitted.
§
The pn-junction
section of an LED is encased in an epoxy shell that is doped with light
scattering
particles to diffuse light and make the LED appear brighter.
§ Often a reflector placed beneath the semiconductor is
used to direct the light upward.
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its cool