Science · 6 pages · 12 min
How an LED makes light without a hot filament
Electrons and holes recombine in a semiconductor, and the energy leaves as a photon.
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From the opening
An LED makes light when electrons and holes meet in a semiconductor and the electron drops to a lower energy, releasing a photon. The chip does not have to be a hot filament, because that photon comes from the electronic jump rather than from a material glowing with temperature. The opening covers why recombination emits a photon, how the energy gap sets color, and what a phosphor adds for white.
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Inside
- Why recombination emits a photon
- How the energy gap sets color
- What a phosphor adds for white
- Why the chip can still warm up
- Where the idea stops applying
- A distinction worth keeping
Sources
- Electroluminescence at a semiconductor p-n junction
- Band-gap energy that sets the color of the photon