How does an LED make light?

How does an LED make light?

As we saw on the previous FAQ“Where does light come from?”, electrons at higher orbits that drop back to lower orbits, release photons of light. In LED semiconductors, a similar strategy is at work. Electrons jump from higher energy states to lower energy states.

Electron movement in Semiconductors
LED semiconductors have two layers. The top semiconductor layer, called n-type, is modified to have extra free electrons. The bottom layer, called p-type, is also modified, but to have positively charged “electron holes” (but not really “holes”, more like pockets), which can attract free electrons. When current is passed through these two layers, the electrons and holes move toward each other - when an electron is close enough to a hole, it falls into it, going from a high energy state to a low state (hole) and as we already know, this releases a photon.
1. Negative free electrons in n-type layer and positive holes in p-type layer are in a steady state.
2. Current is applied from top to bottom - the positive holes moves toward the negative pole of current, electrons move toward the positive pole.
3. As an electron (at a higher energy state) passes a hole, it falls into it (lower energy state). The release of energy emits a photon of bluish color.
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UPRtek How does an LED make light? Introduction

United Power Research Technology Corp. is Taiwan supplier and manufacturer in Optoelectronics Industry. UPRtek has been offering our customers high quality Spectrometer, Color Meter, Spectral PAR Meter, Spectral Color Meter, Spectrum, LED Meter, Spectradiometer, LED Measurement, LED light testing since 2010. With both advanced technology and 8 years experience, UPRtek always make sure to meet each customer's demand.


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