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How do LED lights glow?

2022-04-02


(1) What is LED?


LED, or "Light Emitting Diodes", is a semiconductor called "Light Emitting Diode". It is the real unsung hero of the electronic world. Compared with traditional light sources that convert electrical energy into heat energy and then into light energy, LEDs convert electrical energy into electrical energy. Converts directly into light energy, enabling efficient light emission with minimal waste of electricity.

(2) How does the LED light emit light?


LEDs consist of two semiconductor materials (p-type and n-type). p-type and n-type materials are achieved by doping the background material with atoms of another element. These new atoms replace some of the pre-existing atoms, thereby changing the physical and chemical structure.


P-type materials are created using elements such as boron that have fewer valence electrons than the intrinsic material (usually silicon). N-type materials are made using elements such as phosphorus that have more valence electrons than the intrinsic material (usually silicon). The net effect is that a pn junction is created. When a forward voltage is applied to the pn junction, the free electrons from the n-side and the holes from the p-side recombine to emit invisible light or visible light. Each electron-hole recombination emits some light energy.

(3) Types of LEDs


There are two types of LEDs, one is lamp type (with leads) and one is chip type (surface mount).

(4) What determines the color of the LED?


The material used to construct an LED determines its color. In terms of energy band theory, the wavelength or color of the emitted light depends on the forbidden band or energy gap of the material, and different materials emit different colors of light. Gallium Arsenide LEDs emit red and infrared light; Gallium Nitride LEDs emit bright blue light; Yttrium Aluminum Garnet LEDs emit white light; Gallium Phosphide LEDs emit red, yellow, and green light; Aluminum Gallium Nitride LEDs emit ultraviolet light ; Aluminum Gallium Phosphide LEDs emit green light.