A light-emitting diode (LED) is a semiconductor device that emits light when an electric current is passed through it. They combine a P-type semiconductor (larger hole concentration) with an N-type semiconductor (larger electron concentration). Light is produced when the particles that carry the current (known as electrons and holes) combine together within the semiconductor material.
LEDs are devices that create light when an electrical current is applied. This lighting technology is known as solid-state lighting (SSL). Unlike most other light sources, which use a filament or gas to produce light, LEDs are based on the flow of electrons through a solid semiconductor material. SSL also includes OLEDs (organic LEDs), which like LEDs create light from a flow of electrons through a semiconductor material.
Aluminum gallium indium phosphide (AlGaInP): yellow, orange, and red high-brightness LEDs
Aluminum gallium arsenide (AlGaAs): red and infrared LEDs
Indium gallium nitride (InGaN): blue, green, and ultraviolet high-brightness LEDs
Gallium phosphide (GaP): yellow and green LEDs
What Are The Different Colors?
Inside every semiconductor material, there are energy bands for positively charged electrons and negatively charged “holes”, as well as a bandgap where such holes exist. The separation of these bands determines the energy of the photons that are emitted by the LED.
Photon energy determines the wavelength of the emitted light, and hence its color. Different semiconductor materials with different bandgaps produce different colors of light. The precise wavelength (color) can be tuned by altering the composition of the light-emitting, or active, region.
Light-emitting diodes (LEDs) are the fastest-growing technology for controlling light. LEDs are solid-state devices made up of mixed crystal materials from groups III and V of the periodic table. These crystals are formed into semiconductor structures that emit light and energy when forward biased by an external source.
Previously, although LEDs had been developed from red to a combination of colors (white), the range was limited by technology and practicality. However, the development of GaN technology allowed for the creation of blue-based white LEDs and made possible the color range available today.