Fabrication of Light Emitting Diodes

A diode made of a compound of gallium (Ga), arsenic (AS), and phosphorus (P) can radiate visible light when electrons and holes recombine, so it can be used with It can be used to make light-emitting diodes, used as indicator lights in circuits and instruments, or to form text or digital displays. Gallium arsenide phosphide diodes emit red light, gallium phosphide diodes emit green light, and silicon carbide diodes emit yellow light.  It is a type of semiconductor diode that can convert electrical energy into light energy; often abbreviated as LED.

Light-emitting diodes are composed of a PN junction like ordinary diodes, and also have unidirectional conductivity. When a forward voltage is applied to the light-emitting diode, the holes injected from the P region to the N region and the electrons injected from the N region to the P region will be respectively connected with the electrons in the N region and the empty holes in the P region within a few microns of the PN junction. Hole recombination, resulting in spontaneous emission of fluorescence.

The energy states of electrons and holes in different semiconductor materials are different. When electrons and holes recombine, the energy released is somewhat different, the more energy released, the shorter the wavelength of the light emitted. Commonly used are diodes that emit red, green or yellow light.    

LED classification  

LEDs can also be divided into ordinary monochrome LEDs, high-brightness LEDs, ultra-high brightness LEDs, color-changing LEDs, flashing LEDs, voltage-controlled LEDs, Infrared light emitting diodes and negative resistance light emitting diodes, etc.