he light emitting diode referred as LED. It is compound of gallium (Ga), arsenic (AS) and phosphorus (P), when the electron and hole recombination can radiate visible light, and thus can be used to form the light emitting diode. LED usually is used as an indicator in the circuit and equipment, or composition for text or digital display. GaAsP diode emit red, gallium phosphide diode produce green, and silicon carbide diodes issue yellow.

Light-emitting diode is a light-emitting semiconductor electronic component. This electronic component developed as early as 1962. At the very beginning, it can only be issued low-luminosity red, later develop other monochromatic version, and today the light emitted throughout the visible, infrared and ultraviolet light, light intensity also increased to a considerable luminosity. As technology continues to progress, the usage of LED are improved from the early indicator and display panel to televisions, lighting, decoration and illumination.