LED (Light Emitting Diode) is a solid-state semiconductor device, which can directly convert electricity into light. The core of LED is semiconductor chip. One end of the chip is attached to the bracket, one end is the negative electrode, and the other end is connected to the positive electrode of the power supply, so that the whole chip is encapsulated by epoxy resin. The semiconductor wafer consists of two parts, one is a P-type semiconductor, in which holes are dominant, and the other is an N-type semiconductor, mainly electrons. But when these two semiconductors are connected together, a "pn junction" is formed between them. When the current acts on the chip through the wire, the electrons will be pushed to the P region, where they will recombine with holes and then release energy in the form of photons, which is the principle of LED light emission. The wavelength of light determines the color of light, and the color of light is determined by the material that constitutes the pn junction.

The structure of the blue chip is mainly: substrate-buffer layer-undoped gallium nitride -N-type confinement layer -MQW-P-type confinement layer -P-type conductive layer -PN electrode.