LED structure and the light-emitting principle
The LED light-emitting diode, is a solid state semiconductor devices, which can be converted directly into electricity for light. The heart of the LED is a semiconductor wafer, light emitting diodes
One end of the chip attached to a bracket, one end is negative, the other end to connect the positive power supply, so that the entire chip to be epoxy encapsulated. The semiconductor chip consists of two parts, the part of the P-type semiconductor, the dominant hole in it, the other end of the N-type semiconductor, here is mainly electronic. But when two semiconductor connected to form a PN junction between them. When the current through the wire to the chip, the electrons would be pushed to the P region in the P region electron-hole recombination, and then will be issued in the form of photon energy, which is the principle of led tube. The wavelength of light is the color of light is determined by the material to form a PN junction. The initial LED as the light of the instructions of the instrumentation, then a variety of light-colored LEDs in traffic lights and a large area display a wide range of applications, resulting in a good economic and social benefits. To 12 inches of red traffic lights, for example, in the United States was long-lived, low-efficiency 140-watt incandescent lamp as a light source, it produces 2000 lumens of white light. The red filter, the light loss of 90%, leaving only 200 lumens of red light. In the light of the new design, Lumileds uses 18 red RGB LED light source, including circuit losses, the total power consumption of 14 watts to produce the same luminous efficiency. The car lights are also an important area of ??the LED light source applications.
For general lighting, people need a white light source. 1998 white light LED development. The LED is packaged together to make the GaN chip and yttrium aluminum garnet (YAG). GaN chip of blue (λp = 465nm yellow light shot Wd = 30nm), high-temperature sintering of YAG phosphors with Ce3 + by blue excitation peak 550nm. Blue Spot Light substrate is installed in the reflective cavity bowl, covered with a mixture of YAG thin layer of resin, about 200-500nm. led light issued by the blue part was absorbed by the phosphor, another part of the Blu-ray phosphors emit yellow mixed, can be too white. InGaN / YAG white[ LED tube>http://www.top-led-china.com/] by changing the YAG phosphor chemical composition and to adjust the thickness of the phosphor layer can be colored white color temperature 3500-10000K. This blue LED is white, simple structure, low cost, mature technology and high, so the use of up to
60s of last century, scientists use light-emitting principle of semiconductor PN junction, development became a LED light diodes. The development of the LED diode, the materials used GaASP its luminous color is red. After nearly 30 years of development, and now very familiar with the LED, can emit red, orange, yellow, green, blue shade. However, the white light LED lighting required only developed in recent years to introduce readers to the lighting, white LED.