- Aug 24, 2016 -
LED light source, LED by Ⅲ - Ⅳ compounds, such as GaAs (gallium arsenide), GaP (gallium phosphide), GaAsP phosphorus (GaAs) made of semiconductor, such as its core is the p-n junction. So it is usually the I - V characteristics of p-n junction, which is the wizard, reverse blocking, the breakdown characteristic. In addition, under certain conditions, it also has a luminescence properties. Under the forward voltage, the electronic by N area into P area, hole by P area into N area. Part into the area of minority carrier (Jane) with majority carrier (children) composite and shine.
Assume that light is in the P region, then injected electrons and the valence band hole composite and shine directly, or be luminous center after capture, hole composite luminescence again. In addition, this kind of light composite some electrons are not luminous center (the center between the conduction band, interface with near middle) capture, then with hole compound, every time the energy released is not big, could not form visible light. Amount of composite luminescence relative to the amount of light composite, the greater the proportion of light quantum efficiency is higher. Because the compound is glowing in the Jane diffusion zone, so the light only near the surface of p-n junction generated within a few microns.
Theory and practice has proved that the peak wavelength of light lambda is associated with light emitting area of semiconductor materials band gap Eg, namely the lambda material 1240 / Eg (mm)
Type of Eg unit for electron volts (eV). If you can produce visible light wavelength (780 nm to 380 nm violet light red light), Eg of semiconductor materials should be between 3.26 ~ 1.63 eV. Long wavelength than red light for infrared light. Existing infrared, red, yellow, green and blue leds, but the blue light diode costs, the price is high, the use is not widespread.
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