Light emitting diode is the semiconductor device that converts electrical energy into optical energy by the phenomenon of injection that is in a semiconductor crystal and electron-hole transitions, semiconductor hetero junction. In the light emitting diode when the flow in it AC or DC in the domain of the semiconductor adjacent to this transition (contacts) are injected excess charge carriers- electrons and holes, and their recombination is accompanied by optical radiation. Light Emitting Diode emits incoherent radiation, but in contrast to the heat light sources, with a narrower spectrum, so that the radiation in the visible region is perceived as one color.
In the light emitting diode infrared radiations are used in devices, optical location, optical communication, a range finder etc. A matrix of light emitting diode is a device input and output of computers. In some areas of light emitting diode computers with its sister unit the injection laser which generates coherent light differs from light emitting diode from the crystal and the mode of operation. (Perry, 1995)
The efficiency of light emitting diode of visible light ranges from 0.01% to several percent. In the light emitting diode infrared radiation to reduce losses at the total internal reflection and absorption in the body of the crystal for the last pick hemispherical shape and to improve the characteristics of the radiation light emitting diode placed in a parabolic or conical reflector. Efficiency of the light emitting diode with hemispherical shape of the crystal is 40 %. (Zheludev, 2007)
Industry produces light emitting diode in a discrete and integral execution. Discrete light emitting diode of visible light is used as a signal indicator, integrated or the multi-element devices, light emitting digital-character display, profile scale, multi-panel and flat screens used in various systems of ...