LED Videowall

Henry Joseph Round first observed in 1907 that inorganic substances under the influence of an applied voltage to a light emission compliant. 1921 discovered the Russian physicist Oleg Vladimirovich Losev Round the effect again, and looked at him from 1927 to 1942 precisely because he suspected that the phenomenon as a reversal of Einstein, photoelectric effect is to interpret. George Destriau discovered in 1935 a similar zinc sulphide luminous phenomenon and named it after the Russian physicist Lossew than light.

In the follow-up period was from 1951 by the development of the transistor, a scientific advance in the semiconductor physics can be achieved. Next, it was possible, the process of light emission enlighten. Initially, however, continue to experiment with zinc sulphide. Success, however, the research on semiconductor recognized as the III-V compound. In 1957 focused on the study of light generation on the whole semiconductor. Especially the emission of light in the visible range based on gallium arsenide (GaAs) and gallium (GaP) was important.

Other sources attribute the invention of the LED, however Nick Holonyak and dated it to the 1962nd

In the course of development, since the first LEDs in 1962, was the light output by about three orders of magnitude from <0.1 lumens / watt at> 100 lumens / watt increase. These predominantly in large jumps occurred except developmental steps based on the better quality of semiconductor layers (lower defect densities, fewer impurities) on the use of semiconductor heterostructures, low dimensional structures (quantum pots), transparent substrates and the improved light outcoupling. Based on GaAs / Alas (1960, red-yellow), new semiconductor materials such as GaP (1970s, green LEDs) and GaN (1980er/1990er years, green to UV) was developed so that today almost all the LEDs in the colors of the spectrum (up to a gap in the green-yellow area) are. Especially after semiconductors, the light in the shortwave range (blue, UV) effectively produce, has been long sought. Main problem was a long time, the doping of a P-frame by appropriate senior breitlückigen semiconductors for the first time in 1988 the group of GaN Akasaki succeeded in Japan, then in 1992 to Shuji Nakamura with another approach. The latter led to the first commercial blue LED on GaN-based, which is now extended to include white and green LEDs and blue lasers, since 1993, distributed by Nichia. Until then blue LEDs based on silicon carbide material which is an indirect semiconductor for efficient light emission is poorly suited.

Increasing the efficiency and lower cost of semiconductor manufacturing is the goal of further developments. Currently, most efforts, both transparent substrates and semiconductor materials as well as transparent electrical connection lines. The bond wires (electrical lines to the semiconductor chip) to cover a portion of the active surface.
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