In 1907, Henry Joseph Round for the first time observed electroluminescent phenomenon in a piece of silicon carbide. As its yellow light is too dark, it is not suitable for the actual application. Besides, the silicon carbide could not suit to electroluminescent. Therefore, the study was abandoned. In the late 1920s, Bernhard Gudden and Robert Wichard used yellow phosphorus derived from zinc and copper sulfide in Germany, but once again it was stopped because of the light dim.
In the 1950s, British scientists used semiconductor gallium arsenide in the experiment of electroluminescent, inventing the first LED with modern significance, and it is available in the 1960s. It is said that in the early days of the test, the LED needs to be placed in liquid nitrogen, requiring further operations and breakthrough in order to work more efficiently at room temperature. The first commercial LED was only invisible infrared light, but quickly applied to induction and photoelectric fields. In the late 1960s, phosphide was used on the gaas substrate, inventing the first visible red light LED. The change of the gallium phosphide made LED more efficient and the red light is more bright, even producing orange light.
By the mid 1970s, gallium phosphide was used as light source, and then a gray green came into being. LED adopted double gallium phosphide chip to produce yellow light. Just then, Russian scientists using silicon carbide manufactured yellow LED which may not have high efficiency as European’ s, but it could emit a pure green light in the late 1970s. From the early to the middle of 1980s, gallium arsenide phosphide aluminum is used to give birth to the first generation of high brightness LED, and the first is red, then yellow, and the last green. To the early 1990s, aluminum indium gallium phosphide was adopted to produce orange, yellow and green LED. The first historic blue LED also appeared, using corundum again.
With the development of science and technology, LED is becoming more and more various and functional. It is not difficult to see that the creation of LED is not easy and simple and it is the product gathering many people’ s wisdom and efforts. It deserves to be noticed and praised. It is hoped that you can treasure it.