History of LED development

Update:30 Sep 2019
Summary:

Henry Joseph Round first observed electroluminescence i […]

Henry Joseph Round first observed electroluminescence in a piece of silicon carbide in 1907. Because its yellow light is too dark, no
Suitable for practical application; more difficult is that silicon carbide and electroluminescence can not be well adapted, research has been abandoned.
Bernhard Gudden and Robert Wichard used yellow phosphorus from zinc sulfide and copper in Germany in the late 1920s.
Once again, it stopped because of the dim light. In 1936, George Destiau published a report on the emission of zinc sulfide powder. With current
The term "electroluminescence" came into being with wide application and recognition.
In the 1950s, British scientists invented the first of modern significance by using the semiconductor GaAs in electroluminescent experiments.
LED, and appeared in the 1960s. It is said that in the early test, LED needs to be placed in liquefied nitrogen, and further operation and breakthroughs are needed to achieve high performance.
Efficiency works at room temperature. The first commercial LED can only emit invisible infrared light, but it is rapidly applied in the field of induction and optoelectronics. 60s
Finally, the first visible red LED was invented using phosphide on GaAs substrate. GaP changes make LEDs more efficient and emit more red light.
Bright, even produce orange light.
By the mid-1970s, gallium phosphide was used as a light source, and then grey-white and green light was emitted. LED uses double-layer GaP stamen (one red)
The other color is green) can emit yellow light. At this point, Russian scientists used diamond to produce yellow LED. Although it's not as good as Europe.
Continental LED is efficient. But in the late 1970s, it emitted pure green light.
The use of GaAs and Aluminum Phosphide in the early to mid-1980s led to the birth of the first generation of high-brightness LEDs, first red and then yellow.
Finally, it's green. By the early 1990s, indium-aluminium-gallium phosphide was used to produce orange, orange, yellow and green LED. The first is historic.
Blu-ray LEDs also appeared in the early 1990s, once again using gold sand, an obstacle to early semiconductor light sources. To balance according to today's technical standards
Quantity, it is as dim as the Yellow LED before Russia.
In the mid-1990s, superluminous GaN LEDs appeared, and then high-intensity green and blue indium GaN Leds were produced. Super bright
Degree blue pistil is the core of white LED, which is coated with phosphorus fluorescence, then phosphorus fluorescence is absorbed by the blue light source from the pistil.
Convert to white light. This technology is used to produce any visible color of light. Novelty colors can be seen in the LED market today.
Such as light green and pink. Readers with scientific ideas may now realize that the development of LED has gone through a long and tortuous historical process. matter
In fact, the recently developed LED can emit not only pure ultraviolet light, but also real "black" ultraviolet light. So the development history of LED goes to low energy
How far is it? Maybe someday we can develop an X-ray LED. Early LEDs can only be used for indicator lights and early calculator displays.
And digital watches. And now it's beginning to appear in the field of superluminance. It will continue for some time to come.

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