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About LED

  In the early 20th century, Henry Round of Marconi Labs first noted that a semiconductor junction would produce light. Russian Oleg Vladimirovich Losev independently created the first LED in the mid 1920s; his research, though distributed in Russian, German and British scientific journals, was ignored. Rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide (GaAs) and other semiconductor alloys in 1955. Experimenters at Texas Instruments, Bob Biard and Gary Pittman, found in 1961 that gallium arsenide gave off infrared radiation when electric current was applied. Biard and Pittman were able to establish the priority of their work and received the patent for the infrared light-emitting diode. Nick Holonyak Jr., then of the General Electric Company and later with the University of Illinois at Urbana-Champaign, developed the first practical visible-spectrum LED in 1962 and is seen as the "father of the light-emitting diode". Holonyak's former graduate student, M. George Craford, invented in 1972 the first yellow LED and 10x brighter red and red-orange LEDs.  

  Shuji Nakamura of Nichia Corporation of Japan demonstrated the first high-brightness blue LED based on InGaN, borrowing on critical developments in GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN which were developed by I. Akasaki and H. Amano in Nagoya . In the 1995 Alberto Barbieri at the Cardiff University Laboratory (GB) investigated the Efficiency and Reliability of high-brightness LED demonstrating very high result by using a transparent contact made by indium tin oxide (ITO) on (AlGaInP/GaAs) LED. The existence of the blue LED and high efficiency quickly carried to the first white LED, which employed a Y3Al5O12:Ce, or "YAG", phosphor coating to mix yellow (down-converted) light with blue to produce light that appears white. Nakamura was awarded the 2006 Millennium Technology Prize for his invention.