ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A brief history of visible light-emitting diodes (LED's) is given, from the firstexperimental observations of H.J.Round in 1907 to the mid-1970's when red and green emitterswere in extensive production. Early investigations were empirical. This was changed with theinvention of the transistor in 1947 by the demonstration of minority carrier injection at a forwardbiasedjunction, followed by recombination. In 1952 the discovery of the semiconducting behaviourof III-V compounds introduced a new range of materials. Gallium nitride seemed attractive for lightemission and was investigated at Philips and RCA laboratories but at the time proved to be toodifficult for practical use. Gallium phosphide emerged as the most promising material and groups toinvestigate it were set up at SERL in England, Philips Central Research Laboratories in Germanyand Bell Telephone Laboratories in the USA. Zinc and oxygen doping gave red emission. AtPhilips, the emphasis was on efficiencies. At SERL the emphasis was on reproducibility formanufacturable devices and when the conditions for zinc and oxygen doping were strictlycontrolled the world's first practical visible LED's were produced at the end of 1961. At BellTelephone Laboratories progress was initially slow but with the advent of liquid-phase epitaxialgrowth production of red emitters on the scale required became possible. The accidental discoveryof nitrogen doping of gallium phosphide at Bell led to the production of good green emitters. Untilthe end of the 1970's, gallium phosphide red and green emitters dominated the LED market.Subsequent developments to the present day are sketched in outline
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/19/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.590.1.pdf
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