Visible Light-Emitting Diodes - The Formative Years |
| Journal |
Materials Science Forum (Volume 590) |
| Volume |
Advances in Light Emitting Materials |
| Edited by |
Bo Monemar, Martin Kittler, Hermann Grimmeiss |
| Pages |
1-16 |
| DOI |
10.4028/www.scientific.net/MSF.590.1 |
| Online since |
August, 2008 |
| Authors |
J.W. Allen,
Hermann G. Grimmeiss
|
| Keywords |
Gallium Nitride, Gallium Phosphide, History, Junction Electroluminescence, Light Emitting Diode (LED), Mixed-Crystal Semiconductor, Silicon Carbide (SiC) |
| Abstract |
A brief history of visible light-emitting diodes (LED's) is given, from the first
experimental observations of H.J.Round in 1907 to the mid-1970's when red and green emitters
were in extensive production. Early investigations were empirical. This was changed with the
invention of the transistor in 1947 by the demonstration of minority carrier injection at a forwardbiased
junction, followed by recombination. In 1952 the discovery of the semiconducting behaviour
of III-V compounds introduced a new range of materials. Gallium nitride seemed attractive for light
emission and was investigated at Philips and RCA laboratories but at the time proved to be too
difficult for practical use. Gallium phosphide emerged as the most promising material and groups to
investigate it were set up at SERL in England, Philips Central Research Laboratories in Germany
and Bell Telephone Laboratories in the USA. Zinc and oxygen doping gave red emission. At
Philips, the emphasis was on efficiencies. At SERL the emphasis was on reproducibility for
manufacturable devices and when the conditions for zinc and oxygen doping were strictly
controlled the world's first practical visible LED's were produced at the end of 1961. At Bell
Telephone Laboratories progress was initially slow but with the advent of liquid-phase epitaxial
growth production of red emitters on the scale required became possible. The accidental discovery
of nitrogen doping of gallium phosphide at Bell led to the production of good green emitters. Until
the 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. |
| Full Paper |
Get the full paper by clicking here
|
| Preview |
Free first page example |
