Blue light-emitting diodes (LEDs) are really bright. Too bright for theorists to handle, in fact. Why? Because, the materials from which they are made usually have impurities that should make their glow much duller. Now, an international team of researchers has discovered why this is the case.
Commercially viable blue LEDs are based on the wide band gap semiconductor gallium nitride and indium gallium nitride and were invented by Shuji Nakamura then at the Nichia Corporation in 1993. By the late 1990s, they were widely available and now sit in an important technological niche in the development of large full-colour displays, LEDs for highly energy-efficient solid-state lighting to replace incandescent bulbs, and 400 nanometre laser diodes for optical data storage in high definition DVDs. However, the commonly used indium gallium nitride can only be manufactured at relatively low quality with high levels of impurities. Theoretically at least these impurities should quench the light the device produces, but it does not.
Full story out now, under the Intute Spotlight