Already at the end of the 1950s, the possibility of a new lighting technology using GaN,
the bandgap of which had just been measured, was seriously considered at Philips
Research Laboratories. H.G. Grimmeiss and H. Koelmans obtained efficient
photoluminescence from GaN over a wide spectral range using different activators and
a patent was filed [16]. However, at that time it was very difficult to grow GaN crystals.
Only small crystals, forming a powder, could be produced, in which p-n junctions could
not be created. The researchers at Philips decided to concentrate on GaP instead (see
above).
GaN crystals