GaN and related compounds are nowadays the key materials for so called 'blue optoeletronics'. Thanks to their large, direct gap, they are able to emit the light in the very broad spectral range. The use of nitrides semiconductors made possible the realization of first 'blue light' emitting laser diodes. The biggest obstacle in the development of these devices is the lack of GaN substrate crystals for epitaxy. So far commercial techniques base on sapphire substrates. Sapphire is one of very few materials stable enough to withstand the GaN growth conditions. However incompatibility of crystalline structures of GaN and sapphire leads to the very serious degradation of GaN overlayers quality. In spite of the sophistication of the growth method, the density of dislocations is much to high, specially for the construction of broad-stripe, high-power lasers.
In this presentation I will focus on the application of high quality, high-pressure grown bulk GaN crystals for MBE and MOVPE epitaxy of laser structures, showing the advantages of this technology in particular for manufacturing of high-power laser diodes and UV light emitting devices. I would like to stress that in case of homoepitaxy both MBE and MOVPE methods can give excellent and very comparable results.