FORMATION OF GAN MICRO-CRYSTALS BY THE DIRECT REACTION OF NH3 WITH A GA-MELT

GaN micro-crystals were formed by using the direct reaction of NH3 wit h a Ga-melt. The bubbling technique was employed in an atmospheric NH3 ambient for about 20 hours at 850-1100 degrees C to achieve an effect ive reaction of the NH3 gas with the Ga-melt. A dark-gray-colored GaN material was formed. The GaN micro-crystals were synthesized without i ntentional nucleations and were refined by a chemical solution of HNO3 + HF. A kind of microcrystalline hexagonal structure was found from s canning electron microscope, X-ray diffraction, and Photoluminescence measurements. The systhesized GaN micro-crystals with a typical dimens ion of 0.5 - 3 mu m can be used as material for electronic devices or as a source material for growing thick GaN films by specific preparati on techniques such as the sublimation method.