Formation of gallium nitride particles during the two-stage chemical vapor process

The effects of the reaction temperature in the first stage TI on the formation and the luminescent property of both the seed and the grown particles were investigated in the region from 1050 to 1200 °C for the two-stage vapor-phase synthesis of GaN particles. The reaction efficiency of vaporized Ga and NH3 to form the seed particles increased with increasing TI up to about 1150 °C, where the maximum value of about 70% was obtained. Further raising TI caused a decrease of the efficiency. The X-ray diffraction and the photoluminescence (PL) measurements indicated both of the crystal quality and the luminescent property of the seed particle were improved with increasing TI. On the other hand, the PL intensity of the particles grown on the seed in the second stage decreased with increasing TI. This difference in the dependence was explained in terms of the morphology of the grown particles. The mechanism of particle formation during these processes was also discussed based on the results.