Abstract
Hydrogen plasma irradiation technique was applied to improve UV luminescence properties of commercial GaN powder which contained the dissolved oxygen in GaN lattice and a small amount of Ga2O3. RF induction thermal plasma of pulse-modulated mode was used to generate a high concentration of hydrogen radical species. The treatment of a green compact of GaN powder in the tail flame of Ar-H2 PM-ICP gave rise to the increase of photo luminescent intensity at 380 nm. The strongest intensity was obtained when a GaN specimen was set in the plasma tail flame region, where the numerical analysis predicted the increase of hydrogen radical concentration and the decrease of heat flux. When the treatment time increased, partial decomposition of GaN took place in due to excess heat energy. A short time Ar-H2 plasma irradiation gave the appropriate heating and the optimal emission efficiency. Raman scattering spectroscopy showed the impurity Ga2O3 in plasma-irradiated specimens.
