Nitrogen-doped YAG : Ce3+ phosphors have been firstly studied by using hexamethylenetetramine (HMT) as a nitrogen source by a solid state reaction. The optimal content of HMT is by introducing 50 wt.% with precursors of Y2O3, Al2O3 and CeO2 under annealing at 1450 degrees C for 8 hours. The XRD data indicate that the lattice constants increase with the content of HMT. SEM morphologies demonstrate that after nitrogen doping, the surface and particle size of YAG become smoother and larger than un-treated one. The PL intensity of YAG : Ce after HMT treatment gives a incensement in range of 3.46% similar to 9.87%. The luminous efficacy of as-synthesized YAG : Ce phosphor + Blue chip was dramatically enhanced by 40%. Using the doped samples, the white LED luminous efficiency obtained 78.4 lm/W and was successfully obtained with the combination of blue LED chip, thus improving the performance of the LED. The enhancement in luminesce was resulted from the modification of its surface morphology, crystallinity and grain size.

Keywords: Hexamethylenetetramine; Nitrogen; Light emitting diodes; Phosphors