GaN films were deposited on sapphire(0 0 0 1) and Si (1 0 0) subsrmtes by MOCVD using an atomic nitrogen source based on a dielectric barrier discharge (DBD) method. Molecule nitrogen and trimethylgallium (TMG) were separately delivered to the substrates. Wurtzite GaN films, with no trace of cubic GaN. were successfully grown on alpha-Al2O3 substrates even at relatively low temperatures ( < 800 degrees C). Sapphire subrtrate RMS roughness was 5.01 and 1.93 Angstrom before and after the exposure to DBD N-source. respectively. This shows negligible irradiation damage of accelerated N-2(+) ion as well as the effect of smoothening the substrate surfaces with DBD N-source. The PL results exhibited small luminescence at the spectral region of blue and UV but a luminescence around the yellow region (2.5 eV) was detected. This is caused by oxygen impurity from AES analysis.