The modification of nitrogen configuration is a viable way to control the electronic properties of nitrogen-doped carbon nanotube. N-doping could be performed during synthesis or through post-treatment process. Carbon nanotubes were synthesized by chemical vapor deposition (CVD) process using ethanol as carbon source. It was found that upon increasing irradiation level, a slight blue shift in the G-band frequency is observed along with a slight shift toward higher binding energy, owing a possible n-type doping characteristic. Due to the weak N1s signal, the irradiated N2 could effect on the nanotube structure when strong ?-irradiation and high pressure N2 atmosphere are employed.