Non-reactive rf treatment of multiwall carbon nanotube with inert argon plasma for enhanced field emission

External rf plasma irradiation of well-aligned multiwall carbon nanotubes (MWCTs) was demonstrated as a simple purification process. The plasma exposure to argon (Ar) gas was performed in situ in order to modify any structural defects and to vaporize contamination of the MWCTs grown at the extremely low temperature of 400 °C. Scanning electron microscopy and transmission electron microscopy confirmed the catalytic particle removal from the MWCT edges. In addition, Fourier transformer infrared spectroscopy and energy dispersive spectrometry showed that Ar plasma atoms were not chemically terminated by carbon atoms because of the inertness of the Ar atoms. The structural enhancement in the MWCTs resulted in a reduction of the turn-on field from 1.65 V/μm to 0.93 V/μm and an increase in the field emission current.