Multi-walled carbon nanotubes were irradiated with ultra-low energy (few eV) nitrogen and hydrogen ions using a microwave discharge. These ultra-low energy plasma-ions remained confined to the nanotube walls, transferring their maximum energy to the carbon atoms, and produced extraordinary structural changes in the carbon nanotube pillars as well as within the carbon nanotubes. Conical emitters and nanotube structures with nano-defects were produced that exhibited remarkable field emission with ultra-low turn-on electric field (∼0.16V/μm) and a >300-fold increase in the maximum emission current density, compared to non-irradiated nanotubes. Doping of nitrogen was also identified due to such irradiation processes.

Improved Field Emission From Multiwall Carbon Nanotubes with Nano-Size Defects Produced by Ultra-Low Energy Ion Bombardment. K.S.Hazra, N.A.Koratkar, D.S.Misra: Carbon, 2011, 49[14], 4760-6