Etching of multi-walled carbon nanotubes using energetic plasma ions

The interactions between energetic ions and nanotubes are important in the fabrication of plasma-aided carbon nanotubes, especially in the process of sputter-etching and particle encapsulation into the nanotubes. In this study, it was investigated that the bamboo structured multi-walled carbon nanotubes (MWNTs) was sputter-etched by plasma ion irradiation with various energies which were less than those used in the ion beam experiments. In the plasma, the surface opening of the MWNTs began at the irradiated ion energy of 20eV and the open tips of the MWNTs were obtained by increasing the irradiated ion energy as 70eV. When the ion energy exceeded 100eV, the etching was enhanced by the rupturing and breaking processes and almost half of the MWNTs were etched out by the 150eV ions. The irradiated ion energy was controlled effectively by the sheath potential formed in front of the MWNTs which was immersed in the nitrogen plasma.