Current-Induced Restructuring and Chemical Modification of N-Doped Multi-walled Carbon Nanotubes



Multi-walled carbon nanotubes (MWCNTs) have long been anticipated as candidates for electrical components in an increasingly miniaturized electronics industry due to their inherent electrical properties. It is possible to manipulate and control these properties by introducing dopants such as N, B, and P. Although some current-induced structural changes in MWCNTs have been observed, no systematic study has been carried out to explore the correlation of changes in the internal structure with the electronic behavior of doped-MWCNTs in terms of the current densities present. In situ transmission electron microscopy (TEM) investigations are presented here of individual, N-doped MWNCT (N-MWCNTs) using the in situ TEM/scanning tunneling microscopy (TEM/STM) Nanofactory© holder. It is observed for the first time that N-MWCNTs not only undergo current-induced structural transformation; i.e., from the typical bamboo structure of N-MWCNTs to the stacked cones, but also—and most importantly—the complete removal of the dopant causes a significant change in the electronic behavior. This has serious implications for the use of doped CNTs as electronic components, especially since tremendous efforts are being made to synthesize CNTs with controlled dopant concentrations.