First Principles Investigation of Electronic and Electrical Properties of Carbon Nanotube Interfaces

In the last two decades, researchers have been studying various interaction issues between electrodes (primarily metals) and single-wall carbon nanotubes (SWCNTs), including contact resistance. To create electronic devices and electrical circuits based on SWCNTs, it is crucial to have a better understanding of how the interface between the electrode and the nanotube influences contact resistance. The electronic and electrical characteristics of SWCNT (6,6) in contact with other SWCNTs were investigated using density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods using the SIESTA software package. We explored the rotation of SWCNTs relative to electrodes and obtained dependences of resistance, band structures, and local density of states (LDOS) for SWCNT models as a function of rotation angle. In cases where the electrodes and central tube were identical, a three-fold decrease in conductance was observed at 12 degrees. The resistance behavior was due to the localization of electrons near the interface, as confirmed by the LDOS analysis. When the electrodes and central tube were different, the calculated resistances were very high, making these interface configurations ineffective for circuit applications.