Role of inter-tube coupling and quantum interference on electrical transport in carbon nanotube junctions

• Electronic properties of carbon nanotube homo-junctions have been studied.
• An Extended Hückel theory/Non Equilibrium Green’s Function based model was applied.
• Conductance oscillations for changes in alignment between the tubes were found.
• Oscillations are ascribed to coupling, carrier scattering and quantum interference.

Due to excellent transport properties, Carbon nanotubes (CNTs) show a lot of promise in sensor and interconnect technology. However, recent studies indicate that the conductance in CNT/CNT junctions are strongly affected by the morphology and orientation between the tubes. For proper utilization of such junctions in the development of CNT based technology, it is essential to study the electronic properties of such junctions. This work presents a theoretical study of the electrical transport properties of metallic Carbon nanotube homo-junctions. The study focuses on discerning the role of inter-tube interactions, quantum interference and scattering on the transport properties on junctions between identical tubes. The electronic structure and transport calculations are conducted with an Extended Hückel Theory-Non Equilibrium Green's Function based model. The calculations indicate conductance to be varying with a changing crossing angle, with maximum conductance corresponding to lattice registry, i.e. parallel configuration between the two tubes. Further calculations for such parallel configurations indicate onset of short and long range oscillations in conductance with respect to changing overlap length. These oscillations are attributed to inter-tube coupling effects owing to changing π orbital overlap, carrier scattering and quantum interference of the incident, transmitted and reflected waves at the inter-tube junction.

This work presents a theoretical study of the electrical transport properties of metallic carbon nanotube junctions. Here the results indicate conductance to be varying with a change in morphology and overlap between the two tubes with maximum conductance for parallel configurations. Further calculations for such parallel configurations indicate onset of short and long range oscillations in conductance with respect to changing overlap length. These oscillations are attributed to inter-tube coupling effects owing to changing ππ orbital overlap, carrier scattering and quantum interference of the incident, transmitted and reflected waves at the inter-tube junction.Figure optionsDownload as PowerPoint slide