Quantum transport and interaction effects in carbon nanotubes and graphene nanoribbons

Abstract

Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) are pivotal in Nano electronics due to their unique quantum transport properties, influenced by electron-electron (e-e) and electron-phonon (e-ph) interactions. This study investigates these effects in a (10,0) zigzag CNT and a 10-armchair GNR using tight-binding models and non-equilibrium Green’s function (NEGF) simulations. We quantify how e-e interactions, driven by Coulomb effects, and e-ph scattering, arising from lattice vibrations, impact conductance and transmission. Results reveal that CNTs exhibit higher conductance (~1.5 G₀, where G₀= 2e²/h) due to weaker e-e scattering (~1011s−1) facilitated by their 1D symmetry and screening. In contrast, GNRs show reduced conductance (~1.0 G₀) due to stronger e-e interactions (~5 × 1011s−1) from edge states and e-ph scattering (1012-1013s−1) enhanced by edge-localized phonons. At 300 K, e-ph coupling dominates, reducing transmission by 30% in CNTs and45%inGNRs, as shown in Fig. 1. Lowering temperature to 77 K mitigates e-ph effects, boosting conductance significantly, though GNRs remain limited by edge contributions. These findings highlight CNTs’ suitability for high-conductance quantum devices and suggest edge engineering (e.g., passivation) to improve GNR performance. By elucidating interaction effects, this work provides a framework for optimizing carbon nanostructures in quantum electronics, addressing scalability and efficiency challenges in next-generation technologies.