International Journal of Physics | Vol. 3, No. 1, January 2012 | pp. 1–9
DOI: 10.46882/2012/IJP/000025
Article Type: Original Research Paper
Title: Phonon Dispersion Relation and Thermal Conductivity Anomalies in Graphene Nanoribbons with Specular Boundary Edge Roughness
Names of Authors: O. T. Sanusi¹, Y. M. Takahashi²
Authors’ Affiliations: ¹Department of Physics, Federal University of Technology, Minna, Nigeria; ²Institute of Industrial Science, University of Tokyo, Tokyo, Japan
Abstract: Managing thermal transport at the nanoscale is essential for avoiding thermal throttling in next-generation ballistic transistors and high-density microprocessor units. This paper models phonon dispersion relations and lattice thermal conductivity variations in armchair and zigzag graphene nanoribbons (GNRs) featuring structural edge roughness. The lattice vibrations were calculated via a modified valence force-field model, while the thermal conductivity profiles were extracted using the phonon Boltzmann transport equation under the relaxation time approximation. The nanoribbon widths were systematically adjusted between 5 nm and 30 nm at operational temperatures up to 500 K. Our simulations reveal that boundary edge roughness induces severe confinement, which reduces lattice thermal conductivity by up to 72% compared to pristine graphene sheets. This dramatic drop stems from enhanced diffuse backscattering of high-frequency acoustic phonons at the rough boundaries. Zigzag configurations displayed a 15% higher thermal tolerance than armchair variants due to localized edge phonon modes that resist phase space scattering. The calculations show that at 300 K, a 10 nm wide nanoribbon exhibits an effective thermal conductivity of 420 W/(m*K). These results provide layout metrics for managing heat dissipation in graphene nano-circuitry.
Keywords: Graphene nanoribbons; Phonon dispersion; Thermal conductivity; Boltzmann transport equation; Edge roughness; Valence force field; Nanoscale heat transfer; Ballistic transistors.
Manuscript Timeline: Received: October 20, 2011; Revised: November 29, 2011; Accepted: December 19, 2011; Published: January 04, 2012.
Citation: Sanusi, O. T., & Takahashi, Y. M. (2012). Phonon Dispersion Relation and Thermal Conductivity Anomalies in Graphene Nanoribbons with Specular Boundary Edge Roughness. International Journal of Physics, 3(1), 1–9.
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