Universal features of phonon transport in nanowires with correlated surface roughness

Abstract

The ultralow thermal conductivity $\kappa$ observed experimentally in intentionally roughened silicon nanowires (SiNWs) is reproduced in phonon Monte Carlo simulations with exponentially correlated real-space rough surfaces similar to measurement [J. Lim, K. Hippalgaonkar, S. C. Andrews, A. Majumdar, and P. Yang, Nano Lett. 12, 2475 (2012)]. Universal features of thermal transport are revealed by presenting $\kappa$ as a function of the normalized geometric mean free path $\bar{\lambda }$ ($0<\bar{\lambda }<1$); the diffusive (Casimir) limit corresponds to $\bar{\lambda }=1/2$. $\kappa$ vs $\bar{\lambda }$ is exponential at low-to-moderate roughness (high $\bar{\lambda }$), where internal scattering randomly interrupts phonon bouncing across the SiNW, and linear at high roughness (low $\bar{\lambda }$), where multiple scattering events at the same surface results in ultralow, amorphous-limit thermal conductivity.

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Cited by in corpus (4)

• Non-diffusive Lattice Thermal Transport in Si-Ge Alloy Nanowires
• Enhanced Phonon Boundary Scattering at High Temperatures in Hierarchically Disordered Nanostructures
• Computationally efficient Monte Carlo electron transport algorithm for nanostructured thermoelectric material configurations
• Effect of wave versus particle phonon nature in thermal transport through nanostructures