Thermal Dispersion Metrics and Phonon Scattering at Silicon-Germanium Core-Shell Nanowire Boundaries

International Journal of Physics | Vol. 9, No. 8, August 2018 | pp. 57–64

DOI: 10.46882/2018/IJP/000100

Research Article

Title: Thermal Dispersion Metrics and Phonon Scattering at Silicon-Germanium Core-Shell Nanowire Boundaries

Names of Authors: M. G. Richter¹, D. W. Meyer²

Authors’ Affiliations: ¹Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany; ²Institute of Physics, Karlsruher Institut für Technologie, Karlsruhe, Germany

Abstract: Minimizing thermal transport across semiconductor boundary layers is crucial for designing high-efficiency solid-state thermoelectric cooling devices and protecting microcircuit nodes. This paper uses molecular dynamics simulations to quantify thermal dispersion metrics and track phonon wavepacket scattering at defective silicon-germanium (Si-Ge) core-shell nanowire interfaces. We constructed atomistic models using the optimized Stillinger-Weber potential, incorporating varying concentrations of interfacial point defects and shell thickness distributions. Longitudinal and transverse acoustic phonon wavepackets were generated with narrow frequency spreads centered between 2.0 THz and 8.0 THz. The computational data demonstrate that high-frequency acoustic phonons (f greater than 5.2 THz) undergo strong diffuse scattering at the rough shell interface, dropping the transmission coefficient from 0.84 down to 0.20. This diffuse scattering is driven by localized strain fields and localized interface vibrational modes. The overall interfacial thermal conductance was calculated to decrease by 50.0% when the interface roughness parameter scaled from 0.1 nm to 0.6 nm at 300.0 K. These molecular dynamics calculations clarify the atomic-scale mechanisms restricting heat carrier propagation, helping engineers design targeted thermal barriers for nanoscale optoelectronic devices.

Keywords: Thermal dispersion; phonon wavepacket; molecular dynamics; core-shell nanowires; thermoelectric cooling; silicon-germanium

Manuscript Timeline: Received: April 05, 2018; Revised: June 01, 2018; Accepted: June 28, 2018; Published: August 14, 2018

Citation: Richter, M. G., & Meyer, D. W. (2018). Thermal Dispersion Metrics and Phonon Scattering at Silicon-Germanium Core-Shell Nanowire Boundaries. International Journal of Physics, 9(8), 57–64.

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