Thermal Dispersion Metrics and Phonon Wavepacket Scattering at Silicon-Germanium Interfacial Defects

International Journal of Physics | Vol. 5, No. 10, October 2014 | pp. 73–80

DOI: 10.46882/2014/IJP/000054

Research Article

Title: Thermal Dispersion Metrics and Phonon Wavepacket Scattering at Silicon-Germanium Interfacial Defects

Names of Authors: M. G. Richter¹, C. H. Jenkins²

Authors’ Affiliations: ¹Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany; ²Space Sciences Laboratory, University of California, Berkeley, California 94720, USA

Abstract: Minimizing thermal transport across semiconductor boundary layers is crucial for designing high-efficiency solid-state thermoelectric cooling devices. This paper uses molecular dynamics simulations to quantify thermal dispersion metrics and track phonon wavepacket scattering at defective silicon-germanium (Si-Ge) interfaces. We constructed atomistic models using the optimized Stillinger-Weber potential, incorporating varying concentrations of interfacial point defects and atomic roughness steps. 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 5.0 THz) undergo strong diffuse scattering at the rough interface, dropping the transmission coefficient from 0.82 down to 0.24. This diffuse scattering is driven by localized strain fields and localized interface vibrational modes. The overall interfacial thermal conductance was calculated to decrease by 45.0% when the interfacial 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 electronics.

Keywords: Thermal dispersion; phonon wavepacket; molecular dynamics; interface roughness; thermoelectric cooling; silicon-germanium

Manuscript Timeline: Received: June 11, 2014; Revised: August 04, 2014; Accepted: August 28, 2014; Published: October 17, 2014

Citation: Richter, M. G., & Jenkins, C. H. (2014). Thermal Dispersion Metrics and Phonon Wavepacket Scattering at Silicon-Germanium Interfacial Defects. International Journal of Physics, 5(10), 73–80.

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