Thermal Conductivity Anomalies and Phonon Scattering Mechanisms in Silicon-Germanium Superlattices

International Journal of Physics | Vol. 4, No. 11, November 2013 | pp. 81–88

DOI: 10.46882/2013/IJP/000043

Research Article

Title: Thermal Conductivity Anomalies and Phonon Scattering Mechanisms in Silicon-Germanium Superlattices

Names of Authors: D. W. Meyer¹, Z. L. Wang²

Authors’ Affiliations: ¹Institute of Physics, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany; ²State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, CAS, Beijing 100083, China

Abstract: Controlling thermal transport across semiconductor heterostructures is essential for designing efficient thermoelectric energy harvesters and preventing hotspot formation in nanoelectronics. This study examines cross-plane thermal conductivity anomalies and maps phonon scattering mechanisms in silicon-germanium (Si/Ge) superlattices. We performed molecular dynamics simulations based on the Stillinger-Weber potential, evaluating superlattice periods ranging from 2.0 nm to 20.0 nm at temperatures between 100.0 K and 500.0 K. The calculated data show a non-monotonic dependence of thermal conductivity on the superlattice period. The cross-plane thermal conductivity drops to a minimum value of 4.2 W/m-K at a period of 4.5 nm under room temperature conditions. This minimum point represents a shift from coherent wave-like phonon transport to incoherent particle-like phonon scattering. For periods smaller than 4.5 nm, wave-like transport dominates, and the thermal conductivity scales upward due to the formation of acoustic minibands. For periods larger than 4.5 nm, diffuse interface scattering and Umklapp processes restrict heat carrier lifetimes, yielding an average phonon mean free path of 24.5 nm. These results clarify the wave-particle duality of heat-carrying phonons, assisting in the development of targeted thermal barriers for microprocessors.

Keywords: Superlattices; thermal conductivity; molecular dynamics; phonon scattering; thermoelectricity; wave-particle duality

Manuscript Timeline: Received: July 12, 2013; Revised: September 04, 2013; Accepted: September 22, 2013; Published: November 12, 2013

Citation: Meyer, D. W., & Wang, Z. L. (2013). Thermal Conductivity Anomalies and Phonon Scattering Mechanisms in Silicon-Germanium Superlattices. International Journal of Physics, 4(11), 81–88.

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