Abstract
We Use Equilibrium Molecular Dynamics Simulations to Determine the Relative Role of Compositional and Structural Disorder in a Phononic Thermal Conductivity Reduction by Studying Three 50-50 SiGe Alloy Structures: Ordered Alloys, Disordered Alloys, and Amorphous Alloys, as Well as Pure Amorphous Si and Ge Structures for Reference. While Both Types of Disorders Significantly Reduce Thermal Conductivity, Structural Disorder is Much More Effective to This Aim. the Examination of Phonon Lifetimes in Disordered Alloys Shows High Values in a Low Frequency Regime Governed by Umklapp Scattering that Are Reduced Rapidly with Increasing Frequency Following Rayleigh Scattering Behavior. the Local Properties Analysis Reveals that the Structural Disorder Leads to Elastic Heterogeneities that Are Significantly Larger Than Density Heterogeneities, Which is Likely the Key Reason for Amorphous Semiconductor Alloys Having Lower Thermal Conductivity Than Disordered Alloys. Temperature Dependence of Thermal Conductivity Indicates the Importance of Propagating Phonons and Associated Umklapp Scattering in SiGe Alloy Structures. Interestingly, Longitudinal Modes in Amorphous and Disordered Alloys Exhibit Similar Lifetimes, While Transverse Modes Lifetimes Show Significant Differences and Are More Temperature Dependent.
Recommended Citation
J. Nie et al., "Structural vs.. Compositional Disorder in Thermal Conductivity Reduction of SiGe Alloys," Journal of Applied Physics, vol. 122, no. 4, article no. 45104, American Institute of Physics, Jul 2017.
The definitive version is available at https://doi.org/10.1063/1.4994169
Department(s)
Mechanical and Aerospace Engineering
International Standard Serial Number (ISSN)
1089-7550; 0021-8979
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2023 American Institute of Physics, All rights reserved.
Publication Date
28 Jul 2017
