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Impacts of cone-structured interface and aperiodicity on nanoscale thermal transport in Si/Ge superlattices |
Pengfei JI1, Yiming RONG1, Yuwen ZHANG2(), Yong TANG3 |
1. Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China 2. Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211, USA 3. Key Laboratory of Surface Functional Structure Manufacturing of Guangdong Higher Education Institutes, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China |
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Abstract Si/Ge superlattices are promising thermoelectric materials to convert thermal energy into electric power. The nanoscale thermal transport in Si/Ge superlattices is investigated via molecular dynamics (MD) simulation in this short communication. The impact of Si and Ge interface on the cross-plane thermal conductivity reduction in the Si/Ge superlattices is studied by designing cone-structured interface and aperiodicity between the Si and Ge layers. The temperature difference between the left and right sides of the Si/Ge superlattices is set up for nonequilibrium MD simulation. The spatial distribution of temperature is recorded to examine whether the steady-state has been reached. As a crucial factor to quantify thermal transport, the temporal evolution of heat flux flowing through Si/Ge superlattices is calculated. Compared with the even interface, the cone-structured interface contributes remarkable resistance to the thermal transport, whereas the aperiodic arrangement of Si and Ge layers with unequal thicknesses has a marginal influence on the reduction of effective thermal conductivity. The interface with divergent cone-structure shows the most excellent performance of all the simulated cases, which brings a 33% reduction of the average thermal conductivity to the other Si/Ge superlattices with even, convergent cone-structured interfaces and aperiodic arrangements. The design of divergent cone-structured interface sheds promising light on enhancing the thermoelectric efficiency of Si/Ge based materials.
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Keywords
thermoelectric material
thermal transport
Si/Gesuperlattics
molecular dynamics (MD)
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Corresponding Author(s):
Yuwen ZHANG
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Online First Date: 09 January 2018
Issue Date: 08 March 2018
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