The Effect of Interface Angle on the Thermal Conductivity of Si/Ge Superlattices

Abstract

Si/Ge superlattices (SLs) are good candidates for thermoelectric materials because of their remarkable thermal insulating performance compared with their bulk counterparts. In this paper, the non-equilibrium molecular dynamics (NEMD) simulation method was applied to investigate the thermal conductivity of Si/Ge SLs containing tilted interfaces. It was found that the thermal conductivity will be 4-5 times higher than that of other angles when the period length is 4-8 atomic layers and the interface angle is 45°. This phenomenon can be attributed to the smooth arrangement of the 45° interface which induces phonon coherent transport. Meanwhile, the thermal conductivity has not been improved due to the phonon localization although the phonons satisfy the coherent transport when the interface angle is 90°. Interestingly, the thermal conductivity is almost unchanged with the increasing interface angle when the period length is large enough which exceeds 20 atomic layers. The main reason for the unchanged thermal conductivity is due to the period length which is greater than the phonon coherence length inducing the phonon incoherent transport.

Department(s)

Physics

Comments

The authors are grateful for the funding from the National Natural Science Foundation of China (52076080), the Natural Science Foundation of Hebei Province (E2020502011), and the Fundamental Research Funds for the Central Universities (2020MS105).

International Standard Serial Number (ISSN)

1463-9076

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2021 Royal Society of Chemistry, All rights reserved.

Publication Date

28 Oct 2021

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