Journal
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
Volume 29, Issue 12, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0268-1242/29/12/124004
Keywords
grain boundary scattering; Monte Carlo simulations; nanocrystalline thermoelectrics
Categories
Funding
- Robert Bosch LLC through Bosch Energy Research Network [13.01.CC11]
- National Science Foundation [CBET CAREER 1254213]
- Boeing under the Boeing-Caltech Strategic Research & Development Relationship Agreement
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1254213] Funding Source: National Science Foundation
Ask authors/readers for more resources
Nanocrystalline silicon and silicon-germanium alloys are promising thermoelectric (TE) materials that have achieved substantially improved figure of merits compared to their bulk counterparts. This enhancement is typically attributed to a reduction in lattice thermal conductivity by phonon scattering at grain boundaries. However, further improvements are difficult to achieve because grain boundary scattering is poorly understood, with recent experimental observations suggesting that the phonon transmissivity may depend on phonon frequency rather than being constant as in the commonly used gray model. Here, we examine the impact of frequency-dependent grain boundary scattering in nanocrystalline silicon and silicon-germanium alloys in a realistic 3D geometry using frequency-dependent variance-reduced Monte Carlo simulations. We find that the grain boundary may not be as effective as predicted by the gray model in scattering certain phonons, with a substantial amount of heat being carried by low frequency phonons with mean free paths longer than the grain size. Our result will help guide the design of more efficient TEs.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available