論文

査読有り
2020年6月3日

High Thermoelectric Power Factor Realization in Si-Rich SiGe/Si Superlattices by Super-Controlled Interfaces

ACS Applied Materials and Interfaces
  • Tatsuhiko Taniguchi
  • ,
  • Takafumi Ishibe
  • ,
  • Nobuyasu Naruse
  • ,
  • Yutaka Mera
  • ,
  • Md Mahfuz Alam
  • ,
  • Kentarou Sawano
  • ,
  • Yoshiaki Nakamura

12
22
開始ページ
25428
終了ページ
25434
記述言語
掲載種別
研究論文(学術雑誌)
DOI
10.1021/acsami.0c04982

A Si-based superlattice is one of the promising thermoelectric films for realizing a stand-alone single-chip power supply. Unlike a p-type superlattice (SL) achieving a higher power factor due to strain-induced high hole mobility, in the n-type SL, the strain can degrade the power factor due to lifting conduction band degeneracy. Here, we propose epitaxial Si-rich SiGe/Si SLs with ultrathin Ge segregation interface layers. The ultrathin interface layers are designed to be sufficiently strained, not to give strain to the above Si layers. Therein, a drastic thermal conductivity reduction occurs by larger phonon scattering at the interfaces with the large atomic size difference between Si layers and Ge segregation layers, while unstrained Si layers preserve a high conduction band degeneracy leading to a high Seebeck coefficient. As a result, the n-type Si0.7Ge0.3/Si SL with controlled interfaces achieves a higher power factor of ∼25 μW cm-1 K-2 in the in-plane direction at room temperature, which is superior to ever reported SiGe-based films: SiGe-based SLs and SiGe films. The Si0.7Ge0.3/Si SL with controlled interfaces also exhibits a low thermal conductivity of ∼2.5 W m-1 K-1 in the cross-plane direction, which is ∼5 times lower than the reported value in a conventional Si0.7Ge0.3/Si SL. These results demonstrate that strain and atomic differences controlled by ultrathin layers can bring a breakthrough for realizing high-performance light-element-based thermoelectric films.

リンク情報
DOI
https://doi.org/10.1021/acsami.0c04982
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/32427454
Scopus
https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85086052102&origin=inward
Scopus Citedby
https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85086052102&origin=inward
ID情報
  • DOI : 10.1021/acsami.0c04982
  • ISSN : 1944-8244
  • eISSN : 1944-8252
  • PubMed ID : 32427454
  • SCOPUS ID : 85086052102

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