Quenched phonon drag in silicon nanowires reveals significant effect in the bulk at room temperature

Jyothi Sadhu, Hongxiang Tian, Jun Ma, Bruno Azeredo, Junhwan Kim, Karthik Balasundaram, Chen Zhang, Xiuling Li, P. M. Ferreira, S. Sinha

Research output: Contribution to journalArticle

Abstract

Existing theory and data cannot quantify the contribution of phonon drag to the Seebeck coefficient (S) in semiconductors at room temperature. We show that this is possible through comparative measurements between nanowires and the bulk. Phonon boundary scattering completely quenches phonon drag in silicon nanowires enabling quantification of its contribution to S in bulk silicon in the range 25-500 K. The contribution is surprisingly large (∼34%) at 300 K even at doping of ∼3 × 1019 cm-3. Our results contradict the notion that phonon drag is negligible in degenerate semiconductors at temperatures relevant for thermoelectric energy conversion. A revised theory of electron-phonon momentum exchange that accounts for a phonon mean free path spectrum agrees well with the data.

Original languageEnglish (US)
Pages (from-to)3159-3165
Number of pages7
JournalNano letters
Volume15
Issue number5
DOIs
StatePublished - May 13 2015

Keywords

  • Seebeck effect
  • electron-phonon scattering
  • phonon drag
  • silicon nanowires
  • thermoelectrics

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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