Valence-band structure of highly efficient p-type thermoelectric PbTe-PbS alloys

Christopher M. Jaworski*, Michele D. Nielsen, Hsin Wang, Steven N. Girard, Wei Cai, Wally D. Porter, Mercouri G. Kanatzidis, Joseph P. Heremans

*Corresponding author for this work

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Experimental evidence is given relevant to the temperature dependence of the valence band structure of PbTe and PbTe1-xSxaloys (0.04≤x≤0.12), and its effect on the thermoelectric figure of merit ZT. The x=0.08 sample has ZT∼1.55 at 773 K. The magnetic field dependence of the high-temperature Hall resistivity of heavily p-type (>1019 cm-3) Na-doped PbTe1-xSx reveals the presence of high-mobility electrons. This casts doubts on prior analyses of the Hall coefficient suggesting that temperature induces a rapid rise in energy of the "heavy" hole relative to the "light" hole bands. The electron-like behavior is likely induced by the topology of the Fermi surface when the L- and Σ-bands merge. Negative values for the low-temperature thermopower are also observed. The data show that PbTe continues to be a direct-gap semiconductor at temperatures where the ZT and S2σ of p-type PbTe are optimal, e.g., 700-800 K.

Original languageEnglish (US)
Article number045203
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number4
DOIs
StatePublished - Jan 4 2013

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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