Electron-dependent thermoelectric properties in Si/Si 1- xGe x heterostructures and Si 1- xGe x alloys from first-principles

M. Z. Hossain, H. T. Johnson

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Abstract

Unlike phononic thermal conductivity (which is shown in the literature to be reduced due to alloying and has a nearly constant value over a range of compositional variations), electron-dependent thermoelectric properties are shown here, from first-principles, to vary nonlinearly with composition. Of the Si/Si 1-xGe x systems considered, the maximum thermopower observed, which is 10 higher than that of crystalline Si, is obtained for a Si 0.875Ge 0.125 alloy. Also, heterostructuring is shown to reduce thermopower, electrical conductivity, and electron thermal conductivity. Additionally, neither Lorenz number nor Seebeck coefficient shows oscillations for heterostructures, regardless of electron/hole energies, contradicting the conclusions obtained with miniband approximations.

Original languageEnglish (US)
Article number253901
JournalApplied Physics Letters
Volume100
Issue number25
DOIs
StatePublished - Jun 18 2012

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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