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Experimental Study of Phonon-Folding in Si/Ge and Si/Sige Structures Designed for Thermoelectric Applications

Published online by Cambridge University Press:  10 February 2011

J. Liu
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California - Los Angeles, Los Angeles, CA 90095 USA, [email protected]
A. Balandin
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California - Los Angeles, Los Angeles, CA 90095 USA, [email protected]
T. Borca-Tascjuc
Affiliation:
Nanoscale Heat Transfer and Termoelectricity Laboratory, Department of Mechanical and Aerospace Engineering, University of California - Los Angeles, Los Angeles, CA 90095 USA
Y. S. Tang
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California - Los Angeles, Los Angeles, CA 90095 USA, [email protected]
K. L. Wang
Affiliation:
Device Research Laboratory, Electrical Engineering Department, University of California - Los Angeles, Los Angeles, CA 90095 USA, [email protected]
G. Chen
Affiliation:
Nanoscale Heat Transfer and Termoelectricity Laboratory, Department of Mechanical and Aerospace Engineering, University of California - Los Angeles, Los Angeles, CA 90095 USA
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Abstract

We report data of Raman study of Si/Ge and Si/SiGe superlattices designed for thermoelectric applications. The obtained Raman spectra clearly indicate the presence of folded doublets from longitudinal acoustic phonons. Due to the significant difference in the sound velocities for Si and Ge the position of the doublets strongly depends on the superlattice layer thickness and ordering. Comparison of the Raman data for different samples with measured thermal and thermoelectric properties allows us to determine a correlation between the strength of the phonon confinement in these structures and their thermoelectric properties. Our experimental results are consistent with recent theoretical prediction of increased thermoelectric figure of merit in semiconductor quantum wells.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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