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Thermoelectric properties of superlattice materials with variably spaced layers

Published online by Cambridge University Press:  29 July 2011

T.D. Musho  and
D.G. Walker
T.D. Musho*
Affiliation:
Interdisciplinary Materials Science, Vanderbilt University, Nashville, Tennessee 37212
D.G. Walker*
Affiliation:
Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212
*
a)Address all correspondence to this author. e-mail: greg.walker@vanderbilt.edu
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Abstract

Variably spaced semiconductor superlattices (VSSLs) exhibited superior electron mobility and rectification because of electronic level alignment. We investigated the thermoelectric properties of VSSL structures using a self-consistent nonequilibrium Green’s function quantum model to capture the ballistic electron transport and anatomistic nonequilibrium Green’s function model to capture the phonon transport. A figure of merit was calculated as a function of temperature for two VSSL strain silicon–germanium materials and a non-VSSL material. Calculation of the figure of merit (ZT) versus temperature for a VSSL demonstrated a 17 times increase in power factor at the expense of a 4 times increase in thermal conductivity at room temperature compared to a comparable uniform superlattice. Calculation determined a ZT of 0.20 for a VSSL compared to a ZT of 0.04 for non-VSSL material at 400 K. VSSLs proved to be a candidate material to further increased ZT near room temperature for superlattice materials.

Keywords

simulationthermal conductivitythermoelectric
Type
Articles
Information
Journal of Materials Research , Volume 26 , Issue 15: Focus Issue: Advances in Thermoelectric Materials , 14 August 2011 , pp. 1993 - 2000
Copyright
Copyright © Materials Research Society 2011

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