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Quantum Confinement Effects on the Thermoelectric Figure of Merit in Si/Si1−xGex System

Published online by Cambridge University Press:  15 February 2011

X. Sun ,
M. S. Dresselhaus ,
K. L. Wang  and
M. O. Tanner
X. Sun
Affiliation:
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
M. S. Dresselhaus
Affiliation:
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
K. L. Wang
Affiliation:
Department of Electrical Engineering, University of California, Los Angeles, CA 90024
M. O. Tanner
Affiliation:
Department of Electrical Engineering, University of California, Los Angeles, CA 90024
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Abstract

The Si/Sil−xGex quantum well system is attractive for high temperature thermoelectric applications and for demonstration of proof-of-principle for enhanced thermoelectric figure of merit Z, since the interfaces and carrier densities can be well controlled in this system. We report here theoretical calculations for Z in this system, and results from theoretical modeling of quantum confinement effects in the presence of δ-doping within the barrier layers. The δ-doping layers are introduced by growing very thin layers of wide band gap materials within the barrier layers in order to increase the effective barrier height within the barriers and thereby reduce the barrier width necessary for the quantum confinement of carriers within the quantum well. The overall figure of merit is thereby enhanced due to the reduced barrier width and hence reduced thermal conductivity, K. The δ-doping should further reduce K in the barriers by introducing phonon scattering centers within the barrier region. The temperature dependence of Z for Si quantum wells is also discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 478: Symposium Q – Thermoelectric Materials - New Directions and Approaches , 1997 , 169
Copyright
Copyright © Materials Research Society 1997

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