Abstract
The question of what bandstructure produces the best thermoelectric device performance is revisited from a Landauer perspective. We find that a delta-function transport distribution function (TDF) results in operation at the Mahan-Sofo upper limit for the thermoelectric figure-of-merit, ZT. We show, however, the Mahan-Sofo upper limit itself depends on the bandwidth (BW) of the dispersion, and therefore, a finite BW dispersion produces a higher ZT when the lattice thermal conductivity is finite. Including a realistic model for scattering profoundly changes the results. Instead of a narrow band, we find that a broad BW is best. The prospects of increasing ZT through high valley degeneracy or by distorting the density-of-states are discussed from a Landauer perspective. We conclude that while there is no simple answer to the question of what bandstructure produces the best thermoelectric performance, the important considerations can be expressed in terms of three parameters derived from the bandstructure - the density-of-states, D(E), the number of channels, M(E), and the mean-free-path, k(E)
Date of this Version
2012
Published in:
On the best bandstructure for thermoelectric performance: A Landauer perspective. Changwook Jeong, Raseong Kim, and Mark S. Lundstrom. J. Appl. Phys. 111, 113707 (2012)
Comments
Copyright (2012) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 111, 113707 (2012) and may be found at http://dx.doi.org/10.1063/1.4727855. The following article has been submitted to/accepted by Journal of Applied Physics. Copyright (2012) Changwook Jeong, Raseong Kim, and Mark S. Lundstrom. This article is distributed under a Creative Commons Attribution 3.0 Unported License