Thermoelectric properties of IV–VI-based heterostructures and superlattices

Doping in a manner that introduces anisotropy in order to reduce thermal conductivity is a significant focus in thermoelectric research today. By solving the semiclassical Boltzmann transport equations in the constant scattering time (τ) approximation, in conjunction with ab initio electronic struct...

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Bibliographic Details
Published in:Journal of solid state chemistry 2015-07, Vol.227, p.123-131
Main Authors: Borges, P.D., Petersen, J.E., Scolfaro, L., Leite Alves, H.W., Myers, T.H.
Format: Article
Language:English
Subjects:
BISMUTH
BOLTZMANN EQUATION
COMPARATIVE EVALUATIONS
CONCENTRATION RATIO
DENSITY FUNCTIONAL METHOD
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
FERMI LEVEL
HETEROJUNCTIONS
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
LEAD TELLURIDES
NANOTECHNOLOGY
SEMICLASSICAL APPROXIMATION
SUPERLATTICES
THALLIUM
THERMAL CONDUCTIVITY
THERMOELECTRIC MATERIALS
THERMOELECTRIC PROPERTIES
TIN TELLURIDES
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Summary:Doping in a manner that introduces anisotropy in order to reduce thermal conductivity is a significant focus in thermoelectric research today. By solving the semiclassical Boltzmann transport equations in the constant scattering time (τ) approximation, in conjunction with ab initio electronic structure calculations, within Density Functional Theory, we compare the Seebeck coefficient (S) and figure of merit (ZT) of bulk PbTe to PbTe/SnTe/PbTe heterostructures and PbTe doping superlattices (SLs) with periodically doped planes. Bismuth and Thallium were used as the n- and p-type impurities, respectively. The effects of carrier concentration are considered via chemical potential variation in a rigid band approximation. The impurity bands near the Fermi level in the electronic structure of PbTe SLs are of Tl s- and Bi p-character, and this feature is independent of the doping concentration or the distance between impurity planes. We observe the impurity bands to have a metallic nature in the directions perpendicular to the doping planes, yet no improvement on the values of ZT is found when compared to bulk PbTe. For the PbTe/SnTe/PbTe heterostructures, the calculated S presents good agreement with recent experimental data, and an anisotropic behavior is observed for low carrier concentrations (n
ISSN:0022-4596
1095-726X
DOI:10.1016/j.jssc.2015.03.027