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Title: 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 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<10{sup 18} cm{sup −3}). A largemore » value of ZT{sub ||} (parallel to the growth direction) of 3.0 is predicted for n=4.7×10{sup 18} cm{sup −3} and T=700 K, whereas ZT{sub p} (perpendicular to the growth direction) is found to peak at 1.5 for n=1.7×10{sup 17} cm{sup −3}. Both electrical conductivity enhancement and thermal conductivity reduction are analyzed. - Graphical abstract: Figure of merit for PbTe/SnTe/PbTe heterostructure along the [0 0 1] direction, P.D. Borges, J.E. Petersen, L. Scolfaro, H.W. Leite Alves, T.H. Myers, Improved thermoelectric properties of IV–VI-based heterostructures and superlattices. - Highlights: • Thermoelectric properties of IV–VI-based heterostructures and superlattices. • High figure of merit is predicted for the PbTe/SnTe/PbTe heterostructure. • Nanotechnology has an important role for the development of thermoelectric devices.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [3]
  1. Instituto de Ciências Exatas e Tec., Universidade Federal de Viçosa, Rio Paranaíba, MG (Brazil)
  2. (United States)
  3. Department of Physics, Texas State University, San Marcos, TX 78666 (United States)
  4. Departamento de Ciências Naturais, Universidade Federal de São João Del Rei, Caixa Postal 110, São João Del Rei 36300-000, MG (Brazil)
Publication Date:
OSTI Identifier:
22475690
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 227; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BISMUTH; BOLTZMANN EQUATION; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; DENSITY FUNCTIONAL METHOD; DOPED MATERIALS; ELECTRIC CONDUCTIVITY; ELECTRONIC STRUCTURE; FERMI LEVEL; HETEROJUNCTIONS; LEAD TELLURIDES; NANOTECHNOLOGY; SEMICLASSICAL APPROXIMATION; SUPERLATTICES; THALLIUM; THERMAL CONDUCTIVITY; THERMOELECTRIC MATERIALS; THERMOELECTRIC PROPERTIES; TIN TELLURIDES