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Title: Thermoelectric properties of the 3C, 2H, 4H, and 6H polytypes of the wide-band-gap semiconductors SiC, GaN, and ZnO

We have investigated the thermoelectric properties of the 3C, 2H, 4H, and 6H polytypes of the wide-band-gap(n-type) semiconductors SiC, GaN, and ZnO based on first-principles calculations and Boltzmann transport theory. Our results show that the thermoelectric performance increases from 3C to 6H, 4H, and 2H structures with an increase of hexagonality for SiC. However, for GaN and ZnO, their power factors show a very weak dependence on the polytype. Detailed analysis of the thermoelectric properties with respect to temperature and carrier concentration of 4H-SiC, 2H-GaN, and 2H-ZnO shows that the figure of merit of these three compounds increases with temperature, indicating the promising potential applications of these thermoelectric materials at high temperature. The significant difference of the polytype-dependent thermoelectric properties among SiC, GaN, and ZnO might be related to the competition between covalency and ionicity in these semiconductors. Our calculations may provide a new way to enhance the thermoelectric properties of wide-band-gap semiconductors through atomic structure design, especially hexagonality design for SiC.
Authors:
;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [2]
  1. Department of Physics, and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China)
  2. (Malaysia)
  3. (China)
Publication Date:
OSTI Identifier:
22492375
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 9; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BOLTZMANN EQUATION; CONCENTRATION RATIO; COVALENCE; ENERGY GAP; GALLIUM NITRIDES; POWER FACTOR; SEMICONDUCTOR MATERIALS; SILICON CARBIDES; TEMPERATURE DEPENDENCE; THERMOELECTRIC MATERIALS; THERMOELECTRIC PROPERTIES; TRANSPORT THEORY; ZINC OXIDES